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Sample records for vapour compression chiller

  1. Experimental Investigation of a Mechanical Vapour Compression Chiller at Elevated Chilled Water Temperatures

    KAUST Repository

    Thu, Kyaw

    2017-05-18

    The performance of a Mechanical Vapour Compression (MVC) chiller is experimentally investigated under operating conditions suitable for sensible cooling. With the emergence of the energy efficient dehumidification systems, it is possible to decouple the latent load from the MVC chillers which can be operated at higher chilled water temperature for handling sensible cooling load. In this article, the performance of the chiller is evaluated at the elevated chilled water outlet temperatures (7 – 17° C) at various coolant temperatures (28 – 32° C) and flow rates (ΔT = 4 and 5° C) for both full- and part-load conditions. Keeping the performance at the AHRI standard as the baseline condition, the efficacy of the chiller in terms of compression ratio, cooling capacity and COP at aforementioned conditions is quantified experimentally. It is observed that for each one-degree Celsius increase in the chilled water temperature, the COP of the chiller improves by about 3.5% whilst the cooling capacity improvement is about 4%. For operation at 17° C chilled water outlet temperature, the improvements in COP and cooling capacity are between 37 – 40% and 40 – 45%, respectively, compared to the performance at the AHRI standards. The performance of the MVC chiller at the abovementioned operation conditions is mapped on the chiller performance characteristic chart.

  2. Experimental Investigation of a Mechanical Vapour Compression Chiller at Elevated Chilled Water Temperatures

    KAUST Repository

    Thu, Kyaw; Saththasivam, Jayaprakash; Saha, Bidyut Baran; Chua, Kian Jon; Srinivasa Murthy, S.; Ng, Kim Choon

    2017-01-01

    The performance of a Mechanical Vapour Compression (MVC) chiller is experimentally investigated under operating conditions suitable for sensible cooling. With the emergence of the energy efficient dehumidification systems, it is possible to decouple the latent load from the MVC chillers which can be operated at higher chilled water temperature for handling sensible cooling load. In this article, the performance of the chiller is evaluated at the elevated chilled water outlet temperatures (7 – 17° C) at various coolant temperatures (28 – 32° C) and flow rates (ΔT = 4 and 5° C) for both full- and part-load conditions. Keeping the performance at the AHRI standard as the baseline condition, the efficacy of the chiller in terms of compression ratio, cooling capacity and COP at aforementioned conditions is quantified experimentally. It is observed that for each one-degree Celsius increase in the chilled water temperature, the COP of the chiller improves by about 3.5% whilst the cooling capacity improvement is about 4%. For operation at 17° C chilled water outlet temperature, the improvements in COP and cooling capacity are between 37 – 40% and 40 – 45%, respectively, compared to the performance at the AHRI standards. The performance of the MVC chiller at the abovementioned operation conditions is mapped on the chiller performance characteristic chart.

  3. Experimental investigation of integrated refrigeration system (IRS) with gas engine, compression chiller and absorption chiller

    International Nuclear Information System (INIS)

    Sun, Z.G.

    2008-01-01

    An integrated refrigeration system (IRS) with a gas engine, a vapor-compression chiller and an absorption chiller is set up and tested. The vapor-compression refrigeration cycle is operated directly by the gas engine. The waste heat from the gas engine operates the absorption refrigeration cycle, which provides additional cooling. The performance of the IRS is described. The cooling capacity of the IRS is about 596 kW, and primary energy ratio (PER) reaches 1.84 at air-conditioning rated conditions. The refrigerating capacity of the prototype increased and PER of prototype decreased with the increase of the gas engine speed. The gas engine speed was preferably regulated at part load condition in order to operate the prototype at high-energy efficiency. The refrigerating capacity and PER of the prototype increased with the increase of the outlet temperature of chilled water or the decrease of the inlet temperature of cooling water. The integrated refrigeration chiller in this work saves running costs as compared to the conventional refrigeration system by using the waste heat

  4. Scope-oriented thermoeconomic analysis of energy systems. Part I: Looking for a non-postulated cost accounting for the dissipative devices of a vapour compression chiller. Is it feasible?

    Energy Technology Data Exchange (ETDEWEB)

    Piacentino, Antonio; Cardona, Fabio [DREAM - Department of Energy and Environmental Researches, University of Palermo, Viale delle Scienze, 90128 Palermo (Italy)

    2010-03-15

    The authors of the main thermoeconomic methodologies developed in the last two decades have recently focused their efforts on the analysis of dissipative devices, i.e. those components whose productive purpose is neither intuitive nor easy to define. Coherent and unanimously accepted cost structures have been identified for dissipative components, while ambiguities still exist as concerns the cost allocation principles to be adopted. Being this aspect evidently cost-influencing, accurate analyses focused on the subjectivity of results are needed. This paper is structured in two parts. In the Part I an in-depth study of some critical issues arising from the thermoeconomic analysis of a 1.5 MW{sub c} industrial chiller is presented. The attention is focused on the role of the condenser and the throttling valve (considered as a limit condition for an expander with very low isentropic efficiency); marginal analyses performed on the condensation pressure and the isentropic efficiency of the expander provided elements to assess the rational of the cost allocation principles. Attempting to refugee any cost allocation criterion based on postulates, the concept of Scope is identified as a possible non-arbitrary basis for cost allocation in dissipative devices; consequently, a new topology is defined, abandoning the conventional classification between dissipative and productive units, toward a new distinction between Product Makers and Product Takers functions. The proposed approach is applied to the cost accounting of the examined chiller, revealing inadequate and less explicative than the conventional thermoeconomic approaches due to its ''intrinsically differential'' nature. In the Part II of this paper the proposed approach will be applied to an Optimization problem, revealing very flexible and insightful. (author)

  5. Analysis of a combined Rankine-vapour-compression refrigeration cycle

    International Nuclear Information System (INIS)

    Aphornratana, Satha; Sriveerakul, Thanarath

    2010-01-01

    This paper describes a theoretical analysis of a heat-powered refrigeration cycle, a combined Rankine-vapour-compression refrigeration cycle. This refrigeration cycle combines an Organic Rankine Cycle and a vapour-compression cycle. The cycle can be powered by low grade thermal energy as low as 60 deg. C and can produce cooling temperature as low as -10 deg. C. In the analysis, two combined Rankine-vapour-compression refrigeration cycles were investigated: the system with R22 and the system with R134a. Calculated COP values between 0.1 and 0.6 of both the systems were found.

  6. Comparative study of air conditioning systems with vapor compression chillers using the concept of green buildings

    Directory of Open Access Journals (Sweden)

    Gutenberg da Silva Pereira

    2015-10-01

    Full Text Available This paper sets out to compare two different cooling systems that use vapor compression chillers for air conditioning environments. It was proposed to compare different operations in isolated and combined action operations. These operations are evaluated in the concepts of green buildings. A mathematical model was developed based on the principles of mass and energy conservation and complemented by various functions so as to determine the thermophysical properties and efficiencies of the compressors. The equations of the model were solved by the EES (Engineering Equation Solver program. The model evaluates the influence of the main HVAC operating parameters of the chilled water system when operating under three different configurations. The results showed that the system with a differentiated compression presents a COP equal to that of the system with screw chillers in the range  0-300 RTs, and a COP hat is on average 9% higher in the range 400-800 RTs.

  7. Scheduling of Multiple Chillers in Trigeneration Plants

    Directory of Open Access Journals (Sweden)

    Chris Underwood

    2015-10-01

    Full Text Available The scheduling of both absorption cycle and vapour compression cycle chillers in trigeneration plants is investigated in this work. Many trigeneration plants use absorption cycle chillers only but there are potential performance advantages to be gained by using a combination of absorption and compression chillers especially in situations where the building electrical demand to be met by the combined heat and power (CHP plant is variable. Simulation models of both types of chillers are developed together with a simple model of a variable-capacity CHP engine developed by curve-fitting to supplier’s data. The models are linked to form an optimisation problem in which the contribution of both chiller types is determined at a maximum value of operating cost (or carbon emission saving. Results show that an optimum operating condition arises at moderately high air conditioning demands and moderately low power demand when the air conditioning demand is shared between both chillers, all recovered heat is utilised, and the contribution arising from the compression chiller results in an increase in CHP power generation and, hence, engine efficiency.

  8. The mechanical vapour compression process applied to seawater desalination

    International Nuclear Information System (INIS)

    Murat, F.; Tabourier, B.

    1984-01-01

    The authors present the mechanical vapour compression process applied to sea water desalination. As an example, the paper presents the largest unit so far constructed by SIDEM using this process : a 1,500 m3/day unit installed in the Nuclear Power Plant of Flamanville in France which supplies a high quality process water to that plant. The authors outline the advantages of this process and present also the serie of mechanical vapour compression unit that SIDEM has developed in a size range in between 25 m3/day and 2,500 m3/day

  9. Refrigerants for Vapour Compression Refrigeration Systems

    Indian Academy of Sciences (India)

    c) Low compression ratio to give high volumetric efficiency and low power ... The normal boiling point5 is also a good indicator of the critical temperature since .... than a few minutes during maintenance and service activities. Freezing point of ...

  10. Desalination using spray tower and vapour compression refrigeration system

    International Nuclear Information System (INIS)

    Sathish Kumar, S.; Mani, A.

    2006-01-01

    A desalination system using a spray tower and Vapour Compression Refrigeration (VCR) system is proposed for obtaining fresh water from brackish water. In the spray tower, simultaneous heat and mass transfer take place between the brackish water and air, which results in the evaporation of the brackish water and humidification of the air. Fresh water is obtained from the humidified air by condensing the water vapour using a VCR system. Parametric studies were carried out to study the effect of various operational parameters on the fresh water production rate. (author)

  11. A study of the thermodynamic performance and CO2 emissions of a vapour compression bio-trigeneration system

    International Nuclear Information System (INIS)

    Parise, Jose A.R.; Castillo Martinez, Luis C.; Pitanga Marques, Rui; Betancourt Mena, Jesus; Vargas, Jose V.C.

    2011-01-01

    A trigeneration system (simultaneous production of heating, cooling and electricity) using a heat engine and a vapour compression chiller, running on biofuel, is studied. A system configuration, capable of meeting the three energy demands in a realistic situation, was devised. It consisted of a compression ignition internal combustion engine driving an electric generator, an electrically driven vapour compression heat pump and a peak boiler. Part of the heating demand was met by recovering waste heat from the engine and the heat pump condenser, thus reducing the overall fuel consumption. New criteria parameters, based on the relative magnitudes of the three energy demands, were defined to evaluate thermal performance and CO 2 emissions. A comparative analysis between the biofuel trigeneration and conventional fossil fuel with no waste heat recovery was carried out, showing that, depending on the relative values of energy demands and on component characteristics, significant reduction on primary energy consumption (up to 50%) and on CO 2 emissions (up to 5% of the original emissions) can be attained with the biofuel-trigeneration combination.

  12. Improvement of a thermoelectric and vapour compression hybrid refrigerator

    International Nuclear Information System (INIS)

    Astrain, D.; Martínez, A.; Rodríguez, A.

    2012-01-01

    This paper presents the improvement in the performance of a domestic hybrid refrigerator that combines vapour compression technology for the cooler and freezer compartments, and thermoelectric technology for a new compartment. The heat emitted by the Peltier modules is discharged into the freezer compartment, forming a cascade refrigeration system. This configuration leads to a significant improvement in the coefficient of operation. Thus, the electric power consumption of the modules and the refrigerator decreases by 95% and 20% respectively, with respect to those attained with a cascade refrigeration system connected with the cooler compartment. The optimization process is based on a computational model that simulates the behaviour of the whole refrigerator. Two prototypes have been built and tested. Experimental results indicate that the temperature of the new compartment is easily set up at any value between 0 and −4 °C, the oscillation of this temperature is always lower than 0.4 °C, and the electric power consumption is low enough to include this hybrid refrigerator into energy efficiency class A, according European rules and regulations. - Highlights: ► Optimization of a vapour compression and thermoelectric hybrid refrigerator. ► Two prototypes built and tested. Computational model for the whole refrigerator. ► Electric power consumption of the modules and the refrigerator 95% and 20% lower. ► New compartment refrigerated with thermoelectric technology. ► Inner temperature adjustable from 0 to −4 °C. Oscillations lower than ±0.2 °C.

  13. Energy Efficiency Evaluation and Economic Feasibility Analysis of a Geothermal Heating and Cooling System with a Vapor-Compression Chiller System

    OpenAIRE

    Imal, Muharrem; Yılmaz, Koray; Pınarbaşı, Ahmet

    2015-01-01

    Increasing attention has been given to energy utilization in Turkey. In this report, we present an energy efficiency evaluation and economic feasibility analysis of a geothermal heating and cooling system (GSHP) and a mechanical compression water chiller system (ACHP) to improve the energy utilization efficiency and reduce the primary energy demand for industrial use. Analyses of a mechanical water chiller unit, GSW 180, and geothermal heating and cooling system, EAR 431 SK, were conducted in ...

  14. Vapour and air bubble collapse analysis in viscous compressible water

    Directory of Open Access Journals (Sweden)

    Gil Bazanini

    2001-01-01

    Full Text Available Numerical simulations of the collapse of bubbles (or cavities are shown, using the finite difference method, taking into account the compressibility of the liquid, expected to occur in the final stages of the collapse process. Results are compared with experimental and theoretical data for incompressible liquids, to see the influence of the compressibility of the water in the bubble collapse. Pressure fields values are calculated in an area of 800 x 800 mm, for the case of one bubble under the hypothesis of spherical symmetry. Results are shown as radius versus time curves for the collapse (to compare collapse times, and pressure curves in the plane, for pressure fields. Such calculations are new because of their general point of view, since the existing works do not take into account the existence of vapour in the bubble, neither show the pressure fields seen here. It is also expected to see the influence of the compressibility of the water in the collapse time, and in the pressure field, when comparing pressure values.

  15. A dynamic model of a photovoltaic vapour compression system

    International Nuclear Information System (INIS)

    Renno, C.

    2009-01-01

    A dynamic simulation of a photovoltaic vapour compression system is presented in this paper. In particular, there are several options to convert solar energy into refrigeration effect such as the absorption cycle, the thermo-mechanical refrigeration systems, the regenerative desiccant process or the steam jet system. This effect can also be produced by a conventional vapor compression cycle in which the compressor is driven by an electric motor supplied by means of photovoltaic cells. It is also possible to produce the cooling effect adopting the thermoelectric refrigeration, with electricity supplied by means of photovoltaic cells. Absorption and solar mechanical systems are necessarily larger and require extensive plumbing and electrical connections. The dynamic model allows to obtain some characteristic temperatures of the photovoltaic system and the energy consumptions with and without load perturbations. This model results a useful tool to study the dynamic working, for example, of photovoltaic refrigerators used in rural areas and remote islands, for their simple structure and low costs, to preserve foodstuffs, vaccines and other life saving medicines. (author)

  16. A review on the recent development of solar absorption and vapour compression based hybrid air conditioning with low temperature storage

    Directory of Open Access Journals (Sweden)

    Noor D. N.

    2016-01-01

    Full Text Available Conventional air conditioners or vapour compression systems are main contributors to energy consumption in modern buildings. There are common environmental issues emanating from vapour compression system such as greenhouse gas emission and heat wastage. These problems can be reduced by adaptation of solar energy components to vapour compression system. However, intermittence input of daily solar radiation was the main issue of solar energy system. This paper presents the recent studies on hybrid air conditioning system. In addition, the basic vapour compression system and components involved in the solar air conditioning system are discussed. Introduction of low temperature storage can be an interactive solution and improved economically which portray different modes of operating strategies. Yet, very few studies have examined on optimal operating strategies of the hybrid system. Finally, the findings of this review will help suggest optimization of solar absorption and vapour compression based hybrid air conditioning system for future work while considering both economic and environmental factors.

  17. Energy Efficiency Evaluation and Economic Feasibility Analysis of a Geothermal Heating and Cooling System with a Vapor-Compression Chiller System

    Directory of Open Access Journals (Sweden)

    Muharrem Imal

    2015-09-01

    Full Text Available Increasing attention has been given to energy utilization in Turkey. In this report, we present an energy efficiency evaluation and economic feasibility analysis of a geothermal heating and cooling system (GSHP and a mechanical compression water chiller system (ACHP to improve the energy utilization efficiency and reduce the primary energy demand for industrial use. Analyses of a mechanical water chiller unit, GSW 180, and geothermal heating and cooling system, EAR 431 SK, were conducted in experimental working areas of the office buildings in a cigarette factory in Mersin, Turkey. The heating and cooling loads of the cigarette factory building were calculated, and actual thermal data were collected and analyzed. To calculate these loads, the cooling load temperature difference method was used. It was concluded that the geothermal heating and cooling system was more useful and productive and provides substantial economic benefits.

  18. Some safety aspects of CO2 vapour compression systems

    Energy Technology Data Exchange (ETDEWEB)

    Pettersen, J. [Department of Refrigeration and Air Conditioning, Norwegian University of Science and Technology NTNU, Trondheim (Norway); Hafner, A.; Braanaas, M. [SINTEF Energy Research, Refrigeration and Air Conditioning, Trondheim (Norway)

    2000-11-01

    Since CO2 is a non-toxic and non-flammable refrigerant, the major safety issues for CO2 systems are related to the high operating pressure. In case of a component rupture, the explosion energy (stored energy) may characterise the extent of potential damage.The explosion energy can be estimated based on component (refrigerant-side) volumes, pressures and refrigerant property data. The explosion (stored) energies of baseline systems and CO2 systems are calculated and compared. Results show that the explosion energies are not as different as the large difference in pressure would indicate. It has been suggested that a Boiling Liquid Expanding Vapour Explosion (BLEVE) may occur when a vessel containing pressurised liquid or supercritical fluid is rapidly depressurised, e.g. due to a crack or a rupture. The overpressure from a BLEVE may be high enough to rupture the whole vessel, with a resulting blast wave and risk of flying fragments. Some tests on CO2 have been conducted at varying initial conditions and liquid fill levels, and with varying vent areas. No significant overpressure peaks above the initial pressure has been observed in the current test programme. 19 refs.

  19. Thermodynamic study of multi-effect thermal vapour-compression desalination systems

    International Nuclear Information System (INIS)

    Samaké, Oumar; Galanis, Nicolas; Sorin, Mikhail

    2014-01-01

    The parametric analysis of a multi-effect-evaporation (MEE) desalination system combined with a thermal-vapour-compression (TVC) process activated by a gaseous stream of specified flowrate and temperature was performed based on the principles of classical (1st and 2nd laws) and finite-size thermodynamics. The MEE subsystem was treated as a black box and therefore the results are valid for any combination of physical characteristics and internal operational conditions of this subsystem. They show the effects of four design variables (the motive fluid pressure and the compression ratio of the ejector, the condenser temperature pinch and the ratio of rejected to supplied seawater) on significant operating quantities and performance indicators such as: energy supplied by the heat source; motive fluid flowrate; flowrates of the supplied seawater and produced potable water; specific heat consumption; thermal conductance of the vapour generator and the condenser; exergy destruction by the MEE, the ejector and the vapour generator. Based on the obtained results recommendations are formulated for the optimal choice of values for the four design variables. - Highlights: • Model of a MEE-TVC desalination system independent of MEE characteristics. • Parametric study based on classical (1st and 2nd law) and finite-size thermodynamics. • Effect of 4 design parameters on operating conditions and performance indicators. • Recommended values for the design parameters

  20. Parametric analysis of a combined dew point evaporative-vapour compression based air conditioning system

    Directory of Open Access Journals (Sweden)

    Shailendra Singh Chauhan

    2016-09-01

    Full Text Available A dew point evaporative-vapour compression based combined air conditioning system for providing good human comfort conditions at a low cost has been proposed in this paper. The proposed system has been parametrically analysed for a wide range of ambient temperatures and specific humidity under some reasonable assumptions. The proposed system has also been compared from the conventional vapour compression air conditioner on the basis of cooling load on the cooling coil working on 100% fresh air assumption. The saving of cooling load on the coil was found to be maximum with a value of 60.93% at 46 °C and 6 g/kg specific humidity, while it was negative for very high humidity of ambient air, which indicates that proposed system is applicable for dry and moderate humid conditions but not for very humid conditions. The system is working well with an average net monthly power saving of 192.31 kW h for hot and dry conditions and 124.38 kW h for hot and moderate humid conditions. Therefore it could be a better alternative for dry and moderate humid climate with a payback period of 7.2 years.

  1. Design and Simulation of a Vapour Compression Refrigeration System Using Phase Change Material

    Directory of Open Access Journals (Sweden)

    Siddharth Raju

    2018-01-01

    Full Text Available The paper details the design and simulation of a solar powered vapour compression refrigeration system. The effect of a phase change material, in this case ice, on a vapour compression refrigeration system powered by solar panels is discussed. The battery and solar panels were sized to allow the system to function as an autonomous unit for a minimum of 12 hours. It was concluded that the presence of a phase change material in the refrigeration system caused a considerable increase in both the on and off time of the compressor. The ratio by which the on time increased was greater than the ratio by which the off time was increased. There was a 219% increase in the on time, a 139% increase in the compressor off time and a 3.5% increase in compressor work accompanied by a 5.5% reduction in COP. Thus, under conditions where there is enough load in the system to cause the initial on and off times of the compressor to be comparable, the presence of a phase change material may result in a greater on period than an off period for the compressor.

  2. Influence of special attributes of zeotropic refrigerant mixtures on design and operation of vapour compression refrigeration and heat pump systems

    International Nuclear Information System (INIS)

    Rajapaksha, Leelananda

    2007-01-01

    The use of zeotropic refrigerant mixtures introduces a number of novel issues that affect the established design and operational practices of vapour compression systems used in refrigeration, air conditioning and heat pump applications. Two attributes; composition shift and temperature glide, associated with the phase changing process of zeotropic mixtures are the primary phenomena that bring in these issues. However, relevant researches are uncovering ways how careful system designs and selection of operational parameters allow improving the energy efficiency and the capacity of vapour compression refrigeration systems. Most of these concepts exploit the presence of composition shift and temperature glide. This paper qualitatively discusses how the mixture attributes influence the established heat exchanger design practices, performance and operation of conventional vapour compression systems. How the temperature glide and composition shift can be incorporated to improve the system performance and the efficiency are also discussed

  3. Prediction of Chiller Power Consumption: An Entropy Generation Approach

    KAUST Repository

    Saththasivam, Jayaprakash

    2016-06-21

    Irreversibilities in each component of vapor compression chillers contribute to additional power consumption in chillers. In this study, chiller power consumption was predicted by computing the Carnot reversible work and entropy generated in every component of the chiller. Thermodynamic properties namely enthalpy and entropy of the entire refrigerant cycle were obtained by measuring the pressure and temperature at the inlet and outlet of each primary component of a 15kW R22 water cooled scroll chiller. Entropy generation of each component was then calculated using the First and Second Laws of Thermodynamics. Good correlation was found between the measured and computed chiller power consumption. This irreversibility analysis can be also effectively used as a performance monitoring tool in vapor compression chillers as higher entropy generation is anticipated during faulty operations.

  4. Roughness and compressive strength of FDM 3D printed specimens affected by acetone vapour treatment

    Science.gov (United States)

    Beniak, Juraj; Križan, Peter; Šooš, Ľubomír; Matúš, Miloš

    2018-01-01

    Rapid Prototyping technologies are the fastest growing technologies in the manufacturing of components and parts. There are many techniques which can be used with different materials and different purposes of produced part. Gradually, Rapid Prototyping systems have grown into Additive Manufacturing, because technology expansion brings faster production, improved manufactured components, and expanded palette of used materials. So now this techniques are also used for regular production of special parts, where is usual change of part design, where is necessary to produce variety of different designs and shapes. The following article deals with Fused Deposition Modelling (FDM) technology, the core of which is the manufacture models and components from thermoplastic polymers by deposition single fibres of semi-molten plastic material layer by layer. The article focuses on the results of research for testing of manufactured specimens by FDM technology. Components are modified by acetone vapour for surface smoothing. The purpose is to point out how the additional specimen treatment influence the strength properties. Presented paper shows realized experiments and measurements of compressive force on specimens and surface roughness which are influenced by acetone vapour treatment.

  5. Modelling and optimization of seawater desalination process using mechanical vapour compression

    Directory of Open Access Journals (Sweden)

    V.P. Kravchenko

    2016-09-01

    Full Text Available In the conditions of global climate changes shortage of fresh water becomes an urgent problem for an increasing number of the countries. One of the most perspective technologies of a desalting of sea water is the mechanical vapour compression (MVC providing low energy consumption due to the principle of a heat pump. Aim: The aim of this research is to identify the reserves of efficiency increasing of the desalination systems based on mechanical vapour compression by optimization of the scheme and parameters of installations with MVC. Materials and Methods: The new type of desalination installation is offered which main element is the heat exchanger of the latent heat. Sea water after preliminary heating in heat exchangers comes to the evaporator-condenser where receives the main amount of heat from the condensed steam. A part of sea water evaporates, and the strong solution of salt (brine goes out of the evaporator, and after cooling is dumped back in the sea. The formed steam is compressed by the compressor and comes to the condenser. An essential singularity of this scheme is that condensation happens at higher temperature, than evaporation. Thanks to this the heat, which is comes out at devaporation, is used for evaporation of sea water. Thereby, in this class of desalination installations the principle of a heat pump is implemented. Results: For achievement of a goal the following tasks were solved: the mathematical model of installations with MVC is modified and supplemented; the scheme of heat exchangers switching is modified; influence of design data of desalination installation on the cost of an inventory and the electric power is investigated. The detailed analysis of the main schemes of installation and mathematical model allowed defining ways of decrease in energy consumption and the possible merit value. Influence of two key parameters - a specific power of the compressor and a specific surface area of the evaporator-condenser - on a

  6. Comparative investigation of thermoelectric air-conditioners versus vapour compression and absorption air-conditioners

    International Nuclear Information System (INIS)

    Riffat, S.B.; Qiu Guoquan

    2004-01-01

    This paper compares the performance of three types of domestic air-conditioners, namely the vapour compression air-conditioner (VCAC), the absorption air-conditioner (AAC) and the thermoelectric air-conditioner (TEAC). The basic cycles of the three types of air-conditioning systems are described and methods to calculate their coefficients of performance are presented. General specification data for each type of air-conditioner are given, and performance characteristics are presented. The comparison shows that although VCACs have the advantages of high COP and low purchase price, use of these systems will be phased out due to their contribution to the greenhouse effect and depletion of the ozone layer. AACs are generally bulky, complex and expensive but operate on thermal energy, so their operational consumption is low. TEACs are environmental friendly, simple and reliable but still very expensive at present. Their low COP is an additional factor limiting their application for domestic cooling. TEACs however, have a large potential market as air-conditioners for small enclosures, such as cars and submarine cabins, where the power consumption would be low, or safety and reliability would be important

  7. Ammonia-lithium nitrate absorption chiller with an integrated low-pressure compression booster cycle for low driving temperatures

    International Nuclear Information System (INIS)

    Ventas, R.; Lecuona, A.; Zacarias, A.; Venegas, M.

    2010-01-01

    Single-effect absorption refrigeration hybridized with mechanical vapor compression in a vapor circuit is known as the absorption cycle with an integrated booster compressor. In this study, the compressor is located between the evaporator and the absorber. This paper presents a numerical model of this cycle with ammonia-lithium nitrate solution as the working pair. It is based on UA-ΔT lm models for separate regions of plate-type heat exchangers. The results are offered as a function of external circuit flow parameters. Different pressure ratios of the compressor were tested for a wide range of hot water driving temperatures (55-95 deg. C), showing that low values are more beneficial. This cycle allows for working at lower driving temperatures than the single-effect cycle, with low electricity consumption. At the same driving temperature, the capacity is augmented with an increased compressor pressure ratio, thus allowing for demand matching of the cooling. This cycle, operating with hot water at 67 deg. C with a pressure ratio of 2.0, has the capacity of a single-effect absorption cycle at 94 deg. C. The electrical COP was found to be higher than that in an ammonia vapor compression cycle for comprehensive working conditions.

  8. Zero-ODP Refrigerants for Low Tonnage Centrifugal Chiller Systems

    National Research Council Canada - National Science Library

    Gui, Fulin

    1996-01-01

    ..., HFC-236cb, HFC-236fa, HFC-245cb, and HFC-254cb, for centrifugal chiller applications. We took into account the thermodynamic properties of the refrigerant and aerodynamic properties of the impeller compression process to this evaluation...

  9. Exergetic and thermodynamic comparison of R12 and R134a as vapour compression refrigeration working fluids

    Energy Technology Data Exchange (ETDEWEB)

    De Rossi, Filippo; Mastrullo, Rita; Mazzei, Pietro [Naples Univ. (Italy)

    1993-05-01

    A software package for both the computation of thermodynamic properties and the analysis of the usual vapour compression plant schemes is a useful tool for air conditioning and refrigeration researchers and manufacturers. At present, it could make an important contribution to the search for CFC substitutes; in fact, comparisons between two or more working fluids could be accomplished more easily. A program created by the authors is presented by means of some demonstrative diagrams referring to a comparison between the ''ozone killer'' R12 and its substitute R134a. An R134a exergy-enthalpy chart is also provided. (Author)

  10. Compressibility and specific heats of heavier condensed rare gases near the liquid-vapour critical point

    International Nuclear Information System (INIS)

    March, N.H.

    2003-08-01

    Sarkisov (J. Chem. Phys. 119, 373, 2003) has recently discussed the structural behaviour of a simple fluid near the liquid-vapour critical point. His work, already compared with computer simulation studies, is here brought into direct contact for the heavier condensed rare gases Ar, Kr and Xe with (a) experiment and (b) earlier theoretical investigations. Directions for future studies then emerge. (author)

  11. Experimental and numerical study of two-phase flows at the inlet of evaporators in vapour compression cycles

    International Nuclear Information System (INIS)

    Ahmad, M.

    2007-09-01

    Maldistribution of liquid-vapour two phase flows causes a significant decrease of the thermal and hydraulic performance of evaporators in thermodynamic vapour compression cycles. A first experimental installation was used to visualize the two phase flow evolution between the expansion valve and the evaporator inlet. A second experimental set-up simulating a compact heat exchanger has been designed to identify the functional and geometrical parameters creating the best distribution of the two phases in the different channels. An analysis and a comprehension of the relation between the geometrical and functional parameters with the flow pattern inside the header and the two phase distribution, has been established. A numerical simulations of a stratified flow and a stratified jet flow have been carried out using two CFD codes: FLUENT and NEPTUNE. In the case of a fragmented jet configuration, a global definition of the interfacial area concentration for a separated phases and dispersed phases flow has been established and a model calculating the fragmented mass fraction has been developed. (author)

  12. A numerical model for the dynamic simulation of a recirculation single-effect absorption chiller

    International Nuclear Information System (INIS)

    Zinet, Matthieu; Rulliere, Romuald; Haberschill, Philippe

    2012-01-01

    Highlights: ► Dynamic simulation of a new recirculation single-effect H 2 O/LiBr absorption chiller is developed. ► The chiller is driven by two heat sources and exclusively cooled by the ambient air. ► Heat and mass transfer in the absorber and the desorber are described according to a detailed physical model. ► Analyse of the dynamic behaviour of the chiller after sudden changes in operation. - Abstract: A dynamic model for the simulation of a new single-effect water/lithium bromide absorption chiller is developed. The chiller is driven by two distinct heat sources, includes a custom integrated falling film evaporator–absorber, uses mixed recirculation and is exclusively cooled by the ambient air. Heat and mass transfer in the evaporator–absorber and in the desorber are described according to a physical model for vapour absorption based on Nusselt’s film theory. The other heat exchangers are handled using a simplified approach based on the NTU-effectiveness method. The model is then used to analyze the chiller response to a step drop of the heat recovery circuit flow rate, and to a sudden reduction of the cooling need in the conditioned space. In the latter case, a basic temperature regulation system is simulated. In both simulations, the performance of the chiller is well represented and consistent with expectations.

  13. Thermodynamic modelling and parametric study of a low temperature vapour compression-absorption system based on modified Gouy-Stodola equation

    International Nuclear Information System (INIS)

    Jain, Vaibhav; Sachdeva, Gulshan; Kachhwaha, S.S.

    2015-01-01

    Present paper thermodynamically analyses a VCAS (vapour compression-absorption system) with carbon dioxide (compression section) and ammonia-water (absorption section) as refrigerants and determines the optimal condensing temperature of cascade condenser using modified Gouy-Stodola equation. The optimum cascade condenser temperature is found to be −13 °C for 175 kW refrigeration capacity at an evaporator temperature of −45 °C and condenser temperature of 35 °C. The optimum cascade condenser temperature maximises the overall COP, rational efficiency and minimises the total irreversibility rate of the VCAS system. The value of optimum condensing temperature and its corresponding maximum COP, and minimum irreversibility rate are discussed for a wide range of operating conditions. Further, a comparative study of TSVCS (two stage vapour compression system) used for low temperature refrigeration applications with VCAS shows that at design point, primary energy consumption is reduced by 60.6% and electrical COP is improved by 153.6% in VCAS as compared to conventional TSVCS. But the total irreversibility rate of VCAS is 38.4% higher than the TSVCS due to the use of low grade energy in vapour absorption system and hence the rational efficiency of VCAS is 14% low. - Highlights: • Optimum cascade condenser temperature with modified Gouy-Stodola law is analysed. • It maximises COP, rational efficiency and minimises total irreversibility. • 60.6% of primary energy is saved by cascaded absorption system. • Electrical COP is improved by 153.6% with cascaded absorption system

  14. Development and experimental testing of a hybrid Stirling engine-adsorption chiller auxiliary power unit for heavy trucks

    International Nuclear Information System (INIS)

    Flannery, Barry; Lattin, Robert; Finckh, Oliver; Berresheim, Harald; Monaghan, Rory F.D.

    2017-01-01

    Highlights: • Free-piston Stirling engine for truck APU. • Waste heat driven adsorption chiller for cab air conditioning. • Reduced-order model comparing proposed system to existing technology. • Experimental test data from prototype test rig. - Abstract: This paper identifies the key technical requirements for a heavy truck auxiliary power unit (APU) and explores a potential alternative technology for use in a next-generation APU which could eliminate key problems related to emissions, noise and maintenance experienced today by conventional diesel engine-vapour compression APUs. The potential performance of a novel hybrid Stirling engine-adsorption chiller concept is investigated and benchmarked against the incumbent technology using a reduced-order model based on experimental data. Experimental results from a Stirling-adsorption system (SAS) prototype test rig are also presented which highlight system integration dynamics and overall performance. The adsorption chiller achieved an average COP of 0.42 ± 0.06 and 2.3 ± 0.1 kW_t of cooling capacity at the baseline test condition. The prototype SAS test rig demonstrates that there appear to be no major technology barriers remaining that would prevent adoption of the SAS concept in a next-generation APU. Such a system could offer a reduction of exhaust emissions, greenhouse gases (GHG), ozone-depleting substances, noise, low maintenance and the potential for fuel flexibility and higher reliability. Preliminary modelling results indicate that the proposed system could offer superior overall electrical and cooling efficiencies compared to incumbent APUs and demonstrate a payback period of 4.6 years.

  15. Analytical computation of thermodynamic performance parameters of actual vapour compression refrigeration system with R22, R32, R134a, R152a, R290 and R1270

    Directory of Open Access Journals (Sweden)

    Vali Shaik Sharmas

    2018-01-01

    Full Text Available The present work focuses on analytical computation of thermodynamic performance of actual vapour compression refrigeration system by using six pure refrigerants. The refrigerants are namely R22, R32, R134a, R152a, R290 and R1270 respectively. A MATLAB code is developed to compute the thermodynamic performance parameters of actual vapour compression system such as refrigeration effect, compressor work, COP, power per ton of refrigeration, compressor discharge temperature and volumetric refrigeration capacity at condensing and evaporating temperatures of 54.4oC and 7.2oC respectively. Analytical results exhibited that COP of both R32 and R134a are 15.95% and 11.71% higher among the six investigated refrigerants. However R32 and R134a cannot be replaced directly into R22 system. This is due to their higher compressor discharge temperature and poor volumetric capacity respectively. The discharge temperature of both R1270 and R290 are lower than R22 by 20-26oC. Volumetric refrigeration capacity of R1270 (3197 kJ/m3 is very close to that of volumetric capacity of R22 (3251 kJ/m3. Both R1270 and R290 shows good miscibility with R22 mineral oil. Overall R1270 would be a suitable ecofriendly refrigerant to replace R22 from the stand point of ODP, GWP, volumetric capacity, discharge temperature and miscibility with mineral oil although its COP is lower.

  16. Thermodynamics of the ternary systems: (water + glycine, L-alanine and L-serine + di-ammonium hydrogen citrate) from volumetric, compressibility, and (vapour + liquid) equilibria measurements

    International Nuclear Information System (INIS)

    Sadeghi, Rahmat; Gholamireza, Afsaneh

    2011-01-01

    The apparent molar volumes and isentropic compressibility of glycine, L-alanine and L-serine in water and in aqueous solutions of (0.500 and 1.00) mol . kg -1 di-ammonium hydrogen citrate {(NH 4 ) 2 HCit} and those of (NH 4 ) 2 HCit in water have been obtained over the (288.15 to 313.15) K temperature range at 5 K intervals at atmospheric pressure from measurements of density and ultrasonic velocity. The apparent molar volume and isentropic compressibility values at infinite dilution of the investigated amino acids have been obtained and their variations with temperature and their transfer properties from water to aqueous solutions of (NH 4 ) 2 HCit have also been obtained. The results have been interpreted in terms of the hydration of the amino acids. In the second part of this work, water activity measurements by the isopiestic method have been carried out on the aqueous solutions of {glycine + (NH 4 ) 2 HCit}, {alanine + (NH 4 ) 2 HCit}, and {serine + (NH 4 ) 2 HCit} at T = 298.15 K at atmospheric pressure. From these measurements, values of vapour pressure, osmotic coefficient, activity coefficient and Gibbs free energy were obtained. The effect of the type of amino acids on the (vapour + liquid) equilibrium of the systems investigated has been studied. The experimental water activities have been correlated successfully with the segment-based local composition Wilson model. Furthermore, the thermodynamic behaviour of the ternary solutions investigated has been studied by using the semi-ideal hydration model and the linear concentration relations have been tested by comparing with the isopiestic measurements for the studied systems at T = 298.15 K.

  17. Thermodynamics of the ternary systems: (water + glycine, L-alanine and L-serine + di-ammonium hydrogen citrate) from volumetric, compressibility, and (vapour + liquid) equilibria measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Rahmat, E-mail: rahsadeghi@yahoo.co [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Gholamireza, Afsaneh [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2011-02-15

    The apparent molar volumes and isentropic compressibility of glycine, L-alanine and L-serine in water and in aqueous solutions of (0.500 and 1.00) mol . kg{sup -1} di-ammonium hydrogen citrate {l_brace}(NH{sub 4}){sub 2}HCit{r_brace} and those of (NH{sub 4}){sub 2}HCit in water have been obtained over the (288.15 to 313.15) K temperature range at 5 K intervals at atmospheric pressure from measurements of density and ultrasonic velocity. The apparent molar volume and isentropic compressibility values at infinite dilution of the investigated amino acids have been obtained and their variations with temperature and their transfer properties from water to aqueous solutions of (NH{sub 4}){sub 2}HCit have also been obtained. The results have been interpreted in terms of the hydration of the amino acids. In the second part of this work, water activity measurements by the isopiestic method have been carried out on the aqueous solutions of {l_brace}glycine + (NH{sub 4}){sub 2}HCit{r_brace}, {l_brace}alanine + (NH{sub 4}){sub 2}HCit{r_brace}, and {l_brace}serine + (NH{sub 4}){sub 2}HCit{r_brace} at T = 298.15 K at atmospheric pressure. From these measurements, values of vapour pressure, osmotic coefficient, activity coefficient and Gibbs free energy were obtained. The effect of the type of amino acids on the (vapour + liquid) equilibrium of the systems investigated has been studied. The experimental water activities have been correlated successfully with the segment-based local composition Wilson model. Furthermore, the thermodynamic behaviour of the ternary solutions investigated has been studied by using the semi-ideal hydration model and the linear concentration relations have been tested by comparing with the isopiestic measurements for the studied systems at T = 298.15 K.

  18. (Vapour + liquid) equilibria, volumetric and compressibility behaviour of binary and ternary aqueous solutions of 1-hexyl-3-methylimidazolium chloride, methyl potassium malonate, and ethyl potassium malonate

    International Nuclear Information System (INIS)

    Sadeghi, Rahmat; Mahdavi, Adibeh

    2012-01-01

    Highlights: ► VLE and volumetry of binary and ternary [C 6 mim][Cl], MPM and EPM aqueous solutions. ► Constant a w lines show small negative deviation from the linear isopiestic relation. ► Solute–water interactions follow the order: EPM > MPM > [C 6 mim][Cl]. ► MPM and EPM have a very weak salting-out effect on [C 6 mim][Cl] aqueous solutions. - Abstract: (Vapour + liquid) equilibrium data (water activity, vapour pressure, osmotic coefficient, and activity coefficient) of binary aqueous solutions of 1-hexyl-3-methylimidazolium chloride ([C 6 mim][Cl]), methyl potassium malonate, and ethyl potassium malonate and ternary {[C 6 mim][Cl] + methyl potassium malonate} and {[C 6 mim][Cl] + ethyl potassium malonate} aqueous solutions were obtained through the isopiestic method at T = 298.15 K. These results reveal that the ionic liquid behaves as surfactant-like and aggregates in aqueous solutions at molality about 0.4 mol · kg −1 . The constant water activity lines of all the ternary systems investigated show small negative deviations from the linear isopiestic relation (Zdanovskii–Stokes–Robinson rule) derived using the semi-ideal hydration model. The density and speed of sound measurements were carried out on solutions of methyl potassium malonate and ethyl potassium malonate in water and of [C 6 mim][Cl] in aqueous solutions of 0.25 mol · kg −1 methyl potassium malonate and ethyl potassium malonate at T = (288.15 to 308.15) K at atmospheric pressure. From the experimental density and speed of sound data, the values of the apparent molar volume, apparent molar isentropic compressibility and excess molar volume were evaluated and from which the infinite dilution apparent molar volume and infinite dilution apparent molar isentropic compressibility were calculated at each temperature. Although, there are no clear differences between the values of the apparent molar volume of [C 6 mim][Cl] in pure water and in methyl potassium malonate or ethyl

  19. Robustness analysis of chiller sequencing control

    International Nuclear Information System (INIS)

    Liao, Yundan; Sun, Yongjun; Huang, Gongsheng

    2015-01-01

    Highlights: • Uncertainties with chiller sequencing control were systematically quantified. • Robustness of chiller sequencing control was systematically analyzed. • Different sequencing control strategies were sensitive to different uncertainties. • A numerical method was developed for easy selection of chiller sequencing control. - Abstract: Multiple-chiller plant is commonly employed in the heating, ventilating and air-conditioning system to increase operational feasibility and energy-efficiency under part load condition. In a multiple-chiller plant, chiller sequencing control plays a key role in achieving overall energy efficiency while not sacrifices the cooling sufficiency for indoor thermal comfort. Various sequencing control strategies have been developed and implemented in practice. Based on the observation that (i) uncertainty, which cannot be avoided in chiller sequencing control, has a significant impact on the control performance and may cause the control fail to achieve the expected control and/or energy performance; and (ii) in current literature few studies have systematically addressed this issue, this paper therefore presents a study on robustness analysis of chiller sequencing control in order to understand the robustness of various chiller sequencing control strategies under different types of uncertainty. Based on the robustness analysis, a simple and applicable method is developed to select the most robust control strategy for a given chiller plant in the presence of uncertainties, which will be verified using case studies

  20. Truck Thermoacoustic Generator and Chiller

    Energy Technology Data Exchange (ETDEWEB)

    Keolian, Robert

    2011-03-31

    This Final Report describes the accomplishments of the US Department of Energy (DOE) cooperative agreement project DE-FC26-04NT42113 - Truck Thermoacoustic Generator and Chiller - whose goal is to design, fabricate and test a thermoacoustic piezoelectric generator and chiller system for use on over-the-road heavy-duty-diesel trucks, driven alternatively by the waste heat of the main diesel engine exhaust or by a burner integrated into the thermoacoustic system. The thermoacoustic system would utilize engine exhaust waste heat to generate electricity and cab air conditioning, and would also function as an auxiliary power unit (APU) for idle reduction. The unit was to be tested in Volvo engine performance and endurance test cells and then integrated onto a Class 8 over-the-road heavy-duty-diesel truck for further testing on the road. The project has been a collaboration of The Pennsylvania State University Applied Research Laboratory, Los Alamos National Laboratory, Clean Power Resources Inc., and Volvo Powertrain (Mack Trucks Inc.). Cost share funding was provided by Applied Research Laboratory, and by Clean Power Resources Inc via its grant from Innovation Works - funding that was derived from the Commonwealth of Pennsylvania. Los Alamos received its funding separately through DOE Field Work Proposal 04EE09.

  1. Absorption chillers: Part of the solution

    International Nuclear Information System (INIS)

    Occhionero, A.J.; Hughes, P.J.; Reid, E.A.

    1991-01-01

    Acid rain, ozone depletion, global warming, and implementation economics are considered as they relate to the advisability of expanding the application of absorption chillers. Introductory and background information are provided to put the discussion in the proper context. Then all four issues are discussed separately as they relate to absorption chillers. Acid rain and ozone depletion concerns, and implementation economics, are found to support the expanded use of absorption chillers. The global warming concern is found to be more of a gray area, but the areas of benefit correspond well with the conditions of greatest economic advantage. All things considered, absorption chillers are believed to be part of the environmental and economic solution. It is further believed that integrated resource planning (IRP) processes that consider electric and gas technologies on an equal footing would come to the same conclusion for many regions of the United States. 9 refs., 3 tabs

  2. Performance evaluation of a solar adsorption chiller under different climatic conditions

    International Nuclear Information System (INIS)

    Alahmer, Ali; Wang, Xiaolin; Al-Rbaihat, Raed; Amanul Alam, K.C.; Saha, B.B.

    2016-01-01

    Highlights: • A solar adsorption cooling system was studied at different climatic conditions. • Effect of hot water temperature and flow rate on system performance was evaluated. • Solar collector area and tilting angle largely affected the system performance. • Economics of the solar adsorption cooling was analysed at real weather conditions. • Adsorption cooling could be potentially applied in cities with good solar radiation. - Abstract: Performance of an adsorption cooling system driven by solar thermal energy was studied under different climatic conditions. The effects of solar collector area, collector slope, hot water temperature and flow rate on the system performance were investigated using the real-time weather data of two cities: Perth, Australia (a representative city in the southern hemisphere) and Amman, Jordan (a representative city in the northern hemisphere). The simulation results showed that the two cities had similar solar radiation during the summer period and that the solar adsorption chiller could reliably provide cooling at a reasonably high system COP. For residential cooling with a total CPC (Compound Parabolic Collector) solar collector area of 36.22 m"2, the average system COP was 0.491 for Perth weather conditions and 0.467 for Amman weather conditions, respectively while the cooling capacity was 10.3 kW for Perth and 8.46 kW for Amman, respectively at peak times. Optimum performance occurred when the system run with the CPC collector slope of around 30°, the solar water storage tank volume of 1.4 m"3, inlet hot water temperature of 80 °C, and a hot water flow rate of 0.33 kg/s. An economic analysis was further investigated and the results showed that the solar driven adsorption cooling system could reduce the electricity consumption for Perth and Amman cities by 34% and 28%, respectively in comparison to a conventional vapour compression cooling system.

  3. T Plant removal of PWR Chiller Subsystem

    International Nuclear Information System (INIS)

    Dana, C.M.

    1994-01-01

    The PWR Pool Chiller System is not longer required for support of the Shippingport Blanket Fuel Assemblies Storage. The Engineering Work Plan will provide the overall coordination of the documentation and physical changes to deactivate the unneeded subsystem. The physical removal of all energy sources for the Chiller equipment will be covered under a one time work plan. The documentation changes will be covered using approved Engineering Change Notices and Procedure Change Authorizations as needed

  4. Performance Analysis of Waste Heat Driven Pressurized Adsorption Chiller

    KAUST Repository

    LOH, Wai Soong; SAHA, Bidyut Baran; CHAKRABORTY, Anutosh; NG, Kim Choon; CHUN, Won Gee

    2010-01-01

    This article presents the transient modeling and performance of waste heat driven pressurized adsorption chillers for refrigeration at subzero applications. This innovative adsorption chiller employs pitch-based activated carbon of type Maxsorb III

  5. SAPO-34 coated adsorbent heat exchanger for adsorption chillers

    International Nuclear Information System (INIS)

    Freni, Angelo; Bonaccorsi, Lucio; Calabrese, Luigi; Caprì, Angela; Frazzica, Andrea; Sapienza, Alessio

    2015-01-01

    In this work, adsorbent coatings on aluminum surfaces were prepared by dip-coating method starting from a water suspension of SAPO-34 zeolite and a silane-based binder. Silane-zeolite coatings morphology and surface coverage grade were evaluated by scanning electron microscopy. Adhesive and mechanical properties were evaluated by peel, pull-off, impact and micro-hardness tests, confirming the good interaction between metal substrate, binder and zeolite. Adsorption equilibrium and kinetics of water vapour adsorption on the adsorbent coating were studied in the range T = 30–150 °C and pH 2 O = 11 mbar using a CAHN 2000 thermo-balance. It was found that, in the investigated conditions, the organic binder doesn't affect the water adsorption capacity and adsorption kinetics of the original SAPO-34 zeolite. Subsequently, the zeolite coating was applied on a finned flat-tubes aluminum heat exchanger realizing a full-scale AdHEx with an uniform adsorbent coating 0.1 mm thick and a metal/adsorbent mass ratio = 6. The cooling capacity of the realized coated AdHEx was measured by a lab-scale adsorption chiller under realistic operating conditions for air conditioning applications. The coated AdHEx produced up to 675 W/kg ads specific cooling power with a cycle time of 5 min. Adsorption stability of the coated adsorber subjected to 600 sorption cycles was successfully verified. - Highlights: • Adsorbent coatings on aluminum surfaces were prepared by dip-coating method. • Silane-zeolite coatings morphology, and mechanical properties were studied. • The zeolite coating was applied on a finned flat-tubes aluminum heat exchanger. • The coated AdHEx was tested in a lab scale adsorption chiller

  6. Cost justification of chiller replacement

    International Nuclear Information System (INIS)

    Baker, T.J.; Baumer, R.A.

    1993-01-01

    We often hear of products with paybacks that are too good to be true. Just a few weeks ago,a client received a recommendation from a national service company's local office. In the letter the company recommended that open-quotes due to the age and condition of the boiler ... that the school consider replacing the boiler... The cost for the new boiler can usually be recovered by lower fuel bills in 2 to 3 yearsclose quotes. This was for an installation in Southeast Texas where the boiler is only used 4 to 5 months per year. Analysis show the above claims to be nonsense. A new boiler would cost about $47,000 installed. Current total gas bills for the facility are $15,630 per year. They would have to shutoff the gas to the facility to have a three year payback. In fact, only two-thirds of the gas is used to heat the facility so we have only $10, 000 to write off against the new boiler. How much will the greater efficiency save? A 30% savings due to greater efficiency produces $3,000 per year in gas savings to offset the $47,000 cost, a 16 year payback. And much of the efficiency savings can be realized by adjusting the existing boiler. In another care a client wanted to investigate replacement of a twenty year old chiller plant with more efficient equipment. We investigated the project and determined that the payback would be greater than ten years. They did not operate the equipment during the summer and at less than 50% of capacity the balance of the year

  7. INNOVATIVE HYBRID GAS/ELECTRIC CHILLER COGENERATION

    Energy Technology Data Exchange (ETDEWEB)

    Todd Kollross; Mike Connolly

    2004-06-30

    Engine-driven chillers are quickly gaining popularity in the market place (increased from 7,000 tons in 1994 to greater than 50,000 tons in 1998) due to their high efficiency, electric peak shaving capability, and overall low operating cost. The product offers attractive economics (5 year pay back or less) in many applications, based on areas cooling requirements and electric pricing structure. When heat is recovered and utilized from the engine, the energy resource efficiency of a natural gas engine-driven chiller is higher than all competing products. As deregulation proceeds, real time pricing rate structures promise high peak demand electric rates, but low off-peak electric rates. An emerging trend with commercial building owners and managers who require air conditioning today is to reduce their operating costs by installing hybrid chiller systems that combine gas and electric units. Hybrid systems not only reduce peak electric demand charges, but also allow customers to level their energy load profiles and select the most economical energy source, gas or electricity, from hour to hour. Until recently, however, all hybrid systems incorporated one or more gas-powered chillers (engine driven and/or absorption) and one or more conventional electric units. Typically, the cooling capacity of hybrid chiller plants ranges from the hundreds to thousands of refrigeration tons, with multiple chillers affording the user a choice of cooling systems. But this flexibility is less of an option for building operators who have limited room for equipment. To address this technology gap, a hybrid chiller was developed by Alturdyne that combines a gas engine, an electric motor and a refrigeration compressor within a single package. However, this product had not been designed to realize the full features and benefits possible by combining an engine, motor/generator and compressor. The purpose of this project is to develop a new hybrid chiller that can (1) reduce end-user energy

  8. Cooling performance and energy saving of a compression-absorption refrigeration system driven by a gas engine

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Z.G.; Guo, K.H. [Sun Yat-Sen University, Guangzhou (China). Engineering School

    2006-07-01

    The prototype of combined vapour compression-absorption refrigeration system was set up, where a gas engine drove directly an open screw compressor in a vapour compression refrigeration chiller and waste heat from the gas engine was used to operate absorption refrigeration cycle. The experimental procedure and results showed that the combined refrigeration system was feasible. The cooling capacity of the prototype reached about 589 kW at the Chinese rated conditions of air conditioning (the inlet and outlet temperatures of chilled water are 12 and 7{sup o}C, the inlet and outlet temperatures of cooling water are 30 and 35{sup o}C, respectively). Primary energy rate (PER) and comparative primary energy saving were used to evaluate energy utilization efficiency of the combined refrigeration system. The calculated results showed that the PER of the prototype was about 1.81 and the prototype saved more than 25% of primary energy compared to a conventional electrically driven vapour compression refrigeration unit. Error analysis showed that the total error of the combined cooling system measurement was about 4.2% in this work. (author)

  9. Solution quality improvement in chiller loading optimization

    International Nuclear Information System (INIS)

    Geem, Zong Woo

    2011-01-01

    In order to reduce greenhouse gas emission, we can energy-efficiently operate a multiple chiller system using optimization techniques. So far, various optimization techniques have been proposed to the optimal chiller loading problem. Most of those techniques are meta-heuristic algorithms such as genetic algorithm, simulated annealing, and particle swarm optimization. However, this study applied a gradient-based method, named generalized reduced gradient, and then obtains better results when compared with other approaches. When two additional approaches (hybridization between meta-heuristic algorithm and gradient-based algorithm; and reformulation of optimization structure by adding a binary variable which denotes chiller's operating status) were introduced, generalized reduced gradient found even better solutions. - Highlights: → Chiller loading problem is optimized by generalized reduced gradient (GRG) method. → Results are compared with meta-heuristic algorithms such as genetic algorithm. → Results are even enhanced by hybridizing meta-heuristic and gradient techniques. → Results are even enhanced by modifying the optimization formulation.

  10. Analysis of chiller units capacity for different heat loads considering variation of ambient air and cooling water temperature

    International Nuclear Information System (INIS)

    Coman, Aurelia Camelia; Tenescu, Mircea

    2010-01-01

    The paper purpose is to analyze the chiller units capacity to determine whether they can cope with high air and cooling water temperatures during summer time to remove heat loads imposed from Heating, Ventilation and Air Conditioning (HVAC) units in a CANDU 6 Nuclear Power Plant. The starting point is calculation of the overall heat transfer coefficient at the evaporator and condenser. They are used in heat balance equations of heat exchangers. A mathematical model was developed that simulates the refrigeration cycle to assess the response of chilled water system and its performance at different heat loads. In this analysis there were calculated values for inlet/outlet chilled water temperature and the refrigerant cycle thermodynamic parameters (condenser and evaporator pressure/temperature, refrigerant mass flowrate, refrigerant quality at the evaporator, refrigerant vapour superheated temperature at the compressor outlet, refrigerant subcooled temperature at the condenser outlet). To find the adequate functioning parameters of the installation, the MathCAD 13 software was used in all cases analyzed. The behaviour of the chiller units was investigated by examining the variation of three basic parameters, namely: - cooling water (river water) temperature; - air temperature; - heat load. The simultaneous variation of these three independent parameters allows to identify the actual chillers unit operating point (including chiller trip). (authors)

  11. Experimental and numerical study of two-phase flows at the inlet of evaporators in vapour compression cycles; Etude experimentale et numerique d'ecoulements diphasiques a l'entree des evaporateurs de cycles thermodynamiques

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, M

    2007-09-15

    Maldistribution of liquid-vapour two phase flows causes a significant decrease of the thermal and hydraulic performance of evaporators in thermodynamic vapour compression cycles. A first experimental installation was used to visualize the two phase flow evolution between the expansion valve and the evaporator inlet. A second experimental set-up simulating a compact heat exchanger has been designed to identify the functional and geometrical parameters creating the best distribution of the two phases in the different channels. An analysis and a comprehension of the relation between the geometrical and functional parameters with the flow pattern inside the header and the two phase distribution, has been established. A numerical simulations of a stratified flow and a stratified jet flow have been carried out using two CFD codes: FLUENT and NEPTUNE. In the case of a fragmented jet configuration, a global definition of the interfacial area concentration for a separated phases and dispersed phases flow has been established and a model calculating the fragmented mass fraction has been developed. (author)

  12. Performance characteristics of single effect lithium bromide/ water absorption chiller for small data centers

    Science.gov (United States)

    Mysore, Abhishek Arun Babu

    A medium data center consists of servers performing operations such as file sharing, collaboration and email. There are a large number of small and medium data centers across the world which consume more energy and are less efficient when compared to large data center facilities of companies such as GOOGLE, APPLE and FACEBOOK. Such companies are making their data center facilities more environmental friendly by employing renewable energy solutions such as wind and solar to power the data center or in data center cooling. This not only reduces the carbon footprint significantly but also decreases the costs incurred over a period of time. Cooling of data center play a vital role in proper functioning of the servers. It is found that cooling consumes about 50% of the total power consumed by the data center. Traditional method of cooling includes the use of mechanical compression chillers which consume lot of power and is not desirable. In order to eliminate the use of mechanical compressor chillers renewable energy resources such as solar and wind should be employed. One such technology is solar thermal cooling by means of absorption chiller which is powered by solar energy. The absorption chiller unit can be coupled with either flat plate or evacuated tube collectors in order to achieve the required inlet temperature for the generator of the absorption chiller unit. In this study a modular data center is considered having a cooling load requirement of 23kw. The performance characteristics of a single stage Lithium Bromide/ water refrigeration is presented in this study considering the cooling load of 23kw. Performance characteristics of each of the 4 heat exchangers within the unit is discussed which helps in customizing the unit according to the users' specific needs. This analysis helps in studying the importance of different properties such as the effect of inlet temperatures of hot water for generator, inlet temperatures of cooling water for absorber and

  13. Development of an Innovative 2.5 kW Water-Silica Gel Adsorption Chiller

    Energy Technology Data Exchange (ETDEWEB)

    Bakker, E.J.; De Boer, R.; Smeding, S.F.; Sijpheer, N.C.; Van der Pal, M.

    2013-10-15

    Besides (better) utilization of available solar heat or waste heat, and thereby reduction of fossil fuel consumption, sorption cooling offers several other advantages compared to conventional compression cooling. Such as reduction of summer peaks in the electricity grid, use of natural refrigerants, and low noise and maintenance. Sorption cooling in itself is not a new development. However, the development of small scale sorption chillers (2-20 kW) is new. This development allows sorption cooling to enter the markets for individual homes, small collective systems and small commercial applications. A second trend is gradual reduction of the driving temperatures of the sorption cycles allowing more solar and waste heat to be used. This article describes the design and performance of a new, innovative 2.5 kW adsorption chiller, developed by ECN. This system was built and tests have been performed in a laboratory and in one of ECN's full-scale research houses.

  14. Controladores fuzzy adaptativos para la optimización de un sistema chiller

    Directory of Open Access Journals (Sweden)

    Moreno G. Francisco. E.

    2011-01-01

    Full Text Available The chiller systems are vapor compression cycles used in industrial and residential applications, operated a classical control and inadequate under energy consumption point of view. The experimental work, development in the Energy and Thermal System Laboratory of Federal University of Uberlandia (UFU, investigates some advantages of the use of variable speed compressor and electronic expansion valves focusing on energy consumption reduction and increase of the coefficient of performance, (COP of these chillers systems. In these conditions, a proposed model experimentally based on experimental planning techniques, applying tools of answer surfaces. This model allows the estimative of the dynamic behavior of the compressor frequency to contribute in the control mesh applying adaptative fuzzy strategies, showing a good performance on the system, searching a minimum degree of superheating in the order of the 7°C and reaching on the bests COP zones.

  15. Amelioration of the cooling load based chiller sequencing control

    International Nuclear Information System (INIS)

    Huang, Sen; Zuo, Wangda; Sohn, Michael D.

    2016-01-01

    Highlights: • We developed a new approach for the optimal load distribution for chillers. • We proposed a new approach to optimize the number of operating chillers. • We provided a holistic solution to address chiller sequencing control problems. - Abstract: Cooling Load based Control (CLC) for the chiller sequencing is a commonly used control strategy for multiple-chiller plants. To improve the energy efficiency of these chiller plants, researchers proposed various CLC optimization approaches, which can be divided into two groups: studies to optimize the load distribution and studies to identify the optimal number of operating chillers. However, both groups have their own deficiencies and do not consider the impact of each other. This paper aims to improve the CLC by proposing three new approaches. The first optimizes the load distribution by adjusting the critical points for the chiller staging, which is easier to be implemented than existing approaches. In addition, by considering the impact of the load distribution on the cooling tower energy consumption and the pump energy consumption, this approach can achieve a better energy saving. The second optimizes the number of operating chillers by modulating the critical points and the condenser water set point in order to achieve the minimal energy consumption of the entire chiller plant that may not be guaranteed by existing approaches. The third combines the first two approaches to provide a holistic solution. The proposed three approaches were evaluated via a case study. The results show that the total energy consumption saving for the studied chiller plant is 0.5%, 5.3% and 5.6% by the three approaches, respectively. An energy saving of 4.9–11.8% can be achieved for the chillers at the cost of more energy consumption by the cooling towers (increases of 5.8–43.8%). The pumps’ energy saving varies from −8.6% to 2.0%, depending on the approach.

  16. Global climate change: Mitigation opportunities high efficiency large chiller technology

    Energy Technology Data Exchange (ETDEWEB)

    Stanga, M.V.

    1997-12-31

    This paper, comprised of presentation viewgraphs, examines the impact of high efficiency large chiller technology on world electricity consumption and carbon dioxide emissions. Background data are summarized, and sample calculations are presented. Calculations show that presently available high energy efficiency chiller technology has the ability to substantially reduce energy consumption from large chillers. If this technology is widely implemented on a global basis, it could reduce carbon dioxide emissions by 65 million tons by 2010.

  17. Chillers and cold water units. Special issue; Chillers en koudwateraggregaten. Thema

    Energy Technology Data Exchange (ETDEWEB)

    Van Zwam, P. [GEA Refrigeration Components Benelux, Den Bosch (Netherlands); Meijer, W. [Daikin Airconditioning Netherlands, Rotterdam (Netherlands); Torsy, E. [Trane Airconditioning, Soest (Netherlands); Berends, E. [GEA Grenco Refrigeration, Den Bosch (Netherlands); Havenaar, D. (ed.)

    2010-05-15

    In five articles attention is paid to several aspects of chillers and cold water units: (1) reduction of refrigerants and increase of the COP; (2) realization of high partial load efficiency in mono-screw compressors; (3) energy efficient innovation for cooling and heat pump systems; (4) application of modern chiller technology for a skating rink of Sportboulevard, Dordrecht, Netherlands; and (5) the use of propane as a refrigerant in air-cooled cold water units. [Dutch] In vijf artikelen wordt aandacht besteed aan verschillende aspecten van chillers en koudwateraggregaten: (1) minimaliseren van koudemiddeleninhoud en verhogen van de COP; (2) realisatie van hoge deellastrendementen met mono-schroefcompressoren; (3) energie efficiente innovaties voor koelmachine- en warmtepompsystemen; (4) toepassing van moderne chillertechnologie in de ijshal van Sportboulevard Dordrecht; en (5) het gebruik van propaan als koudemiddel in luchtgekoelde koudwateraggregaten.

  18. Chapter 14: Chiller Evaluation Protocol. The Uniform Methods Project: Methods for Determining Energy Efficiency Savings for Specific Measures

    Energy Technology Data Exchange (ETDEWEB)

    Kurnik, Charles W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tiessen, Alex [Posterity Group, Ottawa, ON (Canada)

    2017-10-06

    This protocol defines a chiller measure as a project that directly impacts equipment within the boundary of a chiller plant. A chiller plant encompasses a chiller - or multiple chillers - and associated auxiliary equipment. This protocol primarily covers electric-driven chillers and chiller plants. It does not include thermal energy storage and absorption chillers fired by natural gas or steam, although a similar methodology may be applicable to these chilled water system components.

  19. Theoretical and testing performance of an innovative indirect evaporative chiller

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yi; Xie, Xiaoyun [Department of Building Science and Technology, Tsinghua University, Beijing (China)

    2010-12-15

    An indirect evaporative chiller is a device used to produce chilled water at a temperature between the wet bulb temperature and dew point of the outdoor air, which can be used in building HVAC systems. This article presents a theoretical analysis and practical performance of an innovative indirect evaporative chiller. First, the process of the indirect evaporative chiller is introduced; then, the matching characteristics of the process are presented and analyzed. It can be shown that the process that produces cold water by using dry air is a nearly-reversible process, so the ideal produced chilled water temperature of the indirect evaporative chiller can be set close to the dew point temperature of the chiller's inlet air. After the indirect evaporative chiller was designed, simulations were done to analyze the output water temperature, the cooling efficiency relative to the inlet dew point temperature, and the COP that the chiller can performance. The first installation of the indirect evaporative chiller of this kind has been run for 5 years in a building in the city of Shihezi. The tested output water temperature of the chiller is around 14-20 C, which is just in between of the outdoor wet bulb temperature and dew point. The tested COP{sub r,s} of the developed indirect evaporative chiller reaches 9.1. Compared with ordinary air conditioning systems, the indirect evaporative chiller can save more than 40% in energy consumption due to the fact that the only energy consumed is from pumps and fans. An added bonus is that the indirect evaporative chiller uses no CFCs that pollute to the aerosphere. The tested internal parameters, such as the water-air flow rate ratio and heat transfer area for each heat transfer process inside the chiller, were analyzed and compared with designed values. The tested indoor air conditions, with a room temperature of 23-27 C and relative humidity of 50-70%, proved that the developed practical indirect evaporative chiller

  20. Studies on Steam Absorption Chillers Performance at a Cogeneration Plant

    Directory of Open Access Journals (Sweden)

    Abd Majid Mohd Amin

    2014-07-01

    Full Text Available Absorption chillers at cogeneration plants generate chilled water using steam supplied by heat recovery steam generators. The chillers can be of either single-effect or double effect configuration and the coefficient of performance (COP depends on the selection made. The COP varies from 0.7 to 1.2 depending on the types of chillers. Single effect chillers normally have COP in the range of 0.68 to 0.79. Double effect chillers COP are higher and can reach 1.2. However due to factors such as inappropriate operations and maintenance practices, COP could drop over a period of time. In this work the performances of double effect steam absorption chillers at a cogeneration plant were studied. The study revealed that during the period of eleven years of operation the COP of the chillers deteriorated from 1.25 to 0.6. Regression models on the operation data indicated that the state of deterioration was projected to persist. Hence, it would be recommended that the chillers be considered for replacement since they had already undergone a series of costly repairs.

  1. Using the adsorption chillers for waste heat utilisation from the CCS installation

    Science.gov (United States)

    Sztekler, Karol; Kalawa, Wojciech; Nowak, Wojciech; Stefański, Sebastian; Krzywański, Jarosław; Grabowska, Karolina

    2018-06-01

    Worldwide tendencies in the scope of environmental protection demonstrate the requirement for the limited carbon dioxide emission, that influences on the development of greenhouse effect. As a result of coal as a basic fuel used in the professional power industry, this industry sector is the greatest CO2 polluter and it means that works on the reduction of carbon dioxide in such industry are completely justified. In the IPSEpro programming environment, a reference block model for a conventional coal power station was elaborated, including the CO2 separation unit basing on the adsorption methods with the CO2 preparation installation to liquid state. Simulation researches were conducted with means of numeric techniques, that enabled the system analysis for the CO2 separation unit with the CO2 preparation system to the liquid state, as well as analysis was made for the use of chiller systems, basing on the adsorption technology for waste heat use originating from the compression of CO2 in a cascade system, as well as for potential opportunities for further exploitation of the produced chilled water in the CCS cycle. We analysed in these papers the opportunities for chiller systems application, based on the adsorption chillers in the CCS installation used for the reduction of CO2 emission in the coal power station and its influence on the operation of a power station cycle.

  2. Experimental study of adsorption chiller driven by variable heat source

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.C.; Wang, Y.J.; Zhang, J.P.; Tian, X.L. [College of Electromechanical Engineering, Qingdao University, Qingdao 266071 (China); Wu, J.Y. [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2008-05-15

    A silica gel-water adsorption chiller has been developed in recent years and has been applied in an air conditioning system driven by solar energy. The heat source used to drive the adsorption chiller is variable at any moment because the solar radiation intensity or the waste heat from engines varies frequently. An adsorption cooling system may be badly impacted by a variable heat source with temperature variations in a large range. In this work, a silica gel-water adsorption chiller driven by a variable heat source is experimentally studied. The influences of the variable heat source on the performance of the chiller are analyzed, especially for a continuous temperature increase process and a continuous temperature decrease process of the heat source. As an example, the dynamic characteristics of the heat source are also analyzed when solar energy is taken as the heat source of the adsorption chiller. According to the experimental results for the adsorption chiller and the characteristics of the heat source from solar energy, control strategies of the adsorption chiller driven by solar energy are proposed. (author)

  3. Seismic qualification for water chillers of nuclear power plant

    International Nuclear Information System (INIS)

    Wang Chunming

    2005-01-01

    Water chillers are important components of the electric building chilled water system of Nuclear Power Plant. In this article, we describe the seismic qualification methodology. A united method of seismic analysis and experiment testing were applied. Since the seismic classification of the evaporator, condenser and oil separator is 1F, the chillers must satisfy the function criteria. The functional and performance of the control panel were qualified by seismic test. In order to get the seismic time histories of the base of the motor, compressor and control panel, we did time histories analysis for the whole chillers using the seismic acceleration time history of the building floor on which the water chillers was located. Then, these curves were translated into required response spectrum (RRS), which were used by the seismic test of water chillers compressor sets. All passive components, such as evaporator, condenser, oil separator and support, were qualified by seismic stress analysis method. These components were verified to satisfy the standard when they were subjected to the seismic, gravitational, operational pressure and nozzle loads. The Chillers' components were qualified to the specification and the standard. The motor-compressor set and control panel were qualified to the functional and performance criteria. The applied of this methodology qualified the function of the water chillers compressor sets effectively, especially after the aging test. (author)

  4. Experimental study of adsorption chiller driven by variable heat source

    International Nuclear Information System (INIS)

    Wang, D.C.; Wang, Y.J.; Zhang, J.P.; Tian, X.L.; Wu, J.Y.

    2008-01-01

    A silica gel-water adsorption chiller has been developed in recent years and has been applied in an air conditioning system driven by solar energy. The heat source used to drive the adsorption chiller is variable at any moment because the solar radiation intensity or the waste heat from engines varies frequently. An adsorption cooling system may be badly impacted by a variable heat source with temperature variations in a large range. In this work, a silica gel-water adsorption chiller driven by a variable heat source is experimentally studied. The influences of the variable heat source on the performance of the chiller are analyzed, especially for a continuous temperature increase process and a continuous temperature decrease process of the heat source. As an example, the dynamic characteristics of the heat source are also analyzed when solar energy is taken as the heat source of the adsorption chiller. According to the experimental results for the adsorption chiller and the characteristics of the heat source from solar energy, control strategies of the adsorption chiller driven by solar energy are proposed

  5. The Liquid Vapour Interface

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1985-01-01

    In this short review we are concerned with the density variation across the liquid-vapour interface, i.e. from the bulk density of the liquid to the essentially zero density of the vapour phase. This density variation can in principle be determined from the deviation of the reflectivity from...

  6. Application of heat in postcook meat chillers reduces Listeria.

    Science.gov (United States)

    Eglezos, Sofroni; Dykes, Gary A

    2011-06-01

    Electrical air-blowing heaters were used to heat and dry out holding chillers used for postcook commercial processed meats in an attempt to control the presence of Listeria. A baseline study of the prevalence of Listeria in holding chillers in seven facilities was undertaken. Listeria was detected in four of the seven chillers, and swab samples showed Listeria prevalence ranging from 7 (7.8%) of 90 to 6 (20%) of 30, depending on the facility. Two of the facilities with established Listeria contamination (A and E) were chosen for further studies. The heating trials consisted of three individual heating interventions at each of the two facilities, with 2 weeks of postintervention sampling after each treatment. The initial Listeria prevalence in chiller A was 19 (10.6%) of 180, and treatment at 37°C for 36 h reduced prevalence to 3 (1.7%) of 180. The initial Listeria prevalence in chiller E was 7 (7.8%) of 90, and treatment at 50°C for 2 h reduced prevalence to 0 of 90. Both reductions were statistically significant at P prevalence of Listeria in chillers.

  7. Optimizing condenser fan control for air-cooled centrifugal chillers

    Energy Technology Data Exchange (ETDEWEB)

    Yu, F.W.; Chan, K.T. [Dept. of Building Services Engineering, The Hong Kong Polytechnic Univ., Hung Hom, Hong Kong (China)

    2008-07-15

    The current design and operation of air-cooled condensers can cause a significant decrease in chiller performance under part load conditions. This paper demonstrates optimal condenser fan control to improve the coefficient of performance (COP) of air-cooled chillers. This control involves identifying the optimum set point of condensing temperature with the optimized power relationships of the compressors and condenser fans and enhancing the airflow and heat transfer area of the condensers. An example application of this control for an air-cooled centrifugal chiller indicated that the COP could increase by 11.4-237.2%, depending on the operating conditions. Such the increase of the COP results in a reduction of up to 14.1 kWh/m{sup 2}, or 27.3% in the annual electricity consumption per unit A/C floor area of chillers, given that the chillers serve an office building requiring an annual cooling energy per unit A/C floor area of 173.3 kWh/m{sup 2}. The simulation results of this study will give HVAC engineers a better understanding of how to optimize the design and operation of air-cooled chillers. (author)

  8. Simulation Model for Dynamic Operation of Double-Effect Absorption Chillers

    Directory of Open Access Journals (Sweden)

    Ahmed Mojahid Sid Ahmed Mohammed Salih

    2014-07-01

    Full Text Available The development in the field of refrigeration and air conditioning systems driven by absorption cycles acquired a considerable importance recently. For commercial absorption chillers, an essential challenge for creating chiller model certainly is the shortage of components technical specifications. These kinds of specifications are usually proprietary for chillers producers. In this paper, a double-effect parallel-flow-type steam absorption chiller model based on thermodynamic and energy equations is presented. The chiller studied is Lithium bromide-water with capacity of 1250 RT (Refrigeration Tons. The governing equations of the dynamic operation of the chiller are developed. From available design information, the values of the overall heat transfer coefficients multiplied by the surface area are computed. The dynamic operation of the absorption chiller is simulated to study the performance of the system. The model is able to provide essential details of the temperature, concentration, and flow rate at each state point in the chiller.

  9. Performance Investigation of a Solar Heat Driven Adsorption Chiller under Two Different Climatic Conditions

    Science.gov (United States)

    Choudhury, Biplab; Chatterjee, Pradip Kumar; Habib, Khairul; Saha, Bidyut Baran

    2018-06-01

    The demand for cooling, especially in the developing economies, is rising at a fast rate. Fast-depleting sources of fossil fuel and environmental concerns necessitate looking for alternative cooling solutions. Solar heat driven adsorption based cooling cycles are environmentally friendly due to their use of natural refrigerants and the thermal compression process. In this paper, a performance simulation study of a basic two-bed solar adsorption chiller has been performed through a transient model for two different climatic locations in India. Effect of operating temperatures and cycle time on the chiller performance has been studied. It is observed that the solar hot water temperature obtained in the composite climate of Delhi (28.65°N, 77.25°E) can run the basic adsorption cooling cycle efficiently throughout the year. Whereas, the monsoon months of July and August in the warm and humid climate of Durgapur (23.48°N, 87.32°E) are unable to supply the required driving heat.

  10. Comparison and Analysis of Lithium Bromide-water Absorption Chillers Using Plastic Heat Transfer Tubes and Traditional Lithium Bromide-water Absorption Chillers

    OpenAIRE

    Xue-dong Zhang

    2010-01-01

    There are extensive applications of lithium bromide-water absorption chillers in industry, but the heat exchangers corrosion and refrigerating capacity loss are very difficult to be solved. In this paper, an experiment was conducted by using plastic heat transfer tubes instead of copper tubes. As an example, for a lithium bromide-water absorption chiller of refrigerating capacity of 35kW, the correlative performance of the lithium bromide-water absorption chiller using pl...

  11. Energy optimization methodology of multi-chiller plant in commercial buildings

    International Nuclear Information System (INIS)

    Thangavelu, Sundar Raj; Myat, Aung; Khambadkone, Ashwin

    2017-01-01

    This study investigates the potential energy savings in commercial buildings through optimized operation of a multi-chiller plant. The cooling load contributes 45–60% of total power consumption in commercial and office buildings, especially at tropics. The chiller plant operation is not optimal in most of the existing buildings because the chiller plant is either operated at design condition irrespective of the cooling load or optimized locally due to lack of overall chiller plant behavior. In this study, an overall energy model of chiller plant is developed to capture the thermal behavior of all systems and their interactions including the power consumption. An energy optimization methodology is proposed to derive optimized operation decisions for chiller plant at regular intervals based on building thermal load and weather condition. The benefits of proposed energy optimization methodology are examined using case study problems covering different chiller plant configurations. The case studies result confirmed the energy savings achieved through optimized operations is up to 40% for moderate size chiller plant and around 20% for small chiller plant which consequently reduces the energy cost and greenhouse gas emissions. - Highlights: • Energy optimization methodology improves the performance of multi-chiller plant. • Overall energy model of chiller plant accounts all equipment and the interactions. • Operation decisions are derived at regular interval based on time-varying factors. • Three case studies confirmed 20 to 40% of energy savings than conventional method.

  12. Variable-Speed Screw Chiller, Sidney Yates Building, Washington, DC

    Energy Technology Data Exchange (ETDEWEB)

    Ostrouchov, George [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Adams, Mark B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howett, Daniel H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-07-01

    This report captures the findings from an evaluation ORNL performed on a new chiller technology as part of GSA's Proving Ground Program. Note: Appendices B&C were removed from this report while the author looks for a way to insert them without consuming over 200MB of file size.

  13. Analysis and parameter identification for characteristic equations of single- and double-effect absorption chillers by means of multivariable regression

    DEFF Research Database (Denmark)

    Puig Arnavat, Maria; López-Villada, Jesús; Bruno, Joan Carles

    2010-01-01

    Two approaches to the characteristic equation method have been compared in order to find a simple model that best describes the performance of thermal chillers. After comparing the results obtained using experimental data from a single-effect absorption chiller, we concluded that the adaptation o...... chillers. The characteristic parameters for these chillers are given and can be incorporated as a chiller module in thermal modelling and simulation packages....

  14. Detection of polar vapours

    International Nuclear Information System (INIS)

    Blyth, D.A.

    1980-01-01

    Apparatus for monitoring for polar vapours in a gas consists of (i) a body member defining a passage through which a continuous stream of the gas passes; (ii) an ionising source associated with a region of the passage such that ionization of the gas stream takes place substantially only within the region and also any polar vapour molecules present therein will react with the gas formed to generate ion clusters; and (iii) an electrode for collecting ions carried by the gas stream, the electrode being positioned in the passage downstream of the region and separated from the region by a sufficient distance to ensure that no substantial number of the gas ions formed in said region remains in the gas stream at the collector electrode whilst ensuring that a substantial proportion of the ion clusters formed in the region does remain in the gas stream at the collector electrode. (author)

  15. Vapour pressure of trideuterioammonia

    Energy Technology Data Exchange (ETDEWEB)

    Calado, J.C.G.; Lopes, J.N.C.; Rebelo, L.P.N. (Instituto Superior Tecnico, Lisbon (Portugal). Centro de Quimica Estrutural)

    1992-09-01

    The H-to-D vapour-pressure isotope effect in liquid ammonia has been measured at 62 temperatures between 228 K and 260 K. The vapour pressures, corrected to 100 per cent nuclidic purity, have been fitted to the equation: T ln r = A+B/T+CT, where r is the vapour-pressure ratio p(NH[sub 3])/p(ND[sub 3]). The fit yielded the parameters: A = -8.22508 K, B = 12338.2 K[sup 2], and C = -0.05544. Comparisons with the results of other authors were made in order to clarify some discrepancies found in the literature. Our values are in accord with the previous results of King et al. and an extrapolation of the fitted equation down to the triple-point temperature gave good agreement with the published results. The fitted equation was used in conjunction with the Clapeyron equation to calculate the difference in the molar enthalpies of vaporization between NH[sub 3] and ND[sub 3]. At T = 230 K that difference is -846 J.mol[sup -1] decreasing to -747 J.mol[sup -1] at 260 K. (author).

  16. Evolution strategy based optimal chiller loading for saving energy

    International Nuclear Information System (INIS)

    Chang, Y.-C.; Lee, C.-Y.; Chen, C.-R.; Chou, C.-J.; Chen, W.-H.; Chen, W.-H.

    2009-01-01

    This study employs evolution strategy (ES) to solve optimal chiller loading (OCL) problem. ES overcomes the flaw that Lagrangian method is not adaptable for solving OCL as the power consumption models or the kW-PLR (partial load ratio) curves include convex functions and concave functions simultaneously. The complicated process of evolution by the genetic algorithm (GA) method for solving OCL can also be simplified by the ES method. This study uses the PLR of chiller as the variable to be solved for the decoupled air conditioning system. After analysis and comparison of the case study, it has been concluded that this method not only solves the problems of Lagrangian method and GA method, but also produces results with high accuracy within a rapid timeframe. It can be perfectly applied to the operation of air conditioning systems

  17. Performance Analysis of Waste Heat Driven Pressurized Adsorption Chiller

    KAUST Repository

    LOH, Wai Soong

    2010-01-01

    This article presents the transient modeling and performance of waste heat driven pressurized adsorption chillers for refrigeration at subzero applications. This innovative adsorption chiller employs pitch-based activated carbon of type Maxsorb III (adsorbent) with refrigerant R134a as the adsorbent-adsorbate pair. It consists of an evaporator, a condenser and two adsorber/desorber beds, and it utilizes a low-grade heat source to power the batch-operated cycle. The ranges of heat source temperatures are between 55 to 90°C whilst the cooling water temperature needed to reject heat is at 30°C. A parametric analysis is presented in the study where the effects of inlet temperature, adsorption/desorption cycle time and switching time on the system performance are reported in terms of cooling capacity and coefficient of performance. © 2010 by JSME.

  18. Thermodynamic feasibility of harvesting data center waste heat to drive an absorption chiller

    International Nuclear Information System (INIS)

    Haywood, Anna; Sherbeck, Jon; Phelan, Patrick; Varsamopoulos, Georgios; Gupta, Sandeep K.S.

    2012-01-01

    Highlights: ► We propose an alternative data center cooling architecture that is heat driven. ► Our primary source of thermal energy is the heat dissipated by the CPUs. ► Supplementary external heat sources such as solar thermal are included as well. ► We develop a comprehensive model that leads to a potentially realizable value of less than one. - Abstract: More than half the energy to run a data center can be consumed by vapor-compression equipment that cools the center. To reduce consumption and recycle otherwise wasted thermal energy, this paper proposes an alternative cooling architecture that is heat driven and leads to a more efficient data center in terms of power usage effectiveness (PUE). The primary thermal source is waste heat produced by CPUs on each server blade. The main challenge is capturing enough of this high-temperature heat to energize an absorption unit. The goal is to capture a high fraction of dissipated thermal power by using a heat capture scheme with water as the heat transfer fluid. To determine if the CPU temperature range and amount of heat are sufficient for chiller operation, we use server software, validation thermocouples, and chip specifications. We compare these results to required values from a simulator tool specific to our chiller model. One challenge is to simultaneously cool the data center and generate enough exergy to drive the cooling process, regardless of the thermal output of the data center equipment. We can address this by adding phase change latent heat storage to consistently deliver the required heat flow and, if necessary, a solar heat source. Even with zero solar contribution, the results show that the number of CPUs we have is sufficient and our PUE indicates a very efficient data center. Adding solar contribution, the steady-state model proposed leads to a potentially realizable PUE value of less than one.

  19. Study on Relative COP Changes with Increasing Heat Input Temperatures of Double Effect Steam Absorption Chillers

    Directory of Open Access Journals (Sweden)

    Abd Majid Mohd Amin

    2016-01-01

    Full Text Available Absorption chillers at cogeneration plants generate chilled water using steam supplied by heat recovery steam generators. The chillers are mainly of double effect type. The COP of double effect varies from 0.7 to 1.2 depending on operation and maintenance practices of the chillers. Heat input to the chillers during operations could have impact on the COP of the chillers. This study is on relative COP changes with increasing the heat input temperatures for a steam absorption chiller at a gas fueled cogeneration plant. Reversible COP analysis and zero order model were used for evaluating COP of the chiller for 118 days operation period. Results indicate increasing COP trends for both the reversible COP and zero model COP. Although the zero model COP are within the range of double effect absorption chiller, it is not so for the actual COP. The actual COP is below the range of normal double effect COP. It is recommended that economic replacement analysis to be undertaken to assess the feasibility either to repair or replace the existing absorption chiller.

  20. Aging assessment of essential HVAC chillers used in nuclear power plants

    International Nuclear Information System (INIS)

    Blahnik, D.E.; Camp, T.W.

    1996-09-01

    The Pacific Northwest Laboratory conducted a comprehensive aging assessment of chillers used in the essential safety air-conditioning systems in nuclear power plants (NPPs). The chillers used, and air-conditioning systems served, vary in design from plant to plant. The review of operating experience indicated that chillers experience aging degradation and failures. The primary aging factors of concern for chillers include vibration, excessive temperatures and pressures, thermal cycling, chemical attack, and poor quality cooling water. The evaluation of Licensee Event Reports (LERs) indicated that about 38% of the failures were primarily related to aging, 55% were partially aging related, and 7% of the failures were unassignable. About 25% of the failures were primarily caused by human, design, procedure, and other errors. The large number of errors is probably directly related to the complexity of chillers and their interfacing systems. Nearly all of the LERs were the result of entering plant Technical Specification Limiting Condition for Operation (LCO) that initiated remedial actions like plant shutdown procedures. The trend for chiller-related LERs has stabilized at about 0.13 LERs per plant year since 1988. Carefully following the vendor procedures and monitoring the equipment can help to minimize and/or eliminate most of the premature failures. Recording equipment performance can be useful for trending analysis. Periodic operation for a few hours on a weekly or monthly basis is useful to remove moisture and non-condensable gases that gradually build up inside the chiller. Chiller pressurization kits are available that will help minimize the amount of moisture and air ingress to low-pressure chillers during standby periods. The assessment of service life condition monitoring of chillers indicated there are many simple to sophisticated methods available that can help in chiller surveillance and monitoring

  1. Aging assessment of essential HVAC chillers used in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Blahnik, D.E.; Camp, T.W.

    1996-09-01

    The Pacific Northwest Laboratory conducted a comprehensive aging assessment of chillers used in the essential safety air-conditioning systems in nuclear power plants (NPPs). The chillers used, and air-conditioning systems served, vary in design from plant to plant. The review of operating experience indicated that chillers experience aging degradation and failures. The primary aging factors of concern for chillers include vibration, excessive temperatures and pressures, thermal cycling, chemical attack, and poor quality cooling water. The evaluation of Licensee Event Reports (LERs) indicated that about 38% of the failures were primarily related to aging, 55% were partially aging related, and 7% of the failures were unassignable. About 25% of the failures were primarily caused by human, design, procedure, and other errors. The large number of errors is probably directly related to the complexity of chillers and their interfacing systems. Nearly all of the LERs were the result of entering plant Technical Specification Limiting Condition for Operation (LCO) that initiated remedial actions like plant shutdown procedures. The trend for chiller-related LERs has stabilized at about 0.13 LERs per plant year since 1988. Carefully following the vendor procedures and monitoring the equipment can help to minimize and/or eliminate most of the premature failures. Recording equipment performance can be useful for trending analysis. Periodic operation for a few hours on a weekly or monthly basis is useful to remove moisture and non-condensable gases that gradually build up inside the chiller. Chiller pressurization kits are available that will help minimize the amount of moisture and air ingress to low-pressure chillers during standby periods. The assessment of service life condition monitoring of chillers indicated there are many simple to sophisticated methods available that can help in chiller surveillance and monitoring.

  2. Experimental study on improved two-bed silica gel-water adsorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Xia Zaizhong [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200030 (China)], E-mail: xzz@sjtu.edu.cn; Wang Dechang; Zhang Jincui [College of Electromechanical Engineering, Qingdao University, Qingdao 266071 (China)

    2008-06-15

    A novel silica gel-water adsorption chiller with two chambers has been built in Shanghai Jiao Tong University (SJTU). This chiller combines two single bed systems (basic system) without any vacuum valves. One adsorber, one condenser and one evaporator are housed in the same chamber to constitute one adsorption/desorption unit. In this work, the chiller is developed and improved. The improved chiller is composed of three vacuum chambers: two adsorption/desorption vacuum chambers (the same structure as the former chiller) and one heat pipe working vacuum chamber. The evaporators of these two adsorption/desorption units are combined by a heat pipe. So, no valves are installed in the chilled water sub system and one vacuum valve connects the two adsorption/desorption chambers together to improve its performance. The performance of the chiller is tested. As the results, the refrigerating capacity and the COP of the chiller are, respectively, 8.69 kW and 0.388 for the heat source temperature of 82.5 deg. C, the cooling water temperature of 30.4 deg. C and the chilled water outlet temperature of 11.9 deg. C. For a chilled water outlet temperature of 16.5 deg. C, the COP reaches 0.432, while the refrigerating capacity is near 11 kW. There is an improvement of at least 12% for the COP compared with the former chillers.

  3. Experimental study on improved two-bed silica gel-water adsorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zaizhong [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200030 (China); Wang, Dechang; Zhang, Jincui [College of Electromechanical Engineering, Qingdao University, Qingdao 266071 (China)

    2008-06-15

    A novel silica gel-water adsorption chiller with two chambers has been built in Shanghai Jiao Tong University (SJTU). This chiller combines two single bed systems (basic system) without any vacuum valves. One adsorber, one condenser and one evaporator are housed in the same chamber to constitute one adsorption/desorption unit. In this work, the chiller is developed and improved. The improved chiller is composed of three vacuum chambers: two adsorption/desorption vacuum chambers (the same structure as the former chiller) and one heat pipe working vacuum chamber. The evaporators of these two adsorption/desorption units are combined by a heat pipe. So, no valves are installed in the chilled water sub system and one vacuum valve connects the two adsorption/desorption chambers together to improve its performance. The performance of the chiller is tested. As the results, the refrigerating capacity and the COP of the chiller are, respectively, 8.69 kW and 0.388 for the heat source temperature of 82.5 C, the cooling water temperature of 30.4 C and the chilled water outlet temperature of 11.9 C. For a chilled water outlet temperature of 16.5 C, the COP reaches 0.432, while the refrigerating capacity is near 11 kW. There is an improvement of at least 12% for the COP compared with the former chillers. (author)

  4. Constraints of using thermostatic expansion valves to operate air-cooled chillers at lower condensing temperatures

    International Nuclear Information System (INIS)

    Yu, F.W.; Chan, K.T.; Chu, H.Y.

    2006-01-01

    Thermostatic expansion valves (TXVs) have long been used in air-cooled chillers to implement head pressure control under which the condensing temperature is kept high at around 50 o C by staging condenser fans as few as possible. This paper considers how TXVs prevent the chillers from operating with an increased COP at lower condensing temperatures when the chiller load or outdoor temperature drops. An analysis on an existing air-cooled reciprocating chiller showed that the range of differential pressures across TXVs restricts the maximum heat rejection airflow required to increase the chiller COP, though the set point of condensing temperature is reduced to 22 o C from a high level of 45 o C. It is possible to use electronic expansion valves to meet the differential pressure requirements for maximum chiller COP. There is a maximum of 28.7% increase in the chiller COP when the heat rejection airflow is able to be maximized in various operating conditions. The results of this paper emphasize criteria for lowering the condensing temperature to enhance the performance of air-cooled chillers

  5. Aging assessment of essential HVAC chillers used in nuclear power plants

    International Nuclear Information System (INIS)

    Blahnik, D.E.; Klein, R.F.

    1993-09-01

    The Pacific Northwest Laboratory conducted a Phase I aging assessment of chillers used in the essential safety air-conditioning systems of nuclear power plants. Centrifugal chillers in the 75- to 750-ton refrigeration capacity range are the predominant type used. The chillers used, and air-conditioning systems served, vary in design from plant-to-plant. It is crucial to keep chiller internals very clean and to prevent the leakage of water, air, and other contaminants into the refrigerant containment system. Periodic operation on a weekly or monthly basis is necessary to remove moisture and noncondensable gases that gradually build up inside the chiller. This is especially desirable if a chiller is required to operate only as an emergency standby unit. The primary stressors and aging mechanisms that affect chillers include vibration, excessive temperatures and pressures, thermal cycling, chemical attack, and poor quality cooling water. Aging is accelerated by moisture, non-condensable gases (e.g., air), dirt, and other contamination within the refrigerant containment system, excessive start/stop cycling, and operating below the rated capacity. Aging is also accelerated by corrosion and fouling of the condenser and evaporator tubes. The principal cause of chiller failures is lack of adequate monitoring. Lack of performing scheduled maintenance and human errors also contribute to failures

  6. Aging assessment of essential HVAC chillers used in nuclear power plants. Phase 1, Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Blahnik, D.E.; Klein, R.F. [Pacific Northwest Lab., Richland, WA (United States)

    1993-09-01

    The Pacific Northwest Laboratory conducted a Phase I aging assessment of chillers used in the essential safety air-conditioning systems of nuclear power plants. Centrifugal chillers in the 75- to 750-ton refrigeration capacity range are the predominant type used. The chillers used, and air-conditioning systems served, vary in design from plant-to-plant. It is crucial to keep chiller internals very clean and to prevent the leakage of water, air, and other contaminants into the refrigerant containment system. Periodic operation on a weekly or monthly basis is necessary to remove moisture and noncondensable gases that gradually build up inside the chiller. This is especially desirable if a chiller is required to operate only as an emergency standby unit. The primary stressors and aging mechanisms that affect chillers include vibration, excessive temperatures and pressures, thermal cycling, chemical attack, and poor quality cooling water. Aging is accelerated by moisture, non-condensable gases (e.g., air), dirt, and other contamination within the refrigerant containment system, excessive start/stop cycling, and operating below the rated capacity. Aging is also accelerated by corrosion and fouling of the condenser and evaporator tubes. The principal cause of chiller failures is lack of adequate monitoring. Lack of performing scheduled maintenance and human errors also contribute to failures.

  7. Part load performance of air-cooled centrifugal chillers with variable speed condenser fan control

    Energy Technology Data Exchange (ETDEWEB)

    Yu, F.W.; Chan, K.T. [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2007-11-15

    Air-cooled centrifugal chillers are commonly used in commercial buildings but their performance analysis is lacking. This paper investigates the part load performance of the chillers via a thermodynamic model. The model was validated using a wide range of operating data from an existing chiller with specific settings of outdoor temperature and condensing pressure in controlling the condensing temperature. The validated model was developed specifically to ascertain the maximum coefficient of performance of chiller (COP) together with the strategy for optimizing the condensing temperature under various operating conditions. It is found that the highest COP occurs at a part load ratio (PLR) of 0.71-0.84, depending on the outdoor temperature and the control of condensing temperature, rather than at full load. Yet the chillers operating at such part load conditions will cause extra energy used for the early staging of chilled water pumps. To minimize the overall chiller plant energy consumption, it is still preferable to implement chiller sequencing based on the full load condition than on the aforementioned PLRs. The results of this paper present criteria for implementing low-energy strategies for operating air-cooled chillers satisfying a given building cooling load profile. (author)

  8. ANALISA KINERJA REFRIGERASI WATER CHILLER PADA PT GMF AEROASIA

    Directory of Open Access Journals (Sweden)

    Ali Nugroho

    2015-02-01

    Full Text Available Pengkondisian udara merupakan salah satu hal yang paling penting dalam suatu industri atau gedung, khusunya pada suatu gedung perkantoran. Karena dengan sistem pengkondisian udara yang baik akan menghasilkan uadara segar yang akan memperoleh kenyamanan bagi manusia, mesin, maupun lingkungan yang berada disekitar. Karena dengan tingkat kenyamanan yang baik akan meningkatkan kinerja dari mesin yang digunakan. Ketidak sesuaian pola pengoperasian sistem refrigerai pada saat perancangan dengan keadaan aktual merupakan salah satu penyebab tingginya konsumsi energi listrik, oleh karena itu perlu dilakukan analisa performansi pada sistem refrigerasi di sana agar dapat diketahui apakah energi yang digunakan sudah efisien. Untuk menganalisia kinerja mesin water chiller ini dilakukan dengan pengamatan langsung terhadap panel control water chiller selama empat jam sekali secara continue selama lima hari. Dan dilakukan perhitungan dari data tersebut untuk mengetahui nilai effisiensinya yaitu: COP, laju aliran refrigerant, kalor yang diserap evaporator dan kondensor, kerja yang dilakukan kompresor, daya yang dibutuhkan kompresor, dan laju aliran volume air cooling water. Kinerja chiller yang baik mempunyai efisiensi yang dapat dipengaruhi antara lain oleh: temperatur air keluar evaporator, dan temperaturr air masuk kondensor. Hasil penelitian hari sabtu diperoleh nilai COP = 8,04, Pref = 0,44 kW/TR, TR = 112,961 TR, dan laju massa refrigerant evaporator = 2,415 kg/s, kerja yang dilakukan kompresor = 49,395kW, laju aliran volume cooling tower = 94,613 m3/jam, dan laju aliran volume make-up water = 0,567 m3/jam. Maka di simpulkan semakin rendah temperatur refrigerant di kondensor maka akan semakin bagus juga nilai COP yang dihasilkan(KW/TR semakin rendah, karena kerja kompresor yang dibutuhkan akan lebih rendah.

  9. Targeting Zero Emission Through Siemens Compressor Chiller Packages

    Energy Technology Data Exchange (ETDEWEB)

    Girbig, Paul

    2010-09-15

    Ecological as well as economic impacts necessities in District Cooling Technology. Reduction of total primary energy use. Reduction of greenhouse gas emission. Energy efficiency goals worldwide and in chiller equipment. A smart grid to get a reliable energy supply. Use of the sun leads to thermal power plants. Thermal storage technology to compensate differences in load and supply. The high energy demand of the district cooling plants, the variety of load demand, the methods employed in production of refrigeration and the highly sensitive production processes, depend on a reliable and efficient supply of technology.

  10. Central magnetic cooling and refrigeration machines (chiller) and their assessment. A feasibility study - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Egolf, P. W.; Gonin, C. [University of Applied Sciences of Western Switzerland, HEIG-VD, Yverdon-les Bains (Switzerland); Kitanovski, A. [University of Ljubljana, Ljubljana (Slovenia)

    2010-03-15

    This final report for the Swiss Federal Office of Energy (SFOE) presents the results of a feasibility study made concerning magnetic cooling and refrigeration machines. This report presents a comprehensive thermodynamic and economic analysis of applications of rotary magnetic chillers. The study deals with magnetic chillers based on permanent magnets and superconducting magnets, respectively. The numerical design of permanent magnet assemblies with different magnetic flux densities is discussed. The authors note that superconducting magnetic chillers are feasible only in large-scale applications with over 1 MW of cooling power. This report describes new ideas for magnetic refrigeration technologies, which go beyond the state of the art. They show potential for a substantial reduction of costs and further improvements in efficiency. Rotary magnetic liquid chillers with 'wavy' structures and using micro tubes are discussed, as are superconducting magnetic chillers and future magneto-caloric technologies.

  11. The effects of operation parameter on the performance of a solar-powered adsorption chiller

    International Nuclear Information System (INIS)

    Luo, Huilong; Wang, Ruzhu; Dai, Yanjun

    2010-01-01

    A solar-powered adsorption chiller with heat and mass recovery cycle was designed and constructed. It consists of a solar water heating unit, a silica gel-water adsorption chiller, a cooling tower and a fan coil unit. The adsorption chiller includes two identical adsorption units and a second stage evaporator with methanol working fluid. The effects of operation parameter on system performance were tested successfully. Test results indicated that the COP (coefficient of performance) and cooling power of the solar-powered adsorption chiller could be improved greatly by optimizing the key operation parameters, such as solar hot water temperature, heating/cooling time, mass recovery time, and chilled water temperature. Under the climatic conditions of daily solar radiation being about 16-21 MJ/m 2 , this solar-powered adsorption chiller can produce a cooling capacity about 66-90 W per m 2 collector area, its daily solar cooling COP is about 0.1-0.13.

  12. A Tunable Bimetallic MOF-74 for Adsorption Chiller Applications: A Tunable Bimetallic MOF-74 for Adsorption Chiller Applications

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jian [Pacific Northwest National Laboratory, 99352 Richland WA USA; Zheng, Jian [Pacific Northwest National Laboratory, 99352 Richland WA USA; Barpaga, Dushyant [Pacific Northwest National Laboratory, 99352 Richland WA USA; Sabale, Sandip [Pacific Northwest National Laboratory, 99352 Richland WA USA; P.G. Department of Chemistry, Jaysingpur College, 416101 Jaysingpur Maharashtra India; Arey, Bruce [Environmental Molecular Sciences Laboratory (EMSL), Pacific Northwest National Laboratory, 99352 Richland WA USA; Derewinski, Miroslaw A. [Pacific Northwest National Laboratory, 99352 Richland WA USA; McGrail, B. Peter [Pacific Northwest National Laboratory, 99352 Richland WA USA; Motkuri, Radha Kishan [Pacific Northwest National Laboratory, 99352 Richland WA USA

    2018-02-12

    A mixed metal strategy, in which two different metal nodes coexist in one MOF framework, was examined using MOF-74. The Ni salt precursor for the MOF-74(Ni) analogue was partially replaced during synthesis with relatively inexpensive Zn salt. These bimetallic MOFs were developed and examined for water sorption for potential use in adsorption cooling/chiller applications. Varying concentration ratios of Ni:Zn in MOF-74 achieved using this mixed metal strategy were shown to provide unique impacts on H2O uptake while significantly mitigating the costs of synthesis

  13. Absorber performance of a water/lithium-bromide absorption chiller

    International Nuclear Information System (INIS)

    Xie Guozhen; Sheng Guogang; Bansal, Pradeep Kumar; Li, Guang

    2008-01-01

    An absorber is one of the most important components of a lithium-bromide absorption chiller (LBAC) as its absorbing characteristics directly influence the performance of the whole chiller. It has been indicated that the absorbing efficiency and cooling capacity could be improved by increasing the solution concentration. In this paper, based on the mechanism of falling film absorption on horizontal tubes, the theoretical models of falling film absorption on horizontal tubes have been established. A series of programs used for computing the theoretical mathematical models, including simulation of LBAC cycle and falling film absorption, have been programmed. The models have been validated reasonably by the experimental data. The results show that the cooling capacity of the LBAC varies in parabola shape of curve with the solution concentration from 52.5% to 58.5%, and that the best coefficient of performance (COP) occurs at concentration of 57%. The investigation proposes the absorbing process of sub-steady thermodynamic equilibrium for the duality solution under increase absorbing pressure

  14. Experimental research on novel adsorption chiller driven by low grade heat source

    International Nuclear Information System (INIS)

    Wang, D.C.; Shi, Z.X.; Yang, Q.R.; Tian, X.L.; Zhang, J.C.; Wu, J.Y.

    2007-01-01

    A novel silica gel-water adsorption chiller is developed. This chiller consists of three vacuum chambers: two adsorption/desorption (or evaporation/condensation) vacuum chambers and one heat pipe working vacuum chamber. In this chiller, only one vacuum valve is installed between the two adsorption/desorption vacuum chambers to improve its performance when it is driven by a low temperature heat source. The operational reliability of the chiller is highly improved because of fewer moving parts. In this work, the performance of the chiller is experimentally tested under a low grade heat source, such as 55-67 o C. The test results show that the performance of this chiller is satisfying when it is driven by a low grade heat source, such as 65 o C, and the cooling capacity (or refrigeration capacity) will reach about 5 kW when the hot water temperature is 65 o C, the cooling water temperature is 30.5 o C and the chilled water inlet temperature is 15.1 o C. The test results confirm that this kind of adsorption chiller can be effectively driven by a low grade heat source

  15. Improved condenser design and condenser-fan operation for air-cooled chillers

    International Nuclear Information System (INIS)

    Yu, F.W.; Chan, K.T.

    2006-01-01

    Air-cooled chillers traditionally operate under head pressure control via staging constant-speed condenser fans. This causes a significant drop in their coefficient of performance (COP) at part load or low outdoor temperatures. This paper describes how the COP of these chillers can be improved by a new condenser design, using evaporative pre-coolers and variable-speed fans. A thermodynamic model for an air-cooled screw-chiller was developed, within which the condenser component considers empirical equations showing the effectiveness of an evaporative pre-cooler in lowering the outdoor temperature in the heat-rejection process. The condenser component also contains an algorithm to determine the number and speed of the condenser fans staged at any given set point of condensing temperature. It is found that the chiller's COP can be maximized by adjusting the set point based on any given chiller load and wet-bulb temperature of the outdoor air. A 5.6-113.4% increase in chiller COP can be achieved from the new condenser design and condenser fan operation. This provides important insights into how to develop more energy-efficient air-cooled chillers

  16. Evaluation of Aqua-Ammonia Chiller Technologies and Field Site Installation

    Energy Technology Data Exchange (ETDEWEB)

    Zaltash, Abdolreza [ORNL

    2007-09-01

    The Naval Facilities Engineering Service Center (NFESC) has sponsored Oak Ridge National Laboratory (ORNL) to review, select, and evaluate advanced, gas-fired, 5-ton, aqua-ammonia, chiller technologies. The selection criteria was that units have COP values of 0.67 or better at Air-conditioning and Refrigeration Institute (ARI) 95 F outdoor rating conditions, an active refrigerant flow control, and a variable-speed condenser fan. These features are expected to allow these units to operate at higher ambient temperatures (up to the maximum operating temperature of 110 F) with minimal degradation in performance. ORNL evaluated three potential manufacturers of advanced, gas-fired, 5-ton, aqua-ammonia chillers-Robur, Ambian, and Cooling Technologies. Unfortunately, Robur did not meet the COP requirements and Cooling Technologies could not deliver a unit to be tested at the U.S. Department of Energy (DOE)-ORNL environmental chamber testing facility for thermally activated heat pumps. This eliminated these two technologies from further consideration, leaving only the Ambian chillers for evaluation. Two Ambian chillers were evaluated at the DOE-ORNL test facility. Overall these chillers operated well over a wide range of ambient conditions with minimal degradation in performance due to several control strategies used such as a variable speed condenser fan, a modulating burner, and active refrigerant flow control. These Ambian pre-commercial units were selected for installation and field testing at three federal facilities. NFESC worked with ORNL to assist with the site selection for installation and evaluation of these chillers. Two sites (ORNL and Naval Surface Warfare Center [NSWC] Corona) had a single chiller unit installed; and at one site (Naval Amphibious Base [NAB] Little Creek), two 5-ton chillers linked together were installed to provide 10 tons of cooling. A chiller link controller developed under this project was evaluated in the field test at Little Creek.

  17. Corrosion behavior of selected materials in lithium bromide solution for the application absorption chillers; Korrosionsverhalten ausgewaehlter Werkstoffe in Lithiumbromid-Loesung fuer den Anwendungsfall Absorptionskaeltemaschinen

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, B. [ZAE Bayern, Garching (Germany)

    2004-07-01

    Absorption chillers on the basis of lithium bromide-water are interesting systems for efficient and energy-saving supply of coldness. The heating energy for the propulsion of the chiller could result ideally from renewable energies, e.g. solar energy, or waste heating energy from industry. The chiller can work as a multiple-stage process for increasing the energy efficiency. For the three-stage-plants, in the generator temperatures of up to 200-220 C are necessary. The factors high temperature, high halogenide concentration (lithium bromide) and the presence of water vapour lead to a very high corrosive exposure of the materials. In that reason the task of the present report was the consideration of commercial materials and inhibitors concerning their suitability for the application in triple-effect-chillers. The measurements were carried out under identical conditions, but in unmoved solution and excluding the contact with air. The result of the investigations showed that stainless steel has been identified as a promising material for this application. Furthermore we have found out that the type of the inhibitor and the interaction of different phases have a strong influence on the corrosion processes. (Abstract Copyright [2004], Wiley Periodicals, Inc.) [German] Absorptionskaeltemaschinen auf der Basis von Lithiumbromid-Wasser stellen eine interessante Moeglichkeit zur effizienten und energiesparenden Versorgung mit Kaelte dar. Die zum Antrieb erforderliche Waermeenergie kann idealerweise aus regenerativen Energien, wie z.B. Solarwaerme, oder Abwaerme aus der Industrie bereitgestellt werden. Um die Energieeffizienz zu steigern, koennen die Prozesse mehrstufig betrieben werden. Bei den dreistufigen, sogenannten Triple-Effekt-Anlagen, sind im Generator Temperaturen bis zu etwa 200-220 C erforderlich. Die Faktoren hohe Temperatur, hohe Halogenidkonzentration (Lithiumbromid) und die Anwesenheit von Wasserdampf fuehren zu einer besonders starken korrosiven

  18. Optimal chiller sequencing by branch and bound method for saving energy

    International Nuclear Information System (INIS)

    Chang, Y.-C.; Lin, F.-A.; Lin, C.H.

    2005-01-01

    This paper proposes a method for using the branch and bound (B and B) method to solve the optimal chiller sequencing (OCS) problem and to eliminate the deficiencies of conventional methods. The coefficient of performance (COP) of the chiller is adopted as the objective function because it is concave. The Lagrangian method determines the optimal chiller loading (OCL) in each feasible state. The potential performance of the proposed method is examined with reference to an example system. The proposed method consumes much less power than the conventional method and is very appropriate for application in air conditioning systems

  19. Economical analysis of combined fuel cell generators and absorption chillers

    Directory of Open Access Journals (Sweden)

    M. Morsy El-Gohary

    2013-06-01

    Full Text Available This paper presents a co-generation system based on combined heat and power for commercial units. For installation of a co-generation system, certain estimates for this site should be performed through making assessments of electrical loads, domestic water, and thermal demand. This includes domestic hot water, selection of the type of power generator, fuel cell, and the type of air conditioning system, and absorption chillers. As a matter of fact, the co-generation system has demonstrated good results for both major aspects, economic and environmental. From the environmental point of view, this can be considered as an ideal solution for problems concerned with the usage of Chlorofluoro carbons. On the other hand, from the economic point of view, the cost analysis has revealed that the proposed system saves 4% of total cost through using the co-generation system.

  20. Test Ability of Chiller Post Re-functioning at The Facility of KH-IPSB3

    International Nuclear Information System (INIS)

    Harahap, Sentot-Alibasya; M-Taufik-Arsyad; Djunaidi

    2006-01-01

    Chiller water unit (CWU) represent supplier of cool water for the system of ventilation, cooler of purification system irrigate canal (T.C) and pool (depository ponds) ex-fuel at facility of KH-IPSB3. Have been conducted by re-functioning of Chiller unit water by changing system conduct and control from electronic mode to mode of electric-mechanic and parts of damage other. A unit water chiller system have some component / appliance which way of its activity integrated one other, so that re-functioning of partial like in this time where some of component / appliance use old goods and some of using new material hence to get optimum activity at test ability of difficult chiller relative. At operation is old ones expected by optimum activity will be able to reach with an process which in phases and planed. (author)

  1. Integration of a molten carbonate fuel cell with a direct exhaust absorption chiller

    Science.gov (United States)

    Margalef, Pere; Samuelsen, Scott

    A high market value exists for an integrated high-temperature fuel cell-absorption chiller product throughout the world. While high-temperature, molten carbonate fuel cells are being commercially deployed with combined heat and power (CHP) and absorption chillers are being commercially deployed with heat engines, the energy efficiency and environmental attributes of an integrated high-temperature fuel cell-absorption chiller product are singularly attractive for the emerging distributed generation (DG) combined cooling, heating, and power (CCHP) market. This study addresses the potential of cooling production by recovering and porting the thermal energy from the exhaust gas of a high-temperature fuel cell (HTFC) to a thermally activated absorption chiller. To assess the practical opportunity of serving an early DG-CCHP market, a commercially available direct fired double-effect absorption chiller is selected that closely matches the exhaust flow and temperature of a commercially available HTFC. Both components are individually modeled, and the models are then coupled to evaluate the potential of a DG-CCHP system. Simulation results show that a commercial molten carbonate fuel cell generating 300 kW of electricity can be effectively coupled with a commercial 40 refrigeration ton (RT) absorption chiller. While the match between the two "off the shelf" units is close and the simulation results are encouraging, the match is not ideal. In particular, the fuel cell exhaust gas temperature is higher than the inlet temperature specified for the chiller and the exhaust flow rate is not sufficient to achieve the potential heat recovery within the chiller heat exchanger. To address these challenges, the study evaluates two strategies: (1) blending the fuel cell exhaust gas with ambient air, and (2) mixing the fuel cell exhaust gases with a fraction of the chiller exhaust gas. Both cases are shown to be viable and result in a temperature drop and flow rate increase of the

  2. Integration of a molten carbonate fuel cell with a direct exhaust absorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Margalef, Pere; Samuelsen, Scott [National Fuel Cell Research Center (NFCRC), University of California, Irvine, CA 92697-3550 (United States)

    2010-09-01

    A high market value exists for an integrated high-temperature fuel cell-absorption chiller product throughout the world. While high-temperature, molten carbonate fuel cells are being commercially deployed with combined heat and power (CHP) and absorption chillers are being commercially deployed with heat engines, the energy efficiency and environmental attributes of an integrated high-temperature fuel cell-absorption chiller product are singularly attractive for the emerging distributed generation (DG) combined cooling, heating, and power (CCHP) market. This study addresses the potential of cooling production by recovering and porting the thermal energy from the exhaust gas of a high-temperature fuel cell (HTFC) to a thermally activated absorption chiller. To assess the practical opportunity of serving an early DG-CCHP market, a commercially available direct fired double-effect absorption chiller is selected that closely matches the exhaust flow and temperature of a commercially available HTFC. Both components are individually modeled, and the models are then coupled to evaluate the potential of a DG-CCHP system. Simulation results show that a commercial molten carbonate fuel cell generating 300 kW of electricity can be effectively coupled with a commercial 40 refrigeration ton (RT) absorption chiller. While the match between the two ''off the shelf'' units is close and the simulation results are encouraging, the match is not ideal. In particular, the fuel cell exhaust gas temperature is higher than the inlet temperature specified for the chiller and the exhaust flow rate is not sufficient to achieve the potential heat recovery within the chiller heat exchanger. To address these challenges, the study evaluates two strategies: (1) blending the fuel cell exhaust gas with ambient air, and (2) mixing the fuel cell exhaust gases with a fraction of the chiller exhaust gas. Both cases are shown to be viable and result in a temperature drop and flow

  3. Experimental determination of the energy efficiency of an air-cooled chiller under part load conditions

    International Nuclear Information System (INIS)

    Yu, F.W.; Chan, K.T.

    2005-01-01

    In cities located in a subtropical climate, air-cooled chillers are commonly used to provide cooling to the indoor environment. This accounts for the increasing electricity demand of buildings over the decades. This paper investigates how the condensing temperature serves to accurately determine the energy efficiency, or coefficient of performance (COP), of air-cooled chillers under part load conditions. An experiment on an air-cooled reciprocating chiller showed that for any given operating condition, the COP of the chiller varies, depending on how the condensing temperature is controlled. A sensitivity analysis is implemented to investigate to what extent COP is responding to changes in operating variables and confirms that the condensing temperature is an adequate variable to gauge COP under various operating conditions. The specifications of the upper limit for the condensing temperature in order to improve the energy efficiency of air-cooled chillers are discussed. The results of this work will give designers and researchers a good idea about how to model chiller energy performance curves in the thermal and energy computation exercises

  4. An experimental and analytical investigation of water chillers of nuclear power plant

    International Nuclear Information System (INIS)

    Wang Chunming

    2005-01-01

    Water chillers are important components of the electric building chilled water system of Nuclear Power Plant. In this article, we describe the seismic qualification methodology. A united method of seismic analysis and experiment testing were applied. Since the seismic classification of the evaporator, condenser and oil separator is 1F, the function criteria are necessary to be satisfied. The functional and performance of the control panel were qualified by seismic test. In order to get the seismic time histories of the base of the motor, compressor and control panel, we did time histories analysis for the whole chillers using the seismic acceleration time history of the building floor on which the water chillers was located. Then, these curves were translated into required response spectrum (RRS), which were used by the seismic test of water chillers compressor sets. All passive components, such as evaporator, condenser, oil separator and support, were qualified by seismic stress analysis method. These components were verified to satisfy the standard when they were subjected to the seismic, gravitational, operational pressure and nozzle loads. The Chillers' components were qualified to the specification and the standard. The motor-compressor set and control panel were qualified to the functional and performance criteria. The applied of this methodology adequately qualified the function of the water chillers compressor sets , especially after the aging test. (authors)

  5. Modelling of a condenser-fan control for an air-cooled centrifugal chiller

    International Nuclear Information System (INIS)

    Yu, F.W.; Chan, K.T.

    2007-01-01

    There is a lack of detailed experimental and simulation studies on air-cooled centrifugal chillers. This paper investigates how to optimize the control of condenser fans within the chillers to maximize their coefficients of performance (COPs). A thermodynamic model for the chillers was developed and used to analyse the steady-state COP under various load and ambient conditions. An algorithm is introduced to compute the number of staged condenser fans based on settings of the condensing pressure and outdoor temperature. The model was validated using the experimental data and performance data of an existing chiller running under various operating conditions. It is found that the best strategy for switching condenser fans is to vary their rotating speed by the use of a set point of the condensing temperature, which is adjusted in response to the chiller load and condenser air-inlet temperature. The results of this paper provide an important insight into how to increase the COPs of air-cooled chillers

  6. Modelling of a condenser-fan control for an air-cooled centrifugal chiller

    Energy Technology Data Exchange (ETDEWEB)

    Yu, F.W.; Chan, K.T. [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2007-11-15

    There is a lack of detailed experimental and simulation studies on air-cooled centrifugal chillers. This paper investigates how to optimize the control of condenser fans within the chillers to maximize their coefficients of performance (COPs). A thermodynamic model for the chillers was developed and used to analyse the steady-state COP under various load and ambient conditions. An algorithm is introduced to compute the number of staged condenser fans based on settings of the condensing pressure and outdoor temperature. The model was validated using the experimental data and performance data of an existing chiller running under various operating conditions. It is found that the best strategy for switching condenser fans is to vary their rotating speed by the use of a set point of the condensing temperature, which is adjusted in response to the chiller load and condenser air-inlet temperature. The results of this paper provide an important insight into how to increase the COPs of air-cooled chillers. (author)

  7. Improved energy performance of air cooled centrifugal chillers with variable chilled water flow

    International Nuclear Information System (INIS)

    Yu, F.W.; Chan, K.T.

    2008-01-01

    This paper considers how to apply optimum condensing temperature control and variable chilled water flow to increase the coefficient of performance (COP) of air cooled centrifugal chillers. A thermodynamic model for the chillers was developed and validated using a wide range of operating data and specifications. The model considers real process phenomena, including capacity control by the inlet guide vanes of the compressor and an algorithm to determine the number and speed of condenser fans staged based on a set point of condensing temperature. Based on the validated model, it was found that optimizing the control of condensing temperature and varying the evaporator's chilled water flow rate enable the COP to increase by 0.8-191.7%, depending on the load and ambient conditions. A cooling load profile of an office building in a subtropical climate was considered to assess the potential electricity savings resulting from the increased chiller COP and optimum staging of chillers and pumps. There is 16.3-21.0% reduction in the annual electricity consumption of the building's chiller plant. The results of this paper provide useful information on how to implement a low energy chiller plant

  8. Vapour Pressure of Diethyl Phthalate

    Czech Academy of Sciences Publication Activity Database

    Roháč, V.; Růžička, K.; Růžička, V.; Zaitsau, D. H.; Kabo, G. J.; Diky, V.; Aim, Karel

    2004-01-01

    Roč. 36, č. 11 (2004), s. 929-937 ISSN 0021-9614 Institutional research plan: CEZ:AV0Z4072921 Keywords : vapour pressure * diethyl phthalate * correlation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.144, year: 2004

  9. Unfired clay bricks – moisture properties and compressive strength

    DEFF Research Database (Denmark)

    Hansen, E.J. de Place; Hansen, Kurt Kielsgaard

    2002-01-01

    Apparatus, methods and test results from an experimental investigation of (1) the properties for moisture performance of the materials, including water vapour sorption and water vapour transmission, (2) humidity buffering of the indoor climate by an absorbent material, and (3) the compressive...... strength are presented....

  10. Thermodynamic simulation of condensation heat recovery characteristics of a single stage centrifugal chiller in a hotel

    International Nuclear Information System (INIS)

    Gong, Guangcai; Chen, Feihu; Su, Huan; Zhou, Jianyong

    2012-01-01

    Highlights: ► Thermodynamic model of a two-condenser condensation system has been carried out. ► Dynamic simulation method has been presented. ► COP and g of the refrigerating system is better than the single condensation system. ► The optimal parameters for the two-condenser condensation system have been studied. -- Abstract: A thermodynamic simulation study has been carried out for a single stage centrifugal chiller in this paper. The cooling capacity of the chiller unit is about 1750 kW. The chiller unit has been set and tested, and the work refrigerant is R22. A heat exchanger has been set between outlet of the compressor and the condenser for sanitary hot water supplying. Then the chiller unit is a kind of combined system that can provide sanitary hot water supplying and air conditioning simultaneously. A thermodynamic simulation model of the combined system has been established with the system simulation toolbox Simulink. Performance of the components and the combined system of the chiller unit has been studied over a wide range of operating conditions. The potential energy and fuel cost saving associated with the use of the proposed combined system for a typical hotel in south China has been estimated. It is showed that the combined system of the chiller unit is very useful in hotel buildings. And the thermodynamic simulation model of the combined system is significance for the optimization of parameters of the chiller unit such as condensation and evaporation temperature, mass flow of the sanitary hot water and size of hot water storage tank.

  11. Experimental investigation of a solar adsorption chiller used for grain depot cooling

    International Nuclear Information System (INIS)

    Luo, H.L.; Dai, Y.J.; Wang, R.Z.; Wu, J.Y.; Xu, Y.X.; Shen, J.M.

    2006-01-01

    The solar cooling technology is attractive since cooling load of building is roughly in phase with solar energy availability. In this study, a solar adsorption chiller was built and tested with aim of developing an alternative refrigeration system used for grain cooling storage. This solar adsorption chiller consists of four subsystems, namely, a solar water heating unit with 49.4 m 2 solar collecting area, a silica gel-water adsorption chiller, a cooling tower and a fan coil unit. In order to achieve continuous refrigeration, two adsorption units are operated out-of-phase with mass recovery cycle in the adsorption chiller. Field test results show that, under the climatic conditions of daily solar radiation being about 16-21 MJ/m 2 , this solar adsorption chiller can furnish 14-22 deg. C chilled air with an average cooling output ranging from about 3.2-4.4 kW, its daily solar cooling COP (coefficient of performance) is about 0.1-0.13

  12. LiCl Dehumidifier LiBr absorption chiller hybrid air conditioning system with energy recovery

    Science.gov (United States)

    Ko, Suk M.

    1980-01-01

    This invention relates to a hybrid air conditioning system that combines a solar powered LiCl dehumidifier with a LiBr absorption chiller. The desiccant dehumidifier removes the latent load by absorbing moisture from the air, and the sensible load is removed by the absorption chiller. The desiccant dehumidifier is coupled to a regenerator and the desiccant in the regenerator is heated by solar heated hot water to drive the moisture therefrom before being fed back to the dehumidifier. The heat of vaporization expended in the desiccant regenerator is recovered and used to partially preheat the driving fluid of the absorption chiller, thus substantially improving the overall COP of the hybrid system.

  13. A novel approach for optimal chiller loading using particle swarm optimization

    Energy Technology Data Exchange (ETDEWEB)

    Ardakani, A. Jahanbani; Ardakani, F. Fattahi; Hosseinian, S.H. [Department of Electrical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Avenue, Tehran 15875-4413 (Iran, Islamic Republic of)

    2008-07-01

    This study employs two new methods to solve optimal chiller loading (OCL) problem. These methods are continuous genetic algorithm (GA) and particle swarm optimization (PSO). Because of continuous nature of variables in OCL problem, continuous GA and PSO easily overcome deficiencies in other conventional optimization methods. Partial load ratio (PLR) of the chiller is chosen as the variable to be optimized and consumption power of the chiller is considered as fitness function. Both of these methods find the optimal solution while the equality constraint is exactly satisfied. Some of the major advantages of proposed approaches over other conventional methods can be mentioned as fast convergence, escaping from getting into local optima, simple implementation as well as independency of the solution from the problem. Abilities of proposed methods are examined with reference to an example system. To demonstrate these abilities, results are compared with binary genetic algorithm method. The proposed approaches can be perfectly applied to air-conditioning systems. (author)

  14. Testing of Model Water Chiller System with Hidrokarbon as a Primer Refrigeran

    Directory of Open Access Journals (Sweden)

    Nengah Suarnadwipa

    2012-11-01

    Full Text Available Now days, there are two issues that give a negative impact on the environment due to the uses of synthetic refrigerant on therefrigeration system and air conditioning system. The first issue was the Ozon Layer Depletion and the second issue was theGlobal Warming. Regarding those condition, it will be investigated the design and examination of performance the use of thesplit type AC system as water chiller system and using hydrocarbon as a primer refrigerant. As a result, in the examination ofthe standard split type AC system using refrigerant R-22, it founded that the cooling rate of 1958 Watt and COP of 5.29.While the examination on the modified split type AC system into water chiller system using hydrocarbon (hycool 22, hasgiven cooling rate of 1832 Watt and COP of 4.19. Finally, it could be councluded that the split type AC system could be usedas water chiller system.

  15. Experimental studies on a vapour compression system using ...

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology ... The addition of nanoparticles to the refrigerant results in improvements in the ... reduces by 25% when POE oil is replaced by a mixture of mineral oil and alumina nanoparticles.

  16. A novel energy-saving method for air-cooled chiller plant by parallel connection

    International Nuclear Information System (INIS)

    Zhang Xiaosong; Xu Guoying; Chan, K.T.; Yi Xia

    2006-01-01

    A novel method was put forward for improving the energy efficiency of air-cooled water chiller plant operating on part load conditions. The conventional multiple-chiller plant was proposed to be integrated into one refrigeration cycle, by connecting those separate compressors, condensers and evaporators in parallel, respectively. The integrated multiple-chiller plant uses the electronic expansion valve to control refrigerant flow, achieving variable condensing temperature control. A prototype composed of four reciprocating compressors (including one variable-speed compressor), with total nominal cooling capacity of 120 kW was simulated and experimented. Both the simulative and experimental results indicated that applying this novel energy-saving method, the air-cooled chiller plant could get a significant performance improvement on various part load ratio (PLR) conditions, due to the apparent decrease of condensing temperature and some increase of evaporating temperature. Under the same outdoor temperature of 35 o C, when the PLR decreased from 100% to 50%, the COP increased by about 16.2% in simulation and 9.5% in experiment. Also, the practical refrigeration output ratio of the system was 55% on the condition of 50% PLR

  17. Air-cooled LiBr-water absorption chillers for solar air conditioning in extremely hot weathers

    International Nuclear Information System (INIS)

    Kim, D.S.; Infante Ferreira, C.A.

    2009-01-01

    A low temperature-driven absorption cycle is theoretically investigated for the development of an air-cooled LiBr-water absorption chiller to be combined with low-cost flat solar collectors for solar air conditioning in hot and dry regions. The cycle works with dilute LiBr-water solutions so that risk of LiBr crystallization is less than for commercially available water-cooled LiBr-water absorption chillers even in extremely hot ambient conditions. Two-phase heat exchangers in the system were modelled taking account of the heat and mass transfer resistances in falling film flows by applying the film theory in thermal and concentration boundary layers. Both directly and indirectly air-cooled chillers were modelled by properly combining component models and boundary conditions in a matrix system and solved with an algebraic equation solver. Simulation results predict that the chillers would deliver chilled water around 7.0 deg. C with a COP of 0.37 from 90 deg. C hot water under 35 deg. C ambient condition. At 50 deg. C ambient temperature, the chillers retained about 36% of their cooling power at 35 deg. C ambient. Compared with the directly air-cooled chiller, the indirectly air-cooled chiller presented a cooling power performance reduction of about 30%

  18. Thermodynamic-behaviour model for air-cooled screw chillers with a variable set-point condensing temperature

    International Nuclear Information System (INIS)

    Chan, K.T.; Yu, F.W.

    2006-01-01

    This paper presents a thermodynamic model to evaluate the coefficient of performance (COP) of an air-cooled screw chiller under various operating conditions. The model accounts for the real process phenomena, including the capacity control of screw compressors and variations in the heat-transfer coefficients of an evaporator and a condenser at part load. It also contains an algorithm to determine how the condenser fans are staged in response to a set-point condensing temperature. The model parameters are identified, based on the performance data of chiller specifications. The chiller model is validated using a wide range of operating data of an air-cooled screw chiller. The difference between the measured and modelled COPs is within ±10% for 86% of the data points. The chiller's COP can increase by up to 115% when the set-point condensing temperature is adjusted, based on any given outdoor temperature. Having identified the variation in the chiller's COP, a suitable strategy is proposed for air-cooled screw chillers to operate at maximum efficiency as much as possible when they have to satisfy a building's cooling-load

  19. Real-time performance assessment and adaptive control for a water chiller unit in an HVAC system

    Science.gov (United States)

    Bai, Jianbo; Li, Yang; Chen, Jianhao

    2018-02-01

    The paper proposes an adaptive control method for a water chiller unit in a HVAC system. Based on the minimum variance evaluation, the adaptive control method was used to realize better control of the water chiller unit. To verify the performance of the adaptive control method, the proposed method was compared with an a conventional PID controller, the simulation results showed that adaptive control method had superior control performance to that of the conventional PID controller.

  20. Vapour pressures and enthalpies of vapourization of a series of the linear aliphatic nitriles

    International Nuclear Information System (INIS)

    Emel'yanenko, Vladimir N.; Verevkin, Sergey P.; Koutek, Bohumir; Doubsky, Jan

    2005-01-01

    Vapour pressures and the molar enthalpies of vapourization ΔlgHm-bar of the linear aliphatic nitriles C 7 -C 17 have been determined by the transpiration method. Kovat's indices of these compounds were measured by capillary gas-chromatography. A linear correlation of enthalpies of vapourization ΔlgHm-bar at T=298.15 K of the nitriles studied with the Kovats indices has been found

  1. Vapour trap development and operational experience

    International Nuclear Information System (INIS)

    Jansing, W.; Kirchner, G.; Menck, J.

    1977-01-01

    Sodium aerosols have the unpleasant characteristic that they deposit at places with low temperature level. This effect can be utilized when sodium aerosols are to be trapped at places which are determined beforehand. Thus vapour traps were developed which can filter sodium vapour from the cover gas. By this means the necessity was eliminated to heat all gas lines and gas systems with trace heaters just as all sodium lines are heated. It was of special interest for the INTERATOM to develop vapour traps which must not be changed or cleaned after a certain limited operating period. The vapour traps were supposed to enable maintenance free operation, i.e. they were to operate 'self cleaning'

  2. Autonomous Chemical Vapour Detection by Micro UAV

    Directory of Open Access Journals (Sweden)

    Kent Rosser

    2015-12-01

    Full Text Available The ability to remotely detect and map chemical vapour clouds in open air environments is a topic of significant interest to both defence and civilian communities. In this study, we integrate a prototype miniature colorimetric chemical sensor developed for methyl salicylate (MeS, as a model chemical vapour, into a micro unmanned aerial vehicle (UAV, and perform flights through a raised MeS vapour cloud. Our results show that that the system is capable of detecting MeS vapours at low ppm concentration in real-time flight and rapidly sending this information to users by on-board telemetry. Further, the results also indicate that the sensor is capable of distinguishing “clean” air from “dirty”, multiple times per flight, allowing us to look towards autonomous cloud mapping and source localization applications. Further development will focus on a broader range of integrated sensors, increased autonomy of detection and improved engineering of the system.

  3. Experimental study of a thermoelectrically-driven liquid chiller in terms of COP and cooling down period

    International Nuclear Information System (INIS)

    Faraji, Amir Yadollah; Goldsmid, H.J.; Akbarzadeh, Aliakbar

    2014-01-01

    Highlights: • A COP of 0.8 is achievable for a thermoelectrically-driven water chiller. • With two market available TEC modules with ZT around 0.7 sub-zero temperatures became applicable. • Forced air convection heat exchangers have better COP and CDP compared with natural convection. • A PID controller has several advantages against on–off controller for controlling TEC module. - Abstract: To study COP and other cooling parameters of a thermoelectically-driven liquid chiller, a 430 ml capacity liquid chiller incorporating two commercially available thermoelectric modules as its active components, has been designed, built and assessed. The system can use natural or forced air convection in heat exchangers attached to the thermoelectric module surfaces. The coefficient of performance (COP) and cooling down period (CDP) of the system for different thermoelectric input voltages have been measured. The COP of the thermoelectric chiller was found to be in the range 0.2–1.4 for forced convection and 0.2–1 for natural convection at a cooled liquid temperature of 10 °C and an ambient temperature of 18 °C. For the chiller, heat pumping capacity, minimum achievable water temperature, and temperature difference across the thermoelectric surfaces were investigated for input voltages of 3 V, 5 V, 7 V, 10 V and 12 V. Furthermore, as a basis for reliable and convenient control of the chiller, a proportional integral derivative (PID) controller has been proposed

  4. Experimental investigation of a small-scale thermally driven pressurized adsorption chiller

    KAUST Repository

    Loh, Waisoong; Ismail, Azhar Bin; Ng, Kim Choon; Chun, Wongee

    2015-01-01

    This paper describes the successful operation of an adsorption cycle in a miniaturized adsorption chiller (AD). The experiments show that the bench-scale pressurized adsorption chiller (PAC) has been successfully designed, commissioned, and tested. Experimental results at various heat fl uxes, half-cycle operation time intervals, and a cooling load of up to 24 W are also presented. A COP ranging from 0.05 to 0.15 is achieved depending on the parameters of the experimental conditions. Most importantly, the cooling performance of the PAC is achieved at a low encasement temperature that is below ambient. Besides having a high cooling density, the PAC has almost no major moving parts except for the fan of the condenser and it permits quiet operation as compared to other active coolers.

  5. Simulation of adsorber tube diameter's effect on new design silica gel-water adsorption chiller

    Science.gov (United States)

    Nasruddin, Taufan, A.; Manga, A.; Budiman, D.

    2017-03-01

    A new design of silica gel-water adsorption chiller is proposed. The design configuration is composed of two sorption chambers with compact fin tube heat exchangers as adsorber, condenser, and evaporator. Heat and mass recovery were adopted in order to increase the cooling capacity. Numerical modelling and calculation were used to show the performance of the chiller with different adsorber tube diameter. Under typical condition for hot water inlet/cooling water inlet/chilled water outlet temperatures are 90/30/7°C, respectively, the simulation results showed the best average value of COP, SCP, and cooling power are 0.19, 15.88 W/kg and 279.89 W using 3/8 inch tube.

  6. Capillary Tube and Thermostatic Expansion Valve Comparative Analysis in Water Chiller Air Conditioning

    Science.gov (United States)

    Wijaya Sunu, Putu; Made Rasta, I.; Anakottapary, Daud Simon; Made Suarta, I.; Cipta Santosa, I. D. M.

    2018-01-01

    The aims of this study to compares the performance characteristics of a water chiller air conditioning simulation equipped with thermostatic expansion valve (TEV) with those of a capillary tube. Water chiller system filled with the same charge of refrigerant. Comparative analyses were performed based on coefficient of performance (COP) and performance parameter of the refrigeration system, carried out at medium cooling load level with the ambient temperature of 29-31°C, constant compressor speed and fixed chilled water volume flowrate at 15 lpm. It was shown that the TEV system showed better energy consumption compared to that of capillary tube. From the coefficient of performance perspective, the thermostatic expansion valve system showed higher COP (± 21.4%) compared to that of capillary tube system.

  7. Performance of a LiBr water absorption chiller operating with plate heat exchangers

    OpenAIRE

    Vega Blázquez, Mercedes de; Almendros Ibáñez, José Antonio; Ruiz, G.

    2006-01-01

    This paper studies the performance of a lithium bromide water absorption chiller operating with plate heat exchangers (PHE). The overall heat transfer coefficients in the desorber, the condenser and the solution heat recoverer are calculated using the correlations provided in the literature for evaporation, condensation and liquid to liquid heat transfer in PHEs. The variable parameters are the external driving temperatures. In the desorber, the inlet temperature of the hot fluid ranges from ...

  8. Design and performance prediction of a new generation adsorption chiller using composite adsorbent

    International Nuclear Information System (INIS)

    Gong, L.X.; Wang, R.Z.; Xia, Z.Z.; Chen, C.J.

    2011-01-01

    Research highlights: → Composite adsorbent 'employing lithium chloride in silica gel' and water as working pair. → A new type adsorbent bed is used to accommodate the composite adsorbent. → A dynamic model of the adsorption chiller is built. → The coefficient of performance (COP) and the cooling capacity will be improved. -- Abstract: This paper presents a novel adsorption chiller using composite adsorbent 'employing lithium chloride in silica gel' as adsorbent and water as adsorbate. A new type adsorbent bed is used to accommodate the composite adsorbent. The mass recovery between two adsorbent beds usually results in the adsorbate unbalance. So a novel auto water makeup unite is used to solve the problem. A dynamic model of the adsorption chiller is built based on the adsorption isotherms to predict the performance. The simulation result shows that the coefficient of performance (COP) and the cooling capacity will increase by using this new composite adsorbent. When the temperatures of hot water inlet, cooling water inlet, and chilled water inlet are 363, 303 and 293 K, COP will be 0.43, and the cooling capacity will be 5.295 kW. Also operation strategy is optimized. Different temperatures of hot water inlet, cooling water inlet and chilling water inlet will result in different COP and cooling capacity.

  9. Feasibility study on the application of a heat-pipe type adsorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sang Hyeok; Chung, Jae Dong [Dept. of Mechanical Engineering, Sejong University, Seoul (Korea, Republic of); Kwon, Oh Kyung [Energy System R and D Group, Korea Institute of Industrial Technology, Cheonan (Korea, Republic of)

    2017-01-15

    A parametric study on a heat-pipe type adsorption chiller with SWS-1L (mesoporous silica gel impregnated with CaCl{sub 2}) and water pair was conducted using a numerical method in this research. A heat pipe that is in direct contact with the adsorbent is applied to the adsorption chiller to improve the heat transfer capacity of the adsorption bed. A feasibility study was performed on the heat-pipe type adsorption bed with a single layer. The Coefficient of performance (COP) and the Specific cooling power (SCP) were 0.231 and 844.8 W/kg, respectively. These values are lower than the system performance values of the existing fin-tube type adsorption bed. However, when the number of bed layers was increased to seven, the COP and SCP of the heat-pipe type adsorption bed were 0.520 and 752.4 W/kg, respectively. These values are 5.25 % and 39.8 % higher than the COP and SCP, respectively, of the fin-tube type adsorption bed. These findings indicate that the heat-pipe type adsorption bed can potentially address the disadvantage caused by the system size of the adsorption chiller. A parametric study was also conducted for six design parameters, namely, number of layers, heat pipe pitch, heat pipe radius, fin width, fin spacing, and hot water temperature.

  10. Performance of a LiBr-water absorption chiller operating with plate heat exchangers

    International Nuclear Information System (INIS)

    Vega, M. de; Almendros-Ibanez, J.A.; Ruiz, G.

    2006-01-01

    This paper studies the performance of a lithium bromide-water absorption chiller operating with plate heat exchangers (PHE). The overall heat transfer coefficients in the desorber, the condenser and the solution heat recoverer are calculated using the correlations provided in the literature for evaporation, condensation and liquid to liquid heat transfer in PHEs. The variable parameters are the external driving temperatures. In the desorber, the inlet temperature of the hot fluid ranges from 75 deg. C to 105 deg. C. In the condenser and the absorber, the inlet temperature of the cooling water goes from 20 deg. C to 40 deg. C. The coefficient of performance (COP) obtained ranges from 0.5 to 0.8 for cooling duties ranging from 2 kW to 12 kW. The chiller response to different hot fluid temperatures and circulated mass flow rates is also presented. The performance and the internal parameters of the chiller at part load are, therefore, calculated. A higher efficiency results when the solution pumped from the absorber to the desorber decreases. The heat transfer analysis of the PHEs is also presented. The overall heat transfer coefficient in the desorber, equal to 790 W/m 2 K at the design conditions, is also analysed at part load. The condenser performance can be represented by a similar relationship found in conventional air cooled condensers

  11. Feasibility study on the application of a heat-pipe type adsorption chiller

    International Nuclear Information System (INIS)

    Ahn, Sang Hyeok; Chung, Jae Dong; Kwon, Oh Kyung

    2017-01-01

    A parametric study on a heat-pipe type adsorption chiller with SWS-1L (mesoporous silica gel impregnated with CaCl_2) and water pair was conducted using a numerical method in this research. A heat pipe that is in direct contact with the adsorbent is applied to the adsorption chiller to improve the heat transfer capacity of the adsorption bed. A feasibility study was performed on the heat-pipe type adsorption bed with a single layer. The Coefficient of performance (COP) and the Specific cooling power (SCP) were 0.231 and 844.8 W/kg, respectively. These values are lower than the system performance values of the existing fin-tube type adsorption bed. However, when the number of bed layers was increased to seven, the COP and SCP of the heat-pipe type adsorption bed were 0.520 and 752.4 W/kg, respectively. These values are 5.25 % and 39.8 % higher than the COP and SCP, respectively, of the fin-tube type adsorption bed. These findings indicate that the heat-pipe type adsorption bed can potentially address the disadvantage caused by the system size of the adsorption chiller. A parametric study was also conducted for six design parameters, namely, number of layers, heat pipe pitch, heat pipe radius, fin width, fin spacing, and hot water temperature

  12. Design and experimental analysis of a carbon dioxide transcritical chiller for commercial refrigeration

    International Nuclear Information System (INIS)

    Cecchinato, Luca; Chiarello, Manuel; Corradi, Marco

    2010-01-01

    Carbon dioxide is an interesting solution for commercial refrigeration and in perspective for air-conditioning systems. In this paper a newly developed carbon dioxide transcritical air cooled chiller for refrigerating propylene glycol down to -8 o C supply temperature is described. The aim of the project was at optimising the cycle energy efficiency while assuring reliable operation and simple management of the unit. The carbon dioxide optimal pressure issue is addressed with an innovate system architecture and control logic. Using a flash tanks and two electronic valves, the optimal cycle upper pressure was maintained in transcritical operation mode. The managing of the valves allows the refrigeration machine efficiency improvement when the gas cooler inlet air allows subcritical working conditions. A simulation model of the chiller was developed and its results validated with experimental data. A measurement campaign was carried out, testing the chiller at external temperatures ranging from 18 to 35 o C, the unit energy efficiency ranging from 3.1 to 2.0.

  13. Modelling and adaptive control of small capacity chillers for HVAC applications

    International Nuclear Information System (INIS)

    Beghi, A.; Cecchinato, Luca

    2011-01-01

    An adaptive controller for single and uneven tandem scroll compressor, packaged air-cooled water chillers is described. The designed controller allows to substantially increase the energy performance of the system, as well as to achieve excellent regulation performances in process applications. The controller parameters are adapted on the basis of estimates of the plant thermal load, that are computed by using a Kalman filter. An ad hoc approach is used to define a relay control logic, which is based on a numerical optimization procedure. To support controller design, a detailed simulation environment is developed and validated on an experimental facility. Performance of the algorithm is described with both simulation and experimental data. At low part load ratio values the proposed algorithm grants a 0.6-0.7 K improvement in the regulation performance in terms of supply water temperature standard deviation and mean supply water temperature deviation. The unit energy efficiency improvement with respect to supply water temperature control varies from 7.3% to 3.0% while the experimental seasonal energy efficiency rating improvement is 9.1%. - Research highlights: → Design of an advanced control algorithms for small capacity chillers. → Matlab/Simulink simulation environment development and experimental validation. → Development of an adaptive control algorithm for scroll compressor chillers, which allows to increase both control accuracy and energy performance. → New load estimation scheme based on a Kalman filter.

  14. An externally heated copper vapour laser

    International Nuclear Information System (INIS)

    Rochefort, P.A.; Sopchyshyn, F.C.; Selkirk, E.B.; Green, L.W.

    1993-08-01

    A pulsed Copper Vapour Laser (CVL), with a nominal 6 kHz repetition rate, was designed, build, and commissioned at Chalk River laboratories. The laser was required for Resonant Ionization Mass Spectroscopy (RIMS) experiments and for projects associated with Atomic Vapour laser Isotope Separation (AVLIS) studies. For the laser to operate, copper coupons position along the length of a ceramic tube must be heated sufficiently to create an appropriate vapour pressure. The AECL CVL uses an external heater element with a unique design to raise the temperature of the tube. The Cylindrical graphite heating element is shaped to compensate for the large radiation end losses of the laser tube. The use of an external heater saves the expensive high-current-voltage switching device from heating the laser tube, as in most commercial lasers. This feature is especially important given the intermittent usage typical of experimental research. As well, the heater enables better parametric control of the laser output when studying the lasing of copper (or other) vapour. This report outlines the lasing process in copper vapour, describes in detail all three major laser sub-systems: the laser body; the laser tube heater; the high voltage pulsed discharge; and, reports parametric measurements of the individual sub-systems and the laser system as a whole. Also included are normal operating procedures to heat up, run and shut down the laser

  15. DNABIT Compress - Genome compression algorithm.

    Science.gov (United States)

    Rajarajeswari, Pothuraju; Apparao, Allam

    2011-01-22

    Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, "DNABIT Compress" for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our proposed algorithm achieves the best compression ratio for DNA sequences for larger genome. Significantly better compression results show that "DNABIT Compress" algorithm is the best among the remaining compression algorithms. While achieving the best compression ratios for DNA sequences (Genomes),our new DNABIT Compress algorithm significantly improves the running time of all previous DNA compression programs. Assigning binary bits (Unique BIT CODE) for (Exact Repeats, Reverse Repeats) fragments of DNA sequence is also a unique concept introduced in this algorithm for the first time in DNA compression. This proposed new algorithm could achieve the best compression ratio as much as 1.58 bits/bases where the existing best methods could not achieve a ratio less than 1.72 bits/bases.

  16. Compression stockings

    Science.gov (United States)

    Call your health insurance or prescription plan: Find out if they pay for compression stockings. Ask if your durable medical equipment benefit pays for compression stockings. Get a prescription from your doctor. Find a medical equipment store where they can ...

  17. Measured performance of a 3 ton LiBr absorption water chiller and its effect on cooling system operation

    Science.gov (United States)

    Namkoong, D.

    1976-01-01

    A three ton lithium bromide absorption water chiller was tested for a number of conditions involving hot water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It was concluded that a three-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

  18. Measured performance of a 3-ton LiBr absorption water chiller and its effect on cooling system operation

    Science.gov (United States)

    Namkoong, D.

    1976-01-01

    A 3-ton lithium bromide absorption water chiller was tested for a number of conditions involving hot-water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It is concluded that a 3-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

  19. Water vapour loss measurements on human skin.

    NARCIS (Netherlands)

    Valk, Petrus Gerardus Maria van der

    1984-01-01

    In this thesis, the results of a series of investigations into the barrier function of human skin are presented. In these investigations, the barrier function was assessed by water vapour loss measurements of the skin using a method based on gradient estimation.... Zie: Summary and conclusions

  20. A mathematical model of vapour film destabilisation

    International Nuclear Information System (INIS)

    Knowles, J.B.

    1985-04-01

    In a hypothetical reactor accident, destabilisation of an intervening vapour film between the molten fuel and liquid coolant by a weak shock wave (trigger), is considered likely to initiate the molten fuel-coolant interaction. The one-dimensional model presented here is part of a larger programme of fundamental research aimed at improved reactor safety. (U.K.)

  1. Evaluation of trigeneration system using microturbine, ammonia-water absorption chiller, and a heat recovery boiler

    Energy Technology Data Exchange (ETDEWEB)

    Preter, Felipe C.; Rocha, Marcelo S.; Simoes-Moreira, Jose Roberto [SISEA - Alternative Energy Systems Lab. Dept. of Mechanical Engineering. University of Sao Paulo (EP/USP), SP (Brazil)], e-mails: felipe.preter@poli.usp.br, msrocha@poli.usp.br, jrsimoes@usp.br; Andreos, Ronaldo [COMGAS - Companhia de Gas de Sao Paulo, SP (Brazil)], e-mail: randreos@comgas.com.br

    2010-07-01

    In this work, a CCHP or tri generation system has been projected, mounted, and tested in laboratory, combining a microturbine for power generation, a heat recovery boiler for hot water production, and an ammonia water absorption chiller for chilled water production. The project was motivated by the large practical applications of this kind of energy recovery system in commerce, and industry, and, in general, more than 85% of the energy source is used as power, hot water, and cold water. In the first part, the trigeneration system theoretical model is detailed, and in the second part, experimental results are presented for different operation conditions. (author)

  2. Trigeneration System Based on Municipal Waste Gasification, Fuel Cell and an Absorption Chiller

    DEFF Research Database (Denmark)

    Katsaros, Giannis; Nguyen, Tuong-Van; Rokni, Masoud

    2016-01-01

    of a specific building is also investigated and the system can fully meet the electricity and cooling demands, whereas the heat needs can be satisfied only up to 55%. Moreover, assuming 20 years of operation, the payback period is 4.3 years and the net present value exceeds 5 MEUR.......The present work focuses on the design of a novel tri-generation system based on municipal solid wastes gasification, solid oxide fuel cell and an ammonia-water absorption chiller. Trigeneration systems can be implemented in buildings such as hospitals, where there is a continuous and large demand...

  3. Engineering Task Plan for Tank 241-C-106 contingency chiller definitive design

    International Nuclear Information System (INIS)

    Rensink, G.E.; Kriskovich, J.R.

    1995-01-01

    This document identifies the scope, cost, schedule and responsible organizations for completing a design of a contingency ventilation inlet air cooling system for Tank 241-C-106. The air cooling system, described in Rensink (1995), consists of a chiller, cooling coils, and supporting equipment that, when installed will be capable of assuring that the waste temperatures in Tank 241-C-106 are maintained within acceptable limits for safe storage. The effort described herein is scheduled for completion by May 31, 1995 to support Performance Based Incentive (PBI) Milestone SI-2x

  4. Modelling and testing the performance of a commercial ammonia/water absorption chiller using Aspen-Plus platform

    International Nuclear Information System (INIS)

    Mansouri, Rami; Boukholda, Ismail; Bourouis, Mahmoud; Bellagi, Ahmed

    2015-01-01

    A steady-state simulation model of a commercial 3-ton ammonia/water absorption chiller is developed and validated using the flow-sheeting software Aspen-Plus. First an appropriate thermodynamic property model for the ammonia/water fluid mixture is selected. To this purpose nine methods from the software library are pre-selected and tested, but none of the methods predicts the VLE (vapour–liquid equilibrium) with sufficient accuracy. The interaction parameters of these models are then determined by fitting the equations of state (EOS) to VLE data. It is finally found that the Boston–Mathias modified Peng–Robinson EOS with fitted parameters predicts most accurately the VLE for the temperature and pressure ranges encountered in commercial chillers. A simulation model of the machine is then developed. The simulation results are found to be in good agreement with data from literature at a cooling air temperature of 35 ºC. The heat transfer characteristics (UA) of the various heat exchangers of the machine are then determined and the model modified to make it accept these (UA) as input parameters. The comparison of the simulation predictions at cooling air temperatures of 26.7 and 38 ºC with the bibliographical data showed good concordance. The proposed model could be very useful for the analysis and performance prediction of the commercial absorption chiller. - Highlights: • A commercial NH 3 /H 2 O absorption chiller is simulated using the software Aspen-Plus. • Peng-Robinson-Boston-Mathias equation of state is used to predict VLE of NH 3 /H 2 O fluid mixture. • A steady-state model describing the chiller operation is developed. • The model predicts the internal operating conditions and COP of the chiller.

  5. Screw compressors for applications in liquid chillers and heat pumps; Schraubenverdichter fuer Anwendungen in Fluessigkeitskuehlsaetzen und Waermepumpen

    Energy Technology Data Exchange (ETDEWEB)

    Grosse-Kracht, Rainer [Bitzer Kuehlmaschinenbau GmbH, Sindelfingen (Germany)

    2009-05-15

    The demands on compressors for liquid chillers and heat pumps are changing continuously, with energy efficiency becoming ever more of a key focus. Especially certification programs are rating part load conditions higher than full load conditions. Another aspect is the lowering of the condensing temperature in order to achieve an increase in efficiency. Bitzer offers three compressor series optimized for these requirements: The CSH series for air-cooled liquid chillers and heat pumps; the CSW series, developed on the basis of the CSH, for low condensing temperatures occurring in water-cooled systems; and the HS.VS with frequency inverter for high part load efficiencies. (orig.)

  6. Part load efficiency of packaged air-cooled water chillers with inverter driven scroll compressors

    International Nuclear Information System (INIS)

    Cecchinato, Luca

    2010-01-01

    In this paper different packaged air-cooled systems, operating on scroll compressors, are experimentally analysed from the point of view of the relation between energy efficiency and actual capacity. Single compressor, double compressors and double compressors with uneven volumetric capacity units are tested. Experimental tests demonstrated that cooling capacity control by means of variation of rotational speed is an suitable solution for improving the part load efficiency of these systems. Step capacity units obtained by splitting the system volumetric capacity between two compressors are also effective solutions. Nevertheless they appear to be more efficient than single inverter driven chillers only for part load conditions lower than 60%. In the analysed cooling capacity range (25-50 kW), tandem compressors chillers with one inverter driven compressor appear the most efficient solution combining rotational speed with step capacity control. Seasonal energy efficiency ratios were obtained with prEN 14825 calculation method confirming reduced energy consumption associated to continuous and step cooling capacity control.

  7. Energetic, exergetic and financial evaluation of a solar driven absorption chiller – A dynamic approach

    International Nuclear Information System (INIS)

    Bellos, Evangelos; Tzivanidis, Christos; Symeou, Christoforos; Antonopoulos, Kimon A.

    2017-01-01

    Highlights: • A solar cooling system with ETC and a single effect absorption chiller is analyzed. • The analysis is dynamic and it is made for the city of Athens, Greece. • The analysis is energetic, exergetic and financial for all the summer period. • Firstly the system is optimized exergetically and after it is analyzed financially. • The optimum case is 450 m"2 of solar collectors coupled with a storage tank of 14 m"3. - Abstract: In this study, a solar cooling system of 100 kW is analyzed parametrically in dynamic basis for the city of Athens, Greece. The objective of this study is the design of a sustainable system, using energetic, exergetic and financial criteria. The examined system includes evacuated tube collectors, storage tank and a single stage absorption chiller operating with LiBr-H_2O working pair. Different combinations of collecting areas and storage tank volumes are tested in order to determine the most suitable cases exergetically. These optimum cases are evaluated financially and finally the system with the higher financial indexes is selected as the most suitable. More specifically, the collecting area is analyzed from 150 m"2 to 600 m"2 and the storage tank from 6 m"3 to 16 m"3. Finally, 450 m"2 of evacuated tube collectors with a 14 m"3 storage tank was proved to be the optimum solution financially with 15 years payback period and 67 k€ net present value.

  8. Dynamic Performance Analysis for an Absorption Chiller under Different Working Conditions

    Directory of Open Access Journals (Sweden)

    Jian Wang

    2017-08-01

    Full Text Available Due to the merits of energy saving and environmental protection, the absorption chiller (AC has attracted a lot of attention, and previous studies only concentrated on the dynamic response of the AC under a single working condition. However, the working conditions are usually variable, and the dynamic performance under different working conditions is beneficial for the adjustment of AC and the control of the whole system, of which the stabilization can be affected by the AC transient process. Therefore, the steady and dynamic models of a single-effect H2O-LiBr absorption chiller are built up, the thermal inertia and fluid storage are also taken into consideration. And the dynamic performance analyses of the AC are completed under different external parameters. Furthermore, a whole system using AC in a process plant is analyzed. As a conclusion, the time required to reach a new steady-state (relaxation time increases when the step change of the generator inlet temperature becomes large, the cooling water inlet temperature rises, or the evaporator inlet temperature decreases. In addition, the control strategy considering the AC dynamic performance is favorable to the operation of the whole system.

  9. Development of design program for small-sized gas absorption chiller/heaters

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, J.I.; Kwon, O.K.; Moon, C.K. [Pukyong National University, Pusan (Korea); Yang, Y.M.; Kim, H.Y. [R and D Center, Korea Gas Corporation, Ansan (Korea)

    1999-10-01

    Analysis of basic data is performed for development of small size water-cooled household absorption chiller/heater using non CFC refrigerant, analytic simulation program of air cooling performance is developed that system has 1.5-10RT of air cooling performance, we perform cycle analysis and numerical simulation. We develope a performance analysis of simulation program to perform a basic design for 1.5-10RT apparatus of small size system of development model in gas driven double effect absorption chiller/heater. The system working condition and operation limit condition is decided from the existing data which is analyzed and the conference with KOGAS. After the basic input variable and regular condition is established for heat cycle analysis, the simulation algorithm is set up and performance simulation program is coded according to the organized algorithm. The basic design of optimum system is completed from parametric study using developed simulation program and establishing the design variable range of developing object model. 20 refs., 30 figs., 9 tabs.

  10. Experimental investigation on the optimal performance of Zeolite-water adsorption chiller

    KAUST Repository

    Myat, Aung

    2013-02-01

    This paper presents the performance testing of Zeolite adsorption cooling system driven by low grade waste heat source extracted from prime mover\\'s exhaust, power plant\\'s exhaust and the solar energy. The adsorbent FAM Z01 is used as an adsorbent in the adsorption chiller facility. Owing to its large equilibrium pore volume, it has the high affinity for the water vapor adsorbate. The key advantages of the Zeolite adsorption cooling system are: (i) it has no moving parts rendering less maintenance, (ii) the energy efficient means of cooling by the adsorption process with a low temperature heat source, (iii) the use of vapor pipes are replaced by self actuating vapor valves rendering smaller footprint area and (iv) it is environmental friendly with low carbon footprint. The experimental investigations were carried out for Zeolite adsorption chiller at different key operating conditions namely (i) heat source temperature, (ii) the cycle time and (iii) the heat recovery time. It is investigated that performance of coefficient (COP) of this system could be as high as 0.48 while the waste heat source temperature is applicable as low as 55 °C. © 2012.

  11. Vapour pressure of caesium over nuclear graphite

    International Nuclear Information System (INIS)

    Faircloth, R.L.; Pummery, F.C.W.

    1976-01-01

    The vapour pressure of caesium over a fine-grained isotropic moulded gilsocarbon nuclear graphite intended for use in the manufacture of fuel tubes for the high temperature reactor has been determined as a function of temperature and concentration by means of the Knudsen effusion technique. The concentration range 0 to 10 μg caesium/g graphite was investigated and it was concluded that a Langmuir adsorption situation exists under these conditions. (author)

  12. Interactions of fission product vapours with aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Benson, C G; Newland, M S [AEA Technology, Winfrith (United Kingdom)

    1996-12-01

    Reactions between structural and reactor materials aerosols and fission product vapours released during a severe accident in a light water reactor (LWR) will influence the magnitude of the radiological source term ultimately released to the environment. The interaction of cadmium aerosol with iodine vapour at different temperatures has been examined in a programme of experiments designed to characterise the kinetics of the system. Laser induced fluorescence (LIF) is a technique that is particularly amenable to the study of systems involving elemental iodine because of the high intensity of the fluorescence lines. Therefore this technique was used in the experiments to measure the decrease in the concentration of iodine vapour as the reaction with cadmium proceeded. Experiments were conducted over the range of temperatures (20-350{sup o}C), using calibrated iodine vapour and cadmium aerosol generators that gave well-quantified sources. The LIF results provided information on the kinetics of the process, whilst examination of filter samples gave data on the composition and morphology of the aerosol particles that were formed. The results showed that the reaction of cadmium with iodine was relatively fast, giving reaction half-lives of approximately 0.3 s. This suggests that the assumption used by primary circuit codes such as VICTORIA that reaction rates are mass-transfer limited, is justified for the cadmium-iodine reaction. The reaction was first order with respect to both cadmium and iodine, and was assigned as pseudo second order overall. However, there appeared to be a dependence of aerosol surface area on the overall rate constant, making the precise order of the reaction difficult to assign. The relatively high volatility of the cadmium iodide formed in the reaction played an important role in determining the composition of the particles. (author) 23 figs., 7 tabs., 22 refs.

  13. Interactions of fission product vapours with aerosols

    International Nuclear Information System (INIS)

    Benson, C.G.; Newland, M.S.

    1996-01-01

    Reactions between structural and reactor materials aerosols and fission product vapours released during a severe accident in a light water reactor (LWR) will influence the magnitude of the radiological source term ultimately released to the environment. The interaction of cadmium aerosol with iodine vapour at different temperatures has been examined in a programme of experiments designed to characterise the kinetics of the system. Laser induced fluorescence (LIF) is a technique that is particularly amenable to the study of systems involving elemental iodine because of the high intensity of the fluorescence lines. Therefore this technique was used in the experiments to measure the decrease in the concentration of iodine vapour as the reaction with cadmium proceeded. Experiments were conducted over the range of temperatures (20-350 o C), using calibrated iodine vapour and cadmium aerosol generators that gave well-quantified sources. The LIF results provided information on the kinetics of the process, whilst examination of filter samples gave data on the composition and morphology of the aerosol particles that were formed. The results showed that the reaction of cadmium with iodine was relatively fast, giving reaction half-lives of approximately 0.3 s. This suggests that the assumption used by primary circuit codes such as VICTORIA that reaction rates are mass-transfer limited, is justified for the cadmium-iodine reaction. The reaction was first order with respect to both cadmium and iodine, and was assigned as pseudo second order overall. However, there appeared to be a dependence of aerosol surface area on the overall rate constant, making the precise order of the reaction difficult to assign. The relatively high volatility of the cadmium iodide formed in the reaction played an important role in determining the composition of the particles. (author) 23 figs., 7 tabs., 22 refs

  14. The impact of water vapour on climate

    International Nuclear Information System (INIS)

    Zittel, W.; Altmann, M.

    1994-01-01

    Do water vapour emissions from a solar hydrogen system affect the climate? This question was investigated by the authors. They state: The comparison with natural emissions by evaporation shows that emissions caused by energy generation, regardless of whether they stem from fossil, nuclear or regenerative energy systems, are negligible with a proportion of 0.005%. On the other hand, carbon dioxide emissions with a proportion of 4%, constitute a factor which already impedes the natural cycle. (orig.) [de

  15. Bibliography on vapour pressure isotope effects

    International Nuclear Information System (INIS)

    Illy, H.; Jancso, G.

    1976-03-01

    The bibliography of research on vapour pressure isotope effects from 1919 to December 1975 is presented in chronological order. Within each year the references are listed alphabetically according to the name of the first author of each work. The bibliography is followed by a Compound Index containing the names o compounds, but the type of isotopic substituation is not shown. The Author Index includes all authors of the papers. (Sz.N.Z.)

  16. Modeling and simulation of a 100 kWe HT-PEMFC subsystem integrated with an absorption chiller subsystem

    DEFF Research Database (Denmark)

    Arsalis, Alexandros

    2012-01-01

    A 100 kWe liquid-cooled HT-PEMFC subsystem is integrated with an absorption chiller subsystem to provide electricity and cooling. The system is designed, modeled and simulated to investigate the potential of this technology for future novel energy system applications. Liquid-cooling can provide...

  17. The Development and Full-Scale Experimental Validation of an Optimal Water Treatment Solution in Improving Chiller Performances

    Directory of Open Access Journals (Sweden)

    Chen-Yu Chiang

    2016-06-01

    Full Text Available An optimal solution, in combining physical and chemical water treatment methods, has been developed. This method uses a high voltage capacitance based (HVCB electrodes, coupled with biocides to form a sustainable solution in improving chiller plant performances. In this study, the industrial full-scale tests, instead of laboratory tests, have been conducted on chiller plants at the size of 5000 RT to 10,000 RT cooling capacities under commercial operation for more than two years. The experimental results indicated that the condenser approach temperatures can be maintained at below 1 °C for over two years. It has been validated that the coefficient of performance (COP of a chiller can be improved by over 5% by implementing this solution. Every 1 °C reduction in condenser approach temperature can yield approximately 3% increase on chiller COP, which warrants its future application potential in the HVAC industry, where Ta can degrade by 1 °C every three to six months. The solution developed in this study could also reduce chemical dosages and conserve makeup water substantially and is more environment friendly.

  18. Two 175 ton geothermal chiller heat pumps for leed platinum building technology demonstration project. Operation data, data collection and marketing

    Energy Technology Data Exchange (ETDEWEB)

    Kolo, Daniel [Johnson Controls, Inc., Glendale, WI (United States)

    2016-08-15

    The activities funded by this grant helped educate and inform approximately six thousand individuals who participated in guided tours of the geothermal chiller plant at Johnson Controls Corporate Headquarters in Glendale, Wisconsin over the three year term of the project. In addition to those who took the formal tour, thousands more were exposed to hands-on learning at the self-service video kiosks located in the headquarters building and augmented reality tablet app that allowed for self-guided tours. The tours, video, and app focused on the advantages of geothermal heat pump chillers, including energy savings and environmental impact. The overall tour and collateral also demonstrated the practical application of this technology and how it can be designed into a system that includes many other sustainable technologies without sacrificing comfort or health of building occupants Among tour participants were nearly 1,000 individuals, representing 130 organizations identified as potential purchasers of geothermal heat pump chillers. In addition to these commercial clients, tours were well attended by engineering, facilities, and business trade groups. This has also been a popular tour for groups from Universities around the Midwest and K-12 schools from Wisconsin and Northern Illinois A sequence of operations was put into place to control the chillers and they have been tuned and maintained to optimize the benefit from the geothermal water loop. Data on incoming and outgoing water temperature and flow from the geothermal field was logged and sent to DOE monthly during the grant period to demonstrate energy savings.

  19. Energy and Exergy Analysis for Improving the Energy Performance of Air-Cooled Liquid Chillers by Different Condensing-Coil Configurations

    Directory of Open Access Journals (Sweden)

    Tzong-Shing Lee

    2012-03-01

    Full Text Available This study constructed a parameter analysis for improving the energy performance of air-cooled water chillers by altering the angle configuration of the condenser coils. The mathematical models for energy and exergy analyses of the individual components and overall system of air-cooled water chillers are presented. This study investigated the potential enhancement of performance efficiency in air-cooled chillers and the energy conversion efficiency of each component, in order to determine how the angle configuration of condenser coils influences chiller performance. This study found that the overall performance of an air-cooled chiller could be improved by approximately 3.4%, and the total irreversibility could be reduced by approximately 2.7%. With each 1% increase in average wind speed over the condenser coils, the overall performance of an air‑cooled chiller was found to be enhanced by approximately 0.43%, and its total irreversibility was reduced by approximately 0.35%. The results of this study can be effectively applied to air-cooled condenser units, and can provide an important basis of reference for developing and enhancing the energy efficiency of air-cooled chillers.

  20. Performance optimization of solar driven small-cooled absorption–diffusion chiller working with light hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Sayadi, Zouhour [U.R. Thermique et Thermodynamique des Procédés Industriels, Ecole Nationale d’Ingénieurs de Monastir (ENIM), Av. Ibn Jazzar, 5060 Monastir (Tunisia); Ben Thameur, Nizar, E-mail: nizarbenthameur@yahoo.fr [U.R. Thermique et Thermodynamique des Procédés Industriels, Ecole Nationale d’Ingénieurs de Monastir (ENIM), Av. Ibn Jazzar, 5060 Monastir (Tunisia); Bourouis, Mahmoud [Mechanical Engineering Department, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Bellagi, Ahmed [U.R. Thermique et Thermodynamique des Procédés Industriels, Ecole Nationale d’Ingénieurs de Monastir (ENIM), Av. Ibn Jazzar, 5060 Monastir (Tunisia)

    2013-10-15

    Highlights: • 1 kW{sub cooling} diffusion/absorption machine with light hydrocarbons as working fluids. • Hysys optimization to choose the optimal mixture for a better machine performance. • Cooling loads for a small bed-room (16 m{sup 2}) have been estimated into TRNSYS. • Economic assessment to choose the best combination of solar equipments. • Energy savings, CO{sub 2} avoided and equivalent gasoil and Diesel saved energy. - Abstract: We present in this paper a HYSYS (Aspen One) model and simulation results for 1 kW capacity water-cooled absorption/diffusion machine using different binary mixtures of light hydrocarbons as working fluids (C{sub 3}/n-C{sub 6}, C{sub 3}/c-C{sub 6}, C{sub 3}/c-C{sub 5}, propylene/c-C{sub 5}, propylene/i-C{sub 4}, propylene/i-C{sub 5}) in combination with helium as inert gas. The driving heat is supposed to be provided by an evacuated solar collector field. TRNSYS is used to address the solar aspects of the simulations. For the optimal chiller the driving heat temperature was found to be 121 °C for an evaporator exit temperature of 0 °C. The cooling water flow rate circulating between chiller and cooling tower is 140 l/h. Bubble pump and generator are heated by pressurized water from an insulated tank (70 l/m{sup 2}) maintained at a maximum temperature of 126 °C – with make-up heat when needed – and storing solar heat at an estimated 4.2 kW power. The solar energy cover only 40% for the energy supplied to drive the chiller. It’s found that the necessary collector surface area is about 6 m{sup 2} with annually total costs of 1.60 €/kW h with 20 years lifetime period for the installation. The avoided CO{sub 2} emissions are estimated at 1396 kg. The equivalent saved energy is 521 l of diesel or 604 l of gasoline.

  1. Performance optimization of solar driven small-cooled absorption–diffusion chiller working with light hydrocarbons

    International Nuclear Information System (INIS)

    Sayadi, Zouhour; Ben Thameur, Nizar; Bourouis, Mahmoud; Bellagi, Ahmed

    2013-01-01

    Highlights: • 1 kW cooling diffusion/absorption machine with light hydrocarbons as working fluids. • Hysys optimization to choose the optimal mixture for a better machine performance. • Cooling loads for a small bed-room (16 m 2 ) have been estimated into TRNSYS. • Economic assessment to choose the best combination of solar equipments. • Energy savings, CO 2 avoided and equivalent gasoil and Diesel saved energy. - Abstract: We present in this paper a HYSYS (Aspen One) model and simulation results for 1 kW capacity water-cooled absorption/diffusion machine using different binary mixtures of light hydrocarbons as working fluids (C 3 /n-C 6 , C 3 /c-C 6 , C 3 /c-C 5 , propylene/c-C 5 , propylene/i-C 4 , propylene/i-C 5 ) in combination with helium as inert gas. The driving heat is supposed to be provided by an evacuated solar collector field. TRNSYS is used to address the solar aspects of the simulations. For the optimal chiller the driving heat temperature was found to be 121 °C for an evaporator exit temperature of 0 °C. The cooling water flow rate circulating between chiller and cooling tower is 140 l/h. Bubble pump and generator are heated by pressurized water from an insulated tank (70 l/m 2 ) maintained at a maximum temperature of 126 °C – with make-up heat when needed – and storing solar heat at an estimated 4.2 kW power. The solar energy cover only 40% for the energy supplied to drive the chiller. It’s found that the necessary collector surface area is about 6 m 2 with annually total costs of 1.60 €/kW h with 20 years lifetime period for the installation. The avoided CO 2 emissions are estimated at 1396 kg. The equivalent saved energy is 521 l of diesel or 604 l of gasoline

  2. [Qualitative Determination of Organic Vapour Using Violet and Visible Spectrum].

    Science.gov (United States)

    Jiang, Bo; Hu, Wen-zhong; Liu, Chang-jian; Zheng, Wei; Qi, Xiao-hui; Jiang, Ai-li; Wang, Yan-ying

    2015-12-01

    Vapours of organic matters were determined qualitatively employed with ultraviolet-visible absorption spectroscopy. Vapours of organic matters were detected using ultraviolet-visible spectrophotometer employing polyethylene film as medium, the ultraviolet and visible absorption spectra of vegetable oil vapours of soybean oil, sunflower seed oil, peanut oil, rapeseed oil, sesame oil, cotton seed oil, tung tree seed oil, and organic compound vapours of acetone, ethyl acetate, 95% ethanol, glacial acetic acid were obtained. Experimental results showed that spectra of the vegetable oil vapour and the organic compound vapour could be obtained commendably, since ultra violet and visible spectrum of polyethylene film could be deducted by spectrograph zero setting. Different kinds of vegetable oils could been distinguished commendably in the spectra since the λ(max), λ(min), number of absorption peak, position, inflection point in the ultra violet and visible spectra obtained from the vapours of the vegetable oils were all inconsistent, and the vapours of organic compounds were also determined perfectly. The method had a good reproducibility, the ultraviolet and visible absorption spectra of the vapours of sunflower seed oil in 10 times determination were absolutely the same. The experimental result indicated that polyethylene film as a kind of medium could be used for qualitative analysis of ultraviolet and visible absorption spectroscopy. The method for determination of the vapours of the vegetable oils and organic compounds had the peculiarities of fast speed analysis, well reproducibility, accuracy and reliability and low cost, and so on. Ultraviolet and visible absorption spectrum of organic vapour could provide feature information of material vapour and structural information of organic compound, and provide a novel test method for identifying vapour of compound and organic matter.

  3. Preventive maintenance basis: Volume 19 -- HVAC -- chillers and compressors. Final report

    International Nuclear Information System (INIS)

    Worledge, D.; Hinchcliffe, G.

    1997-12-01

    US nuclear power plants are implementing preventive maintenance (PM) tasks with little documented basis beyond fundamental vendor information to support the tasks or their intervals. The Preventive Maintenance Basis project provides utilities with the technical basis for PM tasks and task intervals associated with 40 specific components such as valves, electric motors, pumps, and HVAC equipment. This document provides a program of preventive maintenance tasks suitable for application to HVAC -- Chillers and Compressors. The PM tasks that are recommended provide a cost-effective way to intercept the causes and mechanisms that lead to degradation and failure. They can be used in conjunction with material from other sources, to develop a complete PM program or to improve an existing program

  4. Experimental studies of solar heat pipe used to operate absorption chiller in conditions of Vietnam

    Energy Technology Data Exchange (ETDEWEB)

    Hiep, Le Chi [Ho Chi Minh City Univ. of Tech., Ho Chi Minh City (Viet Nam); Quoc, Hoang An [Ho Chi Minh City Univ. of Tech. Education, Ho Chi Minh City (Viet Nam); Hung, Hoang Duong [Danang Univ. of Tech., Danang City (Viet Nam)

    2008-07-01

    Several models of solar heat pipe have been fabricated and tested. The experiments show that the flat plate model could be used to operate absorption chiller in the climate of southern part of Vietnam. Two main advantages of the selected solar heat pipe are low cost and easy fabrication at local conditions. It is expected that the selected solar heat pipe could attract attention of the community to develop the application of solar energy in Vietnam. Based on the current demand, the paper presents the experimental studies of the first generation of low cost solar heat pipe. The paper also discusses the ability of application of solar air conditioning in Vietnam and recommends the suitable diagram mixing solar energy with other heat source to operate stably the system. (orig.)

  5. Assessing the microbiomes of scalder and chiller tank waters throughout a typical commercial poultry processing day.

    Science.gov (United States)

    Rothrock, M J; Locatelli, A; Glenn, T C; Thomas, J C; Caudill, A C; Kiepper, B H; Hiett, K L

    2016-10-01

    The commercial poultry processing environment plays a significant role in reducing foodborne pathogens and spoilage organisms from poultry products prior to being supplied to consumers. While understanding the microbiological quality of these products is essential, little is known about the microbiota of processing water tanks within the processing plant. Therefore, the goal of this study was to assess the microbiomes of the scalder and chiller tanks during a typical commercial processing d, and determine how bacterial populations, including foodborne pathogens and spoilage organisms, change during the processing day in relation to the bacterial communities as a whole. Additionally, considering this is the first microbiomic analysis of processing tank waters, 2 water sampling methods also were compared. Results of this study show that Proteobacteria and Firmicutes represented over half of the sequences recovered from both tanks at the phylum level, but the microbiomic profiles needed to be analyzed at the genus level to observe more dynamic population shifts. Bacteria known to predominate in the live production environment were found to increase in the scalder tank and gram negative spoilage-related bacteria were found to decrease in the chiller tank throughout the processing day. Directly sampling the scalder water, as compared to analyzing filtered samples, resulted in significantly different microbiomic profiles dominated by Anoxybacillus species. While no sequences related to major foodborne pathogens were found, further sampling collection and processing optimization should provide researchers and the poultry industry a new tool to understand the ecological role of spoilage and pathogenic bacteria within processing tank waters. Published by Oxford University Press on behalf of Poultry Science Association 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  6. Advanced cogeneration and absorption chillers potential for service to Navy bases. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, J.W.; Butcher, T.A.; Leigh, R.W.; McDonald, R.J.; Pierce, B.L.

    1996-04-01

    The US military uses millions of Btu`s of thermal energy to heat, cool and deliver process thermal energy to buildings on military bases, much of which is transmitted through a pipeline system incorporating thousands of miles of pipe. Much of this pipeline system is in disrepair and is nearing the end of its useful life, and the boilers which supply it are old and often inefficient. In 1993, Brookhaven National Laboratory (BNL) proposed to SERDP a three-year effort to develop advanced systems of coupled diesel cogenerators and absorption chillers which would be particularly useful in providing a continuation of the services now provided by increasingly antiquated district systems. In mid-February, 1995, BNL learned that all subsequent funding for our program had been canceled. BNL staff continued to develop the Program Plan and to adhere to the requirements of the Execution Plan, but began to look for ways in which the work could be made relevant to Navy and DoD energy needs even without the extensive development plan formerly envisioned. The entire program was therefore re-oriented to look for ways in which small scale cogeneration and absorption chilling technologies, available through procurement rather than development, could provide some solutions to the problem of deteriorated district heating systems. The result is, we believe, a striking new approach to the provision of building services on military bases: in many cases, serious study should be made of the possibility that the old district heating system should be removed or abandoned, and small-scale cogenerators and absorption chillers should be installed in each building. In the remainder of this Summary, we develop the rationale behind this concept and summarize our findings concerning the conditions under which this course of action would be advisable and the economic benefits which will accrue if it is followed. The details are developed in the succeeding sections of the report.

  7. Modelling of vapour explosion in stratified geometrie

    International Nuclear Information System (INIS)

    Picchi, St.

    1999-01-01

    When a hot liquid comes into contact with a colder volatile liquid, one can obtain in some conditions an explosive vaporization, told vapour explosion, whose consequences can be important on neighbouring structures. This explosion needs the intimate mixing and the fine fragmentation between the two liquids. In a stratified vapour explosion, these two liquids are initially superposed and separated by a vapor film. A triggering of the explosion can induce a propagation of this along the film. A study of experimental results and existent models has allowed to retain the following main points: - the explosion propagation is due to a pressure wave propagating through the medium; - the mixing is due to the development of Kelvin-Helmholtz instabilities induced by the shear velocity between the two liquids behind the pressure wave. The presence of the vapour in the volatile liquid explains experimental propagation velocity and the velocity difference between the two fluids at the pressure wave crossing. A first model has been proposed by Brayer in 1994 in order to describe the fragmentation and the mixing of the two fluids. Results of the author do not show explosion propagation. We have therefore built a new mixing-fragmentation model based on the atomization phenomenon that develops itself during the pressure wave crossing. We have also taken into account the transient aspect of the heat transfer between fuel drops and the volatile liquid, and elaborated a model of transient heat transfer. These two models have been introduced in a multi-components, thermal, hydraulic code, MC3D. Results of calculation show a qualitative and quantitative agreement with experimental results and confirm basic options of the model. (author)

  8. Water vapour measurements during POLINAT 1

    Energy Technology Data Exchange (ETDEWEB)

    Ovarlez, J.; Ovarlez, H. [Centre National de la Recherche Scientifique, 91 - Palaiseau (France). Lab. de Meteorologie Dynamique

    1997-12-31

    The POLINAT (POLlution from aircraft emissions In the North ATlantic flight corridor)1 experiment has been performed within the framework of the Environment Programme of the Commission of the European Community. It was devoted to the study of the pollution from aircraft in the North Atlantic flight corridor, in order to investigate the impact of pollutants emitted by aircraft on the concentrations of ozone and other trace gases in the upper troposphere and lower stratosphere. For that experiment the water vapour content was measured with a frost-point hygrometer on board of the DLR Falcon research aircraft. This instrument is described, and some selected results are given. (author) 19 refs.

  9. Copper vapour laser development for Silva

    International Nuclear Information System (INIS)

    Bettinger, A.; Neu, M.; Chatelet, J.

    1993-01-01

    The recent developments of the components for high power Copper Vapour Laser (CVL) have been oriented towards four main goals: high quality laser beam, mainly for the CVL oscillators, increase of the extracted energy out of the amplifying stage, fully integrated and monolithic design for oscillator and amplifier, extended lifetime and high reliability. A first step of this work, which is done under contract with CILAS (Compagnie Industrielle des Lasers) led to an injection seeded oscillator and a 100 Watts amplifier; the present step concerns development of a 400 Watts class amplifier

  10. Water vapour measurements during POLINAT 1

    Energy Technology Data Exchange (ETDEWEB)

    Ovarlez, J; Ovarlez, H [Centre National de la Recherche Scientifique, 91 - Palaiseau (France). Lab. de Meteorologie Dynamique

    1998-12-31

    The POLINAT (POLlution from aircraft emissions In the North ATlantic flight corridor)1 experiment has been performed within the framework of the Environment Programme of the Commission of the European Community. It was devoted to the study of the pollution from aircraft in the North Atlantic flight corridor, in order to investigate the impact of pollutants emitted by aircraft on the concentrations of ozone and other trace gases in the upper troposphere and lower stratosphere. For that experiment the water vapour content was measured with a frost-point hygrometer on board of the DLR Falcon research aircraft. This instrument is described, and some selected results are given. (author) 19 refs.

  11. Thermogravimetric studies of vapour-aerosol interactions

    International Nuclear Information System (INIS)

    Henshaw, J.; Newland, M.S.; Wood, S.J.

    1991-01-01

    Thermogravimetric analysis has been used to study the interaction of iodine vapour with cadmium, silver and manganese monoxide substrates. These studies have demonstrated the importance of time-dependence data on reaction rates. Iodine did not react with manganese monoxide (as expected from thermodynamic considerations); however, extensive reaction did occur with silver and cadmium. Two rate limiting mechanisms were observed: mass transfer of iodine molecules from the gas phase (leading to linear reaction rates) and parabolic kinetics (ie inversely proportional to the extent of reaction) when the rate was limited by a diffusion process through the reaction product. (author)

  12. Experiments on a vapour absorption heat transformer

    Energy Technology Data Exchange (ETDEWEB)

    George, J M; Murthy, S S [Indian Inst. of Tech., Madras (India). Dept. of Mechanical Engineering

    1993-03-01

    Tests were conducted on a 3 kW heating capacity R21-DMF vapour absorption heat transformer to study the influence of operating temperature on its performance. Heat source temperature and condensing temperature were varied in the ranges 50-75[sup o]C and 20-40[sup o]C, respectively. Heat delivery temperatures up to 85[sup o]C and temperature lifts up to 20[sup o]C were achieved. Actual coefficients of performance (COPs) ranged from 0.2 to 0.35, whereas exergetic efficiencies of 0.3-0.4 could be obtained. (Author)

  13. Technical committee meeting on aerosol formation, vapour deposits and sodium vapour trapping. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1977-01-01

    The papers presented at the LMFBR meeting on aerosol formation covered the following four main topics: theoretical studies on aerosol behaviour and comparison with experimental results; techniques for measurement of aerosols; techniques for trapping sodium vapour and aerosols in gas circuits; design of components having to cope with aerosol deposits. The resulting summaries, conclusions and recommendations which were were agreed upon are presented.

  14. Technical committee meeting on aerosol formation, vapour deposits and sodium vapour trapping. Summary report

    International Nuclear Information System (INIS)

    1977-01-01

    The papers presented at the LMFBR meeting on aerosol formation covered the following four main topics: theoretical studies on aerosol behaviour and comparison with experimental results; techniques for measurement of aerosols; techniques for trapping sodium vapour and aerosols in gas circuits; design of components having to cope with aerosol deposits. The resulting summaries, conclusions and recommendations which were were agreed upon are presented

  15. Performance Evaluation of a Continuous Operation Adsorption Chiller Powered by Solar Energy Using Silica Gel and Water as the Working Pair

    OpenAIRE

    Hassan, Hassan

    2014-01-01

    In the present study, dynamic analysis and performance evaluation of a solar-powered continuous operation adsorption chiller are introduced. The adsorption chiller uses silica gel and water as the working pair. The developed mathematical model represents the heat and mass transfer within the reactor coupled with the energy balance of the collector plate and the glass cover. Moreover, a non-equilibrium adsorption kinetic model is taken into account by using the linear driving force equation. T...

  16. Collective dynamics in dense Hg vapour

    International Nuclear Information System (INIS)

    Ishikawa, D; Inui, M; Matsuda, K; Tamura, K; Baron, A Q R; Tsutsui, S; Tanaka, Y; Ishikawa, T

    2004-01-01

    The dynamic structure factor, S(Q,ο), of dense Hg vapour has been measured by high resolution inelastic x-ray scattering for densities of 3.0, 2.1 and 1.0 g cm -3 corresponding to 0.52, 0.36 and 0.17 times the critical density, respectively, and for momentum transfers between 2.0 and 48 nm -1 . Analysis of the longitudinal current-current correlation function in the framework of generalized hydrodynamics reveals that the frequencies of the collective excitations increase faster with Q than estimated from the macroscopic speed of sound. The ratios of the frequencies were found to be 1.27 at 3.0 g cm -3 , 1.12 at 2.1 g cm -3 and 1.10 at 1.0 g cm -3 . The sound velocity obtained from the present experiments is well reproduced by a wavenumber dependent adiabatic sound velocity, which means that the collective modes remain in the spectra of dense Hg vapour. (letter to the editor)

  17. Transient modeling of an air-cooled chiller with economized compressor. Part II: Application to control design

    International Nuclear Information System (INIS)

    Zhang Weijiang; Ding Shufu; Zhang Chunlu

    2009-01-01

    Based on the transient modeling developed in the previous paper, the control design of the air-cooled chiller is studied. The main electronic expansion valve (EXV) controls the suction superheat, the compressor controls the leaving water temperature and the sub EXV regulates the injection superheat. Since the system reliability is sensitive to the control of the suction superheat, it is the focus in this paper. Dynamic simulation cases are built to compare two control algorithms, PID and fuzzy logic. The case studies show that the fuzzy controller has higher reliability and performance. Both the two controllers are fully tested and tuned on a chiller test facility and the experiments indicate that the fuzzy controller works better as well.

  18. Solar heating and cooling system with absorption chiller and low temperature latent heat storage: Energetic performance and operational experience

    Energy Technology Data Exchange (ETDEWEB)

    Helm, M.; Keil, C.; Hiebler, S.; Mehling, H.; Schweigler, C. [Bavarian Center for Applied Energy Research (ZAE Bayern) (Germany)

    2009-06-15

    Absorption cooling systems based on water/lithium bromide (LiBr) solution typically require an open wet cooling tower to transfer the reject heat to the ambient. Yet, water consumption, the need for water make-up and cleaning, formation of fog, and the risk of Legionella bacteria growth are hindering factors for the implementation of small solar cooling systems. The application of a latent heat storage supporting the heat rejection of the absorption chiller in conjunction with a dry cooling system allows eliminating the wet cooling tower. By that means heat rejection of the chiller is shifted to periods with lower ambient temperatures, i.e. night time or off-peak hours. The system concept and the hydraulic scheme together with an analysis of the energetic performance of the system are presented, followed by a report on the operation of a first pilot installation. (author)

  19. Lower operating cost due to compressed-air recirculation

    Energy Technology Data Exchange (ETDEWEB)

    Schauwecker, F

    1979-01-01

    Compressed air containing dirt and aggressive substances may cause damage in pipelines and pneumatic tools, equipment and systems. In consequence, operating costs can be greatly reduced by cleaning and recirculation of compressed air. Compressed-air driers are among the most common systems used for this purpose. Most of these driers are refrigeration driers; adsorption driers are less common. Refrigeration driers consist of a heat exchanger system, a separation system, and a power-controlled refrigerator. The water vapour concentration is proportional to the air temperature; for this reason, the pressure dew point should be as low as possible, i.e. about 1.5/sup 0/C.

  20. Modeling and simulation of chillers with Dymola/Modelica; Modellierung und Simulation von Kaeltemaschinen mit Dymola/Modelica

    Energy Technology Data Exchange (ETDEWEB)

    Rettich, Daniel [Hochschule Biberach (Germany). Inst. fuer Gebaeude- und Energiesysteme (IGE)

    2012-07-01

    Within the contribution under consideration, a chiller was modeled and simulated with the program package Dymola / Modelica using the TIL Toolbox. An existing refrigeration technology test bench at the University of Biberach (Federal Republic of Germany) serves as a reference for the chiller illustrated in the simulation. The aim of the simulation is the future use of the models in a hardware-in-the-Loop (HIL) test bench in order to test different controllers with respect to their function and logic under identical framework conditions. Furthermore, the determination of the energy efficiency according to the regulation VDMA 24247 is in the foreground at the test bench as well as within the simulation. Following the final completion of the test bench, the models are validated against the test bench, and the model of the refrigerator will be connected to a detailed space model. Individual models were taken from the TIL toolbox, adapted for the application and parameterized with the design values of the laboratory chiller. Modifications to the TIL models were necessary in order to reflect the dynamic effects of the chiller in detail. For this purpose, investigations on indicators of the various dynamic components were employed. Subsequently to the modeling, each model was tested on the bases of design values and documents of the manufacturer. First simulation studies showed that the simulation in Dymola including the developed models provide plausible results. In the course of the modeling and parameterization of these modified models a component library was developed. Different models for future simulation studies can be extracted.

  1. Evaluation of Carcass Quality for Coliforms, Salmonella and Psychrophiles on Evisceration and Chiller lines in Yazd Province Industrial Poultry Slaughterhouses

    Directory of Open Access Journals (Sweden)

    M Mofidi

    2014-05-01

    In general, it can be said that secondary contamination in the slaughter line along with gradual increase in temperature of the chiller can increase bacterial load of both coliforms and salmonella but it will not affect the amount of psychrophile bacteria. Due to some differences between the studied slaughterhouses, microbial load of coliform and salmonella can be acheived by improving the management and installation of appropriate aquipments in the evisceration line.

  2. Estimation of vapour pressure and partial pressure of subliming ...

    Indian Academy of Sciences (India)

    Administrator

    conditions of (total) pressure by using thermogravimetry under those conditions. Further, from the partial pressure P, it is possible to determine the number of moles of material in the vapour phase using the ideal gas equation, PV = nRT, where P is the partial pressure, V the volume, n number of moles (of the vapour), R the ...

  3. Beam-profile monitor using a sodium-vapour

    CERN Multimedia

    1972-01-01

    Beam-profile monitor using a sodium-vapour curtain at 45 degrees to the ISR beam in Ring I (sodium generator is in white cylinder just left of centre). Electrons produced by ionization of the sodium vapour give an image of the beam on a fluorescent screen that is observed by a TV camera (at upper right).

  4. Hot-wire chemical vapour deposition of carbon nanotubes

    CSIR Research Space (South Africa)

    Cummings, FR

    2006-07-01

    Full Text Available ablation of graphite, carbon-arc discharge and chemical vapour deposition (CVD). However, some of these techniques have been shown to be expensive due to high deposition temperatures and are not easily controllable. Recently hot-wire chemical vapour...

  5. Capacitive-discharge-pumped copper bromide vapour laser

    International Nuclear Information System (INIS)

    Sukhanov, V B; Fedorov, V F; Troitskii, V O; Gubarev, F A; Evtushenko, Gennadii S

    2007-01-01

    A copper bromide vapour laser pumped by a high-frequency capacitive discharge is developed. It is shown that, by using of a capacitive discharge, it is possible to built a sealed off metal halide vapour laser of a simple design allowing the addition of active impurities into the working medium. (letters)

  6. A systematic parametric study and feasibility assessment of solar-assisted single-effect, double-effect, and triple-effect absorption chillers for heating and cooling applications

    International Nuclear Information System (INIS)

    Shirazi, Ali; Taylor, Robert A.; White, Stephen D.; Morrison, Graham L.

    2016-01-01

    Highlights: • TRNSYS simulations of SHC single/multi-effect absorption chillers were conducted. • A detailed parametric study was conducted to find the optimal size of the tank. • The effect of tank heat loss on the performance of the configurations was analyzed. • The effect of beam and diffuse radiation on the solar field size was investigated. • Energy performance and economics of each plant were analyzed in various climates. - Abstract: The present work investigates the feasibility of solar heating and cooling (SHC) absorption systems based on combining three types of LiBr–H_2O absorption chillers (single-, double-, and triple-effect) with common solar thermal collectors available on the market. A single-effect chiller is coupled with evacuated tube collectors (ETCs) – SHC1. A double-effect chiller is integrated with parabolic trough collectors (PTCs), linear Fresnel micro-concentrating collectors (MCTs) and evacuated flat plate collectors (EFPCs) respectively – SHC2, SHC3, and SHC4. PTCs are employed to provide high-temperature heat to a triple-effect absorption chiller (SHC5). Although triple-effect chillers have been around for a while, this paper represents the first system-level analysis of these chillers coupled with high-temperature solar concentrating collectors for air-conditioning applications. A simulation model for each configuration is developed in a transient system simulation environment (TRNSYS 17). Furthermore, a unique, comprehensive perspective is given by investigating the impact of characteristic solar beam radiation to global radiation ratios on the techno-economic performance of the proposed SHC plants for a wide variety of climatic regions worldwide. The results of parametric study suggest that a storage volume of around 70 L/m"2 is a good choice for SHC1, while 40–50 L/m"2 storage capacity is sufficient for the other configurations (SHC2 to SHC5). The simulation results reveal that when the fraction of direct normal

  7. Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

    KAUST Repository

    Vakarelski, Ivan Uriev

    2012-09-12

    In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling-by heat transfer-the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating. © 2012 Macmillan Publishers Limited. All rights reserved.

  8. Stabilization of Leidenfrost vapour layer by textured superhydrophobic surfaces

    KAUST Repository

    Vakarelski, Ivan Uriev; Patankar, Neelesh A.; Marston, Jeremy; Chan, Derek Y C; Thoroddsen, Sigurdur T

    2012-01-01

    In 1756, Leidenfrost observed that water drops skittered on a sufficiently hot skillet, owing to levitation by an evaporative vapour film. Such films are stable only when the hot surface is above a critical temperature, and are a central phenomenon in boiling. In this so-called Leidenfrost regime, the low thermal conductivity of the vapour layer inhibits heat transfer between the hot surface and the liquid. When the temperature of the cooling surface drops below the critical temperature, the vapour film collapses and the system enters a nucleate-boiling regime, which can result in vapour explosions that are particularly detrimental in certain contexts, such as in nuclear power plants. The presence of these vapour films can also reduce liquid-solid drag. Here we show how vapour film collapse can be completely suppressed at textured superhydrophobic surfaces. At a smooth hydrophobic surface, the vapour film still collapses on cooling, albeit at a reduced critical temperature, and the system switches explosively to nucleate boiling. In contrast, at textured, superhydrophobic surfaces, the vapour layer gradually relaxes until the surface is completely cooled, without exhibiting a nucleate-boiling phase. This result demonstrates that topological texture on superhydrophobic materials is critical in stabilizing the vapour layer and thus in controlling-by heat transfer-the liquid-gas phase transition at hot surfaces. This concept can potentially be applied to control other phase transitions, such as ice or frost formation, and to the design of low-drag surfaces at which the vapour phase is stabilized in the grooves of textures without heating. © 2012 Macmillan Publishers Limited. All rights reserved.

  9. Thermoeconomic and environmental analyses of a low water consumption combined steam power plant and refrigeration chillers – Part 1: Energy and economic modelling and analysis

    International Nuclear Information System (INIS)

    Ifaei, Pouya; Rashidi, Jouan; Yoo, ChangKyoo

    2016-01-01

    Highlights: • Proposing two energy systems by combining refrigeration chillers and power plants. • Model-based comparison of the systems through energy and economic standpoints. • Reducing total annual costs of the base system up to 4.7% by process integration. • Decreasing the water loss in wet cooling towers by up to 18% in the proposed system. • Suggesting a water-fuel economic management strategy based on parametric analysis. - Abstract: Two novel configurations are proposed to replace the conventional Rankine cycle based steam power plants (SPP) with natural draft wet cooling towers (NDWCT) as cooling units. Closed feedwater heater unit of the base SPP-NDWCT system is eliminated in order to combine a vapor compression refrigeration (VCR) and an absorption heat pump (ABHP) with the base SPP-NDWCT system. Both VCR-SPP-NDWCT and ABHP-SPP-NDWCT systems are integrated to decrease the NDWCT load which could result in water losses decrease. In part one of the presented two-part paper, model-based energy and economic analyses are performed to compare systems performance and applicability. The temperature difference at pinch point and temperature difference between the hot and cold sides of the heat exchangers which were used for systems integration in VCR-SPP-NDWCT, and the absorber pressure and temperature in ABHP-SPP-NDWCT system are studied using parametric analysis procedure. A water-fuel management strategy is also introduced for the ABHP-SPP-NDWCT system according to the influence of the absorber pressure changes on system water and fuel consumption. In part 2, environmental and thermoeconomic analyses are performed to complete a comprehensive study on designing steam power plants. The results of part 1 showed that water losses and total annual costs decreased by 1–18% and 0–4.7% for the ABHP-SPP-NDWCT system but increased by 11% and 60% for the VCR-SPP-NDWCT system, respectively.

  10. Wellhead compression

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, Joe [Sertco Industries, Inc., Okemah, OK (United States); Vazquez, Daniel [Hoerbiger Service Latin America Inc., Deerfield Beach, FL (United States); Jacobs, Denis Richard [Hoerbiger do Brasil Industria de Equipamentos, Cajamar, SP (Brazil)

    2012-07-01

    Over time, all wells experience a natural decline in oil and gas production. In gas wells, the major problems are liquid loading and low downhole differential pressures which negatively impact total gas production. As a form of artificial lift, wellhead compressors help reduce the tubing pressure resulting in gas velocities above the critical velocity needed to surface water, oil and condensate regaining lost production and increasing recoverable reserves. Best results come from reservoirs with high porosity, high permeability, high initial flow rates, low decline rates and high total cumulative production. In oil wells, excessive annulus gas pressure tends to inhibit both oil and gas production. Wellhead compression packages can provide a cost effective solution to these problems by reducing the system pressure in the tubing or annulus, allowing for an immediate increase in production rates. Wells furthest from the gathering compressor typically benefit the most from wellhead compression due to system pressure drops. Downstream compressors also benefit from higher suction pressures reducing overall compression horsepower requirements. Special care must be taken in selecting the best equipment for these applications. The successful implementation of wellhead compression from an economical standpoint hinges on the testing, installation and operation of the equipment. Key challenges and suggested equipment features designed to combat those challenges and successful case histories throughout Latin America are discussed below.(author)

  11. Tri-generation System based on Municipal Waste Gasification, Fuel Cell and an Absorption Chiller

    Directory of Open Access Journals (Sweden)

    Giannis Katsaros

    2018-03-01

    Full Text Available The present work focuses on the design of a novel tri-generation system based on gasification of municipal solid wastes, a solid oxide fuel cell and an ammonia-water absorption chiller. Tri-generation systems can be implemented in buildings such as hospitals and hotels, where there is a continuous and large demand for electricity, heating and cooling. The system is modelled in Aspen Plus and the influence of different operating parameters on the system performance was studied. The findings suggest that low air equivalent ratios and high gasification temperatures enhance the overall system performance. Syngas cleaning with metal sorbents zinc oxide and sodium bicarbonate for the removal of hydrogen sulfide and hydrogen chloride concentrations proved to be very effective, reducing the concentration of contaminants to < 1 ppm (part per million levels. The possibility of covering the demand profiles of a specific building was also investigated: the system could fully meet the electricity and cooling demands, whereas the heat requirements could be satisfied only up to 55%. Moreover, assuming 20 years of operation, the payback period was 4.5 years and the net present value exceeded 5 million euros.

  12. Effect of the switching time on the performance of an adsorption chiller

    International Nuclear Information System (INIS)

    Hong, Sang Woo; Chung, Jae Dong; Kwon, Oh Kyung

    2016-01-01

    The switching time is an important operating condition that must be correctly anticipated for an effective adsorption cooling system. Before the adsorption (or desorption) process begins, time is required to cool down (or heat up) the bed temperature so that the bed pressure reaches the evaporator pressure (or condenser pressure). During the switching time, the supplied heat is reduced and pressure overload conditions can be avoided. The switching time cannot be estimated early on, and an improper switching time degrades the system performance. Thus, this study provides guideline with which to determine the required time to open this valve, i.e., the switching time, and carefully examines the thermo-physical behavior in the adsorption bed during this period. A two-dimensional numerical method with the composite sorbent of SWS-1L and a water pair is applied to a fin-tube type adsorption chiller. Three cases of no switching time, the optimal switching time and a double the optimal switching time are examined. The results show that no consideration of the switching time overestimates the performance of the adsorption cooling system in terms of the Coefficient of performance (COP) and the Specific cooling power (SCP). On the other hand, if the switching time exceeds the optimal value, the performance of the adsorption cooling system is also reduced compared to that when using the optimal switching time. The dependency of the optimal switching times on various design parameters, such as the fin pitch, fin height and heating temperature, is also examined.

  13. Model-based optimization strategy of chiller driven liquid desiccant dehumidifier with genetic algorithm

    International Nuclear Information System (INIS)

    Wang, Xinli; Cai, Wenjian; Lu, Jiangang; Sun, Youxian; Zhao, Lei

    2015-01-01

    This study presents a model-based optimization strategy for an actual chiller driven dehumidifier of liquid desiccant dehumidification system operating with lithium chloride solution. By analyzing the characteristics of the components, energy predictive models for the components in the dehumidifier are developed. To minimize the energy usage while maintaining the outlet air conditions at the pre-specified set-points, an optimization problem is formulated with an objective function, the constraints of mechanical limitations and components interactions. Model-based optimization strategy using genetic algorithm is proposed to obtain the optimal set-points for desiccant solution temperature and flow rate, to minimize the energy usage in the dehumidifier. Experimental studies on an actual system are carried out to compare energy consumption between the proposed optimization and the conventional strategies. The results demonstrate that energy consumption using the proposed optimization strategy can be reduced by 12.2% in the dehumidifier operation. - Highlights: • Present a model-based optimization strategy for energy saving in LDDS. • Energy predictive models for components in dehumidifier are developed. • The Optimization strategy are applied and tested in an actual LDDS. • Optimization strategy can achieve energy savings by 12% during operation

  14. Numerical simulation of bubbles motion in lifting pipe of bubble pump for lithium bromide absorption chillers

    International Nuclear Information System (INIS)

    Gao, Hongtao; Liu, Bingbing; Yan, Yuying

    2017-01-01

    A bubble pump is proposed to replace the traditional mechanical solution pump in lithium bromide absorption chillers, for its advantageous feature that can be driven by industrial waste heat or solar energy or other low-grade energy. In two-stage bubble pump driven lithium bromide absorption refrigeration system, flow patterns in lifting pipe have significant effects on the performance of bubble pump. In this paper, the single bubble motion and the double bubbles coalescence in vertical ascending pipe are simulated by an improved free energy model of lattice Boltzmann method, in which the two-phase liquid to gas density ratio is 2778. The details of bubbles coalescence process are studied. Density and velocity of bubbles have been obtained. The computational results show that the initial radius of each bubble has a great influence on the coalescence time. The larger the initial bubble radius, the shorter the coalescence time. The pipe diameter has a little effect on the two bubbles coalescence time while it has a significant effect on the bubble velocity. As the pipe diameter increases, the bubble velocity increases. The obtained results are helpful for studying the transition mechanisms of two-phase flow patterns and useful for improving the bubble pump performance by controlling the flow patterns in lifting pipe.

  15. Hybrid solar receiver as a source of high-temperature medium for an absorption chiller supply

    Directory of Open Access Journals (Sweden)

    Przenzak Estera

    2016-01-01

    Full Text Available This article discusses the problems related with the cold production, i.e. energy efficiency of the process. The idea of solar cooling systems has been presented as the solution of the problem of big electricity demand. The paper discusses the principle of the operation of absorption chillers. Disadvantages and advantages of the solar cooling systems were discussed. The installation for manufacturing high-temperature heat based on solar collectors and concentrator of solar radiation constructed in AGH in Cracow has been presented. This installation is a first stage of projected, complete solar cooling system. The special attention is paid to the dedicated solar high-temperature heat receiver as a most important element of the system. The achieved values of temperature, power and efficiency depending on the working medium flow has been presented and discussed. The intensity of solar radiation during the measurements has been taken into account. Two versions of heat receiver were investigated: non-insulated and insulated with mineral wool. The obtained efficiency of the heat receiver (less than 30% is not satisfactory but possibility of improvements exist.

  16. Effect of the switching time on the performance of an adsorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sang Woo; Chung, Jae Dong [Sejong University, Seoul (Korea, Republic of); Kwon, Oh Kyung [Korea Institute of Industrial Technology, Chonan (Korea, Republic of)

    2016-05-15

    The switching time is an important operating condition that must be correctly anticipated for an effective adsorption cooling system. Before the adsorption (or desorption) process begins, time is required to cool down (or heat up) the bed temperature so that the bed pressure reaches the evaporator pressure (or condenser pressure). During the switching time, the supplied heat is reduced and pressure overload conditions can be avoided. The switching time cannot be estimated early on, and an improper switching time degrades the system performance. Thus, this study provides guideline with which to determine the required time to open this valve, i.e., the switching time, and carefully examines the thermo-physical behavior in the adsorption bed during this period. A two-dimensional numerical method with the composite sorbent of SWS-1L and a water pair is applied to a fin-tube type adsorption chiller. Three cases of no switching time, the optimal switching time and a double the optimal switching time are examined. The results show that no consideration of the switching time overestimates the performance of the adsorption cooling system in terms of the Coefficient of performance (COP) and the Specific cooling power (SCP). On the other hand, if the switching time exceeds the optimal value, the performance of the adsorption cooling system is also reduced compared to that when using the optimal switching time. The dependency of the optimal switching times on various design parameters, such as the fin pitch, fin height and heating temperature, is also examined.

  17. Economic analysis of solar assisted absorption chiller for a commercial building

    Science.gov (United States)

    Antonyraj, Gnananesan

    Dwindling fossil fuels coupled with changes in global climate intensified the drive to make use of renewable energy resources that have negligible impact on the environment. In this attempt, the industrial community produced various devices and systems to make use of solar energy for heating and cooling of building space as well as generate electric power. The most common components employed for collection of solar energy are the flat plate and evacuated tube collectors that produce hot water that can be employed for heating the building space. In order to cool the building, the absorption chiller is commonly employed that requires hot water at high temperatures for its operation. This thesis deals with economic analysis of solar collector and absorption cooling system to meet the building loads of a commercial building located in Chattanooga, Tennessee. Computer simulations are employed to predict the hourly building loads and performance of the flat plate and evacuated tube solar collectors using the hourly weather data. The key variables affecting the economic evaluation of such system are identified and the influence of these parameters is presented. The results of this investigation show that the flat plate solar collectors yield lower payback period compared to the evacuated tube collectors and economic incentives offered by the local and federal agencies play a major role in lowering the payback period.

  18. Wasted Heat Engine Utilization in Central AC Condenser Type Water Chiller for Economical Energy Water Heaters

    Directory of Open Access Journals (Sweden)

    I Made Rasta

    2012-11-01

    Full Text Available Central AC type water chiller is a refrigeration machine that release heat to environment. Heat energy that released to environment comes from room heat load that absorbed by machine and heat from compressor. The best form in using this loss energy is heat recovery water heater technology, where this machine will take heat from condenser by a heat exchanger to heating water. Refrigerant will flow in the heat exchanger before entering condenser, after that refrigerant flow to other components such as, expansion valve, evaporator, compressor and than return again to condenser, this process will be cycling regularly (closed cycle. Based on experimental and analysis result especially for AC with capacity 2 Pk, and tank capacity 75 liter, with water heater recovery device obtained that: (1 Compressor power consumption decrease from 1.66 kW to 1.59kW. (2 Heat rejected from condenser and used by water heater has ratio 4.683 kJ/s and 1.59 kJ/s, with water heater efficiency is 32.2%. (3 Maximum water temperature can be reached are in range 34oC – 47.5oC in 10-150 minutes and flow rate is 0.5 – 2.5 liter /min

  19. Medical cannabis use in Canada: vapourization and modes of delivery.

    Science.gov (United States)

    Shiplo, Samantha; Asbridge, Mark; Leatherdale, Scott T; Hammond, David

    2016-10-29

    The mode of medical cannabis delivery-whether cannabis is smoked, vapourized, or consumed orally-may have important implications for its therapeutic efficacy and health risks. However, there is very little evidence on current patterns of use among Canadian medical cannabis users, particularly with respect to modes of delivery. The current study examined modes of medical cannabis delivery following regulatory changes in 2014 governing how Canadians access medical cannabis. A total of 364 approved adult Canadian medical cannabis users completed an online cross-sectional survey between April and June 2015. The survey examined patterns of medical cannabis use, modes of delivery used, and reasons for use. Participants were recruited through a convenience sample from nine Health Canada licensed producers. Using a vapourizer was the most popular mode of delivery for medical cannabis (53 %), followed by smoking a joint (47 %). The main reason for using a vapourizer was to reduce negative health consequences associated with smoking. A majority of current vapourizer users reported using a portable vapourizer (67.2 %), followed by a stationary vapourizer (41.7 %), and an e-cigarette or vape pen (19.3 %). Current use of a vapourizer was associated with fewer respiratory symptoms (AOR = 1.28, 95 % CI 1.05-1.56, p = 0.01). The findings suggest an increase in the popularity of vapourizers as the primary mode of delivery among approved medical users. Using vapourizers has the potential to prevent some of the adverse respiratory health consequences associated with smoking and may serve as an effective harm reduction method. Monitoring implications of such current and future changes to medical cannabis regulations may be beneficial to policymakers.

  20. Medical cannabis use in Canada: vapourization and modes of delivery

    Directory of Open Access Journals (Sweden)

    Samantha Shiplo

    2016-10-01

    Full Text Available Abstract Background The mode of medical cannabis delivery—whether cannabis is smoked, vapourized, or consumed orally—may have important implications for its therapeutic efficacy and health risks. However, there is very little evidence on current patterns of use among Canadian medical cannabis users, particularly with respect to modes of delivery. The current study examined modes of medical cannabis delivery following regulatory changes in 2014 governing how Canadians access medical cannabis. Methods A total of 364 approved adult Canadian medical cannabis users completed an online cross-sectional survey between April and June 2015. The survey examined patterns of medical cannabis use, modes of delivery used, and reasons for use. Participants were recruited through a convenience sample from nine Health Canada licensed producers. Results Using a vapourizer was the most popular mode of delivery for medical cannabis (53 %, followed by smoking a joint (47 %. The main reason for using a vapourizer was to reduce negative health consequences associated with smoking. A majority of current vapourizer users reported using a portable vapourizer (67.2 %, followed by a stationary vapourizer (41.7 %, and an e-cigarette or vape pen (19.3 %. Current use of a vapourizer was associated with fewer respiratory symptoms (AOR = 1.28, 95 % CI 1.05–1.56, p = 0.01. Conclusions The findings suggest an increase in the popularity of vapourizers as the primary mode of delivery among approved medical users. Using vapourizers has the potential to prevent some of the adverse respiratory health consequences associated with smoking and may serve as an effective harm reduction method. Monitoring implications of such current and future changes to medical cannabis regulations may be beneficial to policymakers.

  1. Speech Compression

    Directory of Open Access Journals (Sweden)

    Jerry D. Gibson

    2016-06-01

    Full Text Available Speech compression is a key technology underlying digital cellular communications, VoIP, voicemail, and voice response systems. We trace the evolution of speech coding based on the linear prediction model, highlight the key milestones in speech coding, and outline the structures of the most important speech coding standards. Current challenges, future research directions, fundamental limits on performance, and the critical open problem of speech coding for emergency first responders are all discussed.

  2. Vapour galvanizing (Sherardizing) of copper with zinc

    Energy Technology Data Exchange (ETDEWEB)

    Wortelen, Dietbert; Bracht, Hartmut [Westfaelische Wilhelms-Universitaet Muenster (Germany); Natrup, Frank; Graf, Wolfram [Bodycote Waermebehandlung GmbH, Sprockhoevel (Germany)

    2010-07-01

    Using a vapour galvanizing technique called Sherardizing we investigated the growth kinetics and coefficients of zinc copper phases. For this purpose polished (OFHC)-copper plates and zinc powder have been sealed in quartz ampoules under inert gas atmospheres and annealed at a temperature range between 300 and 410 C. In order to study the coating thickness and the phase composition, cross sections were prepared, which have been analyzed by means of optical microscopy and scanning electron microscopy. We were able to demonstrate that the coating thickness is a function of the parabolic time law and that the formed coatings are composed of two layers referring to the ordered {beta}-CuZn and {gamma}-Cu{sub 5}Zn{sub 8}-phases. To enhance the coating quality, small amounts of ZnCl{sub 2} were added to the zinc powder. It was observed that the coating thickness decreased with increasing ZnCl{sub 2}. Experiments with variable Ar-pressure demonstrated a reduced coating growth with increasing pressures. Further measurements with ZnCl{sub 2} were performed to check whether an electrochemical mechanism is involved in the coating process.

  3. Carbon dioxide and water vapour characteristics on the west coast ...

    Indian Academy of Sciences (India)

    Carbon dioxide, water vapour, air temperature and wind measurements at 10 Hz sampling rate were carried out over the ... seasonal and annual variations in the CO2 bal- ance. Hence, it is .... motion below produced by shear stress near the.

  4. Probabilistic risk assessment for six vapour intrusion algorithms

    NARCIS (Netherlands)

    Provoost, J.; Reijnders, L.; Bronders, J.; Van Keer, I.; Govaerts, S.

    2014-01-01

    A probabilistic assessment with sensitivity analysis using Monte Carlo simulation for six vapour intrusion algorithms, used in various regulatory frameworks for contaminated land management, is presented here. In addition a deterministic approach with default parameter sets is evaluated against

  5. Vapour phase synthesis of salol over solid acids via transesterification

    Indian Academy of Sciences (India)

    Administrator

    rate of reactants, WHSV and time-on-stream on the conversion (%) of phenol and selectivity (%) of salol ... Possible reaction mechanisms for the formation of salol and diphenyl ether over ... Hence, vapour-phase conditions of the experiment.

  6. A comprehensive, multi-objective optimization of solar-powered absorption chiller systems for air-conditioning applications

    International Nuclear Information System (INIS)

    Shirazi, Ali; Taylor, Robert A.; Morrison, Graham L.; White, Stephen D.

    2017-01-01

    Highlights: • Multi-objective optimization of solar single/multi-effect absorption chillers was conducted. • Primary energy consumption and total annual cost were considered as the objectives. • Optimized designs of the alternative configurations were compared. • A detailed sensitivity analysis of the Pareto optimal solutions was investigated. - Abstract: Solar heating and cooling (SHC) systems are currently under rapid development and deployment due to their potential to reduce the use of fossil fuel resources and to alleviate greenhouse gas emissions in the building sector – a sector which is responsible for ∼40% of the world energy use. Absorption chiller technology (traditionally powered by natural gas in large buildings), can easily be retrofitted to run on solar energy. However, numerous non-intuitive design choices must be analyzed to achieve the best techno-economic performance of these systems. To date, there has been little research into the optimal configurations among the long list of potential solar-driven absorption chiller systems. To address this lack of knowledge, this paper presents a systematic simulation-based, multi-objective optimization of three common, commercially available lithium bromide-water absorption chillers – single-effect, double-effect and triple-effect – powered by evacuated tube collectors (ETCs), evacuated flat plate collectors (EFPCs), and concentrating parabolic trough collectors (PTCs), respectively. To the best of authors’ knowledge, this is the first study of its kind that compares the optimized designs of the most promising configurations of solar-assisted absorption chillers against a common set of energy, economic, and environmental metrics from a holistic perspective. A simulation model of these three configurations is developed using TRNSYS 17. A combined energy, economic, and environmental analysis of the modeled systems is conducted to calculate the primary energy use as well as the levelized total

  7. Ethylene vinylacetate copolymer and nanographite composite as chemical vapour sensor

    International Nuclear Information System (INIS)

    Stepina, Santa; Sakale, Gita; Knite, Maris

    2013-01-01

    Polymer-nanostructured carbon composite as chemical vapour sensor is described, made by the dissolution method of a non-conductive polymer, ethylene vinylacetate copolymer, mixed with conductive nanographite particles (carbon black). Sensor exhibits relative electrical resistance change in chemical vapours, like ethanol and toluene. Since the sensor is relatively cheap, easy to fabricate, it can be used in air quality monitoring and at industries to control hazardous substance concentration in the air, for example, to protect workers from exposure to chemical spills

  8. Microsphere formation in droplets using antisolvent vapour precipitation technique

    OpenAIRE

    Chew, Sean Jun Liang

    2017-01-01

    In previous studies, the antisolvent vapour precipitation method has been proven to produce uniformly sized lactose microspheres (1.0 µm) from a single droplet (1.2 mm diameter) at atmospheric pressure. These types of particles have potential applications in the pharmaceutical industry, especially due to their high dissolution rate. This project looked into the possibility of using antisolvent vapour precipitation to produce microspheres from finely atomised droplets. Microspheres in the sub-...

  9. Brain temperature profiles during epidural cooling with the ChillerPad in a monkey model of traumatic brain injury.

    Science.gov (United States)

    King, Christopher; Robinson, Timothy; Dixon, C Edward; Rao, Gutti R; Larnard, Donald; Nemoto, C Edwin M

    2010-10-01

    Therapeutic hypothermia remains a promising treatment for patients with severe traumatic brain injury (TBI). Multiple animal studies have suggested that hypothermia is neuroprotective after TBI, but clinical trials have been inconclusive. Systemic hypothermia, the method used in almost all major clinical trials, is limited by the time to target temperature, the depth of hypothermia, and complications, problems that may be solved by selective brain cooling. We evaluated the effects on brain temperature of a cooling device called the ChillerPad,™ which is applied to the dura in a non-human primate TBI model using controlled cortical impact (CCI). The cortical surface was rapidly cooled to approximately 15°C and maintained at that level for 24 h, followed by rewarming over about 10 h. Brain temperatures fell to 34-35°C at a depth of 15 mm at the cortical gray/white matter interface, and to 28-32°C at 10 mm deep. Intracranial pressure was mildly elevated (8-12 mm Hg) after cooling and rewarming, likely due to TBI. Other physiological variables were unchanged. Cooling was rapidly diminished at points distant from the cooling pad. The ChillerPad may be useful for highly localized cooling of the brain in circumstances in which a craniotomy is clinically indicated. However, because of the delay required by the craniotomy, other methods that are more readily available for inducing hypothermia may be used as a bridge between the time of injury to placement of the ChillerPad.

  10. Thermal analysis and modeling of a swimming pool heating system by utilizing waste energy rejected from a chiller unit of an ice rink

    Directory of Open Access Journals (Sweden)

    Kuyumcu Muhammed Enes

    2017-01-01

    Full Text Available This study deals with the thermal analysis and modeling of a swimming pool heating system in which the waste energy rejected from the chiller unit of an ice rink is used as an energy source. The system consists of a swimming pool and an ice rink coupled by a chiller unit. The swimming pool and the ice rink both indoor types and were constructed in city of Gaziantep, Turkey. The thermal energy requirement for each section is determined by thermal analysis of each component of the system. Effects of different design parameters such as ceiling insulation thickness, ceiling emissivity, Carnot efficiency factor and size of the ice rink on the thermal energy requirements and coefficient of performance of the chiller unit are investigated. As a result of analyses of the system, the minimum ice rink area is determined in order to meet annual total heat energy demand of the olympic-sized swimming pool.

  11. Considering the use of polyethylene vapour barriers in temperate climates

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, M.D. [Morrison Hershfield Ltd., Vancouver, BC (Canada); Brown, W.C. [Morrison Hershfield Ltd., Ottawa, ON (Canada)

    2003-07-01

    Most building envelope assemblies in Canada must include a vapour barrier in order to comply with Canadian building codes. The installation of sheet polyethylene between the studs and the interior sheathing has been the most common method because it provides more diffusion resistance than necessary to control condensation within a building envelope assembly. It has been suggested that the presence of a polyethylene vapour barrier on the warm-in-winter side of the insulation may actually cause moisture problems because a very low permeance material increases average moisture levels. This paper examined the theory that a vapour barrier at this location restricts drying of moisture that enters the building from outside. Pacific coastal regions of Canada and the United States were presented as examples. Other ways that a polyethylene vapour barrier affects wall performance were also presented. The advanced hygrothermal model HygIRC, developed by Canada's National Research Council, was used to simulate the performance of a wall assembly. Results indicate that eliminating the low permeance polyethylene vapour barrier does not necessarily reduce the risk of moisture problems. Removal of the vapour barrier may have some negative effects, such as increased risk of periodic moisture accumulation and mold growth on paper-faced gypsum board. 7 refs., 2 tabs., 7 figs.

  12. New Regenerative Cycle for Vapor Compression Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Mark J. Bergander

    2005-08-29

    second step of compression. In the proposed system, the compressor compresses the vapor only to 50-60% of the final pressure, while the additional compression is provided by a jet device using internal potential energy of the working fluid flow. Therefore, the amount of mechanical energy required by a compressor is significantly reduced, resulting in the increase of efficiency (either COP or EER). The novelty of the cycle is in the equipment and in the way the multi-staging is accomplished. The anticipated result will be a new refrigeration system that requires less energy to accomplish a cooling task. The application of this technology will be for more efficient designs of: (1) Industrial chillers, (2) Refrigeration plants, (3) Heat pumps, (4) Gas Liquefaction plants, (5) Cryogenic systems.

  13. Characterisation of silicon carbide films deposited by plasma-enhanced chemical vapour deposition

    International Nuclear Information System (INIS)

    Iliescu, Ciprian; Chen Bangtao; Wei Jiashen; Pang, A.J.

    2008-01-01

    The paper presents a characterisation of amorphous silicon carbide films deposited in plasma-enhanced chemical vapour deposition (PECVD) reactors for MEMS applications. The main parameter was optimised in order to achieve a low stress and high deposition rate. We noticed that the high frequency mode (13.56 MHz) gives a low stress value which can be tuned from tensile to compressive by selecting the correct power. The low frequency mode (380 kHz) generates high compressive stress (around 500 MPa) due to ion bombardment and, as a result, densification of the layer achieved. Temperature can decrease the compressive value of the stress (due to annealing effect). A low etching rate of the amorphous silicon carbide layer was noticed for wet etching in KOH 30% at 80 o C (around 13 A/min) while in HF 49% the layer is practically inert. A very slow etching rate of amorphous silicon carbide layer in XeF 2 -7 A/min- was observed. The paper presents an example of this application: PECVD-amorphous silicon carbide cantilevers fabricated using surface micromachining by dry-released technique in XeF 2

  14. Distribution and excretion of inhaled mercury vapour

    Energy Technology Data Exchange (ETDEWEB)

    Gage, J C

    1961-01-01

    Rats have been exposed for varying periods to an atmosphere containing 1 mg/cu.m. mercury vapor. The toxic effects produced showed resemblances to signs of mercurialism in man. An attempt has been made to study the kinetics of absorption and excretion of mercury from measurements of the amounts excreted and stored in the tissues. The efficiency of absorption of mercury by the rat lung is about 50%. A small proportion is excreted into the gut. After about 10 days of continuous exposure a steady state is reached in which excretion balances absorption. During short exposures the turnover of mercury in all tissues except brain is fairly rapid and most of the mercury is cleared from the body within a week after exposure. The urinary excretion of mercury, during the initial stage of storage in the tissues and the final stage of clearance, shows divergencies from the simple exponential pattern; there appears to be a delay mechanism in the kidney which, in intermittent exposures, may result in the occurrence of peak excretion during periods of non-exposure. After more prolonged exposures the mercury in the kidney appears to be converted to a form which is only very slowly excreted. The significance of the urinary excretion of mercury by man after industrial exposure to mercury vapour is discussed. The rat experiments suggest that single measurements will give only limited information concerning industrial conditions, but that an approximate assessment of the total absorbed during a working week would be obtained if it were possible to make a seven-day collection of urine. Repeated measurements after exposure would yield information on the duration of exposure and would have some diagnostic value.

  15. Thermal analysis and modeling of a swimming pool heating system by utilizing waste energy rejected from a chiller unit of an ice rink

    OpenAIRE

    Kuyumcu Muhammed Enes; Yumrutaş Recep

    2017-01-01

    This study deals with the thermal analysis and modeling of a swimming pool heating system in which the waste energy rejected from the chiller unit of an ice rink is used as an energy source. The system consists of a swimming pool and an ice rink coupled by a chiller unit. The swimming pool and the ice rink both indoor types and were constructed in city of Gaziantep, Turkey. The thermal energy requirement for each section is determined by thermal analysis of each component of the system. Effec...

  16. Retrieving mesospheric water vapour from observations of volume scattering radiances

    Directory of Open Access Journals (Sweden)

    P. Vergados

    2009-02-01

    Full Text Available This study examines the possibility for a theoretical approach in the estimation of water vapour mixing ratios in the vicinity of polar mesospheric clouds (PMC using satellite observations of Volume Scattering Radiances (VSR obtained at the wavelength of 553 nm. The PMC scattering properties perturb the underlying molecular Rayleigh scattered solar radiance of the background atmosphere. As a result, the presence of PMC leads to an enhancement in the observed VSR at the altitude of the layer; the PMC VSRs are superimposed on the exponentially decreasing with height Rayleigh VSR, of the PMC-free atmosphere. The ratio between the observed and the Rayleigh VSR of the background atmosphere is used to simulate the environment in which the cloud layer is formed. In addition, a microphysical model of ice particle formation is employed to predict the PMC VSRs. The initial water vapour profile is perturbed until the modelled VSRs match the observed, at which point the corresponding temperature and water vapour profiles can be considered as a first approximation of those describing the atmosphere at the time of the observations. The role of temperature and water vapour in the cloud formation is examined by a number of sensitivity tests suggesting that the water vapour plays a dominant role in the cloud formation in agreement with experimental results. The estimated water vapour profiles are compared with independent observations to examine the model capability in the context of this study. The results obtained are in a good agreement at the peak of the PMC layer although the radiance rapidly decreases with height below the peak. This simplified scenario indicates that the technique employed can give a first approximation estimate of the water vapour mixing ratio, giving rise to the VSR observed in the presence of PMC.

  17. Exergy and Exergoenvironmental Analysis of a CCHP System Based on a Parallel Flow Double-Effect Absorption Chiller

    Directory of Open Access Journals (Sweden)

    Ali Mousafarash

    2016-01-01

    Full Text Available A combined cooling, heating, and power (CCHP system which produces electricity, heating, and cooling is modeled and analyzed. This system is comprised of a gas turbine, a heat recovery steam generator, and a double-effect absorption chiller. Exergy analysis is conducted to address the magnitude and the location of irreversibilities. In order to enhance understanding, a comprehensive parametric study is performed to see the effect of some major design parameters on the system performance. These design parameters are compressor pressure ratio, gas turbine inlet temperature, gas turbine isentropic efficiency, compressor isentropic efficiency, and temperature of absorption chiller generator inlet. The results show that exergy efficiency of the CCHP system is higher than the power generation system and the cogeneration system. In addition, the results indicate that when waste heat is utilized in the heat recovery steam generator, the greenhouse gasses are reduced when the fixed power output is generated. According to the parametric study results, an increase in compressor pressure ratio shows that the network output first increases and then decreases. Furthermore, an increase in gas turbine inlet temperature increases the system exergy efficiency, decreasing the total exergy destruction rate consequently.

  18. On the pressure drop in Plate Heat Exchangers used as desorbers in absorption chillers

    International Nuclear Information System (INIS)

    Garcia-Hernando, N.; Almendros-Ibanez, J.A.; Ruiz, G.; Vega, M. de

    2011-01-01

    The influence of the pressure drop in Plate Heat Exchangers (PHE) in the boiling temperature of LiBr-H 2 O and NH 3 -H 2 O solutions is studied. For the NH 3 -H 2 O solution, the pressure drop-temperature saturation relationship estates that high pressure drops can be allowed in the solution with negligible changes in the saturation temperature, and in the PHE performance. Besides, in the case of the LiBr-H 2 O solution, as the working pressure is usually very low, the analysis of the pressure drop must be taken as a main limiting parameter for the use of Plate Heat Exchangers as vapour generators. In this case, the pressure drop may considerably change the boiling temperature of the solution entering the heat exchanger and therefore a higher heating fluid temperature may be required. A guideline to design these systems is proposed.

  19. On the pressure drop in Plate Heat Exchangers used as desorbers in absorption chillers

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Hernando, N.; de Vega, M. [Energy System Engineering (ISE), Departamento de Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, Avda. Universidad, 30, 28911 Leganes, Madrid (Spain); Almendros-Ibanez, J.A. [Escuela de Ingenieros Industriales de Albacete, Departamento de Mecanica Aplicada e Ingenieria de Proyectos, Universidad de Castilla La Mancha, Campus Universitario s/n, 02071 Albacete (Spain); Renewable Energy Research Institute, c/de la Investigacion s/n, 02071 Albacete (Spain); Ruiz, G. [Energy Efficiency and Renewables Department, Tecnicas Reunidas S.A., C/Arapiles No. 13, 10a, 28015 Madrid (Spain)

    2011-02-15

    The influence of the pressure drop in Plate Heat Exchangers (PHE) in the boiling temperature of LiBr-H{sub 2}O and NH{sub 3}-H{sub 2}O solutions is studied. For the NH{sub 3}-H{sub 2}O solution, the pressure drop-temperature saturation relationship estates that high pressure drops can be allowed in the solution with negligible changes in the saturation temperature, and in the PHE performance. Besides, in the case of the LiBr-H{sub 2}O solution, as the working pressure is usually very low, the analysis of the pressure drop must be taken as a main limiting parameter for the use of Plate Heat Exchangers as vapour generators. In this case, the pressure drop may considerably change the boiling temperature of the solution entering the heat exchanger and therefore a higher heating fluid temperature may be required. A guideline to design these systems is proposed. (author)

  20. Appropriate heat load ratio of generator for different types of air cooled lithium bromide–water double effect absorption chiller

    International Nuclear Information System (INIS)

    Li, Zeyu; Liu, Jinping

    2015-01-01

    Highlights: • Effect of heat load ratio of generator on the performance was analyzed. • The performance is sensitive to heat load ratio of generator. • The appropriate heat load ratio of generator for four systems was obtained. • The change of appropriate heat load ratio of generator for four systems was studied. - Abstract: The lower coefficient of performance and higher risk of crystallization in the higher surrounding temperature is the primary disadvantage of air cooled lithium bromide–water double effect absorption chiller. Since the coefficient of performance and risk of crystallization strongly depend on the heat load ratio of generator, the appropriate heat load ratio of generator can improve the performance as the surrounding temperature is higher. The paper mainly deals with the appropriate heat load ratio of generator of air cooled lithium bromide–water double effect absorption chiller. Four type systems named series, pre-parallel, rear parallel and reverse parallel flow configuration were considered. The corresponding parametric model was developed to analyze the comprehensive effect of heat load ratio of generator on the coefficient of performance and risk of crystallization. It was found that the coefficient of performance goes up linearly with the decrease of heat load ratio of generator. Simultaneously, the risk of crystallization also rises slowly at first but increases fast finally. Consequently, the appropriate heat load ratio of generator for the series and pre-parallel flow type systems is suggested to be 0.02 greater than the minimum heat load ratio of generator and that for the rear parallel and reverse parallel flow chillers should be 0.01 higher than the minimum heat load ratio of generator. Besides, the changes of minimum heat load ratio of generator for different type systems with the working condition were analyzed and compared. It was found that the minimum heat load ratio of generator goes up with the increase of

  1. GPS Tomography: Water Vapour Monitoring for Germany

    Science.gov (United States)

    Bender, Michael; Dick, Galina; Wickert, Jens; Raabe, Armin

    2010-05-01

    Ground based GPS atmosphere sounding provides numerous atmospheric quantities with a high temporal resolution for all weather conditions. The spatial resolution of the GPS observations is mainly given by the number of GNSS satellites and GPS ground stations. The latter could considerably be increased in the last few years leading to more reliable and better resolved GPS products. New techniques such as the GPS water vapour tomography gain increased significance as data from large and dense GPS networks become available. The GPS tomography has the potential to provide spatially resolved fields of different quantities operationally, i. e. the humidity or wet refractivity as required for meteorological applications or the refraction index which is important for several space based observations or for precise positioning. The number of German GPS stations operationally processed by the GFZ in Potsdam was recently enlarged to more than 300. About 28000 IWV observations and more than 1.4 millions of slant total delay data are now available per day with a temporal resolution of 15 min and 2.5 min, respectively. The extended network leads not only to a higher spatial resolution of the tomographically reconstructed 3D fields but also to a much higher stability of the inversion process and with that to an increased quality of the results. Under these improved conditions the GPS tomography can operate continuously over several days or weeks without applying too tight constraints. Time series of tomographically reconstructed humidity fields will be shown and different initialisation strategies will be discussed: Initialisation with a simple exponential profile, with a 3D humidity field extrapolated from synoptic observations and with the result of the preceeding reconstruction. The results are compared to tomographic reconstructions initialised with COSMO-DE analyses and to the corresponding model fields. The inversion can be further stabilised by making use of independent

  2. Vapour pressure isotope effects in liquid hydrogen chloride

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, J.N.C.; Calado, J.C.G. (Instituto Superior Tecnico, Lisbon (Portugal)); Jancso, Gabor (Hungarian Academy of Sciences, Budapest (Hungary). Central Research Inst. for Physics)

    1992-08-10

    The difference between the vapour pressures of HCl and DCl has been measured over the temperature range 170-203 K by a differential manometric technique in a precision cryostat. In this range the vapour pressure of HCl is higher than that of DCl by 3.2% at 170 K, decreasing to 0.9% at 200 K. The reduced partition function ratios f[sub l]/f[sub g] derived from the vapour pressure data can be described by the equation ln(f[sub l]/f[sub g]) = (3914.57[+-]10)/T[sup 2] - (17.730[+-]0.055)/T. The experimentally observed H-D vapour pressure isotope effect, together with the values on the [sup 35]Cl-[sup 37]Cl isotope effect available in the literature, is interpreted in the light of the statistical theory of isotope effects in condensed systems by using spectroscopic data of the vapour and liquid phases. The results indicate that the rotation in liquid hydrogen chloride is hindered. Temperature-dependent force constants for the hindered translational and rotational motions were invoked in order to obtain better agreement between the model calculation and experiment. (author).

  3. Ethanol vapour induced dilated cardiomyopathy in chick embryos

    International Nuclear Information System (INIS)

    Kamran, K.; Khan, M.Y.; Minhas, L.A.

    2013-01-01

    Objective: To study the effects of ethanol vapour inhalation on the heart chambers of chick embryo. Methods: The case-control study was conducted at the College of Physicians and Surgeons Pakistan regional centre in Islamabad from January to October 2007. Both experimental and control groups were divided into three sub-groups each, based on the day of the sacrifice. Each group was dissected on day 7, day 10 and day 22 or hatching whichever was earlier. The experimental sub-groups sacrificed on day 7, day 10 and on hatching, were exposed to ethanol vapours till day 6, 9 and 9 of incubation respectively. The diameter of all 4 chambers was measured in experimental hearts and compared with age-matched controls. SPSS 10 was used for statistical analysis. Results: Ethanol vapour exposure caused widening of all heart chambers in the experimental chick embryos sacrificed on day 7 and day 10 compared to the controls. The chambers of newly hatched chick hearts showed dilatation in all the chambers except the left ventricle. Conclusion: Ethanol vapour exposure during development affects the heart, resulting in the widening of all heart chambers. The exposure is as dangerous as drinking alcohol. Alcohol vapour exposure during development leads to progressive dilatation in different heart chambers, producing dilated cardiomyopathy. (author)

  4. Atomic origins of water-vapour-promoted alloy oxidation.

    Science.gov (United States)

    Luo, Langli; Su, Mao; Yan, Pengfei; Zou, Lianfeng; Schreiber, Daniel K; Baer, Donald R; Zhu, Zihua; Zhou, Guangwen; Wang, Yanting; Bruemmer, Stephen M; Xu, Zhijie; Wang, Chongmin

    2018-05-07

    The presence of water vapour, intentional or unavoidable, is crucial to many materials applications, such as in steam generators, turbine engines, fuel cells, catalysts and corrosion 1-4 . Phenomenologically, water vapour has been noted to accelerate oxidation of metals and alloys 5,6 . However, the atomistic mechanisms behind such oxidation remain elusive. Through direct in situ atomic-scale transmission electron microscopy observations and density functional theory calculations, we reveal that water-vapour-enhanced oxidation of a nickel-chromium alloy is associated with proton-dissolution-promoted formation, migration, and clustering of both cation and anion vacancies. Protons derived from water dissociation can occupy interstitial positions in the oxide lattice, consequently lowering vacancy formation energy and decreasing the diffusion barrier of both cations and anions, which leads to enhanced oxidation in moist environments at elevated temperatures. This work provides insights into water-vapour-enhanced alloy oxidation and has significant implications in other material and chemical processes involving water vapour, such as corrosion, heterogeneous catalysis and ionic conduction.

  5. Study of a vapor-compression air-conditioning system for jetliners

    Energy Technology Data Exchange (ETDEWEB)

    Roeyttae, P.

    2009-07-01

    Most modern passenger aeroplanes use air cycle cooling. A high-speed air cycle is a reliable and light option, but not very efficient. This thesis presents research work done to design a novel vapour cooling cycle for aeroplanes. Due to advancements in high-speed permanent magnet motors, the vapour cycle is seen as a competitive option for the air cycle in aeroplanes. The aerospace industry placews tighter demands on the weight, reliability and environmental effects of the machinery than those met by conventional chillers, and thus modifications to conventional design are needed. The thesis is divided into four parts: the initial screening of the working fluid, 1-D design and performance values of the compressor, 1-D off-design value predictions of the compressor and the 3-D design of the compressor. The R24fa was selected as the working fluid based the study. The off-design range of the compressor was predicted to be wide and suitable for the application. The air-conditioning system developed is considerably smaller than previous designs using centrifugal compressors. (orig.)

  6. Performance Evaluation of a Continuous Operation Adsorption Chiller Powered by Solar Energy Using Silica Gel and Water as the Working Pair

    Directory of Open Access Journals (Sweden)

    Hassan Zohair Hassan

    2014-10-01

    Full Text Available In the present study, dynamic analysis and performance evaluation of a solar-powered continuous operation adsorption chiller are introduced. The adsorption chiller uses silica gel and water as the working pair. The developed mathematical model represents the heat and mass transfer within the reactor coupled with the energy balance of the collector plate and the glass cover. Moreover, a non-equilibrium adsorption kinetic model is taken into account by using the linear driving force equation. The variation of solar radiation, wind speed, and atmospheric temperature along a complete cycle are considered for a more realistic simulation. Based on the case studied  and the baseline parameters, the chiller is found to acquire a coefficient of performance of 0.402. The average thermal efficiency of the solar collector is estimated to be 62.96% and the average total efficiency  approaches a value of 50.91%. Other performance parameters obtained are 363.8 W and 1.82 W/kg for the cooling capacity and the specific cooling power of the chiller, respectively. Furthermore, every 1 kg of silica gel inside the adsorption reactor produces a daily chilled water mass of 3 kg at a temperature of 10 ◦C. In addition, the cooling system harnesses 25.35% of the total available solar radiation and converts it to a cooling effect.

  7. Electron collision cross section sets of TMS and TEOS vapours

    Science.gov (United States)

    Kawaguchi, S.; Takahashi, K.; Satoh, K.; Itoh, H.

    2017-05-01

    Reliable and detailed sets of electron collision cross sections for tetramethylsilane [TMS, Si(CH3)4] and tetraethoxysilane [TEOS, Si(OC2H5)4] vapours are proposed. The cross section sets of TMS and TEOS vapours include 16 and 20 kinds of partial ionization cross sections, respectively. Electron transport coefficients, such as electron drift velocity, ionization coefficient, and longitudinal diffusion coefficient, in those vapours are calculated by Monte Carlo simulations using the proposed cross section sets, and the validity of the sets is confirmed by comparing the calculated values of those transport coefficients with measured data. Furthermore, the calculated values of the ionization coefficient in TEOS/O2 mixtures are compared with measured data to confirm the validity of the proposed cross section set.

  8. Technical and Economic Working Domains of Industrial Heat Pumps: Part 1 - Vapour Compression Heat Pumps

    DEFF Research Database (Denmark)

    Ommen, Torben Schmidt; Jensen, Jonas Kjær; Markussen, Wiebke Brix

    2014-01-01

    A large amount of operational and economic constraints limit the applicability of heat pumps operated with natural working fluids. The limitations are highly dependent on the integration of heat source and sink streams. An evaluation of feasible operating conditions is carried out considering...... the constraints of available refrigeration equipment and a requirement of a positive Net Present Value of the investment. The considered sink outlet temperature range is from 40 °C to 140 °C, but for the heat pumps considered in this paper, the upper limit is 100 °C. Five heat pumps are studied. For each set...... of heat sink and source temperatures the optimal solution is determined. At low sink temperature glide R717 heat pumps show best performance, while at higher sink glide transcritical R744 may become important. In a second paper, the results of the VCHP are compared to a similar study considering...

  9. ENERGY SAVING BY USING HOT GAS DEFROST IN VAPOUR COMPRESSION SYSTEM

    OpenAIRE

    D. D. Dixit, Dr.R.R.Arakerimath

    2017-01-01

    Efficient energy and its conservation is a great challenge for engineers. All the refrigeration and air conditioning machines consume large amount of electrical energy. To minimize its consumption various technologies are working day and night. As far as government of India is concern, it already started special norms which are standardized by BEE (Bureau of Energy Efficiency). Energy Standards are becoming more stringent and to meet up with them it is necessary to make refrigerators more ene...

  10. Fault diagnosis and refrigerant leak detection in vapour compression refrigeration systems

    Energy Technology Data Exchange (ETDEWEB)

    Tassou, S.A.; Grace, I.N. [Brunel University, Uxbridge (United Kingdom). Department of Mechanical Engineering

    2005-08-01

    The environmental impact of refrigeration systems can be reduced by operation at higher efficiency and reduction of refrigerant leakage. Refrigerant loss contributes both directly and indirectly to global warming through inefficient system operation, increased power consumption and greenhouse gas emissions and higher maintenance costs. Existing sensor-based leak detection methods are limited by the inability to detect gradual leakage and the need for careful sensor location. There is a requirement for a real-time performance monitoring approach to leak detection and fault diagnosis which overcomes these disadvantages. This paper reports on the development of a fault diagnosis and refrigerant leak detection system based on artificial intelligence and real-time performance monitoring. The system has been used successfully to distinguish between faulty and fault free operation, steady-state and transient operation, leakage and over charge conditions. Work currently underway is aimed at testing additional fault conditions and establishing further rules to distinguish between these patterns. (author)

  11. Intercomparison of TCCON and MUSICA Water Vapour Products

    Science.gov (United States)

    Weaver, D.; Strong, K.; Deutscher, N. M.; Schneider, M.; Blumenstock, T.; Robinson, J.; Notholt, J.; Sherlock, V.; Griffith, D. W. T.; Barthlott, S.; García, O. E.; Smale, D.; Palm, M.; Jones, N. B.; Hase, F.; Kivi, R.; Ramos, Y. G.; Yoshimura, K.; Sepúlveda, E.; Gómez-Peláez, Á. J.; Gisi, M.; Kohlhepp, R.; Warneke, T.; Dohe, S.; Wiegele, A.; Christner, E.; Lejeune, B.; Demoulin, P.

    2014-12-01

    We present an intercomparison between the water vapour products from the Total Carbon Column Observing Network (TCCON) and the MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water (MUSICA), two datasets from ground-based Fourier Transform InfraRed (FTIR) spectrometers with good global representation. Where possible, comparisons to radiosondes are also included. The near-infrared TCCON measurements are optimized to provide precise monitoring of greenhouse gases for carbon cycle studies; however, TCCON's retrievals also produce water vapour products. The mid-infrared MUSICA products result from retrievals optimized to give precise and accurate information about H2O, HDO, and δD. The MUSICA water vapour products have been validated by extensive intercomparisons with H2O and δD in-situ measurements made from ground, radiosonde, and aircraft (Schneider et al. 2012, 2014), as well as by intercomparisons with satellite-based H2O and δD remote sensing measurements (Wiegele et al., 2014). This dataset provides a valuable reference point for other measurements of water vapour. This study is motivated by the limited intercomparisons performed for TCCON water vapour products and limited characterisation of their uncertainties. We compare MUSICA and TCCON products to assess the potential for TCCON measurements to contribute to studies of the water cycle, water vapour's role in climate and use as a tracer for atmospheric dynamics, and to evaluate the performance of climate models. The TCCON and MUSICA products result from measurements taken using the same FTIR instruments, enabling a comparison with constant instrumentation. The retrieval techniques differ, however, in their method and a priori information. We assess the impact of these differences and characterize the comparability of the TCCON and MUSICA datasets.

  12. DNABIT Compress – Genome compression algorithm

    OpenAIRE

    Rajarajeswari, Pothuraju; Apparao, Allam

    2011-01-01

    Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, “DNABIT Compress” for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our ...

  13. Diffusion and flow of water vapours in chromatographic Alumina gel

    International Nuclear Information System (INIS)

    Khan, M.; Shah, H. U.

    2005-01-01

    The kinetics of sorption of water vapours in chromatographic alumina gel was studied. Water vapours are adsorbed on the gel at temperature (15 degree C) at different constant relative pressure from 0.1-0.93 p/p. Rate constant, Effective diffusivities, Knudsen diffusivities and bulk diffusivities were determined through Fick type equation. Total pore volume is 0.498 cc g-1 and specific surface area comes to be 465 m2 g-1 as obtained by Gurvitsch rule and Kieselve's quantities respectively. An average pore radius (hydraulic) is 1.1x10/sub -7/ cm. The study of these quantities provide a strong basis for evaluating surface properties. (author)

  14. Spontaneuos and Parametric Processes in Warm Rubidium Vapours

    Directory of Open Access Journals (Sweden)

    Dąbrowski M.

    2014-12-01

    Full Text Available Warm rubidium vapours are known to be a versatile medium for a variety of experiments in atomic physics and quantum optics. Here we present experimental results on producing the frequency converted light for quantum applications based on spontaneous and stimulated processes in rubidium vapours. In particular, we study the efficiency of spontaneously initiated stimulated Raman scattering in the Λ-level configuration and conditions of generating the coherent blue light assisted by multi-photon transitions in the diamond-level configuration. Our results will be helpful in search for new types of interfaces between light and atomic quantum memories.

  15. Variation and design criterion of heat load ratio of generator for air cooled lithium bromide–water double effect absorption chiller

    International Nuclear Information System (INIS)

    Li, Zeyu; Liu, Liming; Liu, Jinping

    2016-01-01

    Highlights: • Design criterion of heat load ratio of generator is vital to system performance. • Heat load ratio of generator changes with working condition. • Change of heat load ratio of generator for four systems was obtained and compared. • Design criterion of heat load ratio of generator was presented. - Abstract: The heat load ratio of generator (HLRG) is a special system parameter because it is not fixed at the design value but changes with the working condition. For the air cooled chiller, the deviation from the design working condition occurs easily due to the variation of the surrounding temperature. The system is likely to suffer from crystallization when the working condition is different from the designed one if the HLRG is designed improperly. Consequently, the design criterion of HLRG based on a broad range of working condition is essential and urgent to the development of air cooled lithium bromide–water double effect absorption chiller. This paper mainly deals with the variation of HLRG with the working condition as well as corresponding design criterion. Four types of double effect chillers named series, pre-parallel, rear parallel and reverse parallel flow system were considered. The parametric model was developed by the introduction of a new thermodynamic relationship of generator. The change of HLRG for different types of chillers with the working condition was analyzed and compared. The corresponding design criterion of HLRG was presented. This paper is helpful for further improvement of the performance and reliability of air cooled lithium bromide–water double effect absorption chiller.

  16. Energy and exergy analysis of multi-effects distillation with thermo vapour compressor (MED-TVC) desalination system

    Energy Technology Data Exchange (ETDEWEB)

    Saffari, A.; Sayyaadi, H. [Khaje Nasir Toosi Univ. of Technology, Tehran (Iran, Islamic Republic of). Faculty of Mechanical Engineering, Energy Division; Alishiri, M. [Fan Niroo Co., Tehran (Iran, Islamic Republic of). Desalination and Water Solutions

    2008-07-01

    Countries around the world have a significant need for high-quality water. The desalination industry is especially important in ensuring the supply of high-quality water, especially the countries around the Persian Gulf such as Iran. A multiple-effect distiller (MED) with thermal vapor compression (TVC) system is more attractive than other thermal systems due to its effectiveness, easier operation and maintenance, and good economics. This paper presented a heat and mass balance relation and comprehensive exergy analysis of a typical MED with a thermal vapour compression desalination system. The purpose of the study was to provide a cost-effective tool that could be applied in the design, development and optimization of thermal desalination plants. The paper discussed the energy simulation, with particular reference to the temperatures for each effect; the condenser, gain output ratio, distillate production rate, brine outlet and feed water rates for each effect; steam consumption; coolant sea water and total sea water inlet rate; pressure distribution in the evaporators; and the entertained vapour rate at TVC. Exergy analysis revealed that the steam ejector and evaporators are the main sources of exergy destruction. It was also shown that lowering the temperature difference can minimize exergy losses. 21 refs., 4 tabs., 16 figs.

  17. DNABIT Compress – Genome compression algorithm

    Science.gov (United States)

    Rajarajeswari, Pothuraju; Apparao, Allam

    2011-01-01

    Data compression is concerned with how information is organized in data. Efficient storage means removal of redundancy from the data being stored in the DNA molecule. Data compression algorithms remove redundancy and are used to understand biologically important molecules. We present a compression algorithm, “DNABIT Compress” for DNA sequences based on a novel algorithm of assigning binary bits for smaller segments of DNA bases to compress both repetitive and non repetitive DNA sequence. Our proposed algorithm achieves the best compression ratio for DNA sequences for larger genome. Significantly better compression results show that “DNABIT Compress” algorithm is the best among the remaining compression algorithms. While achieving the best compression ratios for DNA sequences (Genomes),our new DNABIT Compress algorithm significantly improves the running time of all previous DNA compression programs. Assigning binary bits (Unique BIT CODE) for (Exact Repeats, Reverse Repeats) fragments of DNA sequence is also a unique concept introduced in this algorithm for the first time in DNA compression. This proposed new algorithm could achieve the best compression ratio as much as 1.58 bits/bases where the existing best methods could not achieve a ratio less than 1.72 bits/bases. PMID:21383923

  18. Design and analysis of a waste gasification energy system with solid oxide fuel cells and absorption chillers

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2018-01-01

    Energy saving is an open point in most European countries where energy policies are oriented to reduce the use of fossil fuels, greenhouses emissions and energy independence, and to increase the use of renewable energies. In the last several years, new technologies have been developed and some...... of them received subsidies to increase installation and reduce cost. This article presents a new sustainable trigeneration system (power, heat and cool) based on a solid oxide fuel cell (SOFC) system integrated with an absorption chiller for special applications such as hotels, resorts, hospitals, etc....... with a focus on plant design and performance. The proposal system is based on the idea of gasifying the municipal waste, producing syngas serving as fuel for the trigeneration system. Such advanced system when improved is thus self-sustainable without dependency on net grid, district heating and district...

  19. Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions

    International Nuclear Information System (INIS)

    Gong Jianying; Gao Tieyu; Yuan Xiuling; Huang Dong

    2008-01-01

    The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically

  20. Development of the Hybrid Operation Method of a Multi-Geothermal Heat Pump System and Absorption Chiller-Heater

    Directory of Open Access Journals (Sweden)

    Young-Ju Jung

    2015-08-01

    Full Text Available Considerable efforts have been made to reduce the energy consumption of buildings due to the energy crisis, and, the Korean government has supported the use of renewable energy through various grants. Among the possible renewable energy sources, geothermal energy can be used regardless of the outside weather. Therefore, energy consumption can be reduced considerably in summer and winter. Despite the increasing use of renewable energy, the use of renewables has not been operating appropriately. Therefore, this study examined some of the problems of the operation of renewable energy and some possible improvements. The aim of the study is to evaluate a building containing an actual installed multi-geothermal heat pump (Multi-GHP system, in terms of the energy efficiency. In addition, this study evaluated the present control system and the method of complex operation regarding existing heat sources systems and GHP systems through a simulation. The results can be regarded as the result of a hybrid operation method for the improvement of an existing operation. Therefore, the Multi-GHP system energy use of a hybrid operation condition of the Multi-GHP systems and the absorption (ABS chiller-heater system was reduced compared to the operation condition of the Multi-GHP system, and the total energy consumption of the heat source equipment was reduced. The proposed operation plan was evaluated after applying the system to a building. These results showed that the efficient operation of a Multi-GHP hybrid operation method is possible. As a result, the GHP energy use of Multi-GHP systems and the ABS chiller-heater system was reduced by 30% compared to existing operation and the total energy consumption of heat source equipment was reduced by 78%.

  1. Vapour-liquid equilibria of the hard core Yukawa fluid

    NARCIS (Netherlands)

    Smit, B.; Frenkel, D.

    1991-01-01

    Techniques which extend the range of applicability of the Gibbs ensemble technique for particles which interact with a hard core potential are described. The power of the new technique is demonstrated in a numerical study of the vapour-liquid coexistence curve of the hard core Yukawa fluid.

  2. No sodium in the vapour plumes of Enceladus.

    Science.gov (United States)

    Schneider, Nicholas M; Burger, Matthew H; Schaller, Emily L; Brown, Michael E; Johnson, Robert E; Kargel, Jeffrey S; Dougherty, Michele K; Achilleos, Nicholas A

    2009-06-25

    The discovery of water vapour and ice particles erupting from Saturn's moon Enceladus fuelled speculation that an internal ocean was the source. Alternatively, the source might be ice warmed, melted or crushed by tectonic motions. Sodium chloride (that is, salt) is expected to be present in a long-lived ocean in contact with a rocky core. Here we report a ground-based spectroscopic search for atomic sodium near Enceladus that places an upper limit on the mixing ratio in the vapour plumes orders of magnitude below the expected ocean salinity. The low sodium content of escaping vapour, together with the small fraction of salt-bearing particles, argues against a situation in which a near-surface geyser is fuelled by a salty ocean through cracks in the crust. The lack of observable sodium in the vapour is consistent with a wide variety of alternative eruption sources, including a deep ocean, a freshwater reservoir, or ice. The existing data may be insufficient to distinguish between these hypotheses.

  3. Measurement of copper vapour laser-induced deformation of ...

    Indian Academy of Sciences (India)

    2014-02-14

    Feb 14, 2014 ... Laser & Plasma Technology Division, Beam Technology Development Group,. Bhabha Atomic ... of dielectric-coated mirror, caused by an incident repetitive pulsed laser beam with high average power. Minimum ... the optical surface deformation, caused by irradiation by a copper vapour laser (CVL) beam.

  4. Making ET AAS Determination Less Dependent on Vapourization ...

    African Journals Online (AJOL)

    NICO

    The quantification of the analytes in ET AAS is normally attained by the measurement and integration of transient absorbance. High degree of atomization and constant vapour transportation rate for the analyte atoms in the absorption volume are considered to be crucial to grant correctness of the measurements. However ...

  5. Detection of quadrupole relaxation in an optically pumped cesium vapour

    Energy Technology Data Exchange (ETDEWEB)

    Bernabeu, E; Tornos, J

    1985-10-01

    The relaxation of quadrupole orientation induced by means of optical pumping in a cesium vapour is experimentally studied, and the results are compared to the theoretical predictions. The optical detection process of this type of orientation is also discussed as a function of the polarization and spectral profile of the detection light.

  6. Characterisation and optical vapour sensing properties of PMMA thin films

    Energy Technology Data Exchange (ETDEWEB)

    Capan, I. [Balikesir University, Science and Arts Faculty, Physics Department, 10100 Balikesir (Turkey)], E-mail: inci.capan@gmail.com; Tarimci, C. [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan, Ankara (Turkey); Hassan, A.K. [Sheffield Hallam University, Materials and Engineering Research Institute, City Campus, Pond Street, Sheffield S1 1WB (United Kingdom); Tanrisever, T. [Balikesir University, Science and Arts Faculty, Chemistry Department, 10100 Balikesir (Turkey)

    2009-01-01

    The present article reports on the characterisation of spin coated thin films of poly (methyl methacrylate) (PMMA) for their use in organic vapour sensing application. Thin film properties of PMMA are studied by UV-visible spectroscopy, atomic force microscopy and surface plasmon resonance (SPR) technique. Results obtained show that homogeneous thin films with thickness in the range between 6 and 15 nm have been successfully prepared when films were spun at speeds between 1000-5000 rpm. Using SPR technique, the sensing properties of the spun films were studied on exposures to several halohydrocarbons including chloroform, dichloromethane and trichloroethylene. Data from measured kinetic response have been used to evaluate the sensitivity of the studied films to the various analyte molecules in terms of normalised response (%) per unit concentration (ppm). The highest PMMA film sensitivity of 0.067 normalised response per ppm was observed for chloroform vapour, for films spun at 1000 rpm. The high film's sensitivity to chloroform vapour was ascribed mainly to its solubility parameter and molar volume values. Effect of film thickness on the vapour sensing properties is also discussed.

  7. Microscopic characterisation of suspended graphene grown by chemical vapour deposition

    NARCIS (Netherlands)

    Bignardi, L.; Dorp, W.F. van; Gottardi, S.; Ivashenko, O.; Dudin, P.; Barinov, A.; de Hosson, J.T.M.; Stöhr, M.; Rudolf, P.

    2013-01-01

    We present a multi-technique characterisation of graphene grown by chemical vapour deposition (CVD) and thereafter transferred to and suspended on a grid for transmission electron microscopy (TEM). The properties of the electronic band structure are investigated by angle-resolved photoelectron

  8. Human volunteer study with PGME: Eye irritation during vapour exposure

    NARCIS (Netherlands)

    Emmen, H.H.; Muijser, H.; Arts, J.H.E.; Prinsen, M.K.

    2003-01-01

    The objective of this study was to establish the possible occurrence of eye irritation and subjective symptoms in human volunteers exposed to propylene glycol monomethyl ether (PGME) vapour at concentrations of 0, 100 and 150 ppm. Testing was conducted in 12 healthy male volunteers using a repeated

  9. Turkish Undergraduates' Misconceptions of Evaporation, Evaporation Rate, and Vapour Pressure

    Science.gov (United States)

    Canpolat, Nurtac

    2006-01-01

    This study focused on students' misconceptions related to evaporation, evaporation rate, and vapour pressure. Open-ended diagnostic questions were used with 107 undergraduates in the Primary Science Teacher Training Department in a state university in Turkey. In addition, 14 students from that sample were interviewed to clarify their written…

  10. Water vapour and carbon dioxide decrease nitric oxide readings

    NARCIS (Netherlands)

    vanderMark, TW; Kort, E; Meijer, RJ; Postma, DS; Koeter, GH

    Measurement of nitric oxide levels in exhaled ah-is commonly performed using a chemiluminescence detector. However, water vapour and carbon dioxide affect the chemiluminescence process, The influence of these gases at the concentrations present in exhaled air has not vet been studied. For this in

  11. Vapour intrusion from the vadose zone—seven algorithms compared

    NARCIS (Netherlands)

    Provoost, J.; Bosman, A.; Reijnders, L.; Bronders, J.; Touchant, K.; Swartjes, F.

    2010-01-01

    Background, aim and scope: Vapours of volatile organic compounds (VOCs) emanating from contaminated soils may move through the unsaturated zone to the subsurface. VOC in the subsurface can be transported to the indoor air by convective air movement through openings in the foundation and basement.

  12. Erratum to: Measurement of copper vapour laser-induced ...

    Indian Academy of Sciences (India)

    Erratum to: Measurement of copper vapour laser-induced deformation of dielectric-coated mirror surface by. Michelson interferometer. A WAHID. ∗. , S KUNDU, J S B SINGH, A K SINGH, A KHATTAR,. S K MAURYA, J S DHUMAL and K DASGUPTA. Laser & Plasma Technology Division, Beam Technology Development ...

  13. Impact of major volcanic eruptions on stratospheric water vapour

    Directory of Open Access Journals (Sweden)

    M. Löffler

    2016-05-01

    Full Text Available Volcanic eruptions can have a significant impact on the Earth's weather and climate system. Besides the subsequent tropospheric changes, the stratosphere is also influenced by large eruptions. Here changes in stratospheric water vapour after the two major volcanic eruptions of El Chichón in Mexico in 1982 and Mount Pinatubo on the Philippines in 1991 are investigated with chemistry–climate model simulations. This study is based on two simulations with specified dynamics of the European Centre for Medium-Range Weather Forecasts Hamburg – Modular Earth Submodel System (ECHAM/MESSy Atmospheric Chemistry (EMAC model, performed within the Earth System Chemistry integrated Modelling (ESCiMo project, of which only one includes the long-wave volcanic forcing through prescribed aerosol optical properties. The results show a significant increase in stratospheric water vapour induced by the eruptions, resulting from increased heating rates and the subsequent changes in stratospheric and tropopause temperatures in the tropics. The tropical vertical advection and the South Asian summer monsoon are identified as sources for the additional water vapour in the stratosphere. Additionally, volcanic influences on tropospheric water vapour and El Niño–Southern Oscillation (ENSO are evident, if the long-wave forcing is strong enough. Our results are corroborated by additional sensitivity simulations of the Mount Pinatubo period with reduced nudging and reduced volcanic aerosol extinction.

  14. Contribution to the liquid-vapour equilibrium of potassium and sodium mixtures

    International Nuclear Information System (INIS)

    Schreinlechner, I.; Schwarz, N.

    1975-10-01

    In this paper the phase diagram of the binary system potassium-sodium in the liquid-vapour range was calculated for different pressures and temperatures, assuming the two metals acting as ideal solution. The assumption was verified by experimental results. It is thus possible to calculate the separation factor for the rectification of potassium and to estimate the content of sodium in the vapour phase during experiments with vapourized potassium from the data of the vapour pressures of the pure metals. (author)

  15. Effect of paint on vapour resistivity in plaster

    Directory of Open Access Journals (Sweden)

    de Villanueva, L.

    2008-12-01

    Full Text Available The vapour resistivity of plaster coatings such as paint and their effectiveness as water repellents were studied in several types of plaster. To this end, painted, unpainted and pigmented specimens were tested. Experimental values were collected on diffusion and vapour permeability, or its inverse, water vapour resistivity.The data obtained were very useful for evaluating moisture exchange between plaster and the surrounding air, both during initial drying and throughout the life of the material. They likewise served as a basis for ensuring the proper evacuation of water vapour in walls, and use of the capacity of the porous network in plaster products to regulate moisture content or serve as a water vapour barrier to avoid condensation.Briefly, the research showed that pigments, water-based paints and silicon-based water repellents scantly raised vapour resistance. Plastic paints, enamels and lacquers, however, respectively induced five-, ten- and twenty-fold increases in vapour resistivity, on average.Se estudia el fenómeno de la resistividad al vapor de los de yeso y el efecto impermeabilizante que producen los recubrimientos de pintura sobre diversos tipos de yeso y escayola. Para ello, se ensayan probetas desnudas y recubiertas con distintos tipos de pintura, así como coloreados en masa. Se obtienen valores experimentales de la difusividad o permeabilidad al vapor o su inverso la resistividad al vapor de agua.Los datos obtenidos son muy útiles para valorar el fenómeno del intercambio de humedad entre el yeso y el ambiente, tanto durante el proceso de su secado inicial, como en el transcurso de su vida. Así como para disponer soluciones adecuadas para la evacuación del vapor de agua a través de los cerramientos, para utilizar la capacidad de regulación de la humedad, que proporciona el entramado poroso de los productos de yeso, o para impedir el paso del vapor de agua y evitar condensaciones.Como resumen de la investigación, se

  16. Discrete vapour cavity model with improved timing of opening and collapse of cavities

    NARCIS (Netherlands)

    Bergant, A.; Tijsseling, A.S.; Vítkovský, J.P.; Simpson, A.R.; Lambert, M.F.

    2007-01-01

    Transient vaporous cavitation occurs in hydraulic piping systems when the liquid pressure falls to the vapour pressure. Cavitation may occur as a localized vapour cavity (large void fraction) or as distributed vaporous cavitation (small void fraction). The discrete vapour cavity model (DVCM) with

  17. Antifungal Activity of Clove Essential Oil and its Volatile Vapour Against Dermatophytic Fungi

    OpenAIRE

    Chee, Hee Youn; Lee, Min Hee

    2007-01-01

    Antifungal activities of clove essential oil and its volatile vapour against dermatophytic fungi including Candida albicans, Epidermophyton floccosum. Microsporum audouinii, Trichophyton mentagrophytes, and Trichophyton rubrum were investigated. Both clove essential oil and its volatile vapour strongly inhibit spore germination and mycelial growth of the dermatophytic fungi tested. The volatile vapour of clove essential oil showed fungistatic activity whereas direct application of clove essen...

  18. Ethanol vapour sensing properties of screen printed WO 3 thick films

    Indian Academy of Sciences (India)

    The ethanol vapour sensing properties of these thick films were investigated at different operating temperatures and ethanol vapour concentrations. The WO3 thick films exhibit excellent ethanol vapour sensing properties with a maximum sensitivity of ∼1424.6% at 400°C in air atmosphere with fast response and recovery ...

  19. The sun also can cold. In the summer, the adsorption chillers utilizes the capacity of solar thermal energy; Die Sonne kann auch kalt. Adsorptionskaeltemaschine lastet im Sommer die Solarthermie besser aus

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Andre [SorTec AG, Halle an der Saale (Germany)

    2013-06-15

    A combination of solar thermal systems with adsorption chillers from SorTech (Speyer, Federal Republic of Germany) enables an environmentally friendly and efficient recovery of coldness for the solar cooling of buildings by means of excess heat energy.

  20. A static analytical apparatus for vapour pressures and (vapour + liquid) phase equilibrium measurements with an internal stirrer and view windows

    International Nuclear Information System (INIS)

    Guo, Hao; Gong, Maoqiong; Dong, Xueqiang; Wu, Jianfeng

    2014-01-01

    Highlights: • A new static analytical apparatus for vapour pressures and VLE data was designed. • The {R600a + R245fa} system was selected as a verification system. • Correlation of VLE data was made using PRvdWs and PRHVNRTL model. • Good agreement can be found with the literature data. - Abstract: A new static analytical apparatus for reliable vapour pressures and (vapour + liquid) equilibrium data of small-scale cell (≈150 mL) with internal stirrer and view windows was designed. In this work, the compositions of the phases were analyzed by a gas chromatograph connected on-line with TCD detectors. The operating pressure ranges from (0 to 3000) kPa, and the operating temperature range from (293 to 400) K. Phase equilibrium data for previously reported systems were first measured to test the credibility of the newly developed apparatus. The test included vapour pressure of 1,1,1,3,3-pentafluoropropane (R245fa) and isobutane (R600a), VLE of the (R600a + R245fa) system from T = (293.150 to 343.880) K. The measured VLE data are regressed with thermodynamic models using Peng–Robinson EoS with two different models, viz. the van der Waals mixing rule, and the Huron–Vidal mixing rule utilising the non-random two-liquid activity coefficient model. Thermodynamic consistency testing is also performed for the newly measured experimental data

  1. CHEMICAL VAPOUR DEPOSITION FROM A RADIATION-SENSITIVE PRECURSOR

    DEFF Research Database (Denmark)

    2017-01-01

    The present invention relates in one aspect to a method of depositing a thin film on a substrate by chemical vapour deposition (CVD) from a radiation-sensitive precursor substance. The method comprises the steps of: (i) placing the substrate in a reaction chamber of a CVD system; (ii) heating...... heating pulse followed by an idle period; (iii) during at least one of the idle periods, providing a pressure pulse of precursor substance inside the reaction chamber by feeding at least one precursor substance to the reaction chamber so as to establish a reaction partial pressure for thin film deposition...... is formed. According to a further aspect, the invention relates to a chemical vapour deposition (CVD) system for depositing a thin film onto a substrate using precursor substances containing at least one radiation sensitive species....

  2. Dew-point measurements at high water vapour pressure

    Science.gov (United States)

    Lomperski, S.; Dreier, J.

    1996-05-01

    A dew-point meter capable of measuring humidity at high vapour pressure and high temperature has been constructed and tested. Humidity measurements in pure steam were made over the temperature range 100 - 1500957-0233/7/5/003/img1C and a vapour pressure range of 1 - 4 bar. The dew-point meter performance was assessed by comparing measurements with a pressure transmitter and agreement between the two was within 0957-0233/7/5/003/img2% relative humidity. Humidity measurements in steam - air mixtures were also made and the dew-point meter readings were compared to those of a zirconia oxygen sensor. For these tests the dew-point meter readings were generally within 0957-0233/7/5/003/img2% relative humidity of the oxygen sensor measurements.

  3. Study of vapour pressure of lithium nitrate solutions in ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Verevkin, Sergey [Abteilung Physikalische Chemie, Institut fuer Chemie, Universitaet Rostock, Hermannstrasse, 14, D-18055 Rostock (Germany); Safarov, Javid [Heat and Refrigeration Techniques, Azerbaijan Technical University, H. Javid Avn. 25, AZ1073 Baku (Azerbaijan)]. E-mail: javids@azdata.net; Bich, Eckard [Abteilung Physikalische Chemie, Institut fuer Chemie, Universitaet Rostock, Hermannstrasse, 14, D-18055 Rostock (Germany); Hassel, Egon [Lehrstuhl fuer Technische Thermodynamik, Fakultaet Maschinenbau und Schiffstechnik, Universitaet Rostock, Albert-Einstein-Str. 2, D-18059 Rostock (Germany); Heintz, Andreas [Abteilung Physikalische Chemie, Institut fuer Chemie, Universitaet Rostock, Hermannstrasse, 14, D-18055 Rostock (Germany)

    2006-05-15

    Vapour pressure p of (LiNO{sub 3} + C{sub 2}H{sub 5}OH) solutions at T = (298.15 to 323.15) K were measured, osmotic, activity coefficients ({phi}, {gamma}) and activity of solvent a {sub s} have been evaluated. The experiments were carried out in the molality range m = (0.19125 to 2.21552) mol . kg{sup -1}. The Antoine equation was used for the empirical description of the experimental vapour pressure results and the (Pitzer + Mayorga) model with inclusion of Archer's ionic strength dependence of the third virial coefficient for the calculated osmotic coefficients were used. The parameters of the Archer for the extended Pitzer model was used for the evaluation of activity coefficients.

  4. Calculation of vapour pressures over mixed carbide fuels

    International Nuclear Information System (INIS)

    Joseph, M.; Mathews, C.K.

    1988-01-01

    Vapour pressure over the uranium-plutonium mixed carbide (Usub(l-p) Pusub(p C) was calculated in the temperature range of 1300-9000 for various compositions (p=0.1 to 0.7). Effects of variation of the sesquicarbide content were also studied. The principle of corresponding states was applied to UC and mixed carbides to obtain the equation of state. (author)

  5. Relaxation of quadrupole orientation in an optically pumped alkali vapour

    Energy Technology Data Exchange (ETDEWEB)

    Bernabeu, E; Tornos, J

    1985-04-01

    The relaxation of quadrupole orientation (alignment) in an optically pumped alkali vapour is theoretically studied by taking into account the relaxation processes by alkali-buffer gas, alkali-alkali with spin exchange and alkali-cell wall (diffusion process) collisions. The relaxation transients of the quadrupole orientation are obtained by introducing a first-order weak-pumping approximation (intermediate pumping) less restrictive than the usually considered (zeroth order) one.

  6. Steam/water separation device for drying a wet vapour

    International Nuclear Information System (INIS)

    Sundheimer, P.

    1986-01-01

    The aim of the present invention is to dry a wet vapour which flows up to the device. The device has at least a group of steam dryer elements in a zone in which there is a vertical apertured panel; this vertical apertured panel is a metal grille with baffles the inlet steam flow to make it horizontal or slightly inclined to the bottom. The invention applies more particularly, to PWR steam generators [fr

  7. Chemical vapour deposition of thin-film dielectrics

    International Nuclear Information System (INIS)

    Vasilev, Vladislav Yu; Repinsky, Sergei M

    2005-01-01

    Data on the chemical vapour deposition of thin-film dielectrics based on silicon nitride, silicon oxynitride and silicon dioxide and on phosphorus- and boron-containing silicate glasses are generalised. The equipment and layer deposition procedures are described. Attention is focussed on the analysis and discussion of the deposition kinetics and on the kinetic models for film growth. The film growth processes are characterised and data on the key physicochemical properties of thin-film covalent dielectric materials are given.

  8. Modelling of vapour explosion in a stratified geometry

    International Nuclear Information System (INIS)

    Brayer, Claude

    1994-01-01

    A vapour explosion is the explosive vaporisation of a volatile liquid in contact with another hotter liquid. Such a violent vaporisation requires an intimate mixing and a fine fragmentation of both liquids. Based on a synthesis of published experimental results, the author of this research thesis reports the development of a new physical model which describes the explosion. In this model, the explosion propagation is due to the propagation of the pressure wave associated with this this explosion, all along the vapour film which initially separates both liquids. The author takes the presence of water in the liquid initially located over the film into account. This presence of vapour explains experimental propagation rates. Another consequence, when the pressure wave passes, is an acceleration of liquids at different rates below and above the film. The author considers that a mixture layer then forms from the point of disappearance of the film, between both liquids, and that fragmentation is due to the turbulence in this mixture layer. This fragmentation model is then introduced into an Euler thermodynamic, three-dimensional and multi-constituents code of calculation, MC3D, to study the influence of fragmentation on thermal exchanges between the various constituents on the volatile liquid vaporisation [fr

  9. The vapour pressure of americium(III) chloride

    International Nuclear Information System (INIS)

    Schuster, W.

    1983-01-01

    Based on the method described by Fischer, an ultramicro-size appratus was developed for static determination of the saturation vapour pressure of highly radioactive materials. The apparatus was tested with MgCl 2 , MnCl 2 , HoCl 3 and ScF 3 . The vapour pressure curves of MgCl 2 and MnCl 2 were in good agreement with other publications and thus proved the efficiency of the apparatus in spite of its difficulties of handling. The values measured for HoCl 3 and ScF 3 differed from those of earlier publications. However, these deviations have been observed before and may be the result of the different measuring principles of static and dynamic methods. For AmCl 3 , the following vapour pressure equation was established: log psub(Torr)=-(11826/T)+10.7. The thermodynamic parameters of the evaporation process were calculated on this basis, and the values for AmBr 3 and PnCl 3 were determined by extrapolation. (orig.) [de

  10. Surface polish of PLA parts in FDM using dichloromethane vapour

    Directory of Open Access Journals (Sweden)

    Jin Yifan

    2017-01-01

    Full Text Available Fused deposition modelling has become one of the most diffused rapid prototyping techniques, which is widely used to fabricate prototypes. However, further application of this technology is severely limited by poor surface roughness. Thus it is necessary to adopt some operations to improve surface quality. Chemical finishing is typically employed to finish parts in fused deposition modelling (FDM. The purpose of this paper is to decrease the surface roughness for polylactic acid (PLA parts in FDM. The chemical reaction mechanism during the treating process is analysed. Then NaOH solution and dichloromethane vapour are used to treat FDM specimens respectively. A 3D laser microscope has been applied to assess the effects in terms of surface topography and roughness. The experimental results show that treatment using dichloromethane vapour performs much better than NaOH solution. Compared with the untreated group, surface roughness obtained through vapour treatment decreases by 88 per cent. This research has been conducted to provide a better method to treat PLA parts using chemical reagents.

  11. A Compressive Superresolution Display

    KAUST Repository

    Heide, Felix; Gregson, James; Wetzstein, Gordon; Raskar, Ramesh; Heidrich, Wolfgang

    2014-01-01

    In this paper, we introduce a new compressive display architecture for superresolution image presentation that exploits co-design of the optical device configuration and compressive computation. Our display allows for superresolution, HDR, or glasses-free 3D presentation.

  12. A Compressive Superresolution Display

    KAUST Repository

    Heide, Felix

    2014-06-22

    In this paper, we introduce a new compressive display architecture for superresolution image presentation that exploits co-design of the optical device configuration and compressive computation. Our display allows for superresolution, HDR, or glasses-free 3D presentation.

  13. Microbunching and RF Compression

    International Nuclear Information System (INIS)

    Venturini, M.; Migliorati, M.; Ronsivalle, C.; Ferrario, M.; Vaccarezza, C.

    2010-01-01

    Velocity bunching (or RF compression) represents a promising technique complementary to magnetic compression to achieve the high peak current required in the linac drivers for FELs. Here we report on recent progress aimed at characterizing the RF compression from the point of view of the microbunching instability. We emphasize the development of a linear theory for the gain function of the instability and its validation against macroparticle simulations that represents a useful tool in the evaluation of the compression schemes for FEL sources.

  14. Mining compressing sequential problems

    NARCIS (Netherlands)

    Hoang, T.L.; Mörchen, F.; Fradkin, D.; Calders, T.G.K.

    2012-01-01

    Compression based pattern mining has been successfully applied to many data mining tasks. We propose an approach based on the minimum description length principle to extract sequential patterns that compress a database of sequences well. We show that mining compressing patterns is NP-Hard and

  15. Demonstration of an on-site PAFC cogeneration system with waste heat utilization by a new gas absorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Urata, Tatsuo [Tokyo Gas Company, LTD, Tokyo (Japan)

    1996-12-31

    Analysis and cost reduction of fuel cells is being promoted to achieve commercial on-site phosphoric acid fuel cells (on-site FC). However, for such cells to be effectively utilized, a cogeneration system designed to use the heat generated must be developed at low cost. Room heating and hot-water supply are the most simple and efficient uses of the waste heat of fuel cells. However, due to the short room-heating period of about 4 months in most areas in Japan, the sites having demand for waste heat of fuel cells throughout the year will be limited to hotels and hospitals Tokyo Gas has therefore been developing an on-site FC and the technology to utilize tile waste heat of fuel cells for room cooling by means of an absorption refrigerator. The paper describes the results of fuel cell cogeneration tests conducted on a double effect gas absorption chiller heater with auxiliary waste heat recovery (WGAR) that Tokyo Gas developed in its Energy Technology Research Laboratory.

  16. Performance of LiCl Impregnated Mesoporous Material Coating over Corrugated Heat Exchangers in a Solid Sorption Chiller

    Directory of Open Access Journals (Sweden)

    Hongzhi Liu

    2018-06-01

    Full Text Available The composite material made by impregnating 40 wt. % lithium chloride (LiCl into the mesopores of a kind of natural porous rock (Wakkanai Siliceous Shale: WSS micropowders (short for “WSS + 40 wt. % LiCl” had been developed previously, and can be regenerated below 100 °C with a cooling coefficient of performance (COP of approximately 0.3 when adopted as a sorbent in a sorption cooler. In this study, experiments have been carried out on an intermittent solid sorption chiller with the WSS + 40 wt. % LiCl coating over two aluminum corrugated heat exchangers. Based on the experimental condition (regeneration temperature of 80 °C, condensation temperature of 30 °C in the desorption process; sorption temperature of 30 °C and evaporation temperature of 12 °C in the sorption process, the water sorption amount changes from 20 wt. % to 70 wt. % in one sorption cooling cycle. Moreover, a specific cooling power (SCP of 86 W/kg, a volumetric specific cooling power (VSCP of 42 W/dm3, and a specific sorption power of 170 W/kg can be achieved with a total sorption and desorption time of 20 min. The obtained cooling COP is approximately 0.16.

  17. Steady state simulation of a double-effect steam absorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.S.A.M.S.; Gilani, S.I.U.H. [Universiti Teknologi Petronas, Tronoh, Perak (Malaysia). Dept. of Mechanical Engineering

    2011-07-01

    Absorption cooling systems have become increasingly popular in recent years from the viewpoint of energy and environment. Despite a lower coefficient of performance (COP) as compared to the vapor compression, absorption refrigeration systems are attractive for using inexpensive waste heat, solar, geothermal or biomass energy sources for which the cost of supply is negligible in many cases. In addition absorption refrigeration uses natural substances which do not contribute towards ozone depletion and global warming. Owing to the serious environmental problems and the price of the traditional energy resources, the use of industrial waste heat or renewable energy as the driving force for vapor absorption cooling systems is continuously increasing. A steady-state model is developed to predict the performance of an absorption refrigeration system using LiBr-water as working pair. Each component of the cycle is modelled based on mass and energy balances. The design point parameters are determined. The refrigeration effect, coefficient of performance and load factor are analyzed for different heat input. Simulation is carried out and the results are compared with actual data and showed good agreement.

  18. Compression for radiological images

    Science.gov (United States)

    Wilson, Dennis L.

    1992-07-01

    The viewing of radiological images has peculiarities that must be taken into account in the design of a compression technique. The images may be manipulated on a workstation to change the contrast, to change the center of the brightness levels that are viewed, and even to invert the images. Because of the possible consequences of losing information in a medical application, bit preserving compression is used for the images used for diagnosis. However, for archiving the images may be compressed to 10 of their original size. A compression technique based on the Discrete Cosine Transform (DCT) takes the viewing factors into account by compressing the changes in the local brightness levels. The compression technique is a variation of the CCITT JPEG compression that suppresses the blocking of the DCT except in areas of very high contrast.

  19. Radiological Image Compression

    Science.gov (United States)

    Lo, Shih-Chung Benedict

    The movement toward digital images in radiology presents the problem of how to conveniently and economically store, retrieve, and transmit the volume of digital images. Basic research into image data compression is necessary in order to move from a film-based department to an efficient digital -based department. Digital data compression technology consists of two types of compression technique: error-free and irreversible. Error -free image compression is desired; however, present techniques can only achieve compression ratio of from 1.5:1 to 3:1, depending upon the image characteristics. Irreversible image compression can achieve a much higher compression ratio; however, the image reconstructed from the compressed data shows some difference from the original image. This dissertation studies both error-free and irreversible image compression techniques. In particular, some modified error-free techniques have been tested and the recommended strategies for various radiological images are discussed. A full-frame bit-allocation irreversible compression technique has been derived. A total of 76 images which include CT head and body, and radiographs digitized to 2048 x 2048, 1024 x 1024, and 512 x 512 have been used to test this algorithm. The normalized mean -square-error (NMSE) on the difference image, defined as the difference between the original and the reconstructed image from a given compression ratio, is used as a global measurement on the quality of the reconstructed image. The NMSE's of total of 380 reconstructed and 380 difference images are measured and the results tabulated. Three complex compression methods are also suggested to compress images with special characteristics. Finally, various parameters which would effect the quality of the reconstructed images are discussed. A proposed hardware compression module is given in the last chapter.

  20. Factors affecting release of ethanol vapour in active modified atmosphere packaging systems for horticultural products

    Directory of Open Access Journals (Sweden)

    Weerawate Utto

    2014-04-01

    Full Text Available The active modified atmosphere packaging (active MAP system , which provides interactive postharvest control , using ethanol vapour controlled release, is one of the current interests in the development of active packaging for horticultural products. A number of published research work have discussed the relationship between the effectiveness of ethanol vapour and its concentration in the package headspace, including its effect on postharvest decay and physiological controls. This is of importance because a controlled release system should release and maintain ethanol vapour at effective concentrations during the desired storage period. A balance among the mass transfer processes of ethanol vapour in the package results in ethanol vapour accumulation in the package headspace. Key factors affecting these processes include ethanol loading, packaging material, packaged product and storage environment (temperature and relative h umidity. This article reviews their influences and discusses future work required to better understand their influences on ethanol vapour release and accumulations in active MAP.

  1. Comparison of interaction mechanisms of copper phthalocyanine and nickel phthalocyanine thin films with chemical vapours

    Science.gov (United States)

    Ridhi, R.; Singh, Sukhdeep; Saini, G. S. S.; Tripathi, S. K.

    2018-04-01

    The present study deals with comparing interaction mechanisms of copper phthalocyanine and nickel phthalocyanine with versatile chemical vapours: reducing, stable aromatic and oxidizing vapours namely; diethylamine, benzene and bromine. The variation in electrical current of phthalocyanines with exposure of chemical vapours is used as the detection parameter for studying interaction behaviour. Nickel phthalocyanine is found to exhibit anomalous behaviour after exposure of reducing vapour diethylamine due to alteration in its spectroscopic transitions and magnetic states. The observed sensitivities of copper phthalocyanine and nickel phthalcyanine films are different in spite of their similar bond numbers, indicating significant role of central metal atom in interaction mechanism. The variations in electronic transition levels after vapours exposure, studied using UV-Visible spectroscopy confirmed our electrical sensing results. Bromine exposure leads to significant changes in vibrational bands of metal phthalocyanines as compared to other vapours.

  2. Experimental study of a thermochemical compressor for an absorption/compression hybrid cycle

    International Nuclear Information System (INIS)

    Ventas, R.; Vereda, C.; Lecuona, A.; Venegas, M.

    2012-01-01

    Highlights: ► Experimental study of a thermochemical compressor for absorption/compression cycle. ► Spray adiabatic absorber using NH 3 –LiNO 3 solution working fluid. ► It is able to operate between 57 and 110 °C varying concentration between 0.46 and 0.59. ► The increase of absorber pressure decreases the circulation ratio. ► The numerical model performed agrees with the experimental results. -- Abstract: An experimental study of a thermochemical compressor with ammonia–lithium nitrate solution as working fluid has been carried out. This compressor incorporates a single-pass adiabatic absorber and all the heat exchangers are of the plate type: absorber subcooler, generator and solution heat exchanger. The thermochemical compressor has been studied as part of a single-effect absorption chiller hybridized with an in-series low-pressure compression booster. The adiabatic absorber uses fog jet injectors. The generator hot water temperatures for the external driving flow are in the range of 57–110 °C and the absorber pressures range between 429 and 945 kPa. Experimental results are compared with a numerical model showing a high agreement. The performance of the thermochemical compressor, evaluated through the circulation ratio, improves for higher absorber pressures, indicating the potential of pressure boosting. For the same circulation ratio, the driving hot water inlet temperature decreases with the rise of the absorber pressure. The thermochemical compressor, based on an adiabatic absorber, can produce refrigerant with very low driving temperatures, between 57 and 70 °C, what is interesting for solar cooling applications and very low temperature residual heat recovery. Efficiencies and cooling power are offered when this hybrid thermochemical compressor is implemented in a chiller, showing the effect of different operating parameters.

  3. Vapour phase motion in cryogenic systems containing superheated and subcooled liquids

    Science.gov (United States)

    Kirichenko, Yu. A.; Chernyakov, P. S.; Seregin, V. E.

    The development of vent pipelines, and venting storage tanks for cryogenic liquids requires the knowledge of the law of motion as well as regularities of vapour content variation in the liquid and heat dissipation by the vapour phase. This is a theoretical study of the effect of superheating (subcooling) of the liquid, relative acceleration and reduced pressure upon the size and velocity of noninteracting vapour bubbles, moving in the liquid, and upon their resistance and heat transfer coefficients.

  4. Antifungal activity of clove essential oil and its volatile vapour against dermatophytic fungi.

    Science.gov (United States)

    Chee, Hee Youn; Lee, Min Hee

    2007-12-01

    Antifungal activities of clove essential oil and its volatile vapour against dermatophytic fungi including Candida albicans, Epidermophyton floccosum. Microsporum audouinii, Trichophyton mentagrophytes, and Trichophyton rubrum were investigated. Both clove essential oil and its volatile vapour strongly inhibit spore germination and mycelial growth of the dermatophytic fungi tested. The volatile vapour of clove essential oil showed fungistatic activity whereas direct application of clove essential oil showed fungicidal activity.

  5. (Vapour + liquid) equilibria for (2,2-dimethoxypropane + methanol) and (2,2-dimethoxypropane + acetone)

    International Nuclear Information System (INIS)

    Jiang Hui; Li Haoran; Wang Congmin; Tan Taijun; Han Shijun

    2003-01-01

    The isothermal and isobaric (vapour + liquid) equilibria for (2,2-dimethoxypropane + methanol) and (2,2-dimethoxypropane + acetone) measured with an inclined ebulliometer are presented. The experimental results are analysed using the UNIQUAC equation with the temperature-dependent binary parameters with satisfactory results. Isobaric (vapour + liquid) equilibria data for these systems at p=99.99 kPa are compared with the literature data. Experimental vapour pressure of 2,2-dimethoxypropane are also included

  6. Silicon nanowire arrays as learning chemical vapour classifiers

    International Nuclear Information System (INIS)

    Niskanen, A O; Colli, A; White, R; Li, H W; Spigone, E; Kivioja, J M

    2011-01-01

    Nanowire field-effect transistors are a promising class of devices for various sensing applications. Apart from detecting individual chemical or biological analytes, it is especially interesting to use multiple selective sensors to look at their collective response in order to perform classification into predetermined categories. We show that non-functionalised silicon nanowire arrays can be used to robustly classify different chemical vapours using simple statistical machine learning methods. We were able to distinguish between acetone, ethanol and water with 100% accuracy while methanol, ethanol and 2-propanol were classified with 96% accuracy in ambient conditions.

  7. Low pressure chemical vapour deposition of temperature resistant colour filters

    International Nuclear Information System (INIS)

    Verheijen, J.; Bongaerts, P.; Verspui, G.

    1987-01-01

    The possibility to deposit multilayer colour filters, based on optical inference, by means of Low Pressure Chemical Vapour Deposition (LPCVD) was investigated. The filters were made in a standard LPCVD system by alternate deposition of Si/sub 3/N/sub 4/ and SiO/sub 2/ layers. This resulted in filters with excellent colour uniformity on glass and quartz substrates. No difference was measured between theoretically calculated transmission and the transmission of the filters deposited by LPCVD. Temperature treatment at 600 0 C in air air showed no deterioration of filter quality and optical properties

  8. Consistent vapour-liquid equilibrium data containing lipids

    DEFF Research Database (Denmark)

    Cunico, Larissa; Ceriani, Roberta; Sarup, Bent

    Consistent physical and thermodynamic properties of pure components and their mixtures are important for process design, simulation, and optimization as well as design of chemical based products. In the case of lipids, it was observed a lack of experimental data for pure compounds and also...... for their mixtures in open literature, what makes necessary the development of reliable predictive models based on limited data. To contribute to the missing data, measurements of isobaric vapour-liquid equilibrium (VLE) data of three binary mixtures at two different pressures were performed at State University...

  9. The Seasonal Cycle of Water Vapour on Mars from Assimilation of Thermal Emission Spectrometer Data

    Science.gov (United States)

    Steele, Liam J.; Lewis, Stephen R.; Patel, Manish R.; Montmessin, Franck; Forget, Francois; Smith, Michael D.

    2014-01-01

    We present for the first time an assimilation of Thermal Emission Spectrometer (TES) water vapour column data into a Mars global climate model (MGCM). We discuss the seasonal cycle of water vapour, the processes responsible for the observed water vapour distribution, and the cross-hemispheric water transport. The assimilation scheme is shown to be robust in producing consistent reanalyses, and the global water vapour column error is reduced to around 2-4 pr micron depending on season. Wave activity is shown to play an important role in the water vapour distribution, with topographically steered flows around the Hellas and Argyre basins acting to increase transport in these regions in all seasons. At high northern latitudes, zonal wavenumber 1 and 2 stationary waves during northern summer are responsible for spreading the sublimed water vapour away from the pole. Transport by the zonal wavenumber 2 waves occurs primarily to the west of Tharsis and Arabia Terra and, combined with the effects of western boundary currents, this leads to peak water vapour column abundances here as observed by numerous spacecraft. A net transport of water to the northern hemisphere over the course of one Mars year is calculated, primarily because of the large northwards flux of water vapour which occurs during the local dust storm around L(sub S) = 240-260deg. Finally, outlying frost deposits that surround the north polar cap are shown to be important in creating the peak water vapour column abundances observed during northern summer.

  10. Calculation of vapour bubble growth on the lower generatrix of horizontal tubes

    International Nuclear Information System (INIS)

    Chajka, V.D.

    1987-01-01

    The known models of vapour bubble growth are compared with experimental data. Cinematographic study of vapour formation during water boiling was carried out with elements of horizontal tubes of copper 10, 16, 24, 34 and 70 mm in diameter under the pressure of 100 kPa and specific thermal loadings of 20 and 40 kW/m 2 . According to the experimental data the main volume of vapour phase is occupied by vapour bubbles from the lower part of the horizontal tube. Five stages of vapour bubble growth on the lower generatrix of the horizontal tube: nucleation, growth to the point of breaking off from nucleate centre, the breaking off from the nucleate centre, the tube surface flowing around during floating up, the breaking off from the tube surface, were singled out. The shape of vapour volume varied during the whole period of the bubble growth and it was mainly determined by the horizontal tube diameter. The change of vapour bubble radius in time is the function of the horizontal tube diameter. Comparison of the experimental data with the known models of vapour bubble growth has shown, that every stage of vapour bubble growth on the lower generatrix of the tube is determined by the complex of thermal and hydrodynamic conditions, the effect of which depends on the horizontal tube diameter

  11. Steam direct re compression and energy recovery in ethanol-water distillation; Recompressao direta de vapor e recuperacao de energia na destilacao do sistema etanol-agua

    Energy Technology Data Exchange (ETDEWEB)

    Ravagnani, T M.K.; Pereira, J A.F.R. [Universidade Estadual de Campinas, SP (Brazil). Dept. de Engenharia Quimica

    1985-12-31

    Steam re compression has been presented as the most promising and economical substitute for conventional distillation. The present work describes and analyze the application of the direct vapour re compression technique to ethanol-water distillation columns, when the azeotrope is the top product. Results shows that energy savings up to 80% can be obtained. The study takes in account the effects of the column operation conditions, addition of inert gas in the re compression circuit and compressor efficiency (assumed to be polytropic). Analysis of the results permits to obtain the optimum conditions for the use of the direct steam re compression in the ethanol-water distillation. (author). 5 figs., 7 refs

  12. A miniature discriminating monitor for tritiated water vapour

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, R.A.H.; Ravazzani, A.; Pacenti, P. [European Commission, JRC, Institute for Advanced Material, Ispra, Vatican City State, Holy See (Italy); Campi, F. [Nuclear Engineering Dept., Polytechnic of Milan (Italy)

    1998-07-01

    In detecting tritium in air (or other gas) for worker safety, it is important to discriminate between tritiated water vapour and elemental tritium, because the first is much more easily absorbed in the lungs. We haveinvented (patent pending) an innovative discriminating monitor which works better than existing designs, and is much smaller. The air (or other sample gas) passes over a large surface area of solid scintillator, which is surface-treated to make it hygroscopic. Tritiated water vapour in the air exchanges continuously, rapidly and reversibly with the water in the thin hygroscopic layer; which is of the order of 1 micron thick. The beta-emissions from tritium in the hygroscopic layer hit the solid scintillator, causing flashes of light that are detected by a photomultiplier. The new discriminating monitor for tritiated species in air offers superior performance to existing discriminating monitors, and is much smaller. It is planned to develop a portable version which could serve as a personal tritium monitor. (authors)

  13. Study of water vapour adsorption kinetics on aluminium oxide materials

    Science.gov (United States)

    Livanova, Alesya; Meshcheryakov, Evgeniy; Reshetnikov, Sergey; Kurzina, Irina

    2017-11-01

    Adsorbents on the basis of active aluminum oxide are still of demand on the adsorbent-driers market. Despite comprehensive research of alumina adsorbents, and currently is an urgent task to improve their various characteristics, and especially the task of increasing the sorption capacity. In the present work kinetics of the processes of water vapours' adsorption at room temperature on the surface of desiccant samples has been studied. It was obtained on the basis of bayerite and pseudoboehmite experimentally. The samples of pseudoboehmite modified with sodium and potassium ions were taken as study objects. The influence of an adsorbent's grain size on the kinetics of water vapours' adsorption was studied. The 0.125-0.25 mm and 0.5-1.0 mm fractions of this sample were used. It has been revealed that the saturation water vapor fine powder (0.125-0.25 mm) is almost twofold faster in comparison with the sample of fraction 0.5-1.0 mm due to the decrease in diffusion resistance in the pores of the samples when moving from the sample of larger fraction to the fine-dispersed sample. It has been established that the adsorption capacity of the pseudoboehmite samples, modified by alkaline ions, is higher by ˜40 %, than for the original samples on the basis of bayerite and pseudoboehmite.

  14. First Townsend coefficient of organic vapour in avalanche counters

    International Nuclear Information System (INIS)

    Sernicki, J.

    1990-01-01

    A new concept is presented in the paper for implementing the proven method of determining the first Townsend coefficient (α) of gases using an avalanche counter. The A and B gas constants, interrelated by the expression α/p=A exp[-B/(K/p)], are analyzed. Parallel-plate avalanche counters (PPAC) with an electrode spacing d from 0.1 to 0.4 cm have been employed for the investigation, arranged to register low-energy alpha particles at n-heptane vapour pressures of p≥5 Torr. An in-depth discussion is given, covering the veracity and the behaviour vs K/p, of the n-heptane A and B constants determined at reduced electric-field intensity values ranging from 173.5 to 940 V/cm Torr; the constants have been found to depend upon d. The results of the investigation are compared to available data of the α coefficient of organic vapours used in avalanche counters. The PPAC method of determining α reveals some imperfections at very low values of the pd product. (orig.)

  15. Pulmonary CT findings in acute mercury vapour exposure

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Manabu; Sato, Kimihiko; Heianna, Jyouiti; Hirano, Yoshinori; Omachi, Kohiti; Izumi, Jyunichi; Watarai, Jiro

    2001-01-01

    AIM: We describe the pulmonary computed tomography (CT) findings in acute mercury poisoning. MATERIALS AND METHODS: Initial (n= 8) and follow-up (n= 6) chest CT examinations in eight patients exposed to mercury vapour while cutting pipes in a sulphuric acid plant were reviewed. Of the eight patients, two were asymptomatic and had normal CT results, two were asymptomatic but had abnormalities on CT, and four had both acute symptoms and positive CT results. The patients were all men whose ages ranged from 37 to 54 years (mean, 49 years). RESULTS: Poorly defined nodules were present in five of six patients with positive CT findings, present alone in two patients or as part of a mixed pattern in three. They were random in distribution. Alveolar consolidation (n= 3) and areas of ground-glass opacity (n= 4) were observed and were more prominent in the most severely affected patients with the highest blood and urine level of mercury, predominantly in the upper and/or middle zone. These abnormal findings on CT resolved with (n= 1) or without (n= 5) steroid therapy. Pathological findings (n= 1) demonstrated acute interstitial changes predominantly with oedema. CONCLUSION: We report CT findings in eight patients acutely exposed to mercury vapour. The pulmonary injury was reversible on CT in these cases. Hashimoto, M. (2001)

  16. Thermally decarboxylated sodium bicarbonate: Interactions with water vapour, calorimetric study

    Directory of Open Access Journals (Sweden)

    Natalia Volkova

    2013-06-01

    Full Text Available Isothermal titration calorimetry (ITC was used to study interactions between water vapour and the surface of thermally converted sodium bicarbonate (NaHCO3. The decarboxylation degree of the samples was varied from 3% to 35% and the humidity range was 54–100%. The obtained enthalpy values were all exothermic and showed a positive linear correlation with decarboxylation degrees for each humidity studied. The critical humidity, 75% (RHo, was determined as the inflection point on a plot of the mean−ΔHkJ/mole Na2CO3 against RH. Humidities above the critical humidity lead to complete surface dissolution. The water uptake (m was determined after each calorimetric experiment, complementing the enthalpy data. A mechanism of water vapour interaction with decarboxylated samples, including the formation of trona and Wegscheider’s salt on the bicarbonate surface is proposed for humidities below RHo. Keywords: Isothermal titration calorimetry, Sodium bicarbonate, Sodium carbonate, Trona salt, Wegscheider’s salt, Enthalpy, Relative humidity, Pyrolytic decarboxylation

  17. The response of liquid-filled pipes to vapour collapse

    International Nuclear Information System (INIS)

    Tijsseling, A.S.; Fan, D.

    1991-01-01

    The collapse of vapour cavities in liquid is usually accompanied with almost instantaneous pressure rises. These pressure rises impose severe loads on liquid-conveying pipes whenever the cavities become sufficiently large. Due to the impact nature of loadings, movement of the pipe walls can be expected. Tests are performed in a water-filled closed pipe suspended by thin steel wires. Vaporous cavities are induced in the liquid by hitting the pipe axially by a steel rod. The volume of the cavities can be varied by changing the initial pressure of the water. The developing and collapsing of cavities in the liquid is inferred from pressure measurements. Strain gauges and a laser Doppler vibrometer are used to record the response of the pipe to these pressures. The test results are compared with predictions from a numerical model. The model describes 1) axial stress wave propagations in the pipe and 2) water hammer and cavitation phenomena in the liquid. Pipe and liquid interact via 1) the radial expansion and contraction of the pipe wall and 2) the closed ends of the pipe, where large vapour cavities may develop. (author)

  18. Improved grand canonical sampling of vapour-liquid transitions.

    Science.gov (United States)

    Wilding, Nigel B

    2016-10-19

    Simulation within the grand canonical ensemble is the method of choice for accurate studies of first order vapour-liquid phase transitions in model fluids. Such simulations typically employ sampling that is biased with respect to the overall number density in order to overcome the free energy barrier associated with mixed phase states. However, at low temperature and for large system size, this approach suffers a drastic slowing down in sampling efficiency. The culprits are geometrically induced transitions (stemming from the periodic boundary conditions) which involve changes in droplet shape from sphere to cylinder and cylinder to slab. Since the overall number density does not discriminate sufficiently between these shapes, it fails as an order parameter for biasing through the transitions. Here we report two approaches to ameliorating these difficulties. The first introduces a droplet shape based order parameter that generates a transition path from vapour to slab states for which spherical and cylindrical droplets are suppressed. The second simply biases with respect to the number density in a tetragonal subvolume of the system. Compared to the standard approach, both methods offer improved sampling, allowing estimates of coexistence parameters and vapor-liquid surface tension for larger system sizes and lower temperatures.

  19. Compressed sensing & sparse filtering

    CERN Document Server

    Carmi, Avishy Y; Godsill, Simon J

    2013-01-01

    This book is aimed at presenting concepts, methods and algorithms ableto cope with undersampled and limited data. One such trend that recently gained popularity and to some extent revolutionised signal processing is compressed sensing. Compressed sensing builds upon the observation that many signals in nature are nearly sparse (or compressible, as they are normally referred to) in some domain, and consequently they can be reconstructed to within high accuracy from far fewer observations than traditionally held to be necessary. Apart from compressed sensing this book contains other related app

  20. Sound speed of isobaric heat capacity in the saturated and superheated vapour of cesium, rubidium and potassium

    International Nuclear Information System (INIS)

    Novikov, I.I.; Roschupkin, V.V.

    1985-01-01

    The paper reviews the work carried out on the thermodynamic properties of alkali metal vapours. The most systematic investigations concern the sound velocity measurements for saturated and superheated vapours of caesium, for saturated vapour of rubidium, and for superheated vapour of potassium. The Joule-Thompson coefficient has been studied in caesium vapour, and the isobaric heat capacity of potassium vapour has also been examined. The experimental methods for all these experiments are described, and the data obtained are presented in tabular form. (U.K.)

  1. Enabling the Distributed Generation Market of High Temperature Fuel Cell and Absorption Chiller Systems to Support Critical and Commercial Loads

    Science.gov (United States)

    DiMola, Ashley M.

    Buildings account for over 18% of the world's anthropogenic Greenhouse Gas (GHG) emissions. As a result, a technology that can offset GHG emissions associated with buildings has the potential to save over 9 Giga-tons of GHG emissions per year. High temperature fuel cell and absorption chiller (HTFC/AC) technology offers a relatively low-carbon option for meeting cooling and electric loads for buildings while producing almost no criteria pollutants. GHG emissions in the state of California would decrease by 7.48 million metric tons per year if every commercial building in the State used HTFC/AC technology to meet its power and cooling requirements. In order to realize the benefits of HTFC/AC technology on a wide scale, the distributed generation market needs to be exposed to the technology and informed of its economic viability and real-world potential. This work characterizes the economics associated with HTFC/AC technology using select scenarios that are representative of realistic applications. The financial impacts of various input factors are evaluated and the HTFC/AC simulations are compared to the economics of traditional building utilities. It is shown that, in addition to the emissions reductions derived from the systems, HTFC/AC technology is financially preferable in all of the scenarios evaluated. This work also presents the design of a showcase environment, centered on a beta-test application, that presents (1) system operating data gathered using a custom data acquisition module, and (2) HTFC/AC technology in a clear and approachable manner in order to serve the target audience of market stakeholders.

  2. PARAMETRIC STUDY OF ENERGY, EXERGY AND THERMOECONOMIC ANALYSES ON VAPOR-COMPRESSION SYSTEM CASCADED WITH LIBR/WATER AND NH3/WATER ABSORBTION CASCADE REFRIGERATION CYCLE

    Directory of Open Access Journals (Sweden)

    ahmet selim dalkilic

    2017-03-01

    Full Text Available Energy savings on cooling systems can be performed by using novel refrigeration cycles. For this aim, vapour compression-vapour absorption cascade refrigeration systems can be considered as substitute to single-stage vapour compression refrigeration systems. Renewable energy sources of geothermal and solar heat, waste heat of processes have been used by these cycles to provide cooling and they also require less electrical energy than vapour compression cycles having alternative refrigerants. In this study, a vapour compression (VC and vapour absorption (VA cascade systems are analysed with the second law analysis for varied cooling capacities. While lithium bromide-water and NH3/H2O are the working fluids in VA part, various refrigerants are used in VC section. The refrigerants of R134a and R600a, R410A and R407C are tested as drop in alternatives for R12 and R22, respectively. The effects of alteration in cooling capacity, superheating and sub cooling in VC part, temperature in the generator and absorber, and degree of overlap in cascade condenser in VA part on the coefficient of system performance are studied. Validation of the results have been performed by the values given in the literature. Improvement in COP of VC, VA and cascade system are obtained separately. According to the analyses, cascade systems’ COP values increase with increasing the temperatures of generator and evaporator and they also increase with decreasing the condenser and absorber temperatures. Moreover, the generator has the highest exergy destruction rates, second and third one were the condenser and absorber, respectively. Electricity consumption and payback period are also determined considering the various parameters of the study.

  3. On-site study of HCFC-22 substitution for HFC non-azeotropic blends (R417A, R422D) on a water chiller of a centralized HVAC system

    Energy Technology Data Exchange (ETDEWEB)

    Torrella, E.; Larumbe, J.A. [Polytechnic University of Valencia, Dep. of Applied Thermodynamics, Camino de Vera 14, E-46022 Valencia (Spain); Cabello, R.; Sanchez, D.; Llopis, R. [Jaume I University, Dep. of Mechanical Engineering and Construction, Campus de Riu Sec s/n, E-12071 Castellon (Spain)

    2010-09-15

    The European Regulation no 2037/2000 has banned manufacturing HCFC refrigerants from January 1st 2010, although its use is allowed up to 2015 if the fluids come from a recycling process. This situation creates the need for developing new working fluids to replace the HCFC in the refrigeration plants now in operation. Among all the HCFCs the R22 is the most widely used in a wide range of applications, especially in air conditioning. This work presents an on-site experimental study of the R22 replacement by two possible substitutes, the HFC-417A and the HFC-422D, in a water chiller in which the energy performance was evaluated. This chiller is part of the centralized HVAC system of a lecture room building at the Jaume I University of Castellon, Spain. This communication compares and analyses main operation parameters of the chiller when operating with each refrigerant in real conditions. (author)

  4. Development of a high temperature solar powered water chiller. Volume 3. Phase I technical progress report, September 26, 1977--June 1, 1978

    Energy Technology Data Exchange (ETDEWEB)

    English, R. A.

    1978-06-01

    This section describes the conceptual design rationale and resulting design configuration as well as providing estimates of cost and performance. Because the development of the turbo-compressor design paralleled the development of the chiller system design, all of the cost and performance data are based on intermediate turbo-compressor performance data, as well as on unoptimized components. Optimized performance was computed at the very end of Phase I, and only a brief comparison is made to show the potential gains available. Updating of all the predicted performance data for the final conceptual design will await Phase II.

  5. Claims in vapour device (e-cigarette) regulation: A Narrative Policy Framework analysis.

    Science.gov (United States)

    O'Leary, Renée; Borland, Ron; Stockwell, Tim; MacDonald, Marjorie

    2017-06-01

    The electronic cigarette or e-cigarette (vapour device) is a consumer product undergoing rapid growth, and governments have been adopting regulations on the sale of the devices and their nicotine liquids. Competing claims about vapour devices have ignited a contentious debate in the public health community. What claims have been taken up in the state arena, and how have they possibly influenced regulatory outcomes? This study utilized Narrative Policy Framework to analyze the claims made about vapour devices in legislation recommendation reports from Queensland Australia, Canada, and the European Union, and the 2016 deeming rule legislation from the United States, and examined the claims and the regulatory outcomes in these jurisdictions. The vast majority of claims in the policy documents represented vapour devices as a threat: an unsafe product harming the health of vapour device users, a gateway product promoting youth tobacco uptake, and a quasi-tobacco product impeding tobacco control. The opportunity for vapour devices to promote cessation or reduce exposure to toxins was very rarely presented, and these positive claims were not discussed at all in two of the four documents studied. The dominant claims of vapour devices as a public health threat have supported regulations that have limited their potential as a harm reduction strategy. Future policy debates should evaluate the opportunities for vapour devices to decrease the health and social burdens of the tobacco epidemic. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Utility of DMSP-SSM/I for integrated water vapour over the Indian seas

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging Solutions)

    Recent algorithms for Special Sensor Microwave/Imager (DMSP-SSM/I) satellite data are used for estimating integrated water vapour over the Indian seas. Integrated water vapour obtained from these algorithms is compared with that derived from radiosonde observations at Minicoy and Port. Blair islands. Algorithm-3 of ...

  7. Operating experience of RAPSODIE and PHENIX relating to sodium aerosols and vapours

    Energy Technology Data Exchange (ETDEWEB)

    Delisle, J P; Reboul, M; Elie, X [DRNR/STRS - Centre de Cadarache, Saint-Paul-lez-Durance (France)

    1977-01-01

    The main difficulties resulting from sodium aerosols and vapours in the cover gas which have been encountered for 10 years in RAPSODIE and for 3 years in PHENIX are reviewed: condensation of sodium in annular spaces; plugging in primary gas pipes; plugging of filters and vapour traps. All those problems were easily overcome. (author)

  8. Anisotropic Concrete Compressive Strength

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2017-01-01

    When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...

  9. Experiments with automata compression

    NARCIS (Netherlands)

    Daciuk, J.; Yu, S; Daley, M; Eramian, M G

    2001-01-01

    Several compression methods of finite-state automata are presented and evaluated. Most compression methods used here are already described in the literature. However, their impact on the size of automata has not been described yet. We fill that gap, presenting results of experiments carried out on

  10. Vapour pressure of D2O - Ice at temperatures below 237 K

    International Nuclear Information System (INIS)

    Heras, J.M.; Asensio, M.C.; Estiu, G.; Viscido, L.

    1984-01-01

    Accurate measurements of heavy water ice vapour pressures between 193 and 253 K have been carried out and an equation based on thermodynamic data has been derived in order to calculate the D 2 O-ice vapour pressures between 173 and 273 K. The agreement between our calculated vapour pressures and the available experimental data including those in this paper, is very good. The comparison between the theoretical calculations of H 2 O-ice and D 2 O-ice vapour pressures confirms the experimental evidence that H 2 O-ice is more volatile than D 2 O-ice at all temperatures in agreement with the vapour isotopic effect theory (VPIE).(author)

  11. A sensor of alcohol vapours based on thin polyaniline base film and quartz crystal microbalance.

    Science.gov (United States)

    Ayad, Mohamad M; El-Hefnawey, Gad; Torad, Nagy L

    2009-08-30

    Thin films of polyaniline base, emeraldine base (EB), coating on the quartz crystal microbalance (QCM) electrode were used as a sensitive layer for the detection of a number of primary aliphatic alcohols such as ethanol, methanol, 2-propanol and 1-propanol vapours. The frequency shifts (Deltaf) of the QCM were increased due to the vapour adsorption into the EB film. Deltaf were found to be linearly correlated with the concentrations of alcohols vapour in part per million (ppm). The sensitivity of the sensor was found to be governed by the chemical structure of the alcohol. The sensor shows a good reproducibility and reversibility. The diffusions of different alcohols vapour were studied and the diffusion coefficients (D) were calculated. It is concluded that the diffusion of the vapours into the EB film follows Fickian kinetics.

  12. CO_2-assisted compression-adsorption hybrid for cooling and desalination

    International Nuclear Information System (INIS)

    Ali, Syed Muztuza; Chakraborty, Anutosh; Leong, Kai Choong

    2017-01-01

    Highlights: • Amalgamation of vapour compression and adsorption. • Thermodynamic frameworks of compression-adsorption hybrid. • 60% improvement in COP as compared with conventional CO_2 cooling system. • Energy recovery from CO_2 is used for cooling and desalination. • Energy from gas cooler accelerates the desalination process. - Abstract: This paper presents a novel compression-adsorption hybrid that symbiotically combines adsorption and CO_2 compression cooling devices. The seemingly low efficiency of each cycle individually is overcome by an amalgamation with the other. Hence, both heat and water vapour refrigerant mass are recovered for continuous cooling and desalination. Two different configurations are presented. The first configuration deals with a two-stage heat recovery system. At the first stage, heat is recovered from the compressed carbon dioxide to drive the adsorption device. The second stage heat recovery system internally exchanges heat between the low pressure and high pressure refrigerants of the CO_2 cycle. The second configuration is proposed with an additional third-stage heat recovery from the gas cooler to the high pressure evaporator of the adsorption cycle. The water vapour mass is recovered from bed-to-bed adsorption at relatively higher pressure. A detailed thermodynamic framework is presented to simulate the performances in terms of COP (coefficient of performance), SCP (specific cooling power), SDWP (specific daily water production), PR (performance ratio) and OCR (overall conversion ratio). It is found that the overall COP is improved by more than 60% as compared to the conventional CO_2 cycle, and in addition, the system generates 12.7 m"3 of desalinated water per tonne of silica gel per day as extra benefits. Furthermore, both the heat and mass recoveries improve the overall conversion ratio, which is almost double as compared to the conventional CO_2 cycle.

  13. Thermoluminescence characterisation of chemical vapour deposited diamond films

    CERN Document Server

    Mazzocchi, S; Bucciolini, M; Cuttone, G; Pini, S; Sabini, M G; Sciortino, S

    2002-01-01

    The thermoluminescence (TL) characteristics of a set of six chemical vapour deposited diamond films have been studied with regard to their use as off-line dosimeters in radiotherapy. The structural characterisation has been performed by means of Raman spectroscopy. Their TL responses have been tested with radiotherapy beams ( sup 6 sup 0 Co photons, photons and electrons from a linear accelerator (Linac), 26 MeV protons from a TANDEM accelerator) in the dose range 0.1-7 Gy. The dosimetric characterisation has yielded a very good reproducibility, a very low dependence of the TL response on the type of particle and independence of the radiation energy. The TL signal is not influenced by the dose rate and exhibits a very low thermal fading. Moreover, the sensitivity of the diamond samples compares favourably with that of standard TLD100 dosimeters.

  14. Chemical vapour deposition synthetic diamond: materials, technology and applications

    International Nuclear Information System (INIS)

    Balmer, R S; Brandon, J R; Clewes, S L; Dhillon, H K; Dodson, J M; Friel, I; Inglis, P N; Madgwick, T D; Markham, M L; Mollart, T P; Perkins, N; Scarsbrook, G A; Twitchen, D J; Whitehead, A J; Wilman, J J; Woollard, S M

    2009-01-01

    Substantial developments have been achieved in the synthesis of chemical vapour deposition (CVD) diamond in recent years, providing engineers and designers with access to a large range of new diamond materials. CVD diamond has a number of outstanding material properties that can enable exceptional performance in applications as diverse as medical diagnostics, water treatment, radiation detection, high power electronics, consumer audio, magnetometry and novel lasers. Often the material is synthesized in planar form; however, non-planar geometries are also possible and enable a number of key applications. This paper reviews the material properties and characteristics of single crystal and polycrystalline CVD diamond, and how these can be utilized, focusing particularly on optics, electronics and electrochemistry. It also summarizes how CVD diamond can be tailored for specific applications, on the basis of the ability to synthesize a consistent and engineered high performance product.

  15. Resonances of coherent population trapping in samarium vapours

    International Nuclear Information System (INIS)

    Kolachevsky, Nikolai N; Akimov, A V; Kiselev, N A; Papchenko, A A; Sorokin, Vadim N; Kanorskii, S I

    2001-01-01

    Resonances of coherent population trapping were detected in atomic vapours of the rare-earth element samarium. The coherent population trapping was produced by two external-cavity diode lasers (672 and 686 nm) in a Λ-system formed by the three levels of 154 Sm: the 4f 6 6s 2 ( 7 F 0 ) ground state, the first fine-structure 4f 6 6s 2 ( 7 F 1 ) sublevel of the ground state and the 4f 6 ( 7 F)6s6p( 3 P o ) 9 F o 1 upper level. The dependence of the spectral shapes and resonance contrasts on the polarisation of the laser beams and the direction of the applied magnetic field was studied. The obtained results were analysed. (nonlinear optical phenomena)

  16. Investigation of the summation of copper-vapour laser frequencies

    International Nuclear Information System (INIS)

    Karpukhin, Vyacheslav T; Konev, Yu B; Malikov, Mikhail M

    1998-01-01

    An investigation was made of the conversion of the copper-vapour laser radiation ( λ 1 = 0.51 μm and λ 2 = 0.578 μm) into UV radiation at the sum frequency (λ 3 = 0.271 μm) in a DKDP crystal. The operation of this frequency converter was compared for two magnifications of the laser cavity: M = 5 and 200. The best results were obtained for M = 200 (average UV radiation power 0.75 W, conversion efficiency 12%). A study was made of the characteristics of the formation of radiation pulses representing the two lines in the laser beam as a whole and in its weakly diverging core. In a low-divergence beam the yellow- and green-line pulses were emitted practically simultaneously with approximately the same peak power, which facilitated the sum-frequency generation. (nonlinear optical phenomena)

  17. Chemical vapour deposition of freestanding sub-60 nm graphene gyroids

    Science.gov (United States)

    Cebo, Tomasz; Aria, Adrianus I.; Dolan, James A.; Weatherup, Robert S.; Nakanishi, Kenichi; Kidambi, Piran R.; Divitini, Giorgio; Ducati, Caterina; Steiner, Ullrich; Hofmann, Stephan

    2017-12-01

    The direct chemical vapour deposition of freestanding graphene gyroids with controlled sub-60 nm unit cell sizes is demonstrated. Three-dimensional (3D) nickel templates were fabricated through electrodeposition into a selectively voided triblock terpolymer. The high temperature instability of sub-micron unit cell structures was effectively addressed through the early introduction of the carbon precursor, which stabilizes the metallized gyroidal templates. The as-grown graphene gyroids are self-supporting and can be transferred onto a variety of substrates. Furthermore, they represent the smallest free standing periodic graphene 3D structures yet produced with a pore size of tens of nm, as analysed by electron microscopy and optical spectroscopy. We discuss generality of our methodology for the synthesis of other types of nanoscale, 3D graphene assemblies, and the transferability of this approach to other 2D materials.

  18. Polarized Raman spectroscopy of chemically vapour deposited diamond films

    International Nuclear Information System (INIS)

    Prawer, S.; Nugent, K.W.; Weiser, P.S.

    1994-01-01

    Polarized micro-Raman spectra of chemically vapour deposited diamond films are presented. It is shown that important parameters often extracted from the Raman spectra such as the ratio of the diamond to non-diamond component of the films and the estimation of the level of residual stress depend on the orientation of the diamond crystallites with respect to the polarization of the incident laser beam. The dependence originates from the fact that the Raman scattering from the non-diamond components in the films is almost completely depolarized whilst the scattering from the diamond components is strongly polarized. The results demonstrate the importance of taking polarization into account when attempting to use Raman spectroscopy in even a semi-quantitative fashion for the assessment of the purity, perfection and stress in CVD diamond films. 8 refs., 1 tab. 2 figs

  19. Convective behaviour in vapour-gas-aerosol mixtures

    International Nuclear Information System (INIS)

    Clement, C.F.

    1986-01-01

    Unusual convective behaviour can occur in mixtures of gases and heavy vapour, including stabilization of mixtures hot at the base and 'upside-down' convection in mixtures hot at the top. Previous work produced a criterion for this behaviour which ignored the necessary presence of an aerosol. Modification arising from aerosol condensation is derived and is shown to involve the Lewis and condensation numbers of the mixture, as well as a quantity involving the temperature drop across a boundary layer. It becomes negligible at high temperatures, but can crucially affect the temperature for the onset of unusual behaviour. Aerosol formation produces an asymmetry between the convective forces in boundary layers in which the mixture is being heated and cooled, respectively, for example at the base and roof of a cavity. The convective behaviour discussed could occur in situations relevant to nuclear safety. (author)

  20. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  1. Impedimetric detection of alcohol vapours using nanostructured zinc ferrite.

    Science.gov (United States)

    Kannan, Padmanathan Karthick; Saraswathi, Ramiah

    2014-11-01

    A comparative study on the sensing characteristics of nanostructured zinc ferrite to three primary alcohols viz. methanol, ethanol and propanol has been carried out. The zinc ferrite has been prepared by a combustion method and characterized by XRD, FTIR, AFM and SEM. Impedance studies in the alcohol concentration range varying from 100 to 1000 ppm show definite variations in response to both the nature of the alcohol and its concentration. The nanostructured zinc ferrite shows the highest sensor response to methanol and least to propanol. Equivalent circuit modelling and calibration have been made for all the three alcohol sensors. The material shows a better selectivity to the alcohols compared to formaldehyde, ammonia and acetone vapours. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Water vapour retrieval using the Precision Solar Spectroradiometer

    Science.gov (United States)

    Raptis, Panagiotis-Ioannis; Kazadzis, Stelios; Gröbner, Julian; Kouremeti, Natalia; Doppler, Lionel; Becker, Ralf; Helmis, Constantinos

    2018-02-01

    The Precision Solar Spectroradiometer (PSR) is a new spectroradiometer developed at Physikalisch-Meteorologisches Observatorium Davos - World Radiation Center (PMOD-WRC), Davos, measuring direct solar irradiance at the surface, in the 300-1020 nm spectral range and at high temporal resolution. The purpose of this work is to investigate the instrument's potential to retrieve integrated water vapour (IWV) using its spectral measurements. Two different approaches were developed in order to retrieve IWV: the first one uses single-channel and wavelength measurements, following a theoretical water vapour high absorption wavelength, and the second one uses direct sun irradiance integrated at a certain spectral region. IWV results have been validated using a 2-year data set, consisting of an AERONET sun-photometer Cimel CE318, a Global Positioning System (GPS), a microwave radiometer profiler (MWP) and radiosonde retrievals recorded at Meteorological Observatorium Lindenberg, Germany. For the monochromatic approach, better agreement with retrievals from other methods and instruments was achieved using the 946 nm channel, while for the spectral approach the 934-948 nm window was used. Compared to other instruments' retrievals, the monochromatic approach leads to mean relative differences up to 3.3 % with the coefficient of determination (R2) being in the region of 0.87-0.95, while for the spectral approach mean relative differences up to 0.7 % were recorded with R2 in the region of 0.96-0.98. Uncertainties related to IWV retrieval methods were investigated and found to be less than 0.28 cm for both methods. Absolute IWV deviations of differences between PSR and other instruments were determined the range of 0.08-0.30 cm and only in extreme cases would reach up to 15 %.

  3. Heat transfer in vapour-liquid flow of carbon dioxide

    International Nuclear Information System (INIS)

    Yagov, V.V.

    2009-01-01

    During the last decade a number of studies of boiling heat transfer in carbon dioxide notably increase. As a field of CO 2 practical using corresponds to high reduced pressures, and a majority of available experimental data on CO 2 flow boiling even in submillimetric channels relate to turbulent liquid flow regimes, a possibility arises to develop sufficiently general method for HTC predicting. Under the above conditions nucleate boiling occurs up to rather high flow quality, even in annular flow regime due to extremely small size of an equilibrium vapour bubble. This conclusion is in agreement with the available experimental data. The predicting equation for nucleate boiling heat transfer developed by the present author in 1988 is valid for any nonmetallic liquid. A contribution of forced convection in heat transfer is calculated according to the Petukhov et al. equation with correction factor, which accounted for an effect of velocity increase due to evaporation. This effect can be essential at relatively small heat fluxes and rather high mass flow rates. The Reynolds analogy and homogeneous model are used in order to account for the convective heat transfer augmentation in two-phase flow. Due to low ratio of liquid and vapour densities at high reduced pressures the homogeneous approximation of two-phase flow seems to be warranted. A total heat transfer coefficient is calculated as an interpolated value of boiling and convective HTCs. The experimental data on CO 2 flow boiling related to regimes before heated wall dryout incipience are in rather good agreement with the calculations. (author)

  4. Physical properties of chemical vapour deposited nanostructured carbon thin films

    International Nuclear Information System (INIS)

    Mahadik, D.B.; Shinde, S.S.; Bhosale, C.H.; Rajpure, K.Y.

    2011-01-01

    Research highlights: In the present paper, nanostructured carbon films are grown using a natural precursor 'turpentine oil (C 10 H 16 )' as a carbon source in the simple thermal chemical vapour deposition method. The influence of substrate surface topography (viz. stainless steel, fluorine doped tin oxide coated quartz) and temperature on the evolution of carbon allotropes surfaces topography/microstructural and structural properties are investigated and discussed. - Abstract: A simple thermal chemical vapour deposition technique is employed for the deposition of carbon films by pyrolysing the natural precursor 'turpentine oil' on to the stainless steel (SS) and FTO coated quartz substrates at higher temperatures (700-1100 deg. C). In this work, we have studied the influence of substrate and deposition temperature on the evolution of structural and morphological properties of nanostructured carbon films. The films were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), contact angle measurements, Fourier transform infrared (FTIR) and Raman spectroscopy techniques. XRD study reveals that the films are polycrystalline exhibiting hexagonal and face-centered cubic structures on SS and FTO coated glass substrates respectively. SEM images show the porous and agglomerated surface of the films. Deposited carbon films show the hydrophobic nature. FTIR study displays C-H and O-H stretching vibration modes in the films. Raman analysis shows that, high ID/IG for FTO substrate confirms the dominance of sp 3 bonds with diamond phase and less for SS shows graphitization effect with dominant sp 2 bonds. It reveals the difference in local microstructure of carbon deposits leading to variation in contact angle and hardness, which is ascribed to difference in the packing density of carbon films, as observed also by Raman.

  5. Mixed garnet laser crystals for water vapour DIAL transmitter

    Science.gov (United States)

    Treichel, Rainer; Czeranowsky, Christoph; Ileri, Bilge; Petermann, Klaus; Huber, Günter

    2017-11-01

    There are more or less well established technologies such as the optical-parametric-oscillator (OPO), the Raman-laser, and the Ti-Sapphire laser, which are able to emit laser light in the region of the water vapour absorption lines. For WALES the regions of about 935 nm, 942 nm, and 944 nm have been identified as the most suitable wavelength ranges. However, each of these laser designs is highly sophisticated. Current baseline for WALES is the Ti-Sapphire laser. A fourth possibility to achieve these wavelength ranges is to shift the groundstate laser lines (938 nm and 946 nm) of the Nd:YAG laser by replacing Aluminium and Yttrium by other rare earth elements. Changes of the host lattice characteristics lead to a shift of the upper and lower laser levels. These modified crystals are summarized under the name of "Mixed Garnet" crystals. Only the Mixed Garnet lasers can be pumped directly with diode laser and use a direct approach to generate the required laser pulses without frequency conversion. Therefore no additional non-linear crystals are needed and a higher electric to optical efficiency is expected as well as single frequency operation using spectral tuning elements like etalons. Such lasers have the great potential to fulfil the requirements and to become the preferred transmitter concept for WALES as well as for follow up missions. Within a ESA study several crystal compositions have been grown, spectrally characterised and analysed. Absorbed space radiation energy in the crystal lattice causes colour centres, which can reabsorb the pump and laser wavelength and consequently reduce the laser gain considerably. Co-dopants such as Chromium and Cerium are able to suppress the colour centres and are candidates for effective radiation hardening. The results of the crystal tuning, the co-doping with different radiation hardeners and the radiation tests will be presented. There applicability for a space based water vapour DIAL transmitter will be discussed.

  6. Compressive laser ranging.

    Science.gov (United States)

    Babbitt, Wm Randall; Barber, Zeb W; Renner, Christoffer

    2011-12-15

    Compressive sampling has been previously proposed as a technique for sampling radar returns and determining sparse range profiles with a reduced number of measurements compared to conventional techniques. By employing modulation on both transmission and reception, compressive sensing in ranging is extended to the direct measurement of range profiles without intermediate measurement of the return waveform. This compressive ranging approach enables the use of pseudorandom binary transmit waveforms and return modulation, along with low-bandwidth optical detectors to yield high-resolution ranging information. A proof-of-concept experiment is presented. With currently available compact, off-the-shelf electronics and photonics, such as high data rate binary pattern generators and high-bandwidth digital optical modulators, compressive laser ranging can readily achieve subcentimeter resolution in a compact, lightweight package.

  7. Modelling water vapour permeability through atomic layer deposition coated photovoltaic barrier defects

    Energy Technology Data Exchange (ETDEWEB)

    Elrawemi, Mohamed, E-mail: Mohamed.elrawemi@hud.ac.uk [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom); Blunt, Liam; Fleming, Leigh [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom); Bird, David, E-mail: David.Bird@uk-cpi.com [Centre for Process Innovation Limited, Sedgefield, County Durham (United Kingdom); Robbins, David [Centre for Process Innovation Limited, Sedgefield, County Durham (United Kingdom); Sweeney, Francis [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom)

    2014-11-03

    Transparent barrier films such as Al{sub 2}O{sub 3} used for prevention of oxygen and/or water vapour permeation are the subject of increasing research interest when used for the encapsulation of flexible photovoltaic modules. However, the existence of micro-scale defects in the barrier surface topography has been shown to have the potential to facilitate water vapour ingress, thereby reducing cell efficiency and causing internal electrical shorts. Previous work has shown that small defects (≤ 3 μm lateral dimension) were less significant in determining water vapour ingress. In contrast, larger defects (≥ 3 μm lateral dimension) seem to be more detrimental to the barrier functionality. Experimental results based on surface topography segmentation analysis and a model presented in this paper will be used to test the hypothesis that the major contributing defects to water vapour transmission rate are small numbers of large defects. The model highlighted in this study has the potential to be used for gaining a better understanding of photovoltaic module efficiency and performance. - Highlights: • A model of water vapour permeation through barrier defects is presented. • The effect of the defects on the water vapour permeability is investigated. • Defect density correlates with water vapour permeability. • Large defects may dominate the permeation properties of the barrier film.

  8. Technical and economic working domains of industrial heat pumps: Part 2 - ammonia-water hybrid absorption-compression heat pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Ommen, Torben Schmidt; Markussen, Wiebke Brix

    2015-01-01

    The ammonia-water hybrid absorption-compression heat pump (HACHP) has been proposed as a relevant technology for industrial heat supply, especially for high sink temperatures and high temperature glides in the sink and source. This is due to the reduced vapour pressure and the non-isothermal phase...... change of the zeotropic mixture, ammonia-water. To evaluate to which extent these advantages can be translated into feasible heat pump solutions, the working domain of the HACHP is investigated based on technical and economic constraints. The HACHP working domain is compared to that of the best available...... vapour compression heat pump with natural working fluids. This shows that the HACHP increases the temperature lifts and heat supply temperatures that are feasible to produce with a heat pump. The HACHP is shown to be capable of delivering heat supply temperatures as high as 150 °C and temperature lifts...

  9. Technical and Economic Working Domains of Industrial Heat Pumps: Part 2 - Ammonia-Water Hybrid Absorption-Compression Heat Pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Ommen, Torben Schmidt; Markussen, Wiebke Brix

    2014-01-01

    The ammonia-water hybrid absorption-compression heat pump (HACHP) is a relevant technology for industrial heat supply, especially for high sink temperatures and high temperature glides in the sink and source. This is due to the reduced vapour pressure and the non-isothermal phase change...... of the zeotropic mixture, ammonia-water. To evaluate to which extent these advantages can be translated into feasible heat pump solutions, the working domain of the HACHP is investigated based on technical and economic constraints. The HACHP working domain is compared to that of the best possible vapour...... compression heat pump with natural working fluids. This shows that the HACHP increases the temperature lifts and heat supply temperatures that are feasible to produce with a heat pump. The HACHP is shown to be capable of delivering heat supply temperatures as high as 140 XC and temperature lifts up to 60 K...

  10. Evaluation of blast wave damage from very large unconfined vapour cloud explosions

    International Nuclear Information System (INIS)

    Munday, G.

    1975-01-01

    A mathematical model is described for estimating the damage potential from unconfined vapour cloud explosions. An attempt has been made to cover the salient details of the explosive phenomenon including finite flame accelerations and finite vapour cloud sizes. The model has been evaluated against two industrial incidents and the results extrapolated to large-volume vapour clouds. The authors conclude, on the evidence of this model, that great care must be taken in the evaluation of the explosion hazard from the probable occurrence of very large unconfined explosions even at distances in excess of 1 km from the centre of initiation. (author)

  11. Measurement of water vapour transport through a porous non-hygroscopic material in a temperature gradient

    DEFF Research Database (Denmark)

    Hansen, Thor; Padfield, Tim; Hansen, Kurt Kielsgaard

    2014-01-01

    This was an experiment to identify the driving potential for water vapour diffusion through porous materials in a temperature gradient. The specimen of mineral fibre insulation was placed between a space with controlled temperature and relative humidity and a space with a controlled, higher...... temperature, and a measured but not controlled relative humidity (RH). This assembly was allowed to reach equilibrium with no vapour movement between the spaces, as tested by a constant RH on each side and by zero flux of water vapour measured in the cold side chamber. The RH and temperature values were...

  12. Design and Implementation of Closed-loop PI Control Strategies in Real-time MATLAB Simulation Environment for Nonlinear and Linear ARMAX Models of HVAC Centrifugal Chiller Control Systems

    Directory of Open Access Journals (Sweden)

    Nicolae Tudoroiu

    2018-04-01

    Full Text Available The objective of this paper is to investigate three different approaches of modeling, design and discrete-time implementation of PI closed-loop control strategies in SIMULINK simulation environment, applied to a centrifugal chiller system. Centrifugal chillers are widely used in large building HVAC systems. The system consists of an evaporator, a condenser, a centrifugal compressor and an expansion valve. The overall system is an interconnection of two main control loops, namely the chilled water temperature inside the evaporator, and the refrigerant liquid level control in condenser. The centrifugal chiller dynamics model in a discrete-time state-space representation is of high complexity in terms of dimension and encountered nonlinearities. For simulation purpose the centrifugal chiller model is simplified by using different approaches, especially the development of linear polynomials ARMAX and ARX models. The aim to build linear ARMAX models for centrifugal chiller is to simplify considerable the control design strategies that are investigated in this research paper. The novelty of this research is a new controller design approach, more precisely an improved version of proportional – integral control, the so called Proportional-Integral-Plus control for systems with time delay, based on linear ARMAX models. It is conceived within the context of non-minimum state space control system that “seems to be the natural description of a discrete-time transfer function, since its dimension is dictated by the complete structure of the model”. The effectiveness of this new controller design, its implementation simplicity, convergence speed and robustness are proved in the last section of the paper.

  13. Mechanical vapor compression Desalination plant at Trombay

    International Nuclear Information System (INIS)

    Adak, A.K.; Kishore, G.; Srivastava, V.K.; Tewari, P.K.

    2007-01-01

    Desalination plants based on Mechanical Vapour Compression (MVC) technology are inherently the most thermodynamically efficient. The thermodynamic efficiency of the MVC process is derived from the application of the heat pump principle. A single unit of two-effect MVC desalination pilot plant of capacity 50 m3/day has recently been commissioned at Trombay, Mumbai. The desalination unit is very compact and unique of its kind in the seawater desalination technologies and is being operated by using electricity only. Horizontal tube thin film spray desalination evaporators are used for efficient heat transfer. It is suitable for a site, where feed water is highly saline and condenser cooling water is absent and where a thermal heat source is not available. The unit produces high quality water, nearly demineralized (DM) quality directly from seawater. There is no need of polishing unit and product water can be utilized directly as make up of boiler feed and for other high quality process water requirements in the industries. This paper includes the design and highlights the technical features of this unit. (author)

  14. Enhancements of thermal conductivities with Cu, CuO, and carbon nanotube nanofluids and application of MWNT/water nanofluid on a water chiller system

    Directory of Open Access Journals (Sweden)

    Lin Mark

    2011-01-01

    Full Text Available Abstract In this study, enhancements of thermal conductivities of ethylene glycol, water, and synthetic engine oil in the presence of copper (Cu, copper oxide (CuO, and multi-walled carbon nanotube (MWNT are investigated using both physical mixing method (two-step method and chemical reduction method (one-step method. The chemical reduction method is, however, used only for nanofluid containing Cu nanoparticle in water. The thermal conductivities of the nanofluids are measured by a modified transient hot wire method. Experimental results show that nanofluids with low concentration of Cu, CuO, or carbon nanotube (CNT have considerably higher thermal conductivity than identical base liquids. For CuO-ethylene glycol suspensions at 5 vol.%, MWNT-ethylene glycol at 1 vol.%, MWNT-water at 1.5 vol.%, and MWNT-synthetic engine oil at 2 vol.%, thermal conductivity is enhanced by 22.4, 12.4, 17, and 30%, respectively. For Cu-water at 0.1 vol.%, thermal conductivity is increased by 23.8%. The thermal conductivity improvement for CuO and CNT nanofluids is approximately linear with the volume fraction. On the other hand, a strong dependence of thermal conductivity on the measured time is observed for Cu-water nanofluid. The system performance of a 10-RT water chiller (air conditioner subject to MWNT/water nanofluid is experimentally investigated. The system is tested at the standard water chiller rating condition in the range of the flow rate from 60 to 140 L/min. In spite of the static measurement of thermal conductivity of nanofluid shows only 1.3% increase at room temperature relative to the base fluid at volume fraction of 0.001 (0.1 vol.%, it is observed that a 4.2% increase of cooling capacity and a small decrease of power consumption about 0.8% occur for the nanofluid system at a flow rate of 100 L/min. This result clearly indicates that the enhancement of cooling capacity is not just related to thermal conductivity alone. Dynamic effect, such as

  15. Prediction of vapour-liquid and vapour-liquid-liquid equilibria of nitrogen-hydrocarbon mixtures used in J-T refrigerators

    Science.gov (United States)

    Narayanan, Vineed; Venkatarathnam, G.

    2018-03-01

    Nitrogen-hydrocarbon mixtures are widely used as refrigerants in J-T refrigerators operating with mixtures, as well as in natural gas liquefiers. The Peng-Robinson equation of state has traditionally been used to simulate the above cryogenic process. Multi parameter Helmholtz energy equations are now preferred for determining the properties of natural gas. They have, however, been used only to predict vapour-liquid equilibria, and not vapour-liquid-liquid equilibria that can occur in mixtures used in cryogenic mixed refrigerant processes. In this paper the vapour-liquid equilibrium of binary mixtures of nitrogen-methane, nitrogen-ethane, nitrogen-propane, nitrogen-isobutane and three component mixtures of nitrogen-methane-ethane and nitrogen-methane-propane have been studied with the Peng-Robinson and the Helmholtz energy equations of state of NIST REFPROP and compared with experimental data available in the literature.

  16. Long distance spin communication in chemical vapour deposited graphene

    Science.gov (United States)

    Kamalakar, M. Venkata; Groenveld, Christiaan; Dankert, André; Dash, Saroj P.

    2015-04-01

    Graphene is an ideal medium for long-distance spin communication in future spintronic technologies. So far, the prospect is limited by the smaller sizes of exfoliated graphene flakes and lower spin transport properties of large-area chemical vapour-deposited (CVD) graphene. Here we demonstrate a high spintronic performance in CVD graphene on SiO2/Si substrate at room temperature. We show pure spin transport and precession over long channel lengths extending up to 16 μm with a spin lifetime of 1.2 ns and a spin diffusion length ~6 μm at room temperature. These spin parameters are up to six times higher than previous reports and highest at room temperature for any form of pristine graphene on industrial standard SiO2/Si substrates. Our detailed investigation reinforces the observed performance in CVD graphene over wafer scale and opens up new prospects for the development of lateral spin-based memory and logic applications.

  17. Thermalisation of high energy electrons and positrons in water vapour

    Science.gov (United States)

    Munoz, A.; Blanco, F.; Limao-Vieira, P.; Thorn, P. A.; Brunger, M. J.; Buckman, S. J.; Garcia, G.

    2008-07-01

    In this study we describe a method to simulate single electron tracks of electrons in molecular gases, particularly in water vapour, from relatively high energies, where Born (Inokuti 1971) approximation is supposed to be valid, down to thermal energies paying special attention to the low energy secondary electrons which are abundantly generated along the energy degradation procedure. Experimental electron scattering cross sections (Munoz et al. 2007) and energy loss spectra (Thorn et al. 2007) have been determined, where possible, to be used as input parameters of the simulating program. These experimental data have been complemented with optical potential calculation (Blanco and Garcia 2003) providing a complete set of interaction probability functions for each type of collision which could take place in the considered energy range: elastic, ionization, electronic excitation, vibrational and rotational excitation. From the simulated track structure (Munoz et al. 2005) information about energy deposition and radiation damage at the molecular level can be derived. A similar procedure is proposed to the study of single positron tracks in gases. Due to the lack of experimental data for positron interaction with molecules, especially for those related to energy loss and excitation cross sections, some distribution probability data have been derived from those of electron scattering by introducing positron characteristics as positroniun formation. Preliminary results for argon are presented discussing also the utility of the model to biomedical applications based on positron emitters.

  18. Initiation of a boiling liquid expanding vapour explosion

    Energy Technology Data Exchange (ETDEWEB)

    McDevitt, C.A.; Chan, C.K.; Steward, F.R.; Tennankore, K.N.; Venart, J.E.S.

    1991-06-01

    Boiling liquid expanding vapour explosions (BLEVEs) occur when a pressure liquefied gas tank is burst and the fluid is ejected to the atmosphere. As the liquid is exposed to a lower pressure it boils violently, causing an explosion which destroys the container. One litre tanks were filled with propane or R12, heated, and caused to rupture at specific test conditions to determine the parameters required for a BLEVE. Results showed that the energy stored in the liquid under pressure relative to the liquid at atmospheric conditions was a quantity which can be used to predict a BLEVE for the particular apparatus and conditions used. The possible importance of the development of a shock wave within the container during a BLEVE was noted. A shock tube was used to study the shock waves generated during a BLEVE. Temperature, liquid volume, rupture location, rupture area, and the fluid involved were varied. The pressure was measured vs time for periods immediately after the rupture. Photographs of the formation of pressure waves were obtained using spark Schlieren photography and showed that the BLEVE phenomenon is definitely a shock-related event. Pressure information was also gathered during BLEVEs of one litre cylinders, and this information is compared to that from the shock tube. Shock tube data showed that transverse waves formed from the initial pressure wave could be amplified. 37 refs., 54 figs., 11 tabs.

  19. Adsorption Of Water And Benzene Vapour In Mesoporous Materials

    Directory of Open Access Journals (Sweden)

    Paulina Taba

    2008-11-01

    Full Text Available Mesoporous materials have attracted the attention of many researchers due to the potential applications promised by the materials. This article discusses adsorption of water and benzene vapour in mesoporous materials (mesoporous silica: MCM-41, MCM-48 and their modification. MCM-41 and MCM-48 were synthesized hydrothermally at 100 oC using cethyltrimethylammonium chloride or dodecyltrimethylammonium bromide for MCM-41 (C16 or MCM-41 (C12 respectively and a mixture of cethyltrimethylammonium bromide and Triton X-100 for MCM-48 as templates. Their modifications were conducted by silylation of MCM-41 (C16 and MCM-48 with trimethylchloro silane (MCM16-TMCS and MCM48-TMCS and t-butyldimethylchloro silane (MCM16-TBDMCS and MCM48-TBDMCS. Results showed that MCM-41 and MCM-48 materials had hydrophobic features which were shown in the small amount of water adsorption at low P/P0. The hydrophobicity of samples used in this study decrease in the sequence: MCM-41 (C16 > MCM-48 > MCM-41 (C12. The hydrophobicity increased when MCM-41 and MCM-48 were silylated with TMCS or TBDMCS. All unsilylated MCM materials show higher affinity to benzene at low P/P0 than the silylated samples. The results of water and benzene adsorption showed that silylated samples are promising candidates as selective adsorbents for organic compounds.

  20. Water vapour and ozone profiles in the midlatitude upper troposphere

    Directory of Open Access Journals (Sweden)

    G. Vaughan

    2005-01-01

    Full Text Available We present an investigation of upper tropospheric humidity profiles measured with a standard radiosonde, the Vaisala RS80-A, and a commercial frost-point hygrometer, the Snow White. Modifications to the Snow White, to enable the mirror reflectivity and Peltier cooling current to be monitored during flight, were found to be necessary to determine when the instrument was functioning correctly; a further modification to prevent hydrometeors entering the inlet was also implemented. From 23 combined flights of an ozonesonde, radiosonde and Snow White between September 2001 and July 2002, clear agreement was found between the two humidity sensors, with a mean difference of <2% in relative humidity from 2 to 10km, and 2.2% between 10 and 13km. This agreement required a correction to the radiosonde humidity, as described by Miloshevich et al. (2001. Using this result, the dataset of 324 ozonesonde/RS80-A profiles measured from Aberystwyth between 1991 and 2002 was examined to derive statistics for the distribution of water vapour and ozone. Supersaturation with respect to ice was frequently seen at the higher levels - 24% of the time in winter between 8 and 10km. The fairly uniform distribution of relative humidity persisted to 120% in winter, but decreased rapidly above 100% in summer.

  1. Vapour transport growth of ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Mofor, A.C.; Bakin, A.S.; Elshaer, A.; Waag, A. [Technical University Braunschweig, Institute of Semiconductor Technology, Braunschweig (Germany); Fuhrmann, D.; Hangleiter, A. [Technical University Braunschweig, Institute of Applied Physics, Braunschweig (Germany); Bertram, F.; Christen, J. [University of Magdeburg, Department of Solid State Physics, Magdeburg (Germany)

    2007-07-15

    The fabrication of low-dimensional ZnO structures has attracted enormous attention as such nanostructures are expected to pave the way for many interesting applications in optoelectronics, spin electronics gas sensor technology and biomedicine. Many reported fabrication methods, especially for ZnO nanorods are mostly based on catalyst-assisted growth techniques that employ metal-organic sources and other contaminating agents like graphite to grow ZnO nanorods at relatively high temperatures. We report on catalyst-free vapour-phase epitaxy growth of ZnO nanorods on 6H-SiC and (11-20)Al{sub 2}O{sub 3} using purely elemental sources at relatively low temperatures and growth pressure. ZnO nanorods with widths of 80-900 nm and lengths of up to 12 {mu}m were obtained. Nanorod density on the order of 10{sup 9} cm{sup -2} with homogenous luminescence and high purity was also noted. (orig.)

  2. Initiation of a boiling liquid expanding vapour explosion

    Energy Technology Data Exchange (ETDEWEB)

    McDevitt, C.A.

    1990-01-01

    Boiling liquid expanding vapour explosions (BLEVEs) occur when a pressure liquefied gas tank is burst and the fluid is ejected to the atmosphere. As the liquid is exposed to a lower pressure it boils violently, causing an explosion which destroys the container. One litre tanks were filled with propane or R12, heated, and caused to rupture at specific test conditions to determine the parameters required for a BLEVE. Results showed that the energy stored in the liquid under pressure relative to the liquid at atmospheric conditions was a quantity which can be used to predict a BLEVE for the particular apparatus and conditions used. The possible importance of the development of a shock wave within the container during a BLEVE was noted. A shock tube was used to study the shock waves generated during a BLEVE. Temperature, liquid volume, rupture location, rupture area, and the fluid involved were varied. The pressure was measured vs time for periods immediately after the rupture. Photographs of the formation of pressure waves were obtained using spark Schlieren photography. Similarities to waves measured during detonations in ducts were noted. Pressure information was also gathered during BLEVEs of one litre cylinders, and this data is compared to that from the shock tube. Shock tube data showed that transverse waves formed from the initial pressure wave could be amplified. 37 refs., 54 figs., 11 tabs.

  3. Poly(methyl methacrylate) films for organic vapour sensing

    CERN Document Server

    Capan, R; Hassan, A K; Tanrisever, T

    2003-01-01

    Optical constants and fabrication parameters are investigated using surface plasmon resonance (SPR) studies on spun films of poly(methyl methacrylate) (PMMA) derivatives in contact with two different dielectric media. A value of 1.503 for the refractive index of PMMA films produced from a solution having concentration of 1 mg ml sup - sup 1 at the speed of 3000 rpm is in close agreement with the data obtained from ellipsometric measurements. The film thickness shows a power-law dependence on the spin speed but the thickness increases almost linearly with the concentration of the spreading solution. These results are in good agreement with the hydrodynamic theory for a low-viscosity and highly volatile liquid. On the basis of SPR measurements under dynamic conditions, room temperature response of PMMA films to benzene vapours is found to be fast, highly sensitive and reversible. The sensitivity of detection of toluene, ethyl benzene and m-xylene is much smaller than that of benzene.

  4. Chemical vapour deposition of vanadium oxide thermochromic thin films

    Science.gov (United States)

    Piccirillo, Clara

    Thermochromic materials change optical properties, such as transmittance or reflectance, with a variation in temperature. An ideal intelligent (smart) material will allow solar radiation in through a window in cold conditions, but reflect that radiation in warmer conditions. The variation in the properties is often associated with a phase change, which takes place at a definite temperature, and is normally reversible. Such materials are usually applied to window glass as thin films. This thesis presents the work on the development of thermochromic vanadium (IV) oxide (VO2) thin films - both undoped and doped with tungsten, niobium and gold nanoparticles - which could be employed as solar control coatings. The films were deposited using Chemical Vapour Deposition (CVD), using improved Atmospheric Pressure (APCVD), novel Aerosol Assisted (AACVD) and novel hybrid AP/AACVD techniques. The effects of dopants on the metalto- semiconductor transition temperature and transmittance/reflectance characteristics were also investigated. This work significantly increased the understanding of the mechanisms behind thermochromic behaviour, and resulted in thermochromic materials based on VO2 with greatly improved properties.

  5. Tungsten Deposition on Graphite using Plasma Enhanced Chemical Vapour Deposition

    International Nuclear Information System (INIS)

    Sharma, Uttam; Chauhan, Sachin S; Sharma, Jayshree; Sanyasi, A K; Ghosh, J; Choudhary, K K; Ghosh, S K

    2016-01-01

    The tokamak concept is the frontrunner for achieving controlled thermonuclear reaction on earth, an environment friendly way to solve future energy crisis. Although much progress has been made in controlling the heated fusion plasmas (temperature ∼ 150 million degrees) in tokamaks, technological issues related to plasma wall interaction topic still need focused attention. In future, reactor grade tokamak operational scenarios, the reactor wall and target plates are expected to experience a heat load of 10 MW/m 2 and even more during the unfortunate events of ELM's and disruptions. Tungsten remains a suitable choice for the wall and target plates. It can withstand high temperatures, its ductile to brittle temperature is fairly low and it has low sputtering yield and low fuel retention capabilities. However, it is difficult to machine tungsten and hence usages of tungsten coated surfaces are mostly desirable. To produce tungsten coated graphite tiles for the above-mentioned purpose, a coating reactor has been designed, developed and made operational at the SVITS, Indore. Tungsten coating on graphite has been attempted and successfully carried out by using radio frequency induced plasma enhanced chemical vapour deposition (rf -PECVD) for the first time in India. Tungsten hexa-fluoride has been used as a pre-cursor gas. Energy Dispersive X-ray spectroscopy (EDS) clearly showed the presence of tungsten coating on the graphite samples. This paper presents the details of successful operation and achievement of tungsten coating in the reactor at SVITS. (paper)

  6. Radiation induced vapour phase grafting of styrene onto fluorinated substrates

    International Nuclear Information System (INIS)

    Dargaville, T.; Hill, D.; George, G.; Cardona, F.

    2000-01-01

    Full text: Polytetrafluoroethylene (PTFE) is well known for being inert towards heat, solvents and harsh chemicals. However, in contrast, PTFE is extremely sensitive to radiation suffering from a dramatic decrease in mechanical strength even when exposed to low doses. In this study we have used a copolymer of PTFE, poly(tetrafluoroethylene-co-perfluoropropylvinyl ether) (PFA). The effect of the ether comonomer is to render the polymer melt processable, lower the crystallinity and increase the radical yield when compared with PTFE. When grafting styrene to PFA using a radiation initiated process, the resulting polymer has the desirable chemical and thermal resistance of the PFA substrate combined with the functionality of the styrene, however, due to the incidental degradative effect of radiation on the PFA substrate it is important to find conditions where the best graft is achieved without exposing the substrate to extraneous levels of radiation. We have successfully grafted styrene to PFA by simultaneously exposing PFA to styrene vapour and gamma radiation. This process was found to be independent of dose rate at low dose rates suggesting a diffusion controlled mechanism. The penetration of the graft into the PFA substrate was measured by mapping a cross-section using micro-probe Raman spectroscopy

  7. Optical pulse compression

    International Nuclear Information System (INIS)

    Glass, A.J.

    1975-01-01

    The interest in using large lasers to achieve a very short and intense pulse for generating fusion plasma has provided a strong impetus to reexamine the possibilities of optical pulse compression at high energy. Pulse compression allows one to generate pulses of long duration (minimizing damage problems) and subsequently compress optical pulses to achieve the short pulse duration required for specific applications. The ideal device for carrying out this program has not been developed. Of the two approaches considered, the Gires--Tournois approach is limited by the fact that the bandwidth and compression are intimately related, so that the group delay dispersion times the square of the bandwidth is about unity for all simple Gires--Tournois interferometers. The Treacy grating pair does not suffer from this limitation, but is inefficient because diffraction generally occurs in several orders and is limited by the problem of optical damage to the grating surfaces themselves. Nonlinear and parametric processes were explored. Some pulse compression was achieved by these techniques; however, they are generally difficult to control and are not very efficient. (U.S.)

  8. SiC fibre by chemical vapour deposition on tungsten filament

    Indian Academy of Sciences (India)

    Unknown

    SiC fibre by chemical vapour deposition on tungsten filament ... CMCs), in defence and industrial applications. SiC has attractive ... porosity along with chemical purity. This is lacking .... reactor. Since mercury is very toxic it should be removed.

  9. Influence of ion size asymmetry on the properties of ionic liquid-vapour interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bresme, Fernando [Department of Chemistry, Imperial College London, London SW7 2AZ (United Kingdom); Gonzalez-Melchor, Minerva [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Avenida San Rafael Atlixco 186, Colonia Vicentina, 09340 Mexico D.F. (Mexico); Alejandre, Jose [Departamento de QuImica, Universidad Autonoma Metropolitana-Iztapalapa, Avenida San Rafael Atlixco 186, Colonia Vicentina, 09340 Mexico D.F. (Mexico)

    2005-11-16

    The influence of ion size asymmetry on the properties of ionic liquid-vapour interfaces is investigated using molecular dynamics simulations of the soft primitive model. Ion size asymmetry results in charge separation at the liquid-vapour interface and therefore in a local violation of the electroneutrality condition. For moderate size asymmetries the electrostatic potential at the interface can reach values of the order of 0.1 V. Size asymmetry plays a very important role in determining ion adsorption at the liquid-vapour interface of ionic mixtures. The interfacial adsorption of the bigger component results in an increase of the electrostatic potential, and a reduction of the interfacial surface tension. Our results show that ionic mixtures provide a very efficient way to tune the electrostatics and surface properties of ionic liquid-vapour interfaces.

  10. Ethanol vapour sensing properties of screen printed WO3 thick films

    Indian Academy of Sciences (India)

    TECS

    trations. The WO3 thick films exhibit excellent ethanol vapour sensing properties with a maximum sensitivity ... methanol, acetone, isopropanol and acetic acid, have been reported .... maximum sensitivity was obtained at an operating tem-.

  11. Influence of ion size asymmetry on the properties of ionic liquid-vapour interfaces

    International Nuclear Information System (INIS)

    Bresme, Fernando; Gonzalez-Melchor, Minerva; Alejandre, Jose

    2005-01-01

    The influence of ion size asymmetry on the properties of ionic liquid-vapour interfaces is investigated using molecular dynamics simulations of the soft primitive model. Ion size asymmetry results in charge separation at the liquid-vapour interface and therefore in a local violation of the electroneutrality condition. For moderate size asymmetries the electrostatic potential at the interface can reach values of the order of 0.1 V. Size asymmetry plays a very important role in determining ion adsorption at the liquid-vapour interface of ionic mixtures. The interfacial adsorption of the bigger component results in an increase of the electrostatic potential, and a reduction of the interfacial surface tension. Our results show that ionic mixtures provide a very efficient way to tune the electrostatics and surface properties of ionic liquid-vapour interfaces

  12. Fission product vapour - aerosol interactions in the containment: simulant fuel studies

    International Nuclear Information System (INIS)

    Beard, A.M.; Benson, C.G.; Bowsher, B.R.

    1988-12-01

    Experiments have been conducted in the Falcon facility to study the interaction of fission product vapours released from simulant fuel samples with control rod aerosols. The aerosols generated from both the control rod and fuel sample were chemically distinct and had different deposition characteristics. Extensive interaction was observed between the fission product vapours and the control rod aerosol. The two dominant mechanisms were condensation of the vapours onto the aerosol, and chemical reactions between the two components; sorption phenomena were believed to be only of secondary importance. The interaction of fission product vapours and reactor materials aerosols could have a major impact on the transport characteristics of the radioactive emission from a degrading core. (author)

  13. The thermotidal exciting function for water vapour absorption of solar radiation

    Directory of Open Access Journals (Sweden)

    M. BONAFEDE

    1976-06-01

    Full Text Available The thermotidal exciting function J is considered, for
    the absorption of solar radiation by water vapour, according to the model
    derived by Siebert. The Mugge-Moller formula for water vapour absorption
    is integrated numerically, using experimental data for the water vapour
    concentration in the troposphere and the stratosphere. It appears that
    Siebort's formula is a reasonable approximation at low tropospheric levels
    but it dramatically overestimates the water vapour thermotidal heating
    in the upper troposphere and in the stratosphere. It seems thus possible
    that, if the correct vertical profile is employed for J , the amplitudes and
    phases of the diurnal temperature oscillations and of the tidal wind speeds
    may suffer significant changes from those previously calculated and possibly explain the three hours delay of the observed phases from the computed values.

  14. Alcohol vapours sensor based on thin polyaniline salt film and quartz crystal microbalance.

    Science.gov (United States)

    Ayad, Mohamad M; Torad, Nagy L

    2009-06-15

    A sensor based on the quartz crystal microbalance (QCM) technique was developed for detection of a number of primary aliphatic alcohols such as ethanol, methanol, 1-propanol, and 2-propanol vapours. Detection was based on a sensitive and a thin film of polyaniline, emeraldine salt (ES), coated the QCM electrode. The frequency shifts (Delta f) of the QCM were increased due to the vapour absorption into the ES film. The values of Delta f were found to be linearly correlated with the concentrations of alcohols vapour in mg L(-1). The changes in frequency are due to the hydrophilic character of the ES and the electrostatic interaction as well as the type of the alcohol. The sensor shows a good reproducibility and reversibility. The diffusion and diffusion coefficient (D) of different alcohols vapour were determined. It was found that the sensor follows Fickian kinetics.

  15. Organic Vapour Sensing Properties of Area-Ordered and Size-Controlled Silicon Nanopillar

    Directory of Open Access Journals (Sweden)

    Wei Li

    2016-11-01

    Full Text Available Here, a silicon nanopillar array (Si-NPA was fabricated. It was studied as a room-temperature organic vapour sensor, and the ethanol and acetone gas sensing properties were detected with I-V curves. I-V curves show that these Si-NPA gas sensors are sensitive to ethanol and acetone organic vapours. The turn-on threshold voltage is about 0.5 V and the operating voltage is 3 V. With 1% ethanol gas vapour, the response time is 5 s, and the recovery time is 15 s. Furthermore, an evaluation of the gas sensor stability for Si-NPA was performed. The gas stability results are acceptable for practical detections. These excellent sensing characteristics can mainly be attributed to the change of the overall dielectric constant of Si-NPA caused by the physisorption of gas molecules on the pillars, and the filling of the gas vapour in the voids.

  16. The transition time induced narrow linewidth of the electromagnetically induced transparency in caesium vapour

    International Nuclear Information System (INIS)

    Li Luming; Peng Xiang; Liu Cheng; Guo Hong; Chen Xuzong

    2004-01-01

    We observed a narrow linewidth (∼60 kHz) in a Doppler-broadened system showing electromagnetically induced transparency in caesium atomic vapour. The transition time induced reduction of the linewidth is illustrated both theoretically and experimentally

  17. Sensing response of copper phthalocyanine salt dispersed glass with organic vapours

    Energy Technology Data Exchange (ETDEWEB)

    Ridhi, R.; Sachdeva, Sheenam; Saini, G. S. S.; Tripathi, S. K., E-mail: surya@pu.ac.in [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (INDIA) Fax: +91-172-2783336; Tel.:+91-172-2544362 (India)

    2016-05-06

    Copper Phthalocyanine and other Metal Phthalocyanines are very flexible and tuned easily to modify their structural, spectroscopic, optical and electrical properties by either functionalizing them with various substituent groups or by replacing or adding a ligand to the central metal atom in the phthalocyanine ring and accordingly can be made sensitive and selective to various organic species or gaseous vapours. In the present work, we have dispersed Copper Phthalocyanine Salt (CuPcS) in sol-gel glass form using chemical route sol-gel method and studied its sensing mechanism with organic vapours like methanol and benzene and found that current increases onto their exposure with vapours. A variation in the activation energies was also observed with exposure of vapours.

  18. DESIGN of MICRO CANTILEVER BEAM for VAPOUR DETECTION USING COMSOL MULTI PHYSICS SOFTWARE

    OpenAIRE

    Sivacoumar R; Parvathy JM; Pratishtha Deep

    2015-01-01

    This paper gives an overview of micro cantilever beam of various shapes and materials for vapour detection. The design of micro cantilever beam, analysis and simulation is done for each shape. The simulation is done using COMSOL Multi physics software using structural mechanics and chemical module. The simulation results of applied force and resulting Eigen frequencies will be analyzed for different beam structures. The vapour analysis is done using flow cell that consists of chemical pill...

  19. Vapour pressures and enthalpies of vaporization of a series of the ferrocene derivatives

    International Nuclear Information System (INIS)

    Emel'yanenko, Vladimir N.; Verevkin, Sergey P.; Krol, Olesya V.; Varushchenko, Raisa M.; Chelovskaya, Nelly V.

    2007-01-01

    Vapour pressures of the ferrocene, ferrocene-methanol, benzyl-ferrocene, and benzoyl-ferrocene have been determined by the transpiration method. The molar enthalpies of sublimation Δ cr g H m and of vaporization Δ l g H m have been determined from the temperature dependence of the vapour pressure. The molar enthalpies of fusion of these compounds were measured by d.s.c. The measured data sets of vaporization, sublimation, and fusion enthalpies were checked for internal consistency

  20. Sampling system of atmospheric water vapour for analysis of the γ sub(D) relationship

    International Nuclear Information System (INIS)

    Foloni, L.L.; Villa Nova, N.A.; Salati, E.

    1979-01-01

    The development of a system to water vapour air, for natural isotopic composition analysis of hydrogen is presented. The system uses molecular sieve, type '4A', without cooling agent and permits the choice of a sampling time, variyng from a few minutes to many hours, through the control of the admission of vapour flux. The system has good performance in field conditions, with errors of the order of + -3,0 0 /00 in the γ sub(D)( 0 /00) measurements [pt

  1. Thermodynamic properties of the liquid Hg-Tl alloys determined from vapour pressure measurements

    Directory of Open Access Journals (Sweden)

    Gierlotka W.

    2002-01-01

    Full Text Available The partial vapour pressure of mercury over liquid Hg-Tl liquid solutions were determined in the temperature range from 450 to 700 K by direct vapour pressure measurements carried out with the quartz gauge. From the measured ln pHg vs. T relationships activities of mercury were determined. Using Redlich-Kister formulas logarithms of the activity coefficients were described with the following equations: From which all thermodynamic functions in the solutions can be derived.

  2. The vapour pressures over saturated aqueous solutions of sodium and potassium acetates, chlorates, and perchlorates

    Energy Technology Data Exchange (ETDEWEB)

    Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel)]. E-mail: apelblat@bgu.ac.il; Manzurola, Emanuel [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel)

    2007-08-15

    Vapour pressures of water over saturated solutions of sodium acetate, potassium acetate, sodium perchlorate, and potassium perchlorate were determined over the (278 to 318) K temperature range and compared with available in the literature data. The cases of saturated solutions of sodium chlorate and potassium chlorate are also considered. The determined vapour pressures were used to obtain the water activities, the osmotic coefficients, and the molar enthalpies of vaporization in considered systems.

  3. Hybrid compression/absorption type heat utilization system (eco-energy city project)

    Energy Technology Data Exchange (ETDEWEB)

    Karimata, T.; Susami, S.; Ogawa, Y. [Research and Development Dept., EBARA Corp., Kanagawa pref. (Japan)

    1999-07-01

    This research is intended to develop a 'hybrid compression/absorption type heat utilization system' by combining an absorption process with a compression process in one circulation cycle. This system can produce chilling heat for ice thermal storage by utilizing low-temperature waste heat (lower than 100 C) which is impossible to treat with a conventional absorption chiller. It means that this system will be able to solve the problem of a timing mismatch between waste heat and heat demand. The working fluid used in this proposed system should be suitable for producing ice, be safe, and not damage the ozone layer. In this project, new working fluids were searched as substitutes for the existing H{sub 2}O/LiBr or NH{sub 3}/H{sub 2}O. The interim results of this project in 1997, a testing unit using NH{sub 3}/H{sub 2}O was built for demonstration of the system and evaluation of its characteristics, and R134a/E181 was found to be one of the good working fluid for this system. The COP (ratio of energy of ice produced to electric power provided) of this system using R134a/E181 is expected to achieve 5.5 by computer simulation. The testing unit with this working fluid was built recently and prepared for the tests to confirm the result of the simulation. (orig.)

  4. Isentropic Compression of Argon

    International Nuclear Information System (INIS)

    Oona, H.; Solem, J.C.; Veeser, L.R.; Ekdahl, C.A.; Rodriquez, P.J.; Younger, S.M.; Lewis, W.; Turley, W.D.

    1997-01-01

    We are studying the transition of argon from an insulator to a conductor by compressing the frozen gas isentropically to pressures at which neighboring atomic orbitals overlap sufficiently to allow some electron motion between atoms. Argon and the other rare gases have closed electron shells and therefore remain montomic, even when they solidify. Their simple structure makes it likely that any measured change in conductivity is due to changes in the atomic structure, not in molecular configuration. As the crystal is compressed the band gap closes, allowing increased conductivity. We have begun research to determine the conductivity at high pressures, and it is our intention to determine the compression at which the crystal becomes a metal

  5. Pulsed Compression Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Roestenberg, T. [University of Twente, Enschede (Netherlands)

    2012-06-07

    The advantages of the Pulsed Compression Reactor (PCR) over the internal combustion engine-type chemical reactors are briefly discussed. Over the last four years a project concerning the fundamentals of the PCR technology has been performed by the University of Twente, Enschede, Netherlands. In order to assess the feasibility of the application of the PCR principle for the conversion methane to syngas, several fundamental questions needed to be answered. Two important questions that relate to the applicability of the PCR for any process are: how large is the heat transfer rate from a rapidly compressed and expanded volume of gas, and how does this heat transfer rate compare to energy contained in the compressed gas? And: can stable operation with a completely free piston as it is intended with the PCR be achieved?.

  6. Medullary compression syndrome

    International Nuclear Information System (INIS)

    Barriga T, L.; Echegaray, A.; Zaharia, M.; Pinillos A, L.; Moscol, A.; Barriga T, O.; Heredia Z, A.

    1994-01-01

    The authors made a retrospective study in 105 patients treated in the Radiotherapy Department of the National Institute of Neoplasmic Diseases from 1973 to 1992. The objective of this evaluation was to determine the influence of radiotherapy in patients with medullary compression syndrome in aspects concerning pain palliation and improvement of functional impairment. Treatment sheets of patients with medullary compression were revised: 32 out of 39 of patients (82%) came to hospital by their own means and continued walking after treatment, 8 out of 66 patients (12%) who came in a wheelchair or were bedridden, could mobilize by their own after treatment, 41 patients (64%) had partial alleviation of pain after treatment. In those who came by their own means and did not change their characteristics, functional improvement was observed. It is concluded that radiotherapy offers palliative benefit in patients with medullary compression syndrome. (authors). 20 refs., 5 figs., 6 tabs

  7. Thermoeconomic analysis of an integrated multi-effect desalination thermal vapor compression (MED-TVC) system with a trigeneration system using triple-pressure HRSG

    Science.gov (United States)

    Ghaebi, Hadi; Abbaspour, Ghader

    2018-05-01

    In this research, thermoeconomic analysis of a multi-effect desalination thermal vapor compression (MED-TVC) system integrated with a trigeneration system with a gas turbine prime mover is carried out. The integrated system comprises of a compressor, a combustion chamber, a gas turbine, a triple-pressure (low, medium and high pressures) heat recovery steam generator (HRSG) system, an absorption chiller cycle (ACC), and a multi-effect desalination (MED) system. Low pressure steam produced in the HRSG is used to drive absorption chiller cycle, medium pressure is used in desalination system and high pressure superheated steam is used for heating purposes. For thermodynamic and thermoeconomic analysis of the proposed integrated system, Engineering Equation Solver (EES) is used by employing mass, energy, exergy, and cost balance equations for each component of system. The results of the modeling showed that with the new design, the exergy efficiency in the base design will increase to 57.5%. In addition, thermoeconomic analysis revealed that the net power, heating, fresh water and cooling have the highest production cost, respectively.

  8. Estudo do resfriamento de carcaças de frango em chiller de imersão em água

    OpenAIRE

    Carciofi, Bruno Augusto Mattar

    2005-01-01

    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Alimentos O resfriamento industrial de carcaças de frango é normalmente efetuado em tanques de imersão em água (chillers). Nesta etapa, além da redução da temperatura, ocorre absorção de água pelas carcaças. Neste trabalho foram estudados diversos aspectos relacionados com a redução da temperatura e com a absorção de água por carcaças resfriadas por imersão, além ...

  9. Intrinsic stress of bismuth oxide thin films: effect of vapour chopping and air ageing

    International Nuclear Information System (INIS)

    Patil, R B; Puri, R K; Puri, V

    2008-01-01

    Bismuth oxide thin films of thickness 1000 A 0 have been prepared by thermal oxidation (in air) of vacuum evaporated bismuth thin films (on glass substrate) at different oxidation temperatures and duration. Both the vapour chopped and nonchopped bismuth oxide thin films showed polycrystalline and polymorphic structure. The monoclinic bismuth oxide was found to be predominant in both the cases. The effect of vapour chopping and air exposure for 40 days on the intrinsic stress of bismuth oxide thin films has been studied. The vapour chopped films showed low (3.92 - 4.80 x 10 9 N/m 2 ) intrinsic stress than those of nonchopped bismuth oxide thin films (5.77 - 6.74 x 10 9 N/m 2 ). Intrinsic stress was found to increase due to air ageing. The effect of air ageing on the vapour chopped films was found low. The vapour chopped films showed higher packing density. Higher the packing density, lower the film will age. The process of chopping vapour flow creates films with less inhomogenety i.e. a low concentration of flaws and non-planar defects which results in lower intrinsic stress

  10. Optimisation of lean vapour compression (LVC) as an option for post-combustion CO2 capture: net present value maximisation

    NARCIS (Netherlands)

    Sanchez Fernandez, E.; Bergsma, E.J.; Miguel Mercader, F. de; Goetheer, E.L.V.; Vlugt, T.J.H.

    2012-01-01

    Many process schemes have been proposed in literature to decrease the energy demand of amine based carbon dioxide processes. These process schemes are generally analysed in terms of energy demand savings and compared to a common baseline based on the solvent monoethanolamine (MEA). In this work, the

  11. Technical and economic working domains of industrial heat pumps: Part 1 - single stage vapour compression heat pumps

    DEFF Research Database (Denmark)

    Ommen, Torben Schmidt; Jensen, Jonas Kjær; Markussen, Wiebke Brix

    2015-01-01

    A large amount of operational and economic constraints limit the applicability of heat pumps operated with natural working fluids. The limitations are highly dependent on the integration of heat source and sink streams. An evaluation of feasible operating conditions was carried out considering......, the transcritical R744 expands the working domain for low sink outlet temperatures....

  12. Graph Compression by BFS

    Directory of Open Access Journals (Sweden)

    Alberto Apostolico

    2009-08-01

    Full Text Available The Web Graph is a large-scale graph that does not fit in main memory, so that lossless compression methods have been proposed for it. This paper introduces a compression scheme that combines efficient storage with fast retrieval for the information in a node. The scheme exploits the properties of the Web Graph without assuming an ordering of the URLs, so that it may be applied to more general graphs. Tests on some datasets of use achieve space savings of about 10% over existing methods.

  13. The water vapour flux above Switzerland and its role in the August 2005 extreme precipitation and flooding

    Energy Technology Data Exchange (ETDEWEB)

    N' Dri Koffi, Ernest; Maetzler, Christian [Bern Univ. (Switzerland). Inst. of Applied Physics; Graham, Edward [Bern Univ. (Switzerland). Inst. of Applied Physics; University of the Highlands and Islands, Stornoway, Scotland (United Kingdom). Lews Castle College

    2013-10-15

    The water budget approach is applied to an atmospheric box above Switzerland (hereafter referred to as the 'Swiss box') to quantify the atmospheric water vapour flux using ECMWF ERA-Interim reanalyses. The results confirm that the water vapour flux through the Swiss box is highly temporally variable, ranging from 1 to 5 x 10{sup 7} kg/s during settled anticyclonic weather, but increasing in size by a factor of ten or more during high speed currents of water vapour. Overall, Switzerland and the Swiss box 'import' more water vapour than it 'exports', but the amount gained remains only a small fraction (1% to 5%) of the total available water vapour passing by. High inward water vapour fluxes are not necessarily linked to high precipitation episodes. The water vapour flux during the August 2005 floods, which caused severe damage in central Switzerland, is examined and an assessment is made of the computed water vapour fluxes compared to high spatio-temporal rain gauge and radar observations. About 25% of the incoming water vapour flux was stored in Switzerland. The computed water vapour fluxes from ECMWF data compare well with the mean rain gauge observations and the combined rain-gauge radar precipitation products. (orig.)

  14. WAVE-E: The WAter Vapour European-Explorer Mission

    Science.gov (United States)

    Jimenez-LLuva, David; Deiml, Michael; Pavesi, Sara

    2017-04-01

    In the last decade, stratosphere-troposphere coupling processes in the Upper Troposphere Lower Stratosphere (UTLS) have been increasingly recognized to severely impact surface climate and high-impact weather phenomena. Weakened stratospheric circumpolar jets have been linked to worldwide extreme temperature and high-precipitation events, while anomalously strong stratospheric jets can lead to an increase in surface winds and tropical cyclone intensity. Moreover, stratospheric water vapor has been identified as an important forcing for global decadal surface climate change. In the past years, operational weather forecast and climate models have adapted a high vertical resolution in the UTLS region in order to capture the dynamical processes occurring in this highly stratified region. However, there is an evident lack of available measurements in the UTLS region to consistently support these models and further improve process understanding. Consequently, both the IPCC fifth assessment report and the ESA-GEWEX report 'Earth Observation and Water Cycle Science Priorities' have identified an urgent need for long-term observations and improved process understanding in the UTLS region. To close this gap, the authors propose the 'WAter Vapour European - Explorer' (WAVE-E) space mission, whose primary goal is to monitor water vapor in the UTLS at 1 km vertical, 25 km horizontal and sub-daily temporal resolution. WAVE-E consists of three quasi-identical small ( 500 kg) satellites (WAVE-E 1-3) in a constellation of Sun-Synchronous Low Earth Orbits, each carrying a limb sounding and cross-track scanning mid-infrared passive spectrometer (824 cm-1 to 829 cm-1). The core of the instruments builds a monolithic, field-widened type of Michelson interferometer without any moving parts, rendering it rigid and fault tolerant. Synergistic use of WAVE-E and MetOp-NG operational satellites is identified, such that a data fusion algorithm could provide water vapour profiles from the

  15. The atmospheric chemical vapour deposition of coatings on glass

    International Nuclear Information System (INIS)

    Sanderson, Kevin David

    1996-01-01

    The deposition of thin films of indium oxide, tin doped indium oxide (ITO) and titanium nitride for solar control applications have been investigated by Atmospheric Chemical Vapour Deposition (APCVD). Experimental details of the deposition system and the techniques used to characterise the films are presented. Results from investigations into the deposition parameters, the film microstructure and film material properties are discussed. A range of precursors were investigated for the deposition of indium oxide. The effect of pro-mixing the vaporised precursor with an oxidant source and the deposition temperature has been studied. Polycrystalline In 2 O 3 films with a resistivity of 1.1 - 3x10 -3 Ω cm were obtained with ln(thd) 3 , oxygen and nitrogen. The growth of ITO films from ln(thd) 3 , oxygen and a range of tin dopants is also presented. The effect of the dopant precursor, the doping concentration, deposition temperature and the effect of additives on film growth and microstructure is discussed. Control over the preferred orientation growth of ITO has been achieved by the addition of acetate species during film growth. Insitu infra-red spectroscopy has been used to identify the gas phase species and identify the species responsible for the film modification. ITO films with a resistivities of 1.5 - 4x10 -4 Ω cm have been achieved. The deposition of titanium nitride by the APCVD of Ti(NMe 2 ) 4 and a mixture of Ti(NMe 2 ) 4 and ammonia is reported. Contamination of the films and pro-reaction between the precursors in the gas phase is discussed, and the synthesis of new precursors for the deposition of titanium nitride is reported. New precursors have been synthesised under anaerobic conditions and characterised by infra-red spectroscopy, 1 H and 13 C NMR, mass spectrometry, thermal gravemetric analysis and three by single crystal X-ray diffraction. Deposition of titanium nitride utilising two new precursors is reported. (author)

  16. Venera 15: Water vapour in the middle atmosphere of Venus

    Science.gov (United States)

    Ignatiev, N. I.; Moroz, V. I.; Zasova, L. V.; Khatuntsev, I. V.

    1999-01-01

    In 1983, spectra of Venus in the region of 6-40 μm were measured by means of the Fourier Spectrometer aboard the Venera 15 orbiter. It covered local solar times from 4 a.m. to 10 a.m. and from 4 p.m. to 10 p.m. in the latitude range from -65° up to 87°. The results of an extended processing and analysis of these data are presented. Time and spatial variations of the water vapour were found. Most of the measurements fall in the range of 5-15 ppm, which is close to the early results. The effective altitude of sounding is approximately equal to the altitude where the optical depth τ = 1. Two latitude regions can be distinguished: (A) 20° 60°, which are characterised by different altitudes of the level of τ = 1: 62 and 55 km respectively. Mean mixing ratios near this level in the two regions are almost the same, but the partial pressures and mass densities in region (B) are 2-4 times greater than those in region (A). In region (A) a weak dayside maximum and a nightside minimum were observed. Region (B) is of inhomogeneous structure, and the retrieved mixing ratio has greater uncertainty and may probably change from the detection limit of 1 ppm up to 30 ppm. Although the retrieval of H2O mixing ratio altitude profile from the Venera 15 data appeared to be impossible, indirect indications were found that at least in region (A) the mixing ratio decreases with altitude.

  17. Compressible generalized Newtonian fluids

    Czech Academy of Sciences Publication Activity Database

    Málek, Josef; Rajagopal, K.R.

    2010-01-01

    Roč. 61, č. 6 (2010), s. 1097-1110 ISSN 0044-2275 Institutional research plan: CEZ:AV0Z20760514 Keywords : power law fluid * uniform temperature * compressible fluid Subject RIV: BJ - Thermodynamics Impact factor: 1.290, year: 2010

  18. Temporal compressive sensing systems

    Science.gov (United States)

    Reed, Bryan W.

    2017-12-12

    Methods and systems for temporal compressive sensing are disclosed, where within each of one or more sensor array data acquisition periods, one or more sensor array measurement datasets comprising distinct linear combinations of time slice data are acquired, and where mathematical reconstruction allows for calculation of accurate representations of the individual time slice datasets.

  19. Compression of Infrared images

    DEFF Research Database (Denmark)

    Mantel, Claire; Forchhammer, Søren

    2017-01-01

    best for bits-per-pixel rates below 1.4 bpp, while HEVC obtains best performance in the range 1.4 to 6.5 bpp. The compression performance is also evaluated based on maximum errors. These results also show that HEVC can achieve a precision of 1°C with an average of 1.3 bpp....

  20. Gas compression infrared generator

    International Nuclear Information System (INIS)

    Hug, W.F.

    1980-01-01

    A molecular gas is compressed in a quasi-adiabatic manner to produce pulsed radiation during each compressor cycle when the pressure and temperature are sufficiently high, and part of the energy is recovered during the expansion phase, as defined in U.S. Pat. No. 3,751,666; characterized by use of a cylinder with a reciprocating piston as a compressor

  1. The millennium water vapour drop in chemistry–climate model simulations

    Directory of Open Access Journals (Sweden)

    S. Brinkop

    2016-07-01

    Full Text Available This study investigates the abrupt and severe water vapour decline in the stratosphere beginning in the year 2000 (the "millennium water vapour drop" and other similarly strong stratospheric water vapour reductions by means of various simulations with the state-of-the-art Chemistry-Climate Model (CCM EMAC (ECHAM/MESSy Atmospheric Chemistry Model. The model simulations differ with respect to the prescribed sea surface temperatures (SSTs and whether nudging is applied or not. The CCM EMAC is able to most closely reproduce the signature and pattern of the water vapour drop in agreement with those derived from satellite observations if the model is nudged. Model results confirm that this extraordinary water vapour decline is particularly obvious in the tropical lower stratosphere and is related to a large decrease in cold point temperature. The drop signal propagates under dilution to the higher stratosphere and to the poles via the Brewer–Dobson circulation (BDC. We found that the driving forces for this significant decline in water vapour mixing ratios are tropical sea surface temperature (SST changes due to a coincidence with a preceding strong El Niño–Southern Oscillation event (1997/1998 followed by a strong La Niña event (1999/2000 and supported by the change of the westerly to the easterly phase of the equatorial stratospheric quasi-biennial oscillation (QBO in 2000. Correct (observed SSTs are important for triggering the strong decline in water vapour. There are indications that, at least partly, SSTs contribute to the long period of low water vapour values from 2001 to 2006. For this period, the specific dynamical state of the atmosphere (overall atmospheric large-scale wind and temperature distribution is important as well, as it causes the observed persistent low cold point temperatures. These are induced by a period of increased upwelling, which, however, has no corresponding pronounced signature in SSTs anomalies in the tropics

  2. Water vapour and methane coupling in the stratosphere observed using SCIAMACHY solar occultation measurements

    Directory of Open Access Journals (Sweden)

    S. Noël

    2018-04-01

    Full Text Available An improved stratospheric water vapour data set has been retrieved from SCIAMACHY/ENVISAT solar occultation measurements. It is similar to that successfully applied to methane and carbon dioxide. There is now a consistent set of data products for the three constituents covering the altitudes 17–45 km, the latitude range between about 50 and 70° N, and the period August 2002 to April 2012. The new water vapour concentration profiles agree with collocated results from ACE-FTS and MLS/Aura to within  ∼  5 %. A significant positive linear change in water vapour for the time 2003–2011 is observed at lower stratospheric altitudes with a value of about 0.015 ± 0.008 ppmv year−1 around 17 km. Between 30 and 37 km the changes become significantly negative (about −0.01 ± 0.008 ppmv year−1; all errors are 2σ values. The combined analysis of the SCIAMACHY methane and water vapour time series shows the expected anti-correlation between stratospheric methane and water vapour and a clear temporal variation related to the Quasi-Biennial Oscillation (QBO. Above about 20 km most of the additional water vapour is attributed to the oxidation of methane. In addition short-term fluctuations and longer-term variations on a timescale of 5–6 years are observed. The SCIAMACHY data confirm that at lower altitudes the amount of water vapour and methane are transported from the tropics to higher latitudes via the shallow branch of the Brewer–Dobson circulation.

  3. Solvation-based vapour pressure model for (solvent + salt) systems in conjunction with the Antoine equation

    International Nuclear Information System (INIS)

    Senol, Aynur

    2013-01-01

    Highlights: • Vapour pressures of (solvent + salt) systems have been estimated through a solvation-based model. • Two structural forms of the generalized solvation model using the Antoine equation have been performed. • A simplified concentration-dependent vapour pressure model has been also processed. • The model reliability analysis has been performed in terms of a log-ratio objective function. • The reliability of the models has been interpreted in terms of the statistical design factors. -- Abstract: This study deals with modelling the vapour pressure of a (solvent + salt) system on the basis of the principles of LSER. The solvation model framework clarifies the simultaneous impact of several physical variables such as the vapour pressure of a pure solvent estimated by the Antoine equation, the solubility and solvatochromic parameters of the solvent and the physical properties of the ionic salt. It has been analyzed independently the performance of two structural forms of the generalized model, i.e., a relation depending on an integration of the properties of the solvent and the ionic salt and a relation on a reduced property-basis. A simplified concentration-dependent vapour pressure model has been also explored and implemented on the relevant systems. The vapour pressure data of sixteen (solvent + salt) systems have been processed to analyze statistically the reliability of existing models in terms of a log–ratio objective function. The proposed vapour pressure models match relatively well the observed performance, yielding the overall design factors of 1.066 and 1.073 for the solvation-based models with the integrated and reduced properties, and 1.008 for the concentration-based model, respectively

  4. Continuous measurements of isotopic composition of water vapour on the East Antarctic Plateau

    Directory of Open Access Journals (Sweden)

    M. Casado

    2016-07-01

    Full Text Available Water stable isotopes in central Antarctic ice cores are critical to quantify past temperature changes. Accurate temperature reconstructions require one to understand the processes controlling surface snow isotopic composition. Isotopic fractionation processes occurring in the atmosphere and controlling snowfall isotopic composition are well understood theoretically and implemented in atmospheric models. However, post-deposition processes are poorly documented and understood. To quantitatively interpret the isotopic composition of water archived in ice cores, it is thus essential to study the continuum between surface water vapour, precipitation, surface snow and buried snow. Here, we target the isotopic composition of water vapour at Concordia Station, where the oldest EPICA Dome C ice cores have been retrieved. While snowfall and surface snow sampling is routinely performed, accurate measurements of surface water vapour are challenging in such cold and dry conditions. New developments in infrared spectroscopy enable now the measurement of isotopic composition in water vapour traces. Two infrared spectrometers have been deployed at Concordia, allowing continuous, in situ measurements for 1 month in December 2014–January 2015. Comparison of the results from infrared spectroscopy with laboratory measurements of discrete samples trapped using cryogenic sampling validates the relevance of the method to measure isotopic composition in dry conditions. We observe very large diurnal cycles in isotopic composition well correlated with temperature diurnal cycles. Identification of different behaviours of isotopic composition in the water vapour associated with turbulent or stratified regime indicates a strong impact of meteorological processes in local vapour/snow interaction. Even if the vapour isotopic composition seems to be, at least part of the time, at equilibrium with the local snow, the slope of δD against δ18O prevents us from identifying

  5. Compressible Fluid Suspension Performance Testing

    National Research Council Canada - National Science Library

    Hoogterp, Francis

    2003-01-01

    ... compressible fluid suspension system that was designed and installed on the vehicle by DTI. The purpose of the tests was to evaluate the possible performance benefits of the compressible fluid suspension system...

  6. Analysis of the cavitating flow induced by an ultrasonic horn – Numerical 3D simulation for the analysis of vapour structures and the assessment of erosion-sensitive areas

    Directory of Open Access Journals (Sweden)

    Mottyll Stephan

    2014-03-01

    Full Text Available This paper reports the outcome of a numerical study of ultrasonic cavitation using a CFD flow algorithm based on a compressible density-based finite volume method with a low-Machnumber consistent flux function and an explicit time integration [15; 18] in combination with an erosion-detecting flow analysis procedure. The model is validated against erosion data of an ultrasonic horn for different gap widths between the horn tip and a counter sample which has been intensively investigated in previous material studies at the Ruhr University Bochum [23] as well as on first optical in-house flow measurement data which is presented in a companion paper [13]. Flow features such as subharmonic cavitation oscillation frequencies as well as constricted vapour cloud structures can also be observed by the vapour regions predicted in our simulation as well as by the detected collapse event field (collapse detector [12]. With a statistical analysis of transient wall loads we can determine the erosion sensitive areas qualitatively. Our simulation method can reproduce the influence of the gap width on vapour structure and on location of cavitation erosion.

  7. Vapours of US and EU Market Leader Electronic Cigarette Brands and Liquids Are Cytotoxic for Human Vascular Endothelial Cells

    OpenAIRE

    Putzhammer, Raphaela; Doppler, Christian; Jakschitz, Thomas; Heinz, Katharina; F?rste, Juliane; Danzl, Katarina; Messner, Barbara; Bernhard, David

    2016-01-01

    The present study was conducted to provide toxicological data on e-cigarette vapours of different e-cigarette brands and liquids from systems viewed as leaders in the e-cigarette market and to compare e-cigarette vapour toxicity to the toxicity of conventional strong high-nicotine cigarette smoke. Using an adapted version of a previously constructed cigarette smoke constituent sampling device, we collected the hydrophilic fraction of e-cigarette vapour and exposed human umbilical vein endothe...

  8. LZ-Compressed String Dictionaries

    OpenAIRE

    Arz, Julian; Fischer, Johannes

    2013-01-01

    We show how to compress string dictionaries using the Lempel-Ziv (LZ78) data compression algorithm. Our approach is validated experimentally on dictionaries of up to 1.5 GB of uncompressed text. We achieve compression ratios often outperforming the existing alternatives, especially on dictionaries containing many repeated substrings. Our query times remain competitive.

  9. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2013-01-01

    We introduce a new compression scheme for labeled trees based on top trees [3]. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  10. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2015-01-01

    We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  11. Digital cinema video compression

    Science.gov (United States)

    Husak, Walter

    2003-05-01

    The Motion Picture Industry began a transition from film based distribution and projection to digital distribution and projection several years ago. Digital delivery and presentation offers the prospect to increase the quality of the theatrical experience for the audience, reduce distribution costs to the distributors, and create new business opportunities for the theater owners and the studios. Digital Cinema also presents an opportunity to provide increased flexibility and security of the movies for the content owners and the theater operators. Distribution of content via electronic means to theaters is unlike any of the traditional applications for video compression. The transition from film-based media to electronic media represents a paradigm shift in video compression techniques and applications that will be discussed in this paper.

  12. Fingerprints in compressed strings

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Cording, Patrick Hagge

    2017-01-01

    In this paper we show how to construct a data structure for a string S of size N compressed into a context-free grammar of size n that supports efficient Karp–Rabin fingerprint queries to any substring of S. That is, given indices i and j, the answer to a query is the fingerprint of the substring S......[i,j]. We present the first O(n) space data structures that answer fingerprint queries without decompressing any characters. For Straight Line Programs (SLP) we get O(log⁡N) query time, and for Linear SLPs (an SLP derivative that captures LZ78 compression and its variations) we get O(log⁡log⁡N) query time...

  13. The Droplets Condensate Centering in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads

    Science.gov (United States)

    Seryakov, A. V.; Shakshin, S. L.; Alekseev, A. P.

    2017-11-01

    The results of experimental studies of the process of condensate microdroplets centering contained in the moving moist vapour in the vapour channel of short heat pipes (HPs) for large thermal loads are presented. A vapour channel formed by capillary-porous insert in the form of the inner Laval-liked nozzle along the entire length of the HP. In the upper cover forming a condensation surface in the HP, on the diametrical line are installed capacitive sensors, forming three capacitors located at different distances from the longitudinal axis of the vapour channel. With increasing heat load and the boil beginning in the evaporator a large amount of moist vapour in the vapour channel of HP occur the pressure pulsation with frequency of 400-500 Hz and amplitude up to 1·104Pa. These pulsations affect the moving of the inertial droplets subsystem of the vapour and due to the heterogeneity of the velocity profile around the particle flow in the vapour channel at the diameter of microdroplets occurs transverse force, called the Saffman force and shear microdroplets to the center of vapour channel. Using installed in the top cover capacitors we can record the radial displacement of the condensable microdroplets.

  14. WSNs Microseismic Signal Subsection Compression Algorithm Based on Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Zhouzhou Liu

    2015-01-01

    Full Text Available For wireless network microseismic monitoring and the problems of low compression ratio and high energy consumption of communication, this paper proposes a segmentation compression algorithm according to the characteristics of the microseismic signals and the compression perception theory (CS used in the transmission process. The algorithm will be collected as a number of nonzero elements of data segmented basis, by reducing the number of combinations of nonzero elements within the segment to improve the accuracy of signal reconstruction, while taking advantage of the characteristics of compressive sensing theory to achieve a high compression ratio of the signal. Experimental results show that, in the quantum chaos immune clone refactoring (Q-CSDR algorithm for reconstruction algorithm, under the condition of signal sparse degree higher than 40, to be more than 0.4 of the compression ratio to compress the signal, the mean square error is less than 0.01, prolonging the network life by 2 times.

  15. MEDUSA: The ExoMars experiment for in-situ monitoring of dust and water vapour

    Science.gov (United States)

    Colangeli, L.; Lopez-Moreno, J. J.; Nørnberg, P.; Della Corte, V.; Esposito, F.; Mazzotta Epifani, E.; Merrison, J.; Molfese, C.; Palumbo, P.; Rodriguez-Gomez, J. F.; Rotundi, A.; Visconti, G.; Zarnecki, J. C.; The International Medusa Team

    2009-07-01

    Dust and water vapour are fundamental components of the Martian atmosphere. In view of tracing the past environmental conditions on Mars, that possibly favoured the appearing of life forms, it is important to study the present climate and its evolution. Here dust and water vapour have (and have had) strong influence. Of major scientific interest is the quantity and physical, chemical and electrical properties of dust and the abundance of water vapour dispersed in the atmosphere and their exchange with the surface. Moreover, in view of the exploration of the planet with automated systems and in the future by manned missions, it is of primary importance to analyse the hazards linked to these environmental factors. The Martian Environmental Dust Systematic Analyser (MEDUSA) experiment, included in the scientific payload of the ESA ExoMars mission, accommodates a complement of sensors, based on optical detection and cumulative mass deposition, that aims to study dust and water vapour in the lower Martian atmosphere. The goals are to study, for the first time, in-situ and quantitatively, physical properties of the airborne dust, including the cumulative dust mass flux, the dust deposition rate, the physical and electrification properties, the size distribution of sampled particles and the atmospheric water vapour abundance versus time.

  16. Performance analysis of a potassium-steam two stage vapour cycle

    International Nuclear Information System (INIS)

    Mitachi, Kohshi; Saito, Takeshi

    1983-01-01

    It is an important subject to raise the thermal efficiency in thermal power plants. In present thermal power plants which use steam cycle, the plant thermal efficiency has already reached 41 to 42 %, steam temperature being 839 K, and steam pressure being 24.2 MPa. That is, the thermal efficiency in a steam cycle is facing a limit. In this study, analysis was made on the performance of metal vapour/steam two-stage Rankine cycle obtained by combining a metal vapour cycle with a present steam cycle. Three different combinations using high temperature potassium regenerative cycle and low temperature steam regenerative cycle, potassium regenerative cycle and steam reheat and regenerative cycle, and potassium bleed cycle and steam reheat and regenerative cycle were systematically analyzed for the overall thermal efficiency, the output ratio and the flow rate ratio, when the inlet temperature of a potassium turbine, the temperature of a potassium condenser, and others were varied. Though the overall thermal efficiency was improved by lowering the condensing temperature of potassium vapour, it is limited by the construction because the specific volume of potassium in low pressure section increases greatly. In the combinatipn of potassium vapour regenerative cycle with steam regenerative cycle, the overall thermal efficiency can be 58.5 %, and also 60.2 % if steam reheat and regenerative cycle is employed. If a cycle to heat steam with the bled vapor out of a potassium vapour cycle is adopted, the overall thermal efficiency of 63.3 % is expected. (Wakatsuki, Y.)

  17. Compressed sensing electron tomography

    International Nuclear Information System (INIS)

    Leary, Rowan; Saghi, Zineb; Midgley, Paul A.; Holland, Daniel J.

    2013-01-01

    The recent mathematical concept of compressed sensing (CS) asserts that a small number of well-chosen measurements can suffice to reconstruct signals that are amenable to sparse or compressible representation. In addition to powerful theoretical results, the principles of CS are being exploited increasingly across a range of experiments to yield substantial performance gains relative to conventional approaches. In this work we describe the application of CS to electron tomography (ET) reconstruction and demonstrate the efficacy of CS–ET with several example studies. Artefacts present in conventional ET reconstructions such as streaking, blurring of object boundaries and elongation are markedly reduced, and robust reconstruction is shown to be possible from far fewer projections than are normally used. The CS–ET approach enables more reliable quantitative analysis of the reconstructions as well as novel 3D studies from extremely limited data. - Highlights: • Compressed sensing (CS) theory and its application to electron tomography (ET) is described. • The practical implementation of CS–ET is outlined and its efficacy demonstrated with examples. • High fidelity tomographic reconstruction is possible from a small number of images. • The CS–ET reconstructions can be more reliably segmented and analysed quantitatively. • CS–ET is applicable to different image content by choice of an appropriate sparsifying transform

  18. Burned gas and unburned mixture composition prediction in biodiesel-fuelled compression igniton engine

    International Nuclear Information System (INIS)

    Chuepeng, S.; Komintarachati, C.

    2009-01-01

    A prediction of burned gas and unburned mixture composition from a variety of methyl ester based bio diesel combustion in compression ignition engine, in comparison with conventional diesel fuel is presented. A free-energy minimisation scheme was used to determine mixture composition. Firstly, effects of bio diesel type were studied without exhaust gas recirculation (EGR). The combustion of the higher hydrogen-to-carbon molar ratio (H/C) bio diesel resulted in lower carbon dioxide and oxygen emissions but higher water vapour in the exhaust gases, compared to those of lower H/C ratios. At the same results also show that relative air-to-fuel ratio, that bio diesel combustion gases contain a higher amount of water vapour and a higher level of carbon dioxide compared to those of diesel. Secondly, influences of EGR (burned gas fraction) addition to bio diesel-fuelled engine on unburned mixture were simulated. For both diesel and bio diesel, the increased burned gas fraction addition to the fresh charge increased carbon dioxide and water vapour emissions while lowering oxygen content, especially for the bio diesel case. The prediction was compared with experimental results from literatures; good agreement was found. This can be considered to be a means for explaining some phenomenon occurring in bio diesel-fuelled engines. (author)

  19. The magnetic vapour shield effect at divertor plates during plasma disruptions

    International Nuclear Information System (INIS)

    Piazza, G.; Goel, B.; Hoebel, W.; Wuerz, H.; Landman, I.

    1995-01-01

    Hard disruptions in a TOKAMAK cause a large thermal load on the divertor plates with an instantaneous ablation of a part of the heated material. The produced vapour cloud screens the plasma facing component from the direct interaction with the disrupting plasma (vapour shield effect). In order to quantify the damage to the divertor the magneto-hydrodynamic behaviour of the expanding vapour cloud has been investigated using an extended version of the 1-dimensional Lagrangian hydrodynamic code KATACO. Modelling of the magnetic field effects on the expanding plasma takes into account that the magnetic field is oblique to the divertor (1 1/2 dimensional model). The ''Radiation Heat Conduction Approximation'' has been used for describing the radiative energy transport. In this paper results are presented assuming graphite as divertor material, irradiated with a proton beam of an energy density of 12MJ/m 2 and a duration of 100μs. (orig.)

  20. Effect of Liquid/Vapour Maldistribution on the Performance of Plate Heat Exchanger Evaporators

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Kærn, Martin Ryhl; Ommen, Torben Schmidt

    2015-01-01

    Plate heat exchangers are often applied as evaporators in industrial refrigeration and heat pump systems. In the design and modelling of such heat exchangers the flow and liquid/vapour distribution is often assumed to be ideal. However, maldistribution may occur and will cause each channel...... to behave differently due to the variation of the mass flux and vapour quality. To evaluate the effect of maldistribution on the performance of plate heat exchangers, a numerical model is developed in which the mass, momentum and energy balances are applied individually to each channel, including suitable...... correlations for heat transfer and pressure drop. The flow distribution on both the refrigerant and secondary side is determined based on equal pressure drop while the liquid/vapour distribution is imposed to the model. Results show that maldistribution may cause up to a 25 % reduction of the overall heat...

  1. Effect of Organic Vapour on Porous Alumina Based Moisture Sensor in Dry Gases

    Directory of Open Access Journals (Sweden)

    Saakshi DHANEKAR

    2009-08-01

    Full Text Available A capacitive porous alumina based trace moisture sensor in the range of 50 to 500 ppm (V was fabricated by low cost sol-gel technique. The cross-sensitivities due to the presence of organic vapours like ethanol, methanol, acetone and benzene were studied. The change in response and recovery time with ppm for moisture sensing was also calculated. The experimental results conclude that moisture sensor is responsive to the polar organic vapours but has almost negligible response to the nonpolar molecules like benzene. Response of the sensor to the organic vapours as compared to the moisture sensitivity is very less. The effect of ambient temperature was found to be negligible.

  2. Effect of water vapour absorption on hydroxyl temperatures measured from Svalbard

    Directory of Open Access Journals (Sweden)

    J. M. Chadney

    2017-03-01

    Full Text Available We model absorption by atmospheric water vapour of hydroxyl airglow emission using the HIgh-resolution TRANsmission molecular absorption database (HITRAN2012. Transmission coefficients are provided as a function of water vapour column density for the strongest OH Meinel emission lines in the (8–3, (5–1, (9–4, (8–4, and (6–2 vibrational bands. These coefficients are used to determine precise OH(8–3 rotational temperatures from spectra measured by the High Throughput Imaging Echelle Spectrograph (HiTIES, installed at the Kjell Henriksen Observatory (KHO, Svalbard. The method described in this paper also allows us to estimate atmospheric water vapour content using the HiTIES instrument.

  3. Characterisation and vapour sensing properties of spin coated thin films of anthracene labelled PMMA polymer

    Energy Technology Data Exchange (ETDEWEB)

    Capan, I., E-mail: inci.capan@gmail.com [Balikesir University, Faculty of Art and Sciences, Department of Physics, Cagis Campus, 10145 Balikesir (Turkey); Tarimci, C., E-mail: Celik.Tarimci@eng.ankara.edu.tr [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Ankara (Turkey); Erdogan, M., E-mail: merdogan@balikesir.edu.tr [Balikesir University, Faculty of Art and Sciences, Department of Physics, Cagis Campus, 10145 Balikesir (Turkey); Hassan, A.K., E-mail: A.Hassan@shu.ac.uk [Materials and Engineering Research Institute, Sheffield Hallam University, Sheaf Building, Pond Street, Sheffield S1 1WB (United Kingdom)

    2009-05-05

    In the present article thin films of poly (methyl methacrylate) (PMMA) polymer labelled with anthracene (Ant-PMMA) prepared by spin coating are characterised by UV-visible spectroscopy, surface plasmon resonance (SPR), spectroscopic ellipsometry (SE) and Atomic Force Microscopy (AFM) and their organic vapour sensing properties are investigated. Ant-PMMA films' thickness are determined by performing theoretical fitting to experimental data measured using SPR and SE. Results obtained show that the spin-cast films are of good uniformity with an average thickness of 6-8 nm. Organic vapour sensing properties are studied using SPR technique during exposures to different volatile organic compounds (VOCs). Ant-PMMA films' response to the selected VOCs has been examined in terms of solubility parameters and molar volumes of the solvents, and the films were found to be largely sensitive to benzene vapour compared to other studied analytes.

  4. Characterisation and vapour sensing properties of spin coated thin films of anthracene labelled PMMA polymer

    International Nuclear Information System (INIS)

    Capan, I.; Tarimci, C.; Erdogan, M.; Hassan, A.K.

    2009-01-01

    In the present article thin films of poly (methyl methacrylate) (PMMA) polymer labelled with anthracene (Ant-PMMA) prepared by spin coating are characterised by UV-visible spectroscopy, surface plasmon resonance (SPR), spectroscopic ellipsometry (SE) and Atomic Force Microscopy (AFM) and their organic vapour sensing properties are investigated. Ant-PMMA films' thickness are determined by performing theoretical fitting to experimental data measured using SPR and SE. Results obtained show that the spin-cast films are of good uniformity with an average thickness of 6-8 nm. Organic vapour sensing properties are studied using SPR technique during exposures to different volatile organic compounds (VOCs). Ant-PMMA films' response to the selected VOCs has been examined in terms of solubility parameters and molar volumes of the solvents, and the films were found to be largely sensitive to benzene vapour compared to other studied analytes.

  5. Evolution of polarization in an atomic vapour with negative refractive index

    International Nuclear Information System (INIS)

    Zhuang Fei; Shen Jianqi

    2006-01-01

    A three-level Lambda-configuration atomic vapour may exhibit simultaneously negative permittivity and permeability in the optical frequency band, and an isotropic left-handed vapour medium could therefore be realized within the framework of quantum optics. One of the most remarkable features of the present scheme is that both the refractive index and the photon helicity reversal inside the vapour can be controllably manipulated by an external coupling light field. The phenomenological Hamiltonian that describes the process of helicity reversal is constructed and the time-dependent Schroedinger equation governing the time evolution of the polarization states of the lightwave is solved by means of the Lewis-Riesenfeld invariant theory. The transition between the polarization states (and hence the accompanied photon helicity reversal), which is exactly analogous to the transition operation between bits in digital circuit, may be valuable for the development of new techniques in quantum optics and would have potential applications in information technology

  6. Distribution of tritium in water vapour and precipitation around Wolsung nuclear power plant.

    Science.gov (United States)

    Chae, Jung-Seok; Lee, Sang-Kuk; Kim, Yongjae; Lee, Jung-Min; Cho, Heung-Joon; Cho, Yong-Woo; Yun, Ju-Yong

    2011-07-01

    The distribution of tritium in water vapour and precipitation with discharge of tritiated water vapour and meteorological factors was studied around the Wolsung nuclear power plant (NPP) site during the period 2004-2008. The tritium concentrations in atmospheric water vapour and precipitation had a temporal variation with relatively high values in the early summer. Spatial distribution of tritium concentrations was affected by various factors such as distance from the NPP site, wind direction, tritium discharge into the atmosphere and atmospheric dispersion factor. The annual mean concentrations of atmospheric HTO and precipitation were correlated with the amount of gaseous tritium released from the Wolsung NPP. The tritium concentrations in precipitation decrease exponentially with an increase of the distance from the Wolsung NPP site.

  7. Measurement and modeling of high-pressure (vapour + liquid) equilibria of (CO2 + alcohol) binary systems

    International Nuclear Information System (INIS)

    Gutierrez, Jorge E.; Bejarano, Arturo; Fuente, Juan C. de la

    2010-01-01

    An apparatus based on a static-analytic method assembled in this work was utilized to perform high pressure (vapour + liquid) equilibria measurements with uncertainties estimated at 2 + 1-propanol), (CO 2 + 2-methyl-1-propanol), (CO 2 + 3-methyl-1-butanol), and (CO 2 + 1-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 12) MPa. For all the (CO 2 + alcohol) systems, it was visually monitored to insure that there was no liquid immiscibility at the temperatures and pressures studied. The experimental results were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapour + liquid) equilibria compositions were found to be in good agreement with the experimental values with deviations for the mol fractions <0.12 and <0.05 for the liquid and vapour phase, respectively.

  8. A novel polygeneration system integrating photovoltaic/thermal collectors, solar assisted heat pump, adsorption chiller and electrical energy storage: Dynamic and energy-economic analysis

    International Nuclear Information System (INIS)

    Calise, Francesco; Figaj, Rafal Damian; Vanoli, Laura

    2017-01-01

    Highlights: • Space heating/cooling, domestic hot water and electrical energy are provided by the system. • Two different users are investigated: fitness center and office. • The influence of the battery system on system economic performance is scarce. • Net metering contract is more profitable compared to simplified purchase/resale arrangement one. - Abstract: In this paper a dynamic simulation model and a thermo-economic analysis of a novel polygeneration system are presented. The system includes photovoltaic/thermal collectors coupled with a solar-assisted heat pump, an adsorption chiller and an electrical energy storage. The modelled plant supplies electrical energy, space heating and cooling and domestic hot water. The produced solar thermal energy is used during the winter to supply the heat pump evaporator, providing the required space heating. In summer, solar thermal energy is used to drive an adsorption chiller providing the required space cooling. All year long, solar thermal energy in excess, with respect to the space heating and cooling demand, is used to produce domestic hot water. The produced electrical energy is self-consumed by both user and system auxiliary equipment and/or supplied to the grid. The system model includes a detailed electrical energy model for user storage and exchange with the grid along with a detailed building model. This study is a continuation of previous works recently presented by the authors. In particular, the present paper focuses on the real electrical demands of several types of users and on the analysis of the comfort of building users. Differently from the works previously published by the authors, the present work bases the calculations on measured electrical demands of real users (fitness center and offices). The system performance is analyzed with two different electricity supply contracts: net metering and simplified purchase/resale arrangement. Daily, weekly and yearly results are presented. Finally, a

  9. Vapours of US and EU Market Leader Electronic Cigarette Brands and Liquids Are Cytotoxic for Human Vascular Endothelial Cells

    Science.gov (United States)

    Putzhammer, Raphaela; Doppler, Christian; Jakschitz, Thomas; Heinz, Katharina; Förste, Juliane; Danzl, Katarina; Messner, Barbara; Bernhard, David

    2016-01-01

    The present study was conducted to provide toxicological data on e-cigarette vapours of different e-cigarette brands and liquids from systems viewed as leaders in the e-cigarette market and to compare e-cigarette vapour toxicity to the toxicity of conventional strong high-nicotine cigarette smoke. Using an adapted version of a previously constructed cigarette smoke constituent sampling device, we collected the hydrophilic fraction of e-cigarette vapour and exposed human umbilical vein endothelial cells (HUVECs) to the mixture of compounds present in the vapour of 4 different single-use e-cigarettes, 6 different liquid vapours produced by the same refillable e-cigarette, and one e-cigarette with an exchangeable liquid cartridge. After incubation of cells with various concentrations and for various periods of time we analysed cell death induction, proliferation rates, the occurrence of intra-cellular reactive oxygen species, cell morphology, and we also measured e-cigarette heating coil temperatures. Overall, conventional cigarette smoke extract showed the most severe impact on endothelial cells. However, some e-cigarette vapour extracts showed high cytotoxicity, inhibition of cell proliferation, and alterations in cell morphology, which were comparable to conventional high-nicotine cigarettes. The vapours generated from different liquids using the same e-cigarette show substantial differences, pointing to the liquids as an important source for toxicity. E-cigarette vapour-mediated induction of oxidative stress was significant in one out of the 11 analysed vapours. There is a high variability in the acute cytotoxicity of e-cigarette vapours depending on the liquid and on the e-cigarettes used. Some products showed toxic effects close to a conventional high-nicotine cigarette. Liquid nicotine, menthol content, and the formation of acute intracellular reactive oxygen species do not seem to be the central elements in e-cigarette vapour toxicity. PMID:27351725

  10. Vapours of US and EU Market Leader Electronic Cigarette Brands and Liquids Are Cytotoxic for Human Vascular Endothelial Cells.

    Science.gov (United States)

    Putzhammer, Raphaela; Doppler, Christian; Jakschitz, Thomas; Heinz, Katharina; Förste, Juliane; Danzl, Katarina; Messner, Barbara; Bernhard, David

    2016-01-01

    The present study was conducted to provide toxicological data on e-cigarette vapours of different e-cigarette brands and liquids from systems viewed as leaders in the e-cigarette market and to compare e-cigarette vapour toxicity to the toxicity of conventional strong high-nicotine cigarette smoke. Using an adapted version of a previously constructed cigarette smoke constituent sampling device, we collected the hydrophilic fraction of e-cigarette vapour and exposed human umbilical vein endothelial cells (HUVECs) to the mixture of compounds present in the vapour of 4 different single-use e-cigarettes, 6 different liquid vapours produced by the same refillable e-cigarette, and one e-cigarette with an exchangeable liquid cartridge. After incubation of cells with various concentrations and for various periods of time we analysed cell death induction, proliferation rates, the occurrence of intra-cellular reactive oxygen species, cell morphology, and we also measured e-cigarette heating coil temperatures. Overall, conventional cigarette smoke extract showed the most severe impact on endothelial cells. However, some e-cigarette vapour extracts showed high cytotoxicity, inhibition of cell proliferation, and alterations in cell morphology, which were comparable to conventional high-nicotine cigarettes. The vapours generated from different liquids using the same e-cigarette show substantial differences, pointing to the liquids as an important source for toxicity. E-cigarette vapour-mediated induction of oxidative stress was significant in one out of the 11 analysed vapours. There is a high variability in the acute cytotoxicity of e-cigarette vapours depending on the liquid and on the e-cigarettes used. Some products showed toxic effects close to a conventional high-nicotine cigarette. Liquid nicotine, menthol content, and the formation of acute intracellular reactive oxygen species do not seem to be the central elements in e-cigarette vapour toxicity.

  11. Vapours of US and EU Market Leader Electronic Cigarette Brands and Liquids Are Cytotoxic for Human Vascular Endothelial Cells.

    Directory of Open Access Journals (Sweden)

    Raphaela Putzhammer

    Full Text Available The present study was conducted to provide toxicological data on e-cigarette vapours of different e-cigarette brands and liquids from systems viewed as leaders in the e-cigarette market and to compare e-cigarette vapour toxicity to the toxicity of conventional strong high-nicotine cigarette smoke. Using an adapted version of a previously constructed cigarette smoke constituent sampling device, we collected the hydrophilic fraction of e-cigarette vapour and exposed human umbilical vein endothelial cells (HUVECs to the mixture of compounds present in the vapour of 4 different single-use e-cigarettes, 6 different liquid vapours produced by the same refillable e-cigarette, and one e-cigarette with an exchangeable liquid cartridge. After incubation of cells with various concentrations and for various periods of time we analysed cell death induction, proliferation rates, the occurrence of intra-cellular reactive oxygen species, cell morphology, and we also measured e-cigarette heating coil temperatures. Overall, conventional cigarette smoke extract showed the most severe impact on endothelial cells. However, some e-cigarette vapour extracts showed high cytotoxicity, inhibition of cell proliferation, and alterations in cell morphology, which were comparable to conventional high-nicotine cigarettes. The vapours generated from different liquids using the same e-cigarette show substantial differences, pointing to the liquids as an important source for toxicity. E-cigarette vapour-mediated induction of oxidative stress was significant in one out of the 11 analysed vapours. There is a high variability in the acute cytotoxicity of e-cigarette vapours depending on the liquid and on the e-cigarettes used. Some products showed toxic effects close to a conventional high-nicotine cigarette. Liquid nicotine, menthol content, and the formation of acute intracellular reactive oxygen species do not seem to be the central elements in e-cigarette vapour toxicity.

  12. Intercomparison of atmospheric water vapour measurements at a Canadian High Arctic site

    Science.gov (United States)

    Weaver, Dan; Strong, Kimberly; Schneider, Matthias; Rowe, Penny M.; Sioris, Chris; Walker, Kaley A.; Mariani, Zen; Uttal, Taneil; McElroy, C. Thomas; Vömel, Holger; Spassiani, Alessio; Drummond, James R.

    2017-08-01

    Water vapour is a critical component of the Earth system. Techniques to acquire and improve measurements of atmospheric water vapour and its isotopes are under active development. This work presents a detailed intercomparison of water vapour total column measurements taken between 2006 and 2014 at a Canadian High Arctic research site (Eureka, Nunavut). Instruments include radiosondes, sun photometers, a microwave radiometer, and emission and solar absorption Fourier transform infrared (FTIR) spectrometers. Close agreement is observed between all combination of datasets, with mean differences ≤ 1.0 kg m-2 and correlation coefficients ≥ 0.98. The one exception in the observed high correlation is the comparison between the microwave radiometer and a radiosonde product, which had a correlation coefficient of 0.92.A variety of biases affecting Eureka instruments are revealed and discussed. A subset of Eureka radiosonde measurements was processed by the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) for this study. Comparisons reveal a small dry bias in the standard radiosonde measurement water vapour total columns of approximately 4 %. A recently produced solar absorption FTIR spectrometer dataset resulting from the MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) retrieval technique is shown to offer accurate measurements of water vapour total columns (e.g. average agreement within -5.2 % of GRUAN and -6.5 % of a co-located emission FTIR spectrometer). However, comparisons show a small wet bias of approximately 6 % at the high-latitude Eureka site. In addition, a new dataset derived from Atmospheric Emitted Radiance Interferometer (AERI) measurements is shown to provide accurate water vapour measurements (e.g. average agreement was within 4 % of GRUAN), which usefully enables measurements to be taken during day and night (especially valuable during polar night).

  13. Theoretical calculations of primary particle condensation for cadmium and caesium iodide vapours

    Energy Technology Data Exchange (ETDEWEB)

    Buckle, E.R. [Division of Metallurgy, School of Materials, The University, Mappin Street, Sheffield S1 3JD (United Kingdom); Bowsher, B.R. [Chemistry Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

    1988-10-15

    A theoretical approach to modelling aerosol nucleation from the vapour phase has been developed by Buckle. In this theory, the condensing vapour species are assumed to be transported from an evaporating source across a one-dimensional stagnant boundary layer into an unreactive vapour-free atmosphere. A slip-flow model for interfacial energy and mass flow is combined with this stagnant boundary layer model to yield a set of parameters that uniquely characterise the evaporative flow process (i.e. pressure, source and sink temperatures, sink concentration, and the flux density of heat or mass from the source). To obtain the initial conditions for nucleation the vapour saturation ratio p/p deg is plotted against temperature and compared with the minimum saturation ratio defined by homogeneous nucleation theory. The co-education be represented by a nucleation threshold (or F) diagram. The mass and energy equations of the flow are solved by introducing the Becker-Doering formula for the nucleation rate, and the Stefan diffusion model for particle growth. This gives the rise and fall of supersaturation and the evolution of the particle size distribution along the flow coordinate. In the present studies, the applicability of the model has been tested by considering the condensation of caesium iodide and cadmium vapours under a wide variety of pre-mixed flow conditions of interest to PWR severe accident studies. The model has been used to predict the onset of nucleation and the particle size distribution for single vapour species. Preliminary studies have demonstrated that conditions exist whereby both heterogeneous and homogeneous nucleation can occur simultaneously. This process could account for experimental observations of chemically-different aerosols being formed under severe reactor accident conditions. (author)

  14. Different physiological and behavioural effects of e-cigarette vapour and cigarette smoke in mice.

    Science.gov (United States)

    Ponzoni, L; Moretti, M; Sala, M; Fasoli, F; Mucchietto, V; Lucini, V; Cannazza, G; Gallesi, G; Castellana, C N; Clementi, F; Zoli, M; Gotti, C; Braida, D

    2015-10-01

    Nicotine is the primary addictive substance in tobacco smoke and electronic cigarette (e-cig) vapour. Methodological limitations have made it difficult to compare the role of the nicotine and non-nicotine constituents of tobacco smoke. The aim of this study was to compare the effects of traditional cigarette smoke and e-cig vapour containing the same amount of nicotine in male BALB/c mice exposed to the smoke of 21 cigarettes or e-cig vapour containing 16.8 mg of nicotine delivered by means of a mechanical ventilator for three 30-min sessions/day for seven weeks. One hour after the last session, half of the animals were sacrificed for neurochemical analysis, and the others underwent mecamylamine-precipitated or spontaneous withdrawal for the purposes of behavioural analysis. Chronic intermittent non-contingent, second-hand exposure to cigarette smoke or e-cig vapour led to similar brain cotinine and nicotine levels, similar urine cotinine levels and the similar up-regulation of α4β2 nicotinic acetylcholine receptors in different brain areas, but had different effects on body weight, food intake, and the signs of mecamylamine-precipitated and spontaneous withdrawal episodic memory and emotional responses. The findings of this study demonstrate for the first time that e-cig vapour induces addiction-related neurochemical, physiological and behavioural alterations. The fact that inhaled cigarette smoke and e-cig vapour have partially different dependence-related effects indicates that compounds other than nicotine contribute to tobacco dependence. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  15. WATER VAPOUR PERMEABILITY PROPERTIES OF CELLULAR WOOD MATERIAL AND CONDENSATION RISK OF COMPOSITE PANEL WALLS

    Directory of Open Access Journals (Sweden)

    Janis IEJAVS

    2016-09-01

    Full Text Available Invention of light weight cellular wood material (CWM with a trade mark of Dendrolight is one of innovations in wood industry of the last decade. The aim of the research was to define the water vapour permeability properties of CWM and to analyse the condensation risk of various wall envelopes where solid wood cellular material is used. To determine the water vapour permeability of CWM, test samples were produced in the factory using routine production technology and tested according to the standard EN 12086:2014. Water vapour permeability factor (μ and other properties of six different configurations of CWM samples were determined. Using the experimental data the indicative influence of geometrical parameters such as lamella thickness, number of lamellas and material direction were investigated and evaluated. To study the condensation risk within the wall envelope containing CWM calculation method given in LVS EN ISO 13788:2012 was used. To ease the calculation process previously developed JavaScript calculation software that had only capability to calculate thermal transmittance was extended so that condensation risk in multi-layer composite walls can be analysed. Water vapour permeability factor in CWM is highly direction dependant. If parallel and perpendicular direction of CWM is compared the value of water vapour permeability factor can differentiate more than two times. Another significant factor for condensation risk analysis is overall thickness of CWM since it directly influences the equivalent air layer thickness. The influence of other factors such as lamella thickness, or groove depth is minor when water vapour permeability properties are compared. From the analysis of CWM performance in building envelope it can be concluded that uninsulated CWM panels used during winter months will pose the risk of condensation damage to structure, but the risk can be reduced or prevented if insulation layer is applied to the CWM panel wall

  16. Microstructural development in physical vapour-deposited partially stabilized zirconia thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Y. H. (Center for Intelligent Processing of Materials, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609-2280 (United States)); Biederman, R.R. (Center for Intelligent Processing of Materials, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609-2280 (United States)); Sisson, R.D. Jr. (Center for Intelligent Processing of Materials, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609-2280 (United States))

    1994-10-01

    The effects of processing parameters of physical vapour deposition on the microstructure of partially stabilized zirconia (PSZ) thermal barrier coatings have been experimentally investigated. Emphasis has been placed on the crystallographic texture of the PSZ coatings and the microstructure of the top surface of the PSZ coatings as well as the metal-ceramic interface. The variations in the deposition chamber temperature, substrate thickness, substrate rotation and vapour incidence angle resulted in the observation of significant differences in the crystallographic texture and microstructure of the PSZ coatings. ((orig.))

  17. SPATIO-TEMPORAL ESTIMATION OF INTEGRATED WATER VAPOUR OVER THE MALAYSIAN PENINSULA DURING MONSOON SEASON

    Directory of Open Access Journals (Sweden)

    S. Salihin

    2017-10-01

    Full Text Available This paper provides the precise information on spatial-temporal distribution of water vapour that was retrieved from Zenith Path Delay (ZPD which was estimated by Global Positioning System (GPS processing over the Malaysian Peninsular. A time series analysis of these ZPD and Integrated Water Vapor (IWV values was done to capture the characteristic on their seasonal variation during monsoon seasons. This study was found that the pattern and distribution of atmospheric water vapour over Malaysian Peninsular in whole four years periods were influenced by two inter-monsoon and two monsoon seasons which are First Inter-monsoon, Second Inter-monsoon, Southwest monsoon and Northeast monsoon.

  18. Vapour pressures and heat capacity measurements on the C7-C9 secondary aliphatic alcohols

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Schick, Christoph

    2007-01-01

    Molar enthalpies of vaporization of secondary C 7 -C 9 alkanols were obtained from the temperature dependence of the vapour pressure measured by the transpiration method. The measured data sets were checked for internal consistency successfully. A large number of the primary experimental results on temperature dependences of vapour pressures of secondary alcohols have been collected from the literature and have been treated uniform in order to derive their vaporization enthalpies at the reference temperature 298.15 K. This collection, together with our experimental results, have helped to ascertain the database for branched aliphatic alcohols

  19. Effect of slow-solvent-vapour treatment on performance of polymer photovoltaic devices

    International Nuclear Information System (INIS)

    Zhi-Hui, Feng; Yan-Bing, Hou; Quan-Min, Shi; Xiao-Jun, Liu; Feng, Teng

    2010-01-01

    In this work, enhanced poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) bulkheterojunction photovoltaic devices are achieved via slow-solvent-vapour treatment. The correlations between the morphology of the active layer and the photovoltaic performance of polymer-based solar cell are investigated. The active layers are characterized by atomic force microscopy and optical absorption. The results show that slow-solvent-vapour treatment can induce P3HT self-organization into an ordered structure, leading to the enhanced absorption and efficient charge transport. (cross-disciplinary physics and related areas of science and technology)

  20. Introducing zinc cations into zeolite Y via the reduction of HY with zinc metal vapour

    Science.gov (United States)

    Seidel, A.; Boddenberg, B.

    1996-01-01

    Zeolites HY and NaY which were contacted with zinc metal vapour at 420°C were investigated by carbon monoxide and xenon adsorption as well as 129Xe NMR spectroscopy. The reaction of zeolite HY results in the incorporation of Zn 2+ cations which are shown to populate the supercage positions S II and S III to an unusually high extent. The supercage zinc cation concentration strongly decreases when the material is saturated with water and subsequently dehydrated at 400°C. The zeolite NaY turns out to be inert towards the reaction with zinc metal vapour.

  1. Thermal diffusion of water vapour in porous materials: fact or fiction?

    DEFF Research Database (Denmark)

    Janssen, Hans

    2011-01-01

    diffusion. Thermal diffusion opponents, on the other hand, assert that these thermal transports are negligibly small. This paper resolves that contradiction. A critical analysis of the investigations supporting the occurrence of thermal diffusion reveals that all are flawed. A correct reinterpretation...... its negligible magnitude. It can in conclusion be stated that thermal diffusion is of no importance for building science applications, leaving vapour pressure as the sole significant transport potential for the diffusion of water vapour in porous materials. (C) 2010 Elsevier Ltd. All rights reserved....

  2. Microwave measurements of the absolute values of absorption by water vapour in the atmosphere.

    Science.gov (United States)

    Hogg, D C; Guiraud, F O

    1979-05-31

    MEASUREMENT of the absolute value of absorption by water vapour at microwave frequencies is difficult because the effect is so small. Far in the wings of the absorption lines, in the so-called 'windows' of the spectrum, it is especially difficult to achieve high accuracy in the free atmosphere. But it is in these windows that the behaviour of the absorption is important from both applied and scientific points of view. Satellite communications, remote sensing of the atmosphere, and radioastronomy, are all influenced by this behaviour. Measurements on an Earth-space path are reported here; the results indicate a nonlinear relationship between absorption and water-vapour content.

  3. A simple passive method of collecting water vapour for environmental tritium monitoring

    International Nuclear Information System (INIS)

    Iida, T.; Fukuda, H.; Ikebe, Y.; Yokoyama, S.

    1995-01-01

    To investigate the average behaviour of tritium in an atmospheric environment, it is necessary to collect water vapour in air over a long period at numerous locations. For the purpose of the study, the passive method was developed: this is handy, low-priced and could collect water vapour in air without motive power. This paper describes the characteristics of the passive collecting method, the performance of water collection in outdoor air and the measurements of tritium concentrations in water samples collected by the passive method. (author)

  4. Low temperature absorption chiller - Report from a project in the programs Climate 21 and 'More efficient refrigeration and heat pump systems. Final report; Laagtemperaturdriven absorptionskylmaskin - Rapport oever ett projekt inom programmen Klimat 21 och Effektivare Kyl- och Vaermepumpssystem. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    Fredrik Setterwall [Fredrik Setterwall Konsult AB, Sollentuna (Sweden); Andersson, Mikael [AB Berglunds Rostfria, Boden (Sweden); Glebov, Dmitrey; Martin, Viktoria [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Chemical Technology

    2005-06-01

    An absorption chiller with a 1.15 MW cooling effect has been designed in a collaboration project comprising university, industry and end-user. This chiller is designed to run on district heating (70-90 deg C), and its layout and function differs from conventional absorption chillers as outlined below. The chiller's heat transfer surfaces may be installed horizontally or vertically, resulting in flexibility in system design. In a conventional absorption chiller, these surfaces are always horizontally aligned. The high-pressure and low-pressure parts of the chiller may be placed independently of each other. In a conventional chiller, the high-pressure part must always be placed on top of the low-pressure part. To enable the flexibility in design and system layout, this chiller is equipped with four internal pumps instead of only two in conventional design. The increased number of pumps leads to an increase of the installed electrical power for internal pumps. The electrical power for the internal pumps is however only a small fraction of the totally installed electrical power. The main part is utilized for pumping of cooling water and coolant. This low temperature driven, single-effect chiller has a high coefficient of performance (COP). The 'first generation machine' installed at Chalmers University of Technology has a COP equal to 0.75 at full load. Through the control strategy used, the chiller can maintain a high COP even at part load. Because of the high COP, the electricity consumption of the cooling water pump is kept low. To lower the size of the absorber and generator, the chiller is equipped with extra plate heat exchangers to cool the strong solution before the absorber, and preheat the weak solution before the generator. To increase the heat transfer rate, a new additive (2-methyl-penthanol) has been tested. As compared to the conventional heat transfer additive (2-ethyl-hexanol), the heat transfer enhancement was 20% higher with the new

  5. Compressive Transient Imaging

    KAUST Repository

    Sun, Qilin

    2017-04-01

    High resolution transient/3D imaging technology is of high interest in both scientific research and commercial application. Nowadays, all of the transient imaging methods suffer from low resolution or time consuming mechanical scanning. We proposed a new method based on TCSPC and Compressive Sensing to achieve a high resolution transient imaging with a several seconds capturing process. Picosecond laser sends a serious of equal interval pulse while synchronized SPAD camera\\'s detecting gate window has a precise phase delay at each cycle. After capturing enough points, we are able to make up a whole signal. By inserting a DMD device into the system, we are able to modulate all the frames of data using binary random patterns to reconstruct a super resolution transient/3D image later. Because the low fill factor of SPAD sensor will make a compressive sensing scenario ill-conditioned, We designed and fabricated a diffractive microlens array. We proposed a new CS reconstruction algorithm which is able to denoise at the same time for the measurements suffering from Poisson noise. Instead of a single SPAD senor, we chose a SPAD array because it can drastically reduce the requirement for the number of measurements and its reconstruction time. Further more, it not easy to reconstruct a high resolution image with only one single sensor while for an array, it just needs to reconstruct small patches and a few measurements. In this thesis, we evaluated the reconstruction methods using both clean measurements and the version corrupted by Poisson noise. The results show how the integration over the layers influence the image quality and our algorithm works well while the measurements suffer from non-trival Poisson noise. It\\'s a breakthrough in the areas of both transient imaging and compressive sensing.

  6. Fast Compressive Tracking.

    Science.gov (United States)

    Zhang, Kaihua; Zhang, Lei; Yang, Ming-Hsuan

    2014-10-01

    It is a challenging task to develop effective and efficient appearance models for robust object tracking due to factors such as pose variation, illumination change, occlusion, and motion blur. Existing online tracking algorithms often update models with samples from observations in recent frames. Despite much success has been demonstrated, numerous issues remain to be addressed. First, while these adaptive appearance models are data-dependent, there does not exist sufficient amount of data for online algorithms to learn at the outset. Second, online tracking algorithms often encounter the drift problems. As a result of self-taught learning, misaligned samples are likely to be added and degrade the appearance models. In this paper, we propose a simple yet effective and efficient tracking algorithm with an appearance model based on features extracted from a multiscale image feature space with data-independent basis. The proposed appearance model employs non-adaptive random projections that preserve the structure of the image feature space of objects. A very sparse measurement matrix is constructed to efficiently extract the features for the appearance model. We compress sample images of the foreground target and the background using the same sparse measurement matrix. The tracking task is formulated as a binary classification via a naive Bayes classifier with online update in the compressed domain. A coarse-to-fine search strategy is adopted to further reduce the computational complexity in the detection procedure. The proposed compressive tracking algorithm runs in real-time and performs favorably against state-of-the-art methods on challenging sequences in terms of efficiency, accuracy and robustness.

  7. SeqCompress: an algorithm for biological sequence compression.

    Science.gov (United States)

    Sardaraz, Muhammad; Tahir, Muhammad; Ikram, Ataul Aziz; Bajwa, Hassan

    2014-10-01

    The growth of Next Generation Sequencing technologies presents significant research challenges, specifically to design bioinformatics tools that handle massive amount of data efficiently. Biological sequence data storage cost has become a noticeable proportion of total cost in the generation and analysis. Particularly increase in DNA sequencing rate is significantly outstripping the rate of increase in disk storage capacity, which may go beyond the limit of storage capacity. It is essential to develop algorithms that handle large data sets via better memory management. This article presents a DNA sequence compression algorithm SeqCompress that copes with the space complexity of biological sequences. The algorithm is based on lossless data compression and uses statistical model as well as arithmetic coding to compress DNA sequences. The proposed algorithm is compared with recent specialized compression tools for biological sequences. Experimental results show that proposed algorithm has better compression gain as compared to other existing algorithms. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Comparative data compression techniques and multi-compression results

    International Nuclear Information System (INIS)

    Hasan, M R; Ibrahimy, M I; Motakabber, S M A; Ferdaus, M M; Khan, M N H

    2013-01-01

    Data compression is very necessary in business data processing, because of the cost savings that it offers and the large volume of data manipulated in many business applications. It is a method or system for transmitting a digital image (i.e., an array of pixels) from a digital data source to a digital data receiver. More the size of the data be smaller, it provides better transmission speed and saves time. In this communication, we always want to transmit data efficiently and noise freely. This paper will provide some compression techniques for lossless text type data compression and comparative result of multiple and single compression, that will help to find out better compression output and to develop compression algorithms

  9. Analysis by compression

    DEFF Research Database (Denmark)

    Meredith, David

    MEL is a geometric music encoding language designed to allow for musical objects to be encoded parsimoniously as sets of points in pitch-time space, generated by performing geometric transformations on component patterns. MEL has been implemented in Java and coupled with the SIATEC pattern...... discovery algorithm to allow for compact encodings to be generated automatically from in extenso note lists. The MEL-SIATEC system is founded on the belief that music analysis and music perception can be modelled as the compression of in extenso descriptions of musical objects....

  10. Compressive Fatigue in Wood

    DEFF Research Database (Denmark)

    Clorius, Christian Odin; Pedersen, Martin Bo Uhre; Hoffmeyer, Preben

    1999-01-01

    An investigation of fatigue failure in wood subjected to load cycles in compression parallel to grain is presented. Small clear specimens of spruce are taken to failure in square wave formed fatigue loading at a stress excitation level corresponding to 80% of the short term strength. Four...... frequencies ranging from 0.01 Hz to 10 Hz are used. The number of cycles to failure is found to be a poor measure of the fatigue performance of wood. Creep, maximum strain, stiffness and work are monitored throughout the fatigue tests. Accumulated creep is suggested identified with damage and a correlation...

  11. Compressive full waveform lidar

    Science.gov (United States)

    Yang, Weiyi; Ke, Jun

    2017-05-01

    To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.

  12. Metal Hydride Compression

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Terry A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bowman, Robert [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Smith, Barton [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Anovitz, Lawrence [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jensen, Craig [Hawaii Hydrogen Carriers LLC, Honolulu, HI (United States)

    2017-07-01

    Conventional hydrogen compressors often contribute over half of the cost of hydrogen stations, have poor reliability, and have insufficient flow rates for a mature FCEV market. Fatigue associated with their moving parts including cracking of diaphragms and failure of seal leads to failure in conventional compressors, which is exacerbated by the repeated starts and stops expected at fueling stations. Furthermore, the conventional lubrication of these compressors with oil is generally unacceptable at fueling stations due to potential fuel contamination. Metal hydride (MH) technology offers a very good alternative to both conventional (mechanical) and newly developed (electrochemical, ionic liquid pistons) methods of hydrogen compression. Advantages of MH compression include simplicity in design and operation, absence of moving parts, compactness, safety and reliability, and the possibility to utilize waste industrial heat to power the compressor. Beyond conventional H2 supplies of pipelines or tanker trucks, another attractive scenario is the on-site generating, pressuring and delivering pure H2 at pressure (≥ 875 bar) for refueling vehicles at electrolysis, wind, or solar generating production facilities in distributed locations that are too remote or widely distributed for cost effective bulk transport. MH hydrogen compression utilizes a reversible heat-driven interaction of a hydride-forming metal alloy with hydrogen gas to form the MH phase and is a promising process for hydrogen energy applications [1,2]. To deliver hydrogen continuously, each stage of the compressor must consist of multiple MH beds with synchronized hydrogenation & dehydrogenation cycles. Multistage pressurization allows achievement of greater compression ratios using reduced temperature swings compared to single stage compressors. The objectives of this project are to investigate and demonstrate on a laboratory scale a two-stage MH hydrogen (H2) gas compressor with a

  13. Methods for Sampling and Measurement of Compressed Air Contaminants

    International Nuclear Information System (INIS)

    Stroem, L.

    1976-10-01

    In order to improve the technique for measuring oil and water entrained in a compressed air stream, a laboratory study has been made of some methods for sampling and measurement. For this purpose water or oil as artificial contaminants were injected in thin streams into a test loop, carrying dry compressed air. Sampling was performed in a vertical run, down-stream of the injection point. Wall attached liquid, coarse droplet flow, and fine droplet flow were sampled separately. The results were compared with two-phase flow theory and direct observation of liquid behaviour. In a study of sample transport through narrow tubes, it was observed that, below a certain liquid loading, the sample did not move, the liquid remaining stationary on the tubing wall. The basic analysis of the collected samples was made by gravimetric methods. Adsorption tubes were used with success to measure water vapour. A humidity meter with a sensor of the aluminium oxide type was found to be unreliable. Oil could be measured selectively by a flame ionization detector, the sample being pretreated in an evaporation- condensation unit

  14. Methods for Sampling and Measurement of Compressed Air Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Stroem, L

    1976-10-15

    In order to improve the technique for measuring oil and water entrained in a compressed air stream, a laboratory study has been made of some methods for sampling and measurement. For this purpose water or oil as artificial contaminants were injected in thin streams into a test loop, carrying dry compressed air. Sampling was performed in a vertical run, down-stream of the injection point. Wall attached liquid, coarse droplet flow, and fine droplet flow were sampled separately. The results were compared with two-phase flow theory and direct observation of liquid behaviour. In a study of sample transport through narrow tubes, it was observed that, below a certain liquid loading, the sample did not move, the liquid remaining stationary on the tubing wall. The basic analysis of the collected samples was made by gravimetric methods. Adsorption tubes were used with success to measure water vapour. A humidity meter with a sensor of the aluminium oxide type was found to be unreliable. Oil could be measured selectively by a flame ionization detector, the sample being pretreated in an evaporation- condensation unit

  15. Film boiling heat transfer and vapour film collapse for various geometries

    International Nuclear Information System (INIS)

    Jouhara, H.I.; Axcell, B.P.

    2005-01-01

    Full text of publication follows: Film boiling heat transfer has application to the safe operation of water-cooled nuclear reactors under fault conditions and it has been studied using nickel-plated copper specimens in transient and steady state experiments. In the transient tests the specimens were held in a water flow; in the steady state investigation a specimen was mounted in an essentially quiescent pool of water. The transient investigation was conducted on two spheres with different diameters, two cylindrical specimens of different lengths in parallel flow, a short cylinder in cross flow and two flat plates with different lengths. The heat transfer coefficient, vapour film thickness (which was estimated from the heat transfer coefficient) and heat flux followed a similar behaviour with changing experimental conditions for all specimens studied. The heat transfer coefficient increased and the vapour film thickness and heat flux decreased as the specimen temperature decreased. As the water subcooling increased the heat transfer coefficient and the heat flux increased while the vapour film thickness decreased. The water velocity was found to have little influence on the film boiling heat transfer results except for the short cylinder in cross flow. The sphere diameter was found to affect the heat transfer results; the heat transfer coefficient and the heat flux were larger, for the larger sphere. No significant effect of the cylinder length on the heat transfer data was observed. However, the heat transfer coefficient was higher (and the average vapour film thinner) for the longer plate than for the shorter plate. Three vapour/liquid interface types were observed namely: 'smooth', 'rippled' and 'turbulent' depending largely on specimen and water temperatures. For all specimens, the maximum heat transfer coefficient, minimum heat flux and minimum film boiling temperature, occurring just before vapour film collapse, were found to increase as the water subcooling

  16. The vapour pressures over saturated aqueous solutions of cadmium chloride, cadmium bromide, cadmium iodide, cadmium nitrate, and cadmium sulphate

    International Nuclear Information System (INIS)

    Apelblat, Alexander; Korin, Eli

    2007-01-01

    Vapour pressures of water over saturated solutions of cadmium salts (chloride, bromide, iodide, nitrate, and sulphate) were determined over the temperature range 280 K to 322 K and compared with the literature data. The vapour pressures determined were used to obtain the water activities, osmotic coefficients and the molar enthalpies of vaporization in the (cadmium salt + water) systems

  17. The vapour pressures over saturated aqueous solutions of cadmium chloride, cadmium bromide, cadmium iodide, cadmium nitrate, and cadmium sulphate

    Energy Technology Data Exchange (ETDEWEB)

    Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel)]. E-mail: apelblat@bgu.ac.il; Korin, Eli [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel)

    2007-07-15

    Vapour pressures of water over saturated solutions of cadmium salts (chloride, bromide, iodide, nitrate, and sulphate) were determined over the temperature range 280 K to 322 K and compared with the literature data. The vapour pressures determined were used to obtain the water activities, osmotic coefficients and the molar enthalpies of vaporization in the (cadmium salt + water) systems.

  18. Determination of material constants of vertically aligned carbon nanotube structures in compressions

    International Nuclear Information System (INIS)

    Li, Yupeng; Kang, Junmo; Choi, Jae-Boong; Nam, Jae-Do; Suhr, Jonghwan

    2015-01-01

    Different chemical vapour deposition (CVD) fabrication conditions lead to a wide range of variation in the microstructure and morphologies of carbon nanotubes (CNTs), which actually determine the compressive mechanical properties of CNTs. However, the underlying relationship between the structure/morphology and mechanical properties of CNTs is not fully understood. In this study, we characterized and compared the structural and morphological properties of three kinds of vertically aligned carbon nanotube (VACNT) arrays from different CVD fabrication methods and performed monotonic compressive tests for each VACNT array. The compressive stress–strain responses and plastic deformation were first compared and analyzed with nanotube buckling behaviours. To quantify the compressive properties of the VACNT arrays, a strain density energy function was used to determine their intrinsic material constants. Then, the structural and morphological effects on the quantified material constants of the VACNTs were statistically investigated and analogized to cellular materials with an open-cell model. The statistical analysis shows that density, defect degree, and the moment of inertia of the CNTs are key factors in the improvement of the compressive mechanical properties of VACNT arrays. This approach could allow a model-driven CNT synthesis for engineering their mechanical behaviours. (paper)

  19. Free compression tube. Applications

    Science.gov (United States)

    Rusu, Ioan

    2012-11-01

    During the flight of vehicles, their propulsion energy must overcome gravity, to ensure the displacement of air masses on vehicle trajectory, to cover both energy losses from the friction between a solid surface and the air and also the kinetic energy of reflected air masses due to the impact with the flying vehicle. The flight optimization by increasing speed and reducing fuel consumption has directed research in the aerodynamics field. The flying vehicles shapes obtained through studies in the wind tunnel provide the optimization of the impact with the air masses and the airflow along the vehicle. By energy balance studies for vehicles in flight, the author Ioan Rusu directed his research in reducing the energy lost at vehicle impact with air masses. In this respect as compared to classical solutions for building flight vehicles aerodynamic surfaces which reduce the impact and friction with air masses, Ioan Rusu has invented a device which he named free compression tube for rockets, registered with the State Office for Inventions and Trademarks of Romania, OSIM, deposit f 2011 0352. Mounted in front of flight vehicles it eliminates significantly the impact and friction of air masses with the vehicle solid. The air masses come into contact with the air inside the free compression tube and the air-solid friction is eliminated and replaced by air to air friction.

  20. Photon compression in cylinders

    International Nuclear Information System (INIS)

    Ensley, D.L.

    1977-01-01

    It has been shown theoretically that intense microwave radiation is absorbed non-classically by a newly enunciated mechanism when interacting with hydrogen plasma. Fields > 1 Mg, lambda > 1 mm are within this regime. The predicted absorption, approximately P/sub rf/v/sub theta/sup e/, has not yet been experimentally confirmed. The applications of such a coupling are many. If microwave bursts approximately > 5 x 10 14 watts, 5 ns can be generated, the net generation of power from pellet fusion as well as various military applications becomes feasible. The purpose, then, for considering gas-gun photon compression is to obtain the above experimental capability by converting the gas kinetic energy directly into microwave form. Energies of >10 5 joules cm -2 and powers of >10 13 watts cm -2 are potentially available for photon interaction experiments using presently available technology. The following topics are discussed: microwave modes in a finite cylinder, injection, compression, switchout operation, and system performance parameter scaling

  1. Fingerprints in Compressed Strings

    DEFF Research Database (Denmark)

    Bille, Philip; Cording, Patrick Hagge; Gørtz, Inge Li

    2013-01-01

    The Karp-Rabin fingerprint of a string is a type of hash value that due to its strong properties has been used in many string algorithms. In this paper we show how to construct a data structure for a string S of size N compressed by a context-free grammar of size n that answers fingerprint queries...... derivative that captures LZ78 compression and its variations) we get O(loglogN) query time. Hence, our data structures has the same time and space complexity as for random access in SLPs. We utilize the fingerprint data structures to solve the longest common extension problem in query time O(logNlogℓ) and O....... That is, given indices i and j, the answer to a query is the fingerprint of the substring S[i,j]. We present the first O(n) space data structures that answer fingerprint queries without decompressing any characters. For Straight Line Programs (SLP) we get O(logN) query time, and for Linear SLPs (an SLP...

  2. Air conditioning using an air-cooled single effect lithium bromide absorption chiller: Results of a trial conducted in Madrid in August 2005

    International Nuclear Information System (INIS)

    Izquierdo, M.; Lizarte, R.; Marcos, J.D.; Gutierrez, G.

    2008-01-01

    Trials were conducted to determine the performance of a commercial (Rotartica 045v) 4.5-kW air-cooled, single effect LiBr/H 2 O absorption chiller for residential use. The experiments were run at La Poveda, Arganda del Rey, Madrid, in August 2005. Three typical August days, with different outdoor temperatures, were chosen for the study. The hot water inlet temperature in the generator varied throughout the day from 80 to 107 o C. Thermal demand was calculated, along with period energy balance and COP. Variations in machine component temperatures were recorded and chilling power and the daily COP calculated for each of the three days. The results for the period as a whole showed that cooling power tended to decline with rising outdoor dry bulb temperatures. At temperatures from 35 to 41.3 o C the chilled water outlet temperature in the evaporator climbed to over 15 o C. The average COP for the period, when auxiliary equipment was included into the calculations, was 0.37

  3. Compressive sensing in medical imaging.

    Science.gov (United States)

    Graff, Christian G; Sidky, Emil Y

    2015-03-10

    The promise of compressive sensing, exploitation of compressibility to achieve high quality image reconstructions with less data, has attracted a great deal of attention in the medical imaging community. At the Compressed Sensing Incubator meeting held in April 2014 at OSA Headquarters in Washington, DC, presentations were given summarizing some of the research efforts ongoing in compressive sensing for x-ray computed tomography and magnetic resonance imaging systems. This article provides an expanded version of these presentations. Sparsity-exploiting reconstruction algorithms that have gained popularity in the medical imaging community are studied, and examples of clinical applications that could benefit from compressive sensing ideas are provided. The current and potential future impact of compressive sensing on the medical imaging field is discussed.

  4. Generalized massive optimal data compression

    Science.gov (United States)

    Alsing, Justin; Wandelt, Benjamin

    2018-05-01

    In this paper, we provide a general procedure for optimally compressing N data down to n summary statistics, where n is equal to the number of parameters of interest. We show that compression to the score function - the gradient of the log-likelihood with respect to the parameters - yields n compressed statistics that are optimal in the sense that they preserve the Fisher information content of the data. Our method generalizes earlier work on linear Karhunen-Loéve compression for Gaussian data whilst recovering both lossless linear compression and quadratic estimation as special cases when they are optimal. We give a unified treatment that also includes the general non-Gaussian case as long as mild regularity conditions are satisfied, producing optimal non-linear summary statistics when appropriate. As a worked example, we derive explicitly the n optimal compressed statistics for Gaussian data in the general case where both the mean and covariance depend on the parameters.

  5. Leidenfrost vapour layer moderation of the drag crisis and trajectories of superhydrophobic and hydrophilic spheres falling in water

    KAUST Repository

    Vakarelski, Ivan Uriev; Chan, Derek Y C; Thoroddsen, Sigurdur T

    2014-01-01

    We investigate the dynamic effects of a Leidenfrost vapour layer sustained on the surface of heated steel spheres during free fall in water. We find that a stable vapour layer sustained on the textured superhydrophobic surface of spheres falling through 95 °C water can reduce the hydrodynamic drag by up to 75% and stabilize the sphere trajectory for the Reynolds number between 104 and 106, spanning the drag crisis in the absence of the vapour layer. For hydrophilic spheres under the same conditions, the transition to drag reduction and trajectory stability occurs abruptly at a temperature different from the static Leidenfrost point. The observed drag reduction effects are attributed to the disruption of the viscous boundary layer by the vapour layer whose thickness depends on the water temperature. Both the drag reduction and the trajectory stabilization effects are expected to have significant implications for development of sustainable vapour layer based technologies. © the Partner Organisations 2014.

  6. The Use of VMD Data/Model to Test Different Thermodynamic Models for Vapour-Liquid Equilibrium

    DEFF Research Database (Denmark)

    Abildskov, Jens; Azquierdo-Gil, M.A.; Jonsson, Gunnar Eigil

    2004-01-01

    Vacuum membrane distillation (VMD) has been studied as a separation process to remove volatile organic compounds from aqueous streams. A vapour pressure difference across a microporous hydrophobic membrane is the driving force for the mass transport through the membrane pores (this transport take...... place in vapour phase). The vapour pressure difference is obtained in VMD processes by applying a vacuum on one side of the membrane. The membrane acts as a mere support for the liquid-vapour equilibrium. The evaporation of the liquid stream takes place on the feed side of the membrane...... values; membrane type: PTFE/PP/PVDF; feed flow rate; feed temperature. A comparison is made between different thermodynamic models for calculating the vapour-liquid equilibrium at the membrane/pore interface. (C) 2004 Elsevier B.V. All rights reserved....

  7. Introduction to compressible fluid flow

    CERN Document Server

    Oosthuizen, Patrick H

    2013-01-01

    IntroductionThe Equations of Steady One-Dimensional Compressible FlowSome Fundamental Aspects of Compressible FlowOne-Dimensional Isentropic FlowNormal Shock WavesOblique Shock WavesExpansion Waves - Prandtl-Meyer FlowVariable Area FlowsAdiabatic Flow with FrictionFlow with Heat TransferLinearized Analysis of Two-Dimensional Compressible FlowsHypersonic and High-Temperature FlowsHigh-Temperature Gas EffectsLow-Density FlowsBibliographyAppendices

  8. Mammographic compression in Asian women.

    Science.gov (United States)

    Lau, Susie; Abdul Aziz, Yang Faridah; Ng, Kwan Hoong

    2017-01-01

    To investigate: (1) the variability of mammographic compression parameters amongst Asian women; and (2) the effects of reducing compression force on image quality and mean glandular dose (MGD) in Asian women based on phantom study. We retrospectively collected 15818 raw digital mammograms from 3772 Asian women aged 35-80 years who underwent screening or diagnostic mammography between Jan 2012 and Dec 2014 at our center. The mammograms were processed using a volumetric breast density (VBD) measurement software (Volpara) to assess compression force, compression pressure, compressed breast thickness (CBT), breast volume, VBD and MGD against breast contact area. The effects of reducing compression force on image quality and MGD were also evaluated based on measurement obtained from 105 Asian women, as well as using the RMI156 Mammographic Accreditation Phantom and polymethyl methacrylate (PMMA) slabs. Compression force, compression pressure, CBT, breast volume, VBD and MGD correlated significantly with breast contact area (pAsian women. The median compression force should be about 8.1 daN compared to the current 12.0 daN. Decreasing compression force from 12.0 daN to 9.0 daN increased CBT by 3.3±1.4 mm, MGD by 6.2-11.0%, and caused no significant effects on image quality (p>0.05). Force-standardized protocol led to widely variable compression parameters in Asian women. Based on phantom study, it is feasible to reduce compression force up to 32.5% with minimal effects on image quality and MGD.

  9. Exergoeconomic Assessment of Solar Absorption and Absorption–Compression Hybrid Refrigeration in Building Cooling

    Directory of Open Access Journals (Sweden)

    Yue Jing

    2018-02-01

    Full Text Available The paper mainly deals with the match of solar refrigeration, i.e., solar/natural gas-driven absorption chiller (SNGDAC, solar vapor compression–absorption integrated refrigeration system with parallel configuration (SVCAIRSPC, and solar absorption-subcooled compression hybrid cooling system (SASCHCS, and building cooling based on the exergoeconomics. Three types of building cooling are considered: Type 1 is the single-story building, type 2 includes the two-story and three-story buildings, and type 3 is the multi-story buildings. Besides this, two Chinese cities, Guangzhou and Turpan, are taken into account as well. The product cost flow rate is employed as the primary decision variable. The result exhibits that SNGDAC is considered as a suitable solution for type 1 buildings in Turpan, owing to its negligible natural gas consumption and lowest product cost flow rate. SVCAIRSPC is more applicable for type 2 buildings in Turpan because of its higher actual cooling capacity of absorption subsystem and lower fuel and product cost flow rate. Additionally, SASCHCS shows the most extensive cost-effectiveness, namely, its exergy destruction and product cost flow rate are both the lowest when used in all types of buildings in Guangzhou or type 3 buildings in Turpan. This paper is helpful to promote the application of solar cooling.

  10. Development and analysis of sustainable energy systems for building HVAC applications

    International Nuclear Information System (INIS)

    Khalid, F.; Dincer, I.; Rosen, M.A.

    2015-01-01

    The main HVAC applications considered in this paper are heating and cooling. Three newly developed systems for heating and cooling applications in buildings are proposed and assessed. Energy and exergy analyses are performed to assess the performance of heating, cooling and overall systems for each case, and the effects of various parameters on the energy and exergy efficiencies are examined. Also, the effect of changing the energy input for each system is also found in terms of overall efficiency. The overall system energy efficiency is found to be highest for the natural gas operated system with a vapour absorption chiller (system 1) at 27.5% and lowest for the photovoltaic (PV) and solar thermal operated system with vapour compression chiller (system 3) at 19.9%. The overall system exergy efficiency is found to be highest for the PV and solar thermal operated system with vapour compression chiller (system 3) at 3.9% and lowest for the PV and solar thermal operated system with heat pump (system 2) at 1.2%, respectively. - Highlights: • Three HVAC systems for buildings using renewable energy sources are proposed and assessed. • A performance improvement study is undertaken. • Parametric studies are carried out to determine the effects of various parameters on energy and exergy efficiencies

  11. Heat-flux enhancement by vapour-bubble nucleation in Rayleigh-Bénard turbulence

    NARCIS (Netherlands)

    Narezo Guzman, Daniela; Xie, Yanbo; Chen, S.; Fernandez Rivas, David; Sun, Chao; Lohse, Detlef; Ahlers, Günter

    2016-01-01

    We report on the enhancement of turbulent convective heat transport due to vapour-bubble nucleation at the bottom plate of a cylindrical Rayleigh–Bénard sample (aspect ratio 1.00, diameter 8.8 cm) filled with liquid. Microcavities acted as nucleation sites, allowing for well-controlled bubble

  12. ZnO based nanowires grown by chemical vapour deposition for selective hydrogenation of acetylene alcohols

    NARCIS (Netherlands)

    Protasova, L.N.; Rebrov, E.; Choy, K.L.; Pung, S.Y.; Engels, V.; Cabaj, M.; Wheatley, A.E.H.; Schouten, J.C.

    2011-01-01

    Vertically aligned ZnO nanowires (NWs) with a length of 1.5–10 µm and a mean diameter of ca. 150 nm were grown by chemical vapour deposition onto a c-oriented ZnO seed layer which was deposited by atomic layer deposition on Si substrates. The substrates were then spin-coated with an ethanol solution

  13. Expanding thermal plasma chemical vapour deposition of ZnO:Al layers for CIGS solar cells

    NARCIS (Netherlands)

    Sharma, K.; Williams, B.L.; Mittal, A.; Knoops, H.C.M.; Kniknie, B.J.; Bakker, N.J.; Kessels, W.M.M.; Schropp, R.E.I.; Creatore, M.

    2014-01-01

    Aluminium-doped zinc oxide (ZnO:Al) grown by expanding thermal plasma chemical vapour deposition (ETP-CVD) has demonstrated excellent electrical and optical properties, which make it an attractive candidate as a transparent conductive oxide for photovoltaic applications. However, when depositing

  14. Density profiles and collective excitations of a trapped two-component Fermi vapour

    International Nuclear Information System (INIS)

    Amoruso, M.; Meccoli, I.; Minguzzi, A.; Tosi, M.P.

    1999-08-01

    We discuss the ground state and the small-amplitude excitations of a degenerate vapour of fermionic atoms placed in two hyperfine states inside a spherical harmonic trap. An equations-of-motion approach is set up to discuss the hydrodynamic dissipation processes from the interactions between the two components of the fluid beyond mean-field theory and to emphasize analogies with spin dynamics and spin diffusion in a homogeneous Fermi liquid. The conditions for the establishment of a collisional regime via scattering against cold-atom impurities are analyzed. The equilibrium density profiles are then calculated for a two-component vapour of 40 K atoms: they are little modified by the interactions for presently relevant values of the system parameters, but spatial separation of the two components will spontaneously arise as the number of atoms in the trap is increased. The eigenmodes of collective oscillation in both the total particle number density and the concentration density are evaluated analytically in the special case of a symmetric two-component vapour in the collisional regime. The dispersion relation of the surface modes for the total particle density reduces in this case to that of a one-component Fermi vapour, whereas the frequencies of all other modes are shifted by the interactions. (author)

  15. Accuracy and conservatism of vapour intrusion algorithms for contaminated land management

    NARCIS (Netherlands)

    Provoost, J.; Reijnders, L.; Bonders, J.

    2013-01-01

    This paper provides a view on the suitability of screening-level vapour intrusion (VI) algorithms for contaminated land management. It focuses on the accuracy and level of conservatism for a number of screening-level algorithms used for VI into buildings. The paper discusses the published evidence

  16. Reaction of soda-lime-silica glass melt with water vapour at melting temperatures

    Czech Academy of Sciences Publication Activity Database

    Vernerová, Miroslava; Kloužek, Jaroslav; Němec, Lubomír

    2015-01-01

    Roč. 416, MAY 15 (2015), s. 21-30 ISSN 0022-3093 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melt * sulfate * water vapour * bubble nucleation * melt foaming * glass melting Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.825, year: 2015

  17. The fourth international symposium on inhaled particles and vapours, Edinburgh 22-26 September 1975

    International Nuclear Information System (INIS)

    Bailey, M.R.

    1975-11-01

    A brief account is given of the symposium, organised by the British Occupational Hygiene Society in co-operation with the European Communities. Its objective was to present the results of the latest research into the inhalation and retention of dusts and vapours, the way they are handled by the body, and their effects, with emphasis on the basic mechanisms involved. (author)

  18. Multiscale network model for simulating liquid water and water vapour transfer properties of porous materials

    NARCIS (Netherlands)

    Carmeliet, J.; Descamps, F.; Houvenaghel, G.

    1999-01-01

    A multiscale network model is presented to model unsaturated moisture transfer in hygroscopic capillary-porous materials showing a broad pore-size distribution. Both capillary effects and water sorption phenomena, water vapour and liquid water transfer are considered. The multiscale approach is

  19. The effect of air permeability of chemical protective clothing material on clothing vapour resistance

    NARCIS (Netherlands)

    Havenith, G.; Vuister, R.; Wammes, L.

    1996-01-01

    One of the major problems associated with Chemical Warfare Protective Clothing (CW) is the additional heat load created by the garments. For CW-overgarments, research in the direction of reducing material thickness and thus heat and vapour resistance have not resulted in major improvements. The

  20. Water vapour trends at several tropospheric levels over South America between 1973 and 2003

    International Nuclear Information System (INIS)

    Morales, L.; Mattar, C.; Da-Silva, L.; Abarca, R.

    2009-01-01

    In this paper water vapour trends were analyzed at several tropospheric levels over South America between 1973 and 2003. It was carried out using in situ values retrieved by 15 radiosonde stations and NCEP NCAR Reanalysis data (NNR). NNR and radiosonde water vapour data were linked to Koeppen-Geiger climatic zones to calculate anomalies, trends, and the non-parametric statistical significance for each mandatory level. A methodology used to process radiosonde data is shown. Water vapour trends in tropical climates presented positive decadal trends. This is statistically significant for the first mandatory levels retrieved by radiosonde. The highest values are presented in average with NNR; the decadal magnitude for climate Af being 0.15 g kg -1 for 1000 and 925 h Pa, and for climate As 0.27 g kg -1 for 925 and 850 h Pa. For non-tropical climates the magnitude trends of specific humidity are affected by the spatial resolution of NNR, which is seen when comparing the results received by the radiosondes. Finally, this paper shows the initial results of water vapour content trends in the last three decades over South America. Strong climatic events and synoptic oscillations were not commented upon.

  1. Vapour pressures and enthalpies of vaporization of a series of the linear n-alkyl acetates

    Czech Academy of Sciences Publication Activity Database

    Krasnykh, E. L.; Verevkin, S. P.; Koutek, Bohumír; Doubský, Jan

    2006-01-01

    Roč. 38, č. 6 (2006), s. 717-723 ISSN 0021-9614 Institutional research plan: CEZ:AV0Z40550506 Keywords : aliphatic acetates * transpiration method * vapour pressure * enthalpy of vaporization Subject RIV: CC - Organic Chemistry Impact factor: 1.842, year: 2006

  2. Supercooled liquid vapour pressures and related thermodynamic properties of polycyclic aromatic hydrocarbons determined by gas chromatography

    NARCIS (Netherlands)

    Haftka, J.J.H.; Parsons, J.R.; Govers, H.A.J.

    2006-01-01

    A gas chromatographic method using Kovats retention indices has been applied to determine the liquid vapour pressure (P-i), enthalpy of vaporization (Delta H-i) and difference in heat capacity between gas and liquid phase (Delta C-i) for a group of polycyclic aromatic hydrocarbons (PAHs). This group

  3. Vertical distribution of deuterium in atmospheric water vapour: problems in application to assess atmospheric condensation models

    International Nuclear Information System (INIS)

    Taylor, C.B.

    1984-01-01

    The paper assesses the use of the author's data by Rozanski and Sonntag to support a multi-box model of the vertical distribution of deuterium in atmospheric water vapour, in which exchange between vapour and falling precipitation produces a steeper deuterium concentration profile than simpler condensation models. The mean deuterium/altitude profile adopted by Rozanski and Sonntag for this purpose is only one of several very different mean profiles obtainable from the data by arbitrary selection and weighting procedures; although it can be made to match the specified multi-box model calculations for deuterium, there is a wide discrepancy between the actual and model mean mixing ratio profiles which cannot be ignored. Taken together, the mixing ratio and deuterium profiles indicate that mean vapour of the middle troposphere has been subjected to condensation at greater heights and lower temperatures than those considered in the model calculations. When this is taken into account, the data actually fit much better to the simpler condensation models. But the vapour samples represent meteorological situations too remote in time from primary precipitation events to permit definite conclusions on cloud system mechanisms. (Auth.)

  4. Using Peltier Cells to Study Solid-Liquid-Vapour Transitions and Supercooling

    Science.gov (United States)

    Torzo, Giacomo; Soletta, Isabella; Branca, Mario

    2007-01-01

    We propose an apparatus for teaching experimental thermodynamics in undergraduate introductory courses, using thermoelectric modules and a real-time data acquisition system. The device may be made at low cost, still providing an easy approach to the investigation of liquid-solid and liquid-vapour phase transitions and of metastable states…

  5. Surfactant assisted chemical vapour generation of silver for AAS and ICP-OES: a mechanistic study

    Czech Academy of Sciences Publication Activity Database

    Matoušek, Tomáš; Sturgeon, R. E.

    2003-01-01

    Roč. 18, č. 5 (2003), s. 487-494 ISSN 0267-9477 Institutional research plan: CEZ:AV0Z4031919 Keywords : vapour generation * ICP-OES * silver Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.200, year: 2003

  6. Application of lemongrass oil in vapour phase for the effective control of anthracnose of 'Sekaki' papaya.

    Science.gov (United States)

    Ali, A; Wee Pheng, T; Mustafa, M A

    2015-06-01

    To evaluate the potential use of lemongrass essential oil vapour as an alternative for synthetic fungicides in controlling anthracnose of papaya. Lemongrass oil used in the study was characterized using gas chromatography-flame ionization detection (GC-FID) before it was tested against anthracnose of papaya in vitro and in vivo. The GC-FID analysis showed that geranial (45·6%) and neral (34·3%) were the major components in lemongrass oil. In vitro study revealed that lemongrass oil vapour at all concentrations tested (33, 66, 132, 264 and 528 μl l(-1) ) suppressed the mycelial growth and conidial germination of Colletotrichum gloeosporioides. For the in vivo study, 'Sekaki' papaya were exposed to lemongrass oil fumigation (0, 7, 14, 28 μl l(-1) ) for 18 h and at room temperature for 9 days. Lemongrass oil vapour at the concentration of 28 μl l(-1) was most effective against anthracnose of artificially inoculated papaya fruit while quality parameters of papaya were not significantly altered. This suggests that lemongrass oil vapour can control anthracnose disease development on papaya without affecting its natural ripening process. The potential practical application of this technology can reduce reliance on synthetic fungicides for the control of postharvest diseases in papaya. © 2015 The Society for Applied Microbiology.

  7. Water vapour rises from the cooling towers for the ATLAS detector at Point 1

    CERN Multimedia

    Brice, Maximilien

    2015-01-01

    Electronics on the ATLAS detector produce heat when the experiment is running. An elaborate cooling system keeps the detector from overheating. On the surface, the warm water vapour that rises from the detector 100metres underground is clearly visible from the ATLAS cooling towers on the CERN Meyrin site in Switzerland.

  8. Vapour Removal from the Greenhouse Using Forced Ventilation when Applying a Thermal Screen

    NARCIS (Netherlands)

    Campen, J.B.

    2008-01-01

    The objective of this study is to dimension a system capable of removing water vapour mainly generated by evaporation of the crop when a thermal screen is applied. The humid greenhouse air is replaced by cold dry outside air using an air distribution system. The dry air is injected above the

  9. Chemical vapour generation of silver: reduced palladium as permanent reaction modifier for enhanced performance

    Czech Academy of Sciences Publication Activity Database

    Matoušek, Tomáš; Sturgeon, R. E.

    2004-01-01

    Roč. 19, č. 8 (2004), s. 1014-1017 ISSN 0267-9477 R&D Projects: GA ČR GA203/01/0453 Institutional research plan: CEZ:AV0Z4031919 Keywords : chemical vapour generation * chemical modification * silver Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.926, year: 2004

  10. ArF Laser -Induced Chemical Vapour Deposition of Polythiene Films from Carbon Disulfide

    Czech Academy of Sciences Publication Activity Database

    Tomovska, R.; Bastl, Zdeněk; Vorlíček, Vladimír; Vacek, Karel; Šubrt, Jan; Plzák, Zbyněk; Pola, Josef

    2003-01-01

    Roč. 107, č. 36 (2003), s. 9793-9801 ISSN 1089-5647 R&D Projects: GA MŠk ME 612 Institutional research plan: CEZ:AV0Z4032918; CEZ:AV0Z4040901 Keywords : laser photolysis * ArF * chemical vapour deposition Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.679, year: 2003

  11. Determining the vapour pressures of plant volatiles from gas chromatographic retention data

    Czech Academy of Sciences Publication Activity Database

    Hoskovec, Michal; Grygarová, D.; Cvačka, Josef; Streinz, Ludvík; Zima, J.; Verevkin, S. P.; Koutek, Bohumír

    2005-01-01

    Roč. 1083, - (2005), s. 161-172 ISSN 0021-9673 Institutional research plan: CEZ:AV0Z4055905 Keywords : vapour pressure * thermodinamic parameters * plant volatiles Subject RIV: CC - Organic Chemistry Impact factor: 3.096, year: 2005

  12. Detection of the contamination of air by tritiated water vapour around the reactor EL3

    International Nuclear Information System (INIS)

    Lebouleux, P.; Ardellier, A.; Valero, S.

    1968-01-01

    The authors describe the apparatus used for the detection of the tritiated water vapour contamination in the air around the reactor EL 3. The apparatus consists of two air-circulation ionisation chambers; the air in one of these is dried by passage through a silica-gel column. By carrying out a differential measurement of the ionization currents, it is possible to measure the tritiated water vapour concentration. A theoretical study of the response of the chambers is carried out for two types of emission of the tritiated water vapour: continuous, or in bursts. The experimental work comprises: calibration in the measurement range employed; study of the selectivity for other active gases; study of typical accidents; the interpretation of the results in the case of discontinuous emission, taking into account the desorption from the walls of the measurement chamber, a phenomenon which is observed during the emptying process. The authors give finally actual examples of how to use the results. The apparatus built makes it possible to detect, in less than ten minutes, contamination by tritiated water vapour in the presence of other active gases, in a measurement range of between 3 and 2200 MPC, and with an accuracy of about 25 per cent. A transposition to calculations of the risk to workers should be made with the utmost caution; an envelope of this risk can be drawn up more or less accurately depending on particular cases. (authors) [fr

  13. Range-energy relations and stopping powers of organic liquids and vapours for alpha particles

    International Nuclear Information System (INIS)

    Akhavan-Rezayat, A.; Palmer, R.B.J.

    1980-01-01

    Experimental range-energy relations are presented for alpha particles in methyl alcohol, propyl alcohol, dichloromethane, chloroform and carbon tetrachloride in both the liquid and vapour phases. Stopping power values for these materials and for oxygen gas over the energy range 1.0-8.0 MeV are also given. From these results stopping powers have been derived for the -CH 2 -group and for -Cl occurring in chemical combination in the liquid and vapour phases. The molecular stopping power in the vapour phase is shown to exceed that in the liquid phase by 2-6% below 2 MeV, reducing to negligible differences at about 5 MeV for the materials directly investigated and for the -Cl atom. No significant phase effect is observed for the -CH 2 -group, but it is noted that the uncertainties in the values of the derived stopping powers are much greater in this case. Comparison of the experimental molecular stopping powers with values calculated from elemental values using the Bragg additivity rule shows agreement for vapours but not for liquids. (author)

  14. Vapour Pressure and Adiabatic Cooling from Champagne: Slow-Motion Visualization of Gas Thermodynamics

    Science.gov (United States)

    Vollmer, Michael; Mollmann, Klaus-Peter

    2012-01-01

    The recent introduction of inexpensive high-speed cameras offers a new experimental approach to many simple but fast-occurring events in physics. In this paper, the authors present two simple demonstration experiments recorded with high-speed cameras in the fields of gas dynamics and thermal physics. The experiments feature vapour pressure effects…

  15. Behaviour of carbon dioxide and water vapour flux densities from a disturbed raised peat bog

    NARCIS (Netherlands)

    Nieveen, J.P.; Jacobs, A.F.G.

    2002-01-01

    Measurements of carbon dioxide and water vapour flux densities were carried out for a disturbed raised peat bog in the north of the Netherlands during an 18 month continuous experiment. Tussock grass (sp. Molinea caerulae) mainly dominated the vegetation of the bog area. The maximum leaf area index

  16. Hydrogen and carbon vapour pressure isotope effects in liquid fluoroform studied by density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Oi, Takao; Mitome, Ryota; Yanase, Satoshi [Sophia Univ., Tokyo (Japan). Faculty of Science and Technology

    2017-06-01

    H/D and {sup 12}C/{sup 13}C vapour pressure isotope effects (VPIEs) in liquid fluoroform (CHF{sub 3}) were studied at the MPW1PW91/6-31 ++ G(d) level of theory. The CHF{sub 3} monomer and CHF{sub 3} molecules surrounded by other CHF{sub 3} molecules in every direction in CHF{sub 3} clusters were used as model molecules of vapour and liquid CHF{sub 3}. Although experimental results in which the vapour pressure of liquid {sup 12}CHF{sub 3} is higher than that of liquid {sup 12}CDF{sub 3} and the vapour pressure of liquid {sup 13}CHF{sub 3} is higher than that of liquid {sup 12}CHF{sub 3} between 125 and 212 K were qualitatively reproduced, the present calculations overestimated the H/D VPIE and underestimated the {sup 12}C/{sup 13}C VPIE. Temperature-dependent intermolecular interactions between hydrogen and fluorine atoms of neighbouring molecules were required to explain the temperature dependences of both H/D and {sup 12}C/{sup 13}C VPIEs.

  17. Discovery of water vapour in the carbon star V Cygni from observations with Herschel/HIFI

    NARCIS (Netherlands)

    Neufeld, D. A.; Gonzalez-Alfonso, E.; Melnick, G.; Pulecka, M.; Schmidt, M.; Szczerba, R.; Bujarrabal, V.; Alcolea, J.; Cernicharo, J.; Decin, L.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A. P.; Menten, K.; Olofsson, H.; Planesas, P.; Schoier, F. L.; Teyssier, D.; Waters, L. B. F. M.; Edwards, K.; McCoey, C.; Shipman, R.; Jellema, W.; de Graauw, T.; Ossenkopf, V.; Schieder, R.; Philipp, S.

    2010-01-01

    We report the discovery of water vapour toward the carbon star V Cygni. We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 1(11)-0(00) para-water transition at 1113.3430 GHz in the upper sideband of the Band 4b receiver. The observed spectral line profile is nearly

  18. Modelling and interpreting the isotopic composition of water vapour in convective updrafts

    Directory of Open Access Journals (Sweden)

    M. Bolot

    2013-08-01

    Full Text Available The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener–Bergeron–Findeisen process. As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  19. Modelling and interpreting the isotopic composition of water vapour in convective updrafts

    Science.gov (United States)

    Bolot, M.; Legras, B.; Moyer, E. J.

    2013-08-01

    The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener-Bergeron-Findeisen process). As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  20. Modelling and intepreting the isotopic composition of water vapour in convective updrafts

    Science.gov (United States)

    Bolot, M.; Legras, B.; Moyer, E. J.

    2012-08-01

    The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener-Bergeron-Findeisen process). As all of these processes are related to updraft strength, droplet size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  1. Adiabatic compression and radiative compression of magnetic fields

    International Nuclear Information System (INIS)

    Woods, C.H.

    1980-01-01

    Flux is conserved during mechanical compression of magnetic fields for both nonrelativistic and relativistic compressors. However, the relativistic compressor generates radiation, which can carry up to twice the energy content of the magnetic field compressed adiabatically. The radiation may be either confined or allowed to escape

  2. Waves and compressible flow

    CERN Document Server

    Ockendon, Hilary

    2016-01-01

    Now in its second edition, this book continues to give readers a broad mathematical basis for modelling and understanding the wide range of wave phenomena encountered in modern applications.  New and expanded material includes topics such as elastoplastic waves and waves in plasmas, as well as new exercises.  Comprehensive collections of models are used to illustrate the underpinning mathematical methodologies, which include the basic ideas of the relevant partial differential equations, characteristics, ray theory, asymptotic analysis, dispersion, shock waves, and weak solutions. Although the main focus is on compressible fluid flow, the authors show how intimately gasdynamic waves are related to wave phenomena in many other areas of physical science.   Special emphasis is placed on the development of physical intuition to supplement and reinforce analytical thinking. Each chapter includes a complete set of carefully prepared exercises, making this a suitable textbook for students in applied mathematics, ...

  3. Characterization of aqueous interactions of copper-doped phosphate-based glasses by vapour sorption.

    Science.gov (United States)

    Stähli, Christoph; Shah Mohammadi, Maziar; Waters, Kristian E; Nazhat, Showan N

    2014-07-01

    Owing to their adjustable dissolution properties, phosphate-based glasses (PGs) are promising materials for the controlled release of bioinorganics, such as copper ions. This study describes a vapour sorption method that allowed for the investigation of the kinetics and mechanisms of aqueous interactions of PGs of the formulation 50P2O5-30CaO-(20-x)Na2O-xCuO (x=0, 1, 5 and 10mol.%). Initial characterization was performed using (31)P magic angle spinning nuclear magnetic resonance and attenuated total reflectance-Fourier transform infrared spectroscopy. Increasing CuO content resulted in chemical shifts of the predominant Q(2) NMR peak and of the (POP)as and (PO(-)) Fourier transform infrared absorptions, owing to the higher strength of the POCu bond compared to PONa. Vapour sorption and desorption were gravimetrically measured in PG powders exposed to variable relative humidity (RH). Sorption was negligible below 70% RH and increased exponentially with RH from 70 to 90%, where it exhibited a negative correlation with CuO content. Vapour sorption in 0% and 1% CuO glasses resulted in phosphate chain hydration and hydrolysis, as evidenced by protonated Q(0)(1H) and Q(1)(1H) species. Dissolution rates in deionized water showed a linear correlation (R(2)>0.99) with vapour sorption. Furthermore, cation release rates could be predicted based on dissolution rates and PG composition. The release of orthophosphate and short polyphosphate species corroborates the action of hydrolysis and was correlated with pH changes. In conclusion, the agreement between vapour sorption and routine characterization techniques in water demonstrates the potential of this method for the study of PG aqueous reactions. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  4. Application specific compression : final report.

    Energy Technology Data Exchange (ETDEWEB)

    Melgaard, David Kennett; Byrne, Raymond Harry; Myers, Daniel S.; Harrison, Carol D.; Lee, David S.; Lewis, Phillip J.; Carlson, Jeffrey J.

    2008-12-01

    With the continuing development of more capable data gathering sensors, comes an increased demand on the bandwidth for transmitting larger quantities of data. To help counteract that trend, a study was undertaken to determine appropriate lossy data compression strategies for minimizing their impact on target detection and characterization. The survey of current compression techniques led us to the conclusion that wavelet compression was well suited for this purpose. Wavelet analysis essentially applies a low-pass and high-pass filter to the data, converting the data into the related coefficients that maintain spatial information as well as frequency information. Wavelet compression is achieved by zeroing the coefficients that pertain to the noise in the signal, i.e. the high frequency, low amplitude portion. This approach is well suited for our goal because it reduces the noise in the signal with only minimal impact on the larger, lower frequency target signatures. The resulting coefficients can then be encoded using lossless techniques with higher compression levels because of the lower entropy and significant number of zeros. No significant signal degradation or difficulties in target characterization or detection were observed or measured when wavelet compression was applied to simulated and real data, even when over 80% of the coefficients were zeroed. While the exact level of compression will be data set dependent, for the data sets we studied, compression factors over 10 were found to be satisfactory where conventional lossless techniques achieved levels of less than 3.

  5. Compressed Baryonic Matter of Astrophysics

    OpenAIRE

    Guo, Yanjun; Xu, Renxin

    2013-01-01

    Baryonic matter in the core of a massive and evolved star is compressed significantly to form a supra-nuclear object, and compressed baryonic matter (CBM) is then produced after supernova. The state of cold matter at a few nuclear density is pedagogically reviewed, with significant attention paid to a possible quark-cluster state conjectured from an astrophysical point of view.

  6. Streaming Compression of Hexahedral Meshes

    Energy Technology Data Exchange (ETDEWEB)

    Isenburg, M; Courbet, C

    2010-02-03

    We describe a method for streaming compression of hexahedral meshes. Given an interleaved stream of vertices and hexahedral our coder incrementally compresses the mesh in the presented order. Our coder is extremely memory efficient when the input stream documents when vertices are referenced for the last time (i.e. when it contains topological finalization tags). Our coder then continuously releases and reuses data structures that no longer contribute to compressing the remainder of the stream. This means in practice that our coder has only a small fraction of the whole mesh in memory at any time. We can therefore compress very large meshes - even meshes that do not file in memory. Compared to traditional, non-streaming approaches that load the entire mesh and globally reorder it during compression, our algorithm trades a less compact compressed representation for significant gains in speed, memory, and I/O efficiency. For example, on the 456k hexahedra 'blade' mesh, our coder is twice as fast and uses 88 times less memory (only 3.1 MB) with the compressed file increasing about 3% in size. We also present the first scheme for predictive compression of properties associated with hexahedral cells.

  7. Data Compression with Linear Algebra

    OpenAIRE

    Etler, David

    2015-01-01

    A presentation on the applications of linear algebra to image compression. Covers entropy, the discrete cosine transform, thresholding, quantization, and examples of images compressed with DCT. Given in Spring 2015 at Ocean County College as part of the honors program.

  8. Images compression in nuclear medicine

    International Nuclear Information System (INIS)

    Rebelo, M.S.; Furuie, S.S.; Moura, L.

    1992-01-01

    The performance of two methods for images compression in nuclear medicine was evaluated. The LZW precise, and Cosine Transformed, approximate, methods were analyzed. The results were obtained, showing that the utilization of approximated method produced images with an agreeable quality for visual analysis and compression rates, considerably high than precise method. (C.G.C.)

  9. Compressive Sensing in Communication Systems

    DEFF Research Database (Denmark)

    Fyhn, Karsten

    2013-01-01

    . The need for cheaper, smarter and more energy efficient wireless devices is greater now than ever. This thesis addresses this problem and concerns the application of the recently developed sampling theory of compressive sensing in communication systems. Compressive sensing is the merging of signal...... acquisition and compression. It allows for sampling a signal with a rate below the bound dictated by the celebrated Shannon-Nyquist sampling theorem. In some communication systems this necessary minimum sample rate, dictated by the Shannon-Nyquist sampling theorem, is so high it is at the limit of what...... with using compressive sensing in communication systems. The main contribution of this thesis is two-fold: 1) a new compressive sensing hardware structure for spread spectrum signals, which is simpler than the current state-of-the-art, and 2) a range of algorithms for parameter estimation for the class...

  10. Numerical Simulation of Pulsation Flow in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads

    Science.gov (United States)

    Seryakov, A. V.; Konkin, A. V.

    2017-11-01

    The results of the numerical simulation of pulsations in the Laval-liked vapour channel of short low-temperature range heat pipes (HPs) are presented. The numerical results confirmed the experimentally obtained increase of the frequency of pulsations in the vapour channel of short HPs with increasing overheat of the porous evaporator relative to the boiling point of the working fluid. The occurrence of pressure pulsations inside the vapour channel in a short HPs is a complex phenomenon associated with the boiling beginning in the capillary-porous evaporator at high heat loads, and appearance the excess amount of vapour above it, leading to the increase in pressure P to a value at which the boiling point TB of the working fluid becomes higher than the evaporator temperature Tev. Vapour clot spreads through the vapour channel and condense, and then a rarefaction wave return from condenser in the evaporator, the boiling in which is resumed and the next cycle of the pulsations is repeated. Numerical simulation was performed using finite element method implemented in the commercial program ANSYS Multiphisics 14.5 in the two-dimensional setting of axis symmetric moist vapour flow with third kind boundary conditions.

  11. The Investigation of Isotopic Composition of Precipitation and water vapour by Using Air Mass Trajectories and Meteorological Parameters

    International Nuclear Information System (INIS)

    Dirican, A.; Acar, Y.; Demircan, M.

    2002-01-01

    In last century there are so many studies were carried out about stable isotopes of precipitation. The Researchers, study in this field directed to examine origin and transport of water vapour. To investigate the conditions of precipitation formation parallel with climatic changes, stable isotopes using as a powerful tool. So that a project coordinated by IAEA. In this presentation we will give some parts of this project which was carried out in Turkey. First results were obtained for 2001 year. The one of the first result which was obtained in this project is the relation between air temperature and isotopic composition of precipitation collected in Ankara Antalya and Adana station. Second was the observation of temporal variation of stable isotope composition in precipitation and water vapour in relation with water vapour transport. δD and δ 18 O content of atmospheric water vapour examined for January - December 2001 time interval. 27 precipitation event had been examined, starting from endengered place and following to trajectories until to reach Turkey, by using ground level and 500mbar synoptic charts. The observed δD and δ 18 O variations of water vapour is related with the endengered place (Atlantic Ocean, Mediterranean Sea, etc.) of water vapour. The isotopic composition of local precipitation forms by regional meteorological factors. In this study δD and δ 18 O relation of event, daily precipitation and water vapour were defined

  12. Vapour pressures and vapour-liquid equilibria of propyl acetate and isobutyl acetate with ethanol or 2-propanol at 0.15 MPa. Binary systems

    Directory of Open Access Journals (Sweden)

    Susial Pedro

    2012-01-01

    Full Text Available Vapour pressures of propyl acetate, isobutyl acetate and 2-propanol from 0.004 to 1.6 MPa absolute pressure and VLE data for the binary systems propyl acetate+ethanol, propyl acetate+2-propanol, isobutyl acetate+ethanol and isobutyl acetate+2-propanol at 0.15 MPa have been determined. The experimental VLE data were verified with the test of van Ness and the Fredenslund criterion. The propyl acetate+ethanol or +2-propanol binary systems have an azeotropic point at 0.15 MPa. The different versions of the UNIFAC and ASOG group contribution models were applied.

  13. THE USE OF POROUS CERAMICS FOR EVAPORATIVE AND EVAPORATIVE – VAPOR –COMPRESSION SYSTEMS

    Directory of Open Access Journals (Sweden)

    Cheban D.N.

    2013-04-01

    Full Text Available The use of natural evaporative cooling is one of technical solutions of problem of energy efficiency in air conditioning systems. The use of evaporative cooling in the first combined cooling stage allows reducing the load on the condenser of the cooling machine due to reducing of the condensing temperature. This combination allows the use of this type of system in any climatic conditions, including regions with small water resources. Multi-porous ceramic structure is used in evaporative air coolers and water coolers in this case. The objective of this paper is to show advantages of the using of porous ceramic as a working attachment, and to show advantages of the proposed scheme of compression-evaporation systems in comparison with standard vapor compression systems. Experimental research proved the fact, that in the film mode cooling efficiency of air flow is between EA=0,6÷0,7 and is slightly dependent of water flow. For countries with hot and dry climate where reserves of water are limited, it is recommended to use cyclical regime with EA≈0,65 value, or to use channel regime with a value of EA≈0,55. This leads to considerable energy savings. It has been determined, that combined air conditioning system is completely closed on the consumption of water at the parameters of the outside air equal to tA =32ºC and XA>13g/kg (in system with direct evaporative cooling machine, and tA=32ºC and XA>12g/kg (in system with indirect evaporative cooling machine. With these parameters, the cost of water in evaporative cooling stage can be fully compensated by condensate from the evaporator chiller.

  14. Evaluation of mammogram compression efficiency

    International Nuclear Information System (INIS)

    Przelaskowski, A.; Surowski, P.; Kukula, A.

    2005-01-01

    Lossy image coding significantly improves performance over lossless methods, but a reliable control of diagnostic accuracy regarding compressed images is necessary. The acceptable range of compression ratios must be safe with respect to as many objective criteria as possible. This study evaluates the compression efficiency of digital mammograms in both numerically lossless (reversible) and lossy (irreversible) manner. Effective compression methods and concepts were examined to increase archiving and telediagnosis performance. Lossless compression as a primary applicable tool for medical applications was verified on a set 131 mammograms. Moreover, nine radiologists participated in the evaluation of lossy compression of mammograms. Subjective rating of diagnostically important features brought a set of mean rates given for each test image. The lesion detection test resulted in binary decision data analyzed statistically. The radiologists rated and interpreted malignant and benign lesions, representative pathology symptoms, and other structures susceptible to compression distortions contained in 22 original and 62 reconstructed mammograms. Test mammograms were collected in two radiology centers for three years and then selected according to diagnostic content suitable for an evaluation of compression effects. Lossless compression efficiency of the tested coders varied, but CALIC, JPEG-LS, and SPIHT performed the best. The evaluation of lossy compression effects affecting detection ability was based on ROC-like analysis. Assuming a two-sided significance level of p=0.05, the null hypothesis that lower bit rate reconstructions are as useful for diagnosis as the originals was false in sensitivity tests with 0.04 bpp mammograms. However, verification of the same hypothesis with 0.1 bpp reconstructions suggested their acceptance. Moreover, the 1 bpp reconstructions were rated very similarly to the original mammograms in the diagnostic quality evaluation test, but the

  15. Isothermal (vapour + liquid) equilibrium for binary mixtures of (tetrahydrofuran + 1,1,2,2-tetrachloroethane or tetrachloroethene) at nine temperatures

    International Nuclear Information System (INIS)

    Garriga, R.; Perez, P.; Gracia, M.

    2006-01-01

    Vapour pressures of (tetrahydrofuran + 1,1,2,2-tetrachloroethane, or tetrachloroethene) at nine temperatures between T = 283.15 K and T = 323.15 K were measured by a static method. The reduction of the vapour pressures data to obtain activity coefficients and excess molar Gibbs energies was carried out by fitting the vapour pressure data to the Redlich-Kister polynomial according to Barker's method. Excess molar volumes were also measured at T 298.15 K. A comparative analysis about the thermodynamic behaviour of both systems is performed, in terms of hydrogen bonding and electron-donor-acceptor interactions, as well as the resonance effect in tetrachloroethene

  16. Design and simulation of a heat transformer of a directly solar-driven diffusion absorption chiller; Auslegung und Simulation von Waermeuebertragern einer direkt solarthermisch angetriebenen Diffusions-Absorptionskaeltemaschine

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Josua; Schmid, Fabian; Spindler, Klaus [Stuttgart Univ. (DE). Inst. fuer Thermodynamik und Waermetechnik (ITW)

    2011-07-01

    The ITW is working on a directly solar-driven diffusion absorption chiller. Solar cooling offers vast potential for saving fossil resources, e.g. owing to the good temporal agreement between insolation and cold demand for cooling of office buildings and domestic buildings. So far, the focus has been on central systems with indirect solar thermal operation. Direct solar thermal plants can be decentral. A diffusion-absorption refrigeration system without mechanical components was constructed. Solvent circulation is achieved by the thermosyphon principle, which makes the plant noiseless, wear-free, and low-maintenance. In the course of a study, a mathematical model of the heat exchangers was established on the basis of the heat transfer equations, and optimisation suggestions for the heat exchanger were identified on this basis. The influence of the pressure gradient - which is decisive -, and the influence of geometry and materials were investigated. The simulations were validated by measurements. Concrete optimisation potentials were identified, and first suggestions were implemented. [German] Am ITW wird intensiv an einer direkt solarthermisch angetriebenen Diffusions-Absorptionskaeltemaschine (DAKM) geforscht. Die solare Kuehlung bietet grosse Potentiale zur Einsparung fossiler Energietraeger. Ein Grund dafuer ist die gute zeitliche Uebereinstimmung zwischen Solarstrahlung und dem Kaeltebedarf fuer die Kuehlung von Wohngebaeuden und Bueros. Bislang standen zentrale und indirekt solarthermisch angetriebene Systeme zur Kaelteerzeugung im Fokus. Die direkt solarthermisch angetriebene Anlage kann auf Grund ihres neuen Konzepts dezentral aufgebaut und betrieben werden. Auf Grundlage des Diffusions-Absorptionskaelteprozesses wurde eine Anlage gebaut, die ohne mechanische Bauteile funktioniert. Der Loesungsmittelumlauf erfolgt durch das Thermosiphonprinzip. Dadurch ist die Anlage im Betrieb geraeuschlos, verschleissfrei und wartungsarm. Im Rahmen einer Studienarbeit

  17. Collisional effects on metastable atom population in vapour generated by electron beam heating

    International Nuclear Information System (INIS)

    Dikshit, B; Majumder, A; Bhatia, M S; Mago, V K

    2008-01-01

    The metastable atom population distribution in a free expanding uranium vapour generated by electron beam (e-beam) heating is expected to depart from its original value near the source due to atom-atom collisions and interaction with electrons of the e-beam generated plasma co-expanding with the vapour. To investigate the dynamics of the electron-atom and atom-atom interactions at different e-beam powers (or source temperatures), probing of the atomic population in ground (0 cm -1 ) and 620 cm -1 metastable states of uranium was carried out by the absorption technique using a hollow cathode discharge lamp. The excitation temperature of vapour at a distance ∼30 cm from the source was calculated on the basis of the measured ratio of populations in 620 to 0 cm -1 states and it was found to be much lower than both the source temperature and estimated translational temperature of the vapour that is cooled by adiabatic free expansion. This indicated relaxation of the metastable atoms by collisions with low energy plasma electrons was so significant that it brings the excitation temperature below the translational temperature of the vapour. So, with increase in e-beam power and hence atom density, frequent atom-atom collisions are expected to establish equilibrium between the excitation and translational temperatures, resulting in an increase in the excitation temperature (i.e. heating of vapour). This has been confirmed by analysing the experimentally observed growth pattern of the curve for excitation temperature with e-beam power. From the observed excitation temperature at low e-beam power when atom-atom collisions can be neglected, the total de-excitation cross section for relaxation of the 620 cm -1 state by interaction with low energy electrons was estimated and was found to be ∼10 -14 cm 2 . Finally using this value of cross section, the extent of excitational cooling and heating by electron-atom and atom-atom collisions are described at higher e-beam powers

  18. GPS water vapour tomography: preliminary results from the ESCOMPTE field experiment

    Science.gov (United States)

    Champollion, C.; Masson, F.; Bouin, M.-N.; Walpersdorf, A.; Doerflinger, E.; Bock, O.; Van Baelen, J.

    2005-03-01

    Water vapour plays a major role in atmospheric processes but remains difficult to quantify due to its high variability in time and space and the sparse set of available measurements. The GPS has proved its capacity to measure the integrated water vapour at zenith with the same accuracy as other methods. Recent studies show that it is possible to quantify the integrated water vapour in the line of sight of the GPS satellite. These observations can be used to study the 3D heterogeneity of the troposphere using tomographic techniques. We develop three-dimensional tomographic software to model the three-dimensional distribution of the tropospheric water vapour from GPS data. First, the tomographic software is validated by simulations based on the realistic ESCOMPTE GPS network configuration. Without a priori information, the absolute value of water vapour is less resolved as opposed to relative horizontal variations. During the ESCOMPTE field experiment, a dense network of 17 dual frequency GPS receivers was operated for 2 weeks within a 20×20-km area around Marseille (southern France). The network extends from sea level to the top of the Etoile chain (˜700 m high). Optimal results have been obtained with time windows of 30-min intervals and input data evaluation every 15 min. The optimal grid for the ESCOMTE geometrical configuration has a horizontal step size of 0.05°×0.05° and 500 m vertical step size. Second, we have compared the results of real data inversions with independent observations. Three inversions have been compared to three successive radiosonde launches and shown to be consistent. A good resolution compared to the a priori information is obtained up to heights of 3000 m. A humidity spike at 4000-m altitude remains unresolved. The reason is probably that the signal is spread homogeneously over the whole network and that such a feature is not resolvable by tomographic techniques. The results of our pure GPS inversion show a correlation with

  19. Evaluation of niobium dimethylamino-ethoxide for chemical vapour deposition of niobium oxide thin films

    International Nuclear Information System (INIS)

    Dabirian, Ali; Kuzminykh, Yury; Wagner, Estelle; Benvenuti, Giacomo; Rushworth, Simon; Hoffmann, Patrik

    2014-01-01

    Chemical vapour deposition (CVD) processes depend on the availability of suitable precursors. Precursors that deliver a stable vapour pressure are favourable in classical CVD processes, as they ensure process reproducibility. In high vacuum CVD (HV-CVD) process vapour pressure stability of the precursor is of particular importance, since no carrier gas assisted transport can be used. The dimeric Nb 2 (OEt) 10 does not fulfil this requirement since it partially dissociates upon heating. Dimethylamino functionalization of an ethoxy ligand of Nb(OEt) 5 acts as an octahedral field completing entity and leads to Nb(OEt) 4 (dmae). We show that Nb(OEt) 4 (dmae) evaporates as monomeric molecule and ensures a stable vapour pressure and, consequently, stable flow. A set of HV-CVD experiments were conducted using this precursor by projecting a graded molecular beam of the precursor onto the substrate at deposition temperatures from 320 °C to 650 °C. Film growth rates ranging from 8 nm·h −1 to values larger than 400 nm·h −1 can be obtained in this system illustrating the high level of control available over the film growth process. Classical CVD limiting conditions along with the recently reported adsorption–reaction limited conditions are observed and the chemical composition, and microstructural and optical properties of the films are related to the corresponding growth regime. Nb(OEt) 4 (dmae) provides a large process window of deposition temperatures and precursor fluxes over which carbon-free and polycrystalline niobium oxide films with growth rates proportional to precursor flux are obtained. This feature makes Nb(OEt) 4 (dmae) an attractive precursor for combinatorial CVD of niobium containing complex oxide films that are finding an increasing interest in photonics and photoelectrochemical water splitting applications. The adsorption–reaction limited conditions provide extremely small growth rates comparable to an atomic layer deposition (ALD) process

  20. Compression etiology in tendinopathy.

    Science.gov (United States)

    Almekinders, Louis C; Weinhold, Paul S; Maffulli, Nicola

    2003-10-01

    Recent studies have emphasized that the etiology of tendinopathy is not as simple as was once thought. The etiology is likely to be multifactorial. Etiologic factors may include some of the traditional factors such as overuse, inflexibility, and equipment problems; however, other factors need to be considered as well, such as age-related tendon degeneration and biomechanical considerations as outlined in this article. More research is needed to determine the significance of stress-shielding and compression in tendinopathy. If they are confirmed to play a role, this finding may significantly alter our approach in both prevention and in treatment through exercise therapy. The current biomechanical studies indicate that certain joint positions are more likely to place tensile stress on the area of the tendon commonly affected by tendinopathy. These joint positions seem to be different than the traditional positions for stretching exercises used for prevention and rehabilitation of tendinopathic conditions. Incorporation of different joint positions during stretching exercises may exert more uniform, controlled tensile stress on these affected areas of the tendon and avoid stresshielding. These exercises may be able to better maintain the mechanical strength of that region of the tendon and thereby avoid injury. Alternatively, they could more uniformly stress a healing area of the tendon in a controlled manner, and thereby stimulate healing once an injury has occurred. Additional work will have to prove if a change in rehabilitation exercises is more efficacious that current techniques.