WorldWideScience

Sample records for combustion gas sensing

  1. Combustion synthesis of tin dioxide nanocomposites for gas sensing applications

    Science.gov (United States)

    Bakrania, Smitesh Dhirajlal

    The current work focuses on understanding the mechanisms controlling tin dioxide (SnO2) nanoparticle morphology in combustion synthesis systems and how nanoarchitecture affects performance of solid-state gas sensors. A range of analytical methods (including transmission and scanning electron microscopy, x-ray diffraction, nitrogen absorption, and XEDS) were used to characterize the materials properties as a function of the combustion synthesis conditions. A novel method of generating tin dioxide materials was developed which provides a new degree of control over SnO2 morphology; including spherical, nanorod and encapsulated particle architectures. A simplified model for particle formation based on characteristic times was developed to identify the physical and chemical processes affecting the morphologies observed using transmission electron microscope imaging. The SnO2 nanoparticles evolve from primary particles sizes of 7 nm to 14 nm through the synthesis region, and the results indicate interparticle collision and sintering are the dominant mechanisms in determining particle size and morphology for the flame conditions studied. Metal acetates were used to create metal/SnO 2 nanocomposite materials, and the processes controlling gold acetate decomposition in particular were explored. The results of the studies suggest a relationship between the precursor crystallite size and the product nanoparticles. The well-characterized SnO2 particles were evaluated as the active materials for gas-sensing. Sensor sensitivity and time response to carbon monoxide in dry air was used to investigate microstructure-performance links. Excellent sensitivity (3 7, based on the ratio of the resistance of the sensor in air to the resistance in the target gas) and time response (4--20 seconds) were demonstrated for the thin film gas sensors. Fabrication studies demonstrated the sensor performance was a strong function of the film deposition method. A novel method for manufacturing

  2. Silicon Carbide Micro-devices for Combustion Gas Sensing under Harsh Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ruby Ghosh; Reza Loloee; Roger Tobin

    2008-09-30

    A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device, Pt/SiO{sub 2}/SiC that can detect hydrogen-containing species in chemically reactive, high temperature (600 C) environments. We demonstrate that the device can be used as a hydrogen monitor in syngas applications of common interferants as well as sulfur and water vapor. These measurements were made in the Catalyst Screening Unit at NETL, Morgantown under atmospheric conditions. The sensor response to hydrogen gas at 350 C is 240 mV/decade, this is significantly higher than the device response to room temperature gas or that predicted from vacuum chamber studies. The enhanced catalytic activity of the platinum sensing film under energy plant operating conditions was investigated via AFM, x-ray diffraction, TEM and x-ray photoelectron spectroscopy. Our characterization indicated that exposure to high temperature gases significantly modifies the morphology of the Pt catalytic film and the Pt/SiO{sub 2} interfacial region, which we tentatively attribute to the enhanced hydrogen sensitivity of the sensing film. A model for the hydrogen/oxygen response of the SiC device under atmospheric conditions was developed. It is based on two independent phenomena: a chemically induced shift in the metal-semiconductor work function difference and the passivation/creation of charged states at the SiO{sub 2}-SiC interface. The optimum operating set point for the SiC sensor with respect to response time and long term reliability was determined to be close to mid-gap. Ultrahigh vacuum (UHV) techniques were used to investigate the effects of sulfur contamination on the Pt gate. Exposure to hydrogen sulfide, even in the presence of hydrogen or oxygen at partial pressures of 20-600 times greater than the H2S level, rapidly coated the gate with a monolayer of sulfur. Although

  3. SILICON CARBIDE MICRO-DEVICES FOR COMBUSTION GAS SENSING UNDER HARSH CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Ruby N. Ghosh; Peter Tobias; Roger G. Tobin

    2004-10-01

    A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen containing species in chemically reactive, high temperature environments. For these capacitive sensors we have determined that the optimum sensor operating point in terms of sensor lifetime and response time is at midgap. Detailed measurements of the oxide leakage current as a function of temperature were performed to investigate the high temperature reliability of the devices. In addition, robust metallization and electrical contacting techniques have been developed for device operation at elevated temperatures. To characterize the time response of the sensor responses in the millisecond range, a conceptually new apparatus has been built. Using laser induced fluorescence imaging techniques we have shown that the gas underneath the sensor can be completely exchanged with a time constant under 1 millisecond. Ultrahigh vacuum studies of the surface chemistry of the platinum gate have shown that sensor deactivation by adsorbed sulfur is a possible problem. Investigations on the chemical removal of sulfur by catalytic oxidation or reduction are continuing.

  4. Silicon Carbide Micro-devices for Combustion Gas Sensing under Harsh Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ruby N. Ghosh; Reza Loloee; Roger G. Tobin; Yung Ho Kahng

    2006-04-01

    A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen-containing species in chemically reactive, high temperature environments. For fast and stable sensor response measurements, a gate activation process is required. Activation of all sensors took place by switching back and forth between oxidizing (1.0% oxygen in nitrogen) and reducing (10% hydrogen in nitrogen) gases for several hours at a sensor temperature {ge}620 C. All 52 devices on the sensor chip were activated simultaneously by flooding the entire chip with gas. The effects of activation on surface morphology and structure of Pt gates before and after activation were investigated. The optical images obtained from Pt gates demonstrated a clear transition from a smooth and shiny surface to a grainy and cloudy surface morphology. XRD scans collected from Pt gates suggest the presence of an amorphous layer and species other than Pt (111) after activation. The reliability of the gate insulator of our metal-oxide-SiC sensors for long-term device operation at 630 C was studied. We find that the dielectric is stable against breakdown due to electron injection from the substrate with gate leakage current densities as low at 5nA/cm{sup 2} at 630 C. We also designed and constructed a new nano-reactor capable of high gas flow rates at elevated pressure. Our reactor, which is a miniature version of an industrial reactor, is designed to heat the flowing gas up to 700 C. Measurements in ultrahigh vacuum demonstrated that hydrogen sulfide readily deposits sulfur on the gate surface, even at the very high hydrogen/hydrogen sulfide ratios (10{sup 3}-10{sup 5}) expected in applications. Once deposited, the sulfur adversely affects sensor response, and could not be removed by exposure to hydrogen at the temperatures and pressures accessible in

  5. SILICON CARBIDE MICRO-DEVICES FOR COMBUSTION GAS SENSING UNDER HARSH CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Ruby N. Ghosh; Peter Tobias; Roger G. Tobin

    2004-04-01

    A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen containing species in chemically reactive, high temperature environments. Robust metallization and electrical contacting techniques have been developed for device operation at elevated temperatures. To characterize the time response of the sensor responses in the millisecond range, a conceptually new apparatus has been built. Software has been developed to cope with the requirements of fast sensor control and data recording. In addition user friendly software has been developed to facilitate use of the SiC sensors for industrial process control applications.

  6. Structural, magnetic and gas sensing properties of nanosized copper ferrite powder synthesized by sol gel combustion technique

    Science.gov (United States)

    Sumangala, T. P.; Mahender, C.; Barnabe, A.; Venkataramani, N.; Prasad, Shiva

    2016-11-01

    Stoichiometric nano sized copper ferrite particles were synthesized by sol gel combustion technique. They were then calcined at various temperatures ranging from 300-800 °C and were either furnace cooled or quenched in liquid nitrogen. A high magnetisation value of 48.2 emu/g signifying the cubic phase of copper ferrite, was obtained for sample quenched to liquid nitrogen temperature from 800 °C. The ethanol sensing response of the samples was studied and a maximum of 86% response was obtained for 500 ppm ethanol in the case of a furnace cooled sample calcined at 800 °C. The chemical sensing is seen to be correlated with the c/a ratio and is best in the case of tetragonal copper ferrite.

  7. Combustion-gas recirculation system

    Science.gov (United States)

    Baldwin, Darryl Dean

    2007-10-09

    A combustion-gas recirculation system has a mixing chamber with a mixing-chamber inlet and a mixing-chamber outlet. The combustion-gas recirculation system may further include a duct connected to the mixing-chamber inlet. Additionally, the combustion-gas recirculation system may include an open inlet channel with a solid outer wall. The open inlet channel may extend into the mixing chamber such that an end of the open inlet channel is disposed between the mixing-chamber inlet and the mixing-chamber outlet. Furthermore, air within the open inlet channel may be at a pressure near or below atmospheric pressure.

  8. Structural, magnetic and gas sensing properties of nanosized copper ferrite powder synthesized by sol gel combustion technique

    Energy Technology Data Exchange (ETDEWEB)

    Sumangala, T.P.; Mahender, C. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Barnabe, A. [Université de Toulouse, Institut Carnot CIRIMAT – UMR CNRS-UPS-INP 5085, Université Paul Sabatier, Toulouse 31062 (France); Venkataramani, N. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Prasad, Shiva, E-mail: shiva.pd@gmail.com [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2016-11-15

    Stoichiometric nano sized copper ferrite particles were synthesized by sol gel combustion technique. They were then calcined at various temperatures ranging from 300–800 °C and were either furnace cooled or quenched in liquid nitrogen. A high magnetisation value of 48.2 emu/g signifying the cubic phase of copper ferrite, was obtained for sample quenched to liquid nitrogen temperature from 800 °C. The ethanol sensing response of the samples was studied and a maximum of 86% response was obtained for 500 ppm ethanol in the case of a furnace cooled sample calcined at 800 °C. The chemical sensing is seen to be correlated with the c/a ratio and is best in the case of tetragonal copper ferrite. - Highlights: • One of the first study on ethanol sensing of cubic copper ferrite. • In-situ High temperature XRD done shows phase transition from cubic to tetragonal. • A non-monotonic increase in magnetization was seen with calcination temperature. • A response of 86% was obtained towards 500 ppm ethanol. • Tried to correlate sensing response and ion content in spinel structure.

  9. The effects of the location of Au additives on combustion-generated SnO(2) nanopowders for CO gas sensing.

    Science.gov (United States)

    Bakrania, Smitesh D; Wooldridge, Margaret S

    2010-01-01

    The current work presents the results of an experimental study of the effects of the location of gold additives on the performance of combustion-generated tin dioxide (SnO(2)) nanopowders in solid state gas sensors. The time response and sensor response to 500 ppm carbon monoxide is reported for a range of gold additive/SnO(2) film architectures including the use of colloidal, sputtered, and combustion-generated Au additives. The opportunities afforded by combustion synthesis to affect the SnO(2)/additive morphology are demonstrated. The best sensor performance in terms of sensor response (S) and time response (τ) was observed when the Au additives were restricted to the outermost layer of the gas-sensing film. Further improvement was observed in the sensor response and time response when the Au additives were dispersed throughout the outermost layer of the film, where S = 11.3 and τ = 51 s, as opposed to Au localized at the surface, where S = 6.1 and τ = 60 s.

  10. The Effects of the Location of Au Additives on Combustion-generated SnO2 Nanopowders for CO Gas Sensing

    Directory of Open Access Journals (Sweden)

    Smitesh D. Bakrania

    2010-07-01

    Full Text Available The current work presents the results of an experimental study of the effects of the location of gold additives on the performance of combustion-generated tin dioxide (SnO2 nanopowders in solid state gas sensors. The time response and sensor response to 500 ppm carbon monoxide is reported for a range of gold additive/SnO2 film architectures including the use of colloidal, sputtered, and combustion-generated Au additives. The opportunities afforded by combustion synthesis to affect the SnO2/additive morphology are demonstrated. The best sensor performance in terms of sensor response (S and time response (t was observed when the Au additives were restricted to the outermost layer of the gas-sensing film. Further improvement was observed in the sensor response and time response when the Au additives were dispersed throughout the outermost layer of the film, where S = 11.3 and t = 51 s, as opposed to Au localized at the surface, where S = 6.1 and t = 60 s.

  11. Flameless Combustion for Gas Turbines

    Science.gov (United States)

    Gutmark, Ephraim; Li, Guoqiang; Overman, Nick; Cornwell, Michael; Stankovic, Dragan; Fuchs, Laszlo; Milosavljevic, Vladimir

    2006-11-01

    An experimental study of a novel flameless combustor for gas turbine engines is presented. Flameless combustion is characterized by distributed flame and even temperature distribution for high preheat air temperature and large amount of recirculating low oxygen exhaust gases. Extremely low emissions of NOx, CO, and UHC are reported. Measurements of the flame chemiluminescence, CO and NOx emissions, acoustic pressure, temperature and velocity fields as a function of the preheat temperature, inlet air mass flow rate, exhaust nozzle contraction ratio, and combustor chamber diameter are described. The data indicate that larger pressure drop promotes flameless combustion and low NOx emissions at the same flame temperature. High preheated temperature and flow rates also help in forming stable combustion and therefore are favorable for flameless combustion.

  12. Assembly for directing combustion gas

    Energy Technology Data Exchange (ETDEWEB)

    Charron, Richard C.; Little, David A.; Snyder, Gary D.

    2016-04-12

    An arrangement is provided for delivering gases from a plurality of combustors of a can-annular gas turbine combustion engine to a first row of turbine blades including a first row of turbine blades. The arrangement includes a gas path cylinder, a cone and an integrated exit piece (IEP) for each combustor. Each IEP comprises an inlet chamber for receiving a gas flow from a respective combustor, and includes a connection segment. The IEPs are connected together to define an annular chamber extending circumferentially and concentric to an engine longitudinal axis, for delivering the gas flow to the first row of blades. A radiused joint extends radially inward from a radially outer side of the inlet chamber to an outer boundary of the annular chamber, and a flared fillet extends radially inward from a radially inner side of the inlet chamber to an inner boundary of the annular chamber.

  13. The Effects of the Location of Au Additives on Combustion-generated SnO2 Nanopowders for CO Gas Sensing

    OpenAIRE

    Bakrania, Smitesh D.; Margaret S. Wooldridge

    2010-01-01

    The current work presents the results of an experimental study of the effects of the location of gold additives on the performance of combustion-generated tin dioxide (SnO2) nanopowders in solid state gas sensors. The time response and sensor response to 500 ppm carbon monoxide is reported for a range of gold additive/SnO2 film architectures including the use of colloidal, sputtered, and combustion-generated Au additives. The opportunities afforded by combustion synthesis to affect the SnO2/a...

  14. A method of determining combustion gas flow

    Science.gov (United States)

    Bon Tempi, P. J.

    1968-01-01

    Zirconium oxide coating enables the determination of hot gas flow patterns on liquid rocket injector face and baffle surfaces to indicate modifications that will increase performance and improve combustion stability. The coating withstands combustion temperatures and due to the coarse surface and coloring of the coating, shows the hot gas patterns.

  15. Fuel gas combustion research at METC

    Energy Technology Data Exchange (ETDEWEB)

    Norton, T.S.

    1995-06-01

    The in-house combustion research program at METC is an integral part of many METC activities, providing support to METC product teams, project managers, and external industrial and university partners. While the majority of in-house combustion research in recent years has been focussed on the lean premixed combustion of natural gas fuel for Advanced Turbine Systems (ATS) applications, increasing emphasis is being placed on issues of syngas combustion, as the time approaches when the ATS and coal-fired power systems programs will reach convergence. When the METC syngas generator is built in 1996, METC will have the unique combination of mid-scale pressurized experimental facilities, a continuous syngas supply with variable ammonia loading, and a team of people with expertise in low-emissions combustion, chemical kinetics, combustion modeling, combustion diagnostics, and the control of combustion instabilities. These will enable us to investigate such issues as the effects of pressure, temperature, and fuel gas composition on the rate of conversion of fuel nitrogen to NOx, and on combustion instabilities in a variety of combustor designs.

  16. Key factors of combustion from kinetics to gas dynamics

    CERN Document Server

    Rubtsov, Nikolai M

    2017-01-01

    This book summarizes the main advances in the mechanisms of combustion processes. It focuses on the analysis of kinetic mechanisms of gas combustion processes and experimental investigation into the interrelation of kinetics and gas dynamics in gas combustion. The book is complimentary to the one previously published, The Modes of Gaseous Combustion.

  17. Torrefaction of empty fruit bunches under biomass combustion gas atmosphere.

    Science.gov (United States)

    Uemura, Yoshimitsu; Sellappah, Varsheta; Trinh, Thanh Hoai; Hassan, Suhaimi; Tanoue, Ken-Ichiro

    2017-06-13

    Torrefaction of oil palm empty fruit bunches (EFB) under combustion gas atmosphere was conducted in a batch reactor at 473, 523 and 573K in order to investigate the effect of real combustion gas on torrefaction behavior. The solid mass yield of torrefaction in combustion gas was smaller than that of torrefaction in nitrogen. This may be attributed to the decomposition enhancement effect by oxygen and carbon dioxide in combustion gas. Under combustion gas atmosphere, the solid yield for torrefaction of EFB became smaller as the temperature increased. The representative products of combustion gas torrefaction were carbon dioxide and carbon monoxide (gas phase) and water, phenol and acetic acid (liquid phase). By comparing torrefaction in combustion gas with torrefaction in nitrogen gas, it was found that combustion gas can be utilized as torrefaction gas to save energy and inert gas. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Decomposition of water into highly combustible hydroxyl gas used in ...

    African Journals Online (AJOL)

    Decomposition of water into highly combustible hydroxyl gas used in internal ... of alternative sources of energy that produce less amounts of carbon dioxide. ... The by-product obtained from combustion of this gas is water vapour and oxygen ...

  19. Combustion modeling in advanced gas turbine systems

    Energy Technology Data Exchange (ETDEWEB)

    Smoot, L.D.; Hedman, P.O.; Fletcher, T.H. [Brigham Young Univ., Provo, UT (United States)] [and others

    1995-10-01

    The goal of the U.S. Department of Energy`s Advanced Turbine Systems (ATS) program is to help develop and commercialize ultra-high efficiency, environmentally superior, and cost competitive gas turbine systems for base-load applications in the utility, independent power producer, and industrial markets. Combustion modeling, including emission characteristics, has been identified as a needed, high-priority technology by key professionals in the gas turbine industry.

  20. Combustion synthesis of LaFeO3 sensing nanomaterial

    Science.gov (United States)

    Zaza, F.; Pallozzi, V.; Serra, E.; Pasquali, M.

    2015-06-01

    Since industrial revolution, human activities drive towards unsustainable global economy due to the overexploitation of natural resources and the unacceptable emissions of pollution and greenhouse gases. In order to address that issue, engineering research has been focusing on gas sensors development for monitoring gas emissions and controlling the combustion process sustainability. Semiconductors metal oxides sensors are attractive technology because they require simple design and fabrication, involving high accessibility, small size and low cost. Perovskite oxides are the most promising sensing materials because sensitivity, selectivity, stability and speed-response can be modulated and optimized by changing the chemical composition. One of the most convenient synthesis process of perovskite is the citrate-nitrate auto-combustion method, in which nitrate is the oxidizing agent and citrate is the fuel and the chelating argent in the same time. Since the sensibility of perovskite oxides depends on the defective crystallographic structure and the nanomorphology, the experimental was designed in order to study the dependence of powder properties on the synthesis conditions, such as the solution acidity and the relative amount of metals, nitrates and citric acid. Crystalline structure was studied in depth for defining the effects of synthesis conditions on size, morphology and crystallographic structure of nanopowders of LaFeO3.

  1. Biomass combustion gas turbine CHP

    Energy Technology Data Exchange (ETDEWEB)

    Pritchard, D.

    2002-07-01

    This report summarises the results of a project to develop a small scale biomass combustor generating system using a biomass combustor and a micro-gas turbine indirectly fired via a high temperature heat exchanger. Details are given of the specification of commercially available micro-turbines, the manufacture of a biomass converter, the development of a mathematical model to predict the compatibility of the combustor and the heat exchanger with various compressors and turbines, and the utilisation of waste heat for the turbine exhaust.

  2. [Combustion temperature measurement of solid propellant by remote sensing FTIR].

    Science.gov (United States)

    Li, Yan; Wang, Jun-De; Sun, Xiu-Yun; Zhou, Xue-Tie

    2004-08-01

    The combustion temperature of solid propellant was measured in this paper. Emission spectra of the combustion flame were collected with remote sensing FTIR at the resolution of 4 cm(-1). The combustion temperatures with the burning time were calculated from the maximum spectral line intensity and the molecular rotation-vibration spectra of HF molecule, respectively. Combustion temperatures at each time were all 1 788.8 K from the maximum spectral line intensity method. For comparison, the temperatures calculated from the molecular rotation-vibration spectra were 1 859.7, 1 848. 3, 1 804.0 and 1 782.7 K, respectively. Results show that the two methods are all dependable in measuring combustion temperature of solid propellant. But the maximum spectral line intensity method is more convenient and rapid than the other when the combustion is relatively stable.

  3. Flow and Combustion in Advanced Gas Turbine Combustors

    CERN Document Server

    Janicka, Johannes; Schäfer, Michael; Heeger, Christof

    2013-01-01

    With regard to both the environmental sustainability and operating efficiency demands, modern combustion research has to face two main objectives, the optimization of combustion efficiency and the reduction of pollutants. This book reports on the combustion research activities carried out within the Collaborative Research Center (SFB) 568 “Flow and Combustion in Future Gas Turbine Combustion Chambers” funded by the German Research Foundation (DFG). This aimed at designing a completely integrated modeling and numerical simulation of the occurring very complex, coupled and interacting physico-chemical processes, such as turbulent heat and mass transport, single or multi-phase flows phenomena, chemical reactions/combustion and radiation, able to support the development of advanced gas turbine chamber concepts.

  4. Combustion heating value gas in a gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Kelsall, G. [CTDD, British Coal Corporation, Cheltenham (United Kingdom); Cannon, M. [European Gas Turbines Ltd., Lincoln (United Kingdom)

    1996-12-31

    Advanced coal and/or biomass based power generation systems offer the potential for high efficiency electricity generation with minimum environmental impact. An important component for many of these advanced power generation cycles is the gas turbine, for which development of a combustion system to burn low calorific value coal derived fuel gas, at turbine inlet temperatures of typically 1 100 - 1 260 deg C and with minimum pollutant emissions, is a key issue. A phased combustor development programme is under-way burning low calorific value fuel gas (3.6 - 4.1 MJ/m{sup 3}) with low emissions, particularly NO{sub x} derived from fuel-bound nitrogen. The first and second phases of the combustor development programme have been completed. The first phase used a generic tubo-annular, prototype combustor based on conventional design principles. Combustor performance for this first prototype combustor was encouraging. The second phase assessed five design variants of the prototype combustor, each variant achieving a progressive improvement in combustor performance. The operating conditions for this assessment were selected to represent a particular medium sized industrial gas turbine operating as part of an Air Blown Gasification Cycle (ABGC). The test conditions assessed therefore included the capability to operate the combustor using natural gas as a supplementary fuel, to suit one possible start-up procedure for the cycle. The paper presents a brief overview of the ABGC development initiative and discusses the general requirements for a gas turbine operating within such a cycle. In addition, it presents full combustor performance results for the second phase of turbine combustor development and discusses the rationale for the progressive design modifications made within that programme. The strategy for the further development of the combustor to burn low calorific value fuel gas with very low conversion of fuel-bound nitrogen to NO{sub x} is presented. (orig.) 6 refs.

  5. Experimental and CFD investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, Jimmy

    Reliable and accurate modeling capabilities for combustion systems are valuable tools for optimization of the combustion process. This work concerns primary precautions for reducing NO emissions, thereby abating the detrimental effects known as “acid rain”, and minimizing cost for flue gas...

  6. A Survey on Gas Sensing Technology

    Directory of Open Access Journals (Sweden)

    Huansheng Ning

    2012-07-01

    Full Text Available Sensing technology has been widely investigated and utilized for gas detection. Due to the different applicability and inherent limitations of different gas sensing technologies, researchers have been working on different scenarios with enhanced gas sensor calibration. This paper reviews the descriptions, evaluation, comparison and recent developments in existing gas sensing technologies. A classification of sensing technologies is given, based on the variation of electrical and other properties. Detailed introduction to sensing methods based on electrical variation is discussed through further classification according to sensing materials, including metal oxide semiconductors, polymers, carbon nanotubes, and moisture absorbing materials. Methods based on other kinds of variations such as optical, calorimetric, acoustic and gas-chromatographic, are presented in a general way. Several suggestions related to future development are also discussed. Furthermore, this paper focuses on sensitivity and selectivity for performance indicators to compare different sensing technologies, analyzes the factors that influence these two indicators, and lists several corresponding improved approaches.

  7. GAS TURBINE REHEAT USING IN SITU COMBUSTION

    Energy Technology Data Exchange (ETDEWEB)

    D.M. Bachovchin; T.E. Lippert; R.A. Newby P.G.A. Cizmas

    2004-05-17

    In situ reheat is an alternative to traditional gas turbine reheat design in which fuel is fed through airfoils rather than in a bulky discrete combustor separating HP and LP turbines. The goals are to achieve increased power output and/or efficiency without higher emissions. In this program the scientific basis for achieving burnout with low emissions has been explored. In Task 1, Blade Path Aerodynamics, design options were evaluated using CFD in terms of burnout, increase of power output, and possible hot streaking. It was concluded that Vane 1 injection in a conventional 4-stage turbine was preferred. Vane 2 injection after vane 1 injection was possible, but of marginal benefit. In Task 2, Combustion and Emissions, detailed chemical kinetics modeling, validated by Task 3, Sub-Scale Testing, experiments, resulted in the same conclusions, with the added conclusion that some increase in emissions was expected. In Task 4, Conceptual Design and Development Plan, Siemens Westinghouse power cycle analysis software was used to evaluate alternative in situ reheat design options. Only single stage reheat, via vane 1, was found to have merit, consistent with prior Tasks. Unifying the results of all the tasks, a conceptual design for single stage reheat utilizing 24 holes, 1.8 mm diameter, at the trailing edge of vane 1 is presented. A development plan is presented.

  8. Natural oscillations of a gas in an elongated combustion chamber

    Science.gov (United States)

    Nesterov, S. V.; Akulenko, L. D.; Baydulov, V. G.

    2017-02-01

    For the analysis of the frequencies and shapes of the natural oscillations of a gas in an elongated rectilinear combustion chamber, this chamber can be treated as a kind of an organ pipe that has the following specific features: 1. the chamber has an inlet and outlet nozzles; 2. a gas mixture burns in the combustion chamber; 3. the combustion materials flow out from the outlet nozzle; 4. the gas flows in such a way that its velocity in the larger part (closer to the outlet nozzle) of the chamber exceeds the speed of sound (Mach number M > 1). There are only separate domains (one or several), where M < 1. The excitation of the natural oscillations of the gas and an increase in the amplitude of such oscillations can lead to instability of the combustion process [1].

  9. Internal combustion engine for natural gas compressor operation

    Energy Technology Data Exchange (ETDEWEB)

    Hagen, Christopher; Babbitt, Guy

    2016-12-27

    This application concerns systems and methods for compressing natural gas with an internal combustion engine. In a representative embodiment, a method is featured which includes placing a first cylinder of an internal combustion engine in a compressor mode, and compressing a gas within the first cylinder, using the cylinder as a reciprocating compressor. In some embodiments a compression check valve system is used to regulate pressure and flow within cylinders of the engine during a compression process.

  10. Experimental and numerical investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, J.; Jensen, Peter Arendt; Meyer, K.E.

    2009-01-01

    tested the four-step global mechanism by Jones and Lindstedt (Combust. Flame 1988, 73, 233-249), and the 16 species and 41 reaction skeletal mechanism by Yang and Pope (Combust. Flame 1998, 112 16-32). The CFD model captured the main features of the combustion process and flow patterns. The application...... of more advanced chemical mechanisms did not improve the prediction of the overall combustion process but did provide additional information about species (especially H(2) and radicals), which is desirable for postprocessing pollutant formation.......Experimental data for velocity field, temperatures, and gas composition have been obtained from a 50 kW axisymmetric non-swirling natural gas fired combustion setup under two different settings. The reactor was constructed to simulate the conditions in the freeboard of a grate-fired boiler...

  11. A Survey on Gas Sensing Technology

    CERN Document Server

    Liu, Xiao; Liu, Hong; Hu, Sha; Zhang, Daqiang; Ning, Huansheng

    2013-01-01

    Sensing technology has been widely investigated and utilized for gas detection. Due to the different applicability and inherent limitations of different gas sensing technologies, researchers have been working on different scenarios with enhanced gas sensor calibration. This paper reviews the descriptions, evaluation, comparison and recent developments in existing gas sensing technologies. A classification of sensing technologies is given, based on the variation of electrical and other properties. Detailed introduction to sensing methods based on electrical variation is discussed through further classification according to sensing materials, including metal oxide semiconductors, polymers, carbon nanotubes, and moisture absorbing materials. Methods based on other kinds of variations such as optical, calorimetric, acoustic and gas-chromatographic, are presented in a general way. Several suggestions related to future development are also discussed. Furthermore, this paper focuses on sensitivity and selectivity fo...

  12. Gas Phase Sulfur, Chlorine and Potassium Chemistry in Biomass Combustion

    DEFF Research Database (Denmark)

    Løj, Lusi Hindiyarti

    2007-01-01

    conditions. These trace species contained in the biomass structure will be released to the gas phase during combustion and contribute to the problems generated during the process. The investigation during this PhD project is done to stepwise improve the understanding in the chemistry and reduce...... the uncertainties. In the present work, the detailed kinetic model for gas phase sulfur, chlorine, alkali metal, and their interaction has been updated. The K/O/H/Cl chemistry, S chemistry, and their interaction can reasonably predict a range of experimental data. In general, understanding of the interaction......Gas Phase Sulfur, Chlorine and Alkali Metal Chemistry in Biomass Combustion Concern about aerosols formation, deposits, corrosion, and gaseous emissions during biomass combustion, especially straw, continues to be a driving force for investigation on S, Cl, K-containing species under combustions...

  13. Distribution of combustible gas alarm based on embedded Ethernet technology

    Institute of Scientific and Technical Information of China (English)

    DING Xi-bo; ZHANG Jun-jie; WANG Yang

    2008-01-01

    One kind of combustible gas alarms based on industrial Ethernet was designed to prevent the gas leakage in industrial production sites. The alarm adopted the high performance microprocessor LPC2214 as the main chip. The embedded operating system μC/OS-Ⅱ and TCP/IP protocol stack ulP running on LPC2214 con-stitute a development platform of application of the combustible gas alarm. The test shows that it can automati-cally and continuously detect combustible gas in industrial production sites in several positions;it can give out sound-light alarm and take protective measures immediately against the gas leakage ; and it can send the detected data to PC through the Etheruet interface to realize the remote detection. The designed project provides a refer-ence to design industrial devices based on industrial Ethernet.

  14. Chemochromic Detector for Sensing Gas Leakage and Process for Producing the Same

    Science.gov (United States)

    Roberson, Luke B. (Inventor); Captain, Janine E. (Inventor); Williams, Martha K. (Inventor); Tate, LaNetra Clayton (Inventor)

    2015-01-01

    A chemochromic sensor for detecting a combustible gas, such as hydrogen, includes a chemochromic pigment and a textile polymer. The textile material includes a chemochromic pigment operably responsive to a combustible gas. The combustible gas sensing textile material can be made by melt spinning, solution spinning, or other similar techniques. In a preferred embodiment carbon nanotubes are used with the textile material which will increase the material strength and alter the thermal and/or electrical properties. These textiles woven into fabrics can provide garments not only with hydrogen sensing capabilities but the carbon nanotubes will allow for a range of sensing capabilities to be embedded (i.e. gas, health, and electronic monitors) within the garments.

  15. Graphene Hybrid Materials in Gas Sensing Applications

    Directory of Open Access Journals (Sweden)

    Usman Latif

    2015-12-01

    Full Text Available Graphene, a two dimensional structure of carbon atoms, has been widely used as a material for gas sensing applications because of its large surface area, excellent conductivity, and ease of functionalization. This article reviews the most recent advances in graphene hybrid materials developed for gas sensing applications. In this review, synthetic approaches to fabricate graphene sensors, the nano structures of hybrid materials, and their sensing mechanism are presented. Future perspectives of this rapidly growing field are also discussed.

  16. Metal oxide nanostructures as gas sensing devices

    CERN Document Server

    Eranna, G

    2011-01-01

    Metal Oxide Nanostructures as Gas Sensing Devices explores the development of an integrated micro gas sensor that is based on advanced metal oxide nanostructures and is compatible with modern semiconductor fabrication technology. This sensor can then be used to create a compact, low-power, handheld device for analyzing air ambience. The book first covers current gas sensing tools and discusses the necessity for miniaturized sensors. It then focuses on the materials, devices, and techniques used for gas sensing applications, such as resistance and capacitance variations. The author addresses th

  17. Nitrogen enriched combustion of a natural gas internal combustion engine to reduce NO.sub.x emissions

    Science.gov (United States)

    Biruduganti, Munidhar S.; Gupta, Sreenath Borra; Sekar, R. Raj; McConnell, Steven S.

    2008-11-25

    A method and system for reducing nitrous oxide emissions from an internal combustion engine. An input gas stream of natural gas includes a nitrogen gas enrichment which reduces nitrous oxide emissions. In addition ignition timing for gas combustion is advanced to improve FCE while maintaining lower nitrous oxide emissions.

  18. Gas turbine combustion performance test of hydrogen and carbon monoxide synthetic gas

    Energy Technology Data Exchange (ETDEWEB)

    Min Chul Lee; Seok Bin Seo; Jae Hwa Chung; Si Moon Kim; Yong Jin Joo; Dal Hong Ahn [Korea Electric Power Corporation, Daejeon (Republic of Korea). Green Growth Laboratory

    2010-07-15

    The development of coal IGCC (Integrated Gasification Combined Cycle) technology has made it possible to exploit electricity generated from coal at a low cost. Furthermore, IGCC is a pre-requisite for the development of CCS (Carbon Capture and Storage) technology and hydrogen generated from coal. To achieve the need to reduce CO{sub 2} emissions, Korea's 300 MW IGCC RDD&D (Research Development, Demonstration and Dissemination) project was launched in December 2006 under the leadership of the Korea Electric Power Corporation (KEPCO), with the support of the Korea Ministry of Knowledge Economy. When a new fuel is adapted to a gas turbine (such as syngas for IGCC), it is necessary to study the gas turbine combustion characteristics of the fuel, because gas turbines are very sensitive to its physical and chemical properties. This experimental study was conducted by investigating the combustion performance of synthetic gas, which is composed chiefly of hydrogen and carbon monoxide. The results of a test on synthetic gas combustion performance were compared with the results of methane combustion, which is a major component of natural gas. The results of the combustion test of both gases were examined in terms of the turbine's inlet temperature, combustion dynamics, emission characteristics, and flame structure. From the results of this experimental study, we were able to understand the combustion characteristics of synthetic gas and anticipate the problems when synthetic gas rather than natural gas is fuelled to a gas turbine. 21 refs., 11 figs., 1 tab.

  19. Fuel injection characteristics of diesel-stimulated natural gas combustion

    Energy Technology Data Exchange (ETDEWEB)

    Mbarawa, M.; Milton, B.E.; Casey, R.T.; Miao, H. [University of New South Wales, School of Mechanical and Manufacturing Engineering, Sydney, NSW (Australia)

    1999-07-01

    Although dual-fuel (DF) engines using a low cetane number primary fuel such as natural gas (NG) ignited by a pilot diesel spay have been the subject of much investigation over years, there are still many unknown problems related to the fundamental combustion process of two fuels. In this work, a quiescent constant volume combustion bomb and a 3-D numerical model have been used to study the effects of injection nozzle characteristics on the combustion of pre-mixed NG/air with pilot distillate spray. Experimental tests were conducted on combustion process of pre-mixed natural gas/air with pilot injection pressure of 30 and 20 MPa with a 4 hole injector, and also with injector nozzle of 8 and 4 holes. The global results obtained from computations compared well with the experimental results. (Author)

  20. Experimental and CFD investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, Jimmy

    treatment. The aim of this project is to provide validation data for Computational Fluid Dynamic (CFD) models relevant for grate firing combustion conditions. CFD modeling is a mathematical tool capable of predicting fluid flow, mixing and chemical reaction with thermal conversion and transport. Prediction......, but under well-defined conditions. Comprehensive experimental data for velocity field, temperatures, and gas composition are obtained from a 50 kW axisymmetric non-swirling natural gas fired combustion setup under two different settings. Ammonia is added to the combustion setup in order to simulate fuel...... of pollutant formation, which occurs in small concentrations with little impact on the general combustion process is in this work predicted by a post-processing step, making it less computationally expensive. A reactor was constructed to simulate the conditions in the freeboard of a grate fired boiler...

  1. Synthesis Gas from Pyrolysed Plastics for Combustion Engine

    Directory of Open Access Journals (Sweden)

    Chríbik Andrej

    2015-12-01

    Full Text Available The article discusses the application of synthesis gas from pyrolysis of plastics in petrol engine. The appropriate experimental measurements were performed on a combustion engine LGW 702 designated for micro-cogeneration unit. The power parameters, economic and internal parameters of the engine were compared to the engine running on the reference fuel - natural gas and synthesis gas. Burning synthesis gas leads to decreased performance by about 5% and to increased mass hourly consumption by 120%. In terms of burning, synthesis gas has similar properties as natural gas. More significant changes are observed in even burning of fuel in consecutive cycles.

  2. Modelling combustion reactions for gas flaring and its resulting emissions

    Directory of Open Access Journals (Sweden)

    O. Saheed Ismail

    2016-07-01

    Full Text Available Flaring of associated petroleum gas is an age long environmental concern which remains unabated. Flaring of gas maybe a very efficient combustion process especially steam/air assisted flare and more economical than utilization in some oil fields. However, it has serious implications for the environment. This study considered different reaction types and operating conditions for gas flaring. Six combustion equations were generated using the mass balance concept with varying air and combustion efficiency. These equations were coded with a computer program using 12 natural gas samples of different chemical composition and origin to predict the pattern of emission species from gas flaring. The effect of key parameters on the emission output is also shown. CO2, CO, NO, NO2 and SO2 are the anticipated non-hydrocarbon emissions of environmental concern. Results show that the quantity and pattern of these chemical species depended on percentage excess/deficiency of stoichiometric air, natural gas type, reaction type, carbon mass content, impurities, combustion efficiency of the flare system etc. These emissions degrade the environment and human life, so knowing the emission types, pattern and flaring conditions that this study predicts is of paramount importance to governments, environmental agencies and the oil and gas industry.

  3. Internal Combustion Engine Powered by Synthesis Gas from Pyrolysed Plastics

    Directory of Open Access Journals (Sweden)

    Chríbik Andrej

    2016-07-01

    Full Text Available The article discusses the application of synthesis gas from pyrolysis of plastics in petrol engine. The appropriate experimental measurements were performed on a combustion engine LGW 702 designated for micro-cogeneration unit. The power parameters, economic parameters in term of brake specific fuel consumption, and internal parameters of the engine were compared to the engine running on the reference fuel - natural gas and synthesis gas. Burning synthesis gas leads to decreased performance by about 5% and to increased mass hourly consumption by 120 %. In terms of burning, synthesis gas has similar properties as natural gas. Compared with [5] a more detailed study has been prepared on the effects of angle of spark advance on the engine torque, giving more detailed assessment of engine cycle variability and considering specification of start and end of combustion in the logarithm p-V diagram.

  4. Thermo-Gas Dynamics of Hydrogen Combustion and Explosion

    CERN Document Server

    Gelfand, Boris E; Medvedev, Sergey P; Khomik, Sergey V

    2012-01-01

    The potential of hydrogen as an important future energy source has generated fresh interest in the study of hydrogenous gas mixtures. Indeed, both its high caloricity and reactivity are unique properties, the latter underscoring safety considerations when handling such mixtures.   The present monograph is devoted to the various aspects of hydrogen combustion and explosion processes. In addition to theoretical and phenomenological considerations, this work also collates the results of many experiments from less well known sources. The text reviews the literature in this respect, thereby providing valuable information about the thermo-gas-dynamical parameters of combustion processes for selected experimental settings in a range of scientific and industrial applications.

  5. A Simple Practical Method for Calculating the Calorimetric Properties of Combustion Gas

    OpenAIRE

    1980-01-01

    The simplified formulae are proposed for the enthalpy and the entropy of combustion gas constituents, by treating each gas constituent as semi-ideal gas. Based on these formulae, there is shown the practical method for calculating directly the calorimetric properties of combustion gas and the adiabatic combustion temperature. This method allows one to analyse the heat processes of combustion gas within the error approvable for practical use and also with practical simplicity. Some calculated ...

  6. CFD simulation of gas and particles combustion in biomass furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Griselin, Nicolas

    2000-11-01

    In this thesis, gas and particle combustion in biomass furnaces is investigated numerically. The aim of this thesis is to use Computational Fluid Dynamics (CFD) technology as an effective computer based simulation tool to study and develop the combustion processes in biomass furnaces. A detailed model for the numerical simulation of biomass combustion in a furnace, including fixed-bed modeling, gas-phase calculation (species distribution, temperature field, flow field) and gas-solid two-phase interaction for flying burning particles is presented. This model is used to understand the mechanisms of combustion and pollutant emissions under different conditions in small scale and large scale furnaces. The code used in the computations was developed at the Division of Fluid Mechanics, LTH. The flow field in the combustion enclosure is calculated by solving the Favre-averaged Navier-Stokes equations, with standard {kappa} - {epsilon} turbulence closure, together with the energy conservation equation and species transport equations. Discrete transfer method is used for calculating the radiation source term in the energy conservation equation. Finite difference is used to solve the general form of the equation yielding solutions for gas-phase temperatures, velocities, turbulence intensities and species concentrations. The code has been extended through this work in order to include two-phase flow simulation of particles and gas combustion. The Favre-averaged gas equations are solved in a Eulerian framework while the submodels for particle motion and combustion are used in the framework of a Lagrangian approach. Numerical simulations and measurement data of unburned hydrocarbons (UHC), CO, H{sub 2}, O{sub 2} and temperature on the top of the fixed bed are used to model the amount of tar and char formed during pyrolysis and combustion of biomass fuel in the bed. Different operating conditions are examined. Numerical calculations are compared with the measured data. It is

  7. Gas sensing in 2D materials

    Science.gov (United States)

    Yang, Shengxue; Jiang, Chengbao; Wei, Su-huai

    2017-06-01

    Two-dimensional (2D) layered inorganic nanomaterials have attracted huge attention due to their unique electronic structures, as well as extraordinary physical and chemical properties for use in electronics, optoelectronics, spintronics, catalysts, energy generation and storage, and chemical sensors. Graphene and related layered inorganic analogues have shown great potential for gas-sensing applications because of their large specific surface areas and strong surface activities. This review aims to discuss the latest advancements in the 2D layered inorganic materials for gas sensors. We first elaborate the gas-sensing mechanisms and introduce various types of gas-sensing devices. Then, we describe the basic parameters and influence factors of the gas sensors to further enhance their performance. Moreover, we systematically present the current gas-sensing applications based on graphene, graphene oxide (GO), reduced graphene oxide (rGO), functionalized GO or rGO, transition metal dichalcogenides, layered III-VI semiconductors, layered metal oxides, phosphorene, hexagonal boron nitride, etc. Finally, we conclude the future prospects of these layered inorganic materials in gas-sensing applications.

  8. Real gas CFD simulations of hydrogen/oxygen supercritical combustion

    Science.gov (United States)

    Pohl, S.; Jarczyk, M.; Pfitzner, M.; Rogg, B.

    2013-03-01

    A comprehensive numerical framework has been established to simulate reacting flows under conditions typically encountered in rocket combustion chambers. The model implemented into the commercial CFD Code ANSYS CFX includes appropriate real gas relations based on the volume-corrected Peng-Robinson (PR) equation of state (EOS) for the flow field and a real gas extension of the laminar flamelet combustion model. The results indicate that the real gas relations have a considerably larger impact on the flow field than on the detailed flame structure. Generally, a realistic flame shape could be achieved for the real gas approach compared to experimental data from the Mascotte test rig V03 operated at ONERA when the differential diffusion processes were only considered within the flame zone.

  9. Scaling study of the combustion performance of gas-gas rocket injectors

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Wei; Cai Guo-Biao; Jin Ping

    2011-01-01

    To obtain the key subelements that may influence the scaling of gas-gas injector combustor performance,the combustion performance subelements in a liquid propellant rocket engine combustor are initially analysed based on the results of a previous study on the scaling of a gas-gas combustion flowfield.Analysis indicates that inner wall friction loss and heat-flux loss are two key issues in gaining the scaling criterion of the combustion performance.The similarity conditions of the inner wall friction loss and heat-flux loss in a gas-gas combustion chamber are obtained by theoretical analyses.Then the theoretical scaling criterion was obtained for the combustion performance,but it proved to be impractical.The criterion conditions,the wall friction and the heat flux are further analysed in detail to obtain the specific engineering scaling criterion of the combustion performance.The results indicate that when the inner flowfields in the combustors are similar,the combustor wall shear stress will have similar distributions qualitatively and will be directly proportional to pc08dt-0.2 quantitatively.In addition,the combustion peformance will remain unchanged.Furthermore,multi-element injector chambers with different geometric sizes and at different pressures are numerically simulated and the wall shear stress and combustion efficiencies are solved and compared with each other.A multielement injector chamber is designed and hot-fire tested at several chamber pressures and the combustion performances are measured in a total of nine hot-fire tests.The numerical and experimental results verified the similarities among combustor wall shear stress and combustion performances at different chamber pressures and geometries,with the criterion applied.

  10. Condensed phase decomposition and gas phase combustion of hydrazinium nitroformate

    NARCIS (Netherlands)

    Dragomir, O.E.; Tummers, M.J.; Veen, E.H. van; Heijden, A.E.D.M. van der; Roekaerts, D.J.E.M.

    2009-01-01

    This paper presents the results of a series of experiments on the condensed phase decomposition and the gas phase combustion of hydrazinium nitroformate (HNF). The experiments include SEM analysis of quenched samples that showed evidence of the formation of a foam layer. FTIR spectrometry and mass s

  11. Enhanced efficiency of internal combustion engines by employing spinning gas.

    Science.gov (United States)

    Geyko, V I; Fisch, N J

    2014-08-01

    The efficiency of the internal combustion engine might be enhanced by employing spinning gas. A gas spinning at near sonic velocities has an effectively higher heat capacity, which allows practical fuel cycles, which are far from the Carnot efficiency, to approach more closely the Carnot efficiency. A remarkable gain in fuel efficiency is shown to be theoretically possible for the Otto and Diesel cycles. The use of a flywheel, in principle, could produce even greater increases in efficiency.

  12. Enhanced efficiency of internal combustion engines by employing spinning gas

    Science.gov (United States)

    Geyko, V. I.; Fisch, N. J.

    2014-08-01

    The efficiency of the internal combustion engine might be enhanced by employing spinning gas. A gas spinning at near sonic velocities has an effectively higher heat capacity, which allows practical fuel cycles, which are far from the Carnot efficiency, to approach more closely the Carnot efficiency. A remarkable gain in fuel efficiency is shown to be theoretically possible for the Otto and Diesel cycles. The use of a flywheel, in principle, could produce even greater increases in efficiency.

  13. Gas-sensing properties of nanocomplex metal oxide

    Institute of Scientific and Technical Information of China (English)

    CHEN Liangyuan; HE Zhusheng; YAN Tao; BAI Shouli; CHEN Aifan; LIU Chung Chiun

    2005-01-01

    The development of CuO/CeO2 nanocomposites as the sensing material of semiconductor gas sensors is reported.CuO/CeO2 nanocomplex oxide is prepared by modified sol-gel method that uses copper nitrate, cerium nitrate and ethylene glycol as precursors. The optimized synthesis parameters and processing condition have been established. The particle size and distribution, phase morphology, specific surface, electronic states of atoms and gas sensing properties have been systematically characterized by Transmission Electron Microscope (TEM), Brunauer Emmett Teller (BET), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and gas sensitivity measurement. The results show that the sensor sensitivity depends on particle size, Cu/Ce cation ratio and calcination temperature. The effects of calcinations temperature and CuO loading on the gas sensitivity are also examined. The optimum calcination temperature and the CuO content for the highest sensitivity are 600 ℃ and 12%, respectively. The combination of excellent thermal stability.and tunable sensing properties through careful control of the processing parameters and selection of material composition gives rise to novel nanocomposites attractive to the sensitive and selective detection of a variety of toxic and combustible gases.

  14. Compounded turbocharged rotary internal combustion engine fueled with natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, P.E.

    1992-10-15

    This patent describes a compounded engine. It comprises: a first Wankel engine having a housing with a trochoidal inner surface containing a generally triangular shaped rotor, the engine containing a fuel supply system suitable for operating the engine with natural gas as a fuel; a turbocharge compressing air for combustion by the engine, the turbocharger being driven by the exhaust gases which exit from the engine; a combustion chamber in fluid communication with the exhaust from the engine after that exhaust has passed through the turbocharger, the chamber having an ignition device suitable for igniting hydrocarbons in the engine exhaust, whereby the engine timing, and the air and fuel mixture of the engine are controlled so that when the engine exhaust reaches the combustion chamber the exhaust contains a sufficient amount of oxygen and hydrocarbons to enable ignition and combustion of the engine exhaust in the combustion chamber without the addition of fuel or air, and whereby the engine operating conditions are controlled to vary the performance of the secondary combustor; and a controllable ignition device to ignite the exhaust gases in the combustion chamber at predetermined times.

  15. Advanced modeling of oxy-fuel combustion of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Chungen Yin

    2011-01-15

    The main goal of this small-scale project is to investigate oxy-combustion of natural gas (NG) through advanced modeling, in which radiation, chemistry and mixing will be reasonably resolved. 1) A state-of-the-art review was given regarding the latest R and D achievements and status of oxy-fuel technology. The modeling and simulation status and achievements in the field of oxy-fuel combustion were also summarized; 2) A computer code in standard c++, using the exponential wide band model (EWBM) to evaluate the emissivity and absorptivity of any gas mixture at any condition, was developed and validated in detail against data in literature. A new, complete, and accurate WSGGM, applicable to both air-fuel and oxy-fuel combustion modeling and applicable to both gray and non-gray calculation, was successfully derived, by using the validated EWBM code as the reference mode. The new WSGGM was implemented in CFD modeling of two different oxy-fuel furnaces, through which its great, unique advantages over the currently most widely used WSGGM were demonstrated. 3) Chemical equilibrium calculations were performed for oxy-NG flame and air-NG flame, in which dissociation effects were considered to different degrees. Remarkable differences in oxy-fuel and air-fuel combustion were revealed, and main intermediate species that play key roles in oxy-fuel flames were identified. Different combustion mechanisms are compared, e.g., the most widely used 2-step global mechanism, refined 4-step global mechanism, a global mechanism developed for oxy-fuel using detailed chemical kinetic modeling (CHEMKIN) as reference. 4) Over 15 CFD simulations were done for oxy-NG combustion, in which radiation, chemistry, mixing, turbulence-chemistry interactions, and so on were thoroughly investigated. Among all the simulations, RANS combined with 2-step and refined 4-step mechanism, RANS combined with CHEMKIN-based new global mechanism for oxy-fuel modeling, and LES combined with different combustion

  16. Low temperature catalytic combustion of natural gas - hydrogen - air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Newson, E.; Roth, F. von; Hottinger, P.; Truong, T.B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The low temperature catalytic combustion of natural gas - air mixtures would allow the development of no-NO{sub x} burners for heating and power applications. Using commercially available catalysts, the room temperature ignition of methane-propane-air mixtures has been shown in laboratory reactors with combustion efficiencies over 95% and maximum temperatures less than 700{sup o}C. After a 500 hour stability test, severe deactivation of both methane and propane oxidation functions was observed. In cooperation with industrial partners, scaleup to 3 kW is being investigated together with startup dynamics and catalyst stability. (author) 3 figs., 3 refs.

  17. The Combination of Internal-Combustion Engine and Gas Turbine

    Science.gov (United States)

    Zinner, K.

    1947-01-01

    While the gas turbine by itself has been applied in particular cases for power generation and is in a state of promising development in this field, it has already met with considerable success in two cases when used as an exhaust turbine in connection with a centrifugal compressor, namely, in the supercharging of combustion engines and in the Velox process, which is of particular application for furnaces. In the present paper the most important possibilities of combining a combustion engine with a gas turbine are considered. These "combination engines " are compared with the simple gas turbine on whose state of development a brief review will first be given. The critical evaluation of the possibilities of development and fields of application of the various combustion engine systems, wherever it is not clearly expressed in the publications referred to, represents the opinion of the author. The state of development of the internal-combustion engine is in its main features generally known. It is used predominantly at the present time for the propulsion of aircraft and road vehicles and, except for certain restrictions due to war conditions, has been used to an increasing extent in ships and rail cars and in some fields applied as stationary power generators. In the Diesel engine a most economical heat engine with a useful efficiency of about 40 percent exists and in the Otto aircraft engine a heat engine of greatest power per unit weight of about 0.5 kilogram per horsepower.

  18. Internal combustion engine for natural gas compressor operation

    Energy Technology Data Exchange (ETDEWEB)

    Hagen, Christopher L.; Babbitt, Guy; Turner, Christopher; Echter, Nick; Weyer-Geigel, Kristina

    2016-04-19

    This application concerns systems and methods for compressing natural gas with an internal combustion engine. In a representative embodiment, a system for compressing a gas comprises a reciprocating internal combustion engine including at least one piston-cylinder assembly comprising a piston configured to travel in a cylinder and to compress gas in the cylinder in multiple compression stages. The system can further comprise a first pressure tank in fluid communication with the piston-cylinder assembly to receive compressed gas from the piston-cylinder assembly until the first pressure tank reaches a predetermined pressure, and a second pressure tank in fluid communication with the piston-cylinder assembly and the first pressure tank. The second pressure tank can be configured to receive compressed gas from the piston-cylinder assembly until the second pressure tank reaches a predetermined pressure. When the first and second pressure tanks have reached the predetermined pressures, the first pressure tank can be configured to supply gas to the piston-cylinder assembly, and the piston can be configured to compress the gas supplied by the first pressure tank such that the compressed gas flows into the second pressure tank.

  19. Internal combustion engine for natural gas compressor operation

    Science.gov (United States)

    Hagen, Christopher L.; Babbitt, Guy; Turner, Christopher; Echter, Nick; Weyer-Geigel, Kristina

    2016-04-19

    This application concerns systems and methods for compressing natural gas with an internal combustion engine. In a representative embodiment, a system for compressing a gas comprises a reciprocating internal combustion engine including at least one piston-cylinder assembly comprising a piston configured to travel in a cylinder and to compress gas in the cylinder in multiple compression stages. The system can further comprise a first pressure tank in fluid communication with the piston-cylinder assembly to receive compressed gas from the piston-cylinder assembly until the first pressure tank reaches a predetermined pressure, and a second pressure tank in fluid communication with the piston-cylinder assembly and the first pressure tank. The second pressure tank can be configured to receive compressed gas from the piston-cylinder assembly until the second pressure tank reaches a predetermined pressure. When the first and second pressure tanks have reached the predetermined pressures, the first pressure tank can be configured to supply gas to the piston-cylinder assembly, and the piston can be configured to compress the gas supplied by the first pressure tank such that the compressed gas flows into the second pressure tank.

  20. Apparatus and method for gas turbine active combustion control system

    Science.gov (United States)

    Umeh, Chukwueloka (Inventor); Kammer, Leonardo C. (Inventor); Shah, Minesh (Inventor); Fortin, Jeffrey B. (Inventor); Knobloch, Aaron (Inventor); Myers, William J. (Inventor); Mancini, Alfred Albert (Inventor)

    2011-01-01

    An Active Combustion Control System and method provides for monitoring combustor pressure and modulating fuel to a gas turbine combustor to prevent combustion dynamics and/or flame extinguishments. The system includes an actuator, wherein the actuator periodically injects pulsed fuel into the combustor. The apparatus also includes a sensor connected to the combustion chamber down stream from an inlet, where the sensor generates a signal detecting the pressure oscillations in the combustor. The apparatus controls the actuator in response to the sensor. The apparatus prompts the actuator to periodically inject pulsed fuel into the combustor at a predetermined sympathetic frequency and magnitude, thereby controlling the amplitude of the pressure oscillations in the combustor by modulating the natural oscillations.

  1. Prediction and control of combustion instabilities in industrial gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Kelsall, G. [ALSTOM Power Technology Centre, Leicester (United Kingdom); Troger, C. [ALSTOM Power Sweden AB, Finspaang (Sweden)

    2004-08-01

    A key enabling technology for highly efficient gas turbines, with low emissions of nitrogen oxides, is the suppression and control of combustion induced thermoacoustic instabilities. This will require an improved understanding of the phenomena governing these instabilities. A multi-partner project, funded in part by the European Commission, has been set up to address this requirement. Known as Preccinsta, the project has the overall aims of: Investigation of the physics, prediction and control of combustor instabilities. This will lead to the development of validated predictive tools and the development of design rules to avoid such instabilities. These advanced techniques will help to design new combustors for gas turbines with improved efficiency, reliability and availability. Investigation of the ability of industrial gas turbines to burn a wider range of fuels such as biomass and waste derived fuels. This paper gives an overview of the development of techniques to understand and control combustion instabilities in industrial gas turbines. It also presents some of the results achieved within the first two years of the project, focusing on passive damping and burner characterisation for an annular combustion system. These topics demonstrate the excellent interaction of analytical modelling and experimental testing within the project. (author)

  2. Correlating defect induced ferromagnetism and gas sensing properties of undoped tin oxide sensors

    Science.gov (United States)

    Kamble, Vinayak B.; Umarji, Arun M.

    2014-06-01

    A correlation between gas sensing properties and defect induced Room Temperature Ferromagnetism (RTFM) is demonstrated in non-stoichiometric SnO2 prepared by solution combustion method. The presence of oxygen vacancies (VO), confirmed by RTFM is identified as the primary factor for enhanced gas sensing effect. The as-prepared SnO2 shows high saturation magnetization of ˜0.018 emu/g as compared to ˜0.002 and ˜0.0005 emu/g in annealed samples and SnO2 prepared by precipitation respectively. The SnO2 prepared by precipitation which is an equilibrium method of synthesis shows lesser defects compared to the combustion product and hence exhibits lesser sensitivity in spite of smaller crystallite size. The study utilizes RTFM as a potential tool to characterize metal oxide gas sensors and recognizes the significance of oxygen vacancies in sensing mechanism over the microstructure.

  3. Combustion of coal gas fuels in a staged combustor

    Science.gov (United States)

    Rosfjord, T. J.; Mcvey, J. B.; Sederquist, R. A.; Schultz, D. F.

    1982-01-01

    Gaseous fuels produced from coal resources generally have heating values much lower than natural gas; the low heating value could result in unstable or inefficient combustion. Coal gas fuels may contain ammonia which if oxidized in an uncontrolled manner could result in unacceptable nitrogen oxide exhaust emission levels. Previous investigations indicate that staged, rich-lean combustion represents a desirable approach to achieve stable, efficient, low nitrogen oxide emission operation for coal-derived liquid fuels contaning up to 0.8-wt pct nitrogen. An experimental program was conducted to determine whether this fuel tolerance can be extended to include coal-derived gaseous fuels. The results of tests with three nitrogen-free fuels having heating values of 100, 250, and 350 Btu/scf and a 250 Btu/scf heating value doped to contain 0.7 pct ammonia are presented.

  4. Feasibility of pulse combustion in micro gas turbines

    Science.gov (United States)

    Honkatukia, Juha; Saari, Esa; Knuuttila, Timo; Larjola, Jaakko; Backman, Jari

    2012-10-01

    In gas turbines, a fast decrease of efficiency appears when the output decreases; the efficiency of a large gas turbine (20...30 MW) is in the order of 40 %, the efficiency of a 30 kW gas turbine with a recuperator is in the order of 25 %, but the efficiency of a very small gas turbine (2...6 kW) in the order of 4...6 % (or 8...12 % with an optimal recuperator). This is mainly a result of the efficiency decrease in kinetic compressors, due to the Reynolds number effect. Losses in decelerating flow in a flow passage are sensitive to the Reynolds number effects. In contrary to the compression, the efficiency of expansion in turbines is not so sensitive to the Reynolds number; very small turbines are made with rather good efficiency because the flow acceleration stabilizes the boundary layer. This study presents a system where the kinetic compressor of a gas turbine is replaced with a pulse combustor. The combustor is filled with a combustible gas mixture, ignited, and the generated high pressure gas is expanded in the turbine. The process is repeated frequently, thus producing a pulsating flow to the turbine; or almost a uniform flow, if several parallel combustors are used and triggered alternately in a proper way. Almost all the compression work is made by the temperature increase from the combustion. This gas turbine type is investigated theoretically and its combustor also experimentally with the conclusion that in a 2 kW power size, the pulse flow gas turbine is not as attractive as expected due to the big size and weight of parallel combustors and due to the efficiency being in the order of 8 % to 10 %. However, in special applications having a very low power demand, below 1000 W, this solution has better properties when compared to the conventional gas turbine and it could be worth of a more detailed investigation.

  5. Nanocomposite thin films for optical gas sensing

    Science.gov (United States)

    Ohodnicki, Paul R; Brown, Thomas D

    2014-06-03

    The disclosure relates to a plasmon resonance-based method for gas sensing in a gas stream utilizing a gas sensing material. In an embodiment the gas stream has a temperature greater than about 500.degree. C. The gas sensing material is comprised of gold nanoparticles having an average nanoparticle diameter of less than about 100 nanometers dispersed in an inert matrix having a bandgap greater than or equal to 5 eV, and an oxygen ion conductivity less than approximately 10.sup.-7 S/cm at a temperature of 700.degree. C. Exemplary inert matrix materials include SiO.sub.2, Al.sub.2O.sub.3, and Si.sub.3N.sub.4 as well as modifications to modify the effective refractive indices through combinations and/or doping of such materials. Changes in the chemical composition of the gas stream are detected by changes in the plasmon resonance peak. The method disclosed offers significant advantage over active and reducible matrix materials typically utilized, such as yttria-stabilized zirconia (YSZ) or TiO.sub.2.

  6. Flashback mechanisms in lean premixed gas turbine combustion

    CERN Document Server

    Benim, Ali Cemal

    2014-01-01

    Blending fuels with hydrogen offers the potential to reduce NOx and CO2 emissions in gas turbines, but doing so introduces potential new problems such as flashback.  Flashback can lead to thermal overload and destruction of hardware in the turbine engine, with potentially expensive consequences. The little research on flashback that is available is fragmented. Flashback Mechanisms in Lean Premixed Gas Turbine Combustion by Ali Cemal Benim will address not only the overall issue of the flashback phenomenon, but also the issue of fragmented and incomplete research.Presents a coherent review of f

  7. Combustion synthesis of LaFeO{sub 3} sensing nanomaterial

    Energy Technology Data Exchange (ETDEWEB)

    Zaza, F., E-mail: fabio.zaza@enea.it; Serra, E. [ENEA-Casaccia Research Centre, Via Anguillarese 301, 00123 Rome (Italy); Pallozzi, V.; Pasquali, M. [Department of Basic and Applied Sciences for Engineering, La Sapienza University, Via A. Scarpa 14/16, 00161 Rome (Italy)

    2015-06-23

    Since industrial revolution, human activities drive towards unsustainable global economy due to the overexploitation of natural resources and the unacceptable emissions of pollution and greenhouse gases. In order to address that issue, engineering research has been focusing on gas sensors development for monitoring gas emissions and controlling the combustion process sustainability. Semiconductors metal oxides sensors are attractive technology because they require simple design and fabrication, involving high accessibility, small size and low cost. Perovskite oxides are the most promising sensing materials because sensitivity, selectivity, stability and speed-response can be modulated and optimized by changing the chemical composition. One of the most convenient synthesis process of perovskite is the citrate-nitrate auto-combustion method, in which nitrate is the oxidizing agent and citrate is the fuel and the chelating argent in the same time. Since the sensibility of perovskite oxides depends on the defective crystallographic structure and the nanomorphology, the experimental was designed in order to study the dependence of powder properties on the synthesis conditions, such as the solution acidity and the relative amount of metals, nitrates and citric acid. Crystalline structure was studied in depth for defining the effects of synthesis conditions on size, morphology and crystallographic structure of nanopowders of LaFeO{sub 3}.

  8. Soft sensing for gas-lift wells

    NARCIS (Netherlands)

    Bloemen, H.H.J.; Belfroid, S.P.C.; Sturm, W.L.; Verhelst, F.J.P.C.M.G.

    2006-01-01

    This paper considers the use of extended Kalman filtering as a soft-sensing technique for gas lift wells. This technique is deployed for the estimation of dynamic variables that are not directly measured. Possible applications are the estimation of flow rates from surface and downhole pressure measu

  9. Thermal explosion in a combustible gas containing fuel droplets

    Science.gov (United States)

    McIntosh, A. C.; Gol'dshtein, V.; Goldfarb, I.; Zinoviev, A.

    1998-06-01

    An original physical model of self-ignition in a combustible gas mixture containing liquid fuel droplets is developed. The droplets are small enough for the gas-droplet mixture to be considered as a fine mist such that individual droplet burning is subsumed into a well-stirred, spatially invariant burning approximation. A classical Semenov-type analysis is used to describe the exothermic reaction, and the endothermic terms involve the use of quasi-steady mass transfer/heat balance and the Clausius-Clapeyron evaporative law. The resulting analysis predicts the ignition delay which is a function of the system parameters. Results are given for typical dynamical regimes. The case of different initial temperatures for droplets and gas is highly relevant to gas turbine lean blow-out and re-ignition.

  10. Natural Gas for Advanced Dual-Fuel Combustion Strategies

    Science.gov (United States)

    Walker, Nicholas Ryan

    Natural gas fuels represent the next evolution of low-carbon energy feedstocks powering human activity worldwide. The internal combustion engine, the energy conversion device widely used by society for more than one century, is capable of utilizing advanced combustion strategies in pursuit of ultra-high efficiency and ultra-low emissions. Yet many emerging advanced combustion strategies depend upon traditional petroleum-based fuels for their operation. In this research the use of natural gas, namely methane, is applied to both conventional and advanced dual-fuel combustion strategies. In the first part of this work both computational and experimental studies are undertaken to examine the viability of utilizing methane as the premixed low reactivity fuel in reactivity controlled compression ignition, a leading advanced dual-fuel combustion strategy. As a result, methane is shown to be capable of significantly extending the load limits for dual-fuel reactivity controlled compression ignition in both light- and heavy-duty engines. In the second part of this work heavy-duty single-cylinder engine experiments are performed to research the performance of both conventional dual-fuel (diesel pilot ignition) and advanced dual-fuel (reactivity controlled compression ignition) combustion strategies using methane as the premixed low reactivity fuel. Both strategies are strongly influenced by equivalence ratio; diesel pilot ignition offers best performance at higher equivalence ratios and higher premixed methane ratios, whereas reactivity controlled compression ignition offers superior performance at lower equivalence ratios and lower premixed methane ratios. In the third part of this work experiments are performed in order to determine the dominant mode of heat release for both dual-fuel combustion strategies. By studying the dual-fuel homogeneous charge compression ignition and single-fuel spark ignition, strategies representative of autoignition and flame propagation

  11. New combustion, environment regulations: the answers for natural gas; Nouvelles reglementations, combustion, environnement: les reponses pour le gaz naturel

    Energy Technology Data Exchange (ETDEWEB)

    Le Peltier-Marc, A. [Gaz de France (GDF), 75 - Paris (France)

    1997-12-31

    This paper reports on the point of view from Gaz de France (GdF) company concerning the potential consequences of the use of natural gas in combustion systems with respect to the new regulations about combustion and environment. Details concerning the measures relative to the limitation of pollutants in small combustion installations (2 - 20 MW) are given (chimney height, SO{sub x}, NO{sub x} and dusts content in exhaust gases). (J.S.)

  12. Nanostructure Sensing and Transmission of Gas Data

    Science.gov (United States)

    Li, Jing (Inventor)

    2011-01-01

    A system for receiving, analyzing and communicating results of sensing chemical and/or physical parameter values, using wireless transmission of the data. Presence or absence of one or more of a group of selected chemicals in a gas or vapor is determined, using suitably functionalized carbon nanostructures that are exposed to the gas. One or more physical parameter values, such as temperature, vapor pressure, relative humidity and distance from a reference location, are also sensed for the gas, using nanostructures and/or microstructures. All parameter values are transmitted wirelessly to a data processing site or to a control site, using an interleaving pattern for data received from different sensor groups, using I.E.E.E. 802.11 or 802.15 protocol, for example. Methods for estimating chemical concentration are discussed.

  13. Surface studies of gas sensing metal oxides.

    Science.gov (United States)

    Batzill, Matthias; Diebold, Ulrike

    2007-05-21

    The relation of surface science studies of single crystal metal oxides to gas sensing applications is reviewed. Most metal oxide gas sensors are used to detect oxidizing or reducing gases and therefore this article focuses on surface reduction processes and the interaction of oxygen with these surfaces. The systems that are discussed are: (i) the oxygen vacancy formation on the surface of the ion conductor CeO(2)(111); (ii) interaction of oxygen with TiO(2) (both adsorption processes and the incorporation of oxygen into the TiO(2)(110) lattice are discussed); (iii) the varying surface composition of SnO(2)(101) and its consequence for the adsorption of water; and (iv) Cu modified ZnO(0001)-Zn surfaces and its interaction with oxygen. These examples are chosen to give a comprehensive overview of surface science studies of different kinds of gas sensing materials and to illustrate the potential that surface science studies have to give fundamental insight into gas sensing phenomena.

  14. The development of an electrochemical technique for in situ calibrating of combustible gas detectors

    Science.gov (United States)

    Shumar, J. W.; Lantz, J. B.; Schubert, F. H.

    1976-01-01

    A program to determine the feasibility of performing in situ calibration of combustible gas detectors was successfully completed. Several possible techniques for performing the in situ calibration were proposed. The approach that showed the most promise involved the use of a miniature water vapor electrolysis cell for the generation of hydrogen within the flame arrestor of a combustible gas detector to be used for the purpose of calibrating the combustible gas detectors. A preliminary breadboard of the in situ calibration hardware was designed, fabricated and assembled. The breadboard equipment consisted of a commercially available combustible gas detector, modified to incorporate a water vapor electrolysis cell, and the instrumentation required for controlling the water vapor electrolysis and controlling and calibrating the combustible gas detector. The results showed that operation of the water vapor electrolysis at a given current density for a specific time period resulted in the attainment of a hydrogen concentration plateau within the flame arrestor of the combustible gas detector.

  15. Nitrogen oxides emissions from the MILD combustion with the conditions of recirculation gas.

    Science.gov (United States)

    Park, Min; Shim, Sung Hoon; Jeong, Sang Hyun; Oh, Kwang-Joong; Lee, Sang-Sup

    2017-04-01

    The nitrogen oxides (NOx) reduction technology by combustion modification which has economic benefits as a method of controlling NOx emitted in the combustion process, has recently been receiving a lot of attention. Especially, the moderate or intense low oxygen dilution (MILD) combustion which applied high temperature flue gas recirculation has been confirmed for its effectiveness with regard to solid fuel as well. MILD combustion is affected by the flue gas recirculation ratio and the composition of recirculation gas, so its NOx reduction efficiency is determined by them. In order to investigate the influence of factors which determine the reduction efficiency of NOx in MILD coal combustion, this study changed the flow rate and concentration of nitrogen (N2), carbon dioxide (CO2) and steam (H2O) which simulate the recirculation gas during the MILD coal combustion using our lab-scale drop tube furnace and performed the combustion experiment. As a result, its influence by the composition of recirculation gas was insignificant and it was shown that flue gas recirculation ratio influences the change of NOx concentration greatly. We investigated the influence of factors determining the nitrogen oxides (NOx) reduction efficiency in MILD coal combustion, which applied high-temperature flue gas recirculation. Using a lab-scale drop tube furnace and simulated recirculation gas, we conducted combustion testing changing the recirculation gas conditions. We found that the flue gas recirculation ratio influences the reduction of NOx emissions the most.

  16. Gas Composition Sensing Using Carbon Nanotube Arrays

    Science.gov (United States)

    Li, Jing; Meyyappan, Meyya

    2012-01-01

    This innovation is a lightweight, small sensor for inert gases that consumes a relatively small amount of power and provides measurements that are as accurate as conventional approaches. The sensing approach is based on generating an electrical discharge and measuring the specific gas breakdown voltage associated with each gas present in a sample. An array of carbon nanotubes (CNTs) in a substrate is connected to a variable-pulse voltage source. The CNT tips are spaced appropriately from the second electrode maintained at a constant voltage. A sequence of voltage pulses is applied and a pulse discharge breakdown threshold voltage is estimated for one or more gas components, from an analysis of the current-voltage characteristics. Each estimated pulse discharge breakdown threshold voltage is compared with known threshold voltages for candidate gas components to estimate whether at least one candidate gas component is present in the gas. The procedure can be repeated at higher pulse voltages to estimate a pulse discharge breakdown threshold voltage for a second component present in the gas. The CNTs in the gas sensor have a sharp (low radius of curvature) tip; they are preferably multi-wall carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs), to generate high-strength electrical fields adjacent to the tips for breakdown of the gas components with lower voltage application and generation of high current. The sensor system can provide a high-sensitivity, low-power-consumption tool that is very specific for identification of one or more gas components. The sensor can be multiplexed to measure current from multiple CNT arrays for simultaneous detection of several gas components.

  17. Single Chip Sensing of Multiple Gas Flows

    CERN Document Server

    Bruschi, P; Piotto, M

    2008-01-01

    The fabrication and experimental characterization of a thermal flow meter, capable of detecting and measuring two independent gas flows with a single chip, is described. The device is based on a 4 x 4 mm2 silicon chip, where a series of differential micro-anemometers have been integrated together with standard electronic components by means of postprocessing techniques. The innovative aspect of the sensor is the use of a plastic adapter, thermally bonded to the chip, to convey the gas flow only to the areas where the sensors are located. The use of this inexpensive packaging procedure to include different sensing structures in distinct flow channels is demonstrated.

  18. Direct Numerical Simulation of biomass pyrolysis and combustion with gas phase reactions

    NARCIS (Netherlands)

    Aswasthi, A.; Kuerten, J.G.M.; Geurts, B.J.

    2016-01-01

    We present Direct Numerical Simulation of biomass pyrolysis and combustion in a turbulent channel flow. The model includes simplified models for biomass pyrolysis and char combustion along with a model for particle tracking. The gas phase is modelled as a mixture of reacting gas species. The gas-pa

  19. A novel gas-droplet numerical method for spray combustion

    Science.gov (United States)

    Chen, C. P.; Shang, H. M.; Jiang, Y.

    1991-01-01

    This paper presents a non-iterative numerical technique for computing time-dependent gas-droplet flows. The method is a fully-interacting combination of Eulerian fluid and Lagrangian particle calculation. The interaction calculations between the two phases are formulated on a pressure-velocity coupling procedure based on the operator-splitting technique. This procedure eliminates the global iterations required in the conventional particle-source-in-cell (PSIC) procedure. Turbulent dispersion calculations are treated by a stochastic procedure. Numerical calculations and comparisons with available experimental data, as well as efficiency assessments are given for some sprays typical of spray combustion applications.

  20. Industrial gas turbine combustion system for biogas applications

    Energy Technology Data Exchange (ETDEWEB)

    Kelsall, G.J.; Cannon, M.F.; Witton, J.J. [Alstom Power Technology Centre, Whetstone (United Kingdom)

    2004-07-01

    This paper concentrates on work carried out within a UK DTI supported project, to assess and choose the most appropriate gas turbine combustor technology for commercial biomass and coal gasification applications. A particular issue was the control of CO and NOx emissions over the full gas turbine operating envelope. The project has involved the design of a combustor to burn low calorific value (LCV) fuel gases based on a dry low emissions combustion system. Tests of this combustor, together with benchmark testing of an existing diffusion-flame LCV combustor used successfully in the field, have been completed. These tests were carried out at full engine pressure using a 4 MJ/kg synthetic fuel gas mixture representative of an air blown gasification fuel gas. Further testing of the diffusion flame combustor was carried out using a 10 MJ/kg synthetic fuel gas mixture, representative of oxygen blown gasification fuel gas. This was introduced specifically to assess the suitability of the combustor for underground coal gasification, as applicable to the proposed UK scenario. 8 refs., 7 figs., 3 tabs.

  1. Capacitive Structures for Gas and Biological Sensing

    KAUST Repository

    Sapsanis, Christos

    2015-04-01

    The semiconductor industry was benefited by the advances in technology in the last decades. This fact has an impact on the sensors field, where the simple transducer was evolved into smart miniaturized multi-functional microsystems. However, commercially available gas and biological sensors are mostly bulky, expensive, and power-hungry, which act as obstacles to mass use. The aim of this work is gas and biological sensing using capacitive structures. Capacitive sensors were selected due to its design simplicity, low fabrication cost, and no DC power consumption. In the first part, the dominant structure among interdigitated electrodes (IDEs), fractal curves (Peano and Hilbert) and Archimedean spiral was investigated from capacitance density perspective. The investigation consists of geometrical formula calculations, COMSOL Multiphysics simulations and cleanroom fabrication of the capacitors on a silicon substrate. Moreover, low-cost fabrication on flexible plastic PET substrate was conducted outside cleanroom with rapid prototyping using a maskless laser etching. The second part contains the humidity, Volatile Organic compounds (VOCs) and Ammonia sensing of polymers, Polyimide and Nafion, and metal-organic framework (MOF), Cu(bdc)2.xH2O using IDEs and tested in an automated gas setup for experiment control and data extraction. The last part includes the biological sensing of C - reactive protein (CRP) quantification, which is considered as a biomarker of being prone to cardiac diseases and Bovine serum albumin (BSA) protein quantification, which is used as a reference for quantifying unknown proteins.

  2. Vibro-acoustical instabilities induced by combustion dynamics in gas turbine combustors

    NARCIS (Netherlands)

    Pozarlik, Artur

    2010-01-01

    The lean premixed combustion suffers from a high sensitivity to thermo-acoustic instabilities which may occur in a combustion chamber of a gas turbine. The high level of acoustic excitation is hazardous to the combustion chamber walls (liner). The situation is even worse when mutual interaction betw

  3. Gas Turbine Combustion and Ammonia Removal Technology of Gasified Fuels

    Directory of Open Access Journals (Sweden)

    Takeharu Hasegawa

    2010-03-01

    Full Text Available From the viewpoints of securing a stable supply of energy and protecting our global environment in the future, the integrated gasification combined cycle (IGCC power generation of various gasifying methods has been introduced in the world. Gasified fuels are chiefly characterized by the gasifying agents and the synthetic gas cleanup methods and can be divided into four types. The calorific value of the gasified fuel varies according to the gasifying agents and feedstocks of various resources, and ammonia originating from nitrogenous compounds in the feedstocks depends on the synthetic gas clean-up methods. In particular, air-blown gasified fuels provide low calorific fuel of 4 MJ/m3 and it is necessary to stabilize combustion. In contrast, the flame temperature of oxygen-blown gasified fuel of medium calorie between approximately 9–13 MJ/m3 is much higher, so control of thermal-NOx emissions is necessary. Moreover, to improve the thermal efficiency of IGCC, hot/dry type synthetic gas clean-up is needed. However, ammonia in the fuel is not removed and is supplied into the gas turbine where fuel-NOx is formed in the combustor. For these reasons, suitable combustion technology for each gasified fuel is important. This paper outlines combustion technologies and combustor designs of the high temperature gas turbine for various IGCCs. Additionally, this paper confirms that further decreases in fuel-NOx emissions can be achieved by removing ammonia from gasified fuels through the application of selective, non-catalytic denitration. From these basic considerations, the performance of specifically designed combustors for each IGCC proved the proposed methods to be sufficiently effective. The combustors were able to achieve strong results, decreasing thermal-NOx emissions to 10 ppm (corrected at 16% oxygen or less, and fuel-NOx emissions by 60% or more, under conditions where ammonia concentration per fuel heating value in unit volume was 2.4 × 102 ppm

  4. Hot-gas filtration for pressurized fluidized-bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Chang, R.; Kuby, W.

    1984-03-01

    This topical report discusses the status of the work, conducted under EPRI contract 1336-4, on the evaluation and development of ceramic filter hot gas cleanup technology for pressurized fluidized bed combustion. This topical report represents the status of the work through September 1983. The goal of the effort is to achieve 6000 h of operation on a 13-filter durability test rig. The work includes two parallel tasks. The first is construction of a durability test facility, operation of the facility with an initial candidate filter media installed, and assessment of results. The second task includes a literature survey to identify state-of-the-art ceramic fibers suitable for high-temperature gas filtration applications and filter testing in a single-filter test facility to assess the performance of promising new filter media. The best candidate will be chosen for further evaluation in the durability facility.

  5. Soot filter for the exhaust gas of internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Abthoff, J.; Schuster, H.D.; Langer, H.J.

    1980-06-19

    In the previously known soot filters, the exhaust gas flows through the cylindrical filter radially from the outside to the inside. The exhaust gas touches a relatively large area of the filter housing and therefore loses a large part of the thermal energy required for post-combustion. According to the invention, these disadvantages are avoided in the new filter, where the filter material forms hollow spaces at the internal wall of the filter, which take the exhaust gas after it has flowed through the filter and carry it in an axial direction of the filter housing to the exhaust. Due to this design of the filter and the saving in heat, the areas on which the exhaust gas impinges can be kept appreciably smaller and better use can be made of the heat in the exhaust gas. The ceramic filter material can consist of an outer layer of loose ceramic fibres and an inner woven ceramic fibre mat. In order to increase the effectiveness of the filter, the soot filter can be used as a fine filter after a coarse filter.

  6. Numerical simulation for explosion wave propagation of combustible mixture gas

    Institute of Scientific and Technical Information of China (English)

    WANG Cheng; NING Jian-guo; MA Tian-bao

    2008-01-01

    A two-dimensional multi-material code was indigenously developed to investigate the effects of duct boundary conditions and ignition positions on the propagation law of explosion wave for hydrogen and methane-based combustible mixture gas. In the code, Young's technique was employed to track the interface between the explosion products and air, and combustible function model was adopted to simulate ignition process. The code was employed to study explosion flow field inside and outside the duct and to obtain peak pressures in different boundary conditions and ignition positions. Numerical results suggest that during the propagation in a duct, for point initiation, the curvature of spherical wave front gradually decreases and evolves into plane wave. Due to the multiple reflections on the duct wall, multi-peak values appear on pressure-time curve, and peak pressure strongly relies on the duct boundary conditions and ignition position. When explosive wave reaches the exit of the duct, explosion products expand outward and forms shock wave in air. Multiple rarefaction waves also occur and propagate upstream along the duct to decrease the pressure in the duct. The results are in agreement with one-dimensional isentropic gas flow theory of the explosion products, and indicate that the ignition model and multi-material interface treatment method are feasible.

  7. THE COMBUSTION ACTION VERIFICATION AND ESTIMATE OF COMBUSTION EFFICIENCY IN AVIATION GAS#TURBINE ENGINE COMBUSTION CHAMBERS

    OpenAIRE

    2011-01-01

    Verification results of combustion action simulating and estimate of calculation combustion efficiency that was given by simulating were shown. Mathematical model and its assumption are described. Execution calculations method was shown. Results of simulating are shown; their comparative analyses with results of experiment were executed. Accuracy of combustion action mathematical modeling by combustion efficiency in model with oneand two-stage reactions of combustion was estimated. The infere...

  8. High-temperature CO / HC gas sensors to optimize firewood combustion in low-power fireplaces

    Directory of Open Access Journals (Sweden)

    B. Ojha

    2017-06-01

    Full Text Available In order to optimize firewood combustion in low-power firewood-fuelled fireplaces, a novel combustion airstream control concept based on the signals of in situ sensors for combustion temperature, residual oxygen concentration and residual un-combusted or partly combusted pyrolysis gas components (CO and HC has been introduced. A comparison of firing experiments with hand-driven and automated airstream-controlled furnaces of the same type showed that the average CO emissions in the high-temperature phase of the batch combustion can be reduced by about 80 % with the new control concept. Further, the performance of different types of high-temperature CO / HC sensors (mixed-potential and metal oxide types, with reference to simultaneous exhaust gas analysis by a high-temperature FTIR analysis system, was investigated over 20 batch firing experiments (∼ 80 h. The distinctive sensing behaviour with respect to the characteristically varying flue gas composition over a batch firing process is discussed. The calculation of the Pearson correlation coefficients reveals that mixed-potential sensor signals correlate more with CO and CH4; however, different metal oxide sensitive layers correlate with different gas species: 1 % Pt / SnO2 designates the presence of CO and 2 % ZnO / SnO2 designates the presence of hydrocarbons. In the case of a TGS823 sensor element, there was no specific correlation with one of the flue gas components observed. The stability of the sensor signals was evaluated through repeated exposure to mixtures of CO, N2 and synthetic air after certain numbers of firing experiments and exhibited diverse long-term signal instabilities.

  9. A combustion model for studying the effects of ideal gas properties on jet noise

    Science.gov (United States)

    Jacobs, Jerin; Tinney, Charles

    2016-11-01

    A theoretical combustion model is developed to simulate the influence of ideal gas effects on various aeroacoustic parameters over a range of equivalence ratios. The motivation is to narrow the gap between laboratory and full-scale jet noise testing. The combustion model is used to model propane combustion in air and kerosene combustion in air. Gas properties from the combustion model are compared to real lab data acquired at the National Center for Physical Acoustics at the University of Mississippi as well as outputs from NASA's Chemical Equilibrium Analysis code. Different jet properties are then studied over a range of equivalence ratios and pressure ratios for propane combustion in air, kerosene combustion in air and heated air. The findings reveal negligible differences between the three constituents where the density and sound speed ratios are concerned. Albeit, the area ratio required for perfectly expanded flow is shown to be more sensitive to gas properties, relative to changes in the temperature ratio.

  10. Densitometry and temperature measurement of combustion gas by X-ray Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, Hiroshi, E-mail: sakuraih@gunma-u.ac.jp [Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Kawahara, Nobuyuki [Okayama University, Tsushima-Naka 3, Okayama 700-8530 (Japan); Itou, Masayoshi [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Tomita, Eiji [Okayama University, Tsushima-Naka 3, Okayama 700-8530 (Japan); Suzuki, Kosuke [Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Sakurai, Yoshiharu [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2016-02-17

    Measurement of combustion gas by high-energy X-ray Compton scattering is reported. Measurement of combustion gas by high-energy X-ray Compton scattering is reported. The intensity of Compton-scattered X-rays has shown a position dependence across the flame of the combustion gas, allowing us to estimate the temperature distribution of the combustion flame. The energy spectra of Compton-scattered X-rays have revealed a significant difference across the combustion reaction zone, which enables us to detect the combustion reaction. These results demonstrate that high-energy X-ray Compton scattering can be employed as an in situ technique to probe inside a combustion reaction.

  11. Numerical Simulation of NOx Formation in Coal Combustion with Inlet Natural Gas Burning

    Institute of Scientific and Technical Information of China (English)

    张宇; 周力行; 魏小林; 盛宏至

    2005-01-01

    A full two-fluid model of reacting gas-particle flows and coal combustion is used to simulate coal combustion with and without inlet natural gas added in the inlet. The simulation results for the case without natural gas burning is in fair agreement with the experimental results reported in references. The simulation results of different natural gas adding positions indicate that the natural gas burning can form lean oxygen combustion enviroment at the combustor inlet region and the NOx concentration is reduced. The same result can be obtained from chemical equilibrium analysis.

  12. 10 CFR 50.44 - Combustible gas control for nuclear power reactors.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Combustible gas control for nuclear power reactors. 50.44... FACILITIES Standards for Licenses, Certifications, and Regulatory Approvals § 50.44 Combustible gas control for nuclear power reactors. (a) Definitions—(1) Inerted atmosphere means a containment atmosphere...

  13. 40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being retained...

  14. Development of colorless distributed combustion for gas turbine application

    Science.gov (United States)

    Arghode, Vaibhav Kumar

    Colorless Distributed Combustion (CDC) is investigated for gas turbine engine application due to its benefit for ultra-low pollutant emission, improved pattern factor, low noise emission, stable combustion and low pressure drop, alleviation of combustion instabilities and increased life of turbine blades with less air cooling requirements. The CDC is characterized by discrete and direct injection of fuel and air at high velocity and the reaction zone is stabilized due to controlled aerodynamics inside the combustor and wider (radially) shear layer mixing. Mixing between the injected air and product gases to form hot and diluted oxidant is required followed by rapid mixing with the fuel. This results in distributed reaction zone instead of a concentrated flame front as observed in conventional diffusion flames and hence, to avoid hot spot regions and provide reduced NOx and CO emissions. The focus of this dissertation is to develop and demonstrate CDC for application to stationary gas turbine combustors which generally operate at thermal intensity of 15MW/m3-atm. However, higher thermal intensity is desirable to reduce hardware costs due to smaller weight and volume of the combustors. Design of high thermal intensity CDC combustor requires careful control of critical parameters, such as, gas recirculation, fuel/oxidizer mixing and residence time characteristics via careful selection of different air and fuel injection configurations to achieve desirable combustion characteristics. This dissertation examines sequential development of low emission colorless distributed combustor operating from thermal intensity of 5MW/m3-atm up to 198MW/m3-atm. Initially, various fuel and air injection configurations were investigated at a low thermal intensity of 5MW/m 3-atm. Further investigations were performed for a simpler combustor having single air and fuel injection ports for medium thermal intensity range of 28-57MW/m3-atm. Among the flow configurations investigated, reverse

  15. Validation of DWPF Melter Off-Gas Combustion Model

    Energy Technology Data Exchange (ETDEWEB)

    Choi, A.S.

    2000-08-23

    The empirical melter off-gas combustion model currently used in the DWPF safety basis calculations is valid at melter vapor space temperatures above 570 degrees C, as measured in the thermowell. This lower temperature bound coincides with that of the off-gas data used as the basis of the model. In this study, the applicability of the empirical model in a wider temperature range was assessed using the off-gas data collected during two small-scale research melter runs. The first data set came from the Small Cylindrical Melter-2 run in 1985 with the sludge feed coupled with the precipitate hydrolysis product. The second data set came from the 774-A melter run in 1996 with the sludge-only feed prepared with the modified acid addition strategy during the feed pretreatment step. The results of the assessment showed that the data from these two melter runs agreed well with the existing model, and further provided the basis for extending the lower temperature bound of the model to the measured melter vapor space temperature of 445 degrees C.

  16. MCO combustible gas management leak test acceptance criteria

    Energy Technology Data Exchange (ETDEWEB)

    SHERRELL, D.L.

    1999-05-11

    Existing leak test acceptance criteria for mechanically sealed and weld sealed multi-canister overpacks (MCO) were evaluated to ensure that MCOs can be handled and stored in stagnant air without compromising the Spent Nuclear Fuel Project's overall strategy to prevent accumulation of combustible gas mixtures within MCO's or within their surroundings. The document concludes that the integrated leak test acceptance criteria for mechanically sealed and weld sealed MCOs (1 x 10{sup -5} std cc/sec and 1 x 10{sup -7} std cc/sec, respectively) are adequate to meet all current and foreseeable needs of the project, including capability to demonstrate compliance with the NFPA 60 Paragraph 3-3 requirement to maintain hydrogen concentrations [within the air atmosphere CSB tubes] t or below 1 vol% (i.e., at or below 25% of the LFL).

  17. Development and test of combustion chamber for Stirling engine heated by natural gas

    Science.gov (United States)

    Li, Tie; Song, Xiange; Gui, Xiaohong; Tang, Dawei; Li, Zhigang; Cao, Wenyu

    2014-04-01

    The combustion chamber is an important component for the Stirling engine heated by natural gas. In the paper, we develop a combustion chamber for the Stirling engine which aims to generate 3˜5 kWe electric power. The combustion chamber includes three main components: combustion module, heat exchange cavity and thermal head. Its feature is that the structure can divide "combustion" process and "heat transfer" process into two apparent individual steps and make them happen one by one. Since natural gas can mix with air fully before burning, the combustion process can be easily completed without the second wind. The flame can avoid contacting the thermal head of Stirling engine, and the temperature fields can be easily controlled. The designed combustion chamber is manufactured and its performance is tested by an experiment which includes two steps. The experimental result of the first step proves that the mixture of air and natural gas can be easily ignited and the flame burns stably. In the second step of experiment, the combustion heat flux can reach 20 kW, and the energy utilization efficiency of thermal head has exceeded 0.5. These test results show that the thermal performance of combustion chamber has reached the design goal. The designed combustion chamber can be applied to a real Stirling engine heated by natural gas which is to generate 3˜5 kWe electric power.

  18. Sensitivity of natural gas HCCI combustion to fuel and operating parameters using detailed kinetic modeling

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S; Dibble, R; Flowers, D; Smith, J R; Westbrook, C K

    1999-07-19

    This paper uses the HCT (Hydrodynamics, Chemistry and Transport) chemical kinetics code to analyze natural gas HCCI combustion in an engine. The HCT code has been modified to better represent the conditions existing inside an engine, including a wall heat transfer correlation. Combustion control and low power output per displacement remain as two of the biggest challenges to obtaining satisfactory performance out of an HCCI engine, and these are addressed in this paper. The paper considers the effect of natural gas composition on HCCI combustion, and then explores three control strategies for HCCI engines: DME (dimethyl ether) addition, intake heating and hot EGR addition. The results show that HCCI combustion is sensitive to natural gas composition, and an active control may be required to compensate for possible changes in composition. The three control strategies being considered have a significant effect in changing the combustion parameters for the engine, and should be able to control HCCI combustion.

  19. Effect of Gas Mixture Composition on the Parameters of an Internal Combustion Engine

    Directory of Open Access Journals (Sweden)

    Andrej Chríbik

    2012-01-01

    Full Text Available This paper deals with the use of the internal combustion piston engine, which is a drive unit for micro-cogeneration units. The introduction is a brief statement of the nature of gas mixture compositions that are useful for the purposes of combustion engines, together with the basic physical and chemical properties relevant to the burning of this gas mixture. Specifically, we will discuss low-energy gases (syngases and mixtures of natural gas with hydrogen. The second section describes the conversion of the Lombardini LGW 702 combustion engine that is necessary for these types of combustion gases. Before the experimental measurements, a simulation in the Lotus Engine simulation program was carried out to make a preliminary assessment of the impact on the performance of an internal combustion engine. The last section of the paper presents the experimental results of partial measurements of the performance and emission parameters of an internal combustion engine powered by alternative fuels.

  20. Advanced Materials for Mercury 50 Gas Turbine Combustion System

    Energy Technology Data Exchange (ETDEWEB)

    Price, Jeffrey

    2008-09-30

    Solar Turbines Incorporated (Solar), under cooperative agreement number DE-FC26-0CH11049, has conducted development activities to improve the durability of the Mercury 50 combustion system to 30,000 hours life and reduced life cycle costs. This project is part of Advanced Materials in the Advanced Industrial Gas Turbines program in DOE's Office of Distributed Energy. The targeted development engine was the Mercury{trademark} 50 gas turbine, which was developed by Solar under the DOE Advanced Turbine Systems program (DOE contract number DE-FC21-95MC31173). As a generator set, the Mercury 50 is used for distributed power and combined heat and power generation and is designed to achieve 38.5% electrical efficiency, reduced cost of electricity, and single digit emissions. The original program goal was 20,000 hours life, however, this goal was increased to be consistent with Solar's standard 30,000 hour time before overhaul for production engines. Through changes to the combustor design to incorporate effusion cooling in the Generation 3 Mercury 50 engine, which resulted in a drop in the combustor wall temperature, the current standard thermal barrier coated liner was predicted to have 18,000 hours life. With the addition of the advanced materials technology being evaluated under this program, the combustor life is predicted to be over 30,000 hours. The ultimate goal of the program was to demonstrate a fully integrated Mercury 50 combustion system, modified with advanced materials technologies, at a host site for a minimum of 4,000 hours. Solar was the Prime Contractor on the program team, which includes participation of other gas turbine manufacturers, various advanced material and coating suppliers, nationally recognized test laboratories, and multiple industrial end-user field demonstration sites. The program focused on a dual path development route to define an optimum mix of technologies for the Mercury 50 and future gas turbine products. For liner and

  1. New regulations, combustion, environment: responses for natural gas; Nouvelles reglementations, combustion, environnement: les reponses pour le gaz naturel

    Energy Technology Data Exchange (ETDEWEB)

    Le Peltier-Marc, A. [Gaz de France (GDF), 75 - Paris (France). Direction Commerciale

    1997-12-31

    The impacts of the new French regulations concerning low- to medium-power combustion equipment with regards to their energy sources, energy efficiency and pollution control, on natural gas fired boilers, are discussed: lower pollutant emission limits are set for SO{sub 2}, NO{sub x} and ashes. The decree gives new regulations concerning plant location, combustion control systems, plant monitoring and maintenance, and air pollution control measures such as chimney stack height and emission limits. The French national gas utility promotes environmental high performance boilers

  2. Resonance Based Micromechanical Cantilever for Gas Sensing

    Directory of Open Access Journals (Sweden)

    Subhashini. S

    2013-04-01

    Full Text Available Our world is facing some drastic changes in the climatic conditions due to the heating effect caused by various greenhouse gases. The most harmful gas among them is Carbon dioxide and is increasing at anuncontrolled rate.This paper aims in finding out the quantity of the major polluting gas carbon dioxide. The gravimetric sensor works by adsorbing the CO2 molecules on ZnO sensing layer, which alters the overall mass of the sensor. The mechanical structure is a cantilever, having its own resonant frequency. To selectively adsorbCO2 molecules from the mixture of gaseous molecules, ZnO at a specific temperature is used. As the gas molecules are adsorbed the mass increases and hence there is a change in resonant frequency. This change in frequency gives the measure of the quantity of CO2 molecules present in that environment. The major expected advantage of this technique would be the repeatability of the sensor that is used. This Quantitative analysis of CO2 would be helpful for mankind by alerting them about the environment in which they work,by proper conditioning and networking

  3. Dynamic properties of combustion instability in a lean premixed gas-turbine combustor.

    Science.gov (United States)

    Gotoda, Hiroshi; Nikimoto, Hiroyuki; Miyano, Takaya; Tachibana, Shigeru

    2011-03-01

    We experimentally investigate the dynamic behavior of the combustion instability in a lean premixed gas-turbine combustor from the viewpoint of nonlinear dynamics. A nonlinear time series analysis in combination with a surrogate data method clearly reveals that as the equivalence ratio increases, the dynamic behavior of the combustion instability undergoes a significant transition from stochastic fluctuation to periodic oscillation through low-dimensional chaotic oscillation. We also show that a nonlinear forecasting method is useful for predicting the short-term dynamic behavior of the combustion instability in a lean premixed gas-turbine combustor, which has not been addressed in the fields of combustion science and physics.

  4. The Development of a Rebust Accelerometer-Based Start of Combustion Sensing System

    Energy Technology Data Exchange (ETDEWEB)

    Jim Huang; David Mumford

    2009-01-31

    The development of modern combustion systems increasingly relies on detailed knowledge of the combustion event. As the limits of combustion are approached, tight control of combustion leads to improved emissions and higher efficiencies, while retaining and even improving engine reliability and durability. While developing a novel HCCI (Homogeneous Charge Compression Ignition) technology for large natural gas engines, Westport found that there was no reliable cost-effective technology to monitor the combustion event. As a result, Westport began working on developing a solution based on commercially available knock sensors. While initially developed around HCCI, Westport has identified that numerous other forms of combustion (high EGR systems, Homogeneous Charge Direct Injection, etc) will require combustion sensors. This requirement is also reflected in the development of other technologies in this field. However, the potential low system cost and the lack of intrusion into the cylinder head area are significant benefits for the Westport approach. Previous work by Westport has proven the method on two different large compression ignition gas engines. The objective of the current work is to improve the robustness of this technology; particularly, to identify and reduce the sensor-to-sensor and engine-to-engine variations.

  5. Methods for Gas Sensing with Single-Walled Carbon Nanotubes

    Science.gov (United States)

    Kaul, Anupama B. (Inventor)

    2013-01-01

    Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

  6. Advanced Materials for Mercury 50 Gas Turbine Combustion System

    Energy Technology Data Exchange (ETDEWEB)

    Price, Jeffrey

    2008-09-30

    Solar Turbines Incorporated (Solar), under cooperative agreement number DE-FC26-0CH11049, has conducted development activities to improve the durability of the Mercury 50 combustion system to 30,000 hours life and reduced life cycle costs. This project is part of Advanced Materials in the Advanced Industrial Gas Turbines program in DOE's Office of Distributed Energy. The targeted development engine was the Mercury{trademark} 50 gas turbine, which was developed by Solar under the DOE Advanced Turbine Systems program (DOE contract number DE-FC21-95MC31173). As a generator set, the Mercury 50 is used for distributed power and combined heat and power generation and is designed to achieve 38.5% electrical efficiency, reduced cost of electricity, and single digit emissions. The original program goal was 20,000 hours life, however, this goal was increased to be consistent with Solar's standard 30,000 hour time before overhaul for production engines. Through changes to the combustor design to incorporate effusion cooling in the Generation 3 Mercury 50 engine, which resulted in a drop in the combustor wall temperature, the current standard thermal barrier coated liner was predicted to have 18,000 hours life. With the addition of the advanced materials technology being evaluated under this program, the combustor life is predicted to be over 30,000 hours. The ultimate goal of the program was to demonstrate a fully integrated Mercury 50 combustion system, modified with advanced materials technologies, at a host site for a minimum of 4,000 hours. Solar was the Prime Contractor on the program team, which includes participation of other gas turbine manufacturers, various advanced material and coating suppliers, nationally recognized test laboratories, and multiple industrial end-user field demonstration sites. The program focused on a dual path development route to define an optimum mix of technologies for the Mercury 50 and future gas turbine products. For liner and

  7. Nanoscale Metal Oxide Semiconductors for Gas Sensing

    Science.gov (United States)

    Hunter, Gary W.; Evans, Laura; Xu, Jennifer C.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.

    2011-01-01

    A report describes the fabrication and testing of nanoscale metal oxide semiconductors (MOSs) for gas and chemical sensing. This document examines the relationship between processing approaches and resulting sensor behavior. This is a core question related to a range of applications of nanotechnology and a number of different synthesis methods are discussed: thermal evaporation- condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed, providing a processing overview to developers of nanotechnology- based systems. The results of a significant amount of testing and comparison are also described. A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. The TECsynthesized single-crystal nanowires offer uniform crystal surfaces, resistance to sintering, and their synthesis may be done apart from the substrate. The TECproduced nanowire response is very low, even at the operating temperature of 200 C. In contrast, the electrospun polycrystalline nanofiber response is high, suggesting that junction potentials are superior to a continuous surface depletion layer as a transduction mechanism for chemisorption. Using a catalyst deposited upon the surface in the form of nanoparticles yields dramatic gains in sensitivity for both nanostructured, one-dimensional forms. For the nanowire materials, the response magnitude and response rate uniformly increase with increasing operating temperature. Such changes are interpreted in terms of accelerated surface diffusional processes, yielding greater access to chemisorbed oxygen species and faster dissociative chemisorption, respectively. Regardless of operating temperature, sensitivity of the nanofibers is a factor of 10 to 100 greater than that of nanowires with the same catalyst for the same test condition. In summary, nanostructure appears critical to governing the reactivity, as measured by electrical

  8. Evaluation of reduced chemical kinetic mechanisms used for modeling mild combustion for natural gas

    Directory of Open Access Journals (Sweden)

    Hamdi Mohamed

    2009-01-01

    Full Text Available A numerical and parametric study was performed to evaluate the potential of reduced chemistry mechanisms to model natural gas chemistry including NOx chemistry under mild combustion mode. Two reduced mechanisms, 5-step and 9-step, were tested against the GRI-Mech3.0 by comparing key species, such as NOx, CO2 and CO, and gas temperature predictions in idealized reactors codes under mild combustion conditions. It is thus concluded that the 9-step mechanism appears to be a promising reduced mechanism that can be used in multi-dimensional codes for modeling mild combustion of natural gas.

  9. Turbulence, combustion, efficiency and emission measurements on a supercharged natural gas SI engine

    Energy Technology Data Exchange (ETDEWEB)

    Einewall, P.; Olsson, Magnus

    1996-08-01

    LDV was used to measure turbulence in six different combustion chambers for a natural gas operated TD102 Volvo truck engine. The efficiency and emissions were measured during supercharged lean operation. The combustion chambers were altered by using pistons with different crown geometries. Some of the load cases require supercharged operation of the engine. The cooling of the cylinder-head was therefore improved. Turbulence, combustion rate, emissions and efficiency was measured for four different piston design. 8 refs, figs

  10. Advanced Combustion Systems for Next Generation Gas Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Joel Haynes; Jonathan Janssen; Craig Russell; Marcus Huffman

    2006-01-01

    Next generation turbine power plants will require high efficiency gas turbines with higher pressure ratios and turbine inlet temperatures than currently available. These increases in gas turbine cycle conditions will tend to increase NOx emissions. As the desire for higher efficiency drives pressure ratios and turbine inlet temperatures ever higher, gas turbines equipped with both lean premixed combustors and selective catalytic reduction after treatment eventually will be unable to meet the new emission goals of sub-3 ppm NOx. New gas turbine combustors are needed with lower emissions than the current state-of-the-art lean premixed combustors. In this program an advanced combustion system for the next generation of gas turbines is being developed with the goal of reducing combustor NOx emissions by 50% below the state-of-the-art. Dry Low NOx (DLN) technology is the current leader in NOx emission technology, guaranteeing 9 ppm NOx emissions for heavy duty F class gas turbines. This development program is directed at exploring advanced concepts which hold promise for meeting the low emissions targets. The trapped vortex combustor is an advanced concept in combustor design. It has been studied widely for aircraft engine applications because it has demonstrated the ability to maintain a stable flame over a wide range of fuel flow rates. Additionally, it has shown significantly lower NOx emission than a typical aircraft engine combustor and with low CO at the same time. The rapid CO burnout and low NOx production of this combustor made it a strong candidate for investigation. Incremental improvements to the DLN technology have not brought the dramatic improvements that are targeted in this program. A revolutionary combustor design is being explored because it captures many of the critical features needed to significantly reduce emissions. Experimental measurements of the combustor performance at atmospheric conditions were completed in the first phase of the program

  11. Towards Control-Oriented Modeling of Natural Gas-Diesel RCCI Combustion

    NARCIS (Netherlands)

    Bekdemir, C.; Baert, R.; Willems, F.; Somers, B.

    2015-01-01

    For natural gas (NG)-diesel RCCI, a multi-zonal, detailed chemistry modeling approach is presented. This dual fuel combustion process requires further understanding of the ignition and combustion processes to maximize thermal efficiency and minimize (partially) unburned fuel emissions. The introduct

  12. Prediction of limit cycle pressure oscillations in gas turbine combustion systems using the flame describing function

    NARCIS (Netherlands)

    Krediet, H.J.

    2012-01-01

    Thermo-acoustic analysis is crucial for a successful development of new gas turbine combustion systems. In this context, it becomes more and more necessary to predict the limit cycle pressure amplitude of thermo-acoustic combustion instabilities to figure out if they are within the critical design l

  13. Prediction of limit cycle pressure oscillations in gas turbine combustion systems using the flame describing function

    NARCIS (Netherlands)

    Krediet, H.J.

    2012-01-01

    Thermo-acoustic analysis is crucial for a successful development of new gas turbine combustion systems. In this context, it becomes more and more necessary to predict the limit cycle pressure amplitude of thermo-acoustic combustion instabilities to figure out if they are within the critical design l

  14. Towards Control-Oriented Modeling of Natural Gas-Diesel RCCI Combustion

    NARCIS (Netherlands)

    Bekdemir, C.; Baert, R.; Willems, F.; Somers, B.

    2015-01-01

    For natural gas (NG)-diesel RCCI, a multi-zonal, detailed chemistry modeling approach is presented. This dual fuel combustion process requires further understanding of the ignition and combustion processes to maximize thermal efficiency and minimize (partially) unburned fuel emissions. The

  15. Development and Application of Gas Sensing Technologies to Enable Boiler Balancing

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Prabir

    2008-12-31

    Identifying gas species and their quantification is important for optimization of many industrial applications involving high temperatures, including combustion processes. CISM (Center for Industrial Sensors and Measurements) at the Ohio State University has developed CO, O{sub 2}, NO{sub x}, and CO{sub 2} sensors based on TiO{sub 2} semiconducting oxides, zirconia and lithium phosphate based electrochemical sensors and sensor arrays for high-temperature emission control. The underlying theme in our sensor development has been the use of materials science and chemistry to promote high-temperature performance with selectivity. A review article presenting key results of our studies on CO, NO{sub x}, CO{sub 2} and O{sub 2} sensors is described in: Akbar, Sheikh A.; Dutta, Prabir K. Development and Application of Gas Sensing Technologies for Combustion Processes, PowerPlant Chemistry, 9(1) 2006, 28-33.

  16. Graphene Hybrid Materials in Gas Sensing Applications †

    Science.gov (United States)

    Latif, Usman; Dickert, Franz L.

    2015-01-01

    Graphene, a two dimensional structure of carbon atoms, has been widely used as a material for gas sensing applications because of its large surface area, excellent conductivity, and ease of functionalization. This article reviews the most recent advances in graphene hybrid materials developed for gas sensing applications. In this review, synthetic approaches to fabricate graphene sensors, the nano structures of hybrid materials, and their sensing mechanism are presented. Future perspectives of this rapidly growing field are also discussed. PMID:26690156

  17. Combustion

    CERN Document Server

    Glassman, Irvin

    1987-01-01

    Combustion, Second Edition focuses on the underlying principles of combustion and covers topics ranging from chemical thermodynamics and flame temperatures to chemical kinetics, detonation, ignition, and oxidation characteristics of fuels. Diffusion flames, flame phenomena in premixed combustible gases, and combustion of nonvolatile fuels are also discussed. This book consists of nine chapters and begins by introducing the reader to heats of reaction and formation, free energy and the equilibrium constants, and flame temperature calculations. The next chapter explores the rates of reactio

  18. Condition Based Monitoring of Gas Turbine Combustion Components

    Energy Technology Data Exchange (ETDEWEB)

    Ulerich, Nancy; Kidane, Getnet; Spiegelberg, Christine; Tevs, Nikolai

    2012-09-30

    The objective of this program is to develop sensors that allow condition based monitoring of critical combustion parts of gas turbines. Siemens teamed with innovative, small companies that were developing sensor concepts that could monitor wearing and cracking of hot turbine parts. A magnetic crack monitoring sensor concept developed by JENTEK Sensors, Inc. was evaluated in laboratory tests. Designs for engine application were evaluated. The inability to develop a robust lead wire to transmit the signal long distances resulted in a discontinuation of this concept. An optical wear sensor concept proposed by K Sciences GP, LLC was tested in proof-of concept testing. The sensor concept depended, however, on optical fiber tips wearing with the loaded part. The fiber tip wear resulted in too much optical input variability; the sensor could not provide adequate stability for measurement. Siemens developed an alternative optical wear sensor approach that used a commercial PHILTEC, Inc. optical gap sensor with an optical spacer to remove fibers from the wearing surface. The gap sensor measured the length of the wearing spacer to follow loaded part wear. This optical wear sensor was developed to a Technology Readiness Level (TRL) of 5. It was validated in lab tests and installed on a floating transition seal in an F-Class gas turbine. Laboratory tests indicate that the concept can measure wear on loaded parts at temperatures up to 800{degrees}C with uncertainty of < 0.3 mm. Testing in an F-Class engine installation showed that the optical spacer wore with the wearing part. The electro-optics box located outside the engine enclosure survived the engine enclosure environment. The fiber optic cable and the optical spacer, however, both degraded after about 100 operating hours, impacting the signal analysis.

  19. Combustion Chamber Deposits and PAH Formation in SI Engines Fueled by Producer Gas from Biomass Gasification

    DEFF Research Database (Denmark)

    Ahrenfeldt, Jesper; Henriksen, Ulrik Birk; Schramm, Jesper

    2003-01-01

    Investigations were made concerning the formation of combustion chamber deposits (CCD) in SI gas engines fueled by producer gas. The main objective was to determine and characterise CCD and PAH formation caused by the presence of the light tar compounds phenol and guaiacol in producer gas from an...

  20. Numerical prediction of combustion induced vibro-acoustical instabilities in a gas turbine combustor

    NARCIS (Netherlands)

    Pozarlik, Artur; Kok, Jim

    2009-01-01

    Introduction of lean premixed combustion to gas turbine technology reduced the emission of harmful exhaust gas species, but due to the high sensitivity of lean flames to acoustic perturbations, the average life time of gas turbine engines was decreased significantly. Very dangerous to the integrity

  1. Investigation of combustion and characterization of solid fuels by means of the gas-potentiometric method

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, H.; Trippler, S.; Rau, H. [Otto-von-Guericke University, Magdeburg (Germany). Chemical Inst.

    1998-12-31

    Based on experiences of many years in using solid electrolyte oxygen sensors in gas and oil flames the Gas-Potentiometric Combustion Analysis (GPCA) was developed as a new in-situ method for investigation of the complex processes of solid fuel combustion. It consists of fuel combustion in a fluidized bed reactor and the simultaneous measurement of oxygen consumption due to combustion by placing a gas-potentiometric oxygen sensor immediately in the combustion zone, i.e. the fluidizing bed. For each solid fuel, including relevant waste materials and biofuels, a characteristic oxygen concentration-time curve as a `finger print` is obtained reflecting combustion behaviour. On the basis of the burn-out curves several fuel specific parameters are derivable, e.g. the burn-out time of the fuel sample. By using a specially developed oxygen balance model the effective reaction rate constant and a value for the relative reactivity for comparison of various fuels is obtained. Finally, the overall activation energy for macrokinetics of the whole combustion process can be estimated. The combustion behaviour of a wide range of solid materials (several fuels, waste, biomass) was studied. The surface structure of all materials was studied by using the gas adsorption method (N{sub 2}). The GPCA proved to be a suitable in-situ measuring technique for investigation of solid fuel combustion and a useful method for fuel characterization. A concept for the construction of a `Gas-Potentiometric Combustion Analyzer` as a new device for cheap and fast fuel characterization was developed. 24 refs., 15 figs., 6 tabs.

  2. Characterization of complexities in combustion instability in a lean premixed gas-turbine model combustor.

    Science.gov (United States)

    Gotoda, Hiroshi; Amano, Masahito; Miyano, Takaya; Ikawa, Takuya; Maki, Koshiro; Tachibana, Shigeru

    2012-12-01

    We characterize complexities in combustion instability in a lean premixed gas-turbine model combustor by nonlinear time series analysis to evaluate permutation entropy, fractal dimensions, and short-term predictability. The dynamic behavior in combustion instability near lean blowout exhibits a self-affine structure and is ascribed to fractional Brownian motion. It undergoes chaos by the onset of combustion oscillations with slow amplitude modulation. Our results indicate that nonlinear time series analysis is capable of characterizing complexities in combustion instability close to lean blowout.

  3. Advanced combustion technologies for gas turbine power plants

    Energy Technology Data Exchange (ETDEWEB)

    Vandsburger, U.; Desu, S.B. [Virginia Tech, Blacksburg, VA (United States); Roe, L.A.

    1995-10-01

    During the second half of fiscal year 1995 progress was made in all three funded subject areas of the project as well as in a new area. Work in the area of mixing and combustion management through flow actuation was transferred into an enclosed facility. Jet mixing in a ducted co-flow was examined. The same jets were also subjected to a strong acoustic field established in the duct. Excitation of the jet with static spatial modes was shown to be effective even in the presence of co-flow and the acoustic field. Only when a wall is placed at the jet exit plane did the acoustic field dominate the jet dispersion (as expected due to reflective boundary conditions and the jet shear layer receptivity). This case is, however, not the most relevant to gas turbine combustors since it precludes co-flow. In the area of combustor testing, the design, fabrication, and assembly of a modular combustor test rig for project has been completed at the University of Arkansas. In the area of high temperature piezoceramic actuator materials development, Sr{sub 2}(Nb{sub x}Ta{sub 1-x}){sub 2}O{sub 7} powders have been synthesized, and bulk samples and thick films sintered. These materials have a curie temperature of about 1400{degrees}C compared with 300{degrees}C for the commercially available PZT. While at room temperature the new materials show a piezoelectric constant (d{sub 33}) which is a factor of 100 lower than PZT, at high temperatures they can exhibit significant action. A new area of non-linear, neural-net based, controllers for mixing and combustion control has been added during the second contract year. This work is not funded by the contract. Significant progress was made in this area. Neural nets with up to 15 neurons in the hidden layer were trained with experimental data and also with data generated using linear stability theory. System ID was performed successfully. The network was then used to predict the behavior of jets excited at other modes not used for the training.

  4. Abnormal combustion caused by lubricating oil in high BMEP gas engines

    Energy Technology Data Exchange (ETDEWEB)

    Yasueda, Shinji [Kyushu Univ. (Japan). GDEC Gas and Diesel Engine; Takasaki, Koji; Tajima, Hiroshi [Kyushu Univ. (Japan). Lab. of Engine and Combustion (ECO)

    2013-05-15

    In recent years, abnormal combustion with high peak firing pressure has been experienced on gas engines with high brake mean effective pressures. The abnormality is detected not as pre-ignition but as knocking. Research, including visualisation tests on a single-cylinder engine, has confirmed the phenomenon to be pre-ignition caused by the auto-ignition of in-cylinder lubricant, causing cyclical variations of peak firing pressure on premix combustion gas engines. (orig.)

  5. A simplified method for determining heat of combustion of natural gas

    Science.gov (United States)

    Singh, Jag J.; Chegini, Hoshang; Mall, Gerald H.

    1987-01-01

    A simplified technique for determination of the heat of combustion of natural gas has been developed. It is a variation of the previously developed technique wherein the carrier air, in which the test sample was burnt, was oxygen enriched to adjust the mole fraction of oxygen in the combustion product gases up to that in the carrier air. The new technique eliminates the need for oxygen enrichment of the experimental mixtures and natural gas samples and has been found to predict their heats of combustion to an uncertainty of the order of 1 percent.

  6. Utilization and mitigation of VAM/CMM emissions by a catalytic combustion gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, K.; Yoshino, Y.; Kashihara, H. [Kawasaki Heavy Industries Ltd., Hyougo (Japan); Kajita, S.

    2013-07-01

    A system configured with a catalytic combustion gas turbine generator unit is introduced. The system has been developed using technologies produced by Kawasaki Heavy Industries, Ltd., such as small gas turbines, recuperators and catalytic combustors, and catalytic oxidation units which use exhaust heat from gas turbines. The system combusts (oxidizes) ventilation air methane (less than 1% concentration) and low concentration coal mine methane (30% concentration or less) discharged as waste from coal mines. Thus, it cannot only reduce the consumption of high- quality fuel for power generation, but also mitigate greenhouse gas emissions.

  7. Gas-Phase Combustion Synthesis of Nonoxide Nanoparticles in Microgravity

    Science.gov (United States)

    Axelbaum, R. L.; Kumfer, B. M.; Sun, Z.; Chao, B. H.

    2001-01-01

    Gas-phase combustion synthesis is a promising process for creating nanoparticles for the growing nanostructure materials industry. The challenges that must be addressed are controlling particle size, preventing hard agglomerates, maintaining purity, and, if nonoxides are synthesized, protecting the particles from oxidation and/or hydrolysis during post-processing. Sodium-halide Flame Encapsulation (SFE) is a unique methodology for producing nonoxide nanoparticles that addresses these challenges. This flame synthesis process incorporates sodium and metal-halide chemistry, resulting in nanoparticles that are encapsulated in salt during the early stages of their growth in the flame. Salt encapsulation has been shown to allow control of particle size and morphology, while serving as an effective protective coating for preserving the purity of the core particles. Metals and compounds that have been produced using this technology include Al, W, Ti, TiB2, AlN, and composites of W-Ti and Al-AlN. Oxygen content in SFE synthesized nano- AlN has been measured by neutron activation analysis to be as low as 0.54wt.%, as compared to over 5wt.% for unprotected AlN of comparable size. The overall objective of this work is to study the SFE process and nano-encapsulation so that they can be used to produce novel and superior materials. SFE experiments in microgravity allow the study of flame and particle dynamics without the influence of buoyancy forces. Spherical sodium-halide flames are produced in microgravity by ejecting the halide from a spherical porous burner into a quiescent atmosphere of sodium vapor and argon. Experiments are performed in the 2.2 sec Drop Tower at the NASA-Glenn Research Center. Numerical models of the flame and particle dynamics were developed and are compared with the experimental results.

  8. Gas-Phase Combustion Synthesis of Aluminum Nitride Powder

    Science.gov (United States)

    Axelbaum, R. L.; Lottes, C. R.; Huertas, J. I.; Rosen, L. J.

    1996-01-01

    Due to its combined properties of high electrical resistivity and high thermal conductivity aluminum nitride (AlN) is a highly desirable material for electronics applications. Methods are being sought for synthesis of unagglomerated, nanometer-sized powders of this material, prepared in such a way that they can be consolidated into solid compacts having minimal oxygen content. A procedure for synthesizing these powders through gas-phase combustion is described. This novel approach involves reacting AlCl3, NH3, and Na vapors. Equilibrium thermodynamic calculations show that 100% yields can be obtained for these reactants with the products being AlN, NaCl, and H2. The NaCl by-product is used to coat the AlN particles in situ. The coating allows for control of AlN agglomeration and protects the powders from hydrolysis during post-flame handling. On the basis of thermodynamic and kinetic considerations, two different approaches were employed to produce the powder, in co-flow diffusion flame configurations. In the first approach, the three reactants were supplied in separate streams. In the second, the AlCl3 and NH3 were premixed with HCl and then reacted with Na vapor. X-ray diffraction (XRD) spectra of as-produced powders show only NaCl for the first case and NaCl and AlN for the second. After annealing at 775 C tinder dynamic vacuum, the salt was removed and XRD spectra of powders from both approaches show only AlN. Aluminum metal was also produced in the co-flow flame by reacting AlCl3 with Na. XRD spectra of as-produced powders show the products to be only NaCl and elemental aluminum.

  9. Advances in LES of Two-phase Combustion (II) LES of Complex Gas-Particle Flows and Coal Combustion

    Institute of Scientific and Technical Information of China (English)

    周力行; 胡璨元

    2012-01-01

    Large-eddy simulation (LES) is under its rapid development and is recognized as a possible second gen- eration of CFD methods used in engineering. Large-eddy simulation of two-phase flows and combustion is particu- larly important for engineering applications. Some investigators, including the present authors, give their review on LES of spray combustion in gas-turbine combustors and internal combustion engines. However, up to now only a few papers are related to the state-of-the-art on LES of gas-particle flows and combustion. In this paper a review of the advances in LES of complex gas-particle flows and coal combustion is presented. Different sub-grid scale (SGS) stress models and combustion models are described, some of the main results are summarized, and some research needs are discussed.

  10. Ceramic-coated components for the combustion zone of natural gas engines

    Science.gov (United States)

    Holloman, L.; Levy, A. V.

    1992-03-01

    The use of ceramic coatings on the combustion zone surfaces of large,natural gas-fueled,internal com-bustion engines is discussed. Unique handling and quality control systems are required for plasma spray-ing thin (0.25 mm,0.0010) in.coatings on up to 48.25(cm19)-in.diameter piston crowns and cylinder heads weighing up to(1200 lb).The in-service performance characteristics of two types of natural gas-fu-eled combustion engines powering natural gas compressors that had thin zirconia ceramic coatings ap-plied to their combustion zone surfaces are presented. Their performance was measured in the field be-fore and after coating. It was determined that the durability,power output,fuel consumption,exhaust emissions,and other operating characteristics all improved due to ceramic coating of the flame side sur-faces of cylinder heads,power pistons,and valves.

  11. On gas and particle radiation in pulverized fuel combustion furnaces

    DEFF Research Database (Denmark)

    Yin, Chungen

    2015-01-01

    Radiation is the principal mode of heat transfer in a combustor. This paper presents a refined weighted sum of gray gases model for computational fluid dynamics modelling of conventional air-fuel combustion, which has greater accuracy and completeness than the existing gaseous radiative property....... Although the refined gaseous radiative property model shows great advantages in gaseous fuel combustion modelling, its impacts are largely compromised in pulverized solid fuel combustion, in which particle-radiation interaction plays the dominant role in radiation heat transfer due to high particle loading....... Use of conversion-dependent particle emissivity and scattering factor will not only change the particle heating and reaction history, but also alter the radiation intensity and thus temperature profiles in the furnace. For radiation modelling in pulverized fuel combustion, the priority needs...

  12. Optical fiber gas sensing system based on FBG filtering

    Science.gov (United States)

    Wang, Shutao

    2008-10-01

    An optical fiber gas sensing system based on the law of Beer-Lambert is designed to determine the concentration of gas. This technique relies on the fact that the target gas has a unique, well-defined absorption characteristic within the infrared region of electromagnetic spectrum. The narrow-band filtering characteristic of optical fiber Bragg grating is used to produce the narrow spectrum light signal. An aspheric objective optical fiber collimator is used in the system as an optical fiber gas sensing detector to improve the sensitivity and stability. Experimental results show there is a high measuring sensitivity at 0.01%, and the measuring range goes beyond 5%.

  13. Gas sensor with multiple internal reference electrodes and sensing electrodes

    DEFF Research Database (Denmark)

    2016-01-01

    The invention relates to a potentiometric gas sensor, or potentiometric gas detection element, with multiple internal reference electrodes and multiple sensing electrodes for determining the concentrations of gas components in a gaseous mixture. The sensor for gas detection comprises: a solid...... electrolyte, at least two sensing electrodes (SEs) in solid contact with the electrolyte, and at least two internal reference electrodes (IREs) in solid contact with the electrolyte, wherein each IRE comprises a composite material, comprising a binary mixture of a metal and a metal oxide dispersed to form...

  14. Effects of inlet distortion on gas turbine combustion chamber exit temperature profiles

    Science.gov (United States)

    Maqsood, Omar Shahzada

    Damage to a nozzle guide vane or blade, caused by non-uniform temperature distributions at the combustion chamber exit, is deleterious to turbine performance and can lead to expensive and time consuming overhaul and repair. A test rig was designed and constructed for the Allison 250-C20B combustion chamber to investigate the effects of inlet air distortion on the combustion chamber's exit temperature fields. The rig made use of the engine's diffuser tubes, combustion case, combustion liner, and first stage nozzle guide vane shield. Rig operating conditions simulated engine cruise conditions, matching the quasi-non-dimensional Mach number, equivalence ratio and Sauter mean diameter. The combustion chamber was tested with an even distribution of inlet air and a 4% difference in airflow at either side. An even distribution of inlet air to the combustion chamber did not create a uniform temperature profile and varying the inlet distribution of air exacerbated the profile's non-uniformity. The design of the combustion liner promoted the formation of an oval-shaped toroidal vortex inside the chamber, creating localized hot and cool sections separated by 90° that appeared in the exhaust. Uneven inlet air distributions skewed the oval vortex, increasing the temperature of the hot section nearest the side with the most mass flow rate and decreasing the temperature of the hot section on the opposite side. Keywords: Allison 250, Combustion, Dual-Entry, Exit Temperature Profile, Gas Turbine, Pattern Factor, Reverse Flow.

  15. Numerical prediction of the chemical composition of gas products at biomass combustion and co-combustion in a domestic boiler

    Directory of Open Access Journals (Sweden)

    Radomiak Henryk

    2017-01-01

    Full Text Available In recent years the numerical modelling of biomass combustion has been successfully applied to determine the combustion mechanism and predict its products. In this study the influence of the addition of waste glycerin in biomass wood pellets on the chemical composition of exhaust gases has been investigated. The pellets have been prepared from spruceand pine wood sawdust without and with addition of waste glycerin. The waste glycerol is a undesirable by-product of biodiesel transesterification at oil manufacturing. The produced pellets were being burned in the 10 kW domestic boiler adapted to wood pellets combustion. The possibilities of pollutants generation (CO2, CO, NOx SOx and compounds containing chlorine in the exhaust gases coming from the boiler were numerically calculated using the latest version of CHEMKIN-PRO software, introduced by the American company Reaction Design. The results of the calculations correspond to the data obtained on a real object, in particular: combustion temperature, gas pressure, residence time of fuel in the burner, air flow, fuel consumption, as well as elementary composition of fuel supplied into the boiler. The proposed method of predicting the chemical composition of exhaust gases allows proper control of the combustion process and can be considered as an important step in reducing the pollutants (lower emission of NOx, SOx and CO2 neutral and thus to contribute to the improvement of the environmental quality. In addition, knowledge of the amounts of Clbased compounds produced in combustion process (under given conditions, can serve as an important hint in terms of corrosion prevention of boiler- and chimney steels.

  16. Lean-rich axial stage combustion in a can-annular gas turbine engine

    Energy Technology Data Exchange (ETDEWEB)

    Laster, Walter R.; Szedlacsek, Peter

    2016-06-14

    An apparatus and method for lean/rich combustion in a gas turbine engine (10), which includes a combustor (12), a transition (14) and a combustor extender (16) that is positioned between the combustor (12) and the transition (14) to connect the combustor (12) to the transition (14). Openings (18) are formed along an outer surface (20) of the combustor extender (16). The gas turbine (10) also includes a fuel manifold (28) to extend along the outer surface (20) of the combustor extender (16), with fuel nozzles (30) to align with the respective openings (18). A method (200) for axial stage combustion in the gas turbine engine (10) is also presented.

  17. Nongray-gas Effects in Modeling of Large-scale Oxy-fuel Combustion Processes

    DEFF Research Database (Denmark)

    Yin, Chungen

    2012-01-01

    , among which radiative heat transfer under oxy-fuel conditions is one of the fundamental issues. This paper demonstrates the nongray-gas effects in modeling of large-scale oxy-fuel combustion processes. Oxy-fuel combustion of natural gas in a large-scale utility boiler is numerically investigated...... cases. The simulation results show that the gray and non-gray calculations of the same oxy-fuel WSGGM make distinctly different predictions in the wall radiative heat transfer, incident radiative flux, radiative source, gas temperature and species profiles. In relative to the non-gray implementation...

  18. Diesel-Minimal Combustion Control of a Natural Gas-Diesel Engine

    Directory of Open Access Journals (Sweden)

    Florian Zurbriggen

    2016-01-01

    Full Text Available This paper investigates the combustion phasing control of natural gas-diesel engines. In this study, the combustion phasing is influenced by manipulating the start and the duration of the diesel injection. Instead of using both degrees of freedom to control the center of combustion only, we propose a method that simultaneously controls the combustion phasing and minimizes the amount of diesel used. Minimizing the amount of diesel while keeping the center of combustion at a constant value is formulated as an optimization problem with an equality constraint. A combination of feedback control and extremum seeking is used to solve this optimization problem online. The necessity to separate the different time scales is discussed and a structure is proposed that facilitates this separation for this specific example. The proposed method is validated by experiments on a test bench.

  19. Computational fluid dynamics analysis for a combustion chamber in an industrial gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Anzai, Thiago Koichi; Fontes, Carlo Eduardo; Ropelato, Karolline [Engineering Simulation and Scientic Software (ESSS), Florianopolis, SC (Brazil)], E-mails: anzai@esss.com.br, carlos.fontes@esss.com.br, ropelato@esss.com.br; Silva, Luis Fernando Figueira da; Alva Huapaya, Luis Enrique [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil). Dept. de Engenharia Mecanica], E-mails: luisfer@esp.puc-rio.br, luisalva@esp.puc-rio.br

    2011-04-15

    The accurate prediction of pollutant emissions from a gas turbine combustion chamber is a major concern when the equipment is subjected to long operational periods beyond its design point. Under such conditions, the flow field itself might also show big differences from the design point, leading, for instance, to undesirable hot spots or instabilities in the combustion process. A study of all possible operational conditions is economically unfeasible. Also a Direct Numerical Simulation of industrial combustors is beyond the capacity of the foreseeable computational resources, therefore models must be used to analyze such issues. This study presents the results for an industrial gas turbine combustion chamber using Computational Fluid Dynamics. The model used contained an ad-hoc parameter for which a new formulation is proposed. The influence of this new formulation is examined both in terms of the flow field structure and the combustion stabilization mechanism. (author)

  20. Device to lower NOx in a gas turbine engine combustion system

    Science.gov (United States)

    Laster, Walter R; Schilp, Reinhard; Wiebe, David J

    2015-02-24

    An emissions control system for a gas turbine engine including a flow-directing structure (24) that delivers combustion gases (22) from a burner (32) to a turbine. The emissions control system includes: a conduit (48) configured to establish fluid communication between compressed air (22) and the combustion gases within the flow-directing structure (24). The compressed air (22) is disposed at a location upstream of a combustor head-end and exhibits an intermediate static pressure less than a static pressure of the combustion gases within the combustor (14). During operation of the gas turbine engine a pressure difference between the intermediate static pressure and a static pressure of the combustion gases within the flow-directing structure (24) is effective to generate a fluid flow through the conduit (48).

  1. Knock characteristics of dual-fuel combustion in diesel engines using natural gas as primary fuel

    Indian Academy of Sciences (India)

    O M I Nwafor

    2002-06-01

    This paper investigates the combustion knock characteristics of diesel engines running on natural gas using pilot injection as means of initiating combustion. The diesel engines knock under normal operating conditions but the knock referred to in this paper is an objectionable one. In the dual-fuel combustion process we have the ignition stage followed by the combustion stage. There are three types of knock: diesel knock, spark knock and knock due to secondary ignition delay of the primary fuel (erratic knock). Several factors have been noted to feature in defining knock characteristics of dual-fuel engines that include ignition delay, pilot quantity, engine load and speed, turbulence and gas flow rate.

  2. Cyclic Combustion Variations in Dual Fuel Partially Premixed Pilot-Ignited Natural Gas Engines

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, K. K. [Mississippi State Univ., MS (United States). Dept. of Mechanical Engineering; Krishnan, S. R. [Mississippi State Univ., MS (United States). Dept. of Mechanical Engineering; Qi, Y. [Caterpillar, Inc., Peoria, IL (United States)

    2012-05-09

    Dual fuel pilot ignited natural gas engines are identified as an efficient and viable alternative to conventional diesel engines. This paper examines cyclic combustion fluctuations in conventional dual fuel and in dual fuel partially premixed low temperature combustion (LTC). Conventional dual fueling with 95% (energy basis) natural gas (NG) substitution reduces NOx emissions by almost 90%t relative to straight diesel operation; however, this is accompanied by 98% increase in HC emissions, 10 percentage points reduction in fuel conversion efficiency (FCE) and 12 percentage points increase in COVimep. Dual fuel LTC is achieved by injection of a small amount of diesel fuel (2-3 percent on an energy basis) to ignite a premixed natural gas₋air mixture to attain very low NOx emissions (less than 0.2 g/kWh). Cyclic variations in both combustion modes were analyzed by observing the cyclic fluctuations in start of combustion (SOC), peak cylinder pressures (Pmax), combustion phasing (Ca50), and the separation between the diesel injection event and Ca50 (termed "relative combustion phasing" ). For conventional dual fueling, as % NG increases, Pmax decreases, SOC and Ca50 are delayed, and cyclic variations increase. For dual fuel LTC, as diesel injection timing is advanced from 20° to 60° BTDC, the relative combustion phasing is identified as an important combustion parameter along with SoC, Pmax, and CaPmax. For both combustion modes, cyclic variations were characterized by alternating slow and fast burn cycles, especially at high %NG and advanced injection timings. Finally, heat release return maps were analyzed to demonstrate thermal management strategies as an effective tool to mitigate cyclic combustion variations, especially in dual fuel LTC.

  3. Gas cooking, kitchen ventilation, and exposure to combustion products.

    Science.gov (United States)

    Willers, S M; Brunekreef, B; Oldenwening, M; Smit, H A; Kerkhof, M; Vries, H

    2006-02-01

    We evaluated a questionnaire-based system for classifying homes into groups with distinctly different chances of accumulating combustion products from cooking appliances. The system was based on questions about type of cooking appliance, type and use of ventilation provisions, and kitchen size. Real-time measurements were made of CO, CO(2), temperature, and water vapor, and passive sampling was performed of nitrogen oxides, over a week-long period in 74 kitchens. During the measurements, inhabitants kept a diary to record appliance use time and use of ventilation provisions. The questionnaire-based and diary-based home classifications for the 'Chance of Accumulation of Combustion Products' (CACP) turned out to agree fairly well. For CO(2) as well as for CO a significant difference between the 'high' and 'low' CACP groups was found for the mean accumulation in the kitchen during cooking of the combustion generated concentrations. These facts are considered to be important experimental evidence of the CACP stratification being valid for our study population. In the homes studied, NO(2) as well as CO concentrations were found to be lower compared with previous studies in The Netherlands. Practical Implications Previous studies on indoor combustion product dispersal conducted in the early- to mid-1980s in the Netherlands showed much higher NO(2) and CO concentrations than the present study. Apparently, the removal of combustion products formed during cooking is more efficient in the (mostly newer) homes that we studied than in the homes studied in the early- to mid-1980s. More detailed knowledge of kitchen situations is needed to improve the CACP model. Future studies can achieve this by using questionnaires on the kitchen situation, diaries and real-time measurements of the combustion products under consideration.

  4. Gas turbine structural mounting arrangement between combustion gas duct annular chamber and turbine vane carrier

    Energy Technology Data Exchange (ETDEWEB)

    Wiebe, David J.; Charron, Richard C.; Morrison, Jay A.

    2016-10-18

    A gas turbine engine ducting arrangement (10), including: an annular chamber (14) configured to receive a plurality of discrete flows of combustion gases originating in respective can combustors and to deliver the discrete flows to a turbine inlet annulus, wherein the annular chamber includes an inner diameter (52) and an outer diameter (60); an outer diameter mounting arrangement (34) configured to permit relative radial movement and to prevent relative axial and circumferential movement between the outer diameter and a turbine vane carrier (20); and an inner diameter mounting arrangement (36) including a bracket (64) secured to the turbine vane carrier, wherein the bracket is configured to permit the inner diameter to move radially with the outer diameter and prevent axial deflection of the inner diameter with respect to the outer diameter.

  5. Combustion Temperature Effect of Diesel Engine Convert to Compressed Natural Gas Engine

    OpenAIRE

    Semin; Abdul R. Ismail; Rosli A. Bakar

    2009-01-01

    Effect of combustion temperature in the engine cylinder of diesel engine convert to Compressed Natural Gas (CNG) engine was presents in this study. The objective of this study was to investigate the engine cylinder combustion temperature effect of diesel engine convert to CNG engine on variation engine speed. Problem statement: The hypothesis was that the lower performance of CNG engine was caused by the effect of lower in engine cylinder temperature. Are the CNG engine is lower cylinder temp...

  6. On-line combustion monitoring on dry low NOx industrial gas turbines

    Science.gov (United States)

    Rea, S.; James, S.; Goy, C.; Colechin, M. J. F.

    2003-07-01

    To reduce the NOx emissions levels produced by industrial gas turbines most manufacturers have adopted a lean premixed approach to combustion. Such combustion systems are susceptible to combustion-driven oscillations, and much of the installed modern gas turbines continue to suffer from reduced reliability due to instability-related problems. The market conditions which now exist under the New Electricity Trading Arrangements provide a strong driver for power producers to improve the reliability and availability of their generating units. With respect to low-emission gas turbines, such improvements can best be achieved through a combination of sophisticated monitoring, combustion optimization and, where appropriate, plant modifications to reduce component failure rates. On-line combustion monitoring (OLCM) provides a vital contribution to each of these by providing the operator with increased confidence in the health of the combustion system and also by warning of the onset of combustion component deterioration which could cause significant downstream damage. The OLCM systems installed on Powergen's combined cycle gas turbine plant utilize high-temperature dynamic pressure transducers mounted close to the combustor to enable measurement of the fluctuating pressures experienced within the combustion system. Following overhaul, a reference data set is determined over a range of operating conditions. Real-time averaged frequency spectra are then compared to the reference data set to enable identification of abnormalities. Variations in the signal may occur due to changes in ambient conditions, fuel composition, operating conditions, and the onset of component damage. The systems on Powergen's plant have been used successfully to detect each of the above, examples of which are presented here.

  7. Indicated mean effective pressure oscillations in a natural gas combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Litak, Grzegorz [Dept. of Applied Mechanics, Lublin Univ. of Tech., Lublin (Poland); Dipt. di Architettura, Costruzioni e Strutture, Univ. Politecnica delle Marche, Ancona (Italy); Geca, Michal [Dept. of Applied Mechanics, Lublin Univ. of Tech., Lublin (Poland); Dept. of Thermodynamics, Fluid Mechanics and Aircraft Propulsion, Lublin Univ. of Tech., Lublin (Poland); Yao Bao-Feng; Li Guo-Xiu [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong Univ., BJ (China)

    2009-05-15

    Fluctuations in a combustion process of natural gas in the internal spark ignition engine have been investigated. We measured pressure of the cyclic combustion and expressed its cyclic oscillations in terms of indicated mean effective pressure per cycle. By applying the statistical and multifractal analysis to the corresponding time series we show the considerable changes in engine dynamics for a different equivalence ratio decreases from 0.781 to very lean conditions. (orig.)

  8. Oxidative potential of gas phase combustion emissions - An underestimated and potentially harmful component of air pollution from combustion processes

    Science.gov (United States)

    Stevanovic, S.; Vaughan, A.; Hedayat, F.; Salimi, F.; Rahman, M. M.; Zare, A.; Brown, R. A.; Brown, R. J.; Wang, H.; Zhang, Z.; Wang, X.; Bottle, S. E.; Yang, I. A.; Ristovski, Z. D.

    2017-06-01

    The oxidative potential (OP) of the gas phase is an important and neglected aspect of environmental toxicity. Whilst prolonged exposure to particulate matter (PM) associated reactive oxygen species (ROS) have been shown to lead to negative health effects, the potential for compounds in gas phase to cause similar effects is yet to be understood. In this study we describe: the significance of the gas phase OP generated through vehicle emissions; discuss the origin and evolution of species contributing to measured OP; and report on the impact of gas phase OP on human lung cells. The model aerosol for this study was exhaust emitted from a Euro III Common-rail diesel engine fuelled with different blends of diesel and biodiesel. The gas phase of these emissions was found to be potentially as hazardous as the particle phase. Fuel oxygen content was found to negatively correlate with the gas phase OP, and positively correlate with particle phase OP. This signifies a complex interaction between reactive species present in gas and particle phase. Furthermore, this interaction has an overarching effect on the OP of both particle and gas phase, and therefore the toxicity of combustion emissions.

  9. [Ecological/hygienic and toxicological evaluation of combustion products of aviation kerosene and liquefied natural gas].

    Science.gov (United States)

    Afanas'ev, R V; Berezin, G I; Raznoschikov, V V

    2006-01-01

    Products of kerosene combustion in the present-day aeroengines contain more than 200 compounds of incomplete combustion, partial oxidation, and thermal decomposition of fuel and oil. Most of these are strong toxicants for humans. Increase of temperature in the turbine engine combustion chamber led to production of very toxic nitrogen oxides. In search for the ecologically safe and less toxic alternative attention of fuel engineers was drawn to liquefied natural gas which compares well and even excels kerosene in ecological, economic and many other respects.

  10. Selective gas sensing for photonic crystal lasers

    DEFF Research Database (Denmark)

    Smith, Cameron; Christiansen, Mads Brøkner; Buss, Thomas

    2011-01-01

    We facilitate photonic crystal lasers to sense gases via an additional swelling polymer film. We describe the transduction transfer function and experimentally demonstrate an enhanced ethanol vapor sensitivity over 15 dB with low humidity crosstalk.......We facilitate photonic crystal lasers to sense gases via an additional swelling polymer film. We describe the transduction transfer function and experimentally demonstrate an enhanced ethanol vapor sensitivity over 15 dB with low humidity crosstalk....

  11. Applications of a Mid-IR Quantum Cascade Laser in Gas Sensing Research

    KAUST Repository

    Sajid, Muhammad Bilal

    2015-05-01

    Laser absorption based sensors are extensively used in a variety of gas sensing areas such as combustion, atmospheric research, human breath analysis, and high resolution infrared spectroscopy. Quantum cascade lasers have recently emerged as high resolution, high power laser sources operating in mid infrared region and can have wide tunability range. These devices provide an opportunity to access stronger fundamental and combination vibrational bands located in mid infrared region than previously accessible weaker overtone vibrational bands located in near infrared region. Spectroscopic region near 8 µm contains strong vibrational bands of methane, acetylene, hydrogen peroxide, water vapor and nitrous oxide. These molecules have important applications in a wide range of applications. This thesis presents studies pertaining to spectroscopy and combustion applications. Advancements in combustion research are imperative to achieve lower emissions and higher efficiency in practical combustion devices such as gas turbines and engines. Accurate chemical kinetic models are critical to achieve predictive models which contain several thousand reactions and hundreds of species. These models need highly reliable experimental data for validation and improvements. Shock tubes are ideal devices to obtain such information. A shock tube is a homogenous, nearly constant volume, constant pressure, adiabatic and 0-D reactor. In combination with laser absorption sensors, shock tubes can be used to measure reaction rates and species time histories of several intermediates and products formed during pyrolysis and oxidation of fuels. This work describes measurement of the decomposition rate of hydrogen peroxide which is an important intermediate species controlling reactivity of combustion system in the intermediate temperature range. Spectroscopic parameters (linestrengths, broadening coefficients and temperature dependent coefficients) are determined for various transitions of

  12. Gas sensing using air-guiding photonic bandgap fibers

    DEFF Research Database (Denmark)

    Ritar, Tuomo; Tuominen, J.; Ludvigsen, Hanne

    2004-01-01

    We demonstrate the high sensitivity of gas sensing using a novel air-guiding photonic bandgap fiber. The bandgap fiber is spliced to a standard single-mode fiber at the input end for easy coupling and filled with gas through the other end placed in a vacuum chamber. The technique is applied...

  13. Enhanced Sensing Characteristics in MEMS-based Formaldehyde Gas Sensor

    CERN Document Server

    Wang, Yu-Hsiang; Lee, Chia-Yen; Ma, R -H; Chou, Po-Cheng

    2008-01-01

    This study has successfully demonstrated a novel self-heating formaldehyde gas sensor based on a thin film of NiO sensing layer. A new fabrication process has been developed in which the Pt micro heater and electrodes are deposited directly on the substrate and the NiO thin film is deposited above on the micro heater to serve as sensing layer. Pt electrodes are formed below the sensing layer to measure the electrical conductivity changes caused by formaldehyde oxidation at the oxide surface. Furthermore, the upper sensing layer and NiO/Al2O3 co-sputtering significantly increases the sensitivity of the gas sensor, improves its detection limit capability. The microfabricated formaldehyde gas sensor presented in this study is suitable not only for industrial process monitoring, but also for the detection of formaldehyde concentrations in buildings in order to safeguard human health.

  14. Gas cooking, kitchen ventilation, and exposure to combustion products

    NARCIS (Netherlands)

    Willers, SM; Brunekreef, B; Oldenwening, M; Smit, HA; Kerkhof, M; De Vries, H

    2006-01-01

    We evaluated a questionnaire-based system for classifying homes into groups with distinctly different chances of accumulating combustion products from cooking appliances. The system was based on questions about type of cooking appliance, type and use of ventilation provisions, and kitchen size. Real

  15. CFD analysis of combustion of natural gas and syngas from biomass pyrolysis in the combustion chamber of a micro gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Fantozzi, Francesco; Laranci, Paolo; D' Alessandro, Bruno [University of Perugia (DII/UNIPG) (Italy). Dept. of Industrial Engineering], Emails: fanto@unipg.it, paolo.laranci@unipg.it, dalessandro@bio-net.it

    2009-07-01

    Micro gas turbines (MGT) can be profitably used for the production of distributed energy (DE), with the possibility to use gaseous fuels with low BTU derived from biomass or waste through the pyrolysis or gasification processes. These synthesis gases (SG) show significant differences with respect to natural gas (NG), in terms of composition, calorific value, content of hydrogen, tar and particulate matter content; such differences can be turn into problems of ignition, instability burning, difficulties in controlling the emissions and fouling. CFD analysis of the combustion process is an essential tool for identifying the main critical arising in using these gases, in order to modify existing geometries and to develop new generation of combustor for use with low BTU gases. This paper describes the activities of experimental and numerical analysis carried out to study the combustion process occurring inside an existing annular Rich-Quench-Lean (RQL) Combustion Chamber (CC) of a 80 kW MGT. In the paper some results of a CFD study of the combustion process performed with an original developed chemical models are reported in terms of temperature and velocity distributions inside the CC and in terms of compositions of turbine inlet gas and of its thermodynamic parameters (mass flow, temperature, pressure). An evaluation of pollutant emissions of CO, CO{sub 2} and NOx and a comparison with the available experimental data relating to the case of combustion of NG is also provided in the paper. Moreover, the carried out investigation concerns the case of operation with a SG fuel derived from biomass in an Integrated Pyrolysis Regenerated Plant (IPRP). (author)

  16. Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review

    OpenAIRE

    Jin-Huai Liu; Ling-Tao Kong; Shao-Bo Liu; Fan-Li Meng; Jin-Yun Liu; Zhen Jin; Yu-Feng Sun

    2012-01-01

    Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size. However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties. Lots of metal oxide nanostructures have b...

  17. Exhaust Gas Recirculation in Gas Turbines for Reduction of CO2 Emissions; Combustion Testing with Focus on Stability and Emissions

    Directory of Open Access Journals (Sweden)

    Johan E. Hustad

    2005-12-01

    Full Text Available Exhaust gas recirculation can be applied with the intention of reducing CO2 emissions. When a fraction of the exhaust gas is injected in the entry of a gas turbine, the amount of CO2 in the exhaust gas not being recirculated will be higher and less complicated to capture. However, with this change in combustion air composition, especially the reduced concentration of oxygen, the combustion process will be affected. The lower oxygen concentration decreases the stability and the increased amount of CO2, H2O and N2 will decrease the combustion temperature and thus, the NOx emissions. Testing has been performed on a 65 kW gas turbine combustor, to investigate the effect of adding N2, CO2 and O2 in the combustion process, with focus on stability and emissions of NOx. Results show that adding N2 and CO2 decreases the NOx emissions, whereas O2 addition increases the NOx emissions. The tests have been performed both in a diffusion flame (pilot burner and a premixed flame (main burner, and for additives being injected with the fuel or with the air stream. Addition into the fuel stream is proven to affect the NOx emissions the most. The stability limits of the flames are indicated with respect to mass-based additive-to-fuel ratios.

  18. Fuel Flexible Combustion Systems for High-Efficiency Utilization of Opportunity Fuels in Gas Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesan, Krishna

    2011-11-30

    The purpose of this program was to develop low-emissions, efficient fuel-flexible combustion technology which enables operation of a given gas turbine on a wider range of opportunity fuels that lie outside of current natural gas-centered fuel specifications. The program encompasses a selection of important, representative fuels of opportunity for gas turbines with widely varying fundamental properties of combustion. The research program covers conceptual and detailed combustor design, fabrication, and testing of retrofitable and/or novel fuel-flexible gas turbine combustor hardware, specifically advanced fuel nozzle technology, at full-scale gas turbine combustor conditions. This project was performed over the period of October 2008 through September 2011 under Cooperative Agreement DE-FC26-08NT05868 for the U.S. Department of Energy/National Energy Technology Laboratory (USDOE/NETL) entitled "Fuel Flexible Combustion Systems for High-Efficiency Utilization of Opportunity Fuels in Gas Turbines". The overall objective of this program was met with great success. GE was able to successfully demonstrate the operability of two fuel-flexible combustion nozzles over a wide range of opportunity fuels at heavy-duty gas turbine conditions while meeting emissions goals. The GE MS6000B ("6B") gas turbine engine was chosen as the target platform for new fuel-flexible premixer development. Comprehensive conceptual design and analysis of new fuel-flexible premixing nozzles were undertaken. Gas turbine cycle models and detailed flow network models of the combustor provide the premixer conditions (temperature, pressure, pressure drops, velocities, and air flow splits) and illustrate the impact of widely varying fuel flow rates on the combustor. Detailed chemical kinetic mechanisms were employed to compare some fundamental combustion characteristics of the target fuels, including flame speeds and lean blow-out behavior. Perfectly premixed combustion experiments were conducted to

  19. Near-Zero Emissions Oxy-Combustion Flue Gas Purification

    Energy Technology Data Exchange (ETDEWEB)

    Minish Shah; Nich Degenstein; Monica Zanfir; Rahul Solunke; Ravi Kumar; Jennifer Bugayong; Ken Burgers

    2012-06-30

    The objectives of this project were to carry out an experimental program to enable development and design of near zero emissions (NZE) CO{sub 2} processing unit (CPU) for oxy-combustion plants burning high and low sulfur coals and to perform commercial viability assessment. The NZE CPU was proposed to produce high purity CO{sub 2} from the oxycombustion flue gas, to achieve > 95% CO{sub 2} capture rate and to achieve near zero atmospheric emissions of criteria pollutants. Two SOx/NOx removal technologies were proposed depending on the SOx levels in the flue gas. The activated carbon process was proposed for power plants burning low sulfur coal and the sulfuric acid process was proposed for power plants burning high sulfur coal. For plants burning high sulfur coal, the sulfuric acid process would convert SOx and NOx in to commercial grade sulfuric and nitric acid by-products, thus reducing operating costs associated with SOx/NOx removal. For plants burning low sulfur coal, investment in separate FGD and SCR equipment for producing high purity CO{sub 2} would not be needed. To achieve high CO{sub 2} capture rates, a hybrid process that combines cold box and VPSA (vacuum pressure swing adsorption) was proposed. In the proposed hybrid process, up to 90% of CO{sub 2} in the cold box vent stream would be recovered by CO{sub 2} VPSA and then it would be recycled and mixed with the flue gas stream upstream of the compressor. The overall recovery from the process will be > 95%. The activated carbon process was able to achieve simultaneous SOx and NOx removal in a single step. The removal efficiencies were >99.9% for SOx and >98% for NOx, thus exceeding the performance targets of >99% and >95%, respectively. The process was also found to be suitable for power plants burning both low and high sulfur coals. Sulfuric acid process did not meet the performance expectations. Although it could achieve high SOx (>99%) and NOx (>90%) removal efficiencies, it could not produce by

  20. Near-Zero Emissions Oxy-Combustion Flue Gas Purification

    Energy Technology Data Exchange (ETDEWEB)

    Minish Shah; Nich Degenstein; Monica Zanfir; Rahul Solunke; Ravi Kumar; Jennifer Bugayong; Ken Burgers

    2012-06-30

    The objectives of this project were to carry out an experimental program to enable development and design of near zero emissions (NZE) CO{sub 2} processing unit (CPU) for oxy-combustion plants burning high and low sulfur coals and to perform commercial viability assessment. The NZE CPU was proposed to produce high purity CO{sub 2} from the oxycombustion flue gas, to achieve > 95% CO{sub 2} capture rate and to achieve near zero atmospheric emissions of criteria pollutants. Two SOx/NOx removal technologies were proposed depending on the SOx levels in the flue gas. The activated carbon process was proposed for power plants burning low sulfur coal and the sulfuric acid process was proposed for power plants burning high sulfur coal. For plants burning high sulfur coal, the sulfuric acid process would convert SOx and NOx in to commercial grade sulfuric and nitric acid by-products, thus reducing operating costs associated with SOx/NOx removal. For plants burning low sulfur coal, investment in separate FGD and SCR equipment for producing high purity CO{sub 2} would not be needed. To achieve high CO{sub 2} capture rates, a hybrid process that combines cold box and VPSA (vacuum pressure swing adsorption) was proposed. In the proposed hybrid process, up to 90% of CO{sub 2} in the cold box vent stream would be recovered by CO{sub 2} VPSA and then it would be recycled and mixed with the flue gas stream upstream of the compressor. The overall recovery from the process will be > 95%. The activated carbon process was able to achieve simultaneous SOx and NOx removal in a single step. The removal efficiencies were >99.9% for SOx and >98% for NOx, thus exceeding the performance targets of >99% and >95%, respectively. The process was also found to be suitable for power plants burning both low and high sulfur coals. Sulfuric acid process did not meet the performance expectations. Although it could achieve high SOx (>99%) and NOx (>90%) removal efficiencies, it could not produce by

  1. Computational fluid dynamics (CFD) analysis of an industrial gas turbine combustion chamber

    Energy Technology Data Exchange (ETDEWEB)

    Anzai, Thiago Koichi; Fontes, Carlo Eduardo; Ropelato, Karolline [Engineering Simulation and Scientic Software Ltda. (ESSS), Rio de Janeiro, RJ (Brazil)], E-mails: anzai, carlos.fontes, ropelato@esss.com.br; Silva, Luis Fernando Figueira da; Huapaya, Luis Enrique Alva [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil). Dept. of Mechanical Engineering], E-mail: luisfer.luisalva@esp.puc-rio.br

    2010-07-01

    The accurate determination of pollutant emission from gas turbine combustors is a crucial problem in situations when such equipment is subject to long periods of operation away from the design point. In such operating conditions, the flow field structure may also drastically differ from the design point one, leading to the presence of undesirable hot spots or combustion instabilities, for instance. A priori experiments on all possible operation conditions is economically unfeasible, therefore, models that allow for the prediction of combustion behavior in the full operation range could be used to instruct power plant operators on the best strategies to be adopted. Since the direct numerical simulation of industrial combustors is beyond reach of the foreseeable computational resources, simplified models should be used for such purpose. This works presents the results of the application to an industrial gas turbine combustion chamber of the CFD technique to the prediction of the reactive flow field. This is the first step on the coupling of reactive CFD results with detailed chemical kinetics modeling using chemical reactor networks, toward the goal of accurately predicting pollutant emissions. The CFD model considers the detailed geometrical information of such a combustion chamber and uses actual operating conditions, calibrated via an overall gas turbine thermodynamical simulation, as boundary conditions. This model retains the basic information on combustion staging, which occurs both in diffusion and lean premixed modes. The turbulence has been modeled using the SST-CC model, which is characterized by a well established regime of accurate predictive capability. Combustion and turbulence interaction is accounted for by using the Zimont et al. model, which makes use of on empirical expression for the turbulent combustion velocity for the closure of the progress variable transport equation. A high resolution scheme is used to solve the advection terms of the

  2. Visualizations of Gas fuel Jet and Combustion Flame on Hydrogen Rotary Engine

    OpenAIRE

    田端, 道彦; 香川, 良二

    2011-01-01

    [Abstract] In this paper, it is a purpose to obtain basic information of a hydrogen jet and combustion flame characteristics of the hydrogen rotary engine. The jet characteristics of the hydrogen gas injector were measured by using the high-speed shadowgraph method. As the result, the jet penetration of the low density gas was weak. The mixing of the direction of the jet axis was disturbed for the low jet pressure. Next, the combustion flame propagation of the hydrogen rotary engine was visua...

  3. Frozen Characteristics of NO_x and Their Related Compositions in Combustion Gas

    Institute of Scientific and Technical Information of China (English)

    苏适; 蔡崧; 徐益谦

    1994-01-01

    In order to study the produce and reduce characteristics of the NOx in the process of fuel combustion and combustion gas denitrogenation, the frozen characteristics of the NOx and their related components of uniform gases at high temperature of 1400 - 2600 K in a quenching rate of 0.2×108 -0.4×108 K/s are studied. The effects of cooling rate on the results of analysis of NO and NO2 in gases sampled by sampling probe are discussed. The mathematical models and chemical kinetic models which express the relaxation process of gas compositions in nonequilibrium condition of quenching process are constructed.

  4. Reduced and Validated Kinetic Mechanisms for Hydrogen-CO-sir Combustion in Gas Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Yiguang Ju; Frederick Dryer

    2009-02-07

    Rigorous experimental, theoretical, and numerical investigation of various issues relevant to the development of reduced, validated kinetic mechanisms for synthetic gas combustion in gas turbines was carried out - including the construction of new radiation models for combusting flows, improvement of flame speed measurement techniques, measurements and chemical kinetic analysis of H{sub 2}/CO/CO{sub 2}/O{sub 2}/diluent mixtures, revision of the H{sub 2}/O{sub 2} kinetic model to improve flame speed prediction capabilities, and development of a multi-time scale algorithm to improve computational efficiency in reacting flow simulations.

  5. Reducing water usage with rotary regenerative gas/gas heat exchangers in natural gas-fired power plants with post-combustion carbon capture

    OpenAIRE

    Herraiz, Laura; Hogg, Dougal; Cooper, Jim; Gibbins, Jon; Lucquiaud, Mathieu

    2015-01-01

    It is possible to greatly mitigate the increase of water usage associated with the addition of carbon capture to fossil fuel power generation. This article presents a first-of-a-kind feasibility study of a series of technology options with rotary regenerative gas/gas heat exchangers for the management of the water balance around post-combustion carbon capture process integrated with Combined Cycle Gas Turbine (CCGT) plants with and without exhaust gas recirculation (EGR). Hybrid cooling confi...

  6. Comparison of an Internal Combustion Engine Derating Operated on Producer Gas from Coal and Biomass Gasification

    Directory of Open Access Journals (Sweden)

    Muhammad Ade Andriansyah Efendi

    2016-06-01

    Full Text Available Gasification is an effective and clean way to convert coal and biomass into useful fuels and chemical feedstocks. Producer gas utilization for internal combustion engine has been studied, not only from biomass gasification but also from coal gasification. This paper compares the research that has done author using coal gasification with other research results using biomass gasification. Coal gasifier performance test conducted with capacity of 20 kg/h coal. The proximate and ultimate analysis of raw coal, ash product and producer gas was conducted and comparised. The result of analysis shows that the efficiency of the coal gasification was 61% while range of gasifier efficiency for biomass is between 50-80%. Meanwhile, the experimental results on the performance of internal combustion engines using gas producer shows that the derating for power generation using coal producer gas was 46% and biomass was 20-50% depend on compression ratio of engine and characteristic of producer gas

  7. Combustion of producer gas from gasification of south Sumatera lignite coal using CFD simulation

    Directory of Open Access Journals (Sweden)

    Vidian Fajri

    2017-01-01

    Full Text Available The production of gasses from lignite coal gasification is one of alternative fuel for the boiler or gas turbine. The prediction of temperature distribution inside the burner is important for the application and optimization of the producer gas. This research aims to provide the information about the influence of excess air on the temperature distribution and combustion product in the non-premixed burner. The process was carried out using producer gas from lignite coal gasification of BA 59 was produced by the updraft gasifier which is located on Energy Conversion Laboratory Mechanical Engineering Department Universitas Sriwijaya. The excess air used in the combustion process were respectively 10%, 30% and 50%. CFD Simulations was performed in this work using two-dimensional model of the burner. The result of the simulation showed an increase of excess air, a reduction in the gas burner temperature and the composition of gas (carbon dioxide, nitric oxide and water vapor.

  8. Effect of Outside Combustion Air on Gas Furnace Efficiency.

    Science.gov (United States)

    1981-10-15

    air. A furnace "model" produced from the actual data was interfaced with a computer simulation program called " TRNSYS " to test the effect of outdoor...combustion air on annual fuel consumption- This " TRNSYS " simulation program was developed by the University of Wisconsin at Madison and uses actual...66 APPENDIX D - Description of TRNSYS Program for Seasonal Efficiency .............. 72 3 LIST OF ILLUSTRATIONS Figure 1 - Efficiency

  9. Advanced coal-fueled gas turbine systems: Subscale combustion testing. Topical report, Task 3.1

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-01

    This is the final report on the Subscale Combustor Testing performed at Textron Defense Systems` (TDS) Haverhill Combustion Laboratories for the Advanced Coal-Fueled Gas Turbine System Program of the Westinghouse Electric Corp. This program was initiated by the Department of Energy in 1986 as an R&D effort to establish the technology base for the commercial application of direct coal-fired gas turbines. The combustion system under consideration incorporates a modular staged, rich-lean-quench, Toroidal Vortex Slogging Combustor (TVC) concept. Fuel-rich conditions in the first stage inhibit NO{sub x} formation from fuel-bound nitrogen; molten coal ash and sulfated sorbent are removed, tapped and quenched from the combustion gases by inertial separation in the second stage. Final oxidation of the fuel-rich gases, and dilution to achieve the desired turbine inlet conditions are accomplished in the third stage, which is maintained sufficiently lean so that here, too, NO{sub x} formation is inhibited. The primary objective of this work was to verify the feasibility of a direct coal-fueled combustion system for combustion turbine applications. This has been accomplished by the design, fabrication, testing and operation of a subscale development-type coal-fired combustor. Because this was a complete departure from present-day turbine combustors and fuels, it was considered necessary to make a thorough evaluation of this design, and its operation in subscale, before applying it in commercial combustion turbine power systems.

  10. Advanced coal-fueled gas turbine systems: Subscale combustion testing. Topical report, Task 3.1

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-01

    This is the final report on the Subscale Combustor Testing performed at Textron Defense Systems` (TDS) Haverhill Combustion Laboratories for the Advanced Coal-Fueled Gas Turbine System Program of the Westinghouse Electric Corp. This program was initiated by the Department of Energy in 1986 as an R&D effort to establish the technology base for the commercial application of direct coal-fired gas turbines. The combustion system under consideration incorporates a modular staged, rich-lean-quench, Toroidal Vortex Slogging Combustor (TVC) concept. Fuel-rich conditions in the first stage inhibit NO{sub x} formation from fuel-bound nitrogen; molten coal ash and sulfated sorbent are removed, tapped and quenched from the combustion gases by inertial separation in the second stage. Final oxidation of the fuel-rich gases, and dilution to achieve the desired turbine inlet conditions are accomplished in the third stage, which is maintained sufficiently lean so that here, too, NO{sub x} formation is inhibited. The primary objective of this work was to verify the feasibility of a direct coal-fueled combustion system for combustion turbine applications. This has been accomplished by the design, fabrication, testing and operation of a subscale development-type coal-fired combustor. Because this was a complete departure from present-day turbine combustors and fuels, it was considered necessary to make a thorough evaluation of this design, and its operation in subscale, before applying it in commercial combustion turbine power systems.

  11. Autoignition and Combustion of Natural Gas in a 4 Stroke HCCI Engine

    Science.gov (United States)

    Jun, Daesu; Ishii, Kazuaki; Iida, Norimasa

    Homogeneous charge compression ignition (HCCI) is regarded as the next generation combustion regime in terms of high thermal efficiency and low emissions. It is difficult to control autoignition timing and combustion duration because they are controlled primarily by the chemical kinetics of fuel-air mixture. In this study, it was investigated the characteristics of autoignition and combustion of natural gas in a 4 stroke HCCI engine. And also, to clarify the influence of n-butane on autoignition and combustion of natural gas, it was changed the blend ratio of n-butane from 0mol% to 10mol% in methane/n-butane/air mixtures. Autoignition strongly depends on in-cylinder gas temperature. Autoignition of natural gas occurs when in-cylinder gas temperature reaches in a range of 1000±100K under this experimental condition. To realize high thermal efficiency and low CO emissions, it is necessary to prepare operation conditions that maximum cycle temperature is over 1500K. Autoignition temperature is 25K lower by increasing n-butane blend ratio of 10%. As the blend ratio of n-butane increases, the maximum cycle temperature increases, and THC, CO emissions reduce.

  12. Gas sensing with surface acoustic wave devices

    Science.gov (United States)

    Martin, S. J.; Schweizer, K. S.; Ricco, A. J.; Zipperian, T. E.

    1985-03-01

    The use of a ZnO-on-Si surface acoustic wave (SAW) resonator as a gas sensor is discussed. In particular, the sensitivity of the device to organic vapors is examined. The planar nature of the SAW device, in which the acoustic energy is confined to within roughly one acoustic wavelength of the surface, makes the device extremely sensitive to surface perturbations. This characteristic has been exploited in the construction of SAW gas sensors in which the surface wave propagation characteristics are altered by species adsorbed from the ambient gas. The porous nature of the sputtered ZnO film, in conjunction with the microbalance capability of the SAW device, gives the sensor the ability to distinguish molecules on the basis of both size and mass.

  13. The impact of air-fuel mixture composition on SI engine performance during natural gas and producer gas combustion

    Science.gov (United States)

    Przybyła, G.; Postrzednik, S.; Żmudka, Z.

    2016-09-01

    The paper summarizers results of experimental tests of SI engine fuelled with gaseous fuels such as, natural gas and three mixtures of producer gas substitute that simulated real producer gas composition. The engine was operated under full open throttle and charged with different air-fuel mixture composition (changed value of air excess ratio). The spark timing was adjusted to obtain maximum brake torque (MBT) for each fuel and air-fuel mixture. This paper reports engine indicated performance based on in-cylinder, cycle resolved pressure measurements. The engine performance utilizing producer gas in terms of indicated efficiency is increased by about 2 percentage points when compared to fuelling with natural gas. The engine power de-rating when producer gas is utilized instead the natural gas, varies from 24% to 28,6% under stoichiometric combustion conditions. For lean burn (λ=1.5) the difference are lower and varies from 22% to 24.5%.

  14. The Influence of Hydrogen Gas on the Measures of Efficiency of Diesel Internal Combustion Engine

    Directory of Open Access Journals (Sweden)

    Jurgis Latakas

    2014-12-01

    Full Text Available In this research paper energy and ecological parameters of diesel engine which works under addition of hydrogen (10, 20, 30 l/ min are presented. A survey of research literature has shown that addition of hydrogen gases improve diesel combustion; increase indicated pressure; decrease concentration of carbon dioxide (CO2, hydrocarbons (HC, particles; decrease fuel consumptions. Results of the experiment revealed that hydrogen gas additive decreased pressure in cylinder in kinetic combustion phase. Concentration of CO2 and nitrous oxides (NOx decreased not significantly, HC – increased. Concentration of particles in engine exhaust gases significantly decreased. In case when hydrogen gas as additive was supplied, the fuel consumptions decreased a little. Using AVL BOOST software combustion process analysis was made. It was determined that in order to optimize engine work process under hydrogen additive usage, it is necessary to adjust diesel injection angle.

  15. Gas chromatograph-combustion system for 14C-accelerator mass spectrometry.

    Science.gov (United States)

    McIntyre, Cameron P; Sylva, Sean P; Roberts, Mark L

    2009-08-01

    A gas chromatograph-combustion (GC-C) system is described for the introduction of samples as CO(2) gas into a (14)C accelerator mass spectrometry (AMS) system with a microwave-plasma gas ion source. Samples are injected into a gas chromatograph fitted with a megabore capillary column that uses H(2) as the carrier gas. The gas stream from the outlet of the column is mixed with O(2) and Ar gas and passed through a combustion furnace where the H(2) carrier gas and separated components are quantitatively oxidized to CO(2) and H(2)O. Water vapor is removed using a heated nafion dryer. The Ar carries the CO(2) to the ion source. The system is able to separate and oxidize up to 10 microg of compound and transfer the products from 7.6 mL/min of H(2) carrier gas into 0.2-1.0 mL/min of Ar carrier gas. Chromatographic performance and isotopic fidelity satisfy the requirements of the (14)C-AMS system for natural abundance measurements. The system is a significant technical advance for GC-AMS and may be capable of providing an increase in sensitivity for other analytical systems such as an isotope-ratio-monitoring GC/MS.

  16. Asymptotic Analysis in a Gas-Solid Combustion Model with Pattern Formation

    Institute of Scientific and Technical Information of China (English)

    Claude-Michel BRAUNER; Lina HU; Luca LORENZI

    2013-01-01

    The authors consider a free interface problem which stems from a gas-solid model in combustion with pattern formation.A third-order,fully nonlinear,self-consistent equation for the flame front is derived.Asymptotic methods reveal that the interface approaches a solution to the Kuramoto-Sivashinsky equation.Numerical results which illustrate the dynamics are presented.

  17. Pyrogasification of blended animal manures to produce combustable gas and biochar

    Science.gov (United States)

    The objective of this study is to evaluate the efficiency of a skid-mounted pyrogasificaiton system for producing combustible gas from from animal manures: chicken litter, swine solids, and swine solids blended with rye grass. The skid-mounted pyrolysis system by the US Innovation Group, Inc. (USIG,...

  18. The N.A.C.A. Combustion Chamber Gas-sampling Valve and Some Preliminary Test Results

    Science.gov (United States)

    Spanogle, J A; Buckley, E C

    1933-01-01

    A gas sampling valve of the inertia-operated type was designed for procuring samples of the gases in the combustion chamber of internal combustion engines at identical points in successive cycles so that the analysis of the gas samples thus procured may aid in the study of the process of combustion. The operation of the valve is described. The valve was used to investigate the CO2 content of gases taken from the quiescent combustion chamber of a high speed compression-ignition engine when operating with two different multiple-orifice fuel injection nozzles. An analysis of the gas samples thus obtained shows that the state of quiescence in the combustion chamber is maintained during the combustion of the fuel.

  19. Direct Numerical Simulation of biomass pyrolysis and combustion with gas phase reactions

    Science.gov (United States)

    Awasthi, A.; Kuerten, J. G. M.; Geurts, B. J.

    2016-09-01

    We present Direct Numerical Simulation of biomass pyrolysis and combustion in a turbulent channel flow. The model includes simplified models for biomass pyrolysis and char combustion along with a model for particle tracking. The gas phase is modelled as a mixture of reacting gas species. The gas-particle interactions for mass, momentum, and energy exchange are included by two-way coupling terms. The effect of two-way coupling on the conversion time of biomass particles is found noticeable for particle volume fractions > 10-5. We also observe that at constant volume fraction the effect of two-way coupling increases as the particle size is reduced, due to the higher total heat exchange area in case of smaller particles. The inclusion of gas phase homogeneous reactions in the DNS model decreases the biomass pyrolysis time due to higher gas temperatures. In contrast, including gas phase reactions increases the combustion time of biomass due to the lower concentration of oxygen at the particle surface.

  20. Application of neural network in the study of combustion rate of natural gas/diesel dual fuel engine.

    Science.gov (United States)

    Yan, Zhao-Da; Zhou, Chong-Guang; Su, Shi-Chuan; Liu, Zhen-Tao; Wang, Xi-Zhen

    2003-01-01

    In order to predict and improve the performance of natural gas/diesel dual fuel engine (DFE), a combustion rate model based on forward neural network was built to study the combustion process of the DFE. The effect of the operating parameters on combustion rate was also studied by means of this model. The study showed that the predicted results were good agreement with the experimental data. It was proved that the developed combustion rate model could be used to successfully predict and optimize the combustion process of dual fuel engine.

  1. Application of neural network in the study of combustion rate of natural gas/diesel dual fuel engine

    Institute of Scientific and Technical Information of China (English)

    严兆大; 周重光; 苏石川; 刘震涛; 王希珍

    2003-01-01

    In order to predict and improve the performance of natural gas/diesel dual fuel engine (DFE), a combustion rate model based on forward neural network was built to study the combustion process of the DFE. The effect of the operating parameters on combustion rate was also studied by means of this model. The study showed that the predicted results were good agreement with the experimental data. It was proved that the developed combustion rate model could be used to successfully predict and optimize the combustion process of dual fuel engine.

  2. Receptors useful for gas phase chemical sensing

    Energy Technology Data Exchange (ETDEWEB)

    Jaworski, Justyn W; Lee, Seung-Wuk; Majumdar, Arunava; Raorane, Digvijay A

    2015-02-17

    The invention provides for a receptor, capable of binding to a target molecule, linked to a hygroscopic polymer or hydrogel; and the use of this receptor in a device for detecting the target molecule in a gaseous and/or liquid phase. The invention also provides for a method for detecting the presence of a target molecule in the gas phase using the device. In particular, the receptor can be a peptide capable of binding a 2,4,6-trinitrotoluene (TNT) or 2,4,-dinitrotoluene (DNT).

  3. Gas sensing method applicable to real conditions

    Science.gov (United States)

    Szczurek, A.; Maciejewska, M.

    2013-04-01

    In this work, we tested the influence of various sampling techniques and modes of operation on the response of sensor systems under real conditions. The first system was based on diffusive sampling. The second one used a dynamic method of sampling. In the third system, a stop flow mode of operation was applied. A considerable error of target gas concentration assessment was obtained in the first two cases. The error resulted from sensor signal fluctuations encountered during their exposure either to the air at the measurement point (diffusive sampling) or to the air drawn from the measurement point (dynamic sampling). The fluctuations could be attributed to the temporal variation of physical and chemical parameters of air. The main merit of the third method consists in utilizing sensor exposure under the conditions of stopped flow for the purpose of pollutant concentration assessment. While using this method, the accuracy of target gas quantification under real conditions was comparable to the one achieved when measuring standard gases. We think that the proposed method is a valuable contribution, which addresses the increasing demand for sensor systems that perform quantitative pollution assessment in workplace air, under real conditions. This paper was presented at the Conference on Optoelectronic and Electronic Sensors held in Karpacz, Poland, on 24-27 June 2012.

  4. Flash Atomization: A New Concept to Control Combustion Instability in Water-Injected Gas Turbines

    Directory of Open Access Journals (Sweden)

    Vishwas Iyengar

    2012-01-01

    Full Text Available The objective of this work is to explore methods to reduce combustor rumble in a water-injected gas turbine. Attempts to use water injection as a means to reduce NOX emissions in gas turbines have been largely unsuccessful because of increased combustion instability levels. This pulsation causes chronic fretting, wear, and fatigue that damages combustor components. Of greater concern is that liberated fragments could cause extensive damage to the turbine section. Combustion instability can be tied to the insufficient atomization of injected water; large water droplets evaporate non-uniformly that lead to energy absorption in chaotic pulses. Added pulsation is amplified by the combustion process and acoustic resonance. Effervescent atomization, where gas bubbles are injected, is beneficial by producing finely atomized droplets; the gas bubbles burst as they exit the nozzles creating additional energy to disperse the liquid. A new concept for effervescent atomization dubbed “flash atomization” is presented where water is heated to just below its boiling point in the supply line so that some of it will flash to steam as it leaves the nozzle. An advantage of flash atomization is that available heat energy can be used rather than mechanical energy to compress injection gas for conventional effervescent atomization.

  5. Amperometric sensing in the gas-phase

    Energy Technology Data Exchange (ETDEWEB)

    Knake, Rene [University of Basel, Department of Chemistry, Spitalstrasse 51, 4004 Basel (Switzerland); Jacquinot, Patrick [University of Basel, Department of Chemistry, Spitalstrasse 51, 4004 Basel (Switzerland); Hodgson, Alexia W.E. [University of Basel, Department of Chemistry, Spitalstrasse 51, 4004 Basel (Switzerland); Hauser, Peter C. [University of Basel, Department of Chemistry, Spitalstrasse 51, 4004 Basel (Switzerland)]. E-mail: peter.hauser@unibas.ch

    2005-09-06

    The design of amperometric sensors for gaseous species presents a challenge as the gas phase has to be brought into contact with a solid electrode as well as an electrolyte phase which usually is liquid. However, many species of analytical interest are electroactive, such as SO{sub 2}, NO {sub x}, O{sub 3}, CO, formaldehyde or ethanol, and electrochemical means are always attractive in designing sensors because the electronic signal is obtained directly. Therefore, different approaches have been implemented and some types of such sensors have been available commercially for quite some time. Nevertheless, many new developments with regard to an improvement of sensitivity, selectivity and in the construction of these devices have been reported over the last few years, as well as approaches to miniaturization. In this review it is attempted to give an overview of the state of the art of this field, highlighting recent developments.

  6. Formation and Control of Sulfur Oxides in Sour Gas Oxy-Combustion: Prediction Using a Reactor Network Model

    KAUST Repository

    Bongartz, Dominik

    2015-11-19

    © 2015 American Chemical Society. Sour natural gas currently requires expensive gas cleanup before it can be used in power generation because it contains large amounts of hydrogen sulfide (H2S) and carbon dioxide (CO2) that entail a low heating value and highly corrosive combustion products. A potential alternative is to use the gas directly in a gas turbine process employing oxy-fuel combustion, which could eliminate the need for gas cleanup while also enabling the application of carbon capture and sequestration, possibly combined with enhanced oil recovery (EOR). However, the exact influence of an oxy-fuel environment on the combustion products of sour gas has not been quantified yet. In this work, we used a reactor network model for the combustor and the gas turbine together with our recently assembled and validated detailed chemical reaction mechanism for sour gas combustion to investigate the influence of some basic design parameters on the combustion products of natural gas and sour gas in CO2 or H2O diluted oxy-fuel combustion as well as in conventional air combustion. Our calculations show that oxy-fuel combustion produces up to 2 orders of magnitude less of the highly corrosive product sulfur trioxide (SO3) than air combustion, which clearly demonstrates its potential in handling sulfur containing fuels. Unlike in air combustion, in oxy-fuel combustion, SO3 is mainly formed in the flame zone of the combustor and is then consumed as the combustion products are cooled in the dilution zone of the combustor and the turbine. In oxy-fuel combustion, H2O dilution leads to a higher combustion efficiency than CO2 dilution. However, if the process is to be combined with EOR, CO2 dilution makes it easier to comply with the very low levels of oxygen (O2) required in the EOR stream. Our calculations also show that it might even be beneficial to operate slightly fuel-rich because this simultaneously decreases the O2 and SO3 concentration further. The flame zone

  7. Development of Polymethylmethacrylate Based Composite for Gas Sensing Application

    Directory of Open Access Journals (Sweden)

    S. Devikala

    2011-01-01

    Full Text Available Gas detection instruments are increasingly needed for industrial health and safety, environmental monitoring and process control. Conductive polymer composites have various industrial applications. The composite prepared by mixing carbon black with polymethylmethacrylate (PMMA has very good gas sensing applications. The gas sensors based on carbon nanotube/polymer, ceramic and metal oxide composites such as epoxy, polyimide, PMMA / Barium titanate and tin oxide have also been developed. In the present work, a new composite has been prepared by using PMMA and ammonium dihydrogen phosphate (ADP. The PMMA/Ammonium dihydrogen phosphate (PMADP composites PMADP 1 and PMADP 2 were characterized by using Powder XRD. The thick films of the composite on glass plates were prepared by using a spin coating unit at 9000 rpm. The application of the thick film as gas sensor has been studied between 0 and 2000 seconds. The results reveal that the thick film of PMADP composite can function as a very good gas sensor.

  8. Distributed Fiber Optic Gas Sensing for Harsh Environment

    Energy Technology Data Exchange (ETDEWEB)

    Juntao Wu

    2008-03-14

    This report summarizes work to develop a novel distributed fiber-optic micro-sensor that is capable of detecting common fossil fuel gases in harsh environments. During the 32-month research and development (R&D) program, GE Global Research successfully synthesized sensing materials using two techniques: sol-gel based fiber surface coating and magnetron sputtering based fiber micro-sensor integration. Palladium nanocrystalline embedded silica matrix material (nc-Pd/Silica), nanocrystalline palladium oxides (nc-PdO{sub x}) and palladium alloy (nc-PdAuN{sub 1}), and nanocrystalline tungsten (nc-WO{sub x}) sensing materials were identified to have high sensitivity and selectivity to hydrogen; while the palladium doped and un-doped nanocrystalline tin oxide (nc-PdSnO{sub 2} and nc-SnO{sub 2}) materials were verified to have high sensitivity and selectivity to carbon monoxide. The fiber micro-sensor comprises an apodized long-period grating in a single-mode fiber, and the fiber grating cladding surface was functionalized by above sensing materials with a typical thickness ranging from a few tens of nanometers to a few hundred nanometers. GE found that the morphologies of such sensing nanomaterials are either nanoparticle film or nanoporous film with a typical size distribution from 5-10 nanometers. nc-PdO{sub x} and alloy sensing materials were found to be highly sensitive to hydrogen gas within the temperature range from ambient to 150 C, while nc-Pd/Silica and nc-WO{sub x} sensing materials were found to be suitable to be operated from 150 C to 500 C for hydrogen gas detection. The palladium doped and un-doped nc-SnO{sub 2} materials also demonstrated sensitivity to carbon monoxide gas at approximately 500 C. The prototyped fiber gas sensing system developed in this R&D program is based on wavelength-division-multiplexing technology in which each fiber sensor is identified according to its transmission spectra features within the guiding mode and cladding modes. The

  9. Development of gas sensing application for formaldehyde gas detection and characterization of tin dioxide

    Science.gov (United States)

    Zaki, M.; Hashim, U.; Arshad, M. K. Md; Nasir, M.

    2017-03-01

    This paper presents the development of sensor in ultrasensitive detection of formaldehyde gas. The chemical compound, tin dioxide (SnO2) thin film is deposited onto glass insulator. Next, the resistance and voltage of the sensing layer on the interdigitated electrodes (IDE) sensor's substrate is measured. The resistivity of sensor is changed by heat the sensing layer to 150 °C, 175 °C and 200 °C. When formaldehyde gas is supplied inside the test chamber, absorption process occurred at the surface of the heated SnO2 sensing layer. The experimental results show the sensor is capable of high sensitivity sensing of formaldehyde gas at 200 °C, repeatability, and capability detection as low as 11 ppm which produced 0.8 V on electronic reader. Characterization of surface morphological, temperature effect and electrical properties are demonstrated by various measurements.

  10. Experimental and numerical investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, Jimmy; Jensen, Peter Arendt; Hvid, S.L.

    2009-01-01

    the conditions in the freeboard of it grate-fired boiler. Here, in part 2, the ability of CFD to predict volatile N oxidation to NO and N(2) is evaluated. Trace amounts of ammonia were added to the natural gas, and local measurements of NH(3) and NO in the reactor were compared to modeling predictions. Different...

  11. Release of Inorganic Elements during Wood Combustion. Release to the Gas Phase of Inorganic Elements during: Wood Combustion. Part 1: Development and Evaluation of Quantification Methods

    DEFF Research Database (Denmark)

    van Lith, Simone Cornelia; Alonso-Ramírez, Violeta; Jensen, Peter Arendt

    2006-01-01

    During wood combustion, inorganic elements such as alkali metals, sulfur, chlorine, and some heavy metals are partly released to the gas phase, which may cause problems in combustion facilities because of deposit formation and corrosion. Furthermore, it may cause harmful emissions of gases......) in this reactor, whereas methods B and C involved initial pyrolysis and combustion, respectively, of a large fuel sample (~5 kg) in a bench-scale fixed-bed reactor at 500 C. The methods were evaluated by comparing the data on the release of Cl, S, K, Na, Zn, and Pb from fiber board obtained by the three methods...

  12. Singularity of a combustion wave profile: a clue to the multi-component theory for liquid-gas filtration combustion

    CERN Document Server

    Kokubun, Max Endo

    2016-01-01

    We study a nonlinear wave for a system of balance laws in one space dimension, which describes combustion for two-phase (gas and liquid) flow in porous medium. The problem is formulated for a general $N$-component liquid for modeling the strong multi-component effects reported recently for an application to light oil recovery by air injection. Despite the immense complexity of the model, the problem allows analytic solution. The clue to this solution is a special form of a folding singularity, which occurs at an internal point of the wave profile. Analysis of this singularity provides a missing determining relation for wave parameters. This result is not only interesting for the application under consideration, but also motivates a deeper mathematical study of such singularities for general systems of balance laws.

  13. Microwave assisted combustion synthesis of nanocrystalline CoFe2O4 for LPG sensing

    Science.gov (United States)

    Chaudhari, Prashant; Acharya, S. A.; Darunkar, S. S.; Gaikwad, V. M.

    2015-08-01

    A microwave-assisted citrate precursor method has been utilized for synthesis of nanocrystalline powders of CoFe2O4. The process takes only a few minutes to obtain as-synthesized CoFe2O4. Structural properties of the synthesized material were investigated by X-ray diffraction; scanning electron microscopy, Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy. The gas sensing properties of thick film of CoFe2O4 prepared by screen printing towards Liquid Petroleum Gas (LPG) revealed that CoFe2O4 thick films are sensitive and shows maximum sensitivity at 350°C for 2500 ppm of LPG.

  14. CFD Modeling of Syngas Combustion and Emissions for Marine Gas Turbine Applications

    Directory of Open Access Journals (Sweden)

    Ammar Nader R.

    2016-09-01

    Full Text Available Strong restrictions on emissions from marine power plants will probably be adopted in the near future. One of the measures which can be considered to reduce exhaust gases emissions is the use of alternative fuels. Synthesis gases are considered competitive renewable gaseous fuels which can be used in marine gas turbines for both propulsion and electric power generation on ships. The paper analyses combustion and emission characteristics of syngas fuel in marine gas turbines. Syngas fuel is burned in a gas turbine can combustor. The gas turbine can combustor with swirl is designed to burn the fuel efficiently and reduce the emissions. The analysis is performed numerically using the computational fluid dynamics code ANSYS FLUENT. Different operating conditions are considered within the numerical runs. The obtained numerical results are compared with experimental data and satisfactory agreement is obtained. The effect of syngas fuel composition and the swirl number values on temperature contours, and exhaust gas species concentrations are presented in this paper. The results show an increase of peak flame temperature for the syngas compared to natural gas fuel combustion at the same operating conditions while the NO emission becomes lower. In addition, lower CO2 emissions and increased CO emissions at the combustor exit are obtained for the syngas, compared to the natural gas fuel.

  15. Combustion Dynamics and Control for Ultra Low Emissions in Aircraft Gas-Turbine Engines

    Science.gov (United States)

    DeLaat, John C.

    2011-01-01

    Future aircraft engines must provide ultra-low emissions and high efficiency at low cost while maintaining the reliability and operability of present day engines. The demands for increased performance and decreased emissions have resulted in advanced combustor designs that are critically dependent on efficient fuel/air mixing and lean operation. However, all combustors, but most notably lean-burning low-emissions combustors, are susceptible to combustion instabilities. These instabilities are typically caused by the interaction of the fluctuating heat release of the combustion process with naturally occurring acoustic resonances. These interactions can produce large pressure oscillations within the combustor and can reduce component life and potentially lead to premature mechanical failures. Active Combustion Control which consists of feedback-based control of the fuel-air mixing process can provide an approach to achieving acceptable combustor dynamic behavior while minimizing emissions, and thus can provide flexibility during the combustor design process. The NASA Glenn Active Combustion Control Technology activity aims to demonstrate active control in a realistic environment relevant to aircraft engines by providing experiments tied to aircraft gas turbine combustors. The intent is to allow the technology maturity of active combustion control to advance to eventual demonstration in an engine environment. Work at NASA Glenn has shown that active combustion control, utilizing advanced algorithms working through high frequency fuel actuation, can effectively suppress instabilities in a combustor which emulates the instabilities found in an aircraft gas turbine engine. Current efforts are aimed at extending these active control technologies to advanced ultra-low-emissions combustors such as those employing multi-point lean direct injection.

  16. Lean-Burn Cogeneration Biogas Engine with Unscavenged Combustion Prechamber: Comparison with Natural Gas

    Directory of Open Access Journals (Sweden)

    Roger Röthlisberger

    2002-12-01

    Full Text Available Gaseous fuels produced, for example, by waste or agricultural by-products fermentation (biogas can be burned in-situ by cogeneration systems like spark-ignition internal combustion engines. However, the more and more stringent legislation for exhaust gas emissions requires improvement of the combustion process particularly when catalytic after treatment is not reliable as in the case of sewage or landfill biogas. The system proposed in this paper is the use of an unscavenged combustion prechamber instead of direct ignition on a turbocharged 6 cylinder 150 kW gas engine. This prechamber is used for operation with a simulated biogas (40% CO2 in natural gas. The results show that, compared to natural gas operation for the same rated power output of 150 kW and the same NOx emissions, the CO emissions are reduced by 15% and the HC emissions at least by 8%. Efficiencies higher than 36% are achieved which is very promising and the lower CO emissions give a margin to consider an increase of compression ratio.

  17. Multi Canister Overpack (MCO) Combustible Gas Management Leak Test Acceptance Criteria (OCRWM)

    Energy Technology Data Exchange (ETDEWEB)

    SHERRELL, D.L.

    2000-10-10

    The purpose of this document is to support the Spent Nuclear Fuel Project's combustible gas management strategy while avoiding the need to impose any requirements for oxygen free atmospheres within storage tubes that contain multi-canister overpacks (MCO). In order to avoid inerting requirements it is necessary to establish and confirm leak test acceptance criteria for mechanically sealed and weld sealed MCOs that are adequte to ensure that, in the unlikely event the leak test results for any MCO were to approach either of those criteria, it could still be handled and stored in stagnant air without compromising the SNF Project's overall strategy to prevent accumulation of combustible gas mixtures within MCOs or within their surroundings. To support that strategy, this document: (1) establishes combustible gas management functions and minimum functional requirements for the MCO's mechanical seals and closure weld(s); (2) establishes a maximum practical value for the minimum required initial MCO inert backfill gas pressure; and (3) based on items 1 and 2, establishes and confirms leak test acceptance criteria for the MCO's mechanical seal and final closure weld(s).

  18. Synthesis, characterization and gas sensing performance of aluminosilicate azide cancrinite

    Indian Academy of Sciences (India)

    A V BORHADE; T A KSHIRSAGAR; S G WAKCHAURE; A G DHOLI

    2016-10-01

    The present investigation deals with synthesis and gas sensing performance of Na$_8$[AlSiO$_4$]$_6$(N$_3$)$_{2.4}$(H$_2$O)$_{4.6}$ cancrinite-based thick film. The product obtained was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, thermogravimetric analysis and magic-angle spin nuclear magneticresonance (MAS NMR). The crystal structure of the product was determined from X-ray powder diffraction data by applying Rietveld refinement. Refinement showed that azide cancrinite crystallize in the space group P6$_3$. Alternate arrangement of Si and Al atoms was confirmed by single intense peak of MAS NMR analysis. For the first time, this study reports the gas sensing performance of aluminosilicate azide cancrinite. The effect of annealing andoperating temperature on gas sensing characteristic of azide cancrinite thick film is investigated systematically for various gases at different operating temperatures. This sensor was observed to be highly sensitive and selective toammonia gas.

  19. Hematite nanoplates: Controllable synthesis, gas sensing, photocatalytic and magnetic properties.

    Science.gov (United States)

    Hao, Hongying; Sun, Dandan; Xu, Yanyan; Liu, Ping; Zhang, Guoying; Sun, Yaqiu; Gao, Dongzhao

    2016-01-15

    Uniform hematite (α-Fe2O3) nanoplates exposing {001} plane as basal planes have been prepared by a facile solvothermal method under the assistance of sodium acetate. The morphological evolution of the nanoplates was studied by adjusting the reaction parameters including the solvent and the amount of sodium acetate. The results indicated that both the adequate nucleation/growth rate and selective adsorption of alcohol molecules and acetate anions contribute to the formation of the plate-like morphology. In addition, the size of the nanoplates can be adjusted from ca. 180nm to 740nm by changing the reaction parameters. Three nanoplate samples with different size were selected to investigate the gas sensing performance, photocatalytic and magnetic properties. As gas sensing materials, all the α-Fe2O3 nanoplates exhibited high gas sensitivity and stability toward n-butanol. When applied as photocatalyst, the α-Fe2O3 nanoplates show high photodegradation efficiency towards RhB. Both the gas sensing performance and the photocatalytic property of the products exhibit obvious size-dependent effect. Magnetic measurements reveal that the plate-like α-Fe2O3 particles possess good room temperature magnetic properties.

  20. Effect of water blending on bioethanol HCCI combustion with forced induction and residual gas trapping

    Energy Technology Data Exchange (ETDEWEB)

    Megaritis, A. [Mechanical Engineering, School of Engineering and Design, Brunel University, West London, Uxbridge UB8 3PH (United Kingdom); Yap, D. [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Wyszynski, M.L. [Mechanical and Manufacturing Engineering, School of Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2007-12-15

    There is increased interest worldwide in renewable engine fuels as well as in new combustion technologies. Bioethanol is one of the alternative fuels that have been used successfully in spark ignition engines. A combustion technology that currently attracts a lot of interest is the homogeneous charge compression ignition (HCCI) combustion, which has shown potential for low nitrogen oxides emissions with no particulate matter formation. The authors have shown previously that applying forced induction to bioethanol HCCI with residual gas trapping results in an extended load range compared to naturally aspirated operation. However, at high boost pressures, high cylinder pressure rise rates develop. Work by other researchers has shown that direct injection of water can be used as a combustion control method. The present work explores water blending as a way that might have an effect on combustion in order to lower the maximum pressure rise rates and further improve emissions. The obtained experimental results show that in contrast to variable rate direct injection of water, fixed rate water-ethanol blending is counterproductive for the reduction of pressure rise rates at higher loads. In addition, increasing the water content in ethanol results in reduction of the effective load range and increased emissions. (author)

  1. Performance of a flameless combustion furnace using biogas and natural gas.

    Science.gov (United States)

    Colorado, A F; Herrera, B A; Amell, A A

    2010-04-01

    Flameless combustion technology has proved to be flexible regarding the utilization of conventional fuels. This flexibility is associated with the main characteristic of the combustion regime, which is the mixing of the reactants above the autoignition temperature of the fuel. Flameless combustion advantages when using conventional fuels are a proven fact. However, it is necessary to assess thermal equipments performance when utilizing bio-fuels, which usually are obtained from biomass gasification and the excreta of animals in bio-digesters. The effect of using biogas on the performance of an experimental furnace equipped with a self-regenerative Flameless burner is reported in this paper. All the results were compared to the performance of the system fueled with natural gas. Results showed that temperature field and uniformity are similar for both fuels; although biogas temperatures were slightly lower due to the larger amount of inert gases (CO(2)) in its composition that cool down the reactions. Species patterns and pollutant emissions showed similar trends and values for both fuels, and the energy balance for biogas showed a minor reduction of the efficiency of the furnace; this confirms that Flameless combustion is highly flexible to burn conventional and diluted fuels. Important modifications on the burner were not necessary to run the system using biogas. Additionally, in order to highlight the advantages of the Flameless combustion regime, some comparisons of the burner performance working in Flameless mode and working in conventional mode are presented.

  2. Experimental and simulation studies of combustion of blended fuel oil for use in industrial gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, A.; Ani, F.N. [Teknologi Malaysia Univ., Johor (Malaysia). Faculty of Mechanical Engineering; Mamat, Z.A.; Zardi, Z. [TNB Research, Selangor (Malaysia); Aziz, A. [Prai Power Station, Penang (Malaysia)

    2006-07-01

    This paper described a preliminary investigation of the combustion properties of palm olein distillate blended with diesel in a combustion chamber. The aim of the study was to examine the efficacy of the fuel for use in industrial gas turbines with an unmodified gas system. Experiments were conducted for 100 per cent diesel and blends of diesel with 20, 40, and 50 per cent palm olein distillate. Combustion firing experiments were also conducted for 100 per cent palm olein distillates. Results of the study demonstrated that nitroge oxide (NO{sub x}) emissions ranged from between 30 and 55 ppm. Computational fluid dynamics (CFD) modelling was conducted in order to compare the performance of the various blends. Results showed that flow and temperature contours for fuels with lower palm olein percentages had a more uniform combustion process due to a higher rate of fuel vaporization. It was concluded that palm olein distillate blends of more than 40 per cent are not recommended, as the soot particles of higher blends cause damage to turbine casings. 6 refs., 2 tabs., 10 figs.

  3. Pressurised combustion of biomass-derived, low calorific value, fuel gas

    Energy Technology Data Exchange (ETDEWEB)

    Andries, J.; Hoppesteyn, P.D.J.; Hein, K.R.G. [Lab. for Thermal Power Engineering, Dept. of Mechanical Engineering and Marine Technology, Delft Univ. of Technology (Netherlands)

    1996-12-31

    The Laboratory for Thermal Power Engineering of the Delft University of Technology is participating in an EU-funded, international R + D project which is designed to aid European industry in addressing issues regarding pressurised combustion of biomass-derived, low calorific flue fuel gas. The objects of the project are: To design, manufacture and test a pressurised, high temperature gas turbine combustor for biomass derived LCV fuel gas; to develop a steady-state and dynamic model describing a combustor using biomass-derived, low calorific value fuel gases; to gather reliable experimental data on the steady-state and dynamic characteristics of the combustor; to study the steady-state and dynamic plant behaviour using a plant layout wich incorporates a model of a gas turbine suitable for operation on low calorific value fuel gas. (orig)

  4. Design of a gas turbine combustion system for an ABGC plant

    Energy Technology Data Exchange (ETDEWEB)

    Kelsall, G.J.; Whinfrey, J.; Armstrong, S.J. [European Gas Turbines Limited (United Kingdom)

    1998-06-01

    Advanced coal based power generation systems such as the Air Blown Gasification Cycle (ABGC) offer the potential for high efficiency electricity generation with low environmental impact. An important component of the ABGC development programme is the design of a gas turbine combustion system to burn the coal-derived low calorific value (LCV) fuel-gas. The overall objective of this project was to provide a detailed bill of materials for the gas turbine combustion system forming part of the ABGC. The approach adopted was to minimise the required change to existing turbine components. High-confidence feasibility design concepts were provided for both the air offtake and fuel-gas manifolds to achieve acceptable air and fuel distributions. These distributions were {+-} 0.8% for the air offtake from four existing ports on the turbine casing and + 1.3% to -0.7% for the fuel distribution to the ten combustor fuel injectors. A second prototype (Prototype-2) combustor performed well during experimental testing using a purpose-built facility at European Gas Turbines (EGT`s) Whetstone site. Firing of a simulated fuel-gas achieved high performance levels. Low emission levels of CO and NO{sub x} were achieved. 9 refs., 3 figs. 6 tabs.

  5. Influence of carbonation under oxy-fuel combustion flue gas on the leachability of heavy metals in MSWI fly ash.

    Science.gov (United States)

    Ni, Peng; Xiong, Zhuo; Tian, Chong; Li, Hailong; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

    2017-09-01

    Due to the high cost of pure CO2, carbonation of MSWI fly ash has not been fully developed. It is essential to select a kind of reaction gas with rich CO2 instead of pure CO2. The CO2 uptake and leaching toxicity of heavy metals in three typical types of municipal solid waste incinerator (MSWI) fly ash were investigated with simulated oxy-fuel combustion flue gas under different reaction temperatures, which was compared with both pure CO2 and simulated air combustion flue gas. The CO2 uptake under simulated oxy-fuel combustion flue gas were similar to that of pure CO2. The leaching concentration of heavy metals in all MSWI fly ash samples, especially in ash from Changzhou, China (CZ), decreased after carbonation. Specifically, the leached Pb concentration of the CZ MSWI fly ash decreased 92% under oxy-fuel combustion flue gas, 95% under pure CO2 atmosphere and 84% under the air combustion flue gas. After carbonation, the leaching concentration of Pb was below the Chinese legal limit. The leaching concentration of Zn from CZ sample decreased 69% under oxy-fuel combustion flue gas, which of Cu, As, Cr and Hg decreased 25%, 33%, 11% and 21%, respectively. In the other two samples of Xuzhou, China (XZ) and Wuhan, China (WH), the leaching characteristics of heavy metals were similar to the CZ sample. The speciation of heavy metals was largely changed from the exchangeable to carbonated fraction because of the carbonation reaction under simulated oxy-fuel combustion flue gas. After carbonation reaction, most of heavy metals bound in carbonates became more stable and leached less. Therefore, oxy-fuel combustion flue gas could be a low-cost source for carbonation of MSWI fly ash. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Hot Gas Cleanup Test Facility for gasification and pressurized combustion. Quarterly report, October--December 1994

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-02-01

    The objective of this project is to evaluate hot gas particle control technologies using coal-derived gas streams. This will entail the design, construction, installation, and use of a flexible test facility which can operate under realistic gasification and combustion conditions. The major particulate control device issues to be addressed include the integration of the particulate control devices into coal utilization systems, on-line cleaning techniques, chemical and thermal degradation of components, fatigue or structural failures, blinding, collection efficiency as a function of particle size, and scale-up of particulate control systems to commercial size. The conceptual design of the facility was extended to include a within scope, phased expansion of the existing Hot Gas Cleanup Test Facility Cooperative Agreement to also address systems integration issues of hot particulate removal in advanced coal-based power generation systems. This expansion included the consideration of the following modules at the test facility in addition to the original Transport Reactor gas source and Hot Gas Cleanup Units: carbonizer/pressurized circulating fluidized bed gas source; hot gas cleanup units to mate to all gas streams; combustion gas turbine; and fuel cell and associated gas treatment. The major emphasis during this reporting period was continuing the detailed design of the facility and integrating the particulate control devices (PCDs) into structural and process designs. Substantial progress in underground construction activities was achieved during the quarter. Delivery and construction of coal handling and process structural steel began during the quarter. Delivery and construction of coal handling and process structural steel began during the quarter. MWK equipment at the grade level and the first tier are being set in the structure.

  7. Thermally reduced kaolin-graphene oxide nanocomposites for gas sensing

    Science.gov (United States)

    Zhang, Renyun; Alecrim, Viviane; Hummelgård, Magnus; Andres, Britta; Forsberg, Sven; Andersson, Mattias; Olin, Håkan

    2015-01-01

    Highly sensitive graphene-based gas sensors can be made using large-area single layer graphene, but the cost of large-area pure graphene is high, making the simpler reduced graphene oxide (rGO) an attractive alternative. To use rGO for gas sensing, however, require a high active surface area and slightly different approach is needed. Here, we report on a simple method to produce kaolin-graphene oxide (GO) nanocomposites and an application of this nanocomposite as a gas sensor. The nanocomposite was made by binding the GO flakes to kaolin with the help of 3-Aminopropyltriethoxysilane (APTES). The GO flakes in the nanocomposite were contacting neighboring GO flakes as observed by electron microscopy. After thermal annealing, the nanocomposite become conductive as showed by sheet resistance measurements. Based on the conductance changes of the nanocomposite films, electrical gas sensing devices were made for detecting NH3 and HNO3. These devices had a higher sensitivity than thermally annealed multilayer GO films. This kaolin-GO nanocomposite might be useful in applications that require a low-cost material with large conductive surface area including the demonstrated gas sensors.

  8. Cytochrome c biosensor--a model for gas sensing.

    Science.gov (United States)

    Hulko, Michael; Hospach, Ingeborg; Krasteva, Nadejda; Nelles, Gabriele

    2011-01-01

    This work is about gas biosensing with a cytochrome c biosensor. Emphasis is put on the analysis of the sensing process and a mathematical model to make predictions about the biosensor response. Reliable predictions about biosensor responses can provide valuable information and facilitate biosensor development, particularly at an early development stage. The sensing process comprises several individual steps, such as phase partition equilibrium, intermediate reactions, mass-transport, and reaction kinetics, which take place in and between the gas and liquid phases. A quantitative description of each step was worked out and finally combined into a mathematical model. The applicability of the model was demonstrated for a particular example of methanethiol gas detection by a cytochrome c biosensor. The model allowed us to predict the optical readout response of the biosensor from tabulated data and data obtained in simple liquid phase experiments. The prediction was experimentally verified with a planar three-electrode electro-optical cytochrome c biosensor in contact with methanethiol gas in a gas tight spectroelectrochemical measurement cell.

  9. Investigation of gas sensing properties of InN nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Madapu, Kishore K., E-mail: madupu@igcar.gov.in, E-mail: dhara@igcar.gov.in; Prasad, A. K.; Tyagi, A. K.; Dhara, S., E-mail: madupu@igcar.gov.in, E-mail: dhara@igcar.gov.in [Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India)

    2015-06-24

    InN nanoparticles were grown by chemical vapor deposition technique using In{sub 2}O{sub 3} as precursor material. Raman spectroscopic studies show the presence of the wurtzite phase of as-grown InN. Size of the nanoparticles were in range from quantum dot (<8 nm) to larger sized particles (100 nm). We studied the gas sensing properties of InN nanoparticles with CH{sub 4} gas. Sensors substrates were fabricated with interdigitated Au electrodes. InN nanoparticles show high response towards CH{sub 4} with minimum detectable concentration of 50 ppm at 200 °C.

  10. A study on reduced chemical mechanisms of ammonia/methane combustion under gas turbine conditions

    OpenAIRE

    Xiao, Hua; Howard, Michael; Valera Medina, Agustin; Dooley, Stephen; Bowen, Philip John

    2016-01-01

    As an alternative fuel and hydrogen carrier, ammonia is believed to have good potential for future power generation. To explore the feasibility of co-firing ammonia with methane, studies involving robust numerical analyses with detailed chemistry are required to progress towards industrial implementation. Therefore, the objective of this study is to determine a reduced mechanism for simulation studies of ammonia/methane combustion in practical gas turbine combustor conditions. Firstly, five d...

  11. The combustion system of the MAN 20V35/44G gas engine

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Markus; Auer, Matthias; Stiesch, Gunnnar [MAN Diesel and Turbo SE, Augsburg (Germany)

    2013-05-15

    The new gas engine 20V35/44G by MAN Diesel and Turbo SE has a power output of 10.6 MW. The high effective efficiency level of 48.4 % as well as numerous technical innovations allow an environmentally-friendly, economical and reliable engine operation. Key to achieve this is the combustion system, which has been optimised during advanced engineering by means of modern simulation tools and extensive single-cylinder tests. (orig.)

  12. Decoration of vertical graphene with aerosol nanoparticles for gas sensing

    Science.gov (United States)

    Cui, Shumao; Guo, Xiaoru; Ren, Ren; Zhou, Guihua; Chen, Junhong

    2015-08-01

    A facile method was demonstrated to decorate aerosol Ag nanoparticles onto vertical graphene surfaces using a mini-arc plasma reactor. The vertical graphene was directly grown on a sensor electrode using a plasma-enhanced chemical vapor deposition (PECVD) method. The aerosol Ag nanoparticles were synthesized by a simple vapor condensation process using a mini-arc plasma source. Then, the nanoparticles were assembled on the surface of vertical graphene through the assistance of an electric field. Based on our observation, nonagglomerated Ag nanoparticles formed in the gas phase and were assembled onto vertical graphene sheets. Nanohybrids of Ag nanoparticle-decorated vertical graphene were characterized for ammonia gas detection at room temperature. The vertical graphene served as the conductance channel, and the conductance change upon exposure to ammonia was used as the sensing signal. The sensing results show that Ag nanoparticles significantly improve the sensitivity, response time, and recovery time of the sensor.

  13. EXPERIMENTAL STUDY AND COMPUTATIONAL MODELLING OF GAS FIRED PULSE COMBUSTION

    Directory of Open Access Journals (Sweden)

    I. Smajevic

    2010-06-01

    Full Text Available The paper presents some results of computational modelling of a gas-fired pulse combustor with aerodynamic valves. The development of the model followed experimental investigations during which the combustor geometry and operating conditions were defined. A simple 'tank and tube' approach was adopted by decomposing the combustor into several elements which were modelled separately, together with the interconnecting processes. The solution was obtained by marching integration in time over several cycles. The model reproduced reasonably well the recorded time history and averaged values of all basic parameters and is expected to complement the experiments aiming to develop a pulse combustor as a device for to cleaning the outer sides of power plants’ boiler heating surfaces during operation.

  14. Silicon Nanowire‐Based Devices for Gas-Phase Sensing

    Directory of Open Access Journals (Sweden)

    Anping Cao

    2013-12-01

    Full Text Available Since their introduction in 2001, SiNW-based sensor devices have attracted considerable interest as a general platform for ultra-sensitive, electrical detection of biological and chemical species. Most studies focus on detecting, sensing and monitoring analytes in aqueous solution, but the number of studies on sensing gases and vapors using SiNW-based devices is increasing. This review gives an overview of selected research papers related to the application of electrical SiNW-based devices in the gas phase that have been reported over the past 10 years. Special attention is given to surface modification strategies and the sensing principles involved. In addition, future steps and technological challenges in this field are addressed.

  15. Effectiveness of oxygen enriched hydrogen-HHO gas addition on DI diesel engine performance, emission and combustion characteristics

    National Research Council Canada - National Science Library

    Premkartikkumar S.R; Annamalai K; Pradeepkumar A.R

    2014-01-01

    Nowadays, more researches focus on protecting the environment. Present investigation concern with the effectiveness of Oxygen Enriched hydrogen- HHO gas addition on performance, emission and combustion characteristics of a DI diesel engine...

  16. Experimental and Numerical Research of a Novel Combustion Chamber for Small Gas Turbine Engines

    Directory of Open Access Journals (Sweden)

    Hybl R.

    2013-04-01

    Full Text Available New combustion chamber concept (based on burner JETIS-JET Induced Swirl for small gas turbine engine (up to 200kW is presented in this article. The combustion chamber concept is based on the flame stabilization by the generated swirl swirl generated by two opposite tangentially arranged jet tubes in the intermediate zone, this arrangement replaces air swirler, which is very complicated and expensive part in the scope of small gas turbines with annular combustion chamber. The mixing primary jets are oriented partially opposite to the main exhaust gasses flow, this enhances hot product recirculation and fuel-air mixing necessary for low NOx production and flame stability. To evaluate the designed concept a JETIS burner demonstrator (methane fuel was manufactured and atmospheric experimental measurements of CO, NOx for various fuel nozzles and jet tubes the configuration were done. Results of these experiments and comparison with CFD simulation are presented here. Practical application of the new chamber concept in small gas turbine liquid fuel combustor was evaluated (verified on 3 nozzles planar combustor sector test rig at atmospheric conditions results of the experiment and numerical simulation are also presented.

  17. Modeling absorption spectra for detection of the combustion products of jet engines by laser remote sensing.

    Science.gov (United States)

    Voitsekhovskaya, Olga K; Kashirskii, Danila E; Egorov, Oleg V; Shefer, Olga V

    2016-05-10

    The absorption spectra of exhaust gases (H2O, CO, CO2, NO, NO2, and SO2) and aerosol (soot and Al2O3) particles were modeled at different temperatures for the first time and suitable spectral ranges were determined for conducting laser remote sensing of the combustion products of jet engines. The calculations were conducted on the basis of experimental concentrations of the substances and the sizes of the aerosol particles. The temperature and geometric parameters of jet engine exhausts were also taken from the literature. The absorption spectra were obtained via the line-by-line method, making use of the spectral line parameters from the authors' own high-temperature databases (for NO2 and SO2 gases) and the HITEMP 2010 database, and taking into account atmospheric transmission. Finally, the theoretical absorption spectra of the exhaust gases were plotted at temperatures of 400, 700, and 1000 K, and the impact of aerosol particles on the total exhaust spectra was estimated in spectral ranges suitable for remote sensing applications.

  18. Experimental Investigation and Numerical Prediction of Thermo-acoustic Instabilities and Associated Liner Vibrations Induced by Combustion Process in Gas Turbines

    NARCIS (Netherlands)

    Pozarlik, A.K.; Kok, J.B.W.

    2012-01-01

    In this paper, lean premixed combustion on natural gas is studied in experimental and numerical way. Experiments are done at the state-of-the-art 500 kW thermal power combustion setup. The test rig resembles combustion chamber of gas turbine and can be pressurised up to 5 bar absolute pressure. The

  19. Effect of oxygen enrichment in air on acid gas combustion under Claus conditions

    KAUST Repository

    Ibrahim, Salisu

    2013-09-01

    Results are presented to examine the combustion of acid gas (H2S and CO2) in hydrogen-fueled flames using a mixture of oxygen and nitrogen under Claus conditions (Φ = 3). Specifically the effect of oxygen enrichment in the above flames is examined. The compositions of acid gas examined are100% H2S and 50% H2S/50% CO2 with different percentages of oxygen enrichment (0%, 19.3% and 69.3%) in the oxygen/nitrogen mixtures. The results revealed that combustion of acid gas formed SO2 wherein the mole fraction of SO2 increased to an asymptotic value at all the oxygen concentrations examined. In addition, increase in oxygen enrichment of the air resulted in increased amounts of SO2 rather than the formation of more desirable elemental sulfur. In case of 50% H2S/50% CO2 acid gas, carbon monoxide mole fraction increased with oxygen enrichment which is an indicator to the availability of additional amounts of oxygen into the reaction pool. This gas mixture resulted in the formation of other sulfurous–carbonaceous compounds (COS and CS2) due to the presence of carbon monoxide. The results showed that the rate of COS formation increased with oxygen enrichment due to the availability of higher amounts of CO while that of CS2 reduced. The global reactions responsible for this observed phenomenon are presented.

  20. Zinc oxide doped graphene oxide films for gas sensing applications

    Science.gov (United States)

    Chetna, Kumar, Shani; Garg, A.; Chowdhuri, A.; Dhingra, V.; Chaudhary, S.; Kapoor, A.

    2016-05-01

    Graphene Oxide (GO) is analogous to graphene, but presence of many functional groups makes its physical and chemical properties essentially different from those of graphene. GO is found to be a promising material for low cost fabrication of highly versatile and environment friendly gas sensors. Selectivity, reversibility and sensitivity of GO based gas sensor have been improved by hybridization with Zinc Oxide nanoparticles. The device is fabricated by spin coating of deionized water dispersed GO flakes (synthesized using traditional hummer's method) doped with Zinc Oxide on standard glass substrate. Since GO is an insulator and functional groups on GO nanosheets play vital role in adsorbing gas molecules, it is being used as an adsorber. Additionally, on being exposed to certain gases the electric and optical characteristics of GO material exhibit an alteration in behavior. For the conductivity, we use Zinc Oxide, as it displays a high sensitivity towards conduction. The effects of the compositions, structural defects and morphologies of graphene based sensing layers and the configurations of sensing devices on the performances of gas sensors were investigated by Raman Spectroscopy, X-ray diffraction(XRD) and Keithley Sourcemeter.

  1. Nanocasting synthesis and gas-sensing behavior of hematite nanowires

    Science.gov (United States)

    Li, Danping; Zhang, Y.; Xu, Jingcai; Jin, Hongxiao; Jin, Dingfeng; Hong, Bo; Peng, Xiaoling; Wang, Panfeng; Ge, Hongliang; Wang, Xinqing

    2016-10-01

    The dispersed and uniform hematite nanowires (α-Fe2O3 NWs) with the different diameter were synthesized using SBA-15 as hard templates by the nanocasting method, and the diameter of α-Fe2O3 NWs was about 4, 6 and 8 nm, respectively. The BET surface area of α-Fe2O3 NWs changed a little, while the bandgap decreased from 2.07, 2.03 to 1.91 eV with the increasing diameter according to quantum size effect. Compared all samples, the sensitivity of α-Fe2O3 NWs based gas-sensors increased from 10.64 to 11.43 with the bandgap and BET surface area α-Fe2O3 NWs in 100 ppm ethanol at 300 °C, and the response-recovery time was also improved for the good crystallinity. It's concluded that the surface area greatly affected the gas-sensing performance of α-Fe2O3 NWs based sensors, while the bandgap and crystallinity also influenced the gas-sensing behavior to some extent. The α-Fe2O3 NWs based gas-sensors exhibited the high sensitivity, fast response-recovery and good selectivity to ethanol.

  2. Microstructure actuation and gas sensing by the Knudsen thermal force

    Science.gov (United States)

    Strongrich, Andrew; Alexeenko, Alina

    2015-11-01

    The generation of forces and moments on structures immersed in rarefied non-isothermal gas flows has received limited practical implementation since first being discovered over a century ago. The formation of significant thermal stresses requires both large thermal gradients and characteristic dimensions which are comparable to the gas molecular mean free path. For macroscopic geometries, this necessitates impractically high temperatures and very low pressures. At the microscale, however, these conditions are easily achieved, allowing the effects to be exploited, namely, for gas-property sensing and microstructure actuation. In this letter, we introduce and experimentally evaluate performance of a microelectromechanical in-plane Knudsen radiometric actuator, a self-contained device having Knudsen thermal force generation, sensing, and tuning mechanisms integrated onto the same platform. Sensitivity to ambient pressure, temperature gradient, as well as gas composition is demonstrated. Results are presented in terms of a non-dimensional force coefficient, allowing measurements to be directly compared to the previous experimental and computational data on out-of-plane cantilevered configurations.

  3. Zinc oxide doped graphene oxide films for gas sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Chetna,, E-mail: chetna2288@gmail.com; Kumar, Shani; Chaudhary, S.; Kapoor, A. [Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021 (India); Garg, A.; Chowdhuri, A.; Dhingra, V. [Department of Electronic Science, Acharya Narendra Dev College, University of Delhi, Kalkaji, New Delhi- 110019 (India)

    2016-05-06

    Graphene Oxide (GO) is analogous to graphene, but presence of many functional groups makes its physical and chemical properties essentially different from those of graphene. GO is found to be a promising material for low cost fabrication of highly versatile and environment friendly gas sensors. Selectivity, reversibility and sensitivity of GO based gas sensor have been improved by hybridization with Zinc Oxide nanoparticles. The device is fabricated by spin coating of deionized water dispersed GO flakes (synthesized using traditional hummer’s method) doped with Zinc Oxide on standard glass substrate. Since GO is an insulator and functional groups on GO nanosheets play vital role in adsorbing gas molecules, it is being used as an adsorber. Additionally, on being exposed to certain gases the electric and optical characteristics of GO material exhibit an alteration in behavior. For the conductivity, we use Zinc Oxide, as it displays a high sensitivity towards conduction. The effects of the compositions, structural defects and morphologies of graphene based sensing layers and the configurations of sensing devices on the performances of gas sensors were investigated by Raman Spectroscopy, X-ray diffraction(XRD) and Keithley Sourcemeter.

  4. Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber

    KAUST Repository

    Shi, Xian

    2017-01-05

    Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber are numerically investigated using an 1-D unsteady, shock-capturing, compressible and reacting flow solver. Different combinations of reaction front propagation and end-gas combustion modes are observed, i.e., 1) deflagration without end-gas combustion, 2) deflagration to end-gas autoignition, 3) deflagration to end-gas detonation, 4) developing or developed detonation, occurring in the sequence of increasing initial temperatures. Effects of ignition location and chamber size are evaluated: the asymmetric ignition is found to promote the reactivity of unburnt mixture compared to ignitions at center/wall, due to additional heating from asymmetric pressure waves. End-gas combustion occurs earlier in smaller chambers, where end-gas temperature rise due to compression heating from the deflagration is faster. According to the ξ−ε regime diagram based on Zeldovich theory, modes of reaction front propagation are primarily determined by reactivity gradients introduced by initial ignition, while modes of end-gas combustion are influenced by the total amount of unburnt mixture at the time when autoignition occurs. A transient reactivity gradient method is provided and able to capture the occurrence of detonation.

  5. An evaluation of autotrophic microbes for the removal of carbon dioxide from combustion gas streams

    Energy Technology Data Exchange (ETDEWEB)

    Apel, W.A.; Walton, M.R.; Dugan, P.R. (EG G Idaho, Inc., Idaho Falls, ID (United States). Center for Biological Processing Technology)

    1994-11-01

    Carbon dioxide is a greenhouse gas that is believed to be a major contributor to global warming. Studies have shown that significant amounts of CO[sub 2] are released into the atmosphere as a result of fossil fuels combustion. Therefore, considerable interest exists in effective and economical technologies for the removal of CO[sub 2] from fossil fuel combustion gas streams. This work evaluated the use of autotrophic microbes for the removal of CO[sub 2] from coal fired power plant combustion gas streams. The CO[sub 2] removal rates of the following autotrophic microbes were determined: [ital Chlorella pyrenoidosa], [ital Euglena gracilis], [ital Thiobacillus ferrooxidans], [ital Aphanocapsa delicatissima], [ital Isochrysis galbana], [ital Phaodactylum tricornutum], [ital Navicula tripunctata schizonemoids], [ital Gomphonema parvulum], [ital Surirella ovata ovata], and four algal consortia. Of those tested, [ital Chlorella pyrenoidosa] exhibited the highest removal rate with 2.6 g CO[sub 2] per day per g dry weight of biomass being removed under optimized conditions. Extrapolation of these data indicated that to remove CO[sub 2] from the combustion gases of a coal fired power plant burning 2.4 x 10[sup 4] metric tons of coal per day would require a bioreactor 386 km[sup 2] x 1m deep and would result in the production of 2.13 x 10[sup 5] metric tons (wet weight) of biomass per day. Based on these calculations, it was concluded that autotrophic CO[sub 2] removal would not be feasible at most locations, and as a result, alternate technologies for CO[sub 2] removal should be explored. 14 refs., 7 figs., 2 tabs.

  6. Palladium Decorated Graphene-Nanoribbon Network for Enhanced Gas Sensing.

    Science.gov (United States)

    Kuru, Cihan; Choi, Duyoung; Choi, Chulmin; Kim, Young Jin; Jin, Sungho

    2015-03-01

    The fabrication of large-scale graphene nanoribbon (GNR) network and its application for gas sensing are reported. A large area, nanoscale GNR network was produced by a facile approach of silver nanowires (Ag NWs) templated graphene masking and subsequent 02 plasma etching. GNR network shows significantly enhanced sensitivity to ammonia gas compared to pristine graphene layer. The gas detection sensitivity of the nanoscale GNR network is even further improved by decorating GNR network with palladium (Pd) or platinum (Pt) nanoparticles, which show a relative resistance response of 65% and 45%, respectively to 50 ppm (parts per million) of ammonia (NH3) in nitrogen (N2) at room temperature as well as good reversibility in air.

  7. Combustion of Methane and Biogas Fuels in Gas Turbine Can-type Combustor Model

    Directory of Open Access Journals (Sweden)

    A. Guessab

    2016-01-01

    Full Text Available The paper presents the numerical simulation on combustion of methane and biogas mixtures in the swirl burner can-Type of gas turbine combustion chamber. The study deals with the impact of mass fraction of carbon dioxide for biogas on emissions of noxious compounds during combustion. The investigations were done for four different fuels: pure methane (100% CH4, three biogases (90%CH4+10%CO2, 75%CH4+25%CO2 and 70%CH4+30%CO2, with the constant value of equivalence ratio ( = 0.95. The numerical results show that a low content of carbon dioxide in methane-air mixture leads to a better flame stability through an increase of the volume of the recirculation zone. The numerical analysis has shown that the biogas fuel allows a reduction of about 33% on the NO emissions and about 10% on the CO emissions and carbon dioxide contained in the fuel leads to the lowering of the flame temperature, whose effect reduces NO emissions. The results of the investigation clearly demonstrate that it is possible to use such fuels in combustion systems with swirl burners.

  8. Numerical and experimental investigation on the performance of lean burn catalytic combustion for gas turbine application

    Science.gov (United States)

    Yin, Juan; Weng, Yi-wu; Zhu, Jun-qiang

    2015-04-01

    This manuscript presents our numerical and experimental results regarding the performance characteristics of lean burn catalytic combustion for gas turbine application. The reactant transport was assumed to be controlled by both bulk diffusion as well as surface kinetics, implemented by means of an approximate reaction rate equation and empirical coefficients to incorporate reaction mechanism. Experimental and numerical results were compared to examine the effects of methane mole fraction, inlet temperature, operating pressure, velocity and hydrogen species on combustion intensity. The results indicate that inlet temperature is the most significant parameter that impacts operation of the catalytic combustor and the most effective methods for improving the methane conversion are increasing the inlet temperature and increasing the methane mole fraction. Simulations from 1D heterogeneous plug flow model can capture the trend of catalytic combustion and describe the behavior of the catalytic monolith in detail. The addition of hydrogen will provide heat release by the exothermic combustion reaction so that the reactants reach a temperature at which methane oxidation can light-off.

  9. Erosion-Corrosion of Iron and Nickel Alloys at Elevated Temperature in a Combustion Gas Environment

    Energy Technology Data Exchange (ETDEWEB)

    Tylczak, Joseph [NETL

    2014-05-02

    This paper reports on the results of a study that compares the erosion-corrosion behavior of a variety of alloys (Fe- 2¼Cr 1Mo, 304 SS, 310 SS, Incoloy 800, Haynes 230 and a Fe3Al) in a combustion environment. Advanced coal combustion environments, with higher temperatures, are driving re-examination of traditional and examination of new alloys in these hostile environments. In order to simulate conditions in advanced coal combustion boilers, a special erosion apparatus was used to allow for impingement of particles under a low abrasive flux in a gaseous environment comprised of 20 % CO2, 0.05 % HCl, 77 % N2, 3 % O2, and 0.1 % SO2. Tests were conducted at room temperature and 700 °C with ~ 270 μm silica, using an impact velocity of 20 m/s in both air and the simulated combustion gas environment. The erosion-corrosion behavior was characterized by gravimetric measurements and by examination of the degraded surfaces optically and by scanning electron microscopy (SEM). At room temperature most of the alloys had similar loss rates. Not surprisingly, at 700 °C the lower chrome-iron alloy had a very high loss rate. The nickel alloys tended to have higher loss rates than the high chrome austenitic alloys.

  10. Substitutionally doped phosphorene: electronic properties and gas sensing

    Science.gov (United States)

    Suvansinpan, Nawat; Hussain, Fayyaz; Zhang, Gang; Hsin Chiu, Cheng; Cai, Yongqing; Zhang, Yong-Wei

    2016-02-01

    Phosphorene, a new elemental two-dimensional material, has attracted increasing attention owing to its intriguing electronic properties. In particular, pristine phospohorene, due to its ultrahigh surface-volume ratio and high chemical activity, has been shown to be promising for gas sensing (Abbas et al 2015 ACS Nano 9 5618). To further enhance its sensing ability, we perform first-principles calculations based on density functional theory to study substitutionally doped phosphorene with 17 different atoms, focusing on structures, energetics, electronic properties and gas sensing. Our calculations reveal that anionic X (X = O, C and S) dopants have a large binding energy and highly dispersive electronic states, signifying the formation of covalent X-P bonds and thus strong structural stability. Alkali atom (Li and Na) doping is found to donate most of the electrons in the outer s-orbital by forming ionic bonds with P, and the band gap decreases by pushing down the conduction band, suggesting that the optical and electronic properties of the doped phosphorene can be tailored. For doping with VIIIB-group (Fe, Co and Ni) elements, a strong affinity is predicted and the binding energy and charge transfer are correlated strongly with their electronegativity. By examining NO molecule adsorption, we find that these metal doped phosphorenes (MDPs) in general exhibit a significantly enhanced chemical activity compared with pristine phosphorene. Our study suggests that substitutionally doped phosphorene shows many intriguing electronic and optic properties different from pristine phosphorene and MDPs are promising in chemical applications involving molecular adsorption and desorption processes, such as materials growth, catalysis, gas sensing and storage.

  11. Development of a phenomenological cycle simulation for a natural gas-fuelled, compression-ignited, internal combustion engine

    Science.gov (United States)

    Liu, Yafeng

    Engine cycle simulations have been developed for modeling both diesel and dual fuel combustion in compression ignition engines. The primary objective of this work was to investigate the dual fuel combustion process in an engine and to better understand the processes of ignition, flame propagation, and pollutant formation in the engine. A multizone diesel combustion model was first developed to predict the diesel combustion process and emissions for diesel fueling. A phenomenological combustion model for dual fuel operation was then developed to simulate the combustion process and emissions of a micro-pilot diesel ignition natural gas fueled engine. Coupled with the chemical equilibrium reactions for emission formation (i.e., extended Zeldovich NOx mechanism, soot formation and destruction submodeling, unburned hydrocarbon emissions submodeling), models for diesel droplet evaporation, air entrainment, cylinder heat transfer, piston work, mass flow rates, flame propagation, crevice flow, and flame quenching have been combined with a thermodynamic analysis of the engine to yield instantaneous cylinder conditions, engine performance, and emissions. Parametric and comparison studies of diesel operation, dual fuel combustion, and micro-pilot combustion have been conducted. The major conclusions that can be drawn from this work include (1) diesel evaporation and air entrainment can have significant influence on the ignition and combustion processes, (2) pressure and temperature of inlet air, compression ratio, and the start of fuel injection are important engine operating and design parameters, (3) the combustion process of the mixture of natural gas and air is dominantly premixed-combustion, and (4) the processes of crevice flow and flame quenching can have a substantial impact on the dual fuel/micro-pilot combustion and emission formation processes.

  12. Calculational technique to predict combustible gas generation in sealed radioactive waste containers

    Energy Technology Data Exchange (ETDEWEB)

    Flaherty, J.E.; Fujita, A.; Deltete, C.P.; Quinn, G.J.

    1986-05-01

    Certain forms of nuclear waste, when subjected to ionizing radiation, produce combustible mixtures of gases. The production of these gases in sealed radioactive waste containers represents a significant safety concern for the handling, shipment and storage of waste. The US Nuclear Regulatory Commission (NRC) acted on this safety concern in September 1984 by publishing an information notice requiring waste generators to demonstrate, by tests or measurements, that combustible mixtures of gases are not present in radioactive waste shipments; otherwise the waste must be vented within 10 days of shipping. A task force, formed by the Edison Electric Institute to evaluate these NRC requirements, developed a calculational method to quantify hydrogen gas generation in sealed containers. This report presents the calculational method along with comparisons to actual measured hydrogen concentrations from EPICOR II liners, vented during their preparation for shipment. As a result of this, the NRC recently altered certain waste shipment Certificates-Of-Compliance to allow calculations, as well as tests and measurements, as acceptable means of determining combustible gas concentration. This modification was due in part to work described herein.

  13. Exfoliated black phosphorus gas sensing properties at room temperature

    Science.gov (United States)

    Donarelli, M.; Ottaviano, L.; Giancaterini, L.; Fioravanti, G.; Perrozzi, F.; Cantalini, C.

    2016-06-01

    Room temperature gas sensing properties of chemically exfoliated black phosphorus (BP) to oxidizing (NO2, CO2) and reducing (NH3, H2, CO) gases in a dry air carrier have been reported. To study the gas sensing properties of BP, chemically exfoliated BP flakes have been drop casted on Si3N4 substrates provided with Pt comb-type interdigitated electrodes in N2 atmosphere. Scanning electron microscopy and x-ray photoelectron spectroscopy characterizations show respectively the occurrence of a mixed structure, composed of BP coarse aggregates dispersed on BP exfoliated few layer flakes bridging the electrodes, and a clear 2p doublet belonging to BP, which excludes the occurrence of surface oxidation. Room temperature electrical tests in dry air show a p-type response of multilayer BP with measured detection limits of 20 ppb and 10 ppm to NO2 and NH3 respectively. No response to CO and CO2 has been detected, while a slight but steady sensitivity to H2 has been recorded. The reported results confirm, on an experimental basis, what was previously theoretically predicted, demonstrating the promising sensing properties of exfoliated BP.

  14. Pulse Combustor Driven Pressure Gain Combustion for High Efficiency Gas Turbine Engines

    KAUST Repository

    Lisanti, Joel

    2017-02-01

    The gas turbine engine is an essential component of the global energy infrastructure which accounts for a significant portion of the total fossil fuel consumption in transportation and electric power generation sectors. For this reason there is significant interest in further increasing the efficiency and reducing the pollutant emissions of these devices. Conventional approaches to this goal, which include increasing the compression ratio, turbine inlet temperature, and turbine/compressor efficiency, have brought modern gas turbine engines near the limits of what may be achieved with the conventionally applied Brayton cycle. If a significant future step increase in gas turbine efficiency is to be realized some deviation from this convention is necessary. The pressure gain gas turbine concept is a well established new combustion technology that promises to provide a dramatic increase in gas turbine efficiency by replacing the isobaric heat addition process found in conventional technology with an isochoric process. The thermodynamic benefit of even a small increase in stagnation pressure across a gas turbine combustor translates to a significant increase in cycle efficiency. To date there have been a variety of methods proposed for achieving stagnation pressure gains across a gas turbine combustor and these concepts have seen a broad spectrum of levels of success. The following chapter provides an introduction to one of the proposed pressure gain methods that may be most easily realized in a practical application. This approach, known as pulse combustor driven pressure gain combustion, utilizes an acoustically resonant pulse combustor to approximate isochoric heat release and thus produce a rise in stagnation pressure.

  15. A Component Prediction Method for Flue Gas of Natural Gas Combustion Based on Nonlinear Partial Least Squares Method

    Directory of Open Access Journals (Sweden)

    Hui Cao

    2014-01-01

    Full Text Available Quantitative analysis for the flue gas of natural gas-fired generator is significant for energy conservation and emission reduction. The traditional partial least squares method may not deal with the nonlinear problems effectively. In the paper, a nonlinear partial least squares method with extended input based on radial basis function neural network (RBFNN is used for components prediction of flue gas. For the proposed method, the original independent input matrix is the input of RBFNN and the outputs of hidden layer nodes of RBFNN are the extension term of the original independent input matrix. Then, the partial least squares regression is performed on the extended input matrix and the output matrix to establish the components prediction model of flue gas. A near-infrared spectral dataset of flue gas of natural gas combustion is used for estimating the effectiveness of the proposed method compared with PLS. The experiments results show that the root-mean-square errors of prediction values of the proposed method for methane, carbon monoxide, and carbon dioxide are, respectively, reduced by 4.74%, 21.76%, and 5.32% compared to those of PLS. Hence, the proposed method has higher predictive capabilities and better robustness.

  16. A component prediction method for flue gas of natural gas combustion based on nonlinear partial least squares method.

    Science.gov (United States)

    Cao, Hui; Yan, Xingyu; Li, Yaojiang; Wang, Yanxia; Zhou, Yan; Yang, Sanchun

    2014-01-01

    Quantitative analysis for the flue gas of natural gas-fired generator is significant for energy conservation and emission reduction. The traditional partial least squares method may not deal with the nonlinear problems effectively. In the paper, a nonlinear partial least squares method with extended input based on radial basis function neural network (RBFNN) is used for components prediction of flue gas. For the proposed method, the original independent input matrix is the input of RBFNN and the outputs of hidden layer nodes of RBFNN are the extension term of the original independent input matrix. Then, the partial least squares regression is performed on the extended input matrix and the output matrix to establish the components prediction model of flue gas. A near-infrared spectral dataset of flue gas of natural gas combustion is used for estimating the effectiveness of the proposed method compared with PLS. The experiments results show that the root-mean-square errors of prediction values of the proposed method for methane, carbon monoxide, and carbon dioxide are, respectively, reduced by 4.74%, 21.76%, and 5.32% compared to those of PLS. Hence, the proposed method has higher predictive capabilities and better robustness.

  17. Fully automated, gas sensing, and electronic parameter measurement setup for miniaturized nanoparticle gas sensors

    Science.gov (United States)

    Kennedy, M. K.; Kruis, F. E.; Fissan, H.; Mehta, B. R.

    2003-11-01

    In this study, a measurement setup has been designed and fabricated for the measurement of gas sensor characteristics and electronic parameters of nanostructured thin layers in the temperature range from room temperature to 450 °C in controlled gas environments. The setup consists of: (i) a gas environment chamber, (ii) a specially designed substrate and substrate holder, and (iii) control, supply, and measurement electronics. The buried geometry of the contacts is specially designed for the deposition of nanoparticles from the gas phase to guarantee uniform thin layers, and the setup can be used to make measurement on high resistivity (1010 Ω cm) nanoparticle samples. The gas inlet, operating temperature, and electronic control of the measurement system are automated by means of a personal computer. Coupling the measurements of interdependent gas sensing and electronic parameters at identical conditions, in a single setup encompassing a wide range of sensing gas levels and substrate temperatures, makes this system ideally suited for carrying out multiple measurements required for optimizing sensor configuration and understanding the size-dependent properties of nanoparticle sensors.

  18. Design and Operation of the Synthesis Gas Generator System for Reformed Propane and Glycerin Combustion

    Science.gov (United States)

    Pickett, Derek Kyle

    Due to an increased interest in sustainable energy, biodiesel has become much more widely used in the last several years. Glycerin, one major waste component in biodiesel production, can be converted into a hydrogen rich synthesis gas to be used in an engine generator to recover energy from the biodiesel production process. This thesis contains information detailing the production, testing, and analysis of a unique synthesis generator rig at the University of Kansas. Chapter 2 gives a complete background of all major components, as well as how they are operated. In addition to component descriptions, methods for operating the system on pure propane, reformed propane, reformed glycerin along with the methodology of data acquisition is described. This chapter will serve as a complete operating manual for future students to continue research on the project. Chapter 3 details the literature review that was completed to better understand fuel reforming of propane and glycerin. This chapter also describes the numerical model produced to estimate the species produced during reformation activities. The model was applied to propane reformation in a proof of concept and calibration test before moving to glycerin reformation and its subsequent combustion. Chapter 4 first describes the efforts to apply the numerical model to glycerin using the calibration tools from propane reformation. It then discusses catalytic material preparation and glycerin reformation tests. Gas chromatography analysis of the reformer effluent was completed to compare to theoretical values from the numerical model. Finally, combustion of reformed glycerin was completed for power generation. Tests were completed to compare emissions from syngas combustion and propane combustion.

  19. Reconstruction of combustion temperature and gas concentration distributions using line-of-sight tunable diode laser absorption spectroscopy

    Science.gov (United States)

    Zhang, Zhirong; Sun, Pengshuai; Pang, Tao; Xia, Hua; Cui, Xiaojuan; Li, Zhe; Han, Luo; Wu, Bian; Wang, Yu; Sigrist, Markus W.; Dong, Fengzhong

    2016-07-01

    Spatial temperature and gas concentration distributions are crucial for combustion studies to characterize the combustion position and to evaluate the combustion regime and the released heat quantity. Optical computer tomography (CT) enables the reconstruction of temperature and gas concentration fields in a flame on the basis of line-of-sight tunable diode laser absorption spectroscopy (LOS-TDLAS). A pair of H2O absorption lines at wavelengths 1395.51 and 1395.69 nm is selected. Temperature and H2O concentration distributions for a flat flame furnace are calculated by superimposing two absorption peaks with a discrete algebraic iterative algorithm and a mathematical fitting algorithm. By comparison, direct absorption spectroscopy measurements agree well with the thermocouple measurements and yield a good correlation. The CT reconstruction data of different air-to-fuel ratio combustion conditions (incomplete combustion and full combustion) and three different types of burners (one, two, and three flat flame furnaces) demonstrate that TDLAS has the potential of short response time and enables real-time temperature and gas concentration distribution measurements for combustion diagnosis.

  20. Reburning and burnout simulations of natural gas for heavy oil combustion

    Energy Technology Data Exchange (ETDEWEB)

    Celso A. Bertran; Carla S.T. Marques; Renato V. Filho [Universidade Estadual de Campinas, Campinas (Brazil). Instituto de Quimica

    2004-01-01

    Reburning and burnout simulations were carried out through PLUG code of CHEMKIN-III using a reduced mechanism, in order to determine preliminary experimental parameters for achieving maximum NOx reduction to implement the reburning technology for heavy oil combustion in pilot scale equipments in Brazil. Gas compositions at the entrance of the reburning zone were estimated by the AComb program. Simulations were performed for eight conditions in the usual range of operational parameters for natural gas reburning. The maximum NO reduction (ca. 50%) was reached with 10 and 17.5% of power via natural gas and 1.5 and 3.0% O{sub 2} excess, respectively, at 1273 K. The model predicts 250 ppm of NO, 50 ppm of CO and air mass flows in the range of about 50 130 kg/h for burnout. 18 refs., 1 fig., 2 tabs.

  1. DEVELOPMENT OF FINE PARTICULATE EMISSION FACTORS AND SPECIATION PROFILES FOR OIL AND GAS FIRED COMBUSTION SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Glenn England; Oliver Chang; Stephanie Wien

    2002-02-14

    This report provides results from the second year of this three-year project to develop dilution measurement technology for characterizing PM2.5 (particles with aerodynamic diameter smaller than 2.5 micrometers) and precursor emissions from stationary combustion sources used in oil, gas and power generation operation. Detailed emission rate and chemical speciation tests results for a gas turbine, a process heater, and a commercial oil/gas fired boiler are presented. Tests were performed using a research dilution sampling apparatus and traditional EPA methods. A series of pilot tests were conducted to identify the constraints to reduce the size of current research dilution sampler for future stack emission tests. Based on the test results, a bench prototype compact dilution sampler developed and characterized in GE EER in August 2002.

  2. Combustion characteristics of pulverized coal and air/gas premixed flame in a double swirl combustor

    Energy Technology Data Exchange (ETDEWEB)

    Kamal, M.M. [Ain Shams University, Cairo (Egypt). Faculty of Education

    2009-07-01

    An experimental work was performed to investigate the co-firing of pulverized coal and premixed gas/air streams in a double swirl combustor. The results showed that the NOx emissions are affected by the relative rates of thermal NOx formation and destruction via the pyrolysis of the fuel-N species in high temperature fuel-rich zones. Various burner designs were tested in order to vary the temperature history and the residence time across both coal and gas flames inside the furnace. It was found that by injecting the coal with a gas/air mixture as a combined central jet surrounded by a swirled air stream, a double flame envelope develops with high temperature fuel-rich conditions in between the two reaction zones such that the pyrolysis reactions to N{sub 2} are accelerated. A further reduction in the minimum NOx emissions, as well as in the minimum CO concentrations, was reported for the case where the coal particles are fed with the gas/air mixture in the region between the two swirled air streams. On the other hand, allocating the gas/air mixture around the swirled air-coal combustion zone provides an earlier contact with air and retards the NOx reduction mechanism in such a way that the elevated temperatures around the coal particles allow higher overall NOx emissions. The downstream impingement of opposing air jets was found more efficient than the impinging of particle non-laden premixed flames for effective NOx reduction. In both cases, there is an upstream flow from the stagnation region to the coal primary combustion region, but with the case of air impingement, the hot fuel-rich zone develops earlier. The optimum configuration was found by impinging all jets of air and coal-gas/air mixtures that pronounced minimum NOx and CO concentrations of 310 and 480ppm, respectively.

  3. Methanol Gas-Sensing Properties of SWCNT-MIP Composites

    Science.gov (United States)

    Zhang, Jin; Zhu, Qin; Zhang, Yumin; Zhu, Zhongqi; Liu, Qingju

    2016-11-01

    The single-walled carbon nanotube (SWCNT)-molecularly imprinted powder (MIP) composites in this paper were prepared by mixing SWCNTs with MIPs. The structure and micrograph of the as-prepared SWCNTs-MIPs samples were characterized by XRD and TEM. The gas-sensing properties were tested through indirect-heating sensors based on SWCNT-MIP composites fabricating on an alumina tube with Au electrodes and Pt wires. The results showed that the structure of SWCNTs-MIPs is of orthogonal perovskite and the average particle size of the SWCNTs-MIPs was in the range of 10-30 nm. SWCNTs-MIPs exhibit good methanol gas-sensitive properties. At 90 °C, the response to 1 ppm methanol is 19.7, and the response to the interferent is lower than 5 to the other interferent gases (ethanol, formaldehyde, toluene, acetone, ammonia, and gasoline). The response time and recovery time are 50 and 58 s, respectively.

  4. Gas sensing properties of nanocrystalline diamond at room temperature

    Directory of Open Access Journals (Sweden)

    Marina Davydova

    2014-12-01

    Full Text Available This study describes an integrated NH3 sensor based on a hydrogenated nanocrystalline diamond (NCD-sensitive layer coated on an interdigitated electrode structure. The gas sensing properties of the sensor structure were examined using a reducing gas (NH3 at room temperature and were found to be dependent on the electrode arrangement. A pronounced response of the sensor, which was comprised of dense electrode arrays (of 50 µm separation distance, was observed. The sensor functionality was explained by the surface transfer doping effect. Moreover, the three-dimensional model of the current density distribution of the hydrogenated NCD describes the transient flow of electrons between interdigitated electrodes and the hydrogenated NCD surface, that is, the formation of a closed current loop.

  5. Tunable diameter electrostatically formed nanowire for high sensitivity gas sensing

    Institute of Scientific and Technical Information of China (English)

    Alex Henning; Nandhini Swaminathan; Andrey Godkin; Gil Shalev; Iddo Amit; Yossi Rosenwaks

    2015-01-01

    We report on an electrostatically formed nanowire (EFN)-based sensor with tunable diameters in the range of 16 nm to 46 nm and demonstrate an EFN- based field-effect transistor as a highly sensitive and robust room temperature gas sensor. The device was carefully designed and fabricated using standard integrated processing to achieve the 16 nm EFN that can be used for sensing without any need for surface modification. The effective diameter for the EFN was determined using Kelvin probe force microscopy accompanied by three- dimensional electrostatic simulations. We show that the EFN transistor is capable of detecting 100 parts per million of ethanol gas with bare SiO2.

  6. Combustion characteristics of natural gas-hydrogen hybrid fuel turbulent diffusion flame

    Energy Technology Data Exchange (ETDEWEB)

    El-Ghafour, S.A.A.; El-dein, A.H.E.; Aref, A.A.R. [Mechanical Power Engineering Department, Faculty of Engineering, Suez Canal University, Port-Said (Egypt)

    2010-03-15

    Combustion characteristics of natural gas - hydrogen hybrid fuel were investigated experimentally in a free jet turbulent diffusion flame flowing into a slow co-flowing air stream. Experiments were carried out at a constant jet exit Reynolds number of 4000 and with a wide range of NG-H{sub 2} mixture concentrations, varied from 100%NG to 50%NG-50% H{sub 2} by volume. The effect of hydrogen addition on flame stability, flame length, flame structure, exhaust species concentration and pollutant emissions was conducted. Results showed that, hydrogen addition sustains a progressive improvement in flame stability and reduction in flame length, especially for relatively high hydrogen concentrations. Hydrogen-enriched flames found to have a higher combustion temperatures and reactivity than natural gas flame. Also, it was found that hydrogen addition to natural gas is an ineffective strategy for NO and CO reduction in the studied range, while a significant reduction in the %CO{sub 2} molar concentration by about 30% was achieved. (author)

  7. Wastewater off-gas to electricity: A look at energy recovery using the internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Hawkins, S.C. [Eckenfelder Inc., Greenville, SC (United States)

    1997-12-31

    Historically, publicly owned treatment works (POTWs) have not been regulated for air pollutant emissions. Federal, state, and local regulatory agencies have placed increased scrutiny on POTW volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions. In fact, the USEPA is developing Maximum Achievable Control Technology (MACT) standards for publicly owned facilities that receive and treat sewage and wastewater from residential, commercial, and industrial generators. Once promulgated, this standard will require POTWs to limit and control HAP emissions. One option available for the control of HAP emissions from wastewater facilities is the use of the internal combustion (IC) engine-generator systems to convert wastewater off-gas to energy. Single or multiple IC engines can be arranged to utilize wastewater off-gas in place of natural gas and diesel fuel to produce electricity. The electricity generated can then be used to power the treatment facility or sold to the local utility. These systems utilize an otherwise wasted energy resource while significantly reducing HAP and VOC emissions from the wastewater treatment process. This paper will discuss the principles of using the internal combustion engine for energy recovery and examine the technical and economic benefits involved with their use at POTW facilities.

  8. On the atomization and combustion of liquid biofuels in gas turbines: towards the application of biomass-derived pyrolysis oil

    NARCIS (Netherlands)

    Sallevelt, Johan Leonard Hendrik Pieter

    2015-01-01

    The combustion of liquid biofuels in gas turbines is an efficient way of generating heat and power from biomass. Gas turbines play a major role in the global energy supply and are suitable for a wide range of applications. However, biofuels generally have different properties compared to conventiona

  9. System Study of Rich Catalytic/Lean burn (RCL) Catalytic Combustion for Natural Gas and Coal-Derived Syngas Combustion Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Shahrokh Etemad; Lance Smith; Kevin Burns

    2004-12-01

    Rich Catalytic/Lean burn (RCL{reg_sign}) technology has been successfully developed to provide improvement in Dry Low Emission gas turbine technology for coal derived syngas and natural gas delivering near zero NOx emissions, improved efficiency, extending component lifetime and the ability to have fuel flexibility. The present report shows substantial net cost saving using RCL{reg_sign} technology as compared to other technologies both for new and retrofit applications, thus eliminating the need for Selective Catalytic Reduction (SCR) in combined or simple cycle for Integrated Gasification Combined Cycle (IGCC) and natural gas fired combustion turbines.

  10. A Wireless Electronic Nose System Using a Fe2O3 Gas Sensing Array and Least Squares Support Vector Regression

    Directory of Open Access Journals (Sweden)

    Yingguo Cheng

    2011-01-01

    Full Text Available This paper describes the design and implementation of a wireless electronic nose (WEN system which can online detect the combustible gases methane and hydrogen (CH4/H2 and estimate their concentrations, either singly or in mixtures. The system is composed of two wireless sensor nodes—a slave node and a master node. The former comprises a Fe2O3 gas sensing array for the combustible gas detection, a digital signal processor (DSP system for real-time sampling and processing the sensor array data and a wireless transceiver unit (WTU by which the detection results can be transmitted to the master node connected with a computer. A type of Fe2O3 gas sensor insensitive to humidity is developed for resistance to environmental influences. A threshold-based least square support vector regression (LS-SVR estimator is implemented on a DSP for classification and concentration measurements. Experimental results confirm that LS-SVR produces higher accuracy compared with artificial neural networks (ANNs and a faster convergence rate than the standard support vector regression (SVR. The designed WEN system effectively achieves gas mixture analysis in a real-time process.

  11. Dynamic behavior of thermoacoustic combustion oscillations in a lean premixed gas-turbine model combustor with and without active control

    Science.gov (United States)

    Tsujimoto, Ryosuke; Domen, Shohei; Okuno, Yuta; Nakagaki, Yoshitake; Gotoda, Hiroshi

    2014-11-01

    We experimentally study the dynamic behavior of thermoacoustic combustion oscillations in a laboratory-scale lean premixed gas-turbine model combustor with and without active control. We adopt the delayed feedback control method based on the concept of chaos control to suppress thermoacoustic combustion oscillations. The unstable periodic orbits in the attractor of uncontrolled thermoacoustic combustion oscillations are led to the desired orbits with a small diameter of the attractor when the perturbation is switched on, resulting in the notable suppression of thermoacoustic combustion oscillations. Color-recurrence plots (Gotoda et al., Phys. Rev. E 89, 022910 (2014)) are used for characterizing the complexity of the combustion state with and without delayed feedback control.

  12. The generation of electricity by gas turbines using the catalytic combustion of low-Btu gases

    DEFF Research Database (Denmark)

    Frederiksen, O.P.; Qvale, Einar Bjørn

    1989-01-01

    Various systems for the generation of electricity by gas turbines using catalytic combustion of low-Btu gases have been investigated. Parametric studies of three configurations that are deemed to be practically feasible have been completed. It is shown that thermodynamic efficiency of these systems...... may be quite high. The system design has been made to comply with generally accepted limitations on the operation of the compressors, turbines and heat exchangers. The heat catalyst has been investigated experimentally in order to establish design information. The system design has been carried out...... on the basis of these experiments and of commonly accepted limits on the operation of the compressors, turbines, and heat exchangers...

  13. On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments

    DEFF Research Database (Denmark)

    Evseev, Vadim; Clausen, Sønnik

    2009-01-01

    Fourier Transform Infra Red (FTIR) spectroscopy techniques are known to provide reliable results for gas temperature measurements and can be comparatively easily performed on an industrial scale such as a boiler on a power plant or an exhaust of a ship engine cylinder. However temporal resolution...... is not high enough to trace fast temperature variations which are of great importance for complete combustion diagnostics. To eliminate the above mentioned shortcoming, a new IR spectroscopic-imaging system has been developed at Risø DTU. The schematic of the system is presented. Results on lab and industrial...

  14. Determination of liquid-fuel prevaporization and premixing in gas-turbine combustion chambers

    Science.gov (United States)

    Mrugalla, J.

    A semiempirical mathematical model of the evaporation and distribution of liquid fuel in the prevaporization-premixing zone of a stationary gas turbine is developed, and the predictions obtained are compared with published experimental data and with the results of photographic, suction-probe, two-focus-laser-velocimeter, and light-scattering measurements on water sprays from 65-deg hollow-cone nozzles in a wind tunnel operating at 64 m/s. Good agreement is obtained, and the applicability of the model to the design of turbine combustion chambers giving lower NO(x) and CO emissions is indicated.

  15. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Aines, Roger D.; Bourcier, William L.

    2014-08-19

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  16. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    Science.gov (United States)

    Aines, Roger D.; Bourcier, William L.

    2010-11-09

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  17. Effect of ignition timing and hydrogen fraction on combustion and emission characteristics of natural gas direct-injection engine

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An experimental study on the combustion and emission characteristics of a direct-injection spark-ignited engine fueled with natural gas/hydrogen blends under various ignition timings was conducted.The results show that ignition timing has a significant influence on engine performance,combustion and emissions.The interval between the end of fuel injection and ignition timing is a very important parameter for direct-injection natural gas engines.The turbulent flow in the combustion chamber generated by the fuel jet remains high and relative strong mixture stratification is introduced when decreasing the angle interval between the end of fuel injection and ignition timing giving fast burning rates and high thermal efficiencies.The maximum cylinder gas pressure,maximum mean gas temperature,maximum rate of pressure rise and maximum heat release rate increase with the advancing of ignition timing.However,these parameters do not vary much with hydrogen addition under specific ignition timing indicating that a small hydrogen fraction addition of less than 20% in the present experiment has little influence on combustion parameters under specific ignition timing.The exhaust HC emission decreases while the exhaust CO2 concentration increases with the advancing of ignition timing.In the lean combustion condition,the exhaust CO does not vary much with ignition timing.At the same ignition timing,the exhaust HC decreases with hydrogen addition while the exhaust CO and CO2 do not vary much with hydrogen addition.The exhaust NOx increases with the advancing of' ignition timing and the behavior tends to be more obvious at large ignition advance angle.The brake mean effective pressure and the effective thermal efficiency of natural gas/hydrogen mixture combustion increase compared with those of natural gas combustion when the hydrogen fraction is over 10%.

  18. Fast ethylamine gas sensing based on intermolecular charge-transfer complexation

    Institute of Scientific and Technical Information of China (English)

    Eun Mi Lee; Seon Young Gwon; Young A Son; Sung Hoon Kim

    2012-01-01

    We have investigated the fast ethylamine gas sensing of 2-chloro-3,5-dinitrobenzotrifluoride (CDBF) loaded poly(acrylonitrile)nanofiber based on an intermolecular charge-transfer complexation.Reversible response and recovery were achieved using alternating gas exposure.This system shows a fast ethylamine gas sensing within 0.4 s.

  19. Concept for premixed combustion of hydrogen-containing fuels in gas turbines; Konzept zur vorgemischten Verbrennung wasserstoffhaltiger Brennstoffe in Gasturbinen

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Christoph

    2012-07-19

    One of the main challenges for future gas turbines and their combustion systems is to provide fuel flexibility. The fuel range is expected to reach from the lowly reactive natural gas to highly reactive hydrogen-containing syngases. The objective of the project in which this work was pursued is to develop such a combustion system. The burner has to ensure premixed operation with an aerodynamically stabilized flame. The focus of this work is on characterizing and optimizing the operational safety of the system, but also on ensuring sufficientmixing and lowemissions. A burner and fuel injection design is achieved that leads not only to emissions far below the permissible values, but also to flashback safety for hydrogen combustion that comes close to the theoretically achievable maximum at atmospheric pressure conditions. In this design flashback due to combustion-induced vortex breakdown and wall boundary layer flashback is avoided. Flashback only takes place when the flow velocity reaches the flame velocity.

  20. Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering.

    Science.gov (United States)

    Ehn, Andreas; Zhu, Jiajian; Li, Xuesong; Kiefer, Johannes

    2017-03-01

    Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.

  1. A Single-Walled Carbon Nanotube Network Gas Sensing Device

    Directory of Open Access Journals (Sweden)

    I-Ju Teng

    2011-08-01

    Full Text Available The goal of this research was to develop a chemical gas sensing device based on single-walled carbon nanotube (SWCNT networks. The SWCNT networks are synthesized on Al2O3-deposted SiO2/Si substrates with 10 nm-thick Fe as the catalyst precursor layer using microwave plasma chemical vapor deposition (MPCVD. The development of interconnected SWCNT networks can be exploited to recognize the identities of different chemical gases by the strength of their particular surface adsorptive and desorptive responses to various types of chemical vapors. The physical responses on the surface of the SWCNT networks cause superficial changes in the electric charge that can be converted into electronic signals for identification. In this study, we tested NO2 and NH3 vapors at ppm levels at room temperature with our self-made gas sensing device, which was able to obtain responses to sensitivity changes with a concentration of 10 ppm for NO2 and 24 ppm for NH3.

  2. Contribution of solid fuel, gas combustion or tobacco smoke to indoor air pollutant concentrations in Irish and Scottish homes

    OpenAIRE

    Semple, S; Garden, C; Coggins, M; Galea, KS; Whelan, P; Cowie, H.; Sánchez-Jimenéz, A; Thorne, PS; Hurley, JF; Ayres, JG

    2011-01-01

    There are limited data describing pollutant levels inside homes that burn solid fuel within developed country settings with most studies describing test conditions or the effect of interventions. This study recruited homes in Ireland and Scotland where open combustion processes take place. Open combustion was classified as coal, peat or wood fuel burning, use of a gas cooker or stove, or where there is at least one resident smoker. 24-hour data on airborne concentrations of particulate matter...

  3. The influence of changes of combustion gas temperature during flow around the horizontal cylinder on local Nu number

    Directory of Open Access Journals (Sweden)

    M. Górska

    2009-04-01

    Full Text Available The article the influence of changes of combustion gas temperature during flow around of horizontal cylinder on local Nu number was presented. In order to test an influence of effect waste gas temperature cycle of experimental investigations were conducted. Experimental tests were carried out on a properly designed measuring cylinder furnished with a number of thermocouples embedded along the cylinder perimeter. The cylinder was made from stainless steel of known thermal conductivity, and was cooled on the outer side through a water cooling system. The cylinder was placed horizontally in a heating chamber equipped with an axially positioned gas burner fired with natural gas. Gas and air feeds were regulated with control valves, based on combustion gas analyzer data.

  4. TiO2 Nanotubes: Recent Advances in Synthesis and Gas Sensing Properties

    Directory of Open Access Journals (Sweden)

    Giorgio Sberveglieri

    2013-10-01

    Full Text Available Synthesis—particularly by electrochemical anodization-, growth mechanism and chemical sensing properties of pure, doped and mixed titania tubular arrays are reviewed. The first part deals on how anodization parameters affect the size, shape and morphology of titania nanotubes. In the second part fabrication of sensing devices based on titania nanotubes is presented, together with their most notable gas sensing performances. Doping largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes

  5. HEAT RECOVERY FROM A NATURAL GAS POWERED INTERNAL COMBUSTION ENGINE BY CO2 TRANSCRITICAL POWER CYCLE

    Directory of Open Access Journals (Sweden)

    Mahmood Farzaneh-Gord

    2010-01-01

    Full Text Available The present work provides details of energy accounting of a natural gas powered internal combustion engine and achievable work of a utilized CO2 power cycle. Based on experimental performance analysis of a new designed IKCO (Iran Khodro Company 1.7 litre natural gas powered engine, full energy accounting of the engine were carried out on various engine speeds and loads. Further, various CO2 transcritical power cycle configurations have been appointed to take advantages of exhaust and coolant water heat lost. Based on thermodynamic analysis, the amount of recoverable work obtainable by CO2 transcritical power cycles have been calculated on various engine conditions. The results show that as much as 18 kW power could be generated by the power cycle. This would be considerable amount of power especially if compared with the engine brake power.

  6. Method for Making Measurements of the Post-Combustion Residence Time in a Gas Turbine Engine

    Science.gov (United States)

    Miles, Jeffrey H (Inventor)

    2015-01-01

    A system and method of measuring a residence time in a gas-turbine engine is provided, whereby the method includes placing pressure sensors at a combustor entrance and at a turbine exit of the gas-turbine engine and measuring a combustor pressure at the combustor entrance and a turbine exit pressure at the turbine exit. The method further includes computing cross-spectrum functions between a combustor pressure sensor signal from the measured combustor pressure and a turbine exit pressure sensor signal from the measured turbine exit pressure, applying a linear curve fit to the cross-spectrum functions, and computing a post-combustion residence time from the linear curve fit.

  7. A Technical Review of Compressed Natural Gas as an Alternative Fuel for Internal Combustion Engines

    Directory of Open Access Journals (Sweden)

    Semin

    2008-01-01

    Full Text Available Natural gas is promising alternative fuel to meet strict engine emission regulations in many countries. Compressed natural gas (CNG has long been used in stationary engines, but the application of CNG as a transport engines fuel has been considerably advanced over the last decade by the development of lightweight high-pressure storage cylinders. Engine conversion technology is well established and suitable conversion equipment is readily available. For spark ignition engines there are two options, a bi-fuel conversion and use a dedicated to CNG engine. For compression ignition engines converted to run on natural gas, there are two main options discussed, there are dual-fuel engines and normal ignition can be initiated. Natural gas engines can operate at lean burn and stoichiometric conditions with different combustion and emission characteristics. In this paper, the CNG engines research and development fueled using CNG are highlighted to keep the output power, torque and emissions of natural gas engines comparable to their gasoline or diesel counterparts. The high activities for future CNG engines research and development to meet future CNG engines is recorded in the paper.

  8. Numerical Analysis of Turbulent Combustion in a Model Swirl Gas Turbine Combustor

    Directory of Open Access Journals (Sweden)

    Ali Cemal Benim

    2016-01-01

    Full Text Available Turbulent reacting flows in a generic swirl gas turbine combustor are investigated numerically. Turbulence is modelled by a URANS formulation in combination with the SST turbulence model, as the basic modelling approach. For comparison, URANS is applied also in combination with the RSM turbulence model to one of the investigated cases. For this case, LES is also used for turbulence modelling. For modelling turbulence-chemistry interaction, a laminar flamelet model is used, which is based on the mixture fraction and the reaction progress variable. This model is implemented in the open source CFD code OpenFOAM, which has been used as the basis for the present investigation. For validation purposes, predictions are compared with the measurements for a natural gas flame with external flue gas recirculation. A good agreement with the experimental data is observed. Subsequently, the numerical study is extended to syngas, for comparing its combustion behavior with that of natural gas. Here, the analysis is carried out for cases without external flue gas recirculation. The computational model is observed to provide a fair prediction of the experimental data and predict the increased flashback propensity of syngas.

  9. Combustion Stability of the Gas Generator Assembly from J-2X Engine E10001 and Powerpack Tests

    Science.gov (United States)

    Hulka, J. R.; Kenny, R. L.; Casiano, M. J.

    2013-01-01

    Testing of a powerpack configuration (turbomachinery and gas generator assembly) and the first complete engine system of the liquid oxygen/liquid hydrogen propellant J-2X rocket engine have been completed at the NASA Stennis Space Center. The combustion stability characteristics of the gas generator assemblies on these two systems are of interest for reporting since considerable effort was expended to eliminate combustion instability during early development of the gas generator assembly with workhorse hardware. Comparing the final workhorse gas generator assembly development test data to the powerpack and engine system test data provides an opportunity to investigate how the nearly identical configurations of gas generator assemblies operate with two very different propellant supply systems one the autonomous pressure-fed test configuration on the workhorse development test stand, the other the pump-fed configurations on the powerpack and engine systems. The development of the gas generator assembly and the elimination of the combustion instability on the pressure-fed workhorse test stand have been reported extensively in the two previous Liquid Propulsion Subcommittee meetings 1-7. The powerpack and engine system testing have been conducted from mid-2011 through 2012. All tests of the powerpack and engine system gas generator systems to date have been stable. However, measureable dynamic behavior, similar to that observed on the pressure-fed test stand and reported in Ref. [6] and attributed to an injection-coupled response, has appeared in both powerpack and engine system tests. As discussed in Ref. [6], these injection-coupled responses are influenced by the interaction of the combustion chamber with a branch pipe in the hot gas duct that supplies gaseous helium to pre-spin the turbine during the start transient. This paper presents the powerpack and engine system gas generator test data, compares these data to the development test data, and provides additional

  10. Historical and future emission of hazardous air pollutants (HAPs) from gas-fired combustion in Beijing, China.

    Science.gov (United States)

    Xue, Yifeng; Nie, Lei; Zhou, Zhen; Tian, Hezhong; Yan, Jing; Wu, Xiaoqing; Cheng, Linglong

    2017-07-01

    The consumption of natural gas in Beijing has increased in the past decade due to energy structure adjustments and air pollution abatement. In this study, an integrated emission inventory of hazardous air pollutants (HAPs) emitted from gas-fired combustion in Beijing was developed for the period from 2000 to 2014 using a technology-based approach. Future emission trends were projected through 2030 based on current energy-related and emission control policies. We found that emissions of primary HAPs exhibited an increasing trend with the rapid increase in natural gas consumption. Our estimates indicated that the total emissions of NO X , particulate matter (PM)10, PM2.5, CO, VOCs, SO2, black carbon, Pb, Cd, Hg, As, Cr, Cu, Ni, Zn, polychlorinated dibenzo-p-dioxins and dibenzofurans, and benzo[a]pyrene from gas-fired combustion in Beijing were approximately 22,422 t, 1042 t, 781 t, 19,097 t, 653 t, 82 t, 19 t, 0.6 kg, 0.1 kg, 43 kg, 52 kg, 0.3 kg, 0.03 kg, 4.3 kg, 0.6 kg, 216 μg, and 242 g, respectively, in 2014. To mitigate the associated air pollution and health risks caused by gas-fired combustion, stricter emission standards must be established. Additionally, combustion optimization and flue gas purification system could be used for lowering NO X emissions from gas-fired combustion, and gas-fired facilities should be continuously monitored based on emission limits. Graphical abstract Spatial distribution and typical live photos of gas-fired boiler in Beijing.

  11. Polycyclic aromatic hydrocarbon emissions from the combustion of alternative fuels in a gas turbine engine.

    Science.gov (United States)

    Christie, Simon; Raper, David; Lee, David S; Williams, Paul I; Rye, Lucas; Blakey, Simon; Wilson, Chris W; Lobo, Prem; Hagen, Donald; Whitefield, Philip D

    2012-06-01

    We report on the particulate-bound polycyclic aromatic hydrocarbons (PAH) in the exhaust of a test-bed gas turbine engine when powered by Jet A-1 aviation fuel and a number of alternative fuels: Sasol fully synthetic jet fuel (FSJF), Shell gas-to-liquid (GTL) kerosene, and Jet A-1/GTL 50:50 blended kerosene. The concentration of PAH compounds in the exhaust emissions vary greatly between fuels. Combustion of FSJF produces the greatest total concentration of PAH compounds while combustion of GTL produces the least. However, when PAHs in the exhaust sample are measured in terms of the regulatory marker compound benzo[a]pyrene, then all of the alternative fuels emit a lower concentration of PAH in comparison to Jet A-1. Emissions from the combustion of Jet A-1/GTL blended kerosene were found to have a disproportionately low concentration of PAHs and appear to inherit a greater proportion of the GTL emission characteristics than would be expected from volume fraction alone. The data imply the presence of a nonlinear relation between fuel blend composition and the emission of PAH compounds. For each of the fuels, the speciation of PAH compounds present in the exhaust emissions were found to be remarkably similar (R(2) = 0.94-0.62), and the results do provide evidence to support the premise that PAH speciation is to some extent indicative of the emission source. In contrast, no correlation was found between the PAH species present in the fuel with those subsequently emitted in the exhaust. The results strongly suggests that local air quality measured in terms of the particulate-bound PAH burden could be significantly improved by the use of GTL kerosene either blended with or in place of Jet A-1 kerosene.

  12. Causes of Combustion Instabilities with Passive and Active Methods of Control for practical application to Gas Turbine Engines

    Science.gov (United States)

    Cornwell, Michael D.

    Combustion at high pressure in applications such as rocket engines and gas turbine engines commonly experience destructive combustion instabilities. These instabilities results from interactions between combustion heat release, fluid mechanics and acoustics. This research explores the significant affect of unstable fluid mechanics processes in augmenting unstable periodic combustion heat release. The frequency of the unstable heat release may shift to match one of the combustors natural acoustic frequencies which then can result in significant energy exchange from chemical to acoustic energy resulting in thermoacoustic instability. The mechanisms of the fluid mechanics in coupling combustion to acoustics are very broad with many varying mechanisms explained in detail in the first chapter. Significant effort is made in understanding these mechanisms in this research in order to find commonalities, useful for mitigating multiple instability mechanisms. The complexity of combustion instabilities makes mitigation of combustion instabilities very difficult as few mitigation methods have historically proven to be very effective for broad ranges of combustion instabilities. This research identifies turbulence intensity near the forward stagnation point and movement of the forward stagnation point as a common link in what would otherwise appear to be very different instabilities. The most common method of stabilization of both premixed and diffusion flame combustion is through the introduction of swirl. Reverse flow along the centerline is introduced to transport heat and chemically active combustion products back upstream to sustain combustion. This research develops methods to suppress the movement of the forward stagnation point without suppressing the development of the vortex breakdown process which is critical to the transport of heat and reactive species necessary for flame stabilization. These methods are useful in suppressing the local turbulence at the forward

  13. Characterization of Swirl-Venturi Lean Direct Injection Designs for Aviation Gas-Turbine Combustion

    Science.gov (United States)

    Heath, Christopher M.

    2013-01-01

    Injector geometry, physical mixing, chemical processes, and engine cycle conditions together govern performance, operability and emission characteristics of aviation gas-turbine combustion systems. The present investigation explores swirl-venturi lean direct injection combustor fundamentals, characterizing the influence of key geometric injector parameters on reacting flow physics and emission production trends. In this computational study, a design space exploration was performed using a parameterized swirl-venturi lean direct injector model. From the parametric geometry, 20 three-element lean direct injection combustor sectors were produced and simulated using steady-state, Reynolds-averaged Navier-Stokes reacting computations. Species concentrations were solved directly using a reduced 18-step reaction mechanism for Jet-A. Turbulence closure was obtained using a nonlinear ?-e model. Results demonstrate sensitivities of the geometric perturbations on axially averaged flow field responses. Output variables include axial velocity, turbulent kinetic energy, static temperature, fuel patternation and minor species mass fractions. Significant trends have been reduced to surrogate model approximations, intended to guide future injector design trade studies and advance aviation gas-turbine combustion research.

  14. Novel microwave-induced combustion synthesis of SnO2 nanoparticles for selective sensing of CO using tin chloride.

    Science.gov (United States)

    Habibzadeh, Sajjad; Mortazavi, Yadollah; Khodadadi, Abbas Ali

    2010-09-01

    A novel technique of chloride solution combustion synthesis (CSCS) is employed for preparation of SnO2 nanoparticles, using SnCl4 and sorbitol as a novel precursor and a fuel, respectively. Ammonium nitrate is also used as a combustion aid. The solution combustion synthesis is a single-step and simple method for nanoparticles synthesis. However, it commonly uses nitrate precursors. In this study tin chloride is used in CSCS method for the first time, employing ammonium nitrate as a combustion aid. The nanoparticles are characterized by means of XRD, SEM, EDS and BET and applied in sensing of carbon monoxide and methane. The molar ratio of fuel plus oxidant to SnCl4 (psi) and the ratio of fuel-to-oxidant (phi) were varied in the modified CSCS technique. The smallest nanoparticles size, i.e., 3.9 nm with 220 m2 x g(-1) obtained at phi = 1 and psi = 1. The sensor fabricated based on the SnO2 nanoparticles obtained by CSCS method shows 2-3 times higher sensitivity to CO than the one obtained by the conventional sol-gel method. The CSCS sensors show high sensitivity to CO at temperatures lower than 300 degrees C, at which insignificant sensitivity to methane is observed. This makes the sensor selective to CO in presence of methane.

  15. Experimental and numerical study on combustion of baled biomass in cigar burners and effects of flue gas re-circulation

    Directory of Open Access Journals (Sweden)

    Erić Aleksandar M.

    2016-01-01

    Full Text Available The paper presents results of experimental and numerical investigation addressing combustion of baled agricultural biomass in a 50 kW experimental furnace equipped with cigar burners. Experiments performed included measurements of all parameters deemed important for mass and energy balance, as well as parameters defining quality of the combustion process. Experimental results were compared with results of numerical simulations performed with previously developed CFD model. The model takes into account complex thermo mechanical combustion processes occurring in a porous layer of biomass bales and the surrounding fluid. The combustion process and the corresponding model were deemed stationary. Comparison of experimental and numerical results obtained through research presented in this paper showed satisfactory correspondence, leading to the conclusion that the model developed could be used for analysis of different effects associated with variations in process parameters and/or structural modifications in industrial biomass facilities. Mathematical model developed was also utilized to examine the impact of flue gas recirculation on maximum temperatures in the combustion chamber. Gas recirculation was found to have positive effect on the reduction of maximum temperature in the combustion chamber, as well as on the reduction of maximum temperature zone in the chamber. The conclusions made provided valuable inputs towards prevention of biomass ash sintering, which occurs at higher temperatures and negatively affects biomass combustion process. [Projekat Ministarstva nauke Republike Srbije, br. III 42011: Development and improvement of technologies for energy efficient and environmentally sound use of several types of agricultural and forest biomass and possible utilization for cogeneration i br. TR33042: Fluidized bed combustion facility improvements as a step forward in developing energy efficient and environmentally sound waste combustion

  16. Black carbon in the Arctic: the underestimated role of gas flaring and residential combustion emissions

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2013-09-01

    Full Text Available Arctic haze is a seasonal phenomenon with high concentrations of accumulation-mode aerosols occurring in the Arctic in winter and early spring. Chemistry transport models and climate chemistry models struggle to reproduce this phenomenon, and this has recently prompted changes in aerosol removal schemes to remedy the modeling problems. In this paper, we show that shortcomings in current emission data sets are at least as important. We perform a 3 yr model simulation of black carbon (BC with the Lagrangian particle dispersion model FLEXPART. The model is driven with a new emission data set ("ECLIPSE emissions" which includes emissions from gas flaring. While gas flaring is estimated to contribute less than 3% of global BC emissions in this data set, flaring dominates the estimated BC emissions in the Arctic (north of 66° N. Putting these emissions into our model, we find that flaring contributes 42% to the annual mean BC surface concentrations in the Arctic. In March, flaring even accounts for 52% of all Arctic BC near the surface. Most of the flaring BC remains close to the surface in the Arctic, so that the flaring contribution to BC in the middle and upper troposphere is small. Another important factor determining simulated BC concentrations is the seasonal variation of BC emissions from residential combustion (often also called domestic combustion, which is used synonymously in this paper. We have calculated daily residential combustion emissions using the heating degree day (HDD concept based on ambient air temperature and compare results from model simulations using emissions with daily, monthly and annual time resolution. In January, the Arctic-mean surface concentrations of BC due to residential combustion emissions are 150% higher when using daily emissions than when using annually constant emissions. While there are concentration reductions in summer, they are smaller than the winter increases, leading to a systematic increase of

  17. Black carbon in the Arctic: the underestimated role of gas flaring and residential combustion emissions

    Science.gov (United States)

    Stohl, A.; Klimont, Z.; Eckhardt, S.; Kupiainen, K.; Shevchenko, V. P.; Kopeikin, V. M.; Novigatsky, A. N.

    2013-09-01

    Arctic haze is a seasonal phenomenon with high concentrations of accumulation-mode aerosols occurring in the Arctic in winter and early spring. Chemistry transport models and climate chemistry models struggle to reproduce this phenomenon, and this has recently prompted changes in aerosol removal schemes to remedy the modeling problems. In this paper, we show that shortcomings in current emission data sets are at least as important. We perform a 3 yr model simulation of black carbon (BC) with the Lagrangian particle dispersion model FLEXPART. The model is driven with a new emission data set ("ECLIPSE emissions") which includes emissions from gas flaring. While gas flaring is estimated to contribute less than 3% of global BC emissions in this data set, flaring dominates the estimated BC emissions in the Arctic (north of 66° N). Putting these emissions into our model, we find that flaring contributes 42% to the annual mean BC surface concentrations in the Arctic. In March, flaring even accounts for 52% of all Arctic BC near the surface. Most of the flaring BC remains close to the surface in the Arctic, so that the flaring contribution to BC in the middle and upper troposphere is small. Another important factor determining simulated BC concentrations is the seasonal variation of BC emissions from residential combustion (often also called domestic combustion, which is used synonymously in this paper). We have calculated daily residential combustion emissions using the heating degree day (HDD) concept based on ambient air temperature and compare results from model simulations using emissions with daily, monthly and annual time resolution. In January, the Arctic-mean surface concentrations of BC due to residential combustion emissions are 150% higher when using daily emissions than when using annually constant emissions. While there are concentration reductions in summer, they are smaller than the winter increases, leading to a systematic increase of annual mean Arctic

  18. Numerical and Experimental Investigation of Combustion and Knock in a Dual Fuel Gas/Diesel Compression Ignition Engine

    OpenAIRE

    Gharehghani, A.; S. M. Mirsalim; S. A. Jazayeri

    2012-01-01

    Conventional compression ignition engines can easily be converted to a dual fuel mode of operation using natural gas as main fuel and diesel oil injection as pilot to initiate the combustion. At the same time, it is possible to increase the output power by increasing the diesel oil percentage. A detailed performance and combustion characteristic analysis of a heavy duty diesel engine has been studied in dual fuel mode of operation where natural gas is used as the main fuel and diesel oil as p...

  19. Gold/polypyrrole nanorods for gas sensing application

    Science.gov (United States)

    Šetka, Milena; Drbohlavová, Jana; Vallejos, Stella; Márik, Marian; Llobet, Eduard; Hubálek, Jaromír.

    2017-06-01

    This work describes the preparation of gold/polypyrrole nanorods (AuPPy NRs) using anodized alumina oxide (AAO) template and both pulsed galvanic deposition and electropolymerization for the deposition of Au and polypyrrole (PPy) nanorods (NRs), respectively. Characterization of the whole structure after AAO etching revealed the formation of a high density of NRs along the substrate with uniform diameters of approximately 50 nm and total lengths of 700 nm, the last corresponding to 1/3 and 2/3 of the length of the Au and PPy NRs, respectively. These structures are provided of bottom/top electrodes and a heating element coupled to the backside of the substrate, and their gas sensing properties towards various concentrations of NO2 in resistive configuration are presented.

  20. Gas Sensing Properties of Ordered Mesoporous SnO2

    Directory of Open Access Journals (Sweden)

    Michael Tiemann

    2006-04-01

    Full Text Available We report on the synthesis and CO gas-sensing properties of mesoporoustin(IV oxides (SnO2. For the synthesis cetyltrimethylammonium bromide (CTABr wasused as a structure-directing agent; the resulting SnO2 powders were applied as films tocommercially available sensor substrates by drop coating. Nitrogen physisorption showsspecific surface areas up to 160 m2·g-1 and mean pore diameters of about 4 nm, as verifiedby TEM. The film conductance was measured in dependence on the CO concentration inhumid synthetic air at a constant temperature of 300 °C. The sensors show a high sensitivityat low CO concentrations and turn out to be largely insensitive towards changes in therelative humidity. We compare the materials with commercially available SnO2-basedsensors.

  1. Analysis of household ignitable liquids and their post-combustion weathered residues using compound-specific gas chromatography-combustion-isotope ratio mass spectrometry.

    Science.gov (United States)

    Schwartz, Zeland; An, Yan; Konstantynova, Kateryna I; Jackson, Glen P

    2013-12-10

    The continuing rise in home and vehicular arson cases involving the use of ignitable liquids continues to be an area of concern for criminal and civil investigators. In this study, the compound-specific δ(13)C values of various components of four flammable household chemicals were measured using a single quadrupole mass spectrometer and an isotope ratio mass spectrometer as simultaneous detectors for a gas chromatograph. Whereas compound-specific carbon isotope ratios were able to discriminate between different sources of neat (pre-combustion) ignitable liquids, analyses of the post-combustion residues were problematic. Weathering caused by combustion resulted in a significant increase in the (13)C content of specific peaks relative to the neat liquids (i.e. less negative delta values) such that the isotopic comparison of pre- and post-combustion residues resulted in fractionation ranging from 0 to +10‰. Because of the current lack of understanding of isotopic fractionation during combustion, and because of problems encountered with co-elution in the more complex samples, compound-specific IRMS does not appear to be suitable for fire debris analysis. The comparison of non-combusted or non-weathered ignitable liquids is much more reliable, especially for relatively simple mixtures, and is best suited for exclusionary purposes until such time as a comprehensive database of samples is developed. Without a measure of the population variance, one cannot presently predict the false positive identification rate for the comparison of two ignitable liquids; i.e. the probability that two random ignitable liquid samples have indistinguishable isotope ratios.

  2. Atmospheric aerosol and gas sensing using Scheimpflug lidar

    Science.gov (United States)

    Mei, Liang; Brydegaard, Mikkel

    2015-04-01

    This work presents a new lidar technique for atmospheric remote sensing based on Scheimpflug principle, which describes the relationship between nonparallel image- and object-planes[1]. When a laser beam is transmitted into the atmosphere, the implication is that the backscattering echo of the entire illuminated probe volume can be in focus simultaneously without diminishing the aperture. The range-resolved backscattering echo can be retrieved by using a tilted line scan or two-dimensional CCD/CMOS camera. Rather than employing nanosecond-pulsed lasers, cascade detectors, and MHz signal sampling, all of high cost and complexity, we have developed a robust and inexpensive atmospheric lidar system based on compact laser diodes and array detectors. We present initial applications of the Scheimpflug lidar for atmospheric aerosol monitoring in bright sunlight, with a 3 W, 808 nm CW laser diode. Kilohertz sampling rates are also achieved with applications for wind speed and entomology [2]. Further, a proof-of-principle demonstration of differential absorption lidar (DIAL) based on the Scheimpflug lidar technique is presented [3]. By utilizing a 30 mW narrow band CW laser diode emitting at around 760 nm, the detailed shape of an oxygen absorption line can be resolved remotely with an integration time of 6 s and measurement cycle of 1 minute during night time. The promising results demonstrated in this work show potential for the Scheimpflug lidar technique for remote atmospheric aerosol and gas sensing, and renews hope for robust and realistic instrumentation for atmospheric lidar sensing. [1] F. Blais, "Review of 20 years of range sensor development," Journal of Electronic Imaging, vol. 13, pp. 231-243, Jan 2004. [2] M. Brydegaard, A. Gebru, and S. Svanberg, "Super resolution laser radar with blinking atmospheric particles - application to interacting flying insects " Progress In Electromagnetics Research, vol. 147, pp. 141-151, 2014. [3] L. Mei and M. Brydegaard

  3. Development of medium-sized medium-speed lean burn spark-ignited gas engines. Analyzing local gas composition within the main combustion chamber and optimizing the design factors of a jet hole in the pre-combustion chamber; Chugata chusoku kihakunensho gas engine no kaihatsu kenkyu. Nenshoshitsunai kyokusho gas sosei no bunseki to yonenshoshitsu funko sekkei yoso no saitekika ni kansuru ichikosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Goto, S.; Sakagami, T.; Hashimoto, T. [Niigata Engineering Co. Ltd., Tokyo (Japan)

    1996-10-25

    A high-speed gas sampling method was used to analyze the local gas composition within the main combustion chamber of a lean burn gas engine with a 260 mm bore. The spatial distribution of the gas composition and changes every crank angle were studied. The optimum design of a jet hole in the pre-combustion chamber was then investigated based on these results, with the aim of reducing CO and THC concentration and increasing the thermal efficiency. The engineering findings were evaluated by means of a performance test on a 6 cylinder engine. 4 refs., 10 figs., 1 tab.

  4. Experimental study of natural gas flame structure. New tools for natural gas combustion

    Energy Technology Data Exchange (ETDEWEB)

    Bachman, J.S.; Perrin, M. [Gaz de France (GDF), 93 - Saint-Denis (France)

    1994-10-01

    Recent progress in the fields of electronics, signal processing, digital imaging, optics, especially in laser, allows a finer and easier access for studies of gaseous flows structure and flames. The good knowledge of physical and chemical characteristics of flames and the understanding of mechanisms determining their stability is fundamental for improvement of burners and development of numerical models able to predict their behaviours in different experimental configurations. Therefore, it is an essential stake for the development of natural gas used both in household and industrial applications. The first part of this paper presents the different measurement techniques used at the Gaz de France R and D division for flow visualisation (laser sheet illumination), measurements temperature (fine wire thermocouples with numerical compensation) and chemical species (CO{sub 2}, CO, NO, CH{sub 4}, O{sub 2}). Examples of applications of these methods to the study of natural gas burners are presented in a second part of the paper. The first part of this paper presents applications of these techniques to improve natural gas burners. They are used, on one hand, to develop new practical heating equipments and, on the other hand, for basic studies on industrial flames structure. Work done at CERSTA, in cooperation with the Gas Research Institute, on a model burner is presented. It deals, in particular, with the effect of confinement by a cylindrical quart on the flame structure. (authors). 22 refs., 31 figs., 1 tab.

  5. Application of a Modified Gas Chromatograph to Analyze Space Experiment Combustion Gases on Space Shuttle Mission STS-94

    Science.gov (United States)

    Coho, William K.; Weiland, Karen J.; VanZandt, David M.

    1998-01-01

    A space experiment designed to study the behavior of combustion without the gravitational effects of buoyancy was launched aboard the Space Shuttle Columbia on July 1, 1997. The space experiment, designated as Combustion Module-1 (CM-1), was one of several manifested on the Microgravity Sciences Laboratory - 1 (MSL-1) mission. The launch, designated STS-94, had the Spacelab Module as the payload, in which the MSL-1 experiments were conducted by the Shuttle crewmembers. CM-1 was designed to accommodate two different combustion experiments during MSL-1. One experiment, the Structure of Flame Balls at Low Lewis-number experiment (SOFBALL), required gas chromatography analysis to verify the composition of the known, premixed gases prior to combustion, and to determine the remaining reactant and the products resulting from the combustion process in microgravity. A commercial, off-the-shelf, dual-channel micro gas chromatograph was procured and modified to interface with the CM-1 Fluids Supply Package and the CM-1 Combustion Chamber, to accommodate two different carrier gases, each flowing through its own independent column module, to withstand the launch environment of the Space Shuttle, to accept Spacelab electrical power, and to meet the Spacelab flight requirements for electromagnetic interference (EMI) and offgassing. The GC data was down linked to the Marshall Space Flight Center for near-real time analysis, and stored on-orbit for post-flight analysis. The gas chromatograph operated successfully during the entire SOFBALL experiment and collected 309 runs. Because of the constraints imposed upon the gas chromatograph by the CM-1 hardware, system and operations, it was unable to measure the gases to the required accuracy. Future improvements to the system for a re-flight of the SOFBALL experiment are expected to enable the gas chromatograph to meet all the requirements.

  6. Hot gas cleanup test facility for gasification and pressurized combustion project. Quarterly report, October--December 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    The objective of this project is to evaluate hot gas particle control technologies using coal-derived gas streams. This will entail the design, construction, installation, and use of a flexible test facility which can operate under realistic gasification and combustion conditions. The conceptual design of the facility was extended to include a within scope, phased expansion of the existing Hot Gas Cleanup Test Facility Cooperative Agreement to also address systems integration issues of hot particulate removal in advanced coal-based power generation systems. This expansion included the consideration of the following modules at the test facility in addition to the original Transport Reactor gas source and Hot Gas Cleanup Units: Carbonizer/pressurized circulating fluidized bed gas source; hot gas cleanup units to mate to all gas streams; combustion gas turbine; and fuel cell and associated gas treatment. This expansion to the Hot Gas Cleanup Test Facility is herein referred to as the Power Systems Development Facility (PSDF). The major emphasis during this reporting period was continuing the detailed design of the facility towards completion and integrating the balance-of-plant processes and particulate control devices (PCDs) into the structural and process designs. Substantial progress in construction activities was achieved during this quarter.

  7. Studies on the Effects of Interphase Heat Exchange during Thermal Explosion in a Combustible Dusty Gas with General Arrhenius Reaction-Rate Laws

    OpenAIRE

    K. S. Adegbie; F. I. Alao

    2012-01-01

    A mathematical model for thermal explosion in a combustible dusty gas containing fuel droplets with general Arrhenius reaction-rate laws, convective and radiative heat losses, and interphase heat exchange between gas and inert solid particles is investigated. The objective of the study is to examine the effects of interphase heat exchange between the gas and solid particles on (i) ignition of reacting gas, (ii) accumulation of heat by the solid particles during combustion process (iii) evapor...

  8. Synthesis, characterization and gas sensing property of hydroxyapatite ceramic

    Indian Academy of Sciences (India)

    M P Mahabole; R C Aiyer; C V Ramakrishna; B Sreedhar; R S Khairnar

    2005-10-01

    Hydroxyapatite (HAp) biomaterial ceramic was synthesized by three different processing routes viz. wet chemical process, microwave irradiation process, and hydrothermal technique. The synthesized ceramic powders were characterized by SEM, XRD, FTIR and XPS techniques. The dielectric measurements were carried out as a function of frequency at room temperature and the preliminary study on CO gas sensing property of hydroxyapatite was investigated. The XRD pattern of the hydroxyapatite biomaterial revealed that hydroxyapatite ceramic has hexagonal structure. The average crystallite size was found to be in the range 31–54 nm. Absorption bands corresponding to phosphate and hydroxyl functional groups, which are characteristic of hydroxyapatite, were confirmed by FTIR. The dielectric constant was found to vary in the range 9–13 at room temperature. Hydroxyapatite can be used as CO gas sensor at an optimum temperature near 125°C. X-ray photoelectron spectroscopic studies showed the Ca/P ratio of 1.63 for the HAp sample prepared by chemical process. The microwave irradiation technique yielded calcium rich HAp whereas calcium deficient HAp was obtained by hydrothermal method.

  9. Reduced combustion time model for methane in gas turbine flow fields

    Institute of Scientific and Technical Information of China (English)

    Mouna Lamnaouer; Robert C. Ryder; Andreja Brankovic; Eric L. Petersen

    2009-01-01

    Computational fluid dynamics (CFD) modeling of the complex processes that occur within the burner of a gas turbine engine has become a critical step in the design process. However, due to computer limitations, it is very difficult to completely couple the fluid mechanics solver with the full combustion chemistry. Therefore, simplified chemistry models are required, and the topic of this research was to provide reduced chemistry models for CH4/O2 gas turbine flow fields to be integrated into CFD codes for the simulation of flow fields of natural gas-fueled burners. The reduction procedure for the CH4/O2 model utilized a response modeling technique wherein the full mechanism was solved over a range of temperatures, pressures, and mixture ratios to establish the response of a particular variable, namely the chemical reaction time. The conditions covered were between 1000 and 2500 K for temperature, 0.1 and 2 for equivalence ratio in air, and 0.1 and 50 atm for pressure. The kinetic time models in the form of ignition time correlations are given in Arrhenius-type formulas as functions of equivaience ratio, temperature, and pressure; or fuel-to-air ratio, temperature, and pressure. A single ignition time model was obtained for the entire range of conditions, and separate models for the low-temperature and high-temperature regions as well as for fuel-lean and rich cases were also derived. Predictions using the reduced model were verified using results from the full mechanism and empirical correlations from experiments. The models are intended for (but not limited to) use in CFD codes for flow field simulations of gas turbine combustors in which initial conditions and degree of mixedness of the fuel and air are key factors in achieving stable and robust combustion processes and acceptable emission levels. The chemical time model was utilized successfully in CFD simulations of a generic gas turbine combustor with four different cases with various levels of fuel

  10. Computational fluid dynamics analysis of a synthesis gas turbulent combustion in a round jet burner

    Science.gov (United States)

    Mansourian, Mohammad; Kamali, Reza

    2017-05-01

    In this study, the RNG-Large Eddy Simulation (RNG-LES) methodology of a synthesis gas turbulent combustion in a round jet burner is investigated, using OpenFoam package. In this regard, the extended EDC extinction model of Aminian et al. for coupling the reaction and turbulent flow along with various reaction kinetics mechanisms such as Skeletal and GRI-MECH 3.0 have been utilized. To estimate precision and error accumulation, we used the Smirinov's method and the results are compared with the available experimental data under the same conditions. As a result, it was found that the GRI-3.0 reaction mechanism has the least computational error and therefore, was considered as a reference reaction mechanism. Afterwards, we investigated the influence of various working parameters including the inlet flow temperature and inlet velocity on the behavior of combustion. The results show that the maximum burner temperature and pollutant emission are affected by changing the inlet flow temperature and velocity.

  11. Evaluating the efficiency of thermo-electric conversion of heat from gas combustion in a small-scale system with counterflow heat exchange

    Science.gov (United States)

    Minaev, S. S.; Terletskii, I. A.; Kumar, S.

    2016-07-01

    The efficiency of thermoelectric conversion of heat from gas combustion was evaluated in a small-scale system consisting of two channels with opposing gas flows and thermocouples located in the separating wall. Combustion occurred in the chamber fed with fresh mixture heated by combustion products through heat-conducting walls of the channel. In the channel walls, there were thermoelectric converters. It has been shown that in this system, the maximum conversion efficiency of heat from gas combustion may be close to the maximum efficiency of thermoelectric conversion calculated by the maximum acceptable working temperature of the hot side of the converter. This conclusion is valid in the case when the adiabatic combustion temperature of the gas mixture is below the maximum allowable operating temperature of the hot side of the thermoelectric converter. The considered system is promising for the burning of low-calorific gas mixtures and does not require additional energy for cooling the cold side of the thermoelectric converter.

  12. Simulation on Different Proportions of Coal and Natural Gas Co-combustion in a Rotary Lime Kiln

    Directory of Open Access Journals (Sweden)

    Hongyu Gu

    2011-06-01

    Full Text Available Co-combustion of coal and natural gas is a promising technology in the production of active lime. For this technology, proper fuel proportion of coal and natural gas (α is one of the key parameters that requires significant thought. By means of numerical simulation, contrast studies on co-combustion with five different fuel proportions were carried out. This paper firstly puts forward the models used to describe the system based on the actual conditions. Then, numerical simulation results were analysed in detail to illustrate the co-combustion process and the velocity and temperature distribution in the kiln. Finally, comparisons of high temperature region, char conversion, length of calcining zone, CO and NOx emission and total heat transfer rate to the material bed were made in order to make a decision on fuel proportion. Synthetically considering, α=30% is a balance between benefits and costs for the rotary lime kiln studied.

  13. Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics.

    Science.gov (United States)

    Liu, Jianqiao; Gao, Yinglin; Wu, Xu; Jin, Guohua; Zhai, Zhaoxia; Liu, Huan

    2017-08-10

    The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width.

  14. Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics

    Directory of Open Access Journals (Sweden)

    Jianqiao Liu

    2017-08-01

    Full Text Available The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width.

  15. Expansion characteristics of twin combustion gas jets with high pressure in cylindrical filling liquid chamber

    Institute of Scientific and Technical Information of China (English)

    薛晓春; 余永刚; 张琦

    2013-01-01

    To deal with the problem of how to control the interior ballistic stability in the bulk-loaded liquid propellant gun, the expansion and mixing process of the twin combustion-gas jets with high temperature and pressure in a liquid medium is studied in the cylindrical filling liquid chamber. A series of the jet expansion shapes is obtained by using a high-speed photographic system. The influences of the jet pressure on the jet expansion shape are discussed. Based on the experiments, the three-dimensional mathematical model is established. The expansion processes of the twin gas jets in the liquid medium are simulated by means of fluent to get the pressure, density, temperature, velocity contours and evolutionary process of vortices. Results show that the jet external outline and tops are all irregular. The Kelvin-Helmholtz instability is shown in the whole expansion process. The numerical simulation results of the axial displacement of the twin gas jets in liquid agree well with the experiment.

  16. Regenerable sorbents for mercury capture in simulated coal combustion flue gas.

    Science.gov (United States)

    Rodríguez-Pérez, Jorge; López-Antón, M Antonia; Díaz-Somoano, Mercedes; García, Roberto; Martínez-Tarazona, M Rosa

    2013-09-15

    This work demonstrates that regenerable sorbents containing nano-particles of gold dispersed on an activated carbon are efficient and long-life materials for capturing mercury species from coal combustion flue gases. These sorbents can be used in such a way that the high investment entailed in their preparation will be compensated for by the recovery of all valuable materials. The characteristics of the support and dispersion of gold in the carbon surface influence the efficiency and lifetime of the sorbents. The main factor that determines the retention of mercury and the regeneration of the sorbent is the presence of reactive gases that enhance mercury retention capacity. The capture of mercury is a consequence of two mechanisms: (i) the retention of elemental mercury by amalgamation with gold and (ii) the retention of oxidized mercury on the activated carbon support. These sorbents were specifically designed for retaining the mercury remaining in gas phase after the desulfurization units in coal power plants.

  17. Experimental study of cyclone combustion of wood powder for gas turbine applications

    Energy Technology Data Exchange (ETDEWEB)

    Fredriksson, J.; Kallner, P. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Energy Technology

    1993-12-31

    The objective of the present project is to study to what extent various elements in the ash, in particular Na and K, can be separated in the first stage of a two-stage combustor, with the first stage being a separation cyclone. Mass balances for the elements in the ash are determined from the fuel flow, the char collected from the cyclone bottom and particles in the combustor outlet gas. Experiments have been carried out at atmospheric pressure for wood powder feeding rates of 5-21 kg/h. The conditions in the cyclone have been kept fuel rich. The gas outlet temperature from this stage has been varied from 750 to 1150 deg C through control of the air/fuel ratio. Second stage combustion is achieved in a separate combustor. The results show that significant separation of Na and K is possible, and that the separation is improved when the cyclone temperature is kept low. At an outlet temperature of around 800 deg C about 60% of the input alkali is found in the char residue. At 1000 deg C, only 30% is separated. Mass balances show that about 80% of the ash elements in the fuel input are identified in char and fly ash. With 60% separation of Na and K the content of these elements in the gas would be less than 7 mg/kg gas for a turbine inlet temperature of 850 deg C. The total dust load would be 30-60 mg/kg gas. Ash sticking temperature tests on bottom char and fly ash show no ash sticking up to 1040 deg C. It is therefore concluded that the ash may pass through the turbine as solid particles and cause minimal deposits or corrosion. 15 refs

  18. Design and Experimentation with Sandwich Microstructure for Catalytic Combustion-Type Gas Sensors

    Directory of Open Access Journals (Sweden)

    Jun-Tao Gu

    2014-03-01

    Full Text Available The traditional handmade catalytic combustion gas sensor has some problems such as a pairing difficulty, poor consistency, high power consumption, and not being interchangeable. To address these issues, integrated double catalytic combustion of alcohol gas sensor was designed and manufactured using silicon micro-electro-mechanical systems (MEMS technology. The temperature field of the sensor is analyzed using the ANSYS finite element analysis method. In this work, the silicon oxide-PECVD-oxidation technique is used to manufacture a SiO2-Si3N2-SiO2 microstructure carrier with a sandwich structure, while wet etching silicon is used to form a beam structure to reduce the heat consumption. Thin-film technology is adopted to manufacture the platinum-film sensitive resistance. Nano Al2O3-ZrO-ThO is coated to format the sensor carrier, and the sensitive unit is dipped in a Pt-Pd catalyst solution to form the catalytic sensitive bridge arm. Meanwhile the uncoated catalyst carrier is considered as the reference unit, realizing an integrated chip based on a micro double bridge and forming sensors. The lines of the Pt thin-film resistance have been observed with an electronic microscope. The compensation of the sensitive material carriers and compensation materials have been analyzed using an energy spectrum. The results show that the alcohol sensor can detect a volume fraction between 0 and 4,500 × 10−6 and has good linear output characteristic. The temperature ranges from −20 to +40 °C. The humidity ranges from 30% to 85% RH. The zero output of the sensor is less than ±2.0% FS. The power consumption is ≤0.2 W, and both the response and recovery time are approximately 20 s.

  19. Water-gas shift (WGS) Operation of Pre-combustion CO2 Capture Pilot Plant at the Buggenum IGCC

    NARCIS (Netherlands)

    Van Dijk, H.A.J.; Damen, K.; Makkee, M.; Trapp, C.

    2014-01-01

    In the Nuon/Vattenfall CO2 Catch-up project, a pre-combustion CO2 capture pilot plant was built and operated at the Buggenum IGCC power plant, the Netherlands. The pilot consist of sweet water-gas shift, physical CO2 absorption and CO2 compression. The technology performance was verified and validat

  20. Water-gas shift (WGS) Operation of Pre-combustion CO2 Capture Pilot Plant at the Buggenum IGCC

    NARCIS (Netherlands)

    Van Dijk, H.A.J.; Damen, K.; Makkee, M.; Trapp, C.

    2014-01-01

    In the Nuon/Vattenfall CO2 Catch-up project, a pre-combustion CO2 capture pilot plant was built and operated at the Buggenum IGCC power plant, the Netherlands. The pilot consist of sweet water-gas shift, physical CO2 absorption and CO2 compression. The technology performance was verified and

  1. ANALYSIS OF TRACE-LEVEL ORGANIC COMBUSTION PROCESS EMISSIONS USING NOVEL MULTIDIMENSIONAL GAS CHROMATOGRAPHY-MASS SPECTROMETRY PROCEDURES

    Science.gov (United States)

    The paper discusses the analysis of trace-level organic combustion process emissions using novel multidimensional gas chromatography-mass spectrometry (MDGC-MS) procedures. It outlines the application of the technique through the analyses of various incinerator effluent and produ...

  2. Water-gas shift (WGS) Operation of Pre-combustion CO2 Capture Pilot Plant at the Buggenum IGCC

    NARCIS (Netherlands)

    Van Dijk, H.A.J.; Damen, K.; Makkee, M.; Trapp, C.

    2014-01-01

    In the Nuon/Vattenfall CO2 Catch-up project, a pre-combustion CO2 capture pilot plant was built and operated at the Buggenum IGCC power plant, the Netherlands. The pilot consist of sweet water-gas shift, physical CO2 absorption and CO2 compression. The technology performance was verified and validat

  3. Multi-zone modelling of partially premixed low-temperature combustion in pilot-ignited natural-gas engines

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, S. R.; inivasan, K. K.

    2010-09-14

    Detailed results from a multi-zone phenomenological simulation of partially premixed advanced-injection low-pilot-ignited natural-gas low-temperature combustion are presented with a focus on early injection timings (the beginning of (pilot) injection (BOI)) and very small diesel quantities (2-3 per cent of total fuel energy). Combining several aspects of diesel and spark ignition engine combustion models, the closed-cycle simulation accounted for diesel autoignition, diesel spray combustion, and natural-gas combustion by premixed turbulent flame propagation. The cylinder contents were divided into an unburned zone, several pilot fuel zones (or 'packets') that modelled diesel evaporation and ignition, a flame zone for natural-gas combustion, and a burned zone. The simulation predicted the onset of ignition, cylinder pressures, and heat release rate profiles satisfactorily over a wide range of BOIs (20-60° before top dead centre (before TDC)) but especially well at early BOIs. Strong coupling was observed between pilot spray combustion in the packets and premixed turbulent combustion in the flame zone and, therefore, the number of ignition centres (packets) profoundly affected flame combustion. The highest local peak temperatures (greater than 2000 K) were observed in the packets, while the flame zone was much cooler (about 1650 K), indicating that pilot diesel spray combustion is probably the dominant source of engine-out emissions of nitrogen oxide (NOx). Further, the 60° before TDC BOI yielded the lowest average peak packet temperatures (about 1720 K) compared with the 20° before TDC BOI (about 2480 K) and 40° before TDC BOI (about 2700 K). These trends support experimental NOx trends, which showed the lowest NOx emissions for the 60°, 20°, and 40° before TDC BOIs in that order. Parametric studies showed that increasing the intake charge temperature, pilot quantity, and natural-gas equivalence ratio all led to

  4. Natural gas combustion and indoor air quality in domestic premises; Combustion du gaz naturel et qualite de l'air a l'interieur des habitations

    Energy Technology Data Exchange (ETDEWEB)

    Occhio, L.; Riva, A. [Snam, (Italy); Canci, F.; Scevarolli, V. [Italgas, Torino (Italy)

    2000-07-01

    Indoor air quality depends on many factors; combustion appliances are one of the sources of emissions inside dwellings. Their installation is regulated by UNI-CIG standards which also establish the ventilation and aeration requirements needed to guarantee the safety and healthiness of the environment. In order to critically evaluate the effect on indoor air quality of using gas appliances under different operational regimes and in different types of building, Snam and Italgas have developed a research project in co-operation with Enitecnologie and Turin Polytechnic, even to provide theoretical and experimental support for standardisation activities. The results of the presented research include experimental measurements made in real buildings, mathematical modelling and analysis of Italian and international literature. The results show that use of combustion appliances has little influence on indoor air quality and does not affect people's health. (authors)

  5. Gas sensing of ruthenium implanted tungsten oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tesfamichael, T., E-mail: t.tesfamichael@qut.edu.au [Institute for Future Environments, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000 (Australia); Ahsan, M. [William A. Cook Australia, 95 Brandl Street Eight Mile Plains, Brisbane, QLD 4113 (Australia); Notarianni, M. [Institute for Future Environments, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000 (Australia); Groß, A.; Hagen, G.; Moos, R. [University of Bayreuth, Faculty of Engineering Science, Department of Functional Materials, Universitätsstr. 30, 95440 Bayreuth (Germany); Ionescu, M. [ANSTO, Institute for Environmental Research, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Bell, J. [Institute for Future Environments, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000 (Australia)

    2014-05-02

    Different amounts of Ru were implanted into thermally evaporated WO{sub 3} thin films by ion implantation. The films were subsequently annealed at 600 °C for 2 h in air to remove defects generated during the ion implantation. The Ru concentrations of four samples have been quantified by Rutherford Backscattering Spectrometry as 0.8, 5.5, 9 and 11.5 at.%. The un-implanted WO{sub 3} films were highly porous but the porosity decreased significantly after ion implantation as observed by Transmission Electron Microscopy and Scanning Electron Microscopy. The thickness of the films also decreased with increasing Ru-ion dose, which is mainly due to densification of the porous films during ion implantation. From Raman Spectroscopy two peaks at 408 and 451 cm{sup −1} (in addition to the typical vibrational peaks of the monoclinic WO{sub 3} phase) associated with Ru were observed. Their intensity increased with increasing Ru concentration. X-ray Photoelectron Spectroscopy showed a metallic state of Ru with binding energy of Ru 3d{sub 5/2} at 280.1 eV. This peak position remained almost unchanged with increasing Ru concentration. The resistances of the Ru-implanted films were found to increase in the presence of NO{sub 2} and NO with higher sensor response to NO{sub 2}. The effect of Ru concentration on the sensing performance of the films was not explicitly observed due to reduced film thickness and porosity with increasing Ru concentration. However, the results indicate that the implantation of Ru into WO{sub 3} films with sufficient film porosity and film thickness can be beneficial for NO{sub 2} sensing at temperatures in the range of 250 °C to 350 °C. - Highlights: • Densification of WO{sub 3} thin films has occurred after Ru ion implantation. • Thickness and porosity of the films decrease with increasing Ru ion dose. • The amount of oxygen vacancies and defects increases with increasing Ru ion dose. • Ru has shown a crucial role in enhancing sensor response

  6. Study for engine conversion from gasoline to natural gas by using the two-zone combustion predictive model; Estudio de la conversion del motor de gasolina a gas natural mediante modelo de combustion predictivo de dos zonas

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Espinoza; Moreno, Jesus; Perez, Andres [Universidad de Oriente, Puerto la Cruz (Venezuela). Dept. de Mecanica; Baduy, Franklin [Universidad Central de Venezuela, Caracas (Venezuela). Dept. de Termoenergetica

    1995-07-01

    Great scale conversion of automation engines is a policy used by many countries as a strategy to save gasoline. Previous studies on the effects that this transformation can have over the engine performance are required for the implantation of this type of conversion. also, modifications in components and tuning for each engine have to be analyzed. This paper studies the effect of the conversion from gasoline to natural gas over the engine output, indicate mean pressure, combustion rate etc. It also analyze how to find the starting angle and the best air/fuel ratio for a specific engine, using a two-zone combustion model. (author)

  7. Semipermeable Elastic Microcapsules for Gas Capture and Sensing.

    Science.gov (United States)

    Nabavi, Seyed Ali; Vladisavljević, Goran T; Gu, Sai; Manović, Vasilije

    2016-09-27

    Monodispersed microcapsules for gas capture and sensing were developed consisting of elastic semipermeable polymer shells of tunable size and thickness and pH-sensitive, gas selective liquid cores. The microcapsules were produced using glass capillary microfluidics and continuous on-the-fly photopolymerization. The inner fluid was 5-30 wt % K2CO3 solution with m-cresol purple, the middle fluid was a UV-curable liquid silicon rubber containing 0-2 wt % Dow Corning 749 fluid, and the outer fluid was aqueous solution containing 60-70 wt % glycerol and 0.5-2 wt % stabilizer (poly(vinyl alcohol), Tween 20, or Pluronic F-127). An analytical model was developed and validated for prediction of the morphology of the capsules under osmotic stress based on the shell properties and the osmolarity of the storage and core solutions. The minimum energy density and UV light irradiance needed to achieve complete shell polymerization were 2 J·cm(-2) and 13.8 mW·cm(-2), respectively. After UV exposure, the curing time for capsules containing 0.5 wt % Dow Corning 749 fluid in the middle phase was 30-40 min. The CO2 capture capacity of 30 wt % K2CO3 capsules was 1.6-2 mmol/g depending on the capsule size and shell thickness. A cavitation bubble was observed in the core when the internal water was abruptly removed by capillary suction, whereas a gradual evaporation of internal water led to buckling of the shell. The shell was characterized using TGA, DSC, and FTIR. The shell degradation temperature was 450-460 °C.

  8. Terahertz Active Photonic Crystals for Condensed Gas Sensing

    Directory of Open Access Journals (Sweden)

    Karl Unterrainer

    2011-06-01

    Full Text Available The terahertz (THz spectral region, covering frequencies from 1 to 10 THz, is highly interesting for chemical sensing. The energy of rotational and vibrational transitions of molecules lies within this frequency range. Therefore, chemical fingerprints can be derived, allowing for a simple detection scheme. Here, we present an optical sensor based on active photonic crystals (PhCs, i.e., the pillars are fabricated directly from an active THz quantum-cascade laser medium. The individual pillars are pumped electrically leading to laser emission at cryogenic temperatures. There is no need to couple light into the resonant structure because the PhC itself is used as the light source. An injected gas changes the resonance condition of the PhC and thereby the laser emission frequency. We achieve an experimental frequency shift of 10−3 times the center lasing frequency. The minimum detectable refractive index change is 1.6 × 10−5 RIU.

  9. Gas dependent sensing mechanism in ZnO nanobelt sensor

    Science.gov (United States)

    Kaur, Manmeet; Kailasaganapathi, S.; Ramgir, Niranjan; Datta, Niyanta; Kumar, Sushil; Debnath, A. K.; Aswal, D. K.; Gupta, S. K.

    2017-02-01

    Gas sensing properties of ZnO nanobelts synthesized using carbothermal reduction method has been investigated. At room temperature (28 °C), the sensor films exhibit an appreciable response towards H2S and NO and response of these two gases were studied as a function of concentration. For NO the sensor films exhibit a complete reversible curve for the concentration range between 1 and 60 ppm. However, for H2S a complete recovery was obtained for concentration H2S exposure. After exposure, appearance of an additional peak at 26.6° corresponding to the formation of ZnS was observed in XRD. Formation of additional phase was further corroborated using the results of XPS. H2S exposure causes decrease in the intensity of O 1s peak and appearance of sulphide peaks at binding energies of 162.8 and 161.8 eV corresponding to S-2p peaks - 2p3/2 and 2p1/2, confirms the formation of ZnS upon exposure.

  10. Experimental study of acoustic damping induced by gas-liquid scheme injectors in a combustion chamber

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hak Soon; Sohn, Chae Hoon [Chosun University, Gwangju (Korea, Republic of)

    2007-01-15

    In a liquid rocket engine, acoustic damping induced by gas-liquid scheme injectors is studied experimentally for combustion stability by adopting linear acoustic test. In the previous work, it has been found that gas-liquid scheme injector can play a significant role in acoustic damping or absorption when it is tuned finely. Based on this finding, acoustic-damping characteristics of multi-injectors are intensively investigated. From the experimental data, it is found that acoustic oscillations are almost damped out by multi-injectors when they have the tuning length proposed in the previous study. The length corresponds to a half wavelength of the first longitudinal overtone mode traveling inside the injector with the acoustic frequency intended for damping in the chamber. But, new injector-coupled acoustic modes show up in the chamber with the injectors of the tuning length although the target mode is nearly damped out. And, appreciable frequency shift is always observed except for the case of the worst tuned injector. Accordingly, it is proposed that the tuning length is adjusted to have the shorter length than a half wavelength when these phenomena are considered

  11. Fabrication, characterization and gas sensing properties of gold nanoparticle and calixarene multilayers

    Indian Academy of Sciences (India)

    IINCI ÇAPAN; ASEEL K HASSAN; RAJAA R ABBAS

    2017-02-01

    Calixarenes are a group of materials that are widely used for gas sensing studies because of their simple synthesis, conformational flexibility, binding group tunability, variability in their cavity sizes and improved selectivity to different gas molecules. In recent years it has been shown that incorporation of gold nanoparticles (AuNPs) into organic layers further enhances their gas sensing performance. The present study reports on the fabrication of thin films of calixarene and AuNPs using Langmuir–Schaefer (LS) methods. The gas sensing properties of the produced films are investigated on exposure to saturated vapours of volatile organic compounds (VOCs) using surface plasmon resonance as an optical detection technique. Multilayers comprising films of AuNPs and calixarene have been investigated to evaluate the effect of AuNPs on the films sensing performances. It has been demonstrated that the hybrid layers exhibited improved sensing performance in terms of the degree of their response.

  12. Method and device for determining heats of combustion of gaseous hydrocarbons

    Science.gov (United States)

    Singh, Jag J. (Inventor); Sprinkle, Danny R. (Inventor); Puster, Richard L. (Inventor)

    1988-01-01

    A method and device is provided for a quick, accurate and on-line determination of heats of combustion of gaseous hydrocarbons. First, the amount of oxygen in the carrier air stream is sensed by an oxygen sensing system. Second, three individual volumetric flow rates of oxygen, carrier stream air, and hydrocrabon test gas are introduced into a burner. The hydrocarbon test gas is fed into the burner at a volumetric flow rate, n, measured by a flowmeter. Third, the amount of oxygen in the resulting combustion products is sensed by an oxygen sensing system. Fourth, the volumetric flow rate of oxygen is adjusted until the amount of oxygen in the combustion product equals the amount of oxygen previously sensed in the carrier air stream. This equalizing volumetric flow rate is m and is measured by a flowmeter. The heat of combustion of the hydrocrabon test gas is then determined from the ratio m/n.

  13. Modeling the sensing characteristics of chemi-resistive thin film semi-conducting gas sensors.

    Science.gov (United States)

    Ghosh, Abhishek; Majumder, S B

    2017-08-30

    For chemi-resistive thin film gas sensors a generic theoretical model is proposed to predict the variation of sensor response with the operating temperature and thickness of the sensing film. A diffusion equation is formulated assuming that inflammable target gases move through the sensing film by Knudsen diffusion and react with the adsorbed oxygen following first-order kinetics. We have assumed a realistic non-linear variation between the conductance and test gas concentration and derived a general expression relating the sensor response to the operating temperature and thickness of the film. Assuming Langmuir adsorption kinetics, we have theoretically predicted the response and recovery transients during gas sensing using thin film sensing elements. It is predicted that for irreversible type sensing, the response time is reduced with an increase in test gas concentration, whereas for reversible sensing, the response time is independent of test gas concentration. For zinc oxide thin film sensors, an excellent match is obtained between the model prediction and experimental data for their thickness (122 nm to 380 nm) and temperature variation (200 °C to 325 °C) in 500 ppm carbon monoxide (CO) sensing. The maximum CO response% (∼53%) was achieved in 320 nm thick ZnO films. The conductance transients for response and recovery for CO sensing closely follow Langmuir adsorption kinetics and as predicted theoretically, indeed for irreversible sensing, the response time reduces from 350 s to 220 s with an increase in test gas concentration from 20 to 550 ppm. In the case of reversible sensing we found that the response time is ∼55 s irrespective of the CO gas concentration in the range of 5-500 ppm. The models developed in the present work are quite generic in nature and we have discussed their applicability to a wide variety of sensing materials with various types of surface morphologies.

  14. Effect of the Concentration of a Combustible Gas on the Limiting Critical Conditions of Its Catalytic Oxidation

    Science.gov (United States)

    Kalinchak, V. V.; Chernenko, A. S.; Kalugin, V. V.

    2015-05-01

    For the case of the cold, relative to a gas mixture, walls of an apparatus and radiation heat transfer, an investigation is made of the dependence of the limiting minimum gas mixture temperatures above which catalytic self-ignition and firing of a low-concentration combustible gas on a catalyst particle are possible. The proposed method is based on obtaining the desired dependences in a parametric form. An analysis of the degeneration of critical temperatures and of ignition and extinction diameters is carried out.

  15. The Role of Post Flame Oxidation on the UHC Emission for Combustion of Natural Gas and Hydrogen Containing fuels

    DEFF Research Database (Denmark)

    Jensen, Torben Kvist; Schramm, Jesper

    2003-01-01

    reactants from crevices and hot burned bulk gas and to describe the oxidation of the unburned fuel. The post oxidation was described by a single step chemical reaction mechanism instead of detailed chemical kinetics in order to reduce the calculation time. However, the exploited Arrhenius expressions used...... during in-cylinder post oxidation. The Arrhenius parameters were determined using the reaction mechanism, which gave the prediction of the results from the combustion reactor experiments. The investigation showed that addition of producer gas to natural gas promotes the in-cylinder post oxidation...

  16. Development of the utilization of combustible gas produced in existing sanitary landfills: Investigation of effects of air inclusion

    Science.gov (United States)

    1983-01-01

    The effects of nitrogen and oxygen on landfill gas operations are discussed. A combustible gas mixture composed of methane and carbon dioxide is generated in municipal solid waste landfills. A consequence of the collection of this fuel gas is the inclusion of some air in the collected product. The effects include increased collected and purification costs, reduction in the quality of the fuel gas produced, corrosion, explosion hazards, and interference with odorant systems. The scope of such effects was determined by using landfill data of a gas recovery site as a basis. Useful supplemental fuel gas may be recovered despite the inclusion of air. Recommendations are made for establishing limits for nitrogen and oxygen content and minimizing the costs associated with their presence.

  17. Effect of UV and vacuum treatment on stability of WO3 gas sensing films

    Science.gov (United States)

    Gao, Guohua; Wu, Guangming; Zhang, Zenghai; Wu, Jiandong; Feng, Wei; Shen, Jun; Zhang, Zhihua; Du, Ai

    2011-02-01

    UV and vacuum treatment, as well as annealing, were tried to recover the gas sensing property of WO3 films. Results show that gas sensing films can partially recover one or two coloring and bleaching cycles if kept in vacuum condition. And UV irradiation can well recover several cycles. But heat treatment does not show any obvious effect on the gas sensing recovery. Furthermore, IR and XPS spectra were used to identify the mechanism of this improvement. Results reveal that changes of water content will reduce the desorption energy of hydrogen atom, which will accelerate the bleaching velocity.

  18. Release to the Gas Phase of Inorganic Elements during Wood Combustion. Part 2: Influence of Fuel Composition

    DEFF Research Database (Denmark)

    van Lith, Simone Cornelia; Jensen, Peter Arendt; Frandsen, Flemming

    2008-01-01

    Combustion of wood for heat and power production may cause problems such as ash deposition, corrosion, and harmful emissions of gases and particulate matter. These problems are all directly related to the release of inorganic elements (in particular Cl, S, K, Na, Zn, and Pb) from the fuel...... to the gas phase. The aims of this study are to obtain quantitative data on the release of inorganic elements during wood combustion and to investigate the influence of fuel composition. Quantitative release data were obtained by pyrolyzing and subsequently combusting small samples of wood (~30 g) at various...... temperatures in the range of 500–1150 °C in a laboratory-scale tube reactor and by performing mass balance calculations based on the weight measurements and chemical analyses of the wood fuels and the residual ash samples. Four wood fuels with different ash contents and inorganic compositions were investigated...

  19. PERFORMANCE, EMISSION, AND COMBUSTION CHARACTERISTICS OF A CI ENGINE USING LIQUID PETROLEUM GAS AND NEEM OIL IN DUAL FUEL MODE

    Directory of Open Access Journals (Sweden)

    Palanimuthu Vijayabalan

    2010-01-01

    Full Text Available Increased environmental awareness and depletion of resources are driving the industries to develop viable alternative fuels like vegetable oils, compresed natural gas, liquid petroleum gas, producer gas, and biogas in order to provide suitable substitute to diesel for compression ignition engine. In this investigation, a single cylinder, vertical, air-cooled diesel engine was modified to use liquid petroleum gas in dual fuel mode. The liquefied petroleum gas, was mixed with air and supplied through intake manifold. The liquid fuel neem oil or diesel was injected into the combustion chamber. The performance, emission, and combustion characteristics were studied and compared for neat fuel and dual fuel mode. The experimental results on dual fuel engine show a reduction in oxides of nitrogen up to 70% of the rated power and smoke in the entire power range. However the brake thermal efficiency was found decreased in low power range due to lower calorific value of liquid petroleum gas, and increase in higher power range due to the complete burning of liquid petroleum gas. Hydrocarbon and carbon monoxide emissions were increased significantly at lower power range and marginal variation in higher power range.

  20. Vapor-phase combustion and heat and mass transfer during the interaction of a high-temperature gas flow with a solid

    Energy Technology Data Exchange (ETDEWEB)

    Pushkin, V.N.; Sukhov, G.S.; Iarin, L.P.

    1988-08-01

    The problem of the combustion of a solid in incoming gas flow containing an oxidizer is solved by using an analytical model allowing for phase transitions and chemical transformations and assuming a quasi-equilibrium state on the free surface and diffusion combustion at the flame front. The hydrodynamic, temperature, and concentration fields are investigated for the case of flow past a body with a spherical nose. The principal combustion characteristics are determined as a function of the incoming flow intensity. 6 references.

  1. Combustion gas cleaning in the ceramic tile industry: technical guide; Nettoyage des fumees de combustion dans l'industrie ceramique: guide technique

    Energy Technology Data Exchange (ETDEWEB)

    Lezaun, F.J. [ENAGAS-Grupo Gas Natural (Spain); Mallol, G.; Monfort, E. [instituto de Tecnologia Ceramica, ITC (Spain); Busani, G. [Agenzia Regionale per la Prevenzione e l' Amiente, ARPA (Spain)

    2000-07-01

    This document presents a summary of a technical guide drawn up on combustion gas cleaning systems in ceramic frit and tile production. The guide describes the method to be followed for selecting the best possible solutions for reducing pollutant concentrations in different emission sources, in accordance with current regulatory requirements and the CET recommendation. There are three sources of combustion gas air emissions that need to be cleaned in ceramic tile and frit production and they are usually related to the following process stages: slip spray drying, tile firing and frit melting. The different nature of the emissions means that different substances will need to be cleaned in each emission. Thus, in spray drying and frit melting, the only species to be cleaned are suspended particles, while in tile firing, it is also necessary to reduce the fluorine concentration. The systems analysed in this guide are mainly wet cleaning systems, bag filters and electrostatic precipitators. In the study, the efficiency of these cleaning systems is compared at each emission source from a technical and economic point of view, and concrete solutions are put forward in each case, together with a list of suppliers of the technologies involved. (authors)

  2. Volatilization behavior of Cd and Zn based on continuous emission measurement of flue gas from laboratory-scale coal combustion.

    Science.gov (United States)

    Liu, J; Falcoz, Q; Gauthier, D; Flamant, G; Zheng, C Z

    2010-06-01

    The accumulation of toxic metals generated by coal-fired power stations presents a serious threat to the environment. The volatilization behavior of two representative metals (Cd and Zn), and the influence of temperature were investigated during coal combustion. An inductively coupled plasma atomic emission spectrometric (ICP-AES) method was developed to continuously measure the heavy metal concentrations quantitatively in flue gas under combustion conditions in order to track the metal release process. This continuous heavy metal analysis system was implemented by coupling it to two types of high temperature reactors: a bubbling fluidized bed reactor and a fixed bed reactor with diameter of 0.1 m and 0.08 m respectively. For the two metals considered in this study (Cd and Zn), the experimental setup was successfully used to continuously monitor the metal vaporization process during coal combustion independent of reactor design, and at different temperatures. Cd is more easily vaporized than Zn during coal combustion. Temperature significantly influences the metal vaporization process. In general, the higher the temperature, the higher the metal vaporization, although the vaporization is not proportional to temperature. In addition to the experimental study, a thermodynamic calculation was carried out to simulate the heavy metal speciation during coal combustion process. The theoretical volatilization tendency is consistent with the experiment. The thermodynamic calculation identified the formation of binary oxides retarding heavy metal vaporization.

  3. CO Sensing Performance of a Micro Thermoelectric Gas Sensor with AuPtPd/SnO₂ Catalyst and Effects of a Double Catalyst Structure with Pt/α-Al₂O₃.

    Science.gov (United States)

    Goto, Tomoyo; Itoh, Toshio; Akamatsu, Takafumi; Shin, Woosuck

    2015-12-15

    The CO sensing properties of a micro thermoelectric gas sensor (micro-TGS) with a double AuPtPd/SnO₂ and Pt/α-Al₂O₃ catalyst were investigated. While several nanometer sized Pt and Pd particles were uniformly dispersed on SnO₂, the Au particles were aggregated as particles measuring >10 nm in diameter. In situ diffuse reflectance Fourier transform Infrared spectroscopy (DRIFT) analysis of the catalyst showed a CO adsorption peak on Pt and Pd, but no clear peak corresponding to the interaction between CO and Au was detected. Up to 200 °C, CO combustion was more temperature dependent than that of H₂, while H₂ combustion was activated by repeated exposure to H₂ gas during the periodic gas test. Selective CO sensing of the micro-TGS against H₂ was attempted using a double catalyst structure with 0.3-30 wt% Pt/α-Al₂O₃ as a counterpart combustion catalyst. The sensor output of the micro-TGS decreased with increasing Pt content in the Pt/α-Al₂O₃ catalyst, by cancelling out the combustion heat from the AuPtPd/SnO₂ catalyst. In addition, the AuPtPd/SnO₂ and 0.3 wt% Pt/α-Al₂O₃ double catalyst sensor showed good and selective CO detection. We therefore demonstrated that our micro-TGS with double catalyst structure is useful for controlling the gas selectivity of CO against H₂.

  4. Improved gas sensing and dielectric properties of Fe doped hydroxyapatite thick films: Effect of molar concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Mene, Ravindra U. [PDEA' s, Annasaheb Waghire College of Science, Arts and Commerce, Otur 412409, M.S. (India); School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India); Mahabole, Megha P. [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India); Mohite, K.C. [Haribhai. V. Desai College, Pune 411002, M.S. (India); Khairnar, Rajendra S., E-mail: rskhairnarsps@gmail.com [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, M.S. (India)

    2014-02-01

    Highlights: • We report improved gas sensing and dielectric characteristics of Fe ion exchanged HAp films. • Fe doped HAp film shows maximum gas response at relatively lower temperature. • Response and gas uptake capacity of sensors is improved for appropriate amount of Fe ions in HAp matrix. • Fe-HAp films exhibit remarkable improvement in dielectric properties compared to pure HAp. • Fe doped HAp films show significant improvement in gas sensing as well as in dielectric properties. - Abstract: In the present work Fe doped hydroxyapatite (Fe-HAp) thick films has been successfully utilized to improve the gas sensing as well as its dielectric properties. Initially, HAp nano powder is synthesized by chemical precipitation process and later on Fe ions are doped in HAp by ion exchange process. Structural and morphological modifications are observed by means of X-ray diffraction and scanning electron microscopy analysis. The sensing parameters such as operating temperature, response/recovery time and gas uptake capacity are experimentally determined. The Fe-HAp (0.05 M) film shows improved CO and CO{sub 2} gas sensing capacity at lower operating temperature compared to pure HAp. Moreover, variation of dielectric constant and dielectric loss for pure and Fe-HAp thick films are studied as a function of frequency in the range of 10 Hz–1 MHz. The study reveals that Fe doped HAp thick films improve the sensing and dielectric characteristics as compared to pure HAp.

  5. Numerical study of test gas vitiation effects on hydrogen-fueled scramjet combustion%Numerical study of test gas vitiation effects on hydrogen-fueled scramjet combustion

    Institute of Scientific and Technical Information of China (English)

    CHEN Chao-qun; TIAN Liang; XU Xu

    2012-01-01

    The effects of major vitiated species (H2O and CO2) and minor vitiated species (H,OH and O radicals) produced by combustion air preheater on ignition and combustion of hydrogen-fueled seramjet were numerically investigated. Firstly, kinetic analyses with CHEMKIN SENKIN code were conducted to evaluate the effects of contamination on the ignition delay times of hydrogen fuel over a range of temperature and pressure variations. Then numerical simulation of a three-dimensional reacting flow in hydrogen-fueled seramjet combustor was performed. The two-equation shear stress transport k-ω turbulence model was used for modeling turbulence and 33 reactions finite-rate chemistry was used for modeling the H2/air kinetics. The results show that: free radical species such as H,O,and OH may significantly promote the ignition process of hydrogen-air at relatively low initial temperature and pressure. However, H2O and CO2 have inhibition effects on the ignition process. Under the same conditions, H2O has more effective inhibition effects than CO2. The temperature and pressure rise due to combustion are lower in the air vitiated with H2O and CO2 because of their higher heat capacities and more dissociation. Combustion efficiency and thrust calculated for vitiated air case are lower than clean air case. These results indicate the importance of accounting for vitiation effects when extrapolating performance data from ground test to flight demonstration.

  6. 燃气锅炉使用富氧燃烧初探%Application of oxygen-combustion technology in gas - fired boiler

    Institute of Scientific and Technical Information of China (English)

    张郁; 翟强

    2012-01-01

    The point of oxygen combustion technology was described. The future of oxygen combustion technology in gas - fired boiler was analyzed.%介绍了富氧燃烧的特点,分析了在燃气锅炉中使用富氧技术的应用前景.

  7. Effectiveness of oxygen enriched hydrogen-HHO gas addition on DI diesel engine performance, emission and combustion characteristics

    Directory of Open Access Journals (Sweden)

    Premkartikkumar S.R.

    2014-01-01

    Full Text Available Nowadays, more researches focus on protecting the environment. Present investigation concern with the effectiveness of Oxygen Enriched hydrogen- HHO gas addition on performance, emission and combustion characteristics of a DI diesel engine. Here the Oxygen Enriched hydrogen-HHO gas was produced by the process of water electrolysis. When potential difference is applied across the anode and cathode electrodes of the electrolyzer, water is transmuted into Oxygen Enriched hydrogen-HHO gas. The produced gas was aspirated into the cylinder along with intake air at the flow rates of 1 lpm and 3.3 lpm. The results show that when Oxygen Enriched hydrogen-HHO gas was inducted, the brake thermal efficiency of the engine increased by 11.06%, Carbon monoxide decreased by 15.38%, Unburned hydrocarbon decreased by 18.18%, Carbon dioxide increased by 6.06%, however, the NOX emission increased by 11.19%.

  8. Investigation of Colorless Distributed Combustion (CDC) with Swirl for Gas Turbine Application

    Science.gov (United States)

    Khalil Hasan, Ahmed Essam ElDin

    Colorless Distributed Combustion (CDC) with swirl is investigated for gas turbine engine applications due to its benefits for ultra-low pollutants emission, improved pattern factor and thermal field uniformity, low noise emission, and stable combustion with the alleviation of combustion instabilities. Adequate and fast mixing between the injected air and internally recirculated hot reactive gases to form hot and diluted oxidant is critical for CDC, followed by rapid mixing with the fuel. This results in distributed reaction zone instead of a concentrated thin flame front as observed in conventional diffusion flames, leading to avoidance of hot spot regions and providing reduced NOx and CO emissions. The focus of this dissertation is to develop and demonstrate CDC in a cylindrical combustor for application to stationary gas turbine combustors. The dissertation examines the sequential development of ultra-low emission colorless distributed combustor operating at a nominal thermal intensity of 36MW/m3-atm. Initially, the role of swirl is evaluated through comparing the performance of swirling and non-swirling configurations with focus on pollutants emission, stability, and isothermal flowfield through particle image velocimetry. Different fuel injection locations have also been examined, and based on performance a swirling configuration have been down selected for further investigations demonstrating emissions as low as 1 PPM of NO with a 40% reduction compared to non-swirling configuration. Further investigations were performed to outline the impact of inlet air temperature and combustor pressure on reaction distribution and combustor performance. Next, Fuel flexibility has been examined with view to develop CDC combustors that can handle different gaseous and liquid fuels, both traditional and renewable. These fuels included diluted methane, hydrogen enriched methane, propane, ethanol, kerosene, JP-8, Hydrogenated Renewable Jet fuel, and novel biofuel. Swirling CDC

  9. Flexible High Energy Lidar Transmitter for Remote Gas and Wind Sensing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fibertek proposes a high energy and flexible operation 1570 nm pulsed lidar transmitter for airborne and space-based remote CO2 gas and doppler wind sensing. The...

  10. Gas sensing properties of Cu and Cr activated BST thick films

    Indian Academy of Sciences (India)

    G H Jain; L A Patil

    2006-08-01

    H2S gas sensing properties of BST ((Ba0.67Sr0.33)TiO3) thick films are reported here for the first time. BST ceramic powder was prepared by mechanochemical process. Thick films of BST were prepared by screen-printing technique. The sensing performance of the films was tested for various gases. The films were surface customized by dipping them into aqueous solutions of CuCl2 and CrO3 for various intervals of time. These surface modified BST films showed improved sensitivity to H2S gas (100 ppm) than pure BST film. Chromium oxide was observed to be a better activator than copper oxide in H2S gas sensing. The effect of microstructure and amount of activators on H2S gas sensing were discussed. The sensitivity, selectivity, stability, response and recovery time of the sensor were measured and presented.

  11. Hydrothermal synthesis of self-assembled hierarchical tungsten oxides hollow spheres and their gas sensing properties.

    Science.gov (United States)

    Li, Jinwei; Liu, Xin; Cui, Jiashan; Sun, Jianbo

    2015-05-20

    Hierarchical self-assembled hollow spheres (HS) of tungsten oxide nanosheets have been synthesized via a template-free hydrothermal method. Morphology evolution of the products is determined by the amount of H2C2O4 (oxalic acid) which serves as chelating agent. Structural features of the products were characterized by X-ray diffraction (XRD), and morphology was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, the porous structure was analyzed using the Brunauer-Emmett-Teller (BET) approach. The synthesis mechanism of the products with self-assembled hierarchical structures was proposed. The NO2 gas sensing properties of self-assembled hierarchical WO3 HS materials were investigated, the gas sensing properties of WO3 synthesized by a variety of formulations were compared, and the possible gas sensing mechanism was discussed. The obvious enhancement of the gas sensing properties was ascribed to the structure of the hierarchical HS.

  12. Computational Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, C K; Mizobuchi, Y; Poinsot, T J; Smith, P J; Warnatz, J

    2004-08-26

    Progress in the field of computational combustion over the past 50 years is reviewed. Particular attention is given to those classes of models that are common to most system modeling efforts, including fluid dynamics, chemical kinetics, liquid sprays, and turbulent flame models. The developments in combustion modeling are placed into the time-dependent context of the accompanying exponential growth in computer capabilities and Moore's Law. Superimposed on this steady growth, the occasional sudden advances in modeling capabilities are identified and their impacts are discussed. Integration of submodels into system models for spark ignition, diesel and homogeneous charge, compression ignition engines, surface and catalytic combustion, pulse combustion, and detonations are described. Finally, the current state of combustion modeling is illustrated by descriptions of a very large jet lifted 3D turbulent hydrogen flame with direct numerical simulation and 3D large eddy simulations of practical gas burner combustion devices.

  13. Combustion strategies for a SI direct injection natural gas engine; Darstellung verschiedener Betriebsstrategien an einem Erdgasmotor mit innerer Gemischbildung

    Energy Technology Data Exchange (ETDEWEB)

    Bohatsch, S.; Hoffmann, B.; Ferrari, A.; Chiodi, M.; Berner, H.J.; Bargende, M.

    2006-07-01

    Natural gas as a fuel for internal combustion engines is a combustion technology showing great promise for the reduction of CO{sub 2} and particulate matter. To demonstrate the potential of natural gas direct injection some experimental investigations were carried out using a single-cylinder engine with lateral injector position. For this different injection valve nozzles, piston crown geometries as well as operating strategies were investigated. First experimental results accompanied by additional CFD-simulation show that it is possible to control the burn rate by injection induced turbulence. Furthermore the results show that a short mixture preparation distance between injection nozzle and spark plug is necessary because of the poor fuel penetration during the injection process which is typical for gaseous fuels. (orig.)

  14. Combustion efficiency: Greenhouse gas emission reductions from the power generation sector

    Energy Technology Data Exchange (ETDEWEB)

    Kane, R.; South, D.W.; Fish, A.L. [Argonne National Laboratory, Upton, IL (United States)

    1993-12-31

    Concern for the possibility of an enhanced greenhouse effect and global climate change (GCC) has often been associated with energy use in general, and fossil fuel combustion in particular, because of associated emissions of CO{sub 2} and other greenhouse gases (GHG). Therefore, energy policies play a significant role in determining greenhouse gas emissions. The generation of electricity and power from more efficient fossil energy technologies provides an opportunity to significantly lower GHG emissions, together with other pollutants. The U.S. government oversees a broad-based program to facilitate the development, demonstration, and deployment of these technologies. Advanced fossil technologies offer other benefits as well, in that they permit continued use of widely available fuels such as coal. An international perspective is critical for assessing the role of these fuels, since countries differ in terms of their ability to maximize these benefits. Often, new technologies are considered the domain of industrialized countries. Yet more efficient technologies may have their greatest potential - to concurrently permit the utilization of indigenous fuels and to lower global GHG emissions in developing countries, especially those in the Asia-Pacific region.

  15. Laser diagnostics of combustion phenomena related to engines/gas turbines. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Alden, Marcus [Lund Inst. of Technology (Sweden). Dept. of Combustion

    2000-05-01

    The following project has been a one year project bridging the time between the NUTEK program in 'Motorrelaterad foerbraenning' and the new STEM program in 'Energisystem i vaegfordon. The activities has included three Ph. D students and the project has been directed towards two main areas. The first area is the development and application of a new laser diagnostic technique based on laser-induced fluorescence from atomic species for measurements of two-dimensional temperatures in combustion systems. The technique has shown to have distinct advantages compared to more commonly used laser techniques and it has been applied both in engines (VOLVO PV) as well as in gas turbines (VOLVO Aero Corp.) A major advantage is the potential, recently investigated, to make measurements in sooty environments. The second area is in the area of development and application of a technique for measurements of two-dimensional soot volume fractions and particle sizes. The technique is called Laser-induced Incandescence, LII, and here a laser beam is heating the particle considerably above the flame temperature and by detecting the increased blackbody radiation, the parameters above can be inferred. During the year most work has been to develop the technique, but distinct applications in burners, engines and model fires are planned.

  16. TMF cracking in metallic heat shields of gas turbine combustion chambers

    Energy Technology Data Exchange (ETDEWEB)

    Neidel, Andreas; Cagliyan, Erhan; Jahnke, Anne; Riesenbeck, Susanne; Ullrich, Thomas; Wallich, Sebastian [Siemens Energy Sector, Berlin (Germany). Berlin Gas Turbine Plant

    2012-07-01

    Several metallic heat shields of the combustion chamber of a large industrial gas turbine were affected by thermo-mechanical cracking after long service exposure. The base metal Alloy 617 is coated with a thermal barrier system. While microstructural evidence allowed the exclusion of creep damage as the metallurgical cause of failure, other microstructural features led to the conclusion that the affected components were massively overheated and experienced service temperatures of up to 1100 C. There are several possible reasons for such overheating, ranging from burner failure and lack of cooling to abuse in service. A discussion of these factors is not the subject of this case study. [German] Einzelne metallische Hitzeschildplatten aus der Brennkammer einer grossen Industriegasturbine zeigten nach langer Einsatzdauer Temperaturwechselrisse. Der Grundwerkstoff aus der Nickelbasis- Knetlegierung Alloy 617 traegt zusaetzlich ein Thermobarriere- Schutzschichtsystem. Waehrend der Gefuegebefund eindeutig keine Hinweise auf eine Kriechschaedigung ergab, liessen andere Gefuegemerkmale den Schluss zu, dass die betroffenen Bauteile im Betrieb massiv ueberhitzt wurden und Temperaturen von mindestens 1100 C ausgesetzt waren. Gruende fuer solche Ueberhitzungen koennen vielfaeltig sein und reichen von Brennerversagen ueber Kuehlungsausfall bis zu missbraeuchlichen Betriebszustaenden. Deren Besprechung ist nicht Gegenstand dieser Fallstudie.

  17. Active control of combustion instabilities in low NO{sub x} gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Zinn, B.T.; Neumeier, Y. [Georgia Institute of Technology, Atlanta, GA (United States)

    1995-10-01

    This 3-year research program was initiated in September, 1995, to investigate active control of detrimental combustion instabilities in low NO{sub x} gas turbines (LNGT), which burn natural gas in a lean premixed mode to reduce NO{sub x} emissions. The program will investigate the mechanisms that drive these instabilities. Furthermore, it will study active control systems (ACS) that can effectively prevent the onset of such instabilities and/or reduce their amplitudes to acceptable levels. An understanding of the driving mechanisms will not only guide the development of effective ACS for LNGT but may also lead to combustor design changes (i.e., passive control) that will fully or partially resolve the problem. Initial attempts to stabilize combustors (i.e., chemical rockets) by ACS were reported more than 40 years ago, but were unsuccessful due to lack of adequate sensors, electronics, and actuators for performing the needed control actions. Progress made in recent years in sensor and actuator technology, electronics, and control theory has rekindled interest in developing ACS for unstable combustors. While initial efforts in this area, which focused on active control of instabilities in air breathing combustors, have demonstrated the considerable potential of active control, they have also indicated that more effective observers, controllers, and actuators are needed for practical applications. Considerable progress has been made in the observer and actuator areas by the principal investigators of this program during the past 2 years under an AFOSR program. The developed observer is based upon wavelets theory, and can identify the amplitudes, frequencies, and phases of the five most dominant combustor modes in (virtually) real time. The developed actuator is a fuel injector that uses a novel magneto-strictive material to modulate the fuel flow rate into the combustor.

  18. Enhanced transduction of photonic crystal dye lasers for gas sensing via swelling polymer film

    DEFF Research Database (Denmark)

    Smith, Cameron; Lind, Johan Ulrik; Christiansen, Mads Brøkner;

    2011-01-01

    We present the enhanced transduction of a photonic crystal dye laser for gas sensing via deposition of an additional swelling polymer film. Device operation involves swelling of the polymer film during exposure to specific gases, leading to a change in total effective refractive index. Experimental...... in its application to other intracavity-based detection schemes to enable gas sensing. © 2011 Optical Society of America....

  19. Wireless gas sensing in South African underground platinum mines

    CSIR Research Space (South Africa)

    Abu-Mahfouz, Adnan M

    2014-04-01

    Full Text Available Approximately 70% of South African mines are classified as fiery, where methane gas potentially could cause explosions. The number of flammable gas reports and accidents are increasing steadily for both gold and platinum mines. However...

  20. Gas sensing properties of MWCNT layers electrochemically decorated with Au and Pd nanoparticles.

    Science.gov (United States)

    Dilonardo, Elena; Penza, Michele; Alvisi, Marco; Rossi, Riccardo; Cassano, Gennaro; Di Franco, Cinzia; Palmisano, Francesco; Torsi, Luisa; Cioffi, Nicola

    2017-01-01

    Multiwalled carbon nanotube (MWCNT)-based chemiresistors were electrochemically decorated with Au and Pd nanoparticles (NPs), resulting in an improvement in the detection of gaseous pollutants as compared to sensors based on pristine MWCNTs. Electrophoresis was used to decorate MWCNTs with preformed Au or Pd NPs, thus preserving their nanometer-sized dimensions and allowing the metal content to be tuned by simply varying the deposition time. The sensing response of unmodified and metal-decorated MWCNTs was evaluated towards different gaseous pollutants (e.g., NO2, H2S, NH3 and C4H10) at a wide range of concentrations in the operating temperature range of 45-200 °C. The gas sensing results were related to the presence, type and loading of metal NPs used in the MWCNT functionalization. Compared to pristine MWCNTs, metal-decorated MWCNTs revealed a higher gas sensitivity, a faster response, a better stability, reversibility and repeatability, and a low detection limit, where all of these sensing properties were controlled by the type and loading of the deposited metal catalytic NPs. Specifically, in the NO2 gas sensing experiments, MWCNTs decorated with the lowest Au content revealed the highest sensitivity at 150 °C, while MWCNTs with the highest Pd loading showed the highest sensitivity when operated at 100 °C. Finally, considering the reported gas sensing results, sensing mechanisms have been proposed, correlating the chemical composition and gas sensing responses.

  1. The recovery of waste and off-gas in Large Combustion Plants subject to IPPC National Permit in Italy.

    Science.gov (United States)

    Di Marco, Giuseppe; Manuzzi, Raffaella

    2017-08-14

    The recovery of off-gas, waste, and biomass in Large Combustion Plants for energy production gives the opportunity to recycle waste and by-products and to recover materials produced in agricultural and industrial activities. The paper illustrates the Italian situation regarding the production of energy from off-gas, biomass, and waste in Large Combustion Plants subject to Integrated Pollution Prevention and Control (IPPC) National Permit. Moreover, it focuses on the 4 Italian Large Combustion Plants producing energy from biomass and waste. For these ones it illustrates the specific issues related to and provides a description of the solutions adopted in the 4 Italian plants. Given that air emission performance is the most relevant aspect of this kind of plants, the paper specifically focuses and reports results about this subject. In particular, in Italy among 113 LCPs subject to IPPC National Permit we have found that 4 plants use as fuel waste (i.e. solid or liquid biomasses and Solid Recovered Fuels), or a mixture of waste and traditional fuels (co-combustion of Solid Recovered Fuels and coal), and that 11 plants use as fuel off-gases listed in Annex X (i.e. Refinery Fuel Gas, Syngas, and gases produced in iron and steel industries). Moreover, there are 2 IPPC chemical plants that recovery energy from different off-gases not listed in Annex X. Regarding the 4 LCPs that produce energy from waste combustion or co-combustion, we find that they take into account all the specific issues related to this kind of plants (i.e. detailed waste characterization, waste acceptance procedures, waste handling and storage, waste pretreatment and emissions to air), and adopt solutions that are best available techniques to prevent pollution. Moreover for one of these plants, the only one for which we have a significant set of monitoring data because it obtained the IPPC National Permit in 2008, we find that energy efficiency and air emissions of the principal pollutants are in

  2. Versatile computer-controlled system for characterization of gas sensing materials.

    Science.gov (United States)

    Zhao, M; Huang, J X; Wong, M H; Tang, Y M; Ong, C W

    2011-10-01

    Design of a system used for characterizing gas sensing materials is described. It is distinctive of being able to measure electrical and optical responses of a sample simultaneously, control a number of measurement parameters, perform fast exchange of gaseous environment, and be fully controlled automatically. These features make the system to be versatile in determining most concerned performance indexes of a gas sensing material (e.g., sensitivity, stability, selectivity, response/recovery times, etc.) as functions of various combinations of measurement conditions (e.g., gas concentrations, temperature, total pressure, content of interferants, photo assist, relative humidity, soaking time in a fixed gas concentration, and number of switching cycles in a dynamic test, etc.). Rationales of the designs associated with general gas sensing mechanics are discussed.

  3. Structural properties and gas sensing behavior of sol-gel grown nanostructured zinc oxide

    Science.gov (United States)

    Rajyaguru, Bhargav; Gadani, Keval; Rathod, K. N.; Solanki, Sapana; Kansara, S. B.; Pandya, D. D.; Shah, N. A.; Solanki, P. S.

    2016-05-01

    In this communication, we report the results of the studies on structural properties and gas sensing behavior of nanostructured ZnO grown using acetone precursor based modified sol-gel technique. Final product of ZnO was sintered at different temperatures to vary the crystallite size while their structural properties have been studied using X-ray diffraction (XRD) measurement performed at room temperature. XRD results suggest the single phasic nature of all the samples and crystallite size increases from 11.53 to 20.96nm with increase in sintering temperature. Gas sensing behavior has been studied for acetone gas which indicates that lower sintered samples are more capable to sense the acetone gas and related mechanism has been discussed in the light of crystallite size, crystal boundary density, defect mechanism and possible chemical reaction between gas traces and various oxygen species.

  4. Ultrathin Gas Permeable Oxide Membranes for Chemical Sensing: Nanoporous Ta2O5 Test Study

    Directory of Open Access Journals (Sweden)

    Alexander Imbault

    2015-09-01

    Full Text Available Conductometric gas sensors made of gas permeable metal oxide ultrathin membranes can combine the functions of a selective filter, preconcentrator, and sensing element and thus can be particularly promising for the active sampling of diluted analytes. Here we report a case study of the electron transport and gas sensing properties of such a membrane made of nanoporous Ta2O5. These membranes demonstrated a noticeable chemical sensitivity toward ammonia, ethanol, and acetone at high temperatures above 400 °C. Different from traditional thin films, such gas permeable, ultrathin gas sensing elements can be made suspended enabling advanced architectures of ultrasensitive analytical systems operating at high temperatures and in harsh environments.

  5. Real-Time Study of Noxious Gas Emissions and Combustion Efficiency of Blended Mixtures of Neem Biodiesel and Petrodiesel

    Directory of Open Access Journals (Sweden)

    Mohammed Khan

    2013-05-01

    Full Text Available Neem biodiesel is currently being explored as a future biofuel and was extracted chemically from the vegetable oil. Many of its properties are still under investigation and our aim was to study its noxious-gas emission profiles from blends with regular petroleum diesel. The distinct advantage of a real-time study is acquisition of in situ data on the combustion behavior of gas components with actual progression of time. Mixtures of neem biodiesel and petroleum diesel corresponding to neem additives of 5%, 10%, 15% and 25% were tested for combustion efficiency and emitted gases using a high-performance gas analyzer. Our study, therefore, investigated the overall efficiency of the combustion process linked to emissions of the following gases: O2, CO2, NO, NOx and SO2. The results for the 95/5% blend compared to the neat sample were most promising and showed no serious change in performance efficiency (<2%. NO/NOx emission trends displayed maxima/minima, suggestive of interconvertible chemical reactivity. Declining CO and SO2 emissions were consistent with rapid chemical conversion. The CO and SO2 concentrations fell well below the toxic atmospheric limits in less than 300 s. The results are generally encouraging for blends below 10%. The potential environmental impact of the study is discussed.

  6. Combustion characteristics of diesel engine using producer gas and blends of Jatropha methyl ester with diesel in mixed fuel mode

    Directory of Open Access Journals (Sweden)

    Hifjur Raheman

    2014-12-01

    Full Text Available An experimental investigation was performed to study the combustion characteristics of diesel engine fuelled with producer gas-biodiesel in dual fuel mode. Three different fuel blends of Jatropha methyl ester with high speed diesel (HSD (B10, B20 and B100 were used with producer gas obtained from the gasification of briquettes made from de-oiled Jatropha seed cake. The increments in load on the engine increased the brake thermal efficiency, exhaust gas temperature and lowered the brake specific energy consumption. The ignition delays in dual-fuel mode of operation for both the fuels were longer than for single-fuel mode of operation. Combustion pressure and heat release rate (HRR patterns at different engine loads were found to be similar for biodiesel and HSD. In dual-fuel mode, the peak pressure and HRR for producer gas–biodiesel dual-fuel were slightly lower than those of producer gas–diesel combustion at full load condition. Significantly lower NOx emissions were obtained under the dual fuel mode of operation for both pilot fuels compared to the single-fuel mode especially HSD under all test conditions.

  7. Optical sensing elements for nitrogen dioxide (NO.sub.2) gas detection, a sol-gel method for making the sensing elements and fiber optic sensors incorporating nitrogen dioxide gas optical sensing elements

    Science.gov (United States)

    Mechery, Shelly John; Singh, Jagdish P.

    2007-07-03

    A sensing element, a method of making a sensing element, and a fiber optic sensor incorporating the sensing element are described. The sensor can be used for the quantitative detection of NO.sub.2 in a mixture of gases. The sensing element can be made by incorporating a diazotizing reagent which reacts with nitrous ions to produce a diazo compound and a coupling reagent which couples with the diazo compound to produce an azo dye into a sol and allowing the sol to form an optically transparent gel. The sensing element changes color in the presence of NO.sub.2 gas. The temporal response of the absorption spectrum at various NO.sub.2 concentrations has also been recorded and analyzed. Sensors having different design configurations are described. The sensing element can detect NO.sub.2 gas at levels of parts per billion.

  8. Next Generation Pressurized Oxy-Coal Combustion: High Efficiency and No Flue Gas Recirculation

    Energy Technology Data Exchange (ETDEWEB)

    Rue, David

    2013-09-30

    The Gas Technology Institute (GTI) has developed a pressurized oxy-coal fired molten bed boiler (MBB) concept, in which coal and oxygen are fired directly into a bed of molten coal slag through burners located on the bottom of the boiler and fired upward. Circulation of heat by the molten slag eliminates the need for a flue gas recirculation loop and provides excellent heat transfer to steam tubes in the boiler walls. Advantages of the MBB technology over other boilers include higher efficiency (from eliminating flue gas recirculation), a smaller and less expensive boiler, modular design leading to direct scalability, decreased fines carryover and handling costs, smaller exhaust duct size, and smaller emissions control equipment sizes. The objective of this project was to conduct techno-economic analyses and an engineering design of the MBB project and to support this work with thermodynamic analyses and oxy-coal burner testing. Techno-economic analyses of GTI’s pressurized oxy-coal fired MBB technology found that the overall plant with compressed CO2 has an efficiency of 31.6%. This is a significant increase over calculated 29.2% efficiency of first generation oxy-coal plants. Cost of electricity (COE) for the pressurized MBB supercritical steam power plant with CO2 capture and compression was calculated to be 134% of the COE for an air-coal supercritical steam power plant with no CO2 capture. This compares positively with a calculated COE for first generation oxy-coal supercritical steam power plants with CO2 capture and compression of 164%. The COE for the MBB power plant is found to meet the U.S. Department of Energy (DOE) target of 135%, before any plant optimization. The MBB power plant was also determined to be simpler than other oxy-coal power plants with a 17% lower capital cost. No other known combustion technology can produce higher efficiencies or lower COE when CO2 capture and compression are included. A thermodynamic enthalpy and exergy analysis

  9. Hydrogen gas sensing feature of polyaniline/titania (rutile) nanocomposite at environmental conditions

    Energy Technology Data Exchange (ETDEWEB)

    Milani Moghaddam, Hossain, E-mail: hossainmilani@yahoo.com [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Nasirian, Shahruz [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Basic Sciences Department, Mazandaran University of Science and Technology, Babol (Iran, Islamic Republic of)

    2014-10-30

    Graphical abstract: - Highlights: • Polyaniline/titania (rutile) nanocomposite (TPNC) was synthesized by a chemical oxidative polymerization method. • Surface morphology and titania (rutile) wt% in TPNC sensors were significant factors for H{sub 2} gas sensing. • TPNC sensors could be used for H{sub 2} gas sensing at different R.H. humidity. • TPNC Sensors exhibited considerable sensitive, reversible and repeatable response to H{sub 2} gas at environmental conditions. - Abstract: The resistance-based sensors of polyaniline/titania (rutile) nanocomposite (TPNC) were prepared by spin coating technique onto an epoxy glass substrate with Cu-interdigited electrodes to study their hydrogen (H{sub 2}) gas sensing features. Our findings are that the change of the surface morphology, porosity and wt% of titania in TPNCs have a significant effect on H{sub 2} gas sensing of sensors. All of the sensors had a reproducibility response toward 0.8 vol% H{sub 2} gas at room temperature, air pressure and 50% relative humidity. A sensor with 40 wt% of titania nanoparticles had better response/recovery time and the response than other sensors. Moreover, H{sub 2} gas sensing mechanism of TPNC sensors based contact areas and the correlation of energy levels between PANI chains and the titania grains were studied.

  10. Characteristics of natural gas lean combustion through the compression of quiescent charge in a rapid compression combustor; Kyusoku asshuku nensho sochinai seishi yokongoki asshuku ni okeru tennen gas no kihaku nensho tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, K. [Okayama University of Science, Okayama (Japan); Segawa, D.; Kadota, T.; Hirooka, S. [University of Osaka Prefecture, Osaka (Japan). Faculty of Engineering; Higashino, K. [Osaka Gas Co. Ltd., Osaka (Japan)

    1997-04-25

    In order to develop a natural gas fueled spark ignition engine with high thermal efficiency and clean exhaust gases, combustion characteristics of natural gas and air mixtures were examined using a rapid compression combustor. We concentrated on lean mixtures because of their potential for high efficiency and low pollutant emissions. To elucidate the effect of compression-induced physical aspects on the combustion process, the charge was kept quiescent before the start of the compression process. The results showed that an increased charge pressure increased the time required for combustion. A high compression ratio or piston speed tended to shorten the combustion time, but their effects were rather weak. An increased humidity in mixtures measurably increased the combustion time. The stratified charge, which was examined using the soap bubble method, markedly improved the combustion process of lean mixtures. 7 refs., 15 figs., 1 tab.

  11. Hot gas cleanup test facility for gasification and pressurized combustion. Quarterly technical progress report, January 1--March 31, 1992

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-01

    This quarterly technical progress report summarizes work completed during the Sixth Quarter of the First Budget Period, January 1 through March 31, 1992, under the Department of Energy (DOE) Cooperative Agreement No. DE-FC21-90MC25140 entitled ``Hot Gas Cleanup Test Facility for Gasification and Pressurized Combustion.`` The objective of this project is to evaluate hot gas particle control technologies using coal-derived gas streams. The major emphasis during this reporting period was expanding the test facility to address system integration issues of hot particulate removal in advanced power generation systems. The conceptual design of the facility was extended to include additional modules for the expansion of the test facility, which is referred to as the Power Systems Development Facility (PSOF). A letter agreement was negotiated between Southern Company Services (SCS) and Foster Wheeler (FW) for the conceptual design of the Advanced Pressurized Fluid-Bed Combustion (APFBC)/Topping Combustor/Gas Turbine System to be added to the facility. The expanded conceptual design also included modifications to the existing conceptual design for the Hot Gas Cleanup Test Facility (HGCTF), facility layout and balance of plant design for the PSOF. Southern Research Institute (SRI) began investigating the sampling requirements for the expanded facility and assisted SCS in contacting Particulate Control Device (PCD) vendors for additional information. SCS also contacted the Electric Power Research Institute (EPRI) and two molten carbonate fuel cell vendors for input on the fuel cell module for the PSDF.

  12. Robust Multivariable Feedback Control of Natural Gas-Diesel RCCI Combustion

    NARCIS (Netherlands)

    Indrajuana, A.; Bekdemir, C.; Luo, X.; Willems, F.P.T.

    2016-01-01

    Advanced combustion concepts such as Reactivity Controlled Compression Ignition (RCCI) demonstrate very high thermal efficiencies combined with ultra low NOx emissions. As RCCI is sensitive for operating conditions, closed-loop control is a crucial enabler for stable and robust combustion. The

  13. Robust Multivariable Feedback Control of Natural Gas-Diesel RCCI Combustion

    NARCIS (Netherlands)

    Indrajuana, A.; Bekdemir, C.; Luo, X.; Willems, F.P.T.

    2016-01-01

    Advanced combustion concepts such as Reactivity Controlled Compression Ignition (RCCI) demonstrate very high thermal efficiencies combined with ultra low NOx emissions. As RCCI is sensitive for operating conditions, closed-loop control is a crucial enabler for stable and robust combustion. The feedb

  14. Thin SnOx films for surface plasmon resonance enhanced ellipsometric gas sensing (SPREE).

    Science.gov (United States)

    Fischer, Daniel; Hertwig, Andreas; Beck, Uwe; Lohse, Volkmar; Negendank, Detlef; Kormunda, Martin; Esser, Norbert

    2017-01-01

    Background: Gas sensors are very important in several fields like gas monitoring, safety and environmental applications. In this approach, a new gas sensing concept is investigated which combines the powerful adsorption probability of metal oxide conductive sensors (MOS) with an optical ellipsometric readout. This concept shows promising results to solve the problems of cross sensitivity of the MOS concept. Results: Undoped tin oxide (SnOx) and iron doped tin oxide (Fe:SnOx) thin add-on films were prepared by magnetron sputtering on the top of the actual surface plasmon resonance (SPR) sensing gold layer. The films were tested for their sensitivity to several gas species in the surface plasmon resonance enhanced (SPREE) gas measurement. It was found that the undoped tin oxide (SnOx) shows higher sensitivities to propane (C3H8) then to carbon monoxide (CO). By using Fe:SnOx, this relation is inverted. This behavior was explained by a change of the amount of binding sites for CO in the layer due to this iron doping. For hydrogen (H2) no such relation was found but the sensing ability was identical for both layer materials. This observation was related to a different sensing mechanism for H2 which is driven by the diffusion into the layer instead of adsorption on the surface. Conclusion: The gas sensing selectivity can be enhanced by tuning the properties of the thin film overcoating. A relation of the binding sites in the doped and undoped SnOx films and the gas sensing abilities for CO and C3H8 was found. This could open the path for optimized gas sensing devices with different coated SPREE sensors.

  15. Examination of charge transfer in Au/YSZ for high-temperature optical gas sensing

    Energy Technology Data Exchange (ETDEWEB)

    Baltrus, John P. [U.S. DOE; Ohodnicki, Paul R. [U.S. DOE

    2014-01-01

    Au-nanoparticle incorporated oxide thin film materials demonstrate significant promise as functionalsensor materials for high temperature optical gas sensing in severe environments relevant for fossil andnuclear based power generation. The Au/yttria-stabilized zirconia (YSZ) system has been extensivelystudied in the literature and serves as a model system for fundamental investigations that seek to betterunderstand the mechanistic origin of the plasmonic gas sensing response. In this work, X-ray photoelec-tron spectroscopy techniques are applied to Au/YSZ films in an attempt to provide further experimentalevidence for a proposed sensing mechanism involving a change in free carrier density of Au nanoparticles due to charge transfer.

  16. DEVELOPMENT OF FINE PARTICULATE EMISSION FACTORS AND SPECIATION PROFILES FOR OIL AND GAS-FIRED COMBUSTION SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Glenn C. England; Stephanie Wien; Mingchih O. Chang

    2002-08-01

    This report provides results from the first year of this three-year project to develop dilution measurement technology for characterizing PM2.5 (particles with aerodynamic diameter smaller than 2.5 micrometers) and precursor emissions from stationary combustion sources used in oil, gas and power generation operations. Detailed emission rate and chemical speciation test results for a refinery gas-fired process heater and plans for cogeneration gas turbine tests and pilot-scale tests are presented. Tests were performed using a research dilution sampling apparatus and traditional EPA methods to compare PM2.5 mass and chemical speciation. Test plans are presented for a gas turbine facility that will be tested in the fourth quarter of 2002. A preliminary approach for pilot-scale tests is presented that will help define design constraints for a new dilution sampler design that is smaller, lighter, and less costly to use.

  17. Interactions Between Surface Reactions and Gas-phase Reactions in Catalytic Combustion and Their Influence on Ignition of HCCI Engine

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The catalytic combustion of methane in a microchannel whose surface was coated with platinum(Pt)catalyst was studied by numerical-simulation. The effects of gas-phase reactions on the whole catalytic combustion process were analyzed at a high inlet pressure. A sensitivity analysis of the detailed mechanisms of the surface reaction of methane on Pt revealed that the most sensitive reactions affecting the heterogeneous ignition are oxygen adsorption/desorption and methane adsorption, and the most sensitive reactions affecting the homogeneous ignition are OH and H2O adsorption/desorption. The combustion process of the homogeneous charge compression ignition(HCCI) engine whose piston face was coated with Pt catalyst was simulated. The effects of catalysis and the most sensitive reactions on the ignition timing and the concentration of the main intermediate species during the HCCI engine combustion are discussed. The results show that the ignition timing of the HCCI engine can be increased by catalysis, and the most sensitive reactions affecting the ignition timing of the HCCI engine are OH and H2O adsorption/desorption.

  18. Quantum dots as mediators in gas sensing: A case study of CdS sensitized WO3 sensing composites

    Science.gov (United States)

    Concina, Isabella; Comini, Elisabetta; Kaciulis, Saulius; Sberveglieri, Giorgio

    2014-01-01

    In this study the proof of principle of the use of naked semiconductor directly generated on metal oxide surface as mediators in gas sensing is provided. Successive ionic layer absorption and reaction (SILAR) technique has been applied to sensitize a WO3 thin film with CdS quantum dots. Response to gases of bare WO3 is deeply modified: quantum dots dramatically increase the metal oxide conductance, otherwise rather poor, and modify the capability of detecting environmental pollutants, such as CO and NO2. A modified sensing mechanism is proposed to rationalize the mediation exerted by the semiconducting active layer on the interaction between gaseous species and WO3 surface.

  19. Room Temperature Ammonia Gas Sensing Characteristics of Co3O4

    Directory of Open Access Journals (Sweden)

    P.N. Shelke

    2011-01-01

    Full Text Available Room temperature ammonia gas-sensing characteristics of Co3O4 pellet sensor are reported in this paper. For this purpose, Co3O4 powder is prepared by a route of simple precipitation + heating at 800 °C/2 hr. The as-prepared powder is characterized by using X-ray diffraction and scanning electron microscopy. The ammonia gas-sensing properties of Co3O4 pellets made at various loads of 3, 5, 7 & 9 ton and at constant time = 4 min. are measured using home-built static gas sensing system. The characterization studies revealed that the cobalt oxide particles formed are cubic spinel Co3O4, highly pure and spherical in shape. The particle size distribution is found to be nearly uniform with average particle size ~ 1 µm. The ammonia gas sensing properties of Co3O4 pellet sensor are found to be good. The highest sensitivities – S.F. = 175 and 358 are found at ~ 25 ppm and 250 ppm concentrations of ammonia gas respectively for the Co3O4 pellet sensor made at the load = 3 ton. Further, an admirable repeatability and reversibility in the ammonia gas sensing characteristics are observed for all the Co3O4 pellet sensors. The average response time of 4.0 min. and recovery time of 3.0 min. are obtained for all the Co3O4 pellet sensors.

  20. Determination of the origin of urinary norandrosterone traces by gas chromatography combustion isotope ratio mass spectrometry.

    Science.gov (United States)

    Hebestreit, Moritz; Flenker, Ulrich; Fusshöller, Gregor; Geyer, Hans; Güntner, Ute; Mareck, Ute; Piper, Thomas; Thevis, Mario; Ayotte, Christiane; Schänzer, Wilhelm

    2006-09-01

    On the one hand, 19-norandrosterone (NA) is the most abundant metabolite of the synthetic anabolic steroid 19-nortestosterone and related prohormones. On the other hand, small amounts are biosynthesized by pregnant women and further evidence exists for physiological origin of this compound. The World Anti-Doping Agency (WADA) formerly introduced threshold concentrations of 2 or 5 ng of NA per ml of urine to discriminate 19-nortestosterone abuse from biosynthetic origin. Recent findings showed however, that formation of NA resulting in concentrations in the range of the threshold levels might be due to demethylation of androsterone in urine, and the WADA 2006 Prohibited List has defined NA as endogenous steroid. To elucidate the endogenous or exogenous origin of NA, (13)C/(12)C-analysis is the method of choice since synthetic 19-nortestosterone is derived from C(3)-plants by partial synthesis and shows delta(13)C(VPDB)-values of around -28 per thousand. Endogenous steroids are less depleted in (13)C due to a dietary mixture of C(3)- and C(4)-plants. An extensive cleanup based on two high performance liquid chromatography cleanup steps was applied to quality control and doping control samples, which contained NA in concentrations down to 2 ng per ml of urine. (13)C/(12)C-ratios of NA, androsterone and etiocholanolone were measured by gas chromatography/combustion/isotope ratio mass spectrometry. By comparing delta(13)C(VPDB)-values of androsterone as endogenous reference compound with NA, the origin of NA in doping control samples was determined as either endogenous or exogenous.

  1. An atmospheric pressure high-temperature laminar flow reactor for investigation of combustion and related gas phase reaction systems

    Energy Technology Data Exchange (ETDEWEB)

    Oßwald, Patrick; Köhler, Markus [Institute of Combustion Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, D-70569 Stuttgart (Germany)

    2015-10-15

    A new high-temperature flow reactor experiment utilizing the powerful molecular beam mass spectrometry (MBMS) technique for detailed observation of gas phase kinetics in reacting flows is presented. The reactor design provides a consequent extension of the experimental portfolio of validation experiments for combustion reaction kinetics. Temperatures up to 1800 K are applicable by three individually controlled temperature zones with this atmospheric pressure flow reactor. Detailed speciation data are obtained using the sensitive MBMS technique, providing in situ access to almost all chemical species involved in the combustion process, including highly reactive species such as radicals. Strategies for quantifying the experimental data are presented alongside a careful analysis of the characterization of the experimental boundary conditions to enable precise numeric reproduction of the experimental results. The general capabilities of this new analytical tool for the investigation of reacting flows are demonstrated for a selected range of conditions, fuels, and applications. A detailed dataset for the well-known gaseous fuels, methane and ethylene, is provided and used to verify the experimental approach. Furthermore, application for liquid fuels and fuel components important for technical combustors like gas turbines and engines is demonstrated. Besides the detailed investigation of novel fuels and fuel components, the wide range of operation conditions gives access to extended combustion topics, such as super rich conditions at high temperature important for gasification processes, or the peroxy chemistry governing the low temperature oxidation regime. These demonstrations are accompanied by a first kinetic modeling approach, examining the opportunities for model validation purposes.

  2. Emissions and properties of Bio-oil and Natural Gas Co-combustion in a Pilot Stabilised Swirl Burner

    Science.gov (United States)

    Kowalewski, Dylan

    Fast pyrolysis oil, or bio-oil, has been investigated to replace traditional fossil fuels in industrial burners. However, flame stability is a challenge due to its high water content. In order to address its instability, bio-oil was co-fired with natural gas in a lab scale 10kW swirl burner at energy ratios from 0% bio-oil to 80% bio-oil. To evaluate the combustion, flame shape, exhaust and particulate emissions, temperatures, as well as infrared emission were monitored. As the bio-oil energy fraction increased, NO emissions increased due to the nitrogen content of bio-oil. CO and particulate emissions increased likely due to carbonaceous residue exiting the combustion zone. Unburnt Hydrocarbon (UHC) emissions increased rapidly as combustion became poor at 60-80% bio-oil energy. The temperature and infrared output decreased with more bio-oil energy. The natural gas proved to be effective at anchoring the bio-oil flame to the nozzle, decreasing instances of extinction or blowout.

  3. Numerical and Experimental Investigation of Combustion and Knock in a Dual Fuel Gas/Diesel Compression Ignition Engine

    Directory of Open Access Journals (Sweden)

    A. Gharehghani

    2012-01-01

    Full Text Available Conventional compression ignition engines can easily be converted to a dual fuel mode of operation using natural gas as main fuel and diesel oil injection as pilot to initiate the combustion. At the same time, it is possible to increase the output power by increasing the diesel oil percentage. A detailed performance and combustion characteristic analysis of a heavy duty diesel engine has been studied in dual fuel mode of operation where natural gas is used as the main fuel and diesel oil as pilot. The influence of intake pressure and temperature on knock occurrence and the effects of initial swirl ratio on heat release rate, temperature-pressure and emission levels have been investigated in this study. It is shown that an increase in the initial swirl ratio lengthens the delay period for auto-ignition and extends the combustion period while it reduces NOx. There is an optimum value of the initial swirl ratio for a certain mixture intake temperature and pressure conditions that can achieve high thermal efficiency and low NOx emissions while decreases the tendency to knock. Simultaneous increase of intake pressure and initial swirl ratio could be the solution to power loss and knock in dual fuel engine.

  4. Low NO sub x heavy fuel combustor concept program. Phase 1A: Combustion technology generation coal gas fuels

    Science.gov (United States)

    Sherlock, T. P.

    1982-01-01

    Combustion tests of two scaled burners using actual coal gas from a 25 ton/day fluidized bed coal gasifier are described. The two combustor configurations studied were a ceramic lined, staged rich/lean burner and an integral, all metal multiannual swirl burner (MASB). The tests were conducted over a range of temperature and pressures representative of current industrial combustion turbine inlet conditions. Tests on the rich lean burner were conducted at three levels of product gas heating values: 104, 197 and 254 btu/scf. Corresponding levels of NOx emissions were 5, 20 and 70 ppmv. Nitrogen was added to the fuel in the form of ammonia, and conversion efficiencies of fuel nitrogen to NOx were on the order of 4 percent to 12 percent, which is somewhat lower than the 14 percent to 18 percent conversion efficiency when src-2 liquid fuel was used. The MASB was tested only on medium btu gas (220 to 270 btu/scf), and produced approximately 80 ppmv NOx at rated engine conditions. Both burners operated similarly on actual coal gas and erbs fuel, and all heating values tested can be successfully burned in current machines.

  5. Sulfur Recovery from Acid Gas Using the Claus Process and High Temperature Air Combustion (HiTAC Technology

    Directory of Open Access Journals (Sweden)

    Mohamed Sassi

    2008-01-01

    Full Text Available Sulfur-bearing compounds are very detrimental to the environment and to industrial process equipment. They are often obtained or formed as a by-product of separation and thermal processing of fuels containing sulfur, such as coal, crude oil and natural gas. The two sulfur compounds, which need special attention, are: hydrogen sulfide (H2S and sulfur dioxide (SO2. H2S is a highly corrosive gas with a foul smell. SO2 is a toxic gas responsible for acid rain formation and equipment corrosion. Various methods of reducing pollutants containing sulfur are described in this paper, with a focus on the modified Claus process, enhanced by the use of High Temperature Air Combustion (HiTAC technology in the Claus furnace. The Claus process has been known and used in the industry for over 100 years. It involves thermal oxidation of hydrogen sulfide and its reaction with sulfur dioxide to form sulfur and water vapor. This process is equilibrium-limited and usually achieves efficiencies in the range of 94-97%, which have been regarded as acceptable in the past years. Nowadays strict air pollution regulations regarding hydrogen sulfide and sulfur dioxide emissions call for nearly 100% efficiency, which can only be achieved with process modifications. High temperature air combustion technology or otherwise called flameless (or colorless combustion is proposed here for application in Claus furnaces, especially those employing lean acid gas streams, which cannot be burned without the use of auxiliary fuel or oxygen enrichment under standard conditions. With the use of HiTAC it has been shown, however, that fuel-lean, Low Calorific Value (LCV fuels can be burned with very uniform thermal fields without the need for fuel enrichment or oxygen addition. The uniform temperature distribution favors clean and efficient burning with an additional advantage of significant reduction of NOx, CO and hydrocarbon emission.

  6. 可燃气体报警器原理及其应用研究%Research and Application of Combustible Gas Alarm

    Institute of Scientific and Technical Information of China (English)

    夏一峰; 黄武

    2013-01-01

    可燃气体报警器就是气体泄漏检测报警仪器。如果工业环境中可燃或有毒气体泄漏,当气体报警器检测到气体浓度达到爆炸或中毒报警器设置的临界点时,可燃气体报警器就会发出报警信号,以提醒工作采取安全措施。可燃气体报警器被广泛用于名类化工厂、液化气站、油库等易发生可燃气体泄漏的场所,对这些场所进行实时监测,保障了该类场所的安全工作环境。%Combustible gas alarm is gas leakage detection and alarm instrument. If the combustible industrial environment or poisonous gas leak, when gas alarm detect gas concentration reaches the explosion or poisoning critical point of alarm settings, flammable gas alarm will be issued a warning signal,to remind the work safety measures. Combustible gas alarm is widely used in the name of chemical plant, gas stations, oil depots and other easily combustible gas leakage location, real-time monitoring of these places, the kind of place safe working environment.

  7. Plasma Assisted Ignition and Combustion at Low Initial Gas Temperatures: Development of Kinetic Mechanism

    Science.gov (United States)

    2016-10-05

    Argon (left) and Oxygen (right) atoms from their respec- tive ground states. The proximity of the fluorescence wavelengths ensures a more precise...Varying Repetition Rate and Pulse Width of Nanosecond Discharges on Premixed Lean Methane-Air Combustion Journal of Combustion 2012 137653 [16] Rethmel...International Journal of Flow Control 3 213-32 [17] Takashima K, Adamovich I V, Xiong Zh, Kushner M J, Starikovskaia S M, Czar- netzki U and Luggenhoelscher

  8. Photoluminescent Metal–Organic Frameworks for Gas Sensing

    Science.gov (United States)

    Lin, Rui‐Biao; Liu, Si‐Yang; Ye, Jia‐Wen; Li, Xu‐Yu

    2016-01-01

    Luminescence of porous coordination polymers (PCPs) or metal–organic frameworks (MOFs) is sensitive to the type and concentration of chemical species in the surrounding environment, because these materials combine the advantages of the highly regular porous structures and various luminescence mechanisms, as well as diversified host‐guest interactions. In the past few years, luminescent MOFs have attracted more and more attention for chemical sensing of gas‐phase analytes, including common gases and vapors of solids/liquids. While liquid‐phase and gas‐phase luminescence sensing by MOFs share similar mechanisms such as host‐guest electron and/or energy transfer, exiplex formation, and guest‐perturbing of excited‐state energy level and radiation pathways, via various types of host‐guest interactions, gas‐phase sensing has its unique advantages and challenges, such as easy utilization of encapsulated guest luminophores and difficulty for accurate measurement of the intensity change. This review summarizes recent progresses by using luminescent MOFs as reusable sensing materials for detection of gases and vapors of solids/liquids especially for O2, highlighting various strategies for improving the sensitivity, selectivity, stability, and accuracy, reducing the materials cost, and developing related devices.

  9. Silicon nanowire-based devices for gas-phase sensing

    NARCIS (Netherlands)

    Cao, A.; Sudhölter, E.J.R.; De Smet, L.C.P.M.

    2013-01-01

    Since their introduction in 2001, SiNW-based sensor devices have attracted considerable interest as a general platform for ultra-sensitive, electrical detection of biological and chemical species. Most studies focus on detecting, sensing and monitoring analytes in aqueous solution, but the number of

  10. CORROSION RESISTANCE OF PEARLITIC AND BAINITIC CAST IRON IN A SYNTHETIC SOLUTION OF CONDENSED GAS FROM COMBUSTION

    Directory of Open Access Journals (Sweden)

    Sandra Matos Cordeiro Costa

    2015-03-01

    Full Text Available The corrosion of engine components of the combustion chamber is usually related to the formation of acids such as sulfuric and nitric. These acids are generated by the condensation of combustion gases that usually occur in vehicle exhaust systems. However, with the development of new technologies to reduce emissions, condensation is also being promoted in vehicle combustion chambers. This fact is associated with high exhaust gas recirculation rates, known as EGR (English term for Exhaust Gas Recirculation. Consequently, corrosion problems in the engine components are increasing, especially in cylinder liners alloy manufactured using cast iron. In this study, the corrosion resistance of two cast iron alloys, one with a pearlitic microstructure and the other with a bainite microstructure in a solution simulating the composition of the condensate obtained from the combustion gases. It was found that the microstructure of the cast iron is an important factor affecting the corrosion behavior. The results showed that none of the two materials investigated is resistant to corrosion in the test medium, and the small difference observed between the behavior of the two cast iron was related to its microstructure, which are dependent on their chemical compositions. The cast iron with a pearlitic microstructure showed less formation of corrosion products than the bainitic cast iron. This result is related to the presence of steadite phase, highly stable and resistant to corrosion in pearlitic microstructure. This phase (steadite anchors the corrosion products formed on the surface and act as a partial barrier slowing the progress of the corrosion process, that was more pronounced in the bainitic cast iron.

  11. Determination Of Gas Mixture Components Using Fluctuation Enhanced Sensing And The LS-SVM Regression Algorithm

    Directory of Open Access Journals (Sweden)

    Lentka Łukasz

    2015-09-01

    Full Text Available This paper analyses the effectiveness of determining gas concentrations by using a prototype WO3 resistive gas sensor together with fluctuation enhanced sensing. We have earlier demonstrated that this method can determine the composition of a gas mixture by using only a single sensor. In the present study, we apply Least-Squares Support-Vector-Machine-based (LS-SVM-based nonlinear regression to determine the gas concentration of each constituent in a mixture. We confirmed that the accuracy of the estimated gas concentration could be significantly improved by applying temperature change and ultraviolet irradiation of the WO3 layer. Fluctuation-enhanced sensing allowed us to predict the concentration of both component gases.

  12. Highly Sensitive Capacitive Gas Sensing at Ionic Liquid-Electrode Interfaces.

    Science.gov (United States)

    Wang, Zhe; Guo, Min; Mu, Xiaoyi; Sen, Soumyo; Insley, Thomas; Mason, Andrew J; Král, Petr; Zeng, Xiangqun

    2016-02-01

    We have developed an ultrasensitive gas-detection method based on the measurement of a differential capacitance of electrified ionic liquid (IL) electrode interfaces in the presence and absence of adsorbed gas molecules. The observed change of differential capacitance has a local maximum at a certain potential that is unique for each type of gas, and its amplitude is related to the concentration of the gas molecules. We establish and validate this gas-sensing method by characterizing SO2 detection at ppb levels with less than 1.8% signal from other interfering species (i.e., CO2, O2, NO2, NO, SO2, H2O, H2, and cyclohexane, tested at the same concentration as SO2). This study opens a new avenue of utilizing tunable electrified IL-electrode interfaces for selective sensing of molecules with a kinetic size resolution of 0.1 Å.

  13. Numerical simulation of the combustion in natural gas boiler by using a reduced reaction mechanism; Simulacion numerica de la combustion en una caldera a gas natural utilizando un mecanismo de reaccion reducido

    Energy Technology Data Exchange (ETDEWEB)

    Echaniz, Victoria; Brizuela, Eduardo [Universidad Nacional de Mar del Plata (Argentina). Facultad de Ingenieria. Dept. de Ingenieria Mecanica

    2001-07-01

    Combustion of natural gas in air in a utility boiler is simulated by means of a finite volume approach, using a Reduced Reaction Scheme and Eddy Break Up concepts. Results are presented for a turbulent diffusion flame, under operational conditions and in full size, including heat transfer by conduction/convection and radiation. Preliminary results only are presented and a limited comparison with experimental results is made due to the scope of the task which involves a facility in service. Nevertheless, results are considered satisfactory, although there are indications that it is necessary to continue refining the mixing and radiation models for better matching with operational conditions. (author)

  14. Microwave assisted combustion synthesis of nanocrystalline CoFe{sub 2}O{sub 4} for LPG sensing

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhari, Prashant, E-mail: pchaudhari2007@rediff.com [Datta Meghe Institute of Engg, Tech. & Research, Swangi (M), Wardha, MS. (India); Acharya, S. A., E-mail: saha275@yahoo.com; Darunkar, S. S.; Gaikwad, V. M. [Department of Physics, R.T.M. Nagpur University, Nagpur, MS (India)

    2015-08-28

    A microwave-assisted citrate precursor method has been utilized for synthesis of nanocrystalline powders of CoFe{sub 2}O{sub 4}. The process takes only a few minutes to obtain as-synthesized CoFe{sub 2}O{sub 4}. Structural properties of the synthesized material were investigated by X-ray diffraction; scanning electron microscopy, Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy. The gas sensing properties of thick film of CoFe{sub 2}O{sub 4} prepared by screen printing towards Liquid Petroleum Gas (LPG) revealed that CoFe{sub 2}O{sub 4} thick films are sensitive and shows maximum sensitivity at 350°C for 2500 ppm of LPG.

  15. Effects of Combustion-Induced Vortex Breakdown on Flashback Limits of Syngas-Fueled Gas Turbine Combustors

    Energy Technology Data Exchange (ETDEWEB)

    Ahsan Choudhuri

    2011-03-31

    Turbine combustors of advanced power systems have goals to achieve very low pollutants emissions, fuel variability, and fuel flexibility. Future generation gas turbine combustors should tolerate fuel compositions ranging from natural gas to a broad range of syngas without sacrificing operational advantages and low emission characteristics. Additionally, current designs of advanced turbine combustors use various degrees of swirl and lean premixing for stabilizing flames and controlling high temperature NOx formation zones. However, issues of fuel variability and NOx control through premixing also bring a number of concerns, especially combustor flashback and flame blowout. Flashback is a combustion condition at which the flame propagates upstream against the gas stream into the burner tube. Flashback is a critical issue for premixed combustor designs, because it not only causes serious hardware damages but also increases pollutant emissions. In swirl stabilized lean premixed turbine combustors onset of flashback may occur due to (i) boundary layer flame propagation (critical velocity gradient), (ii) turbulent flame propagation in core flow, (iii) combustion instabilities, and (iv) upstream flame propagation induced by combustion induced vortex breakdown (CIVB). Flashback due to first two foregoing mechanisms is a topic of classical interest and has been studied extensively. Generally, analytical theories and experimental determinations of laminar and turbulent burning velocities model these mechanisms with sufficient precision for design usages. However, the swirling flow complicates the flashback processes in premixed combustions and the first two mechanisms inadequately describe the flashback propensity of most practical combustor designs. The presence of hydrogen in syngas significantly increases the potential for flashback. Due to high laminar burning velocity and low lean flammability limit, hydrogen tends to shift the combustor operating conditions towards

  16. Effects of Combustion-Induced Vortex Breakdown on Flashback Limits of Syngas-Fueled Gas Turbine Combustors

    Energy Technology Data Exchange (ETDEWEB)

    Ahsan Choudhuri

    2011-03-31

    Turbine combustors of advanced power systems have goals to achieve very low pollutants emissions, fuel variability, and fuel flexibility. Future generation gas turbine combustors should tolerate fuel compositions ranging from natural gas to a broad range of syngas without sacrificing operational advantages and low emission characteristics. Additionally, current designs of advanced turbine combustors use various degrees of swirl and lean premixing for stabilizing flames and controlling high temperature NOx formation zones. However, issues of fuel variability and NOx control through premixing also bring a number of concerns, especially combustor flashback and flame blowout. Flashback is a combustion condition at which the flame propagates upstream against the gas stream into the burner tube. Flashback is a critical issue for premixed combustor designs, because it not only causes serious hardware damages but also increases pollutant emissions. In swirl stabilized lean premixed turbine combustors onset of flashback may occur due to (i) boundary layer flame propagation (critical velocity gradient), (ii) turbulent flame propagation in core flow, (iii) combustion instabilities, and (iv) upstream flame propagation induced by combustion induced vortex breakdown (CIVB). Flashback due to first two foregoing mechanisms is a topic of classical interest and has been studied extensively. Generally, analytical theories and experimental determinations of laminar and turbulent burning velocities model these mechanisms with sufficient precision for design usages. However, the swirling flow complicates the flashback processes in premixed combustions and the first two mechanisms inadequately describe the flashback propensity of most practical combustor designs. The presence of hydrogen in syngas significantly increases the potential for flashback. Due to high laminar burning velocity and low lean flammability limit, hydrogen tends to shift the combustor operating conditions towards

  17. Fiber Bragg grating-based wavelength modulation spectroscopy technique for trace gas sensing

    Science.gov (United States)

    Tiwari, Shivani; Vasa, Nilesh J.; Srinivasan, Balaji

    2016-04-01

    A novel gas sensing system based on a tunable fiber Bragg grating (FBG) and a Super luminescent light emitting diode (SLED) source is proposed for trace gas sensing. Such a system has been demonstrated for precise detection of acetylene (C2H2) using wavelength modulation spectroscopy technique (WMS) based on modulating the Bragg wavelength of FBG within the width of an absorption line of a target gas. The sensing system has been calibrated against specific gas concentrations (ppm) through controlled experiments and the minimum detectable acetylene (C2H2) gas concentration is experimentally found to be 80 ppm (0.008% by volume). Furthermore, the detection limit of the system is estimated to be limited by the noise floor of our system at 7 ppm (0.0007% by volume). The proposed system provides a relatively inexpensive alternative for trace gas sensing based on a well-established FBG technology. Moreover, the proposed system has tremendous potential for simultaneous detection of multiple species through the use of a cascaded set of carefully chosen FBGs.

  18. Gas-Tolerant Device Senses Electrical Conductivity of Liquid

    Science.gov (United States)

    O'Connor, Edward W.

    2005-01-01

    The figure depicts a device for measuring the electrical conductivity of a flowing liquid. Unlike prior such devices, this one does not trap gas bubbles entrained in the liquid. Usually, the electrical conductivity of a liquid is measured by use of two electrodes immersed in the liquid. A typical prior device based on this concept contains large cavities that can trap gas. Any gas present between or near the electrodes causes a significant offset in the conductivity reading and, if the gas becomes trapped, then the offset persists. Extensive tests on two-phase (liquid/ gas) flow have shown that in the case of liquid flowing along a section of tubing, gas entrained in the liquid is not trapped in the section as long as the inner wall of the section is smooth and continuous, and the section is the narrowest tubing section along the flow path. The design of the device is based on the foregoing observation: The electrodes and the insulators separating the electrodes constitute adjacent parts of the walls of a tube. The bore of the tube is machined to make the wall smooth and to provide a straight flow path from the inlet to the outlet. The diameter of the electrode/insulator tube assembly is less than the diameter of the inlet or outlet tubing. An outer shell contains the electrodes and insulators and constitutes a leak and pressure barrier. Any gas bubble flowing through this device causes only a momentary conductivity offset that is filtered out by software used to process the conductivity readings.

  19. Phase Noise Squeezing Based Parametric Bifurcation Tracking of MIP-Coated Microbeam MEMS Sensor for TNT Explosive Gas Sensing

    Science.gov (United States)

    2014-06-08

    Based Parametric Bifurcation Tracking of Mip -Coated Microbeam MEMS Sensor for TNT Explosive Gas Sensing See Attached The views, opinions and/or...2050 1 ABSTRACT Phase Noise-Squeezing-Based Parametric Bifurcation Tracking of Mip -Coated Microbeam MEMS Sensor for TNT Explosive Gas Sensing...SQUEEZING BASED PARAMETRIC BIFURCATION TRACKING OF MIP -COATED MICROBEAM MEMS SENSOR FOR TNT EXPLOSIVE GAS SENSING L. L. Li1*, E. L. Holthoff2, L. A

  20. Combined process of pyrolyzer/combuster for gas production and power generation; Chugoku ni okeru chukibo hatsuden to toshi gas seizo no tame no fukugo process no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Ooka, I. [The University of Tokushima, Tokushima (Japan); Ma, T.

    1997-10-30

    In China, they are using a lot of coal by direct firing for domestic cooking, space heating and industrial use. Therefore air pollution is the big problem in every cities in winter season. And at moment, they do not have enough infrastructure for supplying energy such as gas and electric power. There is a great need for facilities for supplying gas and electric power from coal in big cities with much less pollution. This paper d a combined process of medium size plant of gas production and power generation by using fluidized circulation bed pyrolizer and combuster, to contribute to the energy supply which greatly reduces air and water polution and coal consumption. 1 ref., 1 fig., 3 tabs.

  1. Fuel cells: new technology of natural gas for energetical building; Pilas de combustible: nueva tecnologia de gas natural para edificios energeticamente autoabastecidos

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, A. M.

    2000-07-01

    Fuel Cells have emerged in the last decade as one of the most promising new and sustainable natural gas technologies for meeting the energy needs of all the economy sectors into the 21st century. Fuel Cells are an environmentally clean, quiet, and highly efficient method for generating electricity and heat from natural gas. A fuel cell is an electrochemical device that converts the chemical energy of a fuel directly to usable energy (electricity and heat) without combustion. For this reason, the application and use of the fuel cell technology may be the most important technological advancement of the next century. At the beginning of the 2000 year Sociedad de Gas de Euskadi, s. a. started a demonstration project in favour of the high-temperature planar solid oxide fuel cell (SOFC) for domestic micro-CHP utilization. This type is certainly most exacting from the materials standpoint, and it offers the advantage of uncomplicated fuel pretreatment. (Author)

  2. Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing

    Directory of Open Access Journals (Sweden)

    Randy L. Vander Wal

    2009-09-01

    Full Text Available A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. Both nanostructures possess a one-dimensional morphology. Different synthesis methods are used to produce these materials: thermal evaporation-condensation (TEC, controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed. Practical issues associated with harvesting, purification, and integration of these materials into sensing devices are detailed. For comparison to the nascent form, these sensing materials are surface coated with Pd and Pt nanoparticles. Gas sensing tests, with respect to H2, are conducted at ambient and elevated temperatures. Comparative normalized responses and time constants for the catalyst and noncatalyst systems provide a basis for identification of the superior metal-oxide nanostructure and catalyst combination. With temperature-dependent data, Arrhenius analyses are made to determine activation energies for the catalyst-assisted systems.

  3. Hydrodynamique, transfert de chaleur et combustion de gaz naturel en lit fluidisé circulant Hydrodynamics, Heat Transfer and Combustion of Natural Gas in a Circulating Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Feugier A.

    2006-11-01

    Full Text Available L'hydrodynamique, les transferts de chaleur et la combustion du gaz naturel ont été étudiés dans un réacteur à lit circulant de 15 cm de diamètre et de 7 m de haut. Ce réacteur peut opérer avec des vitesses de gaz allant jusqu'à 15 m/s, jusqu'à des températures de 880-900°C et avec des débits de solides compris entre 0 et 15t/h. Les charges utilisées sont des sables de granulométrie allant de 95 à 625 microns. Le profil de concentration en solides dans le réacteur est déterminé à partir du profil de pression. Une corrélation reliant la vitesse de glissement des particules aux principaux paramètres opératoires, rend compte de façon très satisfaisante de l'ensemble des résultats expérimentaux. La mise en place d'un échangeur en paroi dans la partie supérieure du réacteur a permis la détermination de coefficients d'échange thermique. Ces derniers sont essentiellement fonction de la, concentration en particules au droit de l'échangeur et de la granulométrie des particules. Des valeurs allant jusqu'à 200 W/m2 K peuvent, être obtenues. Enfin, la combustion du méthane s'avère très sensible à la présence de particules dans le réacteur. Ces particules ont un effet inhibiteur. Hydrodynamics, heat transfer and combustion of natural gas have been investigated in a circulating-bed reactor 15 cm in diameter and 7 m high. This reactor can operate with gas velocities up to 15 m/s, at temperature up to 880-900°C and with solids flow rates of between 0 and 15 t/h. The solids used are sands with a particle size ranging from 95 to 625 microns. The solids concentration profile in the reactor is determined from the pressure profile. A correlation linking the slippage velocity of particles to the principal operating parameters very satisfactorily takes into consideration the overall experimental results. The installation of a wall heat exchanger in the upper part of the reactor enabled the heat exchange coefficients to be

  4. Study on Influence to Waste Water Treatment Plant’s Sludge by Low-carbon Catalytic Combustion Furnace of Natural Gas

    Directory of Open Access Journals (Sweden)

    Ren TianQi

    2016-01-01

    Full Text Available There are two parts in this experiment. One of is about the concentration of Variation of exhaust gas while heating sludge of waste water treatment plant. The other one is about introduce the problems of the traditional incineration processes of sludge of waste water treatment as compared between the sludge heated by natural gas catalytic combustion furnace and the tradition’s. We can see that natural gas low-carbon catalytic combustion furnace realize the near-zero emission of contaminates.

  5. Synthesis of ZnO nanosheet arrays with exposed (100) facets for gas sensing applications.

    Science.gov (United States)

    Xiao, Chuanhai; Yang, Tianye; Chuai, Mingyan; Xiao, Bingxin; Zhang, Mingzhe

    2016-01-01

    ZnO nanosheet (NS) arrays have been synthesized by a facile ultrathin liquid layer electrodeposition method. The ion concentration and electrode potential play important roles in the formation of ZnO NS arrays. Studies on the structural information indicate that the NSs are exposed with (100) facets. The results of Raman and PL spectra indicate that there existed a large amount of oxygen vacancies in the NSs. The gas sensing performances of the ZnO NS arrays are investigated: the ZnO NS arrays exhibited high gas selectivity and quick response/recovery for detecting NO2 at a low working temperature. High binding energies between NO2 molecules and exposed ZnO(100) facets lead to large surface reconstructions, which is responsible for the intrinsic NO2 sensing properties. In addition, the highly exposed surface and a large amount of oxygen vacancies existing in the NSs also make a great contribution to the gas sensing performance.

  6. Synthesis Methods, Microscopy Characterization and Device Integration of Nanoscale Metal Oxide Semiconductors for Gas Sensing

    OpenAIRE

    Vander Wal, Randy L.; Berger, Gordon M.; Kulis, Michael J.; Hunter, Gary W; Laura Evans; Xu, Jennifer C.

    2009-01-01

    A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. Both nanostructures possess a one-dimensional morphology. Different synthesis methods are used to produce these materials: thermal evaporation-condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed. Practical issues associated with harvesting, purification, and integration of these materials into sensing ...

  7. Photoacoustic trace gas sensing : application to fruit and insects

    NARCIS (Netherlands)

    Persijn, Stefan Timotheüs

    2001-01-01

    A novel photoacoustic spectrometer has been applied to study trace gas emissions by fruit and insects. The spectrometer is based on a newly designed CO laser that can operate on 400 laser lines between 5.1-8.0 and 2.8-4.1 micrometer (delta v=1 and 2 mode, respectively). The spectrometer is equipped

  8. Specular reflection based sensing surface deformation of gas tungsten arc weld pool

    Institute of Scientific and Technical Information of China (English)

    Zhang Shiliang; Gao Jinqiang; Wu Chuansong; Zhang Yuming

    2007-01-01

    A sensing system is developed to measure the weld pool boundary and pool surface deformation in gas tungsten arc welding. LaserStrobe technique is used to eliminate the strong arc light interference, and specular reflection from the pool surface is sensed to describe the relation between the deformed stripes and pool surface depression. Clear images of both the pool boundary and the deformed stripes edges are obtained during gas tungsten arc welding process, which lays foundation for real-time monitoring the pool surface depression and weld penetration.

  9. CFB gasification of biomass residues for co-combustion in large utility boilers studies on ash control and gas cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Kurkela, E.; Moilanen, A.; Nieminen, M. [VTT Energy, Espoo (Finland)

    1999-07-01

    The woody residues of mechanical and chemical wood industry as well as other high-grade woody biofuels can be co-combusted with coal in existing fluidised- bed boilers or even in pulverised combustors without major problems. On the other hand, extensive full-scale test programmes carried out with straw in Denmark and with various agrobiofuels in the United States have clearly shown the limitations of this type of co-combustion methods. Many potential biomass feedstocks, such as straw, have a problematic ash melting behaviour, which causes sintering and fouling problems in combustors. Straw and many fast-growing energy crops as well as industrial and municipal waste fuels often contain high amounts of chlorine and alkali metals, which have a tendency to cause severe corrosion problems in coal-fired boilers. This problem can be assumed to be more severe in the modern plants where supercritical steam values are utilised. Perhaps the most critical factor controlling possibilities for direct co-firing of these problematic biofuels in large PC boilers is the usability of coal ash for cement industry and construction purposes. Demolition wood waste is another example of a locally important renewable feedstock, which is difficult to be introduced into ordinary coal-based combustion plants due to the relatively high content of heavy metals (Zn,Pb, Cd) and chlorine. In principle, there are three main technical solutions to avoid sintering, corrosion and ash problems in co-utilisation of problematic biofuels in large coal-fired power plants: Construction of a smaller separate boiler with low steam values for the biofuels and superheating the steam of the biomass boiler in the coal-fired boiler. Production of pyrolysis oils from the biomass, and Gasification of biomass and combustion of cleaned product gas in the boiler. The concept based on gasification has several advantages over the other alternatives. First of all the gasification reactor, bubbling or circulating fluidised

  10. Effects of injection timing on nonlinear dynamics of the combustion process in the lean-burn premixed natural gas engine

    Science.gov (United States)

    Ding, Shun-Liang; Song, En-Zhe; Yang, Li-Ping; Yao, Chong; Ma, Xiu-Zhen

    2017-02-01

    The nonlinear dynamics of the combustion process in the lean-burn premixed natural gas engine are studied in this paper. Based on nonlinear dynamic theory, the complexity of the combustion process is analyzed under different injection timing conditions. The phase spaces are reconstructed for the experimentally obtained in-cylinder pressure real-time series and the return maps are plotted for the IMEP time series. The results of phase space reconstruction manifest that the attractors are limited to the finite range in the reconstructed phase space. The attractors have a folded and twist geometry structure. The attractors under medium injection timing conditions are looser and more complex. The return maps indicate the coexistence of the stochastic and deterministic components in the patterns combustion process. With the injection timing increasing, there are both a transition from stochastic to deterministic and a transition from deterministic to stochastic, forming the region of deterministic behavior. The largest Lyapunov exponents (LLE) for in-cylinder pressure time series are calculated and the coefficients of variations (COV) of IMEP are also analyzed. The results express that the LLE values are positive. There are a "steep increase" and a "steep decrease" for the LLE and COV values as the injection timing increasing.

  11. Visualization of Gas-to-Liquid (GTL) Fuel Liquid Length and Soot Formation in the Constant Volume Combustion Chamber

    Science.gov (United States)

    Azimov, Ulugbek; Kim, Ki-Seong

    In this research, GTL spray combustion was visualized in an optically accessible quiescent constant-volume combustion chamber. The results were compared with the spray combustion of diesel fuel. Fast-speed photography with direct laser sheet illumination was used to determine the fuel liquid-phase length, and shadowgraph photography was used to determine the distribution of the sooting area in the fuel jet. The results showed that the fuel liquid-phase length of GTL fuel jets stabilized at about 20-22mm from the injector orifice and mainly depended on the ambient gas temperature and fuel volatility. GTL had a slightly shorter liquid length than that of the diesel fuel. This tendency was also maintained when multiple injection strategy was applied. The penetration of the tip of the liquid-phase fuel during pilot injection was a little shorter than the penetration during main injection. The liquid lengths during single and main injections were identical. In the case of soot formation, the results showed that soot formation was mainly affected by air-fuel mixing, and had very weak dependence on fuel volatility.

  12. Fabrication of TiO2 Nanotube Thin Films and Their Gas Sensing Properties

    Directory of Open Access Journals (Sweden)

    Yongxiang Li

    2009-01-01

    Full Text Available The fabrication process and the growth mechanism of titanium/titania nanotubes prepared by anodization process is reviewed, and their applications in the fields of dye sensitized solar cells, photocatalysts, electrochromic devices, gas sensors, and biomaterials are presented. The anodization of Ti thin films on different substrates and the growth process of anodic titanium oxide are described using the current-time curves. Special attention is paid on the influences of the initial film smoothness on the resulted nanoporous morphologies. The “threshold barrier layer thickness model” is used to discuss the growth mechanism. As a case study for gas sensing, anodized highly ordered TiO2 nanotube arrays and nanoporous thin films that show porous surface with an average diameter of 25 nm and interpore distance of 40 nm were prepared. Gas sensors based on such nanotube arrays and nanoporous thin films were fabricated, and their sensing properties were investigated. Excellent H2 gas sensing properties were obtained for sensors prepared from these highly ordered TiO2 nanotube arrays, which present stable response even at a low operating temperature of 90°C. Based on our experimental results, “H-induced O2− desorption” mechanism was used for explaining the hydrogen gas sensing mechanism.

  13. Characteristics of several NIR tuneable diode lasers for spectroscopic based gas sensing: A comparison

    Science.gov (United States)

    Weldon, Vincent; McInerney, David; Phelan, Richard; Lynch, Michael; Donegan, John

    2006-04-01

    Tuneable laser diodes were characterized and compared for use as tuneable sources in gas absorption spectroscopy. Specifically, the characteristics of monolithic widely tuneable single frequency lasers, such as sampled grating distributed Bragg reflector laser and modulated grating Y-branch laser diodes, recently developed for optical communications, with operating wavelengths in the 1520 nm ≤ λ ≤ 1570 nm are compared. The assessment also includes an external cavity laser and a distributed feedback laser for water vapour detection, both emitting at 935 nm. Characteristics investigated include side-mode suppression ratio, ease of tuning, tuning range, spectral emission linewidth, frequency stability and wavelength modulation. While some characteristics differ significantly across the range of lasers, each device has a number of useful intrinsic qualities for gas sensing. Specifically, the modulated grating Y laser and the sampled grating DBR laser have wide quasi-continuous tuneability (30-40 nm) and display relatively low residual amplitude noise when grating-modulated in a harmonic detection scheme. They are particularly suitable for multi-gas sensing. ECLs are also capable of wide quasi-continuous tuneability (100 nm) but their architecture renders them unsuitable for gas sensing application outside a controlled laboratory environment. DFB devices are by far the easiest with which to work but their modest tuneability (4 nm maximum by temperature) almost invariably limits their use to single gas sensing applications.

  14. Metal-core@metal oxide-shell nanomaterials for gas-sensing applications: a review

    Science.gov (United States)

    Mirzaei, A.; Janghorban, K.; Hashemi, B.; Neri, G.

    2015-09-01

    With an ever-increasing number of applications in many advanced fields, gas sensors are becoming indispensable devices in our daily life. Among different types of gas sensors, conductometric metal oxide semiconductor (MOS) gas sensors are found to be the most appealing for advanced applications in the automotive, biomedical, environmental, and safety sectors because of the their high sensitivity, reduced size, and low cost. To improve their sensing characteristics, new metal oxide-based nanostructures have thus been proposed in recent years as sensing materials. In this review, we extensively review gas-sensing properties of core@ shell nanocomposites in which metals as the core and metal oxides as the shell structure, both of nanometer sizes, are assembled into a single metal@metal oxide core-shell. These nanostructures not only combine the properties of both noble metals and metal oxides, but also bring unique synergetic functions in comparison with single-component materials. Up-dated achievements in the synthesis and characterization of metal@metal oxide core-shell nanostructures as well as their use in MOS sensors are here reported with the main objective of providing an overview about their gas-sensing properties.

  15. Temperature Sensing for Oil, Gas, and Structural Analysis

    Science.gov (United States)

    2006-01-01

    In 1996, Systems and Processes Engineering Corporation (SPEC), of Austin, Texas, undertook a NASA Small Business Innovation Research (SBIR) contract with Langley Research Center to develop a compact and lightweight digital thermal sensing (DTS) system for monitoring the cryogenic tanks on the X-33 prototype aircraft. That technology, along with a processor developed by SPEC for Goddard Space Flight Center, was space-qualified and integrated into several NASA missions. SPEC formed an ancillary organization, SensorTran, Inc., to continue work developing the DTS technology for a variety of commercial and industrial applications.

  16. Controls and measurements of KU engine test cells for biodiesel, SynGas, and assisted biodiesel combustion

    Science.gov (United States)

    Cecrle, Eric Daniel

    This thesis is comprised of three unique data acquisition and controls (CDAQ) projects. Each of these projects differs from each other; however, they all include the concept of testing renewable or future fuel sources. The projects were the following: University of Kansas's Feedstock-to-Tailpipe Initiative's Synthesis Gas Reforming rig, Feedstock-to-Tailpipe Initiative's Biodiesel Single Cylinder Test Stand, and a unique Reformate Assisted Biodiesel Combustion architecture. The main responsibility of the author was to implement, develop and test CDAQ systems for the projects. For the Synthesis Gas Reforming rig, this thesis includes a report that summarizes the analysis and solution of building a controls and data acquisition system for this setup. It describes the purpose of the sensors selected along with their placement throughout the system. Moreover, it includes an explanation of the planned data collection system, along with two models describing the reforming process useful for system control. For the Biodiesel Single Cylinder Test Stand, the responsibility was to implement the CDAQ system for data collection. This project comprised a variety of different sensors that are being used collect the combustion characteristics of different biodiesel formulations. This project is currently being used by other graduates in order to complete their projects for subsequent publication. For the Reformate Assisted Biodiesel Combustion architecture, the author developed a reformate injection system to test different hydrogen and carbon monoxide mixtures as combustion augmentation. Hydrogen combustion has certain limiting factors, such as pre-ignition in spark ignition engines and inability to work as a singular fuel in compression ignition engines. To offset these issues, a dual-fuel methodology is utilized by injecting a hydrogen/carbon monoxide mixture into the intake stream of a diesel engine operating on biodiesel. While carbon monoxide does degrade some of the

  17. Controlled Synthesis of Hierarchically Assembled Porous ZnO Microspheres with Enhanced Gas-Sensing Properties

    Directory of Open Access Journals (Sweden)

    Shengsheng You

    2015-01-01

    Full Text Available The ZnO microspheres constructed by porous nanosheets were successfully synthesized by calcinating zinc hydroxide carbonate (ZHC microspheres obtained by a sample hydrothermal method. The samples were characterized in detail with scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, and thermogravimetric and differential scanning calorimetry (TG-DSC. The results indicated that the prepared ZnO microspheres were well crystalline with wurtzite hexagonal phase. The effects of reaction time, temperature, the amount of trisodium citrate, and urea on the morphology of ZnO microspheres were studied. The formation mechanism of porous ZnO microspheres was discussed. Furthermore, the gas-sensing properties for detection of organic gas of the prepared porous ZnO microspheres were investigated. The results indicated that the prepared porous ZnO microspheres exhibited high gas-sensing properties for detection of ethanol gas.

  18. Large-area nanopatterned graphene for ultrasensitive gas sensing

    DEFF Research Database (Denmark)

    Cagliani, Alberto; Mackenzie, David Micheal Angus; Tschammer, Lisa Katharina

    2014-01-01

    Chemical vapor deposited (CVD) graphene is nanopatterned using a spherical block copolymer etch mask. The use of spherical rather than cylindrical block copolymers allows homogeneous patterning of cm-scale areas without any substrate surface treatment. Raman spectroscopy was used to study...... the controlled generation of point defects in the graphene lattice with increasing etching time, confirming that alongside the nanomesh patterning, the nanopatterned CVD graphene presents a high defect density between the mesh holes. The nanopatterned samples showed sensitivities for NO2 of more than one order...... of magnitude higher than for non-patterned graphene. NO2 concentrations as low as 300 ppt were detected with an ultimate detection limit of tens of ppt. This is the smallest value reported so far for non-UV illuminated graphene chemiresistive NO2 gas sensors. The dramatic improvement in the gas sensitivity...

  19. Superior Gas Sensing Properties of Monolayer PtSe2

    KAUST Repository

    Sajjad, Muhammad

    2016-12-15

    First-principles calculations of the structural and electronic properties of monolayer 1T-PtSe2 with adsorbed (a) NO2, (b) NO, (c) NH3, (d) H2O, (e) CO2, and (f) CO molecules are discussed. The results point to great potential of the material in gas sensor applications. Superior sensitivity is demonstrated by transport calculations using the nonequilibrium Green\\'s function method.

  20. Balance térmico de hornos de panaderías con el empleo de gas como combustible

    Directory of Open Access Journals (Sweden)

    Manuel Plá Duporté

    2011-03-01

    Full Text Available En el trabajo se muestra un método para la evaluación térmica de los hornos criollos de panadería, el cual permite calculartodas las pérdidas de calor, la eficiencia y el consumo específico de combustible. Mediante este método se puedenrealizar ajustes de aquellos factores que provocan un incremento en el consumo de combustible de dichos hornos yanalizar las modificaciones y operaciones necesarias para lograr elevar la eficiencia y que sea factible la sustitución delgasoil por gas manufacturado.La evaluación realizada a estos hornos aporta datos hasta ahora desconocidos por ser esta la primera vez que se realizaun estudio usando gas manufacturado; pues en los realizados anteriormente el combustible empleado ha sido diesel.Se llevó a cabo con la ayuda de un programa de computación en Visual Basic y un programa en Excel que permitieron elanálisis de variantes, para la más adecuada valoración técnico económica que permita la toma de decisiones correctas.  In the work an analysis of the feasibility of the substitution of gas-oil for manufactured gas in the net of bakeries of theCity of Havana is made. It is carried out the energy evaluation of a national oven which uses manufactured gas as fuel.This allowed to obtain the different energy losses that take place in the same one, their efficiency and the specificconsumption of energy.This evaluation is carried out for the first time in a national oven using this type of fuel and it was carried out with thehelp of a calculation program in Visual Basic and a program in Excel that allowed the analysis of variants, all thatwith the goal of obtain the appropriate economic technic valuation that allows the taking of correct decisions.

  1. A novel high-heat transfer low-NO{sub x} natural gas combustion system. Phase 1 final report

    Energy Technology Data Exchange (ETDEWEB)

    Rue, D.M. [Institute of Gas Technology, Des Plaines, IL (United States); Fridman, A. [Univ. of Illinois, Chicago (United States); Viskanta, R. [Purdue Univ. (United States); Neff, D. [Cumbustion Tec, Inc. (United States)

    1997-11-01

    Phase I of the project focused on acquiring the market needs, modeling, design, and test plan information for a novel high-heat transfer low-NO{sub x} natural gas combustion system. All goals and objectives were achieved. The key component of the system is an innovative burner technology which combines high temperature natural gas preheating with soot formation and subsequent soot burnout in the flame, increases the system`s energy efficiency and furnace throughput, while minimizing the furnace air emissions, all without external parasitic systems. Work has included identifying industry`s needs and constraints, modeling the high luminosity burner system, designing the prototype burner for initial laboratory-scale testing, defining the test plan, adapting the burner technology to meet the industry`s needs and constraints, and outlining the Industrial Adoption Plan.

  2. Sourcing methane and carbon dioxide emissions from a small city: Influence of natural gas leakage and combustion.

    Science.gov (United States)

    Chamberlain, Samuel D; Ingraffea, Anthony R; Sparks, Jed P

    2016-11-01

    Natural gas leakage and combustion are major sources of methane (CH4) and carbon dioxide (CO2), respectively; however, our understanding of emissions from cities is limited. We mapped distribution pipeline leakage using a mobile CH4 detection system, and continuously monitored atmospheric CO2 and CH4 concentrations and carbon isotopes (δ(13)C-CO2 and δ(13)C-CH4) for one-year above Ithaca, New York. Pipeline leakage rates were low (source in that wind sector. Our results demonstrate pipeline leakage rates are low in cities with a low extent of leak prone pipe, and natural gas power facilities may be an important source of urban and suburban emissions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Design and Development of a TEG Cogenerator Device Integrated into a Self-Standing Natural Combustion Gas Stove

    Science.gov (United States)

    Codecasa, Matteo Paolo; Fanciulli, Carlo; Gaddi, Roberto; Gomez-Paz, Francisco; Passaretti, Francesca

    2015-01-01

    Heating by gas combustion, by use of different types of systems and plants, is widespread in residential and industrial environments. One example is the gas stove, the heat-radiating unit of which operates autonomously with a local gas feed and, possibly, electricity for an optional fan convector. A thermoelectric generator (TEG) can be integrated within this type of autonomous gas heater for local production of electric power, to support electrical auxiliaries, where desired, without the need for any connection to the electricity grid. This approach can lead to easier installation and operation and increases overall efficiency. A new prototype of an autonomous gas heater has been implemented by integration of a TEG device of simple and robust design, easily operated by the end user. A small amount of heat is withdrawn and converted into electricity by the TEG. This enables self-sustaining operation and, moreover, powers new ancillary functions (e.g. fan convector) without extra electrical requirements and no need for an electrical connection.

  4. The catalytic combustion of natural gas in a membrane reactor with separate feed of reactants

    NARCIS (Netherlands)

    Neomagus, H.W.J.P.; Saracco, G.; Wessel, H.F.W.; Versteeg, G.F.

    2000-01-01

    This paper provides an experimental and modelling analysis of the performance of a membrane reactor with separate feed of reactants for the combustion of methane. In this reactor concept methane and air streams are fed at opposite sides of a Pt/γ-Al2O3-activated porous membrane which hosts their

  5. CRYOGENIC TRAPPING OF OXIDIZED MERCURY SPECIES FROM COMBUSTION FLUE GAS. (R827649)

    Science.gov (United States)

    To further understand the speciation and partitioning of mercury species in combustion systems, it is necessary to be able to identify and quantitate the various forms of oxidized mercury. Currently accepted methods for speciating mercury (Ontario Hydro Method, EPA Method 29, ...

  6. Large-Eddy Simulation of Diesel Spray Combustion with Exhaust Gas Recirculation

    Directory of Open Access Journals (Sweden)

    Tillou J.

    2013-11-01

    Full Text Available A Large-Eddy Simulation (LES study of the transient combustion in the spray H experiment investigated in the frame of the Engine Combustion Network (ECN is presented. Combustion is modeled using a LES formulation of the ADF-PCM approach, the principle of which is to tabulate approximated diffusion flames based on the flamelet equation to account for complex chemical effects. The liquid phase is resolved with an Eulerian mesoscopic approach coupled with the DITurBC model for the injection. The structure of the combustion resulting from the n-heptane liquid fuel jet is investigated and compared to the literature. A very good reproduction of experimental findings by the presented LES approach is reported for small EGR rates. Albeit the qualitative effect of increasing the EGR rate is captured, the quantitative quality of the LES predictions deteriorates with increasing EGR rate. One possible explanation for this poor reproduction of EGR effects might be related to the fact that the used semi-detailed scheme was not validated for high EGR rates.

  7. The catalytic combustion of natural gas in a membrane reactor with separate feed of reactants

    NARCIS (Netherlands)

    Neomagus, H.W.J.P.; Saracco, G.; Wessel, H.F.W.; Versteeg, G.F.

    2000-01-01

    This paper provides an experimental and modelling analysis of the performance of a membrane reactor with separate feed of reactants for the combustion of methane. In this reactor concept methane and air streams are fed at opposite sides of a Pt/γ-Al2O3-activated porous membrane which hosts their rea

  8. The catalytic combustion of natural gas in a membrane reactor with separate feed of reactants

    NARCIS (Netherlands)

    Neomagus, H.W.J.P.; Saracco, G.; Wessel, H.F.W.; Versteeg, G.F.

    2000-01-01

    This paper provides an experimental and modelling analysis of the performance of a membrane reactor with separate feed of reactants for the combustion of methane. In this reactor concept methane and air streams are fed at opposite sides of a Pt/γ-Al2O3-activated porous membrane which hosts their rea

  9. Selective Sensing of Gas Mixture via a Temperature Modulation Approach: New Strategy for Potentiometric Gas Sensor Obtaining Satisfactory Discriminating Features

    Science.gov (United States)

    Li, Fu-an; Jin, Han; Wang, Jinxia; Zou, Jie; Jian, Jiawen

    2017-01-01

    A new strategy to discriminate four types of hazardous gases is proposed in this research. Through modulating the operating temperature and the processing response signal with a pattern recognition algorithm, a gas sensor consisting of a single sensing electrode, i.e., ZnO/In2O3 composite, is designed to differentiate NO2, NH3, C3H6, CO within the level of 50–400 ppm. Results indicate that with adding 15 wt.% ZnO to In2O3, the sensor fabricated at 900 °C shows optimal sensing characteristics in detecting all the studied gases. Moreover, with the aid of the principle component analysis (PCA) algorithm, the sensor operating in the temperature modulation mode demonstrates acceptable discrimination features. The satisfactory discrimination features disclose the future that it is possible to differentiate gas mixture efficiently through operating a single electrode sensor at temperature modulation mode. PMID:28287492

  10. Numerical modeling of combustion of low-calorific-producer-gas from Mangium wood within a late mixing porous burner (LMPB

    Directory of Open Access Journals (Sweden)

    Kanokkarn Jirakulsomchok

    2017-08-01

    Full Text Available This article presents a numerical study of combustion of low-calorific-producer-gas from Mangium wood within a late mixing porous burner (LMPB. The LMPB consists of four main components, i.e., the fuel preheating porous (FP, the porous combustor (PC, the air jacket, and the mixing chamber. Interestingly, this LMPB was able to highly preheated and it still maintained high safety in operation. A single-step global reaction, steady state approach and a one-dimensional model were considered. The necessary information for burner characteristics, i.e., temperature profile, flame location and maximum temperature were also presented. The results indicated that stable combustion of a low-calorific-producer-gas within LMPB was possible achieved. Increasing equivalence ratio resulted in increasing in the flame temperature. Meanwhile, increasing the firing rate caused slightly decrease in flame temperature. The flame moved to downstream zone of the PC when the firing rate increased. Finally, it was found that the equivalence ratio did not affect the flame location.

  11. Development of a dynamic simulator for a natural gas combined cycle (NGCC) power plant with post-combustion carbon capture

    Energy Technology Data Exchange (ETDEWEB)

    Liese, E.; Zitney, S.

    2012-01-01

    The AVESTAR Center located at the U.S. Department of Energy’s National Energy Technology Laboratory and West Virginia University is a world-class research and training environment dedicated to using dynamic process simulation as a tool for advancing the safe, efficient and reliable operation of clean energy plants with CO{sub 2} capture. The AVESTAR Center was launched with a high-fidelity dynamic simulator for an Integrated Gasification Combined Cycle (IGCC) power plant with pre-combustion carbon capture. The IGCC dynamic simulator offers full-scope Operator Training Simulator (OTS) Human Machine Interface (HMI) graphics for realistic, real-time control room operation and is integrated with a 3D virtual Immersive Training Simulator (ITS), thus allowing joint control room and field operator training. The IGCC OTS/ITS solution combines a “gasification with CO{sub 2} capture” process simulator with a “combined cycle” power simulator into a single high-performance dynamic simulation framework. This presentation will describe progress on the development of a natural gas combined cycle (NGCC) dynamic simulator based on the syngas-fired combined cycle portion of AVESTAR’s IGCC dynamic simulator. The 574 MW gross NGCC power plant design consisting of two advanced F-class gas turbines, two heat recovery steam generators (HRSGs), and a steam turbine in a multi-shaft 2x2x1 configuration will be reviewed. Plans for integrating a post-combustion carbon capture system will also be discussed.

  12. Gas sensing behaviour of cerium oxide and magnesium aluminate composites

    Indian Academy of Sciences (India)

    N NITHYAVATHY; V RAJENDRAN; L JOHN BERCHMANS; M MAAZA; S KRITHIKA; S ARUNMETHA

    2017-08-01

    Composites of cerium oxide (CeO$_2$) and magnesium aluminate (MgAl$_2$O$_4$) were prepared by the moltensalt synthesis (MSS) method at 1130 K. The composite samples were named as MA, MAC0.07 and MAC0.14 (at CeO$_2$:0, 0.07 and 0.14 g in MgAl$_2$O$_4$, respectively) and these were characterized by X-ray diffraction and energy-dispersiveX-ray analyses. It is seen that the microstructure of the composite samples are quite similar except for a small increasein particle size. The energy-dispersive X-ray analyses provide the presence of concentration of Ce, Mg, Al and O in thecomposite. Scanning electron microscope, coupled with energy-dispersive X-ray analysis (SEM-EDAX) was used to identifythe morphology, microstructure and elemental composition of the prepared samples. The decomposition and dissociationreactions of the precursors were determined using differential thermal and thermogravimetric analysis (TGA). A lone pairof the electron state was identified from the electro paramagnetic resonance spectrum. An optical energy band gap of 3.3 eV was calculated from the UV–Vis absorbance spectra. The gas response to changes in oxygen (O$_2$), carbon monoxide (CO) (at 0.5, 1.0 and 1.5 bar) and ethanol (at 50 and 100 ppm) was quantitatively analysed in all the samples at differentoperating temperatures (300-500 K). The magnitude of the temperature varied linearly regardless of the gas pressure insidethe chamber, by increasing the supply in the heating pad, mounted below the sensor sample. The composite samples indicatea good response to different gases with detection of the smallest change in gas pressure.

  13. El proceso de sustitución de combustibles pesados por gas natural en el sector industrial del Valle del Cauca y del Cauca - Colombia 2004-2012

    Directory of Open Access Journals (Sweden)

    Andrés Eduardo Rangel Jiménez

    2016-01-01

    Full Text Available Este documento tiene por objetivo analizar el proceso de sustitución de la utilización de combustibles pesados hacia el gas natural por parte de medianas y grandes empresas ubicadas en el Valle del Cauca y norte del Cauca, que se observan durante el periodo 2004-2012. Asimismo, utilizando un modelo Probit de efectos aleatorios en Panel, se estima la propensión de estas industrias a sustituir un combustible altamente contaminante por gas natural. Los resultados muestran que la diferencia de gasto en gas con relación a otros combustibles es determinante en la probabilidad de conversión. Adicionalmente, se confirma que las industrias con menos probabilidad de realizar la conversión son aquellas que utilizan carbón en los procesos de producción.

  14. HART手操器在可燃气体探测器检验方面的应用%Application of HART Communicator in Combustible Gas Detector Test

    Institute of Scientific and Technical Information of China (English)

    高佩旺; 刘志刚

    2012-01-01

    The composition of HART communication protocol, combustible gas detector works and HART communicator in the combustible gas detector calibration application were introdued. Convenient and practical was the character of HART communicator calibration combustible gas detector, and it wouldl be widely used with the development of HART.%简要介绍了HART通信协议的构成、可燃气体探测器的工作原理及HART手操器在可燃气体探测器校验中的应用。认为HART手操器校验可燃气体探测器方便、实用,随着HART可燃气体探测器的发展具有很好的应用前景。

  15. Ammonia Gas Sensing Behavior of Tanninsulfonic Acid Doped Polyaniline-TiO2 Composite

    Directory of Open Access Journals (Sweden)

    Venu Gopal Bairi

    2015-10-01

    Full Text Available A highly active tannin doped polyaniline-TiO2 composite ammonia gas sensor was developed and the mechanism behind the gas sensing activity was reported for the first time. A tanninsulfonic acid doped polyaniline (TANIPANI-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticles. X-ray diffraction and thermogravimetric analysis were utilized to determine the incorporation of TiO2 in TANIPANI matrix. UV-Visible and infrared spectroscopy studies provided information about the electronic interactions among tannin, polyaniline, and TiO2. Scanning electron microscopy (SEM along with energy dispersive X-ray spectroscopy (EDS and atomic force microscopy (AFM surface analysis techniques were used to investigate the metal oxide dispersions inside polyaniline matrix. Gas sensors were prepared by spin coating solutions of TANIPANI-TiO2 and TANIPANI composites onto glass slides. Sensors were tested at three different concentrations (20 ppm, 40 ppm, and 60 ppm of ammonia gas at ambient temperature conditions by measuring the changes in surface resistivity of the films with respect to time. Ammonia gas sensing plots are presented showing the response values, response times and recovery times. The TANIPANI-TiO2 composite exhibited better response and shorter recovery times when compared to TANIPANI control and other polyaniline composites that have been reported in the literature. For the first time a proposed mechanism of gas sensing basing on the polaron band localization and its effects on the gas sensing behavior of polyaniline are reported.

  16. Photoluminescence and hydrogen gas-sensing properties of titanium dioxide nanostructures synthesized by hydrothermal treatments

    CSIR Research Space (South Africa)

    Sikhwivhilu, LM

    2012-03-01

    Full Text Available -1 ACS Appl. Mater. Interfaces 2012, 4, 1656-1665 dx.doi.org/10.1021/am2018089 Photoluminescence and Hydrogen Gas-Sensing Properties of Titanium Dioxide Nanostructures Synthesized by Hydrothermal Treatments Lucky M. Sikhwivhilu, Siyasanga Mpelane...

  17. Tungsten sulfide nanoflakes. Synthesis by electrospinning and their gas sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ke; Qin, Xiang; Deng, Da-Shen; Feng, Xu; Zhang, Chao [Chongqing Univ. of Technology, Chongqing (China). Dept. of Physics and Energy; Feng, Wen-Lin [Chongqing Univ. of Technology, Chongqing (China). Dept. of Physics and Energy; Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument, Chongqing (China).

    2017-07-01

    Tungsten sulfide (WS{sub 2}) nanoflakes were successfully prepared via electrospinning with polyvinylpyrrolidone (PVP) as organic solvent. In addition, Ag-deposited WS{sub 2} (Ag-WS{sub 2}) was obtained by chemical blending/calcination method. The structure and morphology of as-prepared materials were characterised by powder X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The XRD result shows that the prepared WS{sub 2} has a graphene-like structure with P{sub 63/mmc} space group symmetry. The SEM illuminates that the sensing samples have nanoflake appearance. Furthermore, heater-type gas sensors were fabricated based on WS{sub 2} and Ag-WS{sub 2} nanomaterials. The sensing responses of WS{sub 2} and Ag-WS{sub 2} on the ammonia (NH{sub 3}), ethanol (C{sub 2}H{sub 5}OH), and acetone (C{sub 3}H{sub 6}O) were investigated at about 220 C. The results indicate that gas sensor based on WS{sub 2} and Ag-WS{sub 2} nanoflakes has 60 ppm sensing threshold value for ammonia. One possible gas sensing mechanism of WS{sub 2} and Ag-WS{sub 2} gas sensors is surface control via charge transfer.

  18. Tungsten Sulfide Nanoflakes: Synthesis by Electrospinning and Their Gas Sensing Properties

    Science.gov (United States)

    Wang, Ke; Feng, Wen-Lin; Qin, Xiang; Deng, Da-Shen; Feng, Xu; Zhang, Chao

    2017-04-01

    Tungsten sulfide (WS2) nanoflakes were successfully prepared via electrospinning with polyvinylpyrrolidone (PVP) as organic solvent. In addition, Ag-deposited WS2 (Ag-WS2) was obtained by chemical blending/calcination method. The structure and morphology of as-prepared materials were characterised by powder X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The XRD result shows that the prepared WS2 has a graphene-like structure with P63/mmc space group symmetry. The SEM illuminates that the sensing samples have nanoflake appearance. Furthermore, heater-type gas sensors were fabricated based on WS2 and Ag-WS2 nanomaterials. The sensing responses of WS2 and Ag-WS2 on the ammonia (NH3), ethanol (C2H5OH), and acetone (C3H6O) were investigated at about 220°C. The results indicate that gas sensor based on WS2 and Ag-WS2 nanoflakes has 60 ppm sensing threshold value for ammonia. One possible gas sensing mechanism of WS2 and Ag-WS2 gas sensors is surface control via charge transfer.

  19. Airborne Shortwave Infrared Spectral Remote Sensing as a Direct Prospecting Method for Oil and Gas Resources

    Institute of Scientific and Technical Information of China (English)

    杨柏林

    1994-01-01

    The spectral characters of hydrocarbons in some oil-bearing strata and soil layers ouer oil and gas reservoirs in the Junggar Basin and northern Tarim Basin in Xinjng are compared with those of chemically pure hydrocarbons.The hydrocarbons are characterized by the bi-absorption at 2310nm and 2350nm.Hydrocarbon and radioactive anomalies in oil and gas terrains are found much more widespread than carbonate alterations.Based on the spectra of heavy hydrocarbons related to oil between 2270nm and 2460nm and refined data treatme nt, remote sensing may hold encouraging promise as a directly prospecting technique for oil and gas resources.

  20. Spectroscopic and electrical sensing mechanism in oxidant-mediated polypyrrole nanofibers/nanoparticles for ammonia gas

    Science.gov (United States)

    Ishpal; Kaur, Amarjeet

    2013-05-01

    Ammonia gas sensing mechanism in oxidant-mediated polypyrrole (PPy) nanofibers/nanoparticles has been studied through spectroscopic and electrical investigations. PPy nanofibers/nanoparticles have been synthesized by chemical oxidation method in the presence of various oxidizing agents such as ammonium persulfate (APS), potassium persulfate (PPS), vanadium pentoxide (V2O5), and iron chloride (FeCl3). Scanning electron microscopy study revealed that PPy nanofibers of about 63, 71 and 79 nm diameters were formed in the presence of APS, PPS, V2O5, respectively, while PPy nanoparticles of about 100-110 nm size were obtained in the presence of FeCl3 as an oxidant. The structural investigations and confirmation of synthesis of PPy were established through Fourier transform infrared and Raman spectroscopy. The gas sensing behavior of the prepared PPy samples is investigated by measuring the electrical resistance in ammonia environment. The observed gas sensing response ( δR R × 100 ) at 100 ppm level of ammonia is 4.5 and 18 % for the samples prepared with oxidizing agents FeCl3 and APS, respectively, and by changing the ammonia level from 50 to 300 ppm, the sensing response varies from 4.5 to 11 % and 10 to 39 %, respectively. Out of all four samples, the PPy nanofibers prepared in the presence of APS have shown the best sensing response. The mechanism of gas sensing response of the PPy samples has been investigated through Raman spectroscopy study. The decrease of charge carrier concentration through reduction of polymeric chains has been recognized through Raman spectroscopic measurements recorded in ammonia environment.

  1. Spectroscopic and electrical sensing mechanism in oxidant-mediated polypyrrole nanofibers/nanoparticles for ammonia gas

    Energy Technology Data Exchange (ETDEWEB)

    Ishpal; Kaur, Amarjeet, E-mail: amarkaur@physics.du.ac.in [University of Delhi, Department of Physics and Astrophysics (India)

    2013-05-15

    Ammonia gas sensing mechanism in oxidant-mediated polypyrrole (PPy) nanofibers/nanoparticles has been studied through spectroscopic and electrical investigations. PPy nanofibers/nanoparticles have been synthesized by chemical oxidation method in the presence of various oxidizing agents such as ammonium persulfate (APS), potassium persulfate (PPS), vanadium pentoxide (V{sub 2}O{sub 5}), and iron chloride (FeCl{sub 3}). Scanning electron microscopy study revealed that PPy nanofibers of about 63, 71 and 79 nm diameters were formed in the presence of APS, PPS, V{sub 2}O{sub 5}, respectively, while PPy nanoparticles of about 100-110 nm size were obtained in the presence of FeCl{sub 3} as an oxidant. The structural investigations and confirmation of synthesis of PPy were established through Fourier transform infrared and Raman spectroscopy. The gas sensing behavior of the prepared PPy samples is investigated by measuring the electrical resistance in ammonia environment. The observed gas sensing response ({Delta}R/Rx100) at 100 ppm level of ammonia is {approx}4.5 and 18 % for the samples prepared with oxidizing agents FeCl{sub 3} and APS, respectively, and by changing the ammonia level from 50 to 300 ppm, the sensing response varies from {approx}4.5 to 11 % and {approx}10 to 39 %, respectively. Out of all four samples, the PPy nanofibers prepared in the presence of APS have shown the best sensing response. The mechanism of gas sensing response of the PPy samples has been investigated through Raman spectroscopy study. The decrease of charge carrier concentration through reduction of polymeric chains has been recognized through Raman spectroscopic measurements recorded in ammonia environment.

  2. Design of waveguide-integrated graphene devices for photonic gas sensing

    Science.gov (United States)

    Cheng, Zhenzhou; Goda, Keisuke

    2016-12-01

    We present waveguide-integrated graphene devices for photonic gas sensing. In a gas environment, graphene’s conductivity is changed by adsorbed gas molecules which serve as charge-carrier donors or acceptors. To accurately probe gas-induced variations in the graphene’s conductivity, we optimize the graphene’s Fermi level and spectral region. Then, we propose graphene-on-silicon and graphene-on-germanium suspended membrane slot waveguides in which propagating light in the waveguide has a strong interaction with the top graphene layer. The gas concentration can be calculated by measuring the spectrum of the optical reflection from the waveguide Bragg grating. The maximum sensitivity of the waveguide-integrated gas sensor can reach one part per million for sensing gaseous nitrogen dioxide. Its sensitivity is about 20 times higher than that of the graphene-covered microfiber sensor and is comparable with that of a graphene plasmonic sensor. The fabrication of the proposed graphene device is CMOS compatible. Our results pave a way for chip-integrated sensitive photonic gas sensors.

  3. Investigating gas sensing mechanism of graphene oxide (GO) thin films through cross-selectivity to various gases

    Science.gov (United States)

    Kumar, Shani; Dhingra, Vishal; Garg, Amit; Chowdhuri, Arijit

    2016-05-01

    Worldwide researchers are actively engaged in utilizing Graphene and its related materials in gas sensing applications. A high surface-to-volume ratio that offers scope of optimization leading to enhanced sensing performance besides lower sensor operating temperatures are some advantages that graphene based sensors possess over conventional semiconducting metal oxide (SMO) sensors. Conventional SMO based gas sensors are known to suffer from problems of cross-selectivity where selectivity is understood to be a gas sensor's ability to preferentially detect one particular gas without responding to or experiencing interference from other gases present in the ambient. In the current study gas sensing mechanism of Graphene oxide (GO) thin films is investigated by repeatedly exposing the sensing configuration to various gases and its cross-selectivity response to the same is examined. In the investigation typical gas sensing response characteristics of the sensor configuration are studied in both oxidizing as well as reducing environments. The gas sensing data is acquired by means of Keithley 6487 picoammeter which is interfaced with a customized Gas Sensing Test Rig (GSTR) that provides a controlled ambient to the sensors for measurement of reproducible characteristics. GSTR further provided the option of varying the operating temperature and gas concentration for the different sensor configurations under study. XRD studies indicate formation of GO with typical crystallite size of 4.2 nm. UV-Vis investigations reveal a typical band-gap of 4.42 (eV) which is in conformity with those reported in the available literature.1,2

  4. Desempeño y emisiones de un motor de combustión interna con combustible dual Diesel – Gas natural ;Performance and emissions study of an internal combustion engine with dual fuel diesel - natural gas

    Directory of Open Access Journals (Sweden)

    Juan Miguel Mantilla González

    2015-04-01

    Full Text Available Muchos de los problemas reportados para los sistemas duales diesel- gas natural ocurren por mala dosificación del gas. Por esta razón se adaptó un sistema de alimentación dual con inyección electrónica de gas natural a un motor de combustión interna encendido por compresión. Se plantea un diseño experimental controlando el dosado de gas natural.Como resultado se obtiene un análisis comparativo entre los valoresde desempeño y emisiones desde la operación Diesel y Diesel-Gas natural. A partir de este análisis es posible observar que el desempeño del motor no se ve afectado por la operación del motor bajo el esquema Dual Diesel-GN, es decir que el motor funcionando bajo modo dual puede sostener las cargas solicitadas al motor. También se observa que la eficiencia volumétrica mejora bajo todas las condiciones de operación dual y las emisiones son mejores sólo cuando el motor trabaja a altas cargas. Many of the problems reported for dual diesel-natural gas systems occur due to poor gas dosage. For this reason a natural gas electronic injection feeding system was adapted to a compression ignitios internal combustion engine. An experimental design controlling the natural gas dosage is considered. As a result a comparative analysis between performance and emissions from the Diesel-and diesel-Natural Gas operation is obtained. From this analysis it is possible to see that engine performance is not affected by operation of the engine under the dual mode, i.e. the motor running under dual mode can support the loads applied to the engine. It is also observed that the volumetric efficiency improves under all conditions of operation and emissions from the dual mode of operation are better only when working at high engine loads.

  5. A Portable Array-Type Optical Fiber Sensing Instrument for Real-Time Gas Detection

    Directory of Open Access Journals (Sweden)

    San-Shan Hung

    2016-12-01

    Full Text Available A novel optical fiber array-type of sensing instrument with temperature compensation for real-time detection was developed to measure oxygen, carbon dioxide, and ammonia simultaneously. The proposed instrument is multi-sensing array integrated with real-time measurement module for portable applications. The sensing optical fibers were etched and polished before coating to increase sensitivities. The ammonia and temperature sensors were each composed of a dye-coated single-mode fiber with constructing a fiber Bragg grating and a long-period filter grating for detecting light intensity. Both carbon dioxide and oxygen sensing structures use multimode fibers where 1-hydroxy-3,6,8-pyrene trisulfonic acid trisodium salt is coated for carbon dioxide sensing and Tris(2,2′-bipyridyl dichlororuthenium(II hexahydrate and Tris(bipyridineruthenium(II chloride are coated for oxygen sensing. Gas-induced fluorescent light intensity variation was applied to detect gas concentration. The portable gas sensing array was set up by integrating with photo-electronic measurement modules and a human-machine interface to detect gases in real time. The measured data have been processed using piecewise-linear method. The sensitivity of the oxygen sensor were 1.54%/V and 9.62%/V for concentrations less than 1.5% and for concentrations between 1.5% and 6%, respectively. The sensitivity of the carbon dioxide sensor were 8.33%/V and 9.62%/V for concentrations less than 2% and for concentrations between 2% and 5%, respectively. For the ammonia sensor, the sensitivity was 27.78%/V, while ammonia concentration was less than 2%.

  6. A Portable Array-Type Optical Fiber Sensing Instrument for Real-Time Gas Detection.

    Science.gov (United States)

    Hung, San-Shan; Chang, Hsing-Cheng; Chang, I-Nan

    2016-12-08

    A novel optical fiber array-type of sensing instrument with temperature compensation for real-time detection was developed to measure oxygen, carbon dioxide, and ammonia simultaneously. The proposed instrument is multi-sensing array integrated with real-time measurement module for portable applications. The sensing optical fibers were etched and polished before coating to increase sensitivities. The ammonia and temperature sensors were each composed of a dye-coated single-mode fiber with constructing a fiber Bragg grating and a long-period filter grating for detecting light intensity. Both carbon dioxide and oxygen sensing structures use multimode fibers where 1-hydroxy-3,6,8-pyrene trisulfonic acid trisodium salt is coated for carbon dioxide sensing and Tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate and Tris(bipyridine)ruthenium(II) chloride are coated for oxygen sensing. Gas-induced fluorescent light intensity variation was applied to detect gas concentration. The portable gas sensing array was set up by integrating with photo-electronic measurement modules and a human-machine interface to detect gases in real time. The measured data have been processed using piecewise-linear method. The sensitivity of the oxygen sensor were 1.54%/V and 9.62%/V for concentrations less than 1.5% and for concentrations between 1.5% and 6%, respectively. The sensitivity of the carbon dioxide sensor were 8.33%/V and 9.62%/V for concentrations less than 2% and for concentrations between 2% and 5%, respectively. For the ammonia sensor, the sensitivity was 27.78%/V, while ammonia concentration was less than 2%.

  7. Preparation of nanostructured PbS thin films as sensing element for NO2 gas

    Science.gov (United States)

    Kaci, S.; Keffous, A.; Hakoum, S.; Trari, M.; Mansri, O.; Menari, H.

    2014-06-01

    In this work, we demonstrate that semiconducting films of AIVBVI compounds, in particular, of nanostructured lead sulfide (PbS) which prepared by chemical bath deposition (CBD), can be used as a sensing element for nitrogen dioxide (NO2) gas. The CBD method is versatile, simple in implementation and gives homogeneous semiconductor structures. We have prepared PbS nanocrystalline thin film at different reaction baths and temperatures. In the course of deposition, variable amounts of additives, such as organic substances among them, were introduced into the baths. The energy dispersive analysis (EDX) confirms the chemical composition of PbS films. A current-voltage (I-V) characterization of Pd/nc-PbS/a-SiC:H pSi(100)/Al Schottky diode structures were studied in the presence of NO2 gas. The gas sensing behavior showed that the synthesized PbS nanocrystalline thin films were influenced by NO2 gas at room temperature. The results can be used for developing an experimental sensing element based on chemically deposited nanostructured PbS films which can be applicable in gas sensors.

  8. Gas/liquid sensing via chemotaxis of Euglena cells confined in an isolated micro-aquarium.

    Science.gov (United States)

    Ozasa, Kazunari; Lee, Jeesoo; Song, Simon; Hara, Masahiko; Maeda, Mizuo

    2013-10-21

    We demonstrate on-chip gas/liquid sensing by using the chemotaxis of live bacteria (Euglena gracilis) confined in an isolated micro-aquarium, and gas/liquid permeation through porous polydimethylsiloxane (PDMS). The sensing chip consisted of one closed micro-aquarium and two separated bypass microchannels along the perimeter of the micro-aquarium. Test gas/liquid and reference samples were introduced into the two individual microchannels separately, and the gas/liquid permeated through the PDMS walls and dissolved in the micro-aquarium water, resulting in a chemical concentration gradient in the micro-aquarium. By employing the closed micro-aquarium isolated from sample flows, we succeeded in measuring the chemotaxis of Euglena for a gas substance quantitatively, which cannot be achieved with the conventional flow-type or hydro-gel-type microfluidic devices. We found positive (negative) chemotaxis for CO2 concentrations below (above) 15%, with 64 ppm as the minimum concentration affecting the cells. We also observed chemotaxis for ethanol and H2O2. By supplying culture medium via the microchannels, the Euglena culture remained alive for more than 2 months. The sensing chip is thus useful for culturing cells and using them for environmental toxicity/nutrition studies by monitoring their motion.

  9. Hydrogen Gas Sensing Characteristics of Nanostructured NiO Thin Films Synthesized by SILAR Method

    Science.gov (United States)

    Karaduman, Irmak; Çorlu, Tugba; Yıldırım, M. Ali; Ateş, Aytunç; Acar, Selim

    2017-03-01

    Nanostructured NiO thin films have been synthesized by a facile, low-cost successive ionic layer adsorption and reaction (SILAR) method, and the effects of the film thickness on their hydrogen gas sensing properties investigated. The samples were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and energy-dispersive x-ray analysis. The XRD results revealed that the crystallinity improved with increasing thickness, exhibiting polycrystalline structure. SEM studies showed that all the films covered the glass substrate well. According to optical absorption measurements, the optical bandgap decreased with increasing film thickness. The gas sensing properties of the nanostructured NiO thin films were studied as a function of operating temperature and gas concentration. The samples showed good sensing performance of H2 gas with high response. The maximum response was 75% at operating temperature of 200°C for hydrogen gas concentration of 40 ppm. These results demonstrate that nanostructured NiO thin films synthesized by the SILAR method have potential for application in hydrogen detection.

  10. 40 CFR 60.107a - Monitoring of emissions and operations for fuel gas combustion devices.

    Science.gov (United States)

    2010-07-01

    ... this section will be considered inherently low in sulfur content. (i) Pilot gas for heaters and flares... content in the fuel gas stream going to the loading rack flare). (2) The effective date of the exemption... monitoring and recording the concentration of reduced sulfur in flare gas. The owner or operator of...

  11. Thermodynamic and transport properties of air and its products of combustion with ASTMA-A-1 fuel and natural gas at 20, 30, and 40 atmospheres

    Science.gov (United States)

    Poferl, D. J.; Svehla, R. A.

    1973-01-01

    The isentropic exponent, molecular weight, viscosity, specific heat at constant pressure, thermal conductivity, Prandtl number, and enthalpy were calculated for air, the combustion products of ASTM-A-1 jet fuel and air, and the combustion products of natural gas and air. The properties were calculated over a temperature range from 300 to 2800 K in 100 K increments and for pressures of 20, 30 and 40 atmospheres. The data for natural gas and ASTM-A-1 were calculated for fuel-air ratios from zero to stoichiometric in 0.01 increments.

  12. A comprehensive evaluation of different radiation models in a gas turbine combustor under conditions of oxy-fuel combustion with dry recycle

    Science.gov (United States)

    Kez, V.; Liu, F.; Consalvi, J. L.; Ströhle, J.; Epple, B.

    2016-03-01

    The oxy-fuel combustion is a promising CO2 capture technology from combustion systems. This process is characterized by much higher CO2 concentrations in the combustion system compared to that of the conventional air-fuel combustion. To accurately predict the enhanced thermal radiation in oxy-fuel combustion, it is essential to take into account the non-gray nature of gas radiation. In this study, radiation heat transfer in a 3D model gas turbine combustor under two test cases at 20 atm total pressure was calculated by various non-gray gas radiation models, including the statistical narrow-band (SNB) model, the statistical narrow-band correlated-k (SNBCK) model, the wide-band correlated-k (WBCK) model, the full spectrum correlated-k (FSCK) model, and several weighted sum of gray gases (WSGG) models. Calculations of SNB, SNBCK, and FSCK were conducted using the updated EM2C SNB model parameters. Results of the SNB model are considered as the benchmark solution to evaluate the accuracy of the other models considered. Results of SNBCK and FSCK are in good agreement with the benchmark solution. The WBCK model is less accurate than SNBCK or FSCK. Considering the three formulations of the WBCK model, the multiple gases formulation is the best choice regarding the accuracy and computational cost. The WSGG model with the parameters of Bordbar et al. (2014) [20] is the most accurate of the three investigated WSGG models. Use of the gray WSSG formulation leads to significant deviations from the benchmark data and should not be applied to predict radiation heat transfer in oxy-fuel combustion systems. A best practice to incorporate the state-of-the-art gas radiation models for high accuracy of radiation heat transfer calculations at minimal increase in computational cost in CFD simulation of oxy-fuel combustion systems for pressure path lengths up to about 10 bar m is suggested.

  13. Studies on the Effects of Interphase Heat Exchange during Thermal Explosion in a Combustible Dusty Gas with General Arrhenius Reaction-Rate Laws

    Directory of Open Access Journals (Sweden)

    K. S. Adegbie

    2012-01-01

    Full Text Available A mathematical model for thermal explosion in a combustible dusty gas containing fuel droplets with general Arrhenius reaction-rate laws, convective and radiative heat losses, and interphase heat exchange between gas and inert solid particles is investigated. The objective of the study is to examine the effects of interphase heat exchange between the gas and solid particles on (i ignition of reacting gas, (ii accumulation of heat by the solid particles during combustion process (iii evaporation of the liquid fuel droplets, and (iv consumption of reacting gas concentration. The equations governing the physical model with realistic assumptions are stated and nondimensionalised leading to an intractable system of first-order coupled nonlinear differential equations, which is not amenable to exact methods of solution. Therefore, we present numerical solutions as well as different qualitative effects of varying interphase heat exchange parameter. Graphs and Table feature prominently to explain the results obtained.

  14. Plasmonic nanopatch array with integrated metal-organic framework for enhanced infrared absorption gas sensing

    Science.gov (United States)

    Chong, Xinyuan; Kim, Ki-joong; Zhang, Yujing; Li, Erwen; Ohodnicki, Paul R.; Chang, Chih-Hung; Wang, Alan X.

    2017-06-01

    In this letter, we present a nanophotonic device consisting of plasmonic nanopatch array (NPA) with integrated metal-organic framework (MOF) for enhanced infrared absorption gas sensing. By designing a gold NPA on a sapphire substrate, we are able to achieve enhanced optical field that spatially overlaps with the MOF layer, which can adsorb carbon dioxide (CO2) with high capacity. Experimental results show that this hybrid plasmonic-MOF device can effectively increase the infrared absorption path of on-chip gas sensors by more than 1100-fold. The demonstration of infrared absorption spectroscopy of CO2 using the hybrid plasmonic-MOF device proves a promising strategy for future on-chip gas sensing with ultra-compact size.

  15. The gas sensing properties of TiO2 nanotubes synthesized by hydrothermal method

    Institute of Scientific and Technical Information of China (English)

    Yan Li Wang; Shun Tan; Jia Wang; Zhi Jin Tan; Qiu Xia Wu; Zheng Jiao; Ming Hong Wu

    2011-01-01

    In this paper, the TiO2 nanotubes were synthesized by hydrothermal method usinga 10 mol/LNaOH aqueous solution at 150 ℃. The structure of prepared materials was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET). The prepared TiO2 nanotubes were used to prepare thick film gas sensors and the gas sensing properties to various gases were tested. Results show the prepared TiO2 nanotube gas sensors responses to ethanol under dry condition at 450 ℃. This could be attributed to the fact that it had high porous morphology and a higher pore volume, which can promote the diffusion of ethanol deep inside the films and improve the sensor response. Moreover, the gas sensor made with nanotubes exhibit high selective response towards ethanol gas compared with H2, CO, acetone.

  16. Gas Sensing Performance of Pure and Modified BST Thick Film Resistor

    Directory of Open Access Journals (Sweden)

    G. H. JAIN

    2008-04-01

    Full Text Available Barium Strontium Titanate (BST-(Ba0.87Sr0.13TiO3 ceramic powder was prepared by mechanochemical process. The thick films of different thicknesses of BST were prepared by screen-printing technique and gas-sensing performance of these films was tested for various gases. The films showed highest response and selectivity to ammonia gas. The pure BST film was surface modified by surfactant CrO3 by using dipping technique. The surface modified film suppresses the response to ammonia and enhances to H2S gas. The surface modification of films changes the adsorption-desorption relationship with the target gas and shifts its selectivity. The gas response, selectivity, response and recovery time of the pure and modified films were measured and presented.

  17. Ceramic Matrix Characterization Under a Gas Turbine Combustion and Loading Environment

    Science.gov (United States)

    2014-03-17

    Ceramics and Ceramic Matrix Composites." Current Opinion in Solid State and Materials Science 5.4 (2001): 301-09. Print. 12. Jacobson , Nathan S...and Nathan S. Jacobson . "SiC Recession Caused by SiO2 Scale Volatility Under Combustion Conditions: II, Thermodynamics and Gaseous-Diffusion Model...10. An Introduction to Thermal Spray. N.d. Instruction Manual. Sulzer Metco Inc., Westbury, NY. 11. Jacobson , N. "Oxidation and Corrosion of

  18. Micro flame-based detector suite for universal gas sensing.

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, Thomas Warren; Washburn, Cody M.; Moorman, Matthew Wallace; Manley, Robert George; Lewis, Patrick Raymond; Miller, James Edward; Clem, Paul Gilbert; Shelmidine, Gregory J.; Manginell, Ronald Paul; Okandan, Murat

    2005-11-01

    A microflame-based detector suit has been developed for sensing of a broad range of chemical analytes. This detector combines calorimetry, flame ionization detection (FID), nitrogen-phosphorous detection (NPD) and flame photometric detection (FPD) modes into one convenient platform based on a microcombustor. The microcombustor consists in a micromachined microhotplate with a catalyst or low-work function material added to its surface. For the NPD mode a low work function material selectively ionizes chemical analytes; for all other modes a supported catalyst such as platinum/alumina is used. The microcombustor design permits rapid, efficient heating of the deposited film at low power. To perform calorimetric detection of analytes, the change in power required to maintain the resistive microhotplate heater at a constant temperature is measured. For FID and NPD modes, electrodes are placed around the microcombustor flame zone and an electrometer circuit measures the production of ions. For FPD, the flame zone is optically interrogated to search for light emission indicative of deexcitation of flame-produced analyte compounds. The calorimetric and FID modes respond generally to all hydrocarbons, while sulfur compounds only alarm in the calorimetric mode, providing speciation. The NPD mode provides 10,000:1 selectivity of nitrogen and phosphorous compounds over hydrocarbons. The FPD can distinguish between sulfur and phosphorous compounds. Importantly all detection modes can be established on one convenient microcombustor platform, in fact the calorimetric, FID and FPD modes can be achieved simultaneously on only one microcombustor. Therefore, it is possible to make a very universal chemical detector array with as little as two microcombustor elements. A demonstration of the performance of the microcombustor in each of the detection modes is provided herein.

  19. Numerical Simulation of NOx Formation in Coal Combustion with Inlet Natural Gas Burning%进口甲烷再燃烧对煤粉燃烧以及Nox生成影响的数值模拟

    Institute of Scientific and Technical Information of China (English)

    张宇; 周力行; 魏小林; 盛宏至

    2005-01-01

    A full two-fluid model of reacting gas-particle flows and coal combustion is used to simulate coal combustion with and without inlet natural gas added in the inlet. The simulation results for the case without natural gas burning is in fair agreement with the experimental results reported in references. The simulation results of different natural gas adding positions indicate that the natural gas burning can form lean oxygen combustion enviroment at the combustor inlet region and the NOx concentration is reduced. The same result can be obtained from chemical equilibrium analysis.

  20. Surface plasmon sensing of gas phase contaminants using optical fiber.

    Energy Technology Data Exchange (ETDEWEB)

    Thornberg, Steven Michael; White, Michael I.; Rumpf, Arthur Norman; Pfeifer, Kent Bryant

    2009-10-01

    Fiber-optic gas phase surface plasmon resonance (SPR) detection of several contaminant gases of interest to state-of-health monitoring in high-consequence sealed systems has been demonstrated. These contaminant gases include H{sub 2}, H{sub 2}S, and moisture using a single-ended optical fiber mode. Data demonstrate that results can be obtained and sensitivity is adequate in a dosimetric mode that allows periodic monitoring of system atmospheres. Modeling studies were performed to direct the design of the sensor probe for optimized dimensions and to allow simultaneous monitoring of several constituents with a single sensor fiber. Testing of the system demonstrates the ability to detect 70mTorr partial pressures of H{sub 2} using this technique and <280 {micro}Torr partial pressures of H{sub 2}S. In addition, a multiple sensor fiber has been demonstrated that allows a single fiber to measure H{sub 2}, H{sub 2}S, and H{sub 2}O without changing the fiber or the analytical system.

  1. Computational fluid dynamics (CFD) analysis of the combustion process of a leather residuals gasification fuel gas: influence of fuel moisture content

    Energy Technology Data Exchange (ETDEWEB)

    Antonietti, Anderson Jose; Beskow, Arthur Bortolin; Silva, Cristiano Vitorino da [Universidade Regional Integrada do Alto Uruguai e das Missoes (URI), Erechim, RS (Brazil)], E-mails: arthur@uricer.edu.br, mlsperb@unisinos.br; Indrusiak, Maria Luiza Sperb [Universidade do Vale do Rio dos Sinos (UNISINOS), Sao Leopoldo, RS (Brazil)], E-mail: cristiano@uricer.edu.br

    2010-07-01

    This work presents a numerical study of the combustion process of leather residuals gasification gas, aiming the improvement of the process efficiency, considering different concentrations of water on the gas. The heating produced in this combustion process can be used to generation of thermal and/or electrical energy, for use at the leather industrial plant. However, the direct burning of this leather-residual-gas into the chambers is not straightforward. The alternative in development consists in processing this leather residuals by gasification or pyrolysis, separating the volatiles and products of incomplete combustion, for after use as fuel in a boiler. At these processes, different quantities of water can be used, resulting at different levels of moisture content in this fuel gas. This humidity can affect significantly the burning of this fuel, producing unburnt gases, as the carbon monoxide, or toxic gases as NOx, which must have their production minimized on the process, with the purpose of reducing the emission of pollutants to the atmosphere. Other environment-harmful-gases, remaining of the chemical treatment employed at leather manufacture, as cyanide, and hydrocarbons as toluene, must burn too, and the moisture content has influence on it. At this way, to increase understanding of the influence of moisture in the combustion process, it was made a numerical investigation study of reacting flow in the furnace, evaluating the temperature field, the chemical species concentration fields, flow mechanics and heat transfer at the process. The commercial CFD code CFX Ansys Inc. was used. Considering different moisture contents in the fuel used on the combustion process, with this study was possible to achieve the most efficient burning operation parameters, with improvement of combustion efficiency, and reduction of environmental harmful gases emissions. It was verified that the different moisture contents in the fuel gas demand different operation conditions

  2. Hexanal Gas Detection Using Chitosan Biopolymer as Sensing Material at Room Temperature

    Directory of Open Access Journals (Sweden)

    Devi Shantini

    2016-01-01

    Full Text Available Hexanal was identified as one of the major volatile gases which are produced in degraded dairy products and wood industries. Therefore, preliminary study on hexanal gas detection with the laboratory scale was carried out in this paper. Electrical testing with chitosan as a sensing material to sense hexanal gas in low concentration was carried out at room temperature. Chitosan sensor was fabricated by using electrochemical deposition technique to form active sensing layer. The response of the chitosan film sensor (CFS towards hexanal was tested via electrical testing by exposing different hexanal concentrations ranging between 20 ppm, 100 ppm, 200 ppm, and 300 ppm using air as a carrier gas. Sensing properties of the CFS toward hexanal exposure including responsibility, recovery, repeatability, stability, and selectively were studied. Overall, our result suggested that hexanal sensor based on chitosan was able to perform well at room temperature demonstrated by good response, good recovery, good repeatability, good stability, and good selectively. This simple and low cost sensor has high potential to be utilized in early quality degradation detection in dairy products and can be used to monitor the level of hexanal exposure in wood industries.

  3. Enhancement of photoresponse and UV-assisted gas sensing with Au decorated ZnO nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Li Yinhua [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0620 (United States); State Key Laboratory of Fine Chemicals, R and D Center of Membrane Science and Technology, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Gong Jian [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0620 (United States); He Gaohong [State Key Laboratory of Fine Chemicals, R and D Center of Membrane Science and Technology, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Deng Yulin, E-mail: yulin.deng@chbe.gatech.edu [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0620 (United States)

    2012-06-15

    To increase the photoresponsive and gas sensing properties of ZnO nanofibers under UV illumination, Au nanoparticles were introduced to the ZnO nanofibers (Au/ZnO) using electrospinning technique. It is found that adding Au nanoparticles into the ZnO nanofibers enhances significantly the photoresponse and makes the nanofibers also respond to visible light. The gas sensing performance with the assist of UV irradiation at room temperature was also improved greatly, e.g., the sensor response (SR) for 5 ppm ethanol increases from 0.12 to 0.31 by introducing 0.20 mol% of Au in ZnO nanofibers. The improvement of gas sensing performance is attributed to the enhanced photocatalytic reactions of organic gases on the Au/ZnO nanofibers surface. In addition, the sensitive behaviors of the nanofibers to ethanol, benzene, toluene and acetone under UV irradiation with different wavelengths were investigated and compared as well. Highlights: Black-Right-Pointing-Pointer Au/ZnO nanofiber sensors were successfully prepared using electrospinning. Black-Right-Pointing-Pointer The Au/ZnO sensors respond not only to UV light but also to visible light. Black-Right-Pointing-Pointer The response to organic analyte at room temperature is also greatly improved. Black-Right-Pointing-Pointer Schottky junction between Au and ZnO is one key for the improvement of sensing.

  4. Analytical Calculation of Sensing Parameters on Carbon Nanotube Based Gas Sensors

    Directory of Open Access Journals (Sweden)

    Elnaz Akbari

    2014-03-01

    Full Text Available Carbon Nanotubes (CNTs are generally nano-scale tubes comprising a network of carbon atoms in a cylindrical setting that compared with silicon counterparts present outstanding characteristics such as high mechanical strength, high sensing capability and large surface-to-volume ratio. These characteristics, in addition to the fact that CNTs experience changes in their electrical conductance when exposed to different gases, make them appropriate candidates for use in sensing/measuring applications such as gas detection devices. In this research, a model for a Field Effect Transistor (FET-based structure has been developed as a platform for a gas detection sensor in which the CNT conductance change resulting from the chemical reaction between NH3 and CNT has been employed to model the sensing mechanism with proposed sensing parameters. The research implements the same FET-based structure as in the work of Peng et al. on nanotube-based NH3 gas detection. With respect to this conductance change, the I–V characteristic of the CNT is investigated. Finally, a comparative study shows satisfactory agreement between the proposed model and the experimental data from the mentioned research.

  5. FBG sensing temperature characteristic and application in oil/gas down-hole measurement

    Institute of Scientific and Technical Information of China (English)

    Shaomin LI; Xiaoying LIU; You LI; Shenlong YANG; Chong LIU

    2009-01-01

    Fiber Bragg gratings (FBGs) have been used to sense numerous parameters such as strain, temperature, and pressure. Cost-effective multipoint measurements have been achieved by connecting FBGs in parallel, serial, and other topologies as well as by using spatial, wavelength, and time-domain multiplexing techniques. This paper presents a method of measuring temperature of the oil/gas down-hole. Detailed contents include the basic theory and characteristics of fiber gratings, analysis of the sensing mechanism of fiber-optic gratings, and the cross-sensitivity effect between temperature and strain; the method of making the light-source of the fiber-optic gratings and the technology of measuring wavelength shift, building an experimental system of the temperature measurement, and dealing with the experimental data. The paper makes a comparison of several kinds of FBG sensing systems used in oil/gas down-hole to measure temperature and the analysis of the experimental results of building the temperature measurement experimental sys-tem. It demonstrates that the fiber-optic grating sensing method is the best choice in all methods of measuring temperature in oil/gas down-hole, which has a brilliant applied prospect.

  6. Contribution of solid fuel, gas combustion, or tobacco smoke to indoor air pollutant concentrations in Irish and Scottish homes.

    Science.gov (United States)

    Semple, S; Garden, C; Coggins, M; Galea, K S; Whelan, P; Cowie, H; Sánchez-Jiménez, A; Thorne, P S; Hurley, J F; Ayres, J G

    2012-06-01

      There are limited data describing pollutant levels inside homes that burn solid fuel within developed country settings with most studies describing test conditions or the effect of interventions. This study recruited homes in Ireland and Scotland where open combustion processes take place. Open combustion was classified as coal, peat, or wood fuel burning, use of a gas cooker or stove, or where there is at least one resident smoker. Twenty-four-hour data on airborne concentrations of particulate matter<2.5 μm in size (PM2.5), carbon monoxide (CO), endotoxin in inhalable dust and carbon dioxide (CO2), together with 2-3 week averaged concentrations of nitrogen dioxide (NO2) were collected in 100 houses during the winter and spring of 2009-2010. The geometric mean of the 24-h time-weighted-average (TWA) PM2.5 concentration was highest in homes with resident smokers (99 μg/m3--much higher than the WHO 24-h guidance value of 25 μg/m3). Lower geometric mean 24-h TWA levels were found in homes that burned coal (7 μg/m3) or wood (6 μg/m3) and in homes with gas cookers (7 μg/m3). In peat-burning homes, the average 24-h PM2.5 level recorded was 11 μg/m3. Airborne endotoxin, CO, CO2, and NO2 concentrations were generally within indoor air quality guidance levels. Little is known about indoor air quality (IAQ) in homes that burn solid or fossil-derived fuels in economically developed countries. Recent legislative changes have moved to improve IAQ at work and in enclosed public places, but there remains a real need to begin the process of quantifying the health burden that arises from indoor air pollution within domestic environments. This study demonstrates that homes in Scotland and Ireland that burn solid fuels or gas for heating and cooking have concentrations of air pollutants generally within guideline levels. Homes where combustion of cigarettes takes place have much poorer air quality. © 2011 John Wiley & Sons A/S.

  7. Individual hollow and mesoporous aero-graphitic microtube based devices for gas sensing applications

    Science.gov (United States)

    Lupan, Oleg; Postica, Vasile; Marx, Janik; Mecklenburg, Matthias; Mishra, Yogendra K.; Schulte, Karl; Fiedler, Bodo; Adelung, Rainer

    2017-06-01

    In this work, individual hollow and mesoporous graphitic microtubes were integrated into electronic devices using a FIB/SEM system and were investigated as gas and vapor sensors by applying different bias voltages (in the range of 10 mV-1 V). By increasing the bias voltage, a slight current enhancement is observed, which is mainly attributed to the self-heating effect. A different behavior of ammonia NH3 vapor sensing by increasing the applied bias voltage for hollow and mesoporous microtubes with diameters down to 300 nm is reported. In the case of the hollow microtube, an increase in the response was observed, while a reverse effect has been noticed for the mesoporous microtube. It might be explained on the basis of the higher specific surface area (SSA) of the mesoporous microtube compared to the hollow one. Thus, at room temperature when the surface chemical reaction rate (k) prevails on the gas diffusion rate (DK) the structures with a larger SSA possess a higher response. By increasing the bias voltage, i.e., the overall temperature of the structure, DK becomes a limiting step in the gas response. Therefore, at higher bias voltages the larger pores will facilitate an enhanced gas diffusion, i.e., a higher gas response. The present study demonstrates the importance of the material porosity towards gas sensing applications.

  8. Au sensitized ZnO nanorods for enhanced liquefied petroleum gas sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Nakate, U.T., E-mail: umesh.nakate@gmail.com [Department of Applied Physics, Defence Institute of Advanced Technology, Deemed University, Pune 411025 (India); Bulakhe, R.N.; Lokhande, C.D. [Department of Physics, Thin films Physics Laboratory, Shivaji University Kolhapur 416004 (India); Kale, S.N. [Department of Applied Physics, Defence Institute of Advanced Technology, Deemed University, Pune 411025 (India)

    2016-05-15

    Highlights: • We studied ZnO nanorods film for liquefied petroleum gas (LPG) sensing. • The Au sensitization on ZnO nanorods gives improved LPG sensing response. • The Au–ZnO shows 48% LPG response for 1040 ppm with fast response time of 50 S. • We proposed schematic for sensing mechanism using band diagram. - Abstract: The zinc oxide (ZnO) nanorods have grown on glass substrate by spray pyrolysis deposition (SPD) method using zinc acetate solution. The phase formation, surface morphology and elemental composition of ZnO films have been investigated using X-ray diffraction, field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and energy dispersive X-ray (EDX) techniques. The liquefied petroleum gas (LPG) sensing response was remarkably improved by sensitization of gold (Au) surface noble metal on ZnO nanorods film. Maximum LPG response of 21% was observed for 1040 ppm of LPG, for pure ZnO nanorods sample. After Au sensitization on ZnO nanorods film sample, the LPG response greatly improved up to 48% at operating temperature 623 K. The improved LPG response is attributed Au sensitization with spill-over mechanism. Proposed model for LPG sensing mechanism discussed.

  9. Applied combustion

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-31

    From the title, the reader is led to expect a broad practical treatise on combustion and combustion devices. Remarkably, for a book of modest dimension, the author is able to deliver. The text is organized into 12 Chapters, broadly treating three major areas: combustion fundamentals -- introduction (Ch. 1), thermodynamics (Ch. 2), fluid mechanics (Ch. 7), and kinetics (Ch. 8); fuels -- coal, municipal solid waste, and other solid fuels (Ch. 4), liquid (Ch. 5) and gaseous (Ch. 6) fuels; and combustion devices -- fuel cells (Ch. 3), boilers (Ch. 4), Otto (Ch. 10), diesel (Ch. 11), and Wankel (Ch. 10) engines and gas turbines (Ch. 12). Although each topic could warrant a complete text on its own, the author addresses each of these major themes with reasonable thoroughness. Also, the book is well documented with a bibliography, references, a good index, and many helpful tables and appendices. In short, Applied Combustion does admirably fulfill the author`s goal for a wide engineering science introduction to the general subject of combustion.

  10. Combustion gas from biomass - innovative plant concepts on the basis of circulating fluidized bed gasification; Brenngas aus Biomasse - innovative Anlagenkonzepte auf Basis der Zirkulierenden Wirbelschichtvergasung

    Energy Technology Data Exchange (ETDEWEB)

    Greil, C.; Hirschfelder, H. [Lurgi Umwelt GmbH, Frankfurt am Main (Germany)

    1998-09-01

    The contribution describes the applications of the Lurgi-ZWS gas generator. There are three main fields of application: Direct feeding of combustion gas, e.g. into a rotary kiln, as a substitute for coal or oil, without either dust filtering or gas purification. - Feeding of the combustion gas into the steam generator of a coal power plant after dust filtering and, if necessar, filtering of NH{sub 3} or H{sub 2}S. - Combustion in a gas turbine or gas engine after gas purification according to specifications. The applications are described for several exemplary projects. (orig./SR) [Deutsch] Im folgenden wird ueber die Anwendung des Lurgi-ZWS-Gaserzeugers berichtet. Nach heutiger Sicht stehen drei Anwendungsgebiete im Vordergrund: - direkte Einspeisung des Brenngases in z.B. einen Zementdrehrohrofen zur Substitution von Kohle oder Oel, ohne Entstaubung und Gasreinigung. - Einspeisung des Brenngases nach Entstaubung und gegebenenfalls Entfernung weiterer Komponenten wie NH{sub 3} oder H{sub 2}S in den Dampferzeuger eines Kohlekraftwerkes - Einsatz des Brenngases in einer Gasturbine oder Gasmotor nach spezifikationsgerechter Gasreinigung. Die aufgefuehrten Einsatzmoeglichkeiten werden am Beispiel von Projekten beschrieben. (orig./SR)

  11. Biomass Combustion Control and Stabilization Using Low-Cost Sensors

    Directory of Open Access Journals (Sweden)

    Ján Piteľ

    2013-01-01

    Full Text Available The paper describes methods for biomass combustion process control and burning stabilization based on low-cost sensing of carbon monoxide emissions and oxygen concentration in the flue gas. The designed control system was tested on medium-scale biomass-fired boilers and some results are evaluated and presented in the paper.

  12. Multi-Walled Carbon Nanotube-Doped Tungsten Oxide Thin Films for Hydrogen Gas Sensing

    Directory of Open Access Journals (Sweden)

    Adisorn Tuantranont

    2010-08-01

    Full Text Available In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT-doped tungsten oxide (WO3 thin films by means of the powder mixing and electron beam (E-beam evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO3 thin film exhibits high sensitivity and selectivity to hydrogen. Thus, MWCNT doping based on E-beam co-evaporation was shown to be an effective means of preparing hydrogen gas sensors with enhanced sensing and reduced operating temperatures. Creation of nanochannels and formation of p-n heterojunctions were proposed as the sensing mechanism underlying the enhanced hydrogen sensitivity of this hybridized gas sensor. To our best knowledge, this is the first report on a MWCNT-doped WO3 hydrogen sensor prepared by the E-beam method.

  13. Multi-walled carbon nanotube-doped tungsten oxide thin films for hydrogen gas sensing.

    Science.gov (United States)

    Wongchoosuk, Chatchawal; Wisitsoraat, Anurat; Phokharatkul, Ditsayut; Tuantranont, Adisorn; Kerdcharoen, Teerakiat

    2010-01-01

    In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT)-doped tungsten oxide (WO(3)) thin films by means of the powder mixing and electron beam (E-beam) evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO(3) thin film exhibits high sensitivity and selectivity to hydrogen. Thus, MWCNT doping based on E-beam co-evaporation was shown to be an effective means of preparing hydrogen gas sensors with enhanced sensing and reduced operating temperatures. Creation of nanochannels and formation of p-n heterojunctions were proposed as the sensing mechanism underlying the enhanced hydrogen sensitivity of this hybridized gas sensor. To our best knowledge, this is the first report on a MWCNT-doped WO(3) hydrogen sensor prepared by the E-beam method.

  14. Synergistic improvement of gas sensing performance by micro-gravimetrically extracted kinetic/thermodynamic parameters.

    Science.gov (United States)

    Guo, Shuanbao; Xu, Pengcheng; Yu, Haitao; Cheng, Zhenxing; Li, Xinxin

    2015-03-10

    A novel method is explored for comprehensive design/optimization of organophosphorus sensing material, which is loaded on mass-type microcantilever sensor. Conventionally, by directly observing the gas sensing response, it is difficult to build quantitative relationship with the intrinsic structure of the material. To break through this difficulty, resonant cantilever is employed as gravimetric tool to implement molecule adsorption experiment. Based on the sensing data, key kinetic/thermodynamic parameters of the material to the molecule, including adsorption heat -ΔH°, adsorption/desorption rate constants Ka and Kd, active-site number per unit mass N' and surface coverage θ, can be quantitatively extracted according to physical-chemistry theories. With gaseous DMMP (simulant of organophosphorus agents) as sensing target, the optimization route for three sensing materials is successfully demonstrated. Firstly, a hyper-branched polymer is evaluated. Though suffering low sensitivity due to insufficient N', the bis(4-hydroxyphenyl)-hexafluoropropane (BHPF) sensing-group exhibits satisfactory reproducibility due to appropriate -ΔH°. To achieve more sensing-sites, KIT-5 mesoporous-silica with higher surface-area is assessed, resulting in good sensitivity but too high -ΔH° that brings poor repeatability. After comprehensive consideration, the confirmed BHPF sensing-group is grafted on the KIT-5 carrier to form an optimized DMMP sensing nanomaterial. Experimental results indicate that, featuring appropriate kinetic/thermodynamic parameters of -ΔH°, Ka, Kd, N' and θ, the BHPF-functionalized KIT-5 mesoporous silica exhibits synergistic improvement among reproducibility, sensitivity and response/recovery speed. The optimized material shows complete signal recovery, 55% sensitivity improvement than the hyper-branched polymer and 2∼3 folds faster response/recovery speed than the KIT-5 mesoporous silica.

  15. Combustion physics

    Science.gov (United States)

    Jones, A. R.

    1985-11-01

    Over 90% of our energy comes from combustion. By the year 2000 the figure will still be 80%, even allowing for nuclear and alternative energy sources. There are many familiar examples of combustion use, both domestic and industrial. These range from the Bunsen burner to large flares, from small combustion chambers, such as those in car engines, to industrial furnaces for steel manufacture or the generation of megawatts of electricity. There are also fires and explosions. The bountiful energy release from combustion, however, brings its problems, prominent among which are diminishing fuel resources and pollution. Combustion science is directed towards finding ways of improving efficiency and reducing pollution. One may ask, since combustion is a chemical reaction, why physics is involved: the answer is in three parts. First, chemicals cannot react unless they come together. In most flames the fuel and air are initially separate. The chemical reaction in the gas phase is very fast compared with the rate of mixing. Thus, once the fuel and air are mixed the reaction can be considered to occur instantaneously and fluid mechanics limits the rate of burning. Secondly, thermodynamics and heat transfer determine the thermal properties of the combustion products. Heat transfer also plays a role by preheating the reactants and is essential to extracting useful work. Fluid mechanics is relevant if work is to be performed directly, as in a turbine. Finally, physical methods, including electric probes, acoustics, optics, spectroscopy and pyrometry, are used to examine flames. The article is concerned mainly with how physics is used to improve the efficiency of combustion.

  16. Theoretical Study on the Effect of Dibutyl Phthalate on the Generation of Combustible Gas in the Combustion of Propellant%DBP对发射药燃烧可燃气体产物影响的理论研究

    Institute of Scientific and Technical Information of China (English)

    郑文芳; 郭长平; 蔺向阳; 潘仁明

    2011-01-01

    采用最小自由能算法理论研究了邻苯二甲酸二丁酯(DBP)对单基发射药燃烧生成可燃气体产物的影响规律,并利用定容燃烧试验对理论研究结果进行了验证.结果表明,配方中DBP含量超过某一临界值时,发射药燃烧会有固态游离碳生成;可燃气体的生成量随着DBP含量的升高先逐渐增加,并在DBP含量临界值时(生成游离碳)达到最大值,然后逐渐降低;当DBP含量低于临界值时,提高硝化纤维素的含氮量,可减少可燃气体生成量;当DBP含量高于临界值时,提高硝化纤维素含氮量和降低燃烧平衡压力,会增加可燃气体生成量;理论研究结果与实验结果较一致.建立了发射药燃烧游离碳生成的DBP含量临界值与硝化纤维素含氮量、燃烧平衡压力之间的关系函数.%Effects of dibutyl phthalate (DBP) on combustible gas products of single-base propellant were studied by computational method of minimum free energy, and the computational results were verified through closed vessel experiments. The results show that the combustion of propellant can generate free carbon residue when the DBP content in propellant exceeds a critical value. As the DBP content in propellant increases, the yield of combustible gas increases, and reaches a maximum at the DBP critical content, then decreases. When the DBP content is lower than the critical content, the amounts of combustible gas can be decreased with the increase of the nitrogen content of nitrocellulose. While the DBP content is higher than the critical content, the amounts of combustible gas can be increased as the descent of combustion equilibrium pressure or heightening of nitrogen content of nitrocellulose. The computational results and experimental results are consistent. In addition, the function of the DBP critical content and the nitrogen content of nitrocellulose, combustion pressure is established based on the computational results.

  17. Anatomy of an upgraded pulverized coal facility: Combustion modification through flue gas scrubbing

    Energy Technology Data Exchange (ETDEWEB)

    Watts, J.U. [Dept. of Energy, Pittsburgh, PA (United States). Federal Energy Technology Center; Savichky, W.J.; O`Dea, D.T. [New York State Electric and Gas Corp., Binghamton, NY (United States)

    1997-12-31

    Regeneration is a biological term for formation or creating anew. In the case of Milliken station, a species of steam generation (Tangentus coali) regeneration refers to refitting critical systems with the latest technological advances to reduce emissions while maintaining or improving performance. The plant has undergone a series of operations which provided anatomical changes as well as a face lift. Each of the two units were place in suspended animation (outage) to allow these changes to be made. The paper describes the project which includes retrofitting combustion systems, pulverizers, boiler liners, scrubbers, and control room. This retrofit is meant to increase thermal efficiency while reducing the formation of nitrogen oxides.

  18. Experimental study and numerical simulation of gas-particle flows with radial bias combustion and centrally fuel rich swirl burners

    Institute of Scientific and Technical Information of China (English)

    LI Zheng-qi; ZHOU Jue; CHEN Zhi-chao; SUN Rui; QIN Yu-kun

    2008-01-01

    Numerical simulation is applied to gas-particle flows of the primary and the secondary air ducts and burner region, and of two kinds of swirl burners. The modeling results of Radial Bias Combustion (RBC) burn-er well agreed with the data from the three-dimensional Phase-Doppler anemometry (PDA) experiment by Li, et al. The modeling test conducted in a 1025 t/h boiler was to study the quality of aerodynamics for a Central Fuel Rich (CFR) burner, and the Internal Recirculation Zone (IRZ) was measured. In addition, gas-particle flows with a CFR burner were investigated by numerical simulation, whose results accorded with the test data funda-mentally. By analyzing the distribution of gas velocity and trajectories of particles respectively, it is found that the primary air's rigidity of CFR burner is stronger than that of RBC burner, and the primary air mixes with the secondary air later. Furthermore, high concentration region of pulverized coal exists in the burner's central zone whose atmosphere is reduced, and trajectories of particles in IRZ of CFR burner are longer than that of RBC burner. They are favorable to coal's ignition and the reduction of NOx emission.

  19. Fast spatially resolved exhaust gas recirculation (EGR) distribution measurements in an internal combustion engine using absorption spectroscopy.

    Science.gov (United States)

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E; Perfetto, Anthony; Geckler, Sam; Partridge, William P

    2015-09-01

    Exhaust gas recirculation (EGR) in internal combustion engines is an effective method of reducing NOx emissions while improving efficiency. However, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder non-uniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. A sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the intake manifold of an operating engine. The probe promotes the development of more efficient and higher-performance engines by resolving high-speed in situ CO2 concentration at various locations in the intake manifold. The study employed mid-infrared light sources tuned to an absorption band of CO2 near 4.3 μm, an industry standard species for determining EGR fraction. The calibrated probe was used to map spatial EGR distributions in an intake manifold with high accuracy and monitor cycle-resolved cylinder-specific EGR fluctuations at a rate of up to 1 kHz.

  20. A Novel High-Heat Transfer Low-NO{sub x} Natural Gas Combustion System. Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, H.

    2004-01-01

    A novel high-heat transfer low NO(sub x) natural gas combustion system. The objectives of this program are to research, develop, test, and commercialize a novel high-heat transfer low-NO{sub x} natural gas combustion system for oxygen-, oxygen-enriched air, and air-fired furnaces. This technology will improve the process efficiency (productivity and product quality) and the energy efficiency of high-temperature industrial furnaces by at least 20%. GTI's high-heat transfer burner has applications in high-temperature air, oxygen-enriched air, and oxygen furnaces used in the glass, metals, cement, and other industries. Development work in this program is focused on using this burner to improve the energy efficiency and productivity of glass melting furnaces that are major industrial energy consumers. The following specific project objectives are defined to provide a means of achieving the overall project objectives. (1) Identify topics to be covered, problems requiring attention, equipment to be used in the program, and test plans to be followed in Phase II and Phase III. (2) Use existing codes to develop models of gas combustion and soot nucleation and growth as well as a thermodynamic and parametric description of furnace heat transfer issues. (3) Conduct a parametric study to confirm the increase in process and energy efficiency. (4) Design and fabricate a high-heat transfer low-NOx natural gas burners for laboratory, pilot- and demonstration-scale tests. (5) Test the high-heat transfer burner in one of GTI's laboratory-scale high-temperature furnaces. (6) Design and demonstrate the high-heat transfer burner on GTI's unique pilot-scale glass tank simulator. (7) Complete one long term demonstration test of this burner technology on an Owens Corning full-scale industrial glass melting furnace. (8) Prepare an Industrial Adoption Plan. This Plan will be updated in each program Phase as additional information becomes available. The Plan will include

  1. Review of homogeneous charge compression ignition (HCCI) combustion engines and exhaust gas recirculation (EGR) effects on HCCI

    Science.gov (United States)

    Akma Tuan Kamaruddin, Tengku Nordayana; Wahid, Mazlan Abdul; Sies, Mohsin Mohd

    2012-06-01

    This paper describes the development in ICE which leads to the new advanced combustion mode named Homogeneous Charge Compression Ignition (HCCI). It explains regarding the theory and working principle of HCCI plus the difference of the process in gasoline and diesel fuelled engines. Many of pioneer and recent research works are discussed to get the current state of art about HCCI. It gives a better indication on the potential of this method in improving the fuel efficiency and emission produced by the vehicles' engine. Apart from the advantages, the challenges and future trend of this technology are also included. HCCI is applying few types of control strategy in producing the optimum performance. This paper looks into Exhaust Gas Recirculation (EGR) as one of the control strategies.

  2. Preliminary analysis of selected gas dynamic problems. [space shuttle main engine main combustion transients and IUS nozzle flow

    Science.gov (United States)

    Prozan, R. J.; Farmer, R. C.

    1985-01-01

    The VAST computer code was used to analyze SSME main combustion chamber start-up transients and the IUS flow field for a damaged nozzle was investigated to better understand the gas dynamic considerations involved in vehicle problems, the effect of start transients on the nozzle flow field for the SSME, and the possibility that a damaged nozzle could account for the acceleration anomaly noted on IUS burn. The results obtained were compared with a method of characteristics prediction. Pressure solutions from both codes were in very good agreement and the Mach number solution on the nozzle centerline deviates substantially for the high expansions for the SSME. Since this deviation was unexpected, the phenomenon is being further examined.

  3. Natural Gas Variability In California: Environmental Impacts And Device Performance Combustion Modeling of Pollutant Emissions From a Residential Cooking Range

    Energy Technology Data Exchange (ETDEWEB)

    Tonse, S. R.; Singer, B. C.

    2011-07-01

    As part of a larger study of liquefied natural gas impacts on device performance and pollutant emissions for existing equipment in California, this report describes a cmoputer modeling study of a partially premixed flame issueing from a single cooktop burner port. The model consisted of a reactive computational fluid dynamics three-dimensional spatial grid and a 71-species chemical mechanism with propane combustion capability. Simulations were conducted with a simplified fuel mixture containing methane, ethane, and propane in proportions that yield properties similar to fuels distributed throughout much of California now and in recent years (baseline fuel), as well as with two variations of simulated liquefied natural gas blends. A variety of simulations were conducted with baseline fuel to explore the effect of several key parameters on pollutant formation and other flame characteristics. Simulations started with fuel and air issuing through the burner port, igniting, and continuing until the flame was steady with time. Conditions at this point were analyzed to understand fuel, secondary air and reaction product flows, regions of pollutant formation, and exhaust concentrations of carbon monoxide, nitric oxide and formaldehyde. A sensitivity study was conducted, varying the inflow parameters of this baseline gs about real-world operating conditions. Flame properties responded as expected from reactive flow theory. In the simulation, carbon monoxide levels were influenced more by the mixture's inflow velocity than by the gas-to-air ratio in the mixture issuing from the inflow port. Additional simulations were executed at two inflow conditions - high heat release and medium heat release - to examine the impact of replacing the baseline gas with two mixtures representative of liquefied natural gas. Flame properties and pollutant generation rates were very similar among the three fuel mixtures.

  4. Combustion development of an industrial scale burner, with particular reference to coal blends and co-firing coal with natural gas and sawdust

    Energy Technology Data Exchange (ETDEWEB)

    Allen, G. [International Combustion Limited, Derby (United Kingdom). Rolls Royce Industrial Power Group

    1998-12-31

    Described herein are the results of pulverised coal combustion experiments performed on a 35 MWth low NO{sub x} burner installed in International Combustion`s large scale combustion test facility. In-flame and furnace exit combustion/emissions species and temperature measurements were taken during firing trials with: different coal blends; a coal-wood dust fuel blend; coal and natural gas `In-Burner` co-firing. The NO{sub x} and unburned carbon in ash results generated from the coal blend tests were shown to correlate well against fuel ratio. The gas co-firing results confirmed low momentum gas injection along the burner axis as optimum. This reduced NO{sub x} by 16% whilst unburned carbon in ash fell from 3 to 1.5%. Larger NO{sub x} reductions were anticipated by virtue of activating an `In-Burner` gas reburn de-NO{sub x} process. A 1/2th scale isothermal low NO{sub x} burner model was used to characterise pulverized coal particle (PF) dynamics in the near burner region. Laser sheet velocimetry and laser doppler anemometry measurements indicated that the larger PF particles follow a straight trajectory and penetrate the burner internal recirculation zone. Conversely, the smaller PF particles are drawn radially outwards into the shear layer between the burner PA and SA flow streams to initiate combustion. A CFD model of this burner was validated against the experimental data. This exercise highlighted the importance of specifying accurate CFD model inlet boundary conditions, adopting fine grids, and selecting appropriate turbulence models. This mathematical model was subsequently used to derive new flame stabiliser concepts, which were tested on a full size burner. 9 refs., 27 figs., 8 tabs.

  5. Growth and toxic gas sensing properties of poly(urethaneimide) thin films.

    Science.gov (United States)

    Youssef, Ismail Ben; Sarry, Frederic; Nysten, Bernard; Alexieva, Gergana; Strashilov, Vesselin; Kolev, Iliyan; Alem, Halima

    2016-06-01

    In this work we present a study on the growth and the gas sensing properties of poly(urethane imide) thin films. We first deeply characterized by atomic force microscopy (AFM) the nanostructuration of the poly(urethane imide) holding different amine groups. We further studied the interaction between highly toxic gases such as hexamethyleneimine (HMI) and pyridine and the polymer by using an unconventional method based on Quartz Crystal Microbalance (QCM) measurement. We showed for the first time that weak interactions, i.e. hydrogen bonding between the gas molecules and the polymer film allow the diffusion of the gas molecule deep in the polymeric film and the recovery of the film once the gas molecules leave the sensor. This first work paves a new way for the design of a completely recoverable sensor able to detect highly toxic gases for environmental concern.

  6. Superior selectivity and sensitivity of blue phosphorus nanotubes in gas sensing applications

    KAUST Repository

    Montes Muñoz, Enrique

    2017-05-23

    On the basis of first principles calculations, we study the adsorption of CO, CO2, NH3, NO, and NO2 molecules on armchair and zigzag blue phosphorus nanotubes. The nanotubes are found to surpass the gas sensing performance of other one-dimensional materials, in particular Si nanowires and carbon nanotubes, and two-dimensional materials, in particular graphene, phosphorene, and MoS2. Investigation of the energetics of the gas adsorption and induced charge transfers indicates that blue phosphorus nanotubes are highly sensitive to N-based molecules, in particular NO2, due to covalent bonding. The current–voltage characteristics of nanotubes connected to Au electrodes are derived by the non-equilibrium Green\\'s function formalism and used to quantitatively evaluate the change in resistivity upon gas adsorption. The observed selectivity and sensitivity properties make blue phosphorus nanotubes superior gas sensors for a wide range of applications.

  7. Studies on gas sensing performance of pure and modified barium strontium titanate thick film resistors

    Indian Academy of Sciences (India)

    G H Jain; L A Patil; P P Patil; U P Mulik; K R Patil

    2007-02-01

    Barium strontium titanate ((Ba0.87Sr0.13)TiO3–BST) ceramic powder was prepared by mechanochemical process. The thick films of different thicknesses of BST were prepared by screen-printing technique and gas-sensing performance of these films was tested for various gases. The films showed highest response and selectivity to ammonia gas. The effect of film thickness on gas response was also studied. As prepared BST thick films were surface modified by dipping them into an aqueous solution of titanium chloride (TiCl3) for different intervals of time. Surface modification shifted response to H2S gas suppressing the responses to ammonia and other gases. The surface modification, using dipping process, altered the adsorbate–adsorbent interactions, which gave the unusual sensitivity and selectivity effect. Sensitivity, selectivity, thermal stability, response and recovery time of the sensor were measured and presented.

  8. Development of pressurised fluidised bed combustion technique for coal-fired gas/steam processes; Entwicklung der Druckwirbelschicht-Feuerungstechnik fuer kohlegefeuerte Gas-Dampfprozesse

    Energy Technology Data Exchange (ETDEWEB)

    Pitt, R.; Steven, H.

    1992-12-31

    The investigations for the development of the pressurized fluidized bed technique have shown that it is possible, in principle, to keep within the emission limits with the steady state pressurised fluidised bed combustion, even at low part load. However, the construction expense is considerable and the type of coal and grain size must comply relatively exactly with the design values. Not every fuel is suitable for fluidised bed combustion regarding emission. The most important parameter for emission is the temperature profile for this component, which should be as even as possible at a high temperature level. A sufficient dwell time of the gas and the particles is decisive for CO emission, where a minimum reaction time is required for both phases. (orig.) [Deutsch] Die Untersuchungen zur Entwicklung der Druckwirbelschichttechnik haben gezeigt, dass es prinzipiell moeglich ist, mit der stationaeren druckaufgeladenen Wirbelschichtfeuerung die Emissionsgrenzwerte auch bei geringer Teillast einzuhalten, allerdings ist der bauliche Aufwand erheblich und auch die Kohleart und Koernung muessen relativ genau den Auslegungswerten entsprechen. Auch hinsichtlich der Emissionen ist nicht jeder Brennstoff fuer die Wirbelschichtfeuerung geeignet. Wichtigster Einflusspartner auf die Emission ist auch bei dieser Komponente das Temperaturprofil, das moeglichst gleichmaessig auf hohem Temperaturniveau liegen sollte. Ausreichende Verweilzeit des Gases und der Partikel sind fuer die CO-Emission entscheidend, wobei fuer beide Phasen eine Mindestreaktionszeit erforderlich ist. (orig.)

  9. Contribution of solid fuel, gas combustion, or tobacco smoke to indoor air pollutant concentrations in Irish and Scottish homes

    Energy Technology Data Exchange (ETDEWEB)

    Semple, S.; Garden, C. (Univ. of Aberdeen. Scottish Centre for Indoor Air, Div. of Applied Health Sciences (United Kingdom)); Galea, K.S.; Cowie, H.; Hurley, J.F.; Sanchez-Jimenez, A. (Scottish Centre for Indoor Air. Institute of Occupational Medicine, Edinburgh (United Kingdom)); Whelan, P.; Coggins, M. (National Univ. of Ireland Galway (Ireland)); Thorne, P.S. (Univ. of Iowa. Environmental Health Sciences Research Center, Iowa City, IA (United States)); Ayres, J.G. (Univ. of Birmingham. Institute of Occupational and Environmental Medicine (United Kingdom))

    2012-06-15

    There are limited data describing pollutant levels inside homes that burn solid fuel within developed country settings with most studies describing test conditions or the effect of interventions. This study recruited homes in Ireland and Scotland where open combustion processes take place. Open combustion was classified as coal, peat, or wood fuel burning, use of a gas cooker or stove, or where there is at least one resident smoker. Twenty-four-hour data on airborne concentrations of particulate matter <2.5 mu in size (PM{sub 2.5}), carbon monoxide (CO), endotoxin in inhalable dust and carbon dioxide (CO{sub 2}), together with 2-3 week averaged concentrations of nitrogen dioxide (NO{sub 2}) were collected in 100 houses during the winter and spring of 2009-2010. The geometric mean of the 24-h time-weighted-average (TWA) PM{sub 2.5} concentration was highest in homes with resident smokers (99 mu/m3- much higher than the WHO 24-h guidance value of 25 mu/m3). Lower geometric mean 24-h TWA levels were found in homes that burned coal (7 mu/m3) or wood (6 mu/m3) and in homes with gas cookers (7 mu/m3). In peat-burning homes, the average 24-h PM{sub 2.5} level recorded was 11 mu/m3. Airborne endotoxin, CO, CO{sub 2}, and NO{sub 2} concentrations were generally within indoor air quality guidance levels. (Author)

  10. 简述可燃气体报警器的检测和应用%Detection and Application of Combustible Gas Alarm

    Institute of Scientific and Technical Information of China (English)

    吴珂; 黄武; 夏一峰

    2012-01-01

    可燃气体报警器广泛应用于油库、燃气、化工、石油等存在可燃气体的行业,由报警仪与探测器组成,用于检测室内外危险场所的泄露情况,是保证人身安全和安全生产不可或缺的仪器.本文首先介绍了可燃气体报警器的分类及检测对象和可燃气体报警系统,然后详细分析了可燃气体报警器的检测和应用,为进一步研究提供依据.%The combustible gas detector is widely used in oil, gas, chemical and oil industries, and it is composed by the alarm and detector. It is used to detect leaks of inside and outside the hazardous area and is indispensable equipment to ensure personal safety and safety. This article first describes the classification and detection object of combustible gas alarm and alarm system for combustible gases, and makes a detailed analysis of the detection and application of combustible gas alarm, providing the basis for further study.

  11. Nanocomposite oxygen carriers for chemical-looping combustion of sulfur-contaminated synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Rahul D. Solunke; Goetz Veser [United States Department of Energy, Pittsburgh, PA (United States). National Energy Technology Laboratory

    2009-09-15

    Chemical-looping combustion (CLC) is an emerging technology for clean combustion. We have previously demonstrated that the embedding of metal nanoparticles into a nanostructured ceramic matrix can result in unusually active and sinter-resistant nanocomposite oxygen carrier materials for CLC, which combine the high reactivity of metals with the high-temperature stability of ceramics. In the present study, we investigate the effect of H{sub 2}S in a typical coal-derived syngas on the stability and redox kinetics of Ni- and Cu-based nanostructured oxygen carriers. Both carriers show excellent structural stability and only mildly changed redox kinetics upon exposure to H{sub 2}S, despite a significant degree of sulfide formation. Surprisingly, partial sulfidation of the support results in a strong increase in oxygen carrier capacity in both cases because of the addition of a sulfide-sulfate cycle. Overall, the carriers show great potential for use in CLC of high-sulfur fuels. 21 refs., 13 figs. 1 tab.

  12. Brayton cycle for internal combustion engine exhaust gas waste heat recovery

    Directory of Open Access Journals (Sweden)

    J Galindo

    2015-06-01

    Full Text Available An average passenger car engine effectively uses about one-third of the fuel combustion energy, while the two-thirds are wasted through exhaust gases and engine cooling. It is of great interest to automotive industry to recover some of this wasted energy, thus increasing the engine efficiency and lowering fuel consumption and contamination. Waste heat recovery for internal combustion engine exhaust gases using Brayton cycle machine was investigated. The principle problems of application of such a system in a passenger car were considered: compressor and expander machine selection, machine size for packaging under the hood, efficiency of the cycle, and improvement of engine efficiency. Important parameters of machines design have been determined and analyzed. An average 2-L turbocharged gasoline engine’s New European Driving Cycle points were taken as inlet points for waste heat recovery system. It is theoretically estimated that the recuperated power of 1515 W can be achieved along with 5.7% improvement in engine efficiency, at the point where engine power is 26550 W.

  13. Elemental and organic carbon in flue gas particles of various wood combustion systems

    Energy Technology Data Exchange (ETDEWEB)

    Gaegauf, C.; Schmid, M.; Guentert, P.

    2005-12-15

    The airborne particulate matter (PM) in the environment is of ever increasing concern to authorities and the public. The major fractions of particles in wood combustion processes are in the size less than 1 micron, typically in the range of 30 to 300 nm. Of specific interest is the content of the elemental carbon (EC) and organic carbon (OC) in the particles since these substances are known for its particular potential as carcinogens. Various wood combustion systems have been analysed (wood chip boiler, pellet boiler, wood log boiler, wood stove and open fire). The sampling of the particles was done by mean of a multi-stage particle sizing sampler cascade impactor. The impactor classifies the particles collected according to their size. The 7 stages classify the particles between 0.4 and 9 microns aerodynamic diameter. The analytical method for determining the content of EC and OC in the particles is based on coulometry. The coulometer measures the conductivity of CO{sub 2} released by oxidation of EC in the samples at 650 {sup o}C. The OC content is determined by pyrolysis of the particle samples in helium atmosphere.

  14. Thermal decomposition of selected chlorinated hydrocarbons during gas combustion in fluidized bed

    Directory of Open Access Journals (Sweden)

    Olek Malgorzata

    2013-01-01

    Full Text Available Abstract Background The process of thermal decomposition of dichloromethane (DCM and chlorobenzene (MCB during the combustion in an inert, bubbling fluidized bed, supported by LPG as auxiliary fuel, have been studied. The concentration profiles of C6H5CI, CH2Cl2, CO2, CO, NOx, COCl2, CHCl3, CH3Cl, C2H2, C6H6, CH4 in the flue gases were specified versus mean bed temperature. Results The role of preheating of gaseous mixture in fluidized bed prior to its ignition inside bubbles was identified as important factor for increase the degree of conversion of DCM and MCB in low bed temperature, in comparison to similar process in the tubular reactor. Conclusions Taking into account possible combustion mechanisms, it was identified that autoignition in bubbles rather than flame propagation between bubbles is needed to achieve complete destruction of DCM and MCB. These condition occurs above 900°C causing the degree of conversion of chlorine compounds of 92-100%.

  15. Microstructure and gas-sensing properties of sol-gel ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Musat, V. [Department of Metals and Materials Science, ' Dunarea de Jos' University of Galati, 800008 Galati (Romania)], E-mail: viorica.musat@ugal.ro; Rego, A.M. [Department of Chemical and Biological Engineering, CQFM, Technical University of Lisbon, 1049-001 Lisbon (Portugal); Monteiro, R.; Fortunato, E. [Department of Materials Science, CENIMAT, Faculty of Sciences and Technology, New University of Lisbon, Campus da Caparica, 2829-516 Caparica (Portugal)

    2008-02-15

    The paper presents the properties of zinc oxide thin films deposited on glass substrate via dip-coating technique. Zinc acetate dehydrate, ethanol and monoethanol amine were used as starting materials and N{sub 2} gas was used as thermal annealing atmosphere for film crystallization. The effect of withdrawal speed on the crystalline structure, morphology, zinc and nitrogen chemical states, optical, electrical and gas-sensing properties of the thin films has been investigated using X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, optical transmittance and photoreduction-ozone reoxidation data.

  16. Gas sensing properties of branched carbon nanotube-based structures using a novel low voltage emission.

    Science.gov (United States)

    Darbari, S; Azimi, S; Abdi, Y; Mohajerzadeh, S

    2012-11-01

    Branched carbon nanostructures have been successfully grown on interdigital comb-like structures for a gas sensing application. Field emission scanning electron microscopy has been utilized to investigate the morphology and structure of the grown nanostructures at different stages of growth process. Tunneling current of the fabricated sensor has been measured when a monotonically increasing voltage is applied between the electrodes. The effect of exposure to three different gases on the measured current has been studied. A data processing on the measured current voltage characteristics results in the evolution of various peaks at distinct voltages which depends on the type of the gas.

  17. Multi-Walled Carbon Nanotube-Doped Tungsten Oxide Thin Films for Hydrogen Gas Sensing

    OpenAIRE

    2010-01-01

    In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT)-doped tungsten oxide (WO3) thin films by means of the powder mixing and electron beam (E-beam) evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO3 thin film exhibits high sensitivity and selectivity ...

  18. Calculation of gas temperature at the outlet of the combustion chamber and in the air-gas channel of a gas-turbine unit by data of acceptance tests in accordance with ISO

    Science.gov (United States)

    Kostyuk, A. G.; Karpunin, A. P.

    2016-01-01

    This article describes a high accuracy method enabling performance of the calculation of real values of the initial temperature of a gas turbine unit (GTU), i.e., the gas temperature at the outlet of the combustion chamber, in a situation where manufacturers do not disclose this information. The features of the definition of the initial temperature of the GTU according to ISO standards were analyzed. It is noted that the true temperatures for high-temperature GTUs is significantly higher than values determined according to ISO standards. A computational procedure for the determination of gas temperatures in the air-gas channel of the gas turbine and cooling air consumptions over blade rims is proposed. As starting equations, the heat balance equation and the flow mixing equation for the combustion chamber are assumed. Results of acceptance GTU tests according to ISO standards and statistical dependencies of required cooling air consumptions on the gas temperature and the blade metal are also used for calculations. An example of the calculation is given for one of the units. Using a developed computer program, the temperatures in the air-gas channel of certain GTUs are calculated, taking into account their design features. These calculations are performed on the previously published procedure for the detailed calculation of the cooled gas turbine subject to additional losses arising because of the presence of the cooling system. The accuracy of calculations by the computer program is confirmed by conducting verification calculations for the GTU of the Mitsubishi Comp. and comparing results with published data of the company. Calculation data for temperatures were compared with the experimental data and the characteristics of the GTU, and the error of the proposed method is estimated.

  19. Tin Oxide Nanoparticles Produced by Spark Ablation: Synthesis and Gas Sensing Properties

    Directory of Open Access Journals (Sweden)

    Alexey Efimov

    2016-12-01

    Full Text Available The synthesis parameters and results of investigation of gas sensing properties of tin oxide nanoparticles produced by spark ablation are presented. The nanoparticles have sizes below 30 nm and their specific surface area is about 40 m2/g. In order to study the gas sensing properties, a special structure comprising heater, barrier layers and contact pads was utilized. The resistance of the sensor fabricated on the basis of this structure was measured at different concentrations of hydrogen in the air (100–500 ppm and different values of relative humidity (30–80%. At working temperature of 450°C, 100 ppm of hydrogen triggers more than 8-times decrease in the sensor resistance within the time interval of about 1 s. At the same time, the humidity variation does not have pronounced effect on the sensor resistance: less than 30% in the humidity range studied.

  20. Preparation and Gas-Sensing Properties of NdFeO3 Nanocrystalline

    Institute of Scientific and Technical Information of China (English)

    牛新书; 杜卫民; 杜卫平; 蒋凯

    2003-01-01

    With the Nd2O3, Fe(NO3)3·9H2O, nitric acid(1∶1 vloume fraction) for the starting materials, rare earth composite oxide NdFeO3 with the structure of perovskite type was synthesized by sol-gel method in the system of citric acid. Structural characteristics were characterized by XRD and TEM which indicate that the sample is nanocrystallite with uniform grain size distribution and the a verage grain size is about 28 nm. Moreover, the gas sensing properties of the material were tested. The results show that NdFeO3 sensors have high sensitivity, excellent selectivity and quick response and recovery behavior to H2S, hence, this gas sensing material has a better prospects in industrial practice.

  1. Electrical and gas sensing investigations on the sprayed ZnO:Cu thin films

    Science.gov (United States)

    Mhamdi, A.; Alkhalifah, Menea S.; Rajeh, S.; Labidi, A.; Amlouk, M.; Belgacem, S.

    2017-09-01

    The electrical and gas sensing properties of the sprayed Cu doped ZnO thin layers were investigated. The main study is an analysis of the conduction mechanism based on the measurement results of the frequency dispersion of the conductivity at different temperatures performed by impedance spectroscopy. It emerges from this study that the transport mechanism of charge carriers in such thin films is a thermally activated hopping mechanism. This process is confirmed by the obtained values of the maximum barrier height Wm deduced from the study of the frequency power law of the ac conductivity. Otherwise, we have studied the response evolution of ZnO: Cu sensors ethanol versus time, working temperature and relative doping. From the measurement results of gas sensing properties of ZnO:Cu thin film, we find that a good stability and response was observed for a doping of 2%.

  2. Zigzag GaN/Ga2O3 heterogeneous nanowires: Synthesis, optical and gas sensing properties

    Directory of Open Access Journals (Sweden)

    Li-Wei Chang

    2011-09-01

    Full Text Available Zigzag GaN/Ga2O3 heterogeneous nanowires (NWs were fabricated, and the optical properties and NO gas sensing ability of the NWs were investigated. We find that NWs are most effective at 850 °C at a switching process once every 10 min (on/off = 10 min per each with a mixture flow of NH3 and Ar. The red shift of the optical bandgap (0.66 eV is observed from the UV-vis spectrum as the GaN phase forms. The gas sensing characteristics of the developed sensor are significantly replaced to those of other types of NO sensors reported in literature.

  3. Ethanol gas sensing by Zn-doped CdS/CdTe nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Prabhu, M., E-mail: prabhumku@gmail.com; Manikandan, V. S.; Soundararajan, N.; Ramachandran, K. [School of Physics, Madurai Kamaraj University, Madurai – 625 021 (India)

    2016-05-23

    Zn-doped CdS/CdTe nanoparticles (NPs) were synthesized and studied here for gas sensing. The crystallographic properties of the samples were studied by X-ray diffraction (XRD), which shows cubic structure for CdS and CdTe NPs. The three longitudinal optical phonon modes at 298, 595 and 895 cm{sup −1} were obtained from Raman spectrum and this also reveals the cubic structure of CdS NPs. The band gap for Zn-doped CdS/CdTe NPs increased slightly when compared with pure sample. The ethanol gas sensing in CdS/CdTe NPs shows an enhancement on Zn substitution.

  4. The Thermochemical Degradation of Hot Section Materials for Gas Turbine Engines in Alternative-Fuel Combustion Environments

    Science.gov (United States)

    Montalbano, Timothy

    Gas turbine engines remain an integral part of providing the world's propulsion and power generation needs. The continued use of gas turbines requires increased temperature operation to reach higher efficiencies and the implementation of alternative fuels for a lower net-carbon footprint. This necessitates evaluation of the material coatings used to shield the hot section components of gas turbines in these new extreme environments in order to understand how material degradation mechanisms change. Recently, the US Navy has sought to reduce its use of fossil fuels by implementing a blended hydroprocessed renewable diesel (HRD) derived from algae in its fleet. To evaluate the material degradation in this alternative environment, metal alloys are exposed in a simulated combustion environment using this blended fuel or the traditional diesel-like fuel. Evaluation of the metal alloys showed the development of thick, porous scales with a large depletion of aluminum for the blend fuel test. A mechanism linking an increased solubility of the scale to the blend fuel test environment will be discussed. For power generation applications, Integrated Gasification Combined Cycle (IGCC) power plants can provide electricity with 45% efficiency and full carbon capture by using a synthetic gas (syngas) derived from coal, biomass, or another carbon feedstock. However, the combustion of syngas is known to cause high water vapor content levels in the exhaust stream with unknown material consequences. To evaluate the effect of increased humidity, air-plasma sprayed (APS), yttria-stabilized zirconia (YSZ) is thermally aged in an environment with and without humidity. An enhanced destabilization of the parent phase by humid aging is revealed by x-ray diffraction (XRD) and Raman spectroscopy. Microstructural analysis by transmission electron microscopy (TEM) and scanning-TEM (STEM) indicate an enhanced coarsening of the domain structure of the YSZ in the humid environment. The enhanced

  5. Development and Experimental Validation of Large Eddy Simulation Techniques for the Prediction of Combustion-Dynamic Process in Syngas Combustion: Characterization of Autoignition, Flashback, and Flame-Liftoff at Gas-Turbine Relevant Operating Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ihme, Matthias [Univ. of Michigan, Ann Arbor, MI (United States); Driscoll, James [Univ. of Michigan, Ann Arbor, MI (United States)

    2015-08-31

    The objective of this closely coordinated experimental and computational research effort is the development of simulation techniques for the prediction of combustion processes, relevant to the oxidation of syngas and high hydrogen content (HHC) fuels at gas-turbine relevant operating conditions. Specifically, the research goals are (i) the characterization of the sensitivity of syngas ignition processes to hydrodynamic processes and perturbations in temperature and mixture composition in rapid compression machines and ow-reactors and (ii) to conduct comprehensive experimental investigations in a swirl-stabilized gas turbine (GT) combustor under realistic high-pressure operating conditions in order (iii) to obtain fundamental understanding about mechanisms controlling unstable flame regimes in HHC-combustion.

  6. Ionization current sensing; Jonstroem-maetning

    Energy Technology Data Exchange (ETDEWEB)

    Aengeby, Jakob; Goeras, Anders; Nytomt, Jan [Hoerbiger Control Systems AB, Aamaal, (Sweden)

    2012-05-15

    Ion current measurements give information on the combustion in the cylinders of an internal combustion engine in run time, cycle by cycle. Ion sense has been used in gasoline engines for many years for detection of knock and misfire, combustion stability and for air to fuel ratio estimation. However, the use of ion sense in industrial gas engines has been limited, despite the potential of ion sense. The objective with the project is to investigate which combustion process information that can be retrieved using ion sense applied to industrial lean burn engines using pre-chambers for the ignition in which case the spark plug is encapsulated in the pre-chamber. Experiments show that ion current measured in the pre-chamber can successfully be used to retrieve information from the in-cylinder combustion process. It is possible to detect misfire and to some extent knock. It is also possible to optimize the ignition and hence minimize emissions and optimize the performance by using the ion current measured in the pre- chamber. A statistical signal processing approach to use more than one ion current feature in the estimation of combustion parameters was evaluated on a heavy duty gas engine. By using more than one feature the performance of in cylinder air to fuel ratio estimation was improved.

  7. Exploring silver ionic liquids for reaction-based gas sensing on a quartz crystal microbalance.

    Science.gov (United States)

    Li, Hsin-Yi; Hsu, Tzu-Hsuan; Chen, Chien-Yuan; Tseng, Ming-Chung; Chu, Yen-Ho

    2015-09-21

    Reaction-based, sensitive sensing of aldehyde and ketone gases in real time was effectively achieved on QCM chips thin-coated with silver ionic liquids and , respectively. The method platform developed in this work involves straightforward synthesis of functional silver ionic liquids in water, and is label-free and highly chemoselective with superior gas reactivity for and and, most significantly, totally insensitive to moisture.

  8. Palladium Nanoribbon Array for Fast Hydrogen Gas Sensing with Ultrahigh Sensitivity.

    Science.gov (United States)

    Pak, Yusin; Lim, Namsoo; Kumaresan, Yogeenth; Lee, Ryeri; Kim, Kihyeun; Kim, Tae Heon; Kim, Sang-Mook; Kim, Jin Tae; Lee, Heon; Ham, Moon-Ho; Jung, Gun-Young

    2015-11-18

    A lithographically aligned palladium nano-ribbon (Pd-NRB) array with gaps of less than 40 nm is fabricated on a poly(ethylene terephthalate) substrate using the direct metal transfer method. The 200 μm Pd-NRB hydrogen gas sensor exhibits an unprecedented sensitivity of 10(9) % after bending treatment, along with fast sensing behavior (80% response time of 3.6 s and 80% recovery time of 8.7 s) at room temperature.

  9. Combustion of producer gas from gasification of south Sumatera lignite coal using CFD simulation

    National Research Council Canada - National Science Library

    Fajri Vidian; Novia; Andy Suryatra

    2017-01-01

    .... The process was carried out using producer gas from lignite coal gasification of BA 59 was produced by the updraft gasifier which is located on Energy Conversion Laboratory Mechanical Engineering...

  10. Combustion/Emission Species Monitoring Ground and Flight Aeronautical Research Using a Gas Microsensor Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering, Inc. (MEI) and the Ohio State University (OSU) propose to develop high sensitivity, miniaturized and in-situ operated gas sensors for the real...

  11. Combustion/Emission Species Monitoring Ground and Flight Aeronautical Research Using a Gas Microsensor Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this program is to develop a miniaturized and in-situ operated gas microsensor array for the real time monitoring of chemical composition of turbine...

  12. A Technical Review of Compressed Natural Gas as an Alternative Fuel for Internal Combustion Engines

    OpenAIRE

    Semin; Rosli A. Bakar

    2008-01-01

    Natural gas is promising alternative fuel to meet strict engine emission regulations in many countries. Compressed natural gas (CNG) has long been used in stationary engines, but the application of CNG as a transport engines fuel has been considerably advanced over the last decade by the development of lightweight high-pressure storage cylinders. Engine conversion technology is well established and suitable conversion equipment is readily available. For spark ignition engines there are two op...

  13. Combustion LES Software for Improved Emissions Predictions of High Performance Gas Turbine Combustors

    Science.gov (United States)

    2005-09-01

    94 vii 8503/8 ABSTRACT Low emissions of CO, NO,, and unburned hydrocarbons ( UHC ) are a difficult...NOR, UHC , and smoke, are becoming a requirement for today’s and future military gas turbine engines. Advanced, high performance gas turbines will...range, and operating pressure. 2 850318 1. INTRODUCTION Low emissions of pollutants, including CO, NO,,, UHC , and smoke, are becoming a requirement

  14. Performance, Efficiency, and Emissions Characterization of Reciprocating Internal Combustion Engines Fueled with Hydrogen/Natural Gas Blends

    Energy Technology Data Exchange (ETDEWEB)

    Kirby S. Chapman; Amar Patil

    2007-06-30

    Hydrogen is an attractive fuel source not only because it is abundant and renewable but also because it produces almost zero regulated emissions. Internal combustion engines fueled by compressed natural gas (CNG) are operated throughout a variety of industries in a number of mobile and stationary applications. While CNG engines offer many advantages over conventional gasoline and diesel combustion engines, CNG engine performance can be substantially improved in the lean operating region. Lean operation has a number of benefits, the most notable of which is reduced emissions. However, the extremely low flame propagation velocities of CNG greatly restrict the lean operating limits of CNG engines. Hydrogen, however, has a high flame speed and a wide operating limit that extends into the lean region. The addition of hydrogen to a CNG engine makes it a viable and economical method to significantly extend the lean operating limit and thereby improve performance and reduce emissions. Drawbacks of hydrogen as a fuel source, however, include lower power density due to a lower heating value per unit volume as compared to CNG, and susceptibility to pre-ignition and engine knock due to wide flammability limits and low minimum ignition energy. Combining hydrogen with CNG, however, overcomes the drawbacks inherent in each fuel type. Objectives of the current study were to evaluate the feasibility of using blends of hydrogen and natural gas as a fuel for conventional natural gas engines. The experiment and data analysis included evaluation of engine performance, efficiency, and emissions along with detailed in-cylinder measurements of key physical parameters. This provided a detailed knowledge base of the impact of using hydrogen/natural gas blends. A four-stroke, 4.2 L, V-6 naturally aspirated natural gas engine coupled to an eddy current dynamometer was used to measure the impact of hydrogen/natural gas blends on performance, thermodynamic efficiency and exhaust gas emissions

  15. Facile synthesis of porous ZnO microbelts and analysis of their gas-sensing property

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jiarui, E-mail: jrhuang@mail.anhu.edu.cn; Shi, Chengcheng; Fu, Guijun; Sun, Pingping; Wang, Xinyue; Gu, Cuiping, E-mail: cpgu2008@mail.ahnu.edu.cn

    2014-04-01

    Porous ZnO microbelts were achieved using a facile chemical solution method combined with subsequent calcination. The micro-nanostructures were characterized through X-ray diffraction, field emission scanning electron microscopy, thermogravimetric-differential thermal analysis, and Brunauer–Emmett–Teller N{sub 2} adsorption-desorption analyses, among others. The BET surface area of the porous ZnO microbelts was calculated at 23.0 m² g{sup −1}. Furthermore, the gas sensing properties of the as-prepared porous ZnO microbelts were investigated using volatile organic compounds. Compared with ZnO microflowers, the porous ZnO microbelts exhibited higher response with certain organic vapors, such as formaldehyde, acetone, and ethanol. The responses to 100 ppm formaldehyde, acetone, and ethanol were 45.7, 40.6, and 38.4, respectively, at a working temperature of 300 °C. The results showed that the porous ZnO microbelts are highly promising candidates for gas sensing applications. - Highlights: • Zinc glycinate monohydrate microwires were obtained by a chemical solution method. • Porous ZnO microbelts were achieved after calcinations. • The porous ZnO microbelts exhibit superior gas-sensing property.

  16. Effect of gas sensing properties by Sn-Rh codoped ZnO nanosheets

    Science.gov (United States)

    Chen, Ziwei; Lin, Zhidong; Xu, Mengying; Hong, Yuyuan; Li, Na; Fu, Ping; Chen, Ze

    2016-05-01

    The hierarchically porous Sn-Rh codoped ZnO, Sn-doped ZnO and pure ZnO nanosheets have been successfully synthesized through a simple hydrothermal reaction process without any surfactant or template at 180°C. The morphology and composition were carefully characterized by X-ray diffraction, energy dispersive X-ray spectrometer, field emission scanning electronic microscopy and BET. The gas-sensing testing results indicated that the Sn-Rh codoped ZnO nanosheets, with the specific surface area was 26.9 m2/g, exhibited enhanced gas-sensing performance compared with that of pure ZnO and Sn-doped ZnO. The high sensitivity of the sensor based on Sn-Rh codoped ZnO was 149.38 to 100 ppm ethanol and the detection limit was less than 5 ppm (5.8). The response and recovery times were measured to be ˜3 s and ˜10 s when exposed to 100 ppm ethanol at the test temperature of 300°C. The good sensing performance of the Sn-Rh codoped ZnO sensor indicated that hierarchically porous Sn-Rh codoped ZnO could be a promising candidate for highly sensitive gas sensors. [Figure not available: see fulltext.

  17. Ethanol gas sensing properties of Al2O3-doped ZnO thick film resistors

    Indian Academy of Sciences (India)

    D R Patil; L A Patil; D P Amalnerkar

    2007-12-01

    The characterization and ethanol gas sensing properties of pure and doped ZnO thick films were investigated. Thick films of pure zinc oxide were prepared by the screen printing technique. Pure zinc oxide was almost insensitive to ethanol. Thick films of Al2O3 (1 wt%) doped ZnO were observed to be highly sensitive to ethanol vapours at 300°C. Aluminium oxide grains dispersed around ZnO grains would result into the barrier height among the grains. Upon exposure of ethanol vapours, the barrier height would decrease greatly leading to drastic increase in conductance. It is reported that the surface misfits, calcination temperature and operating temperature can affect the microstructure and gas sensing performance of the sensor. The efforts are, therefore, made to create surface misfits by doping Al2O3 into zinc oxide and to study the sensing performance. The quick response and fast recovery are the main features of this sensor. The effects of microstructure and additive concentration on the gas response, selectivity, response time and recovery time of the sensor in the presence of ethanol vapours were studied and discussed.

  18. Development of a pilot fluidized bed combustion to NOx reduction using natural gas: characterization and dimensioning; Desenvolvimento de um combustor piloto a leito fluidizado para reducao de NOx usando gas natural: caracterizacao e dimensionamento

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Douglas A.; Lucena, Sergio [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2004-07-01

    At the present time, the operation of combustion systems and the design of combustors continue being important problems in the Engineering, and don't involve just the size increase of combustors, but also changes of characteristics in the details of projects. The combustors applications are directly related to the needs, like: material transformation for heating, drying or incineration; and all have the inconvenience of emanating of pollutant gaseous (such like NOx). In combustion systems of gases, NOx is basically created in the reaction between nitrogen and oxygen to high temperatures ({approx} 1200 deg C). Below such conditions, the contribution of thermal NOx is recognisably small. The efficient reduction, safe control and economical elimination of pollutant emissions in the systems of burning are the main focuses of environmental legislation and concern to several industrialized countries, besides Brazil. Furthermore, in appeal at the Environmental Laws and at the rising consumption of combustible gases (Natural Gas), new technologies more attractive and economically viable have been studied, for example the combustion systems in fluidized bed. In this kind of system is possible to obtain high combustion efficiency at low temperatures ({approx} 900 deg C) with NOx reduction. In this work is intended of characterizing and dimensioning an industrial fluidized bed combustor that uses Natural Gas like feedstock in the combustion system, with smaller amounts of emitted NOx. (author)

  19. Synergistic improvement of gas sensing performance by micro-gravimetrically extracted kinetic/thermodynamic parameters

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Shuanbao; Xu, Pengcheng; Yu, Haitao; Cheng, Zhenxing; Li, Xinxin, E-mail: xxli@mail.sim.ac.cn

    2015-03-10

    Highlights: • Sensing material can be comprehensively optimized by using gravimetric cantilever. • Kinetic-thermodynamic model parameters are quantitatively extracted by experiment • Sensing-material performance is synergistically optimized by extracted parameters. - Abstract: A novel method is explored for comprehensive design/optimization of organophosphorus sensing material, which is loaded on mass-type microcantilever sensor. Conventionally, by directly observing the gas sensing response, it is difficult to build quantitative relationship with the intrinsic structure of the material. To break through this difficulty, resonant cantilever is employed as gravimetric tool to implement molecule adsorption experiment. Based on the sensing data, key kinetic/thermodynamic parameters of the material to the molecule, including adsorption heat −ΔH°, adsorption/desorption rate constants K{sub a} and K{sub d}, active-site number per unit mass N′ and surface coverage θ, can be quantitatively extracted according to physical–chemistry theories. With gaseous DMMP (simulant of organophosphorus agents) as sensing target, the optimization route for three sensing materials is successfully demonstrated. Firstly, a hyper-branched polymer is evaluated. Though suffering low sensitivity due to insufficient N′, the bis(4-hydroxyphenyl)-hexafluoropropane (BHPF) sensing-group exhibits satisfactory reproducibility due to appropriate −ΔH°. To achieve more sensing-sites, KIT-5 mesoporous-silica with higher surface-area is assessed, resulting in good sensitivity but too high −ΔH° that brings poor repeatability. After comprehensive consideration, the confirmed BHPF sensing-group is grafted on the KIT-5 carrier to form an optimized DMMP sensing nanomaterial. Experimental results indicate that, featuring appropriate kinetic/thermodynamic parameters of −ΔH°, K{sub a}, K{sub d}, N′ and θ, the BHPF-functionalized KIT-5 mesoporous silica exhibits synergistic

  20. A novel field measurement method for determining fine particle and gas emissions from residential wood combustion

    Science.gov (United States)

    Tissari, Jarkko; Hytönen, Kati; Lyyränen, Jussi; Jokiniemi, Jorma

    Emission data from residential wood combustion are usually obtained on test stands in the laboratory but these measurements do not correspond to the operational conditions in the field because of the technological boundary conditions (e.g. testing protocol, environmental and draught conditions). The field measurements take into account the habitual practice of the operators and provide the more reliable results needed for emission inventories. In this study, a workable and compact method for measuring emissions from residential wood combustion in winter conditions was developed. The emissions for fine particle, gaseous and PAH compounds as well as particle composition in real operational conditions were measured from seven different appliances. The measurement technique worked well and was evidently suitable for winter conditions. It was easy and fast to use, and no construction scaffold was needed. The dilution of the sample with the combination of a porous tube diluter and an ejector diluter was well suited to field measurement. The results indicate that the emissions of total volatile organic carbon (TVOC) (17 g kg -1 (of dry wood burned)), carbon monoxide (CO) (120 g kg -1) and fine particle mass (PM 1) (2.7 g kg -1) from the sauna stove were higher than in the other measured appliances. In the masonry heaters, baking oven and stove, the emissions were 2.9-9 g kg -1 TVOC, 28-68 g kg -1 CO and 0.6-1.6 g kg -1 PM 1. The emission of 12 PAHs (PAH 12) from the sauna stove was 164 mg kg -1 and consisted mainly of PAHs with four benzene rings in their structure. PAH 12 emission from other appliances was, on average, 21 mg kg -1 and was dominated by 2-ring PAHs. These results indicate that despite the non-optimal operational practices in the field, the emissions did not differ markedly from the laboratory measurements.