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Sample records for absorption heat

  1. Absorption heat pumps

    Huhtinen, M.; Heikkilae, M.; Andersson, R.

    1987-03-01

    The aim of the study was to analyze the technical and economic feasibility of absorption heat pumps in Finland. The work was done as a case study: the technical and economic analyses have been carried out for six different cases, where in each the suitable size and type of the heat pump plant and the auxiliary components and connections were specified. The study also detailed the costs concerning the procurement, installation and test runs of the machinery, as well as the savings in energy costs incurred by the introduction of the plant. Conclusions were drawn of the economic viability of the applications studied. The following cases were analyzed: heat recovery from flue gases and productin of district heat in plants using peat, natural gas, and municipal wastes as a fuel. Heat recovery in the pulp and paper industry for the upgrading of pressure of secondary steam and for the heating of white liquor and combustion and drying the air. Heat recovery in a peat-fulled heat and power plant from flue gases that have been used for the drying of peat. According to the study, the absorption heat pump suits best to the production of district heat, when the heat source is the primary energy is steam produced by the boiler. Included in the flue as condensing is the purification of flue gases. Accordingly, benefit is gained on two levels in thick applications. In heat and power plants the use of absorption heat pumps is less economical, due to the fact that the steam used by the pump reduces the production of electricity, which is rated clearly higher than heat.

  2. Solar heating and cooling with absorption refrigeration

    Montlló Casabayó, Gerard

    2010-01-01

    This project is focused on solar heating and cooling installations that use solar thermal energy to produce heat for domestic hot water or space heating, and cooling for air conditioning through absorption refrigeration cycle. The first part of the project is a literature review of said technology. The main components of such installations are described and results and conclusions from existing installations are reviewed. The second part is focused on designing, modelling and simula...

  3. Liquid for absorption of solar heat

    Nakamura, T.; Iwamoto, Y.; Kadotani, K.; Marui, T.

    1984-11-13

    A liquid for the absorption of solar heat, useful as an heat-absorbing medium in water heaters and heat collectors comprises: a dispersing medium selected from the group consisting of propylene glycol, mixture of propylene glycol with water, mixture of propylene glycol with water and glycerin, and mixture of glycerin with water, a dispersant selected from the group consisting of polyvinylpyrrolidone, caramel, and mixture of polyvinylpyrrolidone with caramel, and a powdered activated carbon as a black coloring material.

  4. Cooling with solar heat. Absorption refrigerator; Mit Sonnenwaerme kuehlen. Absorptionskaeltemaschine

    Anon.

    2009-04-15

    Absorption and adsorption techniques make it possible to provide cold water at a typical air conditioning level by means of solar heat. Often, absorption refrigerators using lithium bromide dissolved in water as absorption agent and water as refrigerant are used for this purpose. (orig.)

  5. Absorption heat cycles. An experimental and theoretical study

    A flow sheeting programme, SHPUMP, was developed for simulating different absorption heat cycles. The programme consists of ten different modules which allow the user to construct his own absorption cycle. The ten modules configurate evaporators, absorbers, generators, rectifiers, condensers, solution heat exchangers, pumps, valves, mixers and splitters. Seven basic and well established absorption cycles are available in the configuration data base of the programme. A new Carnot model is proposed heat cycles. Together with exergy analysis, general equations for the Carnot coefficient of performance and equations for thermodynamic efficiency, exergetic efficiency and exergy index, are derived, discussed and compared for both absorption heat pumps and absorption heat transformers. Utilizing SHPUMP, simulation results are presented for different configurations where absorption heat cycles are suggested to be incorporated in three different unit operations within both pulp and paper and oleochemical industries. One of the application studies reveled that an absorption heat transformer incorporated with an evaporation plant in a major pulp and paper industry, would save 18% of the total prime energy consumption in one of the evaporation plants. It was also concluded that installing an absorption heat pump in a paper drying plant would result in steam savings equivalent to 12 MW. An experimental absorption heat transformer unit operating with self-circulation has been modified and thoroughly tested. A reference heat transformer plant has been designed and installed in a major pulp and paper mill where it is directly incorporated with one of the evaporation plants. Preliminary plant operation data are presented. 72 refs, 63 figs, 33 tabs

  6. Absorption technology for solar and waste heat utilization

    Absorption heat pumps, first developed in the 19th century, have received renewed and growing attention in the past two decades. With the increasing cost of oil and electricity, the particular features of this heat-powered cycle have made it attractive for both residential and industrial applications. Solar-powered air conditioning, gas-fired domestic cooling and waste-heat-powered temperature boosters are some of the applications on which intensive research and development has been conducted. This paper describes the operation of absorption systems and discusses several practical applications. It surveys recent advances in absorption technology, including the selection of working fluids, cycle improvements and multi-staging, and fundamentals of the combined heat and mass transfer in absorption processes. (author)

  7. Analysis of Decentralized Control for Absorption Cycle Heat Pumps

    Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard; Andersen, Palle; Pedersen, Tom Søndergård; Bendtsen, Jan Dimon

    Email Print Request Permissions This paper investigates decentralized control structures for absorption cycle heat pumps and a dynamic nonlinear model of a single-effect LiBr-water absorption system is used as case study. The model has four controllable inputs, which can be used to stabilize the...

  8. Development of solar driven absorption air conditioners and heat pumps

    Dao, K.; Wahlig, M.; Wali, E.; Rasson, J.; Molishever, E.

    1980-03-01

    The development of absorption refrigeration systems for solar active heating and cooling applications is discussed. The approaches investigated are those using air-cooled condenser-absorber and those leading to coefficient of performances (COP) that increase continuously with heat source temperature. This is primarily an experimental project, with the emphasis on designing, fabricating and testing absorption chillers in operating regimes that are particularly suited for solar energy applications. Its demonstrated that the conventional single-effect ammonia-water absorption cycle can be used (with minor modifications) for solar cooling.

  9. Application of the absorption heat pump in an oil refinery

    K.C., Sushil

    2015-01-01

    Absorption heat pumps (AHPs) have been popular due to their ability to convert thermal waste into useful energy. This study investigates the applicability of the absorption heat pump to the Porvoo oil refinery and compares the results to the ordinary heat pump (HP). The vacuum distillation unit 2 (TT2) and gas turbine (KTVL-3) units were considered for the case studies. Vacuum condenser is an inseparable part of the vacuum column DA-2201. The pressure at the top of the column DA-2201 is d...

  10. Absorption Cycle Heat Pump Model for Control Design

    Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard;

    2015-01-01

    actual heat pump located at a larger district heating plant. The model is implemented in Modelica and is based on energy and mass balances, together with thermodynamic property functions for LiBr and water and staggered grid representations for heat exchangers. Model parameters have been fitted to......Heat pumps have recently received increasing interest due to green energy initiatives and increasing energy prices. In this paper, a nonlinear dynamic model of a single-effect LiBr-water absorption cycle heat pump is derived for simulation and control design purposes. The model is based on an...

  11. Development of an Ionic-Liquid Absorption Heat Pump

    Holcomb, Don

    2011-03-29

    Solar Fueled Products (SFP) is developing an innovative ionic-liquid absorption heat pump (ILAHP). The development of an ILAHP is extremely significant, as it could result in annual savings of more than 190 billion kW h of electrical energy and $19 billion. This absorption cooler uses about 75 percent less electricity than conventional cooling and heating units. The ILAHP also has significant environmental sustainability benefits, due to reduced CO2 emissions. Phase I established the feasibility and showed the economic viability of an ILAHP with these key accomplishments: • Used the breakthrough capabilities provided by ionic liquids which overcome the key difficulties of the common absorption coolers. • Showed that the theoretical thermodynamic performance of an ILAHP is similar to existing absorption-cooling systems. • Established that the half-effect absorption cycle reduces the peak generator temperature, improving collector efficiency and reducing collector area. • Component testing demonstrated that the most critical components, absorber and generator, operate well with conventional heat exchangers. • Showed the economic viability of an ILAHP. The significant energy savings, sustainability benefits, and economic viability are compelling reasons to continue the ILAHP development.

  12. Thermodynamic modeling and performance analysis of the variable-temperature heat reservoir absorption heat pump cycle

    Qin, Xiaoyong; Chen, Lingen; Ge, Yanlin; Sun, Fengrui

    2015-10-01

    For practical absorption heat pump (AHP) plants, not all external heat reservoir heat capacities are infinite. External heat reservoir heat capacity should be an effect factor in modeling and performance analysis of AHP cycles. A variable-temperature heat reservoir AHP cycle is modeled, in which internal working substance is working in four temperature levels and all irreversibility factors are considered. The irreversibility includes heat transfer irreversibility, internal dissipation irreversibility and heat leakage irreversibility. The general equations among coefficient of performance (COP), heating load and some key characteristic parameters are obtained. The general and optimal characteristics are obtained by using numerical calculations. Besides, the influences of heat capacities of heat reservoirs, internal dissipation irreversibility, and heat leakage irreversibility on cycle performance are analyzed. The conclusions can offer some guidelines for design and operation of AHP plants.

  13. Application of customized absorption heat pumps for utilization of low-grade heat sources

    Based on established and proven technology of water/lithium bromide absorption chillers, customized single-stage and double-stage heat pump cycles adapted to specific applications can be designed, especially aiming at medium and large heating capacities of 500 kW and above. These heat pumps can either be fossil fired or driven by heat from combined heating and power (CHP) systems or other sources. In terms of primary energy saving, in many cases this is the most suitable technology to utilize the available heat sources. This is demonstrated by three examples of current installations in southern Germany. An analysis of the energetic performance and of the economic situation has been performed. At a municipal composting plant, waste heat is generated at a temperature level of about 40-50 deg. C. Previously, this waste heat had to be rejected to the ambient by means of a cooling tower. A direct-fired single-stage absorption heat pump has been installed which lifts the waste heat to a temperature level of 82 deg. C enabling its utilization in the local heating network of a commercial area. At a spa with various swimming pools located next to a thermal spring, a CHP engine plant is installed. The reject heat of the gas engine drives a novel two-stage absorption heat pump that utilizes the spring water as renewable heat source to provide heating of the pools and the building. In Munich, a solar-assisted local district heating system is installed in a new housing development area with about 300 accommodation units. At this site, a seasonal hot water storage for the solar system of about 5700 m3 is erected. At the beginning of the heating season, it serves the local heating network directly and afterwards - at a lower temperature level - it is utilized as heat source for an absorption heat pump that is driven by the municipal district heating network. By that concept two effects are accomplished: the available temperature change of the hot water storage is increased and

  14. Waste Heat Powered Ammonia Absorption Refrigeration Unit for LPG Recovery

    Donald C, Energy Concepts Co.; Lauber, Eric, Western Refining Co.

    2008-06-20

    An emerging DOE-sponsored technology has been deployed. The technology recovers light ends from a catalytic reformer plant using waste heat powered ammonia absorption refrigeration. It is deployed at the 17,000 bpd Bloomfield, New Mexico refinery of Western Refining Company. The technology recovers approximately 50,000 barrels per year of liquefied petroleum gas that was formerly being flared. The elimination of the flare also reduces CO2 emissions by 17,000 tons per year, plus tons per year reductions in NOx, CO, and VOCs. The waste heat is supplied directly to the absorption unit from the Unifiner effluent. The added cooling of that stream relieves a bottleneck formerly present due to restricted availability of cooling water. The 350oF Unifiner effluent is cooled to 260oF. The catalytic reformer vent gas is directly chilled to minus 25oF, and the FCC column overhead reflux is chilled by 25oF glycol. Notwithstanding a substantial cost overrun and schedule slippage, this project can now be considered a success: it is both profitable and highly beneficial to the environment. The capabilities of directly-integrated waste-heat powered ammonia absorption refrigeration and their benefits to the refining industry have been demonstrated.

  15. Unsteady free convection from a heated sphere in the presence of internal heat generation or absorption

    This paper is concerned with an unsteady, laminar, free convective flow over a heated sphere with the effect of internal heat generation/absorption. The dimensionless governing equations have been solved employing the finite difference method as well as a perturbation method for short time and an asymptotic method for long time. We examine the effects of the physical parameters, such as, the Prandtl number, Pr, and the heat generation/absorption parameter, γ, on the friction factor and heat transfer rate as well as the velocity and temperature profiles. It is observed that when the Prandtl number, Pr, is increased, the friction factor decreases while the heat transfer rate increases. In the presence of internal heat generation, the friction factor increases while the heat transfer rate reduces. The reverse pattern is found with the heat absorption parameter. The momentum and thermal boundary layers become thicker with an increase of the heat generation parameter. A comparison among the numerical solutions, the perturbation solutions for short time and the asymptotic solutions for long time has been presented which provides a good agreement among the solutions. (authors)

  16. System Analysis on Absorption Chiller Utilizing Intermediate Wasted Heat

    Yamada, Miki; Suzuki, Hiroshi; Usui, Hiromoto

    A system analysis has been performed for the multi-effect absorption chiller (MEAC) applied as a bottoming system of 30kW class hybrid system including micro gas turbine (MGT) and solid oxide fuel cell (SOFC) hybrid system. In this paper, an intermediate wasted heat utilization (IWHU) system is suggested for lifting up the energy efficiency of the whole system and coefficient of performance (COP) of MEAC. From the results, the suggested IWHU system was found to show the very high energy efficiency compared with a terminal wasted heat utilization (TWHU) system that uses only the heat exhausted from the terminal of MGT/SOFC system. When TWHU system is applied for MEAC, the utilized heat from the MGT/SOFC system is found to remain low because the temperature difference between the high temperature generator and the wasted heat becomes small. Then, the energy efficiency does not become high in spite of high COP of MEAC. On the other hand, the IWHU system could increase the utilized heat for MEAC as performs effectively. The exergy efficiency of IWHU system is also revealed to be higher than that of a direct gas burning system of MEAC, because the wasted heat is effectively utilized in the IWHU system.

  17. Matching heat sources cooling load and heat rejection capability with an absorption machine

    Dorgan, C.E. [Wisconsin Univ., Madison, WI (United States); Dorgan, C.B. [Dorgan Associates, Inc., Madison, WI (United States)

    1996-11-01

    The new `Application Guide for Absorption Cooling/Refrigeration Using Recovered Heat` was described. The objective of this Guide is to assist in the design and application of absorption systems by providing detailed background information and selection criteria. Topics covered include basic principles of operation, methods of heat recovery, application procedures and example selections. In this paper, the organization of the Guide was reviewed, the application procedure was presented, and two example selections were detailed. The examples correspond to a lithium bromide system and an aqueous ammonia refrigeration system. 7 refs., 2 figs., 2 tabs.

  18. A new waste heat district heating system with combined heat and power (CHP) based on ejector heat exchangers and absorption heat pumps

    A new waste heat district heating system with CHP based on ejector heat exchangers and absorption heat pumps (DH-EHE) is presented to decrease heating energy consumption of existing CHP systems by recovering waste heat of exhausted steam from a steam turbine, which could also increase heat transmission capacity of the primary heating network (PHN) by decreasing temperature of the return water of existing PHN. A new ejector heat exchanger based on ejector refrigeration cycle is invented to decrease temperature of the return water of PHN to 30 °C under the designed case. DH-EHE is analyzed in terms of laws of thermodynamics and economics. Compared to conventional district heating systems with CHP (CDH), DH-EHE can decrease consumption of steam extracted from a steam turbine by 41.4% and increase heat transmission capacity of the existing PHN by 66.7% without changing the flow rate of circulating water. The heating cost of DH-EHE is 8.62 ¥/GJ less than that of CDH. Compared to CDH, the recovery period of additional investment of DH-EHE is about two years. DH-EHE shows better economic and environmental benefits, which is promising for both district heating systems for long-distance heat transmission and waste heat district heating systems. - Highlights: • Heating capacity of this new heating system increases by 41% by waste heat recovery. • Temperature of return water of the primary heating network can be reduced to 30 °C. • Heating cost of new heating system is 8.62¥/GJ less than that of conventional one. • The recovery period of additional investment of new heating system is about 2 years. • This new heating system shows better economic and environmental benefits

  19. A new open absorption heat pump for latent heat recovery from moist gas

    Highlights: • A new open absorption heat pump system was proposed. • The new system aims at recovering latent heat from low-temperature moist gas. • The new system can utilize a lower temperature range of heat source. • COPh and heat recovery efficiency is high with the production of high-temperature steam. • Increasing generation temperature and humidity of gas is beneficial for the new system. - Abstract: Conventional drying processes discharge high humidity gas to the atmosphere. The exhaust gas contains large amount of energy. The direct discharging would result in relatively large energy waste. In order to improve the thermal efficiency of drying process, in this paper, a new open absorption heat pump system was proposed, which aims at recovering the latent heat from exhausted moist gas and producing steam for reutilization. The working principle was discussed in detail and thermodynamic models were established to analyze the performance of the new system. The new system can work under both single-stage and double-stage modes. Simulation results showed that the new system could utilize a heat source with lower generation temperature compared with that utilized by a traditional open absorption system. The temperature range of heat source for the double-stage mode is 130–160 °C, and that for the single-stage mode is 160–175 °C. The new system also eliminates the limitation of traditional close absorption system, whose evaporation temperature has to be lower than the dew point temperature of discharged moist gas to recover the latent heat of water steam. Simulation results also indicated an improved COPh of the new system compared with that of double-stage close absorption heat pump system. The COPh of the new system varied from 1.52 to 1.97 and the efficiency of heat recovery varied from 15.1% to 54.8% when the temperature of heat source varied from 135 °C to 175 °C and saturated steam of 100 °C was produced

  20. A heated chamber burner for atomic absorption spectroscopy.

    Venghiattis, A A

    1968-07-01

    A new heated chamber burner is described. The burner is of the premixed type, and burner heads of the types conventionally used in atomic absorption may be readily adapted to it. This new sampling system has been tested for Ag, Al, Ca, Cu, Fe, Mg, Mn, Ni, Pb, Si, Ti, and Zn in aqueous solutions. An improvement of the order of ten times has been obtained in sensitivity, and in detection limits as well, for the elements determined. Interferences controllable are somewhat more severe than in conventional burners but are controllable. PMID:20068792

  1. Wind power integration in Aalborg Municipality using compression heat pumps and geothermal absorption heat pumps

    Østergaard, Poul Alberg

    2013-01-01

    -temperature geothermal resources. The analyses have also demonstrated that the municipality will still rely heavily on surrounding areas for electric load balancing assistance. With a departure in a previously elaborated 100% renewable energy scenario, this article investigates how absorption heat pumps (AHP...

  2. Performance of Different Experimental Absorber Designs in Absorption Heat Pump Cycle Technologies: A Review

    Jonathan Ibarra-Bahena

    2014-02-01

    Full Text Available The absorber is a major component of absorption cycle systems, and its performance directly impacts the overall size and energy supplies of these devices. Absorption cooling and heating cycles have different absorber design requirements: in absorption cooling systems, the absorber works close to ambient temperature, therefore, the mass transfer is the most important phenomenon in order to reduce the generator size; on the other hand, in heat transformer absorption systems, is important to recover the heat delivered by exothermic reactions produced in the absorber. In this paper a review of the main experimental results of different absorber designs reported in absorption heat pump cycles is presented.

  3. Process for extracting residual heat and device for the ultimate absorption of heat for nuclear reactors

    This invention concerns a 'heat sink' or device for the ultimate absorption of heat for electric power stations using the most widespread thermal neutron nuclear reactors, namely 'light water' reactors such as boiling or pressurized water reactors. The residual heat given off by these reactors can be safely extracted with this method by using dry cooling. However, the invention does not concern the problems arising from the cooling of the steam used for actuating the steam turbine nor the cooling of the steam exhausted by the turbine or coming from it, but it does concern the 'safety' part of the nuclear power station in which the residual heat discharged in the reactor is controlled and dissipated

  4. Decay Heat Measurements Using Total Absorption Gamma-ray Spectroscopy

    Rice, S.; Valencia, E.; Algora, A.; Taín, J. L.; Regan, P. H.; Podolyák, Z.; Agramunt, J.; Gelletly, W.; Nichols, A. L.

    2012-09-01

    A knowledge of the decay heat emitted by thermal neutron-irradiated nuclear fuel is an important factor in ensuring safe reactor design and operation, spent fuel removal from the core, and subsequent storage prior to and after reprocessing, and waste disposal. Decay heat can be readily calculated from the nuclear decay properties of the fission products, actinides and their decay products as generated within the irradiated fuel. Much of the information comes from experiments performed with HPGe detectors, which often underestimate the beta feeding to states at high excitation energies. This inability to detect high-energy gamma emissions effectively results in the derivation of decay schemes that suffer from the pandemonium effect, although such a serious problem can be avoided through application of total absorption γ-ray spectroscopy (TAS). The beta decay of key radionuclei produced as a consequence of the neutron-induced fission of 235U and 239Pu are being re-assessed by means of this spectroscopic technique. A brief synopsis is given of the Valencia-Surrey (BaF2) TAS detector, and their method of operation, calibration and spectral analysis.

  5. Air source absorption heat pump in district heating: Applicability analysis and improvement options

    Highlights: • Applicability of air source absorption heat pump (ASAHP) district heating is studied. • Return temperature and energy saving rate (ESR) in various conditions are optimized. • ASAHP is more suitable for shorter distance or lower temperature district heating. • Two options can reduce the primary return temperature and improve the applicability. • The maximum ESR is improved from 13.6% to 20.4–25.6% by compression-assisted ASAHP. - Abstract: The low-temperature district heating system based on the air source absorption heat pump (ASAHP) was assessed to have great energy saving potential. However, this system may require smaller temperature drop leading to higher pump consumption for long-distance distribution. Therefore, the applicability of ASAHP-based district heating system is analyzed for different primary return temperatures, pipeline distances, pipeline resistances, supplied water temperatures, application regions, and working fluids. The energy saving rate (ESR) under different conditions are calculated, considering both the ASAHP efficiency and the distribution consumption. Results show that ASAHP system is more suitable for short-distance district heating, while for longer-distance heating, lower supplied hot water temperature is preferred. In addition, the advantages of NH3/H2O are inferior to those of NH3/LiNO3, and the advantages for warmer regions and lower pipeline resistance are more obvious. The primary return temperatures are optimized to obtain maximum ESRs, after which the suitable distances under different acceptable ESRs are summarized. To improve the applicability of ASAHP, the integration of cascaded heat exchanger (CHX) and compression-assisted ASAHP (CASAHP) are proposed, which can reduce the primary return temperature. The integration of CHX can effectively improve the applicability of ASAHP under higher supplied water temperatures. As for the utilization of CASAHP, higher compression ratio (CR) is better in longer

  6. ASHRAE`s new application guide for absorption cooling/refrigeration using recovered heat

    Dorgan, C.B.; Dorgan, C.E.; Leight, S.P. [Dorgan Associates, Inc., Madison, WI (United States)

    1995-12-31

    ASHRAE has a new publication, Application Guide for Absorption Cooling/Refrigeration Using Recovered Heat. This guide is a comprehensive reference manual for the application of indirect-fired absorption machines. An indirect-fired absorption machine uses heat recovered from another process or heat cycle machine versus a direct-fired absorption machine, which uses a primary fuel source. The Guide is designed to help engineers, owners, developers, and marketing personnel to become familiar with the requirements of an absorption system, evaluate indirect-fired absorption machines for specific requirements, evaluate the potential of available recovered heat sources, select the most economical system, and understand both lithium bromide (LiBr) and ammonia absorption machines. The Guide provides information on the application and economics of absorption machines. Detailed design of an absorption system is covered in other publications, which are listed in the Guide. The Guide introduces absorption technology through comparison with and using the terminology of vapor-compression technology. This information is then expanded to enable the reader to apply absorption technology to many situations where recovered heat is available.

  7. Coefficient of Performance Optimization of Single-Effect Lithium-Bromide Absorption Cycle Heat Pumps

    Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard; Andersen, Palle; Pedersen, Tom Søndergård; Bendtsen, Jan Dimon

    In this paper, we investigate the coefficient of performance (COP) of a LiBr absorption cycle heat pump under different operating conditions. The investigation is carried out using a dynamical model fitted against data recorded from an actual heat pump used for district heating in S⊘nderborg, Den......In this paper, we investigate the coefficient of performance (COP) of a LiBr absorption cycle heat pump under different operating conditions. The investigation is carried out using a dynamical model fitted against data recorded from an actual heat pump used for district heating in S...

  8. HEAT TRANSFORMATION IN THE PLANT FOR INTEGRATED ENERGY SUPPLY BY LITHIUM BROMIDE ABSORPTION MACHINE

    А.М. Радченко; Остапенко, О. В.

    2015-01-01

    The efficiency of waste heat transformation from gas engines in the plant forintegratedenergysupply by lithium bromideabsorption refrigerating machine was analyzed. Such gas engines are equipped with heat exchangers for producing hot water from the engine recoverable heat. The waste heat from gas engine jacket and lubricant oil cooling water, scavenge gas-air mixture and exhaust gas are used to produce hot water with the temperature of about 90 °С as heating source for absorption chiller. The...

  9. Evaluation of a seasonal storage system of solar energy for house heating using different absorption couples

    Research highlights: → An absorption system for long-term energy storage for house heating is presented. → The storage capacity and efficiency of seven absorption couples are studied. → The influence of temperature of absorption, evaporation and storage is evaluated. → The appearance of crystals in the storage tank increases the storage capacity. -- Abstract: In this paper, an innovative concept is presented for a long-term energy storage system for house heating, using the absorption process. The solar energy is stored during summer through desorption and the heat is released during winter through absorption. The originality of this concept is to allow the solution to reach the crystallization point, which is usually avoided in the absorption refrigeration machines. The storage capacity and efficiency of seven absorption couples, CaCl2/H2O, Glycerin/H2O, KOH/H2O, LiBr/H2O, LiCl/H2O, NaOH/H2O and H2O/NH3, as a function of the temperature of absorption, temperature of evaporation, temperature of the solution before absorption and the presence of crystals in the storage tank have been studied in this paper. The appearance of crystals increases the storage capacity. The storage capacity increases with the temperature of evaporation and the temperature of the solution before absorption but decreases with the temperature of absorption.

  10. Evaluation of a seasonal storage system of solar energy for house heating using different absorption couples

    Liu Hui, E-mail: hui.liu@univ-savoie.f [LOCIE, CNRS UMR 5271-Universite de Savoie, Polytech' Savoie, Campus Scientifique, Savoie Technolac, 73376 Le Bourget-Du-Lac Cedex (France); Edem, N' Tsoukpoe K., E-mail: Kokouvi-Edem.N-Tsoukpoe@univ-savoie.f [LOCIE, CNRS UMR 5271-Universite de Savoie, Polytech' Savoie, Campus Scientifique, Savoie Technolac, 73376 Le Bourget-Du-Lac Cedex (France); Nolwenn, Le Pierres, E-mail: nolwenn.le-pierres@univ-savoie.f [LOCIE, CNRS UMR 5271-Universite de Savoie, Polytech' Savoie, Campus Scientifique, Savoie Technolac, 73376 Le Bourget-Du-Lac Cedex (France); Luo Lingai, E-mail: lingai.luo@univ-savoie.f [LOCIE, CNRS UMR 5271-Universite de Savoie, Polytech' Savoie, Campus Scientifique, Savoie Technolac, 73376 Le Bourget-Du-Lac Cedex (France)

    2011-06-15

    Research highlights: {yields} An absorption system for long-term energy storage for house heating is presented. {yields} The storage capacity and efficiency of seven absorption couples are studied. {yields} The influence of temperature of absorption, evaporation and storage is evaluated. {yields} The appearance of crystals in the storage tank increases the storage capacity. -- Abstract: In this paper, an innovative concept is presented for a long-term energy storage system for house heating, using the absorption process. The solar energy is stored during summer through desorption and the heat is released during winter through absorption. The originality of this concept is to allow the solution to reach the crystallization point, which is usually avoided in the absorption refrigeration machines. The storage capacity and efficiency of seven absorption couples, CaCl{sub 2}/H{sub 2}O, Glycerin/H{sub 2}O, KOH/H{sub 2}O, LiBr/H{sub 2}O, LiCl/H{sub 2}O, NaOH/H{sub 2}O and H{sub 2}O/NH{sub 3}, as a function of the temperature of absorption, temperature of evaporation, temperature of the solution before absorption and the presence of crystals in the storage tank have been studied in this paper. The appearance of crystals increases the storage capacity. The storage capacity increases with the temperature of evaporation and the temperature of the solution before absorption but decreases with the temperature of absorption.

  11. INVESTIGATION OF SOLAR ABSORPTANCE OF BUILDING EXTERNAL SURFACES FROM HEAT FLUX POINT OF VIEW

    Meral ÖZEL

    2006-02-01

    Full Text Available In this study, solar absorptance of external surfaces of buildings has been numerically investigated from the heat gain and losses point of view. For this purpose, external surface solar absorptance was icreased from 0 to 1with an ratio of 0.1 and, for the summer and winter conditions, heat fluxs was calculated by considering orientations of the wall and its roof for brick and concrete structure materials. Besides, external surface absorptance was assumed as 0.2, 0.5 and 0.9, respectively. Than, heat gain and losses were calculated to insulation thickness increasing on the outdoor surface of wall. Results obtained were presented as graphics

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

    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 ze......, all with economical benefits for the investor....

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

    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 phas...... up to 60 K, all with economical benefits for the investor....

  14. Thermo-ecological analysis and optimization performance of an irreversible three-heat-source absorption heat pump

    Highlights: • Thermo-ecological modeling of irreversible three-heat-source absorption heat pump is performed. • The latter is achieved using NSGA algorithm and thermodynamic analysis. • Various decision makers are carried out to indicate optimum values of outputs obtained with optimization process. - Abstract: Throughout present research, optimization investigations of an irreversible absorption heat pump system on the basis of a new thermo-ecological criterion. The objective functions which considered are the specific heating load, coefficient of performance (COP) and the ecological coefficient of performance (ECOP). Three objective functions of the ECOP, COP and the specific heating load are optimized simultaneously using the multi-objective optimization algorithm NSGAII. COP and ECOP are maximized and specific heating load is minimized in order to get the best performance. Decision making is done by means of three methods of LINAMP and TOPSIS and FUZZY. Finally, sensitivity analysis and error analysis was performed for the system

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

    Jensen, Jonas Kjær; Ommen, Torben Schmidt; Markussen, Wiebke Brix; Reinholdt, L.; Elmegaard, Brian

    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 base...

  16. Optimal Cooling Load and COP Relationship of a Four-Heat-Reservoir Endoreversible Absorption Refrigeration Cycle

    Chih Wu; Fengrui Sun; Tong Zheng; Lingen Chen

    2004-01-01

    Abstract: On the basis of a four-heat-reservoir endoreversible absorption refrigeration cycle model, another linear heat transfer law [i.e., the heat-flux] is adopted, the fundamental optimal relation between the coefficient of performance (COP) and the cooling load, as well as the maximum cooling load and the corresponding COP of the cycle coupled to constant-temperature heat reservoirs are derived by using finite-time thermodynamics or thermodynamic optimization. The optimal distribution of...

  17. ASHRAE`s new application guide for absorption cooling/refrigeration using recovered heat

    Dorgan, C.B.; Dorgan, C.E.; Leight, S.P. [Dorgan Associates Inc., Madison, WI (United States)

    1995-07-01

    This article is a brief overview of the Guide for Absorption Cooling/Refrigeration Using Recovered Heat. The overview examines the applications of the guide, it`s format and topics on a chapter basis. The authors report that ASHRAE`s purpose for developing this manual is to encourage more engineers and owners to consider using recovered heat for cooling and refrigeration.

  18. SOLAR MULTI-STAGE ABSORPTION REFRIGERATION SYSTEMS BASED ON FILM TYPE HEAT-MASS EXCHANGE APPARATUSES

    Дорошенко, О.В.; Антонова, А.Р.; Людницький, К.В.

    2015-01-01

    The paper presents the developed circuit solutions for alternative refrigeration systems based on the of heat-absorption cycle and solar energy utilization for regeneration (recovery) of the absorbent solution. Cascade principle of heat-mass exchange apparatuses construction was applied, of drying and cooling loops with varying of  temperature level and increasing  of absorbent concentration on the cascade steps. Film type heat and mass transfer equipment, which is the part of the drying and ...

  19. Crystallization Analysis and Control of Ammonia-Based Air Source Absorption Heat Pump in Cold Regions

    Wu, Wei; Wang, Baolong; Shi, Wenxing; Li, Xianting

    2013-01-01

    Energy consumption of heating and domestic hot water is very high and will keep increasing. Air source absorption heat pump (ASAHP) was proposed to overcome the problems of low energy efficiency and high air pollution existing in boiler systems, as well as the problem of bad performance under low ambient temperatures for electrical heat pumps. In order to investigate the crystallization possibility of ammonia-salt ASAHP, crystallization margin (evaluated by solution mass concentration) at gen...

  20. New configurations of a heat recovery absorption heat pump integrated with a natural gas boiler for boiler efficiency improvement

    Highlights: • Thermal and heat transfer models of absorption heat pumps driven by exhaust gas, hot water, or natural gas. • Natural gas boiler combustion model. • Heat exchanger for condensing. • Experimental data of a hot water absorption heat pump. • Economic assessment of heat recovery absorption heat pump for improving natural gas boilers. - Abstract: Conventional natural gas-fired boilers exhaust flue gas direct to the atmosphere at 150–200 °C, which, at such temperatures, contains large amount of energy and results in relatively low thermal efficiency ranging from 70% to 80%. Although condensing boilers for recovering the heat in the flue gas have been developed over the past 40 years, their present market share is still less than 25%. The major reason for this relatively slow acceptance is the limited improvement in the thermal efficiency of condensing boilers. In the condensing boiler, the temperature of the hot water return at the range of 50–60 °C, which is used to cool the flue gas, is very close to the dew point of the water vapor in the flue gas. Therefore, the latent heat, the majority of the waste heat in the flue gas, which is contained in the water vapor, cannot be recovered. This paper presents a new approach to improve boiler thermal efficiency by integrating absorption heat pumps with natural gas boilers for waste heat recovery (HRAHP). Three configurations of HRAHPs are introduced and discussed. The three configurations are modeled in detail to illustrate the significant thermal efficiency improvement they attain. Further, for conceptual proof and validation, an existing hot water-driven absorption chiller is operated as a heat pump at operating conditions similar to one of the devised configurations. An overall system performance and economic analysis are provided for decision-making and as evidence of the potential benefits. These three configurations of HRAHP provide a pathway to achieving realistic high-efficiency natural

  1. Multifunctional absorption technology in district heating systems; Absorptionsteknik med multifunktion i fjaerrvaermesystem

    Martin, Viktoria; Setterwall, Fredrik

    2010-05-15

    Within the framework of the IEA's implementing agreement on heat pumping technologies, a state-of-the-art assessment of absorption technology was presented the year 2000. There, barriers for increased implementation of absorption technology were pointed out as being the high investment cost, as well as lack of knowledge with engineers and other actors. The project presented herein has analyzed the situation ten years later, with a wide scope of using the absorption technology - from ice to steam production in a district energy system. The overall aim of the presented project is to provide new knowledge on the technical and economical possibilities of integrating multiple function absorption technology in district energy systems. Also, new knowledge on important design parameters for practical and cost-effective design is given, for example the influence of temperatures (heat source as well as heat sink) and desired COP. A combination of renewed state-of-the-art assessment and new calculations has been used to reach this goal. The state-of-the-art assessment show that the increased focus on combined heat and power (CHP) for resource-efficient energy conversion go hand in hand with an increased interest in thermally driven cooling (TDC) technology. This project has identified the following to be specifically district energy adapted in absorption cooling: - design for low return temperature of the heat carrier leaving the generator part - design for 'high enough' COP maintained at part load for heat source temperatures as low as 70 deg C. - cost minimization by optimal sizing of heat exchanger surfaces for district energy design criteria (as opposed to accepting 'off-the-shelf' designs intended for higher operating temperatures). The overall analysis and findings regarding trigeneration concludes that: a. a holistic view of the production of power, heat and cold should be adopted when considering absorption technology in district energy

  2. Investigation of ammonia/water hybrid absorption/compression heat pumps for heat supply temperatures above 100 °C

    Jensen, Jonas Kjær; Reinholdt, Lars; Markussen, Wiebke Brix; Elmegaard, Brian

    2014-01-01

    The hybrid absorption/compression heat pump (HACHP) using ammonia-water as working fluid is a promising technology for development of a high temperature industrial heat pump. This is due to two properties inherent to the use of zeotropic mixtures: non-isothermal phase change and reduced vapour pressures. Using standard refrigeration components (28 bar) HACHP up to 100 °C are commercially available. Components developed for high pressure NH3 (52 bar) and transcritical CO2 (140 bar) increase th...

  3. Optimal Cooling Load and COP Relationship of a Four-Heat-Reservoir Endoreversible Absorption Refrigeration Cycle

    Chih Wu

    2004-06-01

    Full Text Available Abstract: On the basis of a four-heat-reservoir endoreversible absorption refrigeration cycle model, another linear heat transfer law [i.e., the heat-flux] is adopted, the fundamental optimal relation between the coefficient of performance (COP and the cooling load, as well as the maximum cooling load and the corresponding COP of the cycle coupled to constant-temperature heat reservoirs are derived by using finite-time thermodynamics or thermodynamic optimization. The optimal distribution of the heat-transfer surface areas is also obtained. Moreover, the effects of the cycle parameters on the COP and the cooling load of the cycle are studied by detailed numerical examples. The results obtained herein are of importance to the optimal design and performance improvement of an absorption refrigeration cycle.

  4. Thermo-economic analysis of steady state waste heat recovery in data centers using absorption refrigeration

    Highlights: • Absorption refrigeration is powered by data center waste heat. • Waste heat from 3 to 5 server racks produces cooling for an additional rack. • An economic analysis shows the payback period can be as short as 4–5 months. - Abstract: This paper addresses the technical and economic issues associated with waste heat recovery in data centers through the use of absorption cooling machines. The theoretical possibility of utilizing the heat dissipated by a server, or a number of servers, to power an absorption system, which in turn produces cooling for other servers in the data center, is investigated. For this purpose, a steady-state thermodynamic model is developed to perform energy balance and exergy analyses for a novel configuration of an on-chip two-phase cooling system and an absorption refrigeration system. This combination is created by replacing the condenser in the on-chip cooling circuit with the generator of an absorption refrigeration cycle. The performance of the developed model in simulating both LiBr–water and water–ammonia absorption cooling systems is examined through verification of the model results against the reference data available in the literature. The verification indicates the superiority of LiBr–water absorption system for data center/server operating conditions. Therefore, a LiBr–water absorption refrigeration system is modeled in the novel combined heat recovery system. For these systems it is shown that the traditional definition for the coefficient of performance (COP) is not appropriate to evaluate the performance and, in its place, introduce a new figure of merit. Through a sensitivity analysis, the effects of server waste heat quality, server coolant type, solution peak concentration, solution heat exchanger effectiveness, evaporator temperature, and operating pressures on the performance of the novel system are investigated. Finally, using the thermodynamic model and cost information provided by the

  5. Measurement of XUV-absorption spectra of ZnS radiatively heated foils

    Kontogiannopoulmos, Nikolaos; Thais, Frédéric; Chenais-Popovics, Claude; Sauvan, Pascal; Schott, R; Fölsner, Wolfgang; Arnault, Philippe; Poirier, Michel; Blenski, Thomas

    2008-01-01

    Time-resolved absorption of zinc sulfide (ZnS) and aluminum in the XUV-range has been measured. Thin foils in conditions close to local thermodynamic equilibrium were heated by radiation from laser-irradiated gold spherical cavities. Analysis of the aluminum foil radiative hydrodynamic expansion, based on the detailed atomic calculations of its absorption spectra, showed that the cavity emitted flux that heated the absorption foils corresponds to a radiation temperature in the range 55 60 eV. Comparison of the ZnS absorption spectra with calculations based on a superconfiguration approach identified the presence of species Zn6+ - Zn8+ and S5+ - S6+. Based on the validation of the radiative source simulations, experimental spectra were then compared to calculations performed by post-processing the radiative hydrodynamic simulations of ZnS. Satisfying agreement is found when temperature gradients are accounted for.

  6. Investigation of ammonia/water hybrid absorption/compression heat pumps for heat supply temperatures above 100 °C

    Jensen, Jonas Kjær; Reinholdt, Lars; Markussen, Wiebke Brix;

    2014-01-01

    using these components. A technically and economically feasible solution is defined as one that satisfies constraints on the coefficient of performance (COP), low and high pressure, compressor discharge temperature and volumetric heat capacity. The ammonia mass fraction of the rich solution......The hybrid absorption/compression heat pump (HACHP) using ammonia-water as working fluid is a promising technology for development of a high temperature industrial heat pump. This is due to two properties inherent to the use of zeotropic mixtures: non-isothermal phase change and reduced vapour...

  7. Heat of Absorption of CO2 in Aqueous Solutions of DEEA, MAPA and their Mixture

    Waseem Arshad, Muhammad; von Solms, Nicolas; Thomsen, Kaj;

    2013-01-01

    A reaction calorimeter was used to measure the differential heat of absorption of CO2 in phase change solvents as a function of temperature, CO2 loading and solvent composition. The measurements were taken for aqueous solutions of 2-(diethylamino)ethanol (DEEA), 3-(methylamino)propylamine (MAPA......) and their mixture. The tested compositions were 5M DEEA, 2M MAPA and their mixture, 5M DEEA + 2M MAPA which gives two liquid phases on reacting with CO2. Experimental measurements were also carried out for 30% MEA used as a base case. The measurements were taken isothermally at three different...... temperatures 40, 80 and 120°C at a CO2 feed pressure of 600kPa. In single aqueous amine solutions, heat of absorption increases with increase in temperature and depends on thetype of amine used. DEEA, a tertiary amine, has lower heat of absorption compared to MAPA being a diamine with primary and secondary...

  8. A new heating system based on coupled air source absorption heat pump for cold regions: Energy saving analysis

    Highlights: • A double-stage coupled air source absorption heat pump (ASAHP) is proposed. • The coupled ASAHP exhibits stable and high performance in very cold regions. • Energy-saving rate of the coupled ASAHP in all the typical cities is above 20%. - Abstract: Energy consumption for heating and domestic hot water is very high. The heating system based on an air source absorption heat pump (ASAHP) had been assessed to have great energy saving potential. However, the single-stage ASAHP exhibits poor performance when the outdoor air temperature is very low. A double-stage coupled ASAHP is proposed to improve the energy-saving potential of single-stage ASAHP in cold regions. The heating capacity and primary energy efficiency (PEE) of the proposed system operated in both coupled mode and single-stage mode are simulated under various working conditions. The building load and primary energy consumption of different heating systems applied in cold regions are analyzed comparatively to investigate the energy-saving potential of the coupled ASAHP. Results show that the coupled ASAHP exhibits stable PEE and provides high heating capacity in very cold conditions. The energy-saving rate of the coupled ASAHP in all the typical cities is above 20%. In addition, the energy-saving potential of the single-stage ASAHP in severely cold areas can be improved obviously by coupled ASAHP, with an improvement of 7.73% in Harbin

  9. Thermo-economic optimization of an endoreversible four-heat-reservoir absorption-refrigerator

    Based on an endoreversible four-heat-reservoir absorption-refrigeration-cycle model, the optimal thermo-economic performance of an absorption-refrigerator is analyzed and optimized assuming a linear (Newtonian) heat-transfer law applies. The optimal relation between the thermo-economic criterion and the coefficient of performance (COP), the maximum thermo-economic criterion, and the COP and specific cooling load for the maximum thermo-economic criterion of the cycle are derived using finite-time thermodynamics. Moreover, the effects of the cycle parameters on the thermo-economic performance of the cycle are studied by numerical examples

  10. The Effect of Heat on Structural Characteristics and Water Absorption Behavior of Agave Fibers

    Saikia, Dip

    2008-04-01

    The structural characteristics and water absorptions behavior agave fibers were investigated over a range of temperature by using XRD, IR, TG and gravimetric methods. Three distinct thermal processes were observed during heating the fiber in the temperature range 310-760 K in air, oxygen and nitrogen invariably. The cellulose structures of the fibers were unaffected on heating up to 450 K. The samples showed thermal decomposition processes beyond 500 K. Fibers displayed a two-stage diffusion behavior. The structural parameters and kinetic of water absorption of the fibers at specific temperatures were analyzed.

  11. Automotive absorption air conditioner utilizing solar and motor waste heat

    Popinski, Z. (Inventor)

    1981-01-01

    In combination with the ground vehicles powered by a waste heat generating electric motor, a cooling system including a generator for driving off refrigerant vapor from a strong refrigerant absorbant solution is described. A solar collector, an air-cooled condenser connected with the generator for converting the refrigerant vapor to its liquid state, an air cooled evaporator connected with the condenser for returning the liquid refrigerant to its vapor state, and an absorber is connected to the generator and to the evaporator for dissolving the refrigerant vapor in the weak refrigerant absorbant solution, for providing a strong refrigerant solution. A pump is used to establish a pressurized flow of strong refrigerant absorbant solution from the absorber through the electric motor, and to the collector.

  12. Application of waste heat powered absorption refrigeration system to the LNG recovery process

    Kalinowski, Paul; Hwang, Yunho; Radermacher, Reinhard [Center for Environmental Energy Engineering, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742 (United States); Al Hashimi, Saleh; Rodgers, Peter [The Petroleum Institute, Abu Dhabi (United Arab Emirates)

    2009-06-15

    The recovery process of the liquefied natural gas requires low temperature cooling, which is typically provided by the vapor compression refrigeration systems. The usage of an absorption refrigeration system powered by waste heat from the electric power generating gas turbine could provide the necessary cooling at reduced overall energy consumption. In this study, a potential replacement of propane chillers with absorption refrigeration systems was theoretically analyzed. From the analysis, it was found that recovering waste heat from a 9 megawatts (MW) electricity generation process could provide 5.2 MW waste heat produced additional cooling to the LNG plant and save 1.9 MW of electricity consumption. Application of the integrated cooling, heating, and power is an excellent energy saving option for the oil and gas industry. (author)

  13. Comparison of LCA results of low temperature heat plant using electric heat pump, absorption heat pump and gas-fired boiler

    Highlights: • Usage of geothermal heat pump can bring environmental benefits. • The lowest environmental impact for whole life cycle is obtained for absorption heat pump. • The value of heat pump COP has a significant influence on environmental impact. • In case of coal based power generation the damage to human health is significant. - Abstract: This study compares the life cycle impacts of three heating plant systems which differ in their source of energy and the type of system. The following heating systems are considered: electric water-water heat pump, absorption water-water heat pump and natural gas fired boiler. The heat source for heat pump systems is low temperature geothermal source with temperature below 20 °C and spontaneous outflow 24 m3/h. It is assumed that the heat pumps and boiler are working in monovalent system. The analysis was carried out for heat networks temperature characteristic at 50/40 °C which is changing with outdoor temperature during heating season. The environmental life cycle impact is evaluated within life cycle assessment methodological framework. The method used for life cycle assessment is eco-indicator ‘99. The functional unit is defined as heating plant system with given amount of heat to be delivered to meet local heat demand in assumed average season. The data describing heating plant system is derived from literature and energy analysis of these systems. The data describing the preceding life cycle phases: extraction of raw materials and fuels, production of heating devices and their transportation is taken from Ecoinvent 2.0 life cycle inventory database. The results were analyzed on three levels of indicators: single score indicator, damage category indicators and impact category indicator. The indicators were calculated for characterization, normalization and weighting phases as well. SimaPro 7.3.2 is the software used to model the systems’ life cycle. The study shows that heating plants using a low

  14. MHD Free Convection from an Isothermal Truncated Cone with Variable Viscosity and Internal Heat Generation (Absorption)

    A.H.Srinivasa,; A.T. Eswara

    2016-01-01

    This paper presents a study of MHD free convection flow of an electrically conducting incompressible fluid with variable viscosity about an isothermal truncated cone in the presence of heat generation or absorption. The fluid viscosity is assumed to vary as a inverse linear function of temperature. The non-linear coupled partial differential equations governing the flow and heat transfer have been solved numerically by using an implicit finite - difference scheme along with quasil...

  15. Development of whole energy absorption spectrometer for decay heat measurement on fusion reactor materials

    Maekawa, Fujio; Ikeda, Yujiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    To measure decay heat on fusion reactor materials irradiated by D-T neutrons, a Whole Energy Absorption Spectrometer (WEAS) consisting of a pair of large BGO (bismuth-germanate) scintillators was developed. Feasibility of decay heat measurement with WEAS for various materials and for a wide range of half-lives (seconds - years) was demonstrated by experiments at FNS. Features of WEAS, such as high sensitivity, radioactivity identification, and reasonably low experimental uncertainty of {approx} 10 %, were found. (author)

  16. Absorption coefficient measurements of particle-laden filters using laser heating: Validation with nigrosin

    A laser-heating technique, referred as the laser-driven thermal reactor, was used in conjunction with laser transmissivity measurements to determine the absorption coefficient of particle-laden substrates (e.g., quartz-fiber filters). The novelty of this approach is that it analyzes a wide variety of specific samples (not just filtered samples) and overcomes measurement issues (e.g., absorption enhancement) associated with other filter-based particle absorption techniques. The absorption coefficient was determined for nigrosin-laden, quartz-fiber filters and the effect of the filter on the absorption measurements was estimated when compared to the isolated nigrosin results. The isolated nigrosin absorption coefficient compared favorably with Lorenz-Mie calculations for an idealized polydispersion of spherical particles (based on a measured nigronsin/de-ionized water suspension size distribution) dispersed throughout a volume equivalent to that of the nigrosin-laden filter. To validate the approach, the absorption coefficient of a nigrosin/de-ionized water suspension was in good agreement with results obtained from an ultraviolet/visible spectrometer. In addition, the estimated imaginary part of the refractive index from the Lorenz-Mie calculations compared well with literature values and was used to estimate the absorption coefficient of optically opaque packed nigrosin.

  17. A Parametric Analysis of CO2 Laser Heat Absorption Profile of 5083 Aluminum Alloy

    JOSEPH .I. ACHEBO

    2010-06-01

    Full Text Available Aluminum alloys are amongst the most difficult everyday metals that can be welded using the laser welding process. For this reason, high power density lasers are needed to weld these alloys because they require higher thermal diffusivity to form a key hole than would be needed for other metals such as steel. This means that more heat wouldhave to be applied while welding aluminum alloys than would be needed to weld steel to achieve a satisfactory coupling effect. The heat input generated from laser welding is affected by the absorptivity coefficient, the welding speed and the time spent. Once the optimum heat input is attained, it is expected to create less heat distortion, its energy is more concentrated within the weld area and deep weld penetration is achieved. Determining optimum values of welding parameters would lead to acceptable weld quality. In this study, the heat absorption profile of a CO2 laser welding of 5083 aluminum alloy was investigated using the models proposed by Bramson in 1968 and Okon et al in 2002. The 4mm thick aluminum alloy investigated was as received from the vendors. The calculated laser beam absorptivity coefficient, irradiance and boiling temperature were 0.12, 2.3 x 106 Wcm-2 and 2482oC respectively. These calculated values compared well with reported values in other literature.

  18. Performance analysis on a new multi-effect distillation combined with an open absorption heat transformer driven by waste heat

    In this paper, a new water distillation system, which consists of either a single- or multi-effect distiller combined with an open absorption heat transformer (OAHT), has been proposed. The new integrated system can be used for distilling waste water with high amounts of SiO2 from heavy oil production, and the resultant distilled water can be supplied to steam boilers to produce high quality steam which in turn is injected into oil reservoirs to assist with heavy oil recovery. The thermodynamic cycle performances for these new integrated distillation systems were simulated based on the thermodynamic properties of the aqueous solution of LiBr as well as the mass and energy balance of the system. The results indicate that combined with OAHT, the waste heat at 70 °C can be elevated to 125 °C and thereby produce steam at 120 °C in the absorber, which is able to drive a four-effect distiller to produce distilled water. For a single-effect and four-effect distiller, the coefficients of performance (COP) are approximately 1.02 while the performance ratios are 2.19 and 5.72, respectively. Therefore, the four-effect distillation system combined with an OAHT is more thermally effective and is an ideal option to process the waste water in oilfields. -- Highlights: • A new absorption vapor compression distillation was proposed in present research. • An open absorption heat transformer has a coupled thermally evaporator and absorber. • Distillation of waste water with high content of SiO2 from heavy oil production. • The waste heat of 70 °C can be elevated up to 125 °C and generate steam of 120 °C. • The waste heat is able to drive four-effect distillation to produce distilled water

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

    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. New configurations of a heat recovery absorption heat pump integrated with a natural gas boiler for boiler efficiency improvement

    Qu, Ming [Purdue University, West Lafayette, IN; Abdelaziz, Omar [ORNL; Yin, Hongxi [Southeast University, Nanjing, China

    2014-11-01

    Conventional natural gas-fired boilers exhaust flue gas direct to the atmosphere at 150 200 C, which, at such temperatures, contains large amount of energy and results in relatively low thermal efficiency ranging from 70% to 80%. Although condensing boilers for recovering the heat in the flue gas have been developed over the past 40 years, their present market share is still less than 25%. The major reason for this relatively slow acceptance is the limited improvement in the thermal efficiency of condensing boilers. In the condensing boiler, the temperature of the hot water return at the range of 50 60 C, which is used to cool the flue gas, is very close to the dew point of the water vapor in the flue gas. Therefore, the latent heat, the majority of the waste heat in the flue gas, which is contained in the water vapor, cannot be recovered. This paper presents a new approach to improve boiler thermal efficiency by integrating absorption heat pumps with natural gas boilers for waste heat recovery (HRAHP). Three configurations of HRAHPs are introduced and discussed. The three configurations are modeled in detail to illustrate the significant thermal efficiency improvement they attain. Further, for conceptual proof and validation, an existing hot water-driven absorption chiller is operated as a heat pump at operating conditions similar to one of the devised configurations. An overall system performance and economic analysis are provided for decision-making and as evidence of the potential benefits. These three configurations of HRAHP provide a pathway to achieving realistic high-efficiency natural gas boilers for applications with process fluid return temperatures higher than or close to the dew point of the water vapor in the flue gas.

  1. Optical absorption and radiative heat transport in olivine at high temperature

    The optical absorption spectra of natural single-crystal and polycrystalline olivine (mg/sub 1.84/Fe/sub 0.16/SiO4) have been measured in the wavelength range 300--8000 nm at temperatures ranging from 300 to 1700 K and under oxygen fugacity well within the sample stability field. The absorption significantly increases with increasing temperature due to a regular broadening of both crystal field and multiphonon lattice vibrational absorption bands; these are the principal absorption bands in the spectral region involved in radiative heat transfer. In the 'window' region between these bands the absorption coefficient increases from near zero at 300 K to about 10--15 cm-1 at 1700 K. Under mantle conditions the radiative thermal conductivity (K/sub R/) calculated from the olivine single-crystal spectra increases from near zero at 300 K to about 5 x 10-3 cal/cm s K (2W/m K) at 1700 K and is only weakly dependent on temperature above 800 K. Our determination of K/sub R/ is 10--20% lower than previous estimates based on absorption measurements under different experimental conditions. In polycrystalline (dunite) samples the transmission decreased substantially with temperature cycling due to scattering at intergranular interfaces created by differential thermal expansion

  2. Application of customized absorption heat pumps with heating capacities above 500 kW

    Radspieler, Michael; Zachmeier, Peter; Schweigler, Christian

    2013-01-01

    Part of: Thermally driven heat pumps for heating and cooling. – Ed.: Annett Kühn – Berlin: Universitätsverlag der TU Berlin, 2013 ISBN 978-3-7983-2686-6 (print) ISBN 978-3-7983-2596-8 (online) urn:nbn:de:kobv:83-opus4-39458 [http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-39458

  3. On the development of high temperature ammonia-water hybrid absorption-compression heat pumps

    Jensen, Jonas Kjær; Markussen, Wiebke Brix; Reinholdt, Lars;

    2015-01-01

    and volumetric heat capacity. The ammonia mass fraction and the liquid circulation ratio both influence these constraining parameters. The paper investigates feasible combinations of these parameters through the use of a numerical model. 28 bar components allow temperatures up to 111 °C, 50 bar up to 129°C......Ammonia-water hybrid absorption-compression heat pumps (HACHP) are a promising technology for development of ecient high temperature industrial heat pumps. Using 28 bar components HACHPs up to 100 °C are commercially available. Components developed for 50 bar and 140 bar show that these pressure...... limits may be possible to exceed if needed for actual applications. Feasible heat supply temperatures using these component limits are investigated. A feasible solution is defined as one that satisfies constraints on the COP, low and high pressure, compressor discharge temperature, vapour water content...

  4. Performance of hybrid quad generation system consisting of solid oxide fuel cell system and absorption heat pump

    Cachorro, Irene Albacete; Daraban, Iulia Maria; Lainé, Guillaume;

    2013-01-01

    . The heat pump is a heat driven system and is running with the heat recovered by a heat exchanger from the exhausted gases from SOFC. The working fluid pair is NH3-H2O and is driven in two evaporators which are working at two different pressures. Thus, the heat pump will operate at tree pressure level......In this paper a system consisting of an SOFC system for cogeneration of heat and power and vapour absorption heat pump for cooling and freezing is assessed and performance is evaluated. Food industry where demand includes four forms of energy simultaneously is a relevant application such a system...... in order to meet the bought cooling and freezing demands. This is an innovative configuration for absorption heat pumps because the cascade is implemented only in vapour compression heat pumps. A smaller ratio of the exhausted gases supplies the energy demand for space heating. The SOFC is fuelled...

  5. Simulation and experimental study of solar-absorption heat transformer integrating with two-stage high temperature vapor compression heat pump

    Nattaporn Chaiyat; Tanongkiat Kiatsiriroat

    2014-01-01

    In this study, simulation and experiment studies of a 10 kW solar H2O–LiBr absorption heat transformer (AHT) integrating with a two-stage vapor compression heat pump (VCHP) were carried out. The whole system was named as compression/absorption heat transformer (CAHT). The VCHP was used to recover rejected heat at the AHT condenser which was transferred back to the AHT evaporator at a higher temperature. The AHT unit took solar heat from a set of flat-plate solar collectors in parallel connect...

  6. Slip Effect on MHD Chemically Reacting Convictive Boundary Layer Flow with Heat Absorption

    Mekonnen Shifferaw Ayano

    2016-01-01

    Full Text Available The aim of this paper is to investigate steady magneto micropolar fluid past a stretched semi-infinite vertical and permeable surface taking into account heat absorption, hall and ion-slip effect, first-order chemical reaction, and radiation effects. The system of coupled nonlinear equations is solved numerically and the effects of various parameters on the velocity, the microrotation, the temperature, and the concentration field are calculated. The following discovery was made: an increase in the hall parameter strongly enhances the fluid velocity, an increase in the heat absorption parameter increases the temperature, and an increase in the slip parameter decreases the velocity. Additionally, the local skin friction, Nusselt number, and Sherwood number are also analyzed for various parameters and presented in table form.

  7. Decay heat and anti-neutrino energy spectra in fission fragments from total absorption spectroscopy

    Rykaczewski, Krzysztof

    2015-10-01

    Decay studies of over forty 238U fission products have been studied using ORNL's Modular Total Absorption Spectrometer. The results are showing increased decay heat values, by 10% to 50%, and the energy spectra of anti-neutrinos shifted towards lower energies. The latter effect is resulting in a reduced number of anti-neutrinos interacting with matter, often by tens of percent per fission product. The results for several studied nuclei will be presented and their impact on decay heat pattern in power reactors and reactor anti-neutrino physics will be discussed.

  8. Slip Effect on MHD Chemically Reacting Convictive Boundary Layer Flow with Heat Absorption

    Ayano, Mekonnen Shifferaw; Demeke, Negussie Tadege

    2016-01-01

    The aim of this paper is to investigate steady magneto micropolar fluid past a stretched semi-infinite vertical and permeable surface taking into account heat absorption, hall and ion-slip effect, first-order chemical reaction, and radiation effects. The system of coupled nonlinear equations is solved numerically and the effects of various parameters on the velocity, the microrotation, the temperature, and the concentration field are calculated. The following discovery was made: an increase i...

  9. Effects of heat stress on dynamic absorption process, tissue distribution and utilization efficiency of vitamin C in broilers

    The experiment was conducted to determine the effects of heat stress on ascorbic acid nutritional physiology of broilers with radioisotope technology. 3H-Vc was fed to broilers and then the blood, liver, kidney, breast muscle, and excreta were sampled to determine the dynamic absorption process, the tissue distribution and the utilization efficiency of vitamin C. The results indicated that the absorption, metabolism and mobilization of supplemented vitamin C in broilers with heat stress was faster than that in broilers without heat stress. However, the utilization efficiency of supplemented vitamin C in broilers with heat stress was not higher than that of broilers without heat stress

  10. A novel absorption refrigeration cycle for heat sources with large temperature change

    To increase the use efficiency of available thermal energy in the waste gas/water, a novel high-efficient absorption refrigeration cycle regarded as an improved single-effect/double-lift configuration is proposed. The improved cycle using an evaporator/absorber (E/A) promotes the coefficient of performance and reduces the irreversible loss. Water–lithium bromide is used as the working pair and a simulation study under the steady working conditions is conducted. The results show that the temperature of waste gas discharged is about 20 °C lower than that of the conventional single-effect cycle and the novel cycle we proposed can achieve more cooling capacity per unit mass of waste gas/water at the simulated working conditions. -- Graphical abstract: Pressure – temperature diagram for water – lithium bromide. Highlights: ► A novel waste heat-driven absorption refrigeration cycle is presented. ► The novel cycle can reject heat at much lower temperature. ► The available temperature range of heat source of the proposed cycle is wider. ► Multiple heat sources with different temperatures can be used in the novel cycle

  11. Energy simulation of solar assisted absorption system and examination of clearness index effects on auxiliary heating

    The smog and pollutants in the atmospheric air of heavily populated urban areas are anticipated to have substantial adverse effects on the collection of solar energy and the performance of solar energy systems. The objectives of this study are (a) to develop a simulation model for analyzing the performance of a water-LiBr solar assisted absorption system with an auxiliary heating source and (b) to examine the effects of clearness index on the auxiliary heating requirements. To achieve the objectives, a numerical model for a water-LiBr solar assisted absorption system is developed, and the influence of a reduction in the clearness index, based on actual recorded data, is investigated for constant and time varying cooling loads. Under the condition of peak solar gain on July 21, when a 1000 m2 solar collector is designed to provide 70% of the heating energy required for a constant cooling load of 1265 MJ/h (=100 refrigeration tons), as the system coefficient of performance decreases due to higher ambient temperatures, it is found that a reduction in the clearness index from 0.63 to 0.52 results in a 67% increase in auxiliary heating required of the boiler. It is concluded that accounting for clearness index data is necessary for accurate prediction of solar energy collection

  12. Resonant Absorption of Transverse Oscillations and Associated Heating in a Solar Prominence. I- Observational aspects

    Okamoto, Takenori J; De Pontieu, Bart; Uitenbroek, Han; Van Doorsselaere, Tom; Yokoyama, Takaaki

    2015-01-01

    Transverse magnetohydrodynamic (MHD) waves have been shown to be ubiquitous in the solar atmosphere and can in principle carry sufficient energy to generate and maintain the Sun's million-degree outer atmosphere or corona. However, direct evidence of the dissipation process of these waves and subsequent heating has not yet been directly observed. Here we report on high spatial, temporal, and spectral resolution observations of a solar prominence that show a compelling signature of so-called resonant absorption, a long hypothesized mechanism to efficiently convert and dissipate transverse wave energy into heat. Aside from coherence in the transverse direction, our observations show telltale phase differences around 180 degrees between transverse motions in the plane-of-sky and line-of-sight velocities of the oscillating fine structures or threads, and also suggest significant heating from chromospheric to higher temperatures. Comparison with advanced numerical simulations support a scenario in which transverse...

  13. MHD Free Convection from an Isothermal Truncated Cone with Variable Viscosity and Internal Heat Generation (Absorption

    A.H.Srinivasa,

    2016-02-01

    Full Text Available This paper presents a study of MHD free convection flow of an electrically conducting incompressible fluid with variable viscosity about an isothermal truncated cone in the presence of heat generation or absorption. The fluid viscosity is assumed to vary as a inverse linear function of temperature. The non-linear coupled partial differential equations governing the flow and heat transfer have been solved numerically by using an implicit finite - difference scheme along with quasilinearization technique. The non-similar solutions have been obtained for the problem, overcoming numerical difficulties near the leading edge and in the downstream regime. Results indicate that skin friction and heat transfer are strongly affected by, both, viscosity-variation parameter and magnetic field. In fact, the transverse magnetic field influences the momentum and thermal fields, considerably. Further, skin friction is found to decrease and heat transfer increases near the leading edge. Also, it is found that the direction of heat transfer gets reversed during heat generation.

  14. Demonstration project of a natural gas heated absorption heat pump for heating of buildings and service water; Demonstrationsprojekt einer mit Erdgas beheizten Absorptionswaermepumpe fuer Gebaeudeheizung und Brauchwasserbereitung

    Moser, Harald; Rieberer, Rene [Technische Univ. Graz (Austria). Inst. fuer Waermetechnik

    2011-07-01

    For IEA HPP Annex 34 ''Thermally Driven Heat Pumps for Heating and Cooling'', the Institut fuer Waermetechnik of TU Graz university carried out a demonstration project in which the seasonal performance factor of two ammonia/water absorption heat pumps for space and water heating was to be investigated. Each of the heat pumps had a rated capacity of 48 kW; they are used for heating a storage hall and offices and also service water for a brewery at Graz. The ground is used as heat source, and heat is distributed via a low-temperature floor heating system. The heat pumps have an integrated heat exchanger for flue gas condensation, in which part of the water vapour contained in the flue gas is condensed, and the condensation heat is recirculated into the heating unit. Measurements took place through 2010; all relevant temperatures and heating rates were measured as well as the natural gas volume flow and the electric power consumption. The system worked reliably and with high efficiency. A seasonal performance factor of 1.54 was achieved in 2010 as referred to the lower calorific value of the natural gas. The measurements also showed potential for improvement, especially in service water heating in the summer season. [German] Im Rahmen des IEA HPP Annex 34 ''Thermally Driven Heat Pumps for Heating and Cooling'' wurde am Institut fuer Waermetechnik der TU Graz ein Demonstrationsprojekt durchgefuehrt, mit dem Ziel die Jahresarbeitszahl von zwei Ammoniak/Wasser-Absorptionswaermepumpen (AWP) zur Gebaeudeheizung und Brauchwasserbereitung zu erheben. Die installierten AWP besitzen eine Nennleistung von je ca. 40 kW und stellen die benoetigte Heizwaerme fuer eine Lagerhalle und Bueroraeumlichkeiten sowie fuer das Brauchwasser eines Lagerzentrums einer Brauerei in Graz bereit. Als Waermequelle werden Erdreichsonden verwendet und zur Waermeverteilung ist ein Niedertemperatur-Fussbodenheizungssystem vorgesehen. Eine Besonderheit der

  15. Effect Of Operational Parameters On Heat and Mass Transfer In Generator of R134a/DMF Absorption Refrigeration System

    Annamalai, Mani; Pasupathy, Balamurugan

    2012-01-01

    Vapour absorption refrigeration systems (VARS) has regained the attention due to their potential for renewable/waste heat utilization. To improve the efficiency of these systems, it becomes obligatory to make component level studies on processes. In this present study, investigations on the heat and mass transfer in compact generator of the vapour absorption refrigeration system have been carried out using R134a-Dimethyl formamide (DMF). An experimental facility of VARS has been fabricated us...

  16. Effect of Internal Heat Recovery in Ammonia-Water Absorption Cooling Cycles: Exergy and Structural Analysis

    Miquel Nogués

    2009-03-01

    Full Text Available First and second law analysis have been conducted for three low temperature driven ammonia-water absorption cooling cycles with increasing internal heat recovery. Based on the results of exergy analysis the structural analysis has been achieved. The obtained Coefficients of Structural Bonds (CSB consider how the irreversibility of the whole cycle is affected by a change in the irreversibility related to an efficiency improvement of a single component. Trends for the different configurations are similar, while quantitative differences among the main heat exchangers are considerable. The highest values of the CSB are found for the refrigerant heat exchanger. Also the evaporator, the condenser, the generator and the absorber show values higher than unity. The lowest CSB’s are obtained in the solution heat exchanger. In general, CSB’s decrease with increasing efficiency. That means that for very efficient heat exchangers, a further improvement looks less attractive. The dephlegmator is an exception as it shows a singularity of the CSB value due to its complex interactions with the other components. Once the CSB’s are obtained for the main components, they can be used in the structural method of the thermoeconomic optimisation. This method enables us to find the optimum design of a component in a straightforward calculation.

  17. Gas turbine efficiency enhancement using waste heat powered absorption chillers in the oil and gas industry

    In hot climates, the efficiency of energy-intensive industrial facilities utilizing gas turbines for power generation, such as oil refineries and natural gas processing plants (NGPPs), can be enhanced by reducing gas turbine compressor inlet air temperature. This is typically achieved using either evaporative media coolers or electrically-driven mechanical vapor-compression chillers. However, the performance of evaporative media coolers is constrained in high relative humidity (RH) conditions, such as encountered in the Middle East and tropical regions, and such coolers require demineralized water supply, while electrically-driven mechanical vapor-compression chillers consume a significant amount of electric power. In this study, the use of gas turbine exhaust gas waste-heat powered, single-effect water–lithium bromide (H2O–LiBr) absorption chillers is thermo-economically evaluated for gas turbine compressor inlet air cooling scheme, with particular applicability to Middle East NGPPs. The thermodynamic performance of the proposed scheme, integrated in a NGPP, is compared with that of conventional evaporative coolers and mechanical vapor-compression chillers, in terms of key operating parameters, and either demineralized water or electricity consumption, respectively. The results show that in extreme ambient conditions representative of summer in the Persian Gulf (i.e., 55 °C, 80% RH), three steam-fired, single-effect H2O–LiBr absorption chillers utilizing 17 MW of gas turbine exhaust heat, could provide 12.3 MW of cooling to cool compressor inlet air to 10 °C. In the same ambient conditions, evaporative coolers would only provide 2.3 MW cooling capacity, and necessitate consumption of approximately 0.8 kg/s of demineralized water to be vaporized. In addition, mechanical vapor-compression chillers would require an additional 2.7 MW of electric energy to provide the same amount of cooling as H2O–LiBr absorption chillers. The additional electricity generated

  18. Performance of hybrid quad generation system consisting of solid oxide fuel cell system and absorption heat pump

    Cachorro, Irene Albacete; Daraban, Iulia Maria; Lainé, Guillaume; Singh, Navdeep; Liso, Vincenzo

    2013-01-01

    In this paper a system consisting of an SOFC system for cogeneration of heat and power and vapour absorption heat pump for cooling and freezing is assessed and performance is evaluated. Food industry where demand includes four forms of energy simultaneously is a relevant application such a system.The heat pump is a heat driven system and is running with the heat recovered by a heat exchanger from the exhausted gases from SOFC. The working fluid pair is NH3-H2O and is driven in two evaporators...

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

    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)

  20. Enhancement of LNG plant propane cycle through waste heat powered absorption cooling

    In liquefied natural gas (LNG) plants utilizing sea water for process cooling, both the efficiency and production capacity of the propane cycle decrease with increasing sea water temperature. To address this issue, several propane cycle enhancement approaches are investigated in this study, which require minimal modification of the existing plant configuration. These approaches rely on the use of gas turbine waste heat powered water/lithium bromide absorption cooling to either (i) subcool propane after the propane cycle condenser, or (ii) reduce propane cycle condensing pressure through pre-cooling of condenser cooling water. In the second approach, two alternative methods of pre-cooling condenser cooling water are considered, which consist of an open sea water loop, and a closed fresh water loop. In addition for all cases, three candidate absorption chiller configurations are evaluated, namely single-effect, double-effect, and cascaded double- and single-effect chillers. The thermodynamic performance of each propane cycle enhancement scheme, integrated in an actual LNG plant in the Persian Gulf, is evaluated using actual plant operating data. Subcooling propane after the propane cycle condenser is found to improve propane cycle total coefficient of performance (COPT) and cooling capacity by 13% and 23%, respectively. The necessary cooling load could be provided by either a single-effect, double-effect or cascaded and single- and double-effect absorption refrigeration cycle recovering waste heat from a single gas turbine operated at full load. Reducing propane condensing pressure using a closed fresh water condenser cooling loop is found result in propane cycle COPT and cooling capacity enhancements of 63% and 22%, respectively, but would require substantially higher capital investment than for propane subcooling, due to higher cooling load and thus higher waste heat requirements. Considering the present trend of short process enhancement payback periods in the

  1. Increasing utilisation of district heating through absorption cooling technology; Oekat fjaerrvaermeutnyttjande med hjaelp av absorptionstekniken

    Bjurstroem, Henrik; Ingvarsson, Paul; Zinko, Heimo

    2010-10-15

    The purpose of the research project presented in this report was to find ways to return a lower temperature from the generator of the chillers in a supply/return connection. The initial target is 40 deg C. Ideally, the absorption chiller and possible ulterior uses of the remaining heat in the heat carrier (the water flowing through the generator) should be as close as possible to a pure heat load. The hot-water driven absorption chillers used today to produce cooling in DH networks are exclusively so-called single-effect (Sweden) chillers with water and lithium bromide as working pair. This study aims at raising as much as possible the upper bounds on the absorption chiller capacity that may be connected to a DH network, by lowering the temperature at the outlet. To this end, several approaches have been used: - A search for alternative designs of the absorption chiller, focusing on commercially available and tested technology, both those yielding a large temperature decrease over the generator and those that may be operated at lower temperatures than the conventional solutions; - An examination of the impact of further uses of the remaining heat on temperature in the return line. larger. Smaller units are considered only if they can be used to illustrate a principle. As a complement to this investigation, a few other issues have been treated: - What temperature levels should a system actually be designed for? - The LAVA method to calculate the impact of supply and return temperatures in the DH network on the economics of power production is presented; - Interesting technical solutions using desiccant-aided evaporative cooling are shortly described; - The modern developments in the field of working pairs (refrigerant and absorbent) are reviewed. Assumptions made here are that there is a significant demand for cooling, and that the demand is large enough to justify operating the cogeneration plant at a load level exceeding its lowest acceptable part load rather than

  2. Resonant Absorption of Transverse Oscillations and Associated Heating in a Solar Prominence. II- Numerical aspects

    Antolin, Patrick; De Pontieu, Bart; Uitenbroek, Han; Van Doorsselaere, Tom; Yokoyama, Takaaki

    2015-01-01

    Transverse magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere and may be responsible for generating the Sun's million-degree outer atmosphere. However, direct evidence of the dissipation process and heating from these waves remains elusive. Through advanced numerical simulations combined with appropriate forward modeling of a prominence flux tube, we provide the observational signatures of transverse MHD waves in prominence plasmas. We show that these signatures are characterized by thread-like substructure, strong transverse dynamical coherence, an out-of-phase difference between plane-of-the-sky motions and LOS velocities, and enhanced line broadening and heating around most of the flux tube. A complex combination between resonant absorption and Kelvin-Helmholtz instabilities (KHI) takes place in which the KHI extracts the energy from the resonant layer and dissipates it through vortices and current sheets, which rapidly degenerate into turbulence. An inward enlargement of the boundary i...

  3. Validation of a PC based program for single stage absorption heat pump. Final report

    Zaltash, A.; Ally, M.R.

    1991-09-01

    An interactive computer code was developed to evaluate single stage absorption heat pump performance for temperature amplifier and heat amplifier modes using water as the refrigerant. This program performs the cycle calculations for single stage cycles based on the polynomial expressions developed to correlate experimental vapor-liquid-equilibrium (VLE) and specific enthalpy-concentration data for LiBr/water and (Li, K, Na)NO{sub 3}/water systems as well as the properties of pure water. The operating parameters obtained by this program were tested against mass and energy balances in documented cases and the results show that the maximum deviation between coefficient of performance (COP) values obtained by this software and the ones previously calculated is less than 3%. In addition, this program was used to study the effect of solution temperature leaving the absorber on the other operating parameters. This type of analysis could be used to improve and optimize cycle design. 4 refs.

  4. Validation of a PC based program for single stage absorption heat pump

    Zaltash, A.; Ally, M.R.

    1991-09-01

    An interactive computer code was developed to evaluate single stage absorption heat pump performance for temperature amplifier and heat amplifier modes using water as the refrigerant. This program performs the cycle calculations for single stage cycles based on the polynomial expressions developed to correlate experimental vapor-liquid-equilibrium (VLE) and specific enthalpy-concentration data for LiBr/water and (Li, K, Na)NO{sub 3}/water systems as well as the properties of pure water. The operating parameters obtained by this program were tested against mass and energy balances in documented cases and the results show that the maximum deviation between coefficient of performance (COP) values obtained by this software and the ones previously calculated is less than 3%. In addition, this program was used to study the effect of solution temperature leaving the absorber on the other operating parameters. This type of analysis could be used to improve and optimize cycle design. 4 refs.

  5. Resonance absorption, reflection, transmission of phonons and heat transfer through interface between two solids

    The different mechanisms of resonant transport of phonons between two media in the presence of an impurity intermediate layer are described. Particular attention is focused on the resonance interaction of elastic waves with a two-dimensional defect on the contact boundary between two solids, on the multichannel interface phonon scattering, and on the experimentally observed nonmonotonic temperature dependence of the reduced heat flux. In the cases when there is a direct interaction between edge atoms of the matrix as non-nearest neighbors or when the impurities do not fill completely the 2D interface layer, an additional channel for the transmission of phonons through the interface opens. This additional transmission channel manifests itself as a transmission (or reflection or absorption) peak with an asymmetric line shape (the so-called Fano-like resonance for phonons due to interference between the two transmission channels). Some applications of the Fano-like interference phenomena in magnon heat conductivity are also discussed

  6. First and second law multidimensional analysis of a triple absorption heat transformer (TAHT)

    Highlights: • A full factorial analysis is conducted upon a triple absorption heat transformer. • The most influential variable settings are determined. • Condensation temperature and pinch heat transfer gradient have the greatest influence. • Points of optimum exist for the temperatures of the two absorber evaporators. • The generator causes the most irreversibility. - Abstract: In this paper, a rigorous multi-dimensional analysis is conducted upon a triple absorption heat transformer (TAHT) using the working fluids water and lithium bromide (LiBr). A full factorial design is created which determines the most influential factors affecting the system’s coefficient of performance (COP), exergetic coefficient of performance (ECOP), flow ratio (FR) and total exergy destruction (ED). The aim is to draw general conclusions which may be adopted into any such TAHT cycle and not simply be specific to any one scenario. Accordingly the paper analyses the position of each variable across its thermodynamically available range instead of the traditional selection of arbitrary temperatures. It is found that in general the condensation temperature and the pinch heat transfer gradient selected have the greatest effect, and that these should be minimised in all situations. There exist points of optimum for the temperatures of the two absorber–evaporators within the cycle, however the evaporation temperature has conflicting effects for different dependent variables, and must therefore be selected based on an economic analysis. The results of this study also show that the generator is the source of the largest exergy destruction in the cycle, followed by the two absorber–evaporators

  7. On the coronal heating mechanism by the resonant absorption of Alfven waves

    H. Y. Alkahby

    1993-12-01

    Full Text Available In this paper, we will investigate the heating of the solar corona by the resonant absorption of Alfven waves in a viscous and isothermal atmosphere permeated by a horizontal magnetic field. It is shown that if the viscosity dominates the motion in a high (low- β plasma, it creates an absorbing and reflecting layer and the heating process is acoustic (magnetoacoustic. When the magnetic field dominates the oscillatory process it creates a non-absorbing reflecting layer. Consequently, the heating process is magnetohydrodynamic. An equation for resonance is derived. It shows that resonances may occur for many values of the frequency and of the magnetic field if the wavelength is matched with the strength of the magnetic field. At the resonance frequencies, magnetic and kinetic energies will increase to very large values which may account for the heating process. When the motion is dominated by the combined effects of the viscosity and the magnetic field, the nature of the reflecting layer and the magnitude of the reflection coefficient depend on the relative strengths of the magnetic field and the viscosity.

  8. Total Absorption Spectroscopy of Fission Fragments Relevant for Reactor Antineutrino Spectra and Decay Heat Calculations

    Porta A.

    2016-01-01

    Full Text Available Beta decay of fission products is at the origin of decay heat and antineutrino emission in nuclear reactors. Decay heat represents about 7% of the reactor power during operation and strongly impacts reactor safety. Reactor antineutrino detection is used in several fundamental neutrino physics experiments and it can also be used for reactor monitoring and non-proliferation purposes. 92,93Rb are two fission products of importance in reactor antineutrino spectra and decay heat, but their β-decay properties are not well known. New measurements of 92,93Rb β-decay properties have been performed at the IGISOL facility (Jyväskylä, Finland using Total Absorption Spectroscopy (TAS. TAS is complementary to techniques based on Germanium detectors. It implies the use of a calorimeter to measure the total gamma intensity de-exciting each level in the daughter nucleus providing a direct measurement of the beta feeding. In these proceedings we present preliminary results for 93Rb, our measured beta feedings for 92Rb and we show the impact of these results on reactor antineutrino spectra and decay heat calculations.

  9. Total Absorption Spectroscopy of Fission Fragments Relevant for Reactor Antineutrino Spectra and Decay Heat Calculations

    Porta, A.; Zakari-Issoufou, A.-A.; Fallot, M.; Algora, A.; Tain, J. L.; Valencia, E.; Rice, S.; Bui, V. M.; Cormon, S.; Estienne, M.; Agramunt, J.; Äystö, J.; Bowry, M.; Briz, J. A.; Caballero-Folch, R.; Cano-Ott, D.; Cucouanes, A.; Elomaa, V.-V.; Eronen, T.; Estévez, E.; Farrelly, G. F.; Garcia, A. R.; Gelletly, W.; Gomez-Hornillos, M. B.; Gorlychev, V.; Hakala, J.; Jokinen, A.; Jordan, M. D.; Kankainen, A.; Karvonen, P.; Kolhinen, V. S.; Kondev, F. G.; Martinez, T.; Mendoza, E.; Molina, F.; Moore, I.; Perez-Cerdán, A. B.; Podolyák, Zs.; Penttilä, H.; Regan, P. H.; Reponen, M.; Rissanen, J.; Rubio, B.; Shiba, T.; Sonzogni, A. A.; Weber, C.

    2016-03-01

    Beta decay of fission products is at the origin of decay heat and antineutrino emission in nuclear reactors. Decay heat represents about 7% of the reactor power during operation and strongly impacts reactor safety. Reactor antineutrino detection is used in several fundamental neutrino physics experiments and it can also be used for reactor monitoring and non-proliferation purposes. 92,93Rb are two fission products of importance in reactor antineutrino spectra and decay heat, but their β-decay properties are not well known. New measurements of 92,93Rb β-decay properties have been performed at the IGISOL facility (Jyväskylä, Finland) using Total Absorption Spectroscopy (TAS). TAS is complementary to techniques based on Germanium detectors. It implies the use of a calorimeter to measure the total gamma intensity de-exciting each level in the daughter nucleus providing a direct measurement of the beta feeding. In these proceedings we present preliminary results for 93Rb, our measured beta feedings for 92Rb and we show the impact of these results on reactor antineutrino spectra and decay heat calculations.

  10. Effect of thermal radiation and suction on convective heat transfer of nanofluid along a wedge in the presence of heat generation/absorption

    An analysis is presented to find the effects of thermal radiation and heat generation/absorption on convection heat transfer of nanofluid past a wedge in the presence of wall suction. The governing partial differential equations are transformed into a system of ordinary differential equations using similarity transformation. The resulting system is solved numerically using a fourth-order Runge–Kutta method with shooting technique. Numerical computations are carried out for different values of dimensionless parameters to predict the effects of wedge angle, thermophoresis, Brownian motion, heat generation/absorption, thermal radiation and suction. It is found that the temperature increases significantly when the value of the heat generation/absorption parameter increases. But the opposite observation is found for the effect of thermal radiation

  11. Effect of thermal radiation and suction on convective heat transfer of nanofluid along a wedge in the presence of heat generation/absorption

    Kasmani, Ruhaila Md; Bhuvaneswari, M. [Centre for Foundation Studies in Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Sivasankaran, S.; Siri, Zailan [Institute of Mathematical Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-10-22

    An analysis is presented to find the effects of thermal radiation and heat generation/absorption on convection heat transfer of nanofluid past a wedge in the presence of wall suction. The governing partial differential equations are transformed into a system of ordinary differential equations using similarity transformation. The resulting system is solved numerically using a fourth-order Runge–Kutta method with shooting technique. Numerical computations are carried out for different values of dimensionless parameters to predict the effects of wedge angle, thermophoresis, Brownian motion, heat generation/absorption, thermal radiation and suction. It is found that the temperature increases significantly when the value of the heat generation/absorption parameter increases. But the opposite observation is found for the effect of thermal radiation.

  12. Natural Convection Heat and Mass Transfer Flow with Hall Current, Rotation, Radiation and Heat Absorption Past an Accelerated Moving Vertical Plate with Ramped Temperature

    Gauri Shanker Seth

    2015-01-01

    Full Text Available An investigation of unsteady hydromagnetic natural convection heat and mass trans fer flow with Hall current of a viscous, incompressible, electrically conducting, heat absorbing and optically thin radiating fluid past an accelerated moving vertical plate through fluid saturated porous medium in a rotating environment is carried out when temperature of the plate has a temporarily ramped profile. The exact solutions of momentum, energy and concentration equations are obtained in closed form by Laplace transform technique. The expressions of skin friction, Nusselt number and Sherwood number are also derived. For both ramped temperature and isothermal plates, Hall current tends to accelerate primary and secondary fluid velocities whereas heat absorption and radiation have reverse effect on it. Rotation tends to retard primary fluid velocity whereas it has a reverse effect on secondary fluid velocity. Heat absorption and radiation have tendency to enhance rate of heat transfer at the plate.

  13. Thermodynamic optimization of a solar system for cogeneration of water heating/purification and absorption cooling

    Hovsapian, Zohrob O.

    This dissertation presents a contribution to understanding the behavior of solar powered air conditioning and refrigeration systems with a view to determining the manner in which refrigeration rate; mass flows, heat transfer areas, and internal architecture are related. A cogeneration system consisting of a solar concentrator, a cavity-type receiver, a gas burner, and a thermal storage reservoir is devised to simultaneously produce water heating/purification and cooling (absorption refrigerator system). A simplified mathematical model, which combines fundamental and empirical correlations, and principles of classical thermodynamics, mass and heat transfer, is developed. An experimental setup was built to adjust and validate the numerical results obtained with the mathematical model. The proposed model is then utilized to simulate numerically the system transient and steady state response under different operating and design conditions. A system global optimization for maximum performance (or minimum exergy destruction) in the search for minimum pull-down and pull-up times, and maximum system second law efficiency is performed with low computational time. Appropriate dimensionless groups are identified and the results presented in normalized charts for general application. The numerical results show that the three way maximized system second law efficiency, etaII,max,max,max, occurs when three system characteristic mass flow rates are optimally selected in general terms as dimensionless heat capacity rates, i.e., (Psisps , Psiwxwx, PsiHs)opt ≅ (1.43, 0.17, 0.19). The minimum pull-down and pull-up times, and maximum second law efficiencies found with respect to the optimized operating parameters are sharp and, therefore important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar energy systems in the context of distributed power generation.

  14. Kinetic effects in Alfven wave heating Part 2 propagation and absorption with a single minority species

    Kinetic effects of Alfven wave spatial resonances near the plasma edge are investigated numerically and analytically in a cylindrical tokamak model. In Part 1, cold plasma surface Alfven eigenmodes (SAE's) in a pure plasma are examined. Numerical calculations of antenna-driven waves exhibiting absorption resonances at certain discrete frequencies are first reviewed. From a simplified kinetic equation, an analytical dispersion relation is then obtained with the antenna current set equal to zero. The real and imaginary parts of its roots, which are the complex eigenfrequencies, agree with the central frequencies and widths, respectively, of the numerical antenna-driven resonances. These results serve as an introduction to the companion paper, in which it is shown that, in the presence of a minority species, certain SAE's, instead of heating the plasma exterior, can dissipate substantial energy in the two-ion hybrid layer near the plasma center. 11 refs., 8 figs., 1 tab

  15. Absorption refrigeration using waste heat; Refrigeracion por absorcion utilizando calor de desecho

    Heard, Christopher; Ayala, Ramon; Best, Roberto [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1994-07-01

    In this article a detailed analysis is made of the absorption refrigeration system that uses waste heat and because of being of low temperature, can make the processes more efficient being at the same time an important factor in the country`s energy resources saving, since the system permits to increase the availability of electricity and fuel`s energy. The Instituto de Investigaciones Electricas (IIE) and the Universidad Nacional Autonoma de Mexico (UNAM) absorption refrigeration experience is described and the economic aspects related with this system are analyzed. [Espanol] En este articulo se presenta un analisis detallado del sistema de refrigeracion por absorcion que utiliza calor de desecho y que, siendo de baja temperatura, puede hacer mas eficientes los procesos y ser a la vez un factor importante en el ahorro de los recursos energeticos del pais, pues el sistema permite aumentar la disponibilidad energetica de electricidad y combustibles. Se describe la experiencia del Instituto de Investigaciones Electricas (IIE) en refrigeracion por absorcion y la de la Universidad Nacional Autonoma de Mexico (UNAM), y se analizan los aspectos economicos relacionados con este sistema.

  16. Performance analysis of ejector absorption heat pump using ozone safe fluid couple through artificial neural networks

    Thermodynamic analysis of absorption thermal systems is too complex because the analytic functions calculating the thermodynamic properties of fluid couples involve the solution of complex differential equations and simulation programs. This study aims at easing this complex situation and consists of three cases: (i) A special ejector, located at the absorber inlet, instead of the common location at the condenser inlet, to increase overall performance was used in the ejector absorption heat pump (EAHP). The ejector has two functions: Firstly, it aids the pressure recovery from the evaporator and then upgrades the mixing process and pre-absorption by the weak solution of the methanol coming from the evaporator. (ii) Use of artificial neural networks (ANNs) has been proposed to determine the properties of the liquid and two phase boiling and condensing of an alternative working fluid couple (methanol/LiCl), which does not cause ozone depletion. (iii) A comparative performance study of the EAHP was performed between the analytic functions and the values predicted by the ANN for the properties of the couple. The back propagation learning algorithm with three different variants and logistic sigmoid transfer function were used in the network. In order to train the neural network, limited experimental measurements were used as training and test data. In the input layer, there are temperature, pressure and concentration of the couples. Specific volume is in the output layer. After training, it was found that the maximum error was less than 3%, the average error was less than 1.2% and the R2 values were about 0.9999. Additionally, in comparison of the analysis results between analytic equations obtained by using experimental data and by means of the ANN, the deviations of the refrigeration effectiveness of the system for cooling (COPr), exergetic coefficient of performance of the system for cooling (ECOPr) and circulation ratio (F) for all working temperatures were found to

  17. Improvement of the performance of an absorption heat transformer through a single effect process to obtain freshwater

    The thermodynamic cycles have a huge potential to increase the usage of energetic efficiency. A lot works about the Absorption Heat Transformers have been studied worldwide, since these can be coupled at different processes with residual and/or renewable energies from 60 to 80 °C. This paper shows new Configurations for an Absorption Heat Transformer and a water distillation system in order to increase its performance. The evaporation process used is a single effect for seawater. The sensible heat preheats the working solution from the generator, refrigerant from the evaporator or condenser, while the latent heat is used to preheat the seawater inlet. The theoretical analysis is done with a thermodynamic model, which was validated with data reported in the literature. Different scenarios have been analyzed in order to determinate the best optimal configuration under several operating parameters. Based on the results, the best behavior is searched when the sensible heat is applied between the condenser and the evaporator, since it is possible to increase the thermal performance up to 7.95% with respect to basic AHT and 16.38% when the AHT uses a SHX. The Specific Recuperation Heat and the Specific Useful Heat are recommended to know how much heat can be recovered per each 1 kg/s of distilled water. - Highlights: • Three new configurations for an Absorption Heat Transformer are proposed. • The COP increases 16.38% by using sensible and latent heat from the distillation process. • It is possible to recycle almost up to 76% from absorber heat for energy saving

  18. Annual performance investigation and economic analysis of heating systems with a compression-assisted air source absorption heat pump

    Highlights: • Optimal compression ratio of CASAHP is obtained for the maximum energy saving rate. • Annual performance is improved by 10–20% compared to ASAHP without compression. • Energy saving rate is 17.7–29.2% and investment is reduced to 30–60% for CASAHP. • Both compression and partial-design enhance the economy with given energy saving. • Payback time is reduced from 12–32 to 3–6 years by compression and partial-design. - Abstract: The compression-assisted air source absorption heat pump (CASAHP) is a promising alternative heating system in severe operating conditions. In this research, parameter studies on the annual performance under various compression ratios (CRs) and source temperatures are performed to achieve the maximum energy saving rates (ESRs). Economic analyses of the CASAHP under different CRs and partial-design ratios are conducted to obtain an optimal design that considers both energy savings and economy improvements. The results show that the optimal CR becomes higher in colder regions and with lower heat source temperatures. For a source temperature of 130 °C, the optimal CR values in all of the cities are within 2.0. For source temperatures from 100 to 130 °C, the maximum ESR is in the range of 17.7–29.2% in the studied cities. The efficiency improvement rate (EIR) caused by compression in a severe source condition can reach 10.0–20.0%. From the viewpoint of economy, the relative investment of CASAHP is reduced to 30–60% with a CR of 2.0–3.0. With a 2–6% sacrifice in ESR, the payback period can be reduced from 12–32 to 5–9 years using compression. Partial-design of the CASAHP can further reduce the payback period to 3–6 years with a partial-design ratio of 50% and a CR of 2.8. Additionally, CRs and partial-design ratios are designed comprehensively by seeking the maximum ESR for a given acceptable payback period

  19. Effects of Slip and Heat Generation/Absorption on MHD Mixed Convection Flow of a Micropolar Fluid over a Heated Stretching Surface

    Shimaa Waheed; Mostafa Mahmoud

    2010-01-01

    A theoretical analysis is performed to study the flow and heat transfer characteristics of magnetohydrodynamic mixed convection flow of a micropolar fluid past a stretching surface with slip velocity at the surface and heat generation (absorption). The transformed equations solved numerically using the Chebyshev spectral method. Numerical results for the velocity, the angular velocity, and the temperature for various values of different parameters are illustrated graphically. Also, the effect...

  20. Integrated energy, economic, and environmental assessment for the optimal solar absorption cooling and heating system

    Hang, Yin

    Buildings in the United States are responsible for 41% of the primary energy use and 30% of carbon dioxide emissions. Due to mounting concerns about climate change and resource depletion, meeting building heating and cooling demand with renewable energy has attracted increasing attention in the energy system design of green buildings. One of these approaches, the solar absorption cooling and heating (SACH) technology can be a key solution to addressing the energy and environmental challenges. SACH system is an integration of solar thermal heating system and solar thermal driven absorption cooling system. So far, SACH systems still remain at the demonstration and testing stage due to not only its high cost but also complicated system characteristics. This research aims to develop a methodology to evaluate the life cycle energy, economic and environmental performance of SACH systems by high-fidelity simulations validated by experimental data. The developed methodology can be used to assist the system design. In order to achieve this goal, the study includes four objectives as follows: * Objective 1: Develop the evaluation model for the SACH system. The model includes three aspects: energy, economy, and environment from a life cycle point of view. * Objective 2: Validate the energy system model by solar experiments performance data. * Objective 3: Develop a fast and effective multi-objective optimization methodology to find the optimal system configuration which achieves the maximum system benefits on energy, economy and environment. Statistic techniques are explored to reveal the relations between the system key parameters and the three evaluation targets. The Pareto front is generated by solving this multi-objective optimization problem. * Objective 4: Apply the developed assessment methodology to different building types and locations. Furthermore, this study considered the influence of the input uncertainties on the overall system performance. The sensitivity

  1. Effects of heat treatment on dynamic compressive properties and energy absorption characteristics of open-cell aluminum alloy foams

    2006-01-01

    The effects of heat treatment on the dynamic compressive properties and energy absorption characteristics of open cell aluminum alloy foams (Al-Mg-Si alloy foam and Al-Cu-Mg alloy foam) produced by infiltrating process were studied. Two kinds of heat treatment were exploited: age-hardening and solution heat treating plus age-hardening (T6). The split Hopkinson pressure bar (SHPB)was used for high strain rate compression test. The results show that both age-hardened and T6-strengthened foams exhibit improved compression strength and shortened plateau region compared with tnat of foams in as-fabricated state under high strain rate compression,and the energy absorption capacity is also influenced significantly by heat treatment. It is worthy to note that omitting the solution treating can also improve the strength and energy absorbed much.

  2. Heating from free-free absorption and the mass-loss rate of the progenitor stars to supernovae

    An accurate determination of the mass-loss rate of the progenitor stars to core-collapse supernovae is often limited by uncertainties pertaining to various model assumptions. It is shown that under conditions when the temperature of the circumstellar medium is set by heating due to free-free absorption, observations of the accompanying free-free optical depth allow a direct determination of the mass-loss rate from observed quantities in a rather model-independent way. The temperature is determined self-consistently, which results in a characteristic time dependence of the free-free optical depth. This can be used to distinguish free-free heating from other heating mechanisms. Since the importance of free-free heating is quite model dependent, this also makes possible several consistency checks of the deduced mass-loss rate. It is argued that the free-free absorption observed in SN 1993J is consistent with heating from free-free absorption. The deduced mass-loss rate of the progenitor star is, approximately, 10–5 M ☉ yr–1 for a wind velocity of 10 km s–1.

  3. Theoretical comparison of single-stage and advanced absorption heat transformers used to increase solar pond's temperature

    Rivera, W; Best, Roberto [Centro de Investigacion en Energia-UNAM, Temixco, Morelos (Mexico)

    2000-07-01

    Mathematical models of single-stage and advanced absorption heat transformers operating with the water/Carrol{sup T}M mixture were developed to simulate the performance of these systems coupled to a solar pond in order to increase the temperature of the useful heat produced by solar ponds. The results showed that the single-stage and the double absorption heat transformer are the most promising configuration to be coupled to solar ponds. With single-stage heat transformers it is possible to increase solar pond's temperature until 50 Celsius degrees with coefficients of performance of about 0.48 and with double absorption heat transformers until 100 Celsius degrees with coefficients of performance of 0.33. [Spanish] Se desarrollaron modelos matematicos de una sola etapa y transformadores avanzados de absorcion de calor operando con la mezcla agua/Carrol{sup T}M para simular el rendimiento de estos sistemas acoplados a un estanque solar con el objeto de aumentar la temperatura del calor util producido por los estanques solares. Los resultados mostraron que la etapa sencilla y el transformador de calor de absorcion doble son la configuracion mas prometedora para ser acoplado a estanques solares. Con los transformadores de calor de una sola etapa es posible aumentar la temperatura del estanque solar hasta 50 grados Celsius con coeficientes de rendimiento de alrededor de 0.48 y con transformadores de calor de doble absorcion hasta 100 grados Celsius con coeficientes de rendimiento de 0.33.

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

    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.

  5. Evaluation of electrochemical generation of volatile zinc hydride by heated quartz tube atomizer atomic absorption spectrometry.

    Arbab-Zavar, Mohammad-Hossein; Chamsaz, Mahmoud; Youssefi, Abbas; Aliakbari, Mostafa

    2012-01-01

    Electrochemical hydride generation (EcHG) as a sample introduction system for determination of zinc was developed. It was directly coupled to an electrically heated quartz tube atomizer (QTA) atomic absorption spectrometry (AAS) system. The hydride generator is a laboratory-made semi-batch electrolytic cell that consists of a lead-tin alloy cathode and a platinum anode. The effects of typical parameters on the generation efficiency of the technique, such as types of cathode material and catholyte and anolyte solutions, were studied. The influences of numerical experimental operating parameters on the analytical signal were evaluated in detail and optimum conditions were obtained. The analytical figures of merit for the developed method were determined. The calibration curve was linear up to 300 ng mL(-1) of Zn. A concentration detection limit (3σ, n = 9) of 11 ng mL(-1) Zn and a relative standard deviation of 5.0% (RSD, n = 9) for 200 ng mL(-1) Zn were accessed. In addition, the susceptibility of interference from various ions was evaluated. The accuracy of the method was verified by determination of Zn in a certified reference material and in tap water. The achieved concentrations were found to be in good agreement with both the certified value and the data obtained using flame AAS. PMID:22790376

  6. Experimental study of an ammonia-water bubble absorber using a plate heat exchanger for absorption refrigeration machines

    The development of absorption chillers activated by renewable heat sources has increased due mainly to the increase in primary energy consumption that causes problems such as greenhouse gases and air pollution among others. These machines, which could be a good substitute for compression systems, could be used in the residential and food sectors which require a great variety of refrigeration conditions. Nevertheless, the low efficiency of these machines makes it necessary to enhance heat and mass transfer processes in the critical components, mainly the absorber, in order to reduce their large size. This study used ammonia-water as the working fluid to look at how absorption takes place in a plate heat exchanger operating under typical conditions of absorption chillers, driven by low temperature heat sources. Experiments were carried out using a corrugated plate heat exchanger model NB51, with three channels, where ammonia vapor was injected in bubble mode into the solution in the central channel. The results achieved for the absorption flux were in the range of 0.0025-0.0063 kg m-2 s-1, the solution heat transfer coefficient varied between 2.7 and 5.4 kW m-2 K-1, the absorber thermal load from 0.5 to 1.3 kW. In addition, the effect of the absorber operating conditions on the most significant efficiency parameters was analyzed. The increase in pressure, solution and cooling flow rates positively affect the absorber performance, on the other hand an increase in the concentration, cooling, and solution temperature negatively affects the absorber performance

  7. Performance Evaluation of a Lithium-Chloride Absorption Refrigeration and an Assessment of Its Suitability for Biomass Waste Heat

    Sacha Oberweis

    2012-10-01

    Full Text Available This paper presents a computer model that will evaluate the performance of a thermo-chemical accumulator. The model is based on operational data such as temperatures and flow rates. The ultimate goal for this model is to estimate the coefficient of performance (COP of this unit when run on hot water from biomass combustion as the heat source. The outputs of the model are verified by comparing the simulation of the actual machine with published experimental data. The computed results for cooling COP are within 10% of the measured data. The simulations are all run for heat load temperatures varying between 80 °C and 110 °C. As expected, simulation results showed an increase in COP with increased heat source temperatures. The results demonstrate that the potential of combined solar and biomass combustion as a heat source for absorption cooling/heating in climates with low solar radiation can be coupled with biomass waste.

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

    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

  9. Effect of Chemical Reaction on Convective Heat Transfer of Boundary Layer Flow in Nanofluid over a Wedge with Heat Generation/Absorption and Suction

    R. M. Kasmani

    2016-01-01

    Full Text Available The aim of the present study is to examine the convective heat transfer of nanofluid past a wedge subject to first-order chemical reaction, heat generation/absorption and suction effects. The influence of wedge angle parameter, thermophoresis, Dufour and Soret type diffusivity are included. The local similarity transformation is applied to convert the governing nonlinear partial differential equations into ordinary differential equations. Shooting method integrated with fourth-order Runge-Kutta method is used to solve the ordinary differential equations. The skin friction, heat and mass transfer rates as well as the effects of various parameters on velocity, temperature and solutal concentration profiles are analyzed. The results indicate that when the chemical reaction parameter increases, the heat transfer coefficient increases while the mass transfer coefficient decreases. The effect of chemical reaction parameter is very important in solutal concentration field compared to velocity and temperature profiles since it decreases the solutal concentration of the nanoparticle.

  10. Numerical solution of Williamson fluid flow past a stretching cylinder and heat transfer with variable thermal conductivity and heat generation/absorption

    M. Y. Malik

    2016-03-01

    Full Text Available In this article, Williamson fluid flow and heat transfer over a stretching cylinder is discussed. The thermal conductivity is assumed to be vary linearly with temperature. Heat generation/absorption effects are also taken into account. Modeled partial differential equations are converted into ordinary differential form by using appropriate transformations. Shooting method in conjunction with Runge-Kutta-Fehlberg method is used to find the solution of the problem. Moreover, the effects of different flow parameters γ, λ, ϵ, β and Pr on velocity and temperature profiles are shown graphically. Local Nusselt number and skin friction coefficient are shown in tabular and graphical form.

  11. Simple analysis of total mercury and methylmercury in seafood using heating vaporization atomic absorption spectrometry.

    Yoshimoto, Keisuke; Anh, Hoang Thi Van; Yamamoto, Atsushi; Koriyama, Chihaya; Ishibashi, Yasuhiro; Tabata, Masaaki; Nakano, Atsuhiro; Yamamoto, Megumi

    2016-01-01

    This study aimed to develop a simpler method for determining total mercury (T-Hg) and methylmercury (MeHg) in biological samples by using methyl isobutyl ketone (MIBK) in the degreasing step. The fat in the samples was extracted by MIBK to the upper phase. T-Hg transferred into the water phase. This was followed by the extraction of MeHg from the water phase using HBr, CuCl2 and toluene. The MeHg fraction was reverse-extracted into L-cysteine-sodium acetate solution from toluene. The concentrations of T-Hg and MeHg were determined by heating vaporization atomic absorption spectrometry. Certified reference materials for T-Hg and MeHg in hair and fish were accurately measured using this method. This method was then applied to determine T-Hg and MeHg concentrations in the muscle, liver and gonads of seafood for the risk assessment of MeHg exposure. The mean T-Hg and MeHg concentrations in squid eggs were 0.023 and 0.022 µg/g, and in squid nidamental glands 0.052 and 0.049 µg/g, respectively. The MeHg/T-Hg ratios in the eggs and nidamental glands of squid were 94.4% and 96.5%, respectively. The mean T-Hg and MeHg concentrations in the gonads of sea urchins were 0.043 and 0.001 µg/g, respectively, with a MeHg/T-Hg ratio of 3.5%. We developed an efficient analytical method for T-Hg and MeHg using MIBK in the degreasing step. The new information on MeHg concentration and MeHg/T-Hg ratios in the egg or nidamental glands of squid and gonads of sea urchin will also be useful for risk assessment of mercury in seafood. PMID:27432235

  12. Effects of heat treatment on optical absorption properties of Ni-P/AAO nano-array composite structure

    Liu, Yi-Fan; Wang, Feng-Hua; Guo, Dong-Lai; Huang, Sheng-You; Zou, Xian-Wu [Wuhan University, Department of Physics, Wuhan (China); Sang, Jian-Ping [Wuhan University, Department of Physics, Wuhan (China); Jianghan University, Department of Physics, Wuhan (China)

    2009-11-15

    Ni-P/AAO nano-array composite structure assemblies with Ni and P grown in the pores of anodic aluminum oxide (AAO) membranes were prepared by electroless deposition. The results of SEM, TEM and SAED show that as-deposited Ni-P nanowires have an amorphous structure and a few nanocrystallites form after annealing. The optical absorption spectra reveal that, as the annealing temperature increases, the absorption band edge of the Ni-P/AAO composite structure is obviously blue shifted, which is attributed to a decrease of the internal pressure after heat treatment. Meanwhile, the annealed Ni-P/AAO nano-array composite structure exhibits the absorption behavior of a direct band gap semiconductor. Details of this behavior are discussed together with the implications for potential device applications. (orig.)

  13. An experimental integrated absorption heat pump effluent purification system. Pt. 1: Operating on water/lithium bromide solutions

    Santoyo-Gutierrez, S.; Santoyo, E. [Unidad Geotermia (Mexico); Siqueiros, J. [Unidad Energias No-Convencionales (Mexico); Heard, C.L. [Unidad Uso de la Energia Electrica, Inst. de Investigaciones Electricas, Temixco (Mexico); Holland, F.A. [Salford Univ., Overseas Educational Development Office, Salford (United Kingdom)

    1999-05-01

    The merits of single stage absorption heat pumps coupled to simple distillation for effluent treatment are discussed. An experimental integrated absorption heat pump effluent purification system (IAHPEPS) was built and operated with water-lithium bromide as a working mixture. This unit has been used to raise the temperature and hence, the vapour pressure of the impure water contained in one vessel, to the point where pure water vapour will distil from impure effluent solution (tap water or brine) and condense in a second vessel used to collect pure water. Pure effluent production rates of between 0.5 and 4.3 kg h{sup -1} were obtained. The actual coefficient of performance (COP{sub A}) and the heat pump effectiveness varied from 1.1 to 1.4 and 0.58 to 0.72, respectively. The results from the small scale systems indicate the likely results from industrial scale units which could be operated with low quality heat such as waste heat, solar or geothermal resources. (Author)

  14. Use of process steam in vapor absorption refrigeration system for cooling and heating applications: An exergy analysis

    S. Anand

    2016-12-01

    Full Text Available The exponential increase in cost of conventional fuels shifts the interest toward the use of alternative as well waste energy sources for the operation of refrigeration and air-conditioning units. The present study therefore analyzes the performance of a process steam-operated vapor absorption system for cooling and heating applications using ammonia and water as working fluids based on first and second laws of thermodynamics. A mathematical model has been developed based on exergy analysis to investigate the performance of the system. The different performance parameters such as coefficient of performance (COP and exergetic efficiency of absorption system for cooling and heating applications are also calculated under different operating conditions. The results obtained show that cooling and heating COP along with second law efficiency (exergy efficiency increases with the heat source temperature at constant evaporator, condenser, and absorber temperature. Also, COP as well as exergy efficiency increases with an increase in the evaporator temperature at constant generator, condenser, and absorber temperature. The effect of ambient temperature on the exergetic efficiency for cooling and heating applications is also studied. The results obtained from the simulation studies can be used to optimize different components of the system so that the performance can be improved significantly.

  15. Thermal modeling of a novel thermosyphonic waste heat absorption system for internal combustion engines

    This paper investigates a thermal system that absorbs waste heat from an internal combustion (IC) engine in order to raise the temperature of a working fluid to a saturated state using thermosyphonic flow, non-intrusive of the engine operations. The absorbed heat is rejected to an enclosed space, suitable for in-transit drying. The thermal system comprises a cross-flow heat exchanger connected to a radiator which preheats the working fluid from an insulated (storage) tank. The preheated fluid flows through a radiant heat absorber which absorbs radiant heat from the exhaust manifold. To ensure that the system efficiently performs, a temperature differential is maintained by the heated space while the fluid is cyclically delivered to the tank. The system’s operations are described using a novel flow cycle, and the results indicate a significant heat recovery potential. - Highlights: • This paper investigates a thermal system that absorbs waste heat from an internal combustion (IC) engine. • The absorbed heat is used to raise the temperature of a working fluid employing thermosyphonic flow. • The preheated fluid flows through a radiant heat absorber which absorbs radiant heat from the exhaust manifold. • To ensure that the system efficiently performs, a temperature differential is maintained by a heated space. • The system's operations are described using a novel flow cycle

  16. Seven-effect absorption refrigeration

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  17. Hydromagnetic Mixed Convective Nanofluid Slip Flow past an Inclined Stretching Plate in the Presence of Internal Heat Absorption and Suction

    S. P. Anjali Devi

    2016-01-01

    Full Text Available The steady two-dimensional mixed convective boundary layer flow of nanofluid over an inclined stretching plate with the effects of magnetic field, slip boundary conditions, suction and internal heat absorption have been investigated numerically. Two different types of nanoparticles, namely copper and alumina with water as the base fluid are considered. Similarity transformations are employed to transform the governing nonlinear partial differential equations into coupled non-linear ordinary differential equations. The influence of pertinent parameters such as magnetic interaction parameter, angle of inclination, volume fraction, suction parameter, velocity slip parameter, thermal jump parameter, heat absorption parameter, mixed convection parameter and Prandtl number on the flow and heat transfer characteristics are discussed. A representative set of results are displayed graphically to illustrate the issue of governing parameters on the dimensionless velocity and temperature. Numerical values of skin friction coefficient and the Nusselt number are shown in tabular form. A comparative study between the previously published work and the present results in a limiting sense reveals excellent agreement between them.

  18. Heat of Absorption of CO2 in Phase Change Solvents: 2-(Diethylamino)ethanol and 3-(Methylamino)propylamine

    Waseem Arshad, Muhammad; Fosbøl, Philip Loldrup; von Solms, Nicolas;

    2013-01-01

    Heat of absorption of CO2 in phase change solvents containing 2-(diethylamino)ethanol (DEEA) and 3-(methylamino)propylamine (MAPA) were measured as a function of CO2 loading at different temperatures using a commercially available reaction calorimeter. The tested systems were aqueous single amines...... (5 M DEEA, 2 M MAPA, and 1 M MAPA) and aqueous amine mixtures (5 M DEEA + 2 M MAPA and 5 M DEEA + 1 M MAPA) which give two liquid phases on reacting with CO2. All parallel experiments have shown good repeatability. The measurements were taken isothermally at three different temperatures, (40, 80, and...... to these two parameters, it also depends on temperature and the type of amine used. Tertiary alkanolamine (DEEA) has shown greater dependency on these parameters compared to the diamine (MAPA) containing both primary and secondary amine functional groups. In aqueous amine mixtures, heats of...

  19. Unsteady MHD convection and mass transfer flow of micropolar fluids past a vertical permeable moving plate with heat absorption

    By the use of the theory of micropolar fluids due to Eringen, perturbation method is presented to study an unsteady MHD convection and mass transfer flow of micropolar fluids past a vertical permeable moving plate with heat absorption. The plate moves with a constant velocity in the direction of fluid flow, while the free stream velocity follows an exponentially increasing or decreasing small perturbation law. Approximate solutions of the coupled nonlinear governing equations are obtained for different values of microrotation and magnetic parameters. Numerical calculations are carried out for the various parameters entering into the problem. The results of velocity, angular velocity, temperature and concentration profiles have been presented graphically for various values of the material parameters. The results indicate that the micropolar fluids display a reduction in drag as well as heat transfer rate when compared with Newtonian fluids. (author)

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

    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)

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

    The influence of the pressure drop in Plate Heat Exchangers (PHE) in the boiling temperature of LiBr-H2O and NH3-H2O solutions is studied. For the NH3-H2O 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-H2O 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.

  2. Energetic and exergetic performance analyses of a combined heat and power plant with absorption inlet cooling and evaporative aftercooling

    In this paper, exergy method is applied to analyze the gas turbine cycle cogeneration with inlet air cooling and evaporative aftercooling of the compressor discharge. The exergy destruction rate in each component of cogeneration is evaluated in detail. The effects of some main parameters on the exergy destruction and exergy efficiency of the cycle are investigated. The most significant exergy destruction rates in the cycle are in combustion chamber, heat recovery steam generator and regenerative heat exchanger. The overall pressure ratio and turbine inlet temperature have significant effect on exergy destruction in most of the components of cogeneration. The results obtained from the analysis show that inlet air cooling along with evaporative aftercooling has an obvious increase in the energy and exergy efficiency compared to the basic gas turbine cycle cogeneration. It is further shown that the first-law efficiency, power to heat ratio and exergy efficiency of the cogeneration cycle significantly vary with the change in overall pressure ratio and turbine inlet temperature but the change in process heat pressure shows small variation in these parameters. -- Highlights: → Application of exergy analysis along with energy analysis of gas turbine cogeneration is essential in order to observe its complete thermodynamic view. → We adopt absorption inlet cooling along with evaporative aftercooling in gas turbine cogeneration which results in significant performance improvement. → Analysis of the results concluded that the major option to improve the global thermal efficiency of gas turbine cogeneration is to reduce the local irreversibility rates in the combustion chamber. → Evaporative aftercooling along with absorption inlet cooling results in higher optimum pressure ratios. → It is recognized that experimental studies are needed to establish the practical usefulness of this proposed cycle.

  3. A Cooling System for an Automobile Based on Vapour Absorption Refrigeration Cycle Using Waste Heat of an Engine.

    Satish K. Maurya

    2014-03-01

    Full Text Available Now a days the air conditioning system of cars is mainly uses “Vapour Compression Refrigerant System” (VCRS which absorbs and removes heat from the interior of the car that is the space to be cooled and rejects the heat to atmosphere. In vapour compression refrigerant system, the system utilizes power from engine shaft as the input power to drive the compressor of the refrigeration system, hence the engine has to produce extra work to run the compressor of the refrigerating system utilizing extra amount of fuel. This loss of power of the vehicle for refrigeration can be neglected by utilizing another refrigeration system i.e. a “Vapour Absorption Refrigerant System”. As well known thing about VAS that these machines required low grade energy for operation. Hence in such types of system, a physicochemical process replaces the mechanical process of the Vapour Compression Refrigerant System by using energy in the form of heat rather than mechanical work. This heat obtained from the exhaust of high power internal combustion engines.

  4. Space Launch System Base Heating Test: Tunable Diode Laser Absorption Spectroscopy

    Parker, Ron; Carr, Zak; MacLean, Matthew; Dufrene, Aaron; Mehta, Manish

    2016-01-01

    This paper describes the Tunable Diode Laser Absorption Spectroscopy (TDLAS) measurement of several water transitions that were interrogated during a hot-fire testing of the Space Launch Systems (SLS) sub-scale vehicle installed in LENS II. The temperature of the recirculating gas flow over the base plate was found to increase with altitude and is consistent with CFD results. It was also observed that the gas above the base plate has significant velocity along the optical path of the sensor at the higher altitudes. The line-by-line analysis of the H2O absorption features must include the effects of the Doppler shift phenomena particularly at high altitude. The TDLAS experimental measurements and the analysis procedure which incorporates the velocity dependent flow will be described.

  5. A simple method for the estimation of laser absorptivity using heat-sensitive paints

    The emergence of high-power diode laser technology has paved the way for the widespread integration of laser processing into metal-cutting machine tools. Such integration is of significant benefit not just in terms of better logistics and work flow but also enhanced process capability and flexibility, and part quality. This is particularly true in the batch manufacture of high-value components, wherein it is essential to employ mathematical models to formulate and optimize operating parameters. Consequently, there is an industrial need for a simple and inexpensive technique for the rapid estimation of the laser absorptivity of a surface, which is of critical influence in the effective practical application of process models. To this end, this design note proposes a method that involves an analytical model and a novel experimental technique based on temperature-indicating paints, for estimating the absorptivity of a surface. (technical design note)

  6. Coherence in the presence of absorption and heating in a molecule interferometer.

    Cotter, J P; Eibenberger, S; Mairhofer, L; Cheng, X; Asenbaum, P; Arndt, M; Walter, K; Nimmrichter, S; Hornberger, K

    2015-01-01

    Matter-wave interferometry can be used to probe the foundations of physics and to enable precise measurements of particle properties and fundamental constants. It relies on beam splitters that coherently divide the wave function. In atom interferometers, such elements are often realised using lasers by exploiting the dipole interaction or through photon absorption. It is intriguing to extend these ideas to complex molecules where the energy of an absorbed photon can rapidly be redistributed across many internal degrees of freedom. Here, we provide evidence that center-of-mass coherence can be maintained even when the internal energy and entropy of the interfering particle are substantially increased by absorption of photons from a standing light wave. Each photon correlates the molecular center-of-mass wave function with its internal temperature and splits it into a superposition with opposite momenta in addition to the beam-splitting action of the optical dipole potential. PMID:26066053

  7. Coronal heating by the resonant absorption of Alfven waves - Importance of the global mode and scaling laws

    Steinolfson, Richard S.; Davila, Joseph M.

    1993-01-01

    Numerical simulations of the MHD equations for a fully compressible, low-beta, resistive plasma are used to study the resonance absorption process for the heating of coronal active region loops. Comparisons with more approximate analytic models show that the major predictions of the analytic theories are, to a large extent, confirmed by the numerical computations. The simulations demonstrate that the dissipation occurs primarily in a thin resonance layer. Some of the analytically predicted features verified by the simulations are (a) the position of the resonance layer within the initial inhomogeneity; (b) the importance of the global mode for a large range of loop densities; (c) the dependence of the resonance layer thickness and the steady-state heating rate on the dissipation coefficient; and (d) the time required for the resonance layer to form. In contrast with some previous analytic and simulation results, the time for the loop to reach a steady state is found to be the phase-mixing time rather than a dissipation time. This disagreement is shown to result from neglect of the existence of the global mode in some of the earlier analyses. The resonant absorption process is also shown to behave similar to a classical driven harmonic oscillator.

  8. Regional Climate Zone Modeling of a Commercial Absorption Heat Pump Hot Water Heater Part 1: Southern and South Central Climate Zones

    Geoghegan, Patrick J [ORNL; Shen, Bo [ORNL; Keinath, Christopher M. [Stone Mountain Technologies, Inc., Johnson City; Garrabrant, Michael A. [Stone Mountain Technologies, Inc., Johnson City

    2016-01-01

    Commercial hot water heating accounts for approximately 0.78 Quads of primary energy use with 0.44 Quads of this amount from natural gas fired heaters. An ammonia-water based commercial absorption system, if fully deployed, could achieve a high level of savings, much higher than would be possible by conversion to the high efficiency nonheat-pump gas fired alternatives. In comparison with air source electric heat pumps, the absorption system is able to maintain higher coefficients of performance in colder climates. The ammonia-water system also has the advantage of zero Ozone Depletion Potential and low Global Warming Potential. A thermodynamic model of a single effect ammonia-water absorption system for commercial space and water heating was developed, and its performance was investigated for a range of ambient and return water temperatures. This allowed for the development of a performance map which was then used in a building energy modeling software. Modeling of two commercial water heating systems was performed; one using an absorption heat pump and another using a condensing gas storage system. The energy and financial savings were investigated for a range of locations and climate zones in the southern and south central United States. A follow up paper will analyze northern and north/central regions. Results showed that the system using an absorption heat pump offers significant savings.

  9. The effects of heat on skin barrier function and in vivo dermal absorption.

    Oliveira, Gabriela; Leverett, Jesse C; Emamzadeh, Mandana; Lane, Majella E

    2014-04-10

    Enhanced delivery of ingredients across the stratum corneum (SC) is of great interest for improving the efficacy of topically applied formulations. Various methods for improving dermal penetration have been reported including galvanic devices and micro-needles. From a safety perspective it is important that such approaches do not compromise SC barrier function. This study investigates the influence of topically applied heat in vivo on the dermal uptake and penetration of a model active, allantoin from gel and lotion formulations. A custom designed device was used to deliver 42°C for 30s daily to human subjects after application of two formulations containing allantoin. The results were compared with sites treated with formulations containing no active and no heat, and a control site. In addition to penetration of allantoin, the integrity of the SC was monitored using trans-epidermal water loss (TEWL) measurements. The results showed that just 30s of 42°C topically applied heat was enough to cause significantly more penetration of allantoin from the lotion formulation compared with no application of heat. TEWL data indicated that the integrity of the skin was not compromised by the treatment. However, the application of heat did not promote enhanced penetration of the active from the gel formulation. Vehicle composition is therefore an important factor when considering thermal enhancement strategies for targeting actives to the skin. PMID:24445121

  10. Conversion of industrial compression cooling to absorption cooling in an integrated district heating and cooling system

    Vilafranca Manguán, Ana

    2008-01-01

    Astra Zeneca plant in Gärtuna has many compression cooling machines for comfort that consume about 11.7 GWh of electricity per year. Many of the cooling machines are old; due to the increase of production of the plant, cooling capacity was limited and new machines have been built. Now, the cooling capacity is over-sized. Söderenergi is the district heating plant that supplies heating to Astra Zeneca plant. Due to the strict environmental policy in the energy plant, last year, a bio-fuelled CH...

  11. Effects of Slip and Heat Generation/Absorption on MHD Mixed Convection Flow of a Micropolar Fluid over a Heated Stretching Surface

    Mostafa Mahmoud

    2010-01-01

    Full Text Available A theoretical analysis is performed to study the flow and heat transfer characteristics of magnetohydrodynamic mixed convection flow of a micropolar fluid past a stretching surface with slip velocity at the surface and heat generation (absorption. The transformed equations solved numerically using the Chebyshev spectral method. Numerical results for the velocity, the angular velocity, and the temperature for various values of different parameters are illustrated graphically. Also, the effects of various parameters on the local skin-friction coefficient and the local Nusselt number are given in tabular form and discussed. The results show that the mixed convection parameter has the effect of enhancing both the velocity and the local Nusselt number and suppressing both the local skin-friction coefficient and the temperature. It is found that local skin-friction coefficient increases while the local Nusselt number decreases as the magnetic parameter increases. The results show also that increasing the heat generation parameter leads to a rise in both the velocity and the temperature and a fall in the local skin-friction coefficient and the local Nusselt number. Furthermore, it is shown that the local skin-friction coefficient and the local Nusselt number decrease when the slip parameter increases.

  12. Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

    Martin, Marcel Nations; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George

    2013-01-01

    A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions.

  13. Thermoeconomic analysis of a low-temperature multi-effect thermal desalination system coupled with an absorption heat pump

    This study presents a thermal and economic performance analysis of a LT-MEE (low-temperature multi-effect evaporation) water desalination system coupled with an LiBr-H2O ABHP (absorption heat pump). A 60-78% water production increase over a stand-alone LT-MEE run at the same heat source conditions can be obtained owing to the coupling. A detailed thermodynamic sensitivity analysis of the ABHP-MEE is performed. Although ABHP is usually considered to be more efficient than an EHP (ejector heat pump), we also compare the thermal performance of the ABHP-MEE with an integrated EHP-MEE system. The results show that the ABHP has a more favorable thermal performance than the EHP only in certain parameters ranges. The reasons and these parameters ranges are discussed. The economic analysis of the ABHP-MEE shows that the capital cost of the ABHP accounts for a very small part of the water cost, and when designing an ABHP for an existing MEE unit, the parameters selection of an ABHP for lower water cost is consistent with that for better thermal performance. The unit steam cost is an important factor in determining whether the ABHP-MEE or the EHP-MEE is economically favorable, with the influence discussed. Also, a recommended general procedure for economic comparison between ABHP-MEE and EHP-MEE is outlined.

  14. ICRF heating and wave generation in the ATC tokamak. Part 1: wave generation, propagation and absorption

    Experimental results and their theoretical interpretations of rf heating experiments in the ion cyclotron range of frequencies are presented. The presentation is in two parts, with this part describing the experimental facilities and characteristics of fast compressional Alfven waves in the tokamak, and a subsequent paper which will deal with the pricipal heating results. It is shown that a simple coupling structure which consists essentially of a semi-circular metal strip and a pair of bumper limiters is sufficient to efficiently couple rf power to the plasma. The major part of the coupled power is radiated as the fast wave, and there is no evidence that parasitic loading, if any, accounts for a significant amount of the power. A coupling efficiency (net coupled power/incident power) in excess of 90% is routinely obtained

  15. Bleaching absorption fronts and beam propagation in laser-heated solenoids

    It is shown that the propagation velocity of bleaching laser-driven heating waves in the supersonic mode is governed by the requirement that the bleached plasma maintains an optical thickness of unity. It is proposed that in the case where the bleached plasma is confined by very large magnetic fields, the diameter of the plasma column may self-regulate so that the bleaching wave propagates at the Alfven velocity

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

    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%.

  17. Candidate chemical systems for air cooled, solar powered, absorption air conditioner design. Part II. Solid absorbents, high latent heat refrigerants

    Biermann, W. J.

    1978-04-01

    Work done in attempting to qualify absorption refrigeration systems based on refrigerants with intermediate latent heats of vaporization is summarized. In practice, these comprise methanol, ammonia, and methylamine. A wide variety of organic substances, salts, and mixtures were evaluated in as systematic a manner as possible. Several systems of interest are described. The system, LiClO/sub 3/--LiBr--H/sub 2/O, is a good back up system to our first choice of an antifreeze additive system, and thermodynamically promising but subject to some inconvenient materials limitations. The system, LiBr/ZnBr/sub 2/--methanol, is thermodynamically promising but requires additional kinetic qualification. Chemical stability of the system, LiCNS--ammonia/methylamine with various other third components, does not appear to be adequate for a long-lived system.

  18. Technoeconomic evaluation of trigeneraton plant: Gas turbine performance, absorption cooling and district heating

    Polyzakis, Apostolos

    2006-01-01

    This PhD thesis is a demand led study taking into account changes in ambient conditions and power settings of a tri-generation power plant. Includes an evaluation tool for combined heat, cooling and power generation plant. The thesis is based on an overall technical-economic analysis of the tri-generation system, including: 1. Energy demand analysis and evaluation of actual tri-generation case studies. 2. Modelling of the prime mover (Gas Turbine, GT) 3. Modelling of the abs...

  19. 热应激对肉鸡消化吸收功能的影响%Effect of Heat Stress on Digestion and Absorption Function of Broilers

    温超; 吴迪; 周岩民

    2009-01-01

    Heat stress negatively influences the performance of broilers mainly by reducing the feed intake and depressing the digestion and absorption function.The article reviewed the effects of heat stress on nutrient digestion and absorption, digestive enzyme activity and digestive organs of broilers.It implied that performance of broilers could be increased by improving their digestion and absorption function during heat stress.%热应激导致鸡采食量减少和消化吸收功能下降,是影响鸡生产性能的重要因素之一.综述了热应激对肉鸡消化酶活性、消化器官和营养物质消化吸收等的影响,为生产实践中采取有效措施缓解热应激提供参考依据.

  20. Performance analysis of the single-stage absorption heat transformer using a new working pair composed of ionic liquid and water

    The performance simulation of a single-stage absorption heat transformer using a new working pair composed of ionic liquids, 1-ethyl-3-methylimidazolium dimethylphosphate, and water (H2O + [EMIM][DMP]), was performed based on the thermodynamic properties of the new working pair and on the mass and energy balance for each component of the system. In order to evaluate the new working pair, the simulation results were compared with those of aqueous solution of lithium bromide (H2O + LiBr), Trifluoroethanol (TFE) + tetraethylenglycol dimethylether (E181). The results indicate that when generation, evaporation, condensing and absorption temperatures are 90 °C, 90 °C, 35 °C and 130 °C, the coefficients of performance of the single-stage absorption heat transformer using H2O + LiBr, H2O + [EMIM][DMP] and TFE + E181 as working pairs will reach 0.494, 0.481 and 0.458 respectively. And the corresponding exergy efficiency will reach 0.64, 0.62 and 0.59, respectively. Meanwhile the available heat outputs for per unit mass of refrigerant are 2466 kJ/kg, 2344 kJ/kg and 311 kJ/kg, respectively. The above excellent cycle performance together with the advantages of negligible vapor pressure, no crystallization and more weak corrosion tendency to iron-steel materials may make the new working pair better suited for the industrial absorption heat transformer. - Highlights: ► The cycle performance of the single-stage absorption heat transformer was simulated. ► Water and 1-ethyl-3-methylimidazolium dimethylphosphate was used as new working pair. ► Water and 1-ethyl-3-methylimidazolium dimethylphosphate are entirely miscible. ► The COP and exergy efficiency for this new working pairs were 0.481 and 0.62. ► The new working pairs has potential application to absorption heat transformer.

  1. Effect of heat treatment on the infrared absorption spectra of strontium-sodium-borosilicate glass

    Infrared absorption spectra of the prepared strontium-sodium-borosilicate glass (SiO2 80%-Na2O 12.5%-B2O3 5%-SrO 2.5%) are studied in the frequency range 200-4000 cm-1, where strontium oxide was introduced on partial replacement of soda in sodium-borosilicate glass, to show the effect of divalent metal oxide introduced on the structural units SiO4, BO4, and BO3 within the network structure of strontium-sodium-borosilicate glass, in the temperature range 27-800 degC. The deformation of SiO4 tetrahedra is investigated by using the baseline method, the temperature dependence of the relative integrated intensity, the relaxation time, and rotational energy barrier of this glass proved that the glassy phase is transformed to crystalline phase at 500 degC. A slight shift occurs in the strongest bands of SiO4 tetrahedra to higher frequencies, with temperature increase, which indicates an increase in the force constants between the components of the glass network structure. The increase of the absorbance in the temperature range 600-800 degC indicates strengthening of the SiO4 bonds. (author)

  2. Chemical reaction and radiation absorption effects on the flow and heat transfer of a nanofluid in a rotating system

    Venkateswarlu, B.; Satya Narayana, P. V.

    2015-03-01

    The aim of this paper is to study the effects of radiation absorption and chemical reaction on MHD free convection heat transfer flow of a nanofluid bounded by a semi-infinite flat plate in a rotating frame of reference. The plate is assumed to oscillate in time with steady frequency so that the solutions of the boundary layer are the similar oscillatory kind. The entire system rotates about the axes normal to the plate. The dimensionless governing differential equations for this investigation are solved analytically using perturbation method. The effects of various important parameters entering into the problem on velocity, temperature, skin friction and Nusselt number within the boundary layer are discussed for Cu-water-based nanofluid with the help of graphs. The predicted consequences obviously point out that the presence of nanoparticles in the base fluid improves the heat transfer process significantly. The results also show that the values of Nusselt number in case of nanofluid are more pronounced than that of micropolar fluid.

  3. Absorption heat pump integrated in an effluent purification system; Bomba de calor por absorcion integrada a un sistema de purificacion de efluentes

    Santoyo, Socrates; Siqueiros, Javier; Heard, Christopher; Santoyo, Edgar [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    The results derived of the integration of an absorption heat pump to an industrial effluents purification system, are presented. The advantages of these heat pumps with respect to heat pumps by mechanical compression of vapor, as well as the advantages in using absorption heat pumps in simple distillation systems, are mentioned. Finally, a description is made of the equipment designed and built, as well as the results obtained in a preliminary test. [Espanol] Se presentan los resultados derivados de la integracion de una bomba de calor por absorcion a un sistema de purificacion de efluentes industriales. Se mencionan las ventajas de este tipo de bombas de calor con respecto a las de calor por compresion mecanica de vapor, asi como las ventajas de usar bombas de calor en sistemas de destilacion simple. Finalmente, se describe el equipo disenado y construido, asi como los resultados obtenidos de una prueba preliminar.

  4. Influence of Variable Permeability and Radiation Absorption on Heat and Mass Transfer in MHD Micropolar Flow over a Vertical Moving Porous Plate

    Harish Babu, D.; P.V. Satya Narayana

    2013-01-01

    An analysis of unsteady free convection with heat and mass transfer flow for a micropolar fluid through a porous medium with a variable permeability bounded by a semi-infinite vertical plate in the presence of heat generation, thermal radiation, first-order chemical reaction, and the radiation absorption is reported. The plate is assumed to move with a constant velocity in the direction of fluid flow. A uniform magnetic field acts perpendicular to the porous surface which absorbs micropolar f...

  5. Co-production of pyrolysis oil and district cooling in biomass-based CHP plants: Utilizing sequential vapour condensation heat as driving force in an absorption cooling machine

    The ever-increasing demand for cooling requires new and sustainable ways of producing it. Absorption cooling is one such well-known technique that can be employed, the driving force in which is heat. When a flash pyrolysis process, with sequential vapour condensation, is integrated into a biomass-based combined heat and power plant (CHP plant), excess heat may arise in the condensers. This study demonstrates the utilization of this excess heat in an absorption cooling machine for producing district cooling. The maximum boiler load in the used CHP plant was 80 MW: the excess condenser heat created during the period June–August was 6.4 MW, which resulted in the production of 5 MW district cooling. The production of electrical power increased by 8.6% on a yearly basis, with a base load production during June–August of 2.8 MW. Using an absorption cooling machine increases the energy conversion efficiency of the CHP plant with an integrated pyrolysis process by 1.3% on a yearly basis; the energy efficiency of the pyrolysis process alone increases by 6%. An increased utilization of the condenser heat for district cooling is possible at an almost constant overall energy conversion efficiency and is demonstrated with two additional cases. - Highlights: • Energy enhancement of a biomass-based CHP plant with integrated pyrolysis process. • Simulation of a single-stage absorption cooling cycle in CHEMCAD. • Utilizing waste condenser heat for district cooling production in three cases. • Simulation of a plant with productions of heat, power, cooling and bio-oil

  6. A two-phase theoretical study of Al2O3-water nano-fluid flow inside a concentric pipe with heat generation/absorption

    Convective heat transfer and pressure drop characteristics of Al2O3-water nano-fluid inside a concentric pipe with constant heat flux boundary conditions at the both walls is investigated theoretically. The employed model for nano-fluid includes the two-phase modified Buongiorno model that fully accounts for the effects of nanoparticle volume fraction distribution. Due to the nanoparticles migration in the fluid, the no-slip condition of the fluid-solid interface at the pipe walls is abandoned in favor of a slip condition which appropriately represents the non-equilibrium region near the interface. Governing equations were transformed into a system of ordinary ones via the similarity variables and solved numerically. The effects of heat generation/absorption σ, slip parameter λ, and heat flux ratio e on nanoparticle volume fraction, velocity, temperature, heat transfer coefficient at both walls, and the dimensionless pressure gradient have been investigated in detail. The results obtained indicated that the nanoparticles move from the wall with higher heating energy towards the wall with lower heating energy (along the temperature gradient) due to the thermo-phoretic force. This non-uniform distribution of nanoparticles at the cross section of the pipe, pushes the peak of the axial velocity from the wall with lower heating energy towards the wall with higher heating energy. In addition, slip velocity at the pipe walls enhances heat transfer coefficient and increase the dimensionless pressure gradient ratio. Moreover, the changes of the heat transfer coefficient enhancement in the case of heat generation is much more that in the case of heat absorption, for low values of ratio of Brownian diffusivity to thermo-phoretic diffusivities NBT. (authors)

  7. Experimental studies on heat and mass transfer performance of a coiled tube absorber for R134a-DMAC based absorption cooling system

    Mohideen, S.T. [Institute of Road and Transport Technology, Erode, Tamil Nadu (India); Renganarayanan, S. [Institute for Energy Studies, Anna University, Chennai, Tamil Nadu (India)

    2008-11-15

    Absorber is an important component in vapor absorption refrigeration system and its performance has greater influence in overall efficiency of absorption machines. Falling film heat and mass transfer in an absorber is greatly influenced by fluid properties, geometry of heat exchanger and its operating parameters. This paper presents on the results of experimental studies on the heat and mass transfer characteristics of a coiled tube falling film absorber, using 1,1,1,2-Tetrafluroethane(R-134a) and N-N Dimethyl Acetamide (DMAC) as working fluids. The effects of film Reynolds number, inlet solution temperature and cooling water temperature on absorber heat load, over all heat transfer coefficient and mass of refrigerant absorbed are presented and discussed. Normalized solution and coolant temperature profiles and refrigerant mass absorbed along the height of absorber are also observed from the experimental results. The optimum over all heat transfer coefficient for R-134a-DMAC solution found to be 726 W/m{sup 2}K for a film Reynolds number of 350. The R-134a vapour absorption rate is maximum in the normalized coil height of 0.6 to 1. (orig.)

  8. Improvement of the raw gas drying process in olefin plants using an absorption cooling system driven by quench oil waste heat

    The raw gas (RG) in olefin plants is usually dried by triethyleneglycol absorption of the gas humidity. As low temperatures favour the absorption process, a tower cooling water system is conventionally used to reduce the raw gas temperature. However, in this case, the ambient temperature heavily influences the RG temperature, and at very high ambient temperatures, the efficiency of the drying process is too low. The objective of this paper is to propose a new cooling system that recovers part of the waste heat contained in the quench oil to improve the drying process of raw gas in olefin plants. This cooling system consists of a single effect water/LiBr absorption system, which produces chilled water at 10 deg C, and an additional chilled water/raw gas heat exchanger. The cooling water is used in parallel to dissipate heat in the absorption chiller and also as the first stage for cooling the raw gas before the chilled water is used. The technical performance of the new raw gas cooling system is compared with that of the conventional system using a cooling system design for a typical size olefin plant. The proposed system can run the drying process at the required optimised temperature, eliminate the dependence of the process on ambient temperature and use waste heat that would otherwise be dissipated in some form, as it is not useful for other applications inside the plant

  9. Development of a single-family absorption chiller for use in a solar heating and cooling system, phase 3, volume 2

    Reimann, R. C.; Biermann, W. J.

    1984-10-01

    Supporting information is presented on: properties of a chemical system for solar fired, air-cooled absorption equipment, air-side performance of a one-inch tube, absorber plate-fin coil, listings of the programs used for simulation and data reduction, and evaluation of the Carrier three-tone chiller in an integrated heating and cooling system.

  10. Determination of trace and minor elements in alloys by atomic-absorption spectroscopy using an induction-heated graphite-well furnace as atom source-II.

    Ashy, M A; Headridge, J B; Sowerbutts, A

    1974-06-01

    Results are presented for the atomic-absorption spectrophotometric determination of zinc in aluminium and aluminium-silicon alloys, and aluminium, antimony and tin in steels, by means of solid samples dropped into an induction-heated graphite-well furnace to produce the atomic vapour. PMID:18961510

  11. An outdoor investigation of the absorption degradation of single-junction amorphous silicon photovoltaic module due to localized heat/hot spot formation

    Osayemwenre Gilbert O; Meyer Edson L; Mamphweli Sampson

    2016-04-01

    This paper investigates the absorbance degradation of single-junction amorphous silicon (a-Si:H) photovoltaic (PV) module, due to the presence of localized heat. The decrease in optical density is a huge challenge due to the long-term degradation of PV modules. The reduction in solar cell optical density causes a decline in its conversion efficiency. This decreases the photogenerating current, hence reduces the effective efficiency of the PV device. An infrared thermography was used for mapping the module temperature profile. Fourier transform infrared spectroscopy (FTIR) was used for the absorption characterization. The rationale behind the outdoor deployment was to deduce a practical effect of hot spot formation on the module’s absorption ability.The results show a direct correlation between localized heat and the absorption degradation.

  12. Absorption of solar energy heats up our planet's surface and the atmosphere and makes life for us po

    2002-01-01

    Credit: Image courtesy Barbara Summey, NASA Goddard Visualization Analysis Lab, based upon data processed by Takmeng Wong, CERES Science Team, NASA Langley Research Center Satellite: Terra Sensor: CERES Image Date: 09-30-2001 VE Record ID: 11546 Description: Absorption of solar energy heats up our planet's surface and the atmosphere and makes life for us possible. But the energy cannot stay bound up in the Earth's environment forever. If it did then the Earth would be as hot as the Sun. Instead, as the surface and the atmosphere warm, they emit thermal longwave radiation, some of which escapes into space and allows the Earth to cool. This false-color image of the Earth was produced on September 30, 2001, by the Clouds and the Earth's Radiant Energy System (CERES) instrument flying aboard NASA's Terra spacecraft. The image shows where more or less heat, in the form of longwave radiation, is emanating from the top of Earth's atmosphere. As one can see in the image, the thermal radiation leaving the oceans is fairly uniform. The blue swaths across the central Pacific represent thick clouds, the tops of which are so high they are among the coldest places on Earth. In the American Southwest, which can be seen in the upper righthand corner of the globe, there is often little cloud cover to block outgoing radiation and relatively little water to absorb solar energy. Consequently, the amount of outgoing radiation in the American Southwest exceeds that of the oceans. Also, that region was experiencing an extreme heatwave when these data were acquired. Recently, NASA researchers discovered that incoming solar radiation and outgoing thermal radiation increased in the tropics from the 1980s to the 1990s. (Click to read the press release .) They believe that the reason for the unexpected increase has to do with an apparent change in circulation patterns around the globe, which effectively reduced the amount of water vapor and cloud cover in the upper reaches of the atmosphere

  13. Electromagnetic energy absorption potential and microwave heating capacity of SiC thin films in the 1-16 GHz frequency range

    We report on the electromagnetic (EM) absorption potential and microwave heating capacity of amorphous hydrogenated silicon carbide thin films (a-SiC:H) in the 1-16 GHz frequency domain. a-SiC:H thin films with typical thickness of 1 μm were deposited by plasma enhanced chemical vapor deposition on [1 0 0] undoped silicon substrates, and exhibit a deep EM absorption - up to 96% of the total EM energy irradiation - which is systematically converted into heat. Two-wavelength pyrometer tests show that temperatures exceeding 2000 K can be reached in a very short time, less than 100 s exposure to microwaves, showing a promising potential for specific microwave heating applications.

  14. Heat Generation/Absorption Effects in a Boundary Layer Stretched Flow of Maxwell Nanofluid: Analytic and Numeric Solutions.

    Muhammad Awais

    Full Text Available Analysis has been done to investigate the heat generation/absorption effects in a steady flow of non-Newtonian nanofluid over a surface which is stretching linearly in its own plane. An upper convected Maxwell model (UCM has been utilized as the non-Newtonian fluid model in view of the fact that it can predict relaxation time phenomenon which the Newtonian model cannot. Behavior of the relaxations phenomenon has been presented in terms of Deborah number. Transport phenomenon with convective cooling process has been analyzed. Brownian motion "Db" and thermophoresis effects "Dt" occur in the transport equations. The momentum, energy and nanoparticle concentration profiles are examined with respect to the involved rheological parameters namely the Deborah number, source/sink parameter, the Brownian motion parameters, thermophoresis parameter and Biot number. Both numerical and analytic solutions are presented and found in nice agreement. Comparison with the published data is also made to ensure the validity. Stream lines for Maxwell and Newtonian fluid models are presented in the analysis.

  15. Experiment on heat transfer and absorption performance enhancement for binary nanofluids (NH{sub 3}/H{sub 2}O + Nano-Particles)

    Lee, Jin Ki; Jung, Chung Woo; Kang, Yong Tae [Kyunghee Univ., Yongin (Korea, Republic of)

    2008-09-15

    The objectives of this paper are to examine the effect of nano-particles on the pool type absorption heat transfer enhancement and to find the optimal conditions to design a highly effective compact absorber for ammonia/water absorption system. The effect of AL{sub 2}O{sub 3} nano-particles and Carbon NanoTube(CNT) on the absorption performance is studied experimentally. The experimental ranges of the key parameters are 20% of ammonia concentration, 0{approx}0.08 vol% (volume fraction) of CNT particles, and 0{approx}0.06 vol% of Al{sub 2}O{sub 3} nano-particles. For the ammonia/water nanofluids, the heat transfer rate and absorption rate with 0.02 vol% Al{sub 2}O{sub 3} nano-particles were found to be 29% and 18% higher than those without nano-particles respectively. It is recommended that the concentration of 0.02 vol% of Al{sub 2}O{sub 3} nano-particles be the best candidate for ammonia/water absorption performance enhancement.

  16. Effects of Radiation and Heat Generation/Absorption on MHD Free Convective Heat Transfer of Power-Law Non-Newtonian Fluids Along a Power-Law Stretching Sheet with Uniform Surface Heat Flux

    M.A. Samad

    2013-01-01

    Full Text Available An analysis is carried out to investigate the effects of MHD free convection heat transfer of power-law non-Newtonian fluids along a stretching sheet. This has been done under the simultaneous action of suction, heat generation/absorption, thermal radiation and uniform transverse magnetic field. The stretching sheet is assumed to continuously moving with a power-law velocity and maintaining a uniform surface heat flux. The governing nonlinear partial differential equations are transformed into a system of nonlinear ordinary differential equations using appropriate similarity transformations. The resulting non-linear equations are solved numerically using Nachtsheim-Swigert shooting iterative technique along with sixth order Runge-Kutta integration scheme. Numerical results for the non-dimensional velocity and temperature profiles are shown graphically and discussed. The effects of skin-friction coefficient and the local Nusselt number which are of physical and engineering interest are studied and presented graphically as well as in the form of tables for the variation of different physically important parameters. A comparison of the present study is also performed with the previously published study and found excellent agreement.

  17. Open absorption heat pump and application in flue gas waste heat recovering%开式吸收式热泵及在烟气余热回收中的应用

    贾红书; 付林; 张世钢

    2013-01-01

    开式吸收式热泵具有结构简单、低品位热能驱动、省电等优点,推广利用该技术,对解决目前面临的城市热源不足及提高工业能源利用效率具有重要意义,但运行中存在设备腐蚀、不凝性气体等问题。本文总结了国内外开式吸收式热泵的研究进展,其应用领域涉及供暖、空调、制冷及工业生产,处理气流包括空气、燃烧后烟气,驱动热源包括太阳能、生物质锅炉、天然气锅炉及电厂锅炉等集中热源和分布式能源,结构形式多样化;简述了开式吸收式热泵在工业余热,特别是天然气锅炉烟气余热和湿法脱硫电厂饱和烟气潜热和水回收领域中的应用;分析了运行中出现的溶液腐蚀、不凝气气体及设备堵塞问题,并提出了解决方案。%Simple structure and low grade heat energy requirement are great advantages of open absorption heat pump. Proper use of this technology is important to solve the city heat shortage and improve energy efficiencies in industries. However,equipment corrosion,non-condensable gas and other issues often prevent the application of open absorption pump. This paper summarized the domestic and international research progressed of the open absorption heat pump. It can be used in heating,air conditioning,refrigeration and other industrial processes. Processing media including air, flue gas after combustion,driving heat source can be concentrated heat source and distributed energy, such as solar energy,biomass boiler,gas boiler and power plant boiler. Structures can be different based on heat sources and purposes of applications. Applications of open absorption heat pump in the industrial waste heat recovery,especially flue gas waste heat recovery were also briefly overviewed. The causes and possible solutions to corrosion and non-condensable gas plugging were analyzed as well.

  18. Approximate Solutions of a Higher Order MHD Flow of a Uniformly Stretched Vertical Permeable Surface in the Presence of Heat Generation/Absorption which Resulted from a Quadratic Reaction

    O. K. Koriko

    2010-01-01

    Full Text Available Higher order MHD flow of a uniformity stretched vertical permeable surface in the presence of heat generation/absorption which resulted from a quadratic reaction was studied. The resulting coupled nonlinear partial differential equations is solved by asymptotic expansion. It was discovered that the maximum value of velocity occurs in the body of the fluid close to the surface not at the surface. The effect of heat generated on the velocity profile is more pronounced than that of heat absorption.

  19. Hydromagnetic free convection of a particulate suspension from a permeable inclined plate with heat absorption for non-uniform particle-phase density

    Ramadan, Hasan M. [Kuwait Airways Corporation, Operations Department, Salmeya (Kuwait); Chamkha, Ali J. [Department of Mechanical Engineering, Kuwait University, Safat (Kuwait)

    2003-06-01

    The problem of steady, laminar, free convection flow of a particulate suspension over an infinite, permeable, inclined, and isothermal flat plate in the presence of a transverse magnetic field and fluid heat absorption effects is studied numerically. The problem accounts for particulate viscous effects which are absent from most two-phase models. An analytical solution is developed for the particle-phase density distribution and numerical solutions for the velocity and temperature profiles of both phases are obtained by using an implicit and iterative finite-difference method. A parametric study illustrating the influence of the magnetic field, heat absorption effects and particle loading is conducted. The obtained results for velocity, temperature and skin-friction coefficients for both phases as well as the Nusselt number are illustrated graphically to show the features of the solution. (orig.)

  20. Reduction in biomass burning aerosol light absorption upon humidification: Roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

    lewis, Kristen A.; Arnott, W. P.; Moosmuller, H.; Chakrabarti, Raj; Carrico, Christian M.; Kreidenweis, Sonia M.; Day, Derek E.; Malm, William C.; Laskin, Alexander; Jimenez, Jose L.; Ulbrich, Ingrid M.; Huffman, John A.; Onasch, Timothy B.; Trimborn, Achim; Liu, Li; Mishchenko, M.

    2009-11-27

    Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used are Montana ponderosa pine (Pinus ponderosa), southern California chamise (Adenostoma fasciculatum), and Florida saw palmetto (Serenoa repens). Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients reveal a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: 1. Shielding of inner monomers after particle consolidation or collapse with water uptake; 2. The contribution of mass transfer through evaporation and condensation at high relative humidity to the usual heat transfer pathway for energy release by laser heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

  1. MHD viscous Casson fluid flow and heat transfer with second-order slip velocity and thermal slip over a permeable stretching sheet in the presence of internal heat generation/absorption and thermal radiation

    Megahed, Ahmed M.

    2015-04-01

    This article is devoted to describing the boundary layer flow and heat transfer for an electrically conducting Casson fluid over a permeable stretching surface with second-order slip velocity model and thermal slip conditions in the presence of internal heat generation/absorption and thermal radiation. The basic equations governing the flow and heat transfer are in the form of partial differential equations; the same have been reduced to a set of highly non-linear ordinary differential equations by applying suitable similarity transformations. Exact solution corresponding to momentum equation is obtained, and, in the case of no slip conditions, we get the exact solutions for both momentum and energy equation. The resulting similarity equations are solved numerically by shooting method. Comparisons with previously published work are performed and the results are found to be in excellent agreement. In the present work the effect of magnetic parameter, suction/injection parameter, Casson parameter, slip parameters, radiation parameter, internal heat generation/absorption parameter and the Prandtl number on flow and heat transfer characteristics have been discussed. Also, the local skin-friction coefficient and the local Nusselt number at the sheet are computed and discussed. It is found that the temperature rises to a higher value when the Casson parameter increases but the reverse is true for the velocity distribution. Finally, increasing the velocity and thermal slip parameters makes the rate of heat transfer decrease.

  2. Performance analysis of absorption heat transformer cycles using ionic liquids based on imidazolium cation as absorbents with 2,2,2-trifluoroethanol as refrigerant

    Highlights: • TFE + [emim][BF4] (or [bmim][BF4]) absorption heat transformer cycles are studied. • Influence of various operating conditions on cycle’s performance is investigated. • Performance comparisons with H2O + LiBr and TFE + TEGDME cycles are done. • Enthalpy data for TFE + [emim][BF4] (or [bmim][BF4]) liquid mixtures are calculated. • TFE + [emim][BF4] (or [bmim][BF4]) cycles have higher gross temperature lift (GTL). - Abstract: A detailed thermodynamic performance analysis of a single-stage absorption heat transformer and double absorption heat transformer cycles using new working pairs composed of ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4])) as absorbent and 2,2,2-trifluoroethanol (TFE) as refrigerant has been studied. Several performance indicators were used to evaluate and compare the performance of the cycles using the TFE + [emim][BF4] and TFE + [bmim][BF4] working pairs with the conventional H2O + LiBr and organic TFE + TEGDME working pairs. The obtained results show that the ionic liquid based working pairs are suitable candidates to replace the conventional H2O + LiBr working pairs in order to avoid the disadvantages associated with it mainly crystallization and corrosion and also they perform better (higher gross temperature lift) than TFE + TEGDME working pair at several operating conditions considered in this work

  3. Study of coupled heat and mass transfer during absorption of hydrogen in MmNi4·6Al0·4 based hydrogen storage device

    P Muthukumar; Manvendra M Umekar

    2009-04-01

    A two-dimensional numerical analysis of coupled heat and mass transfer processes in a cylindrical metal hydride reactor containing MmNi4·6Al0·4 is presented. To understand the hydrogen absorption mechanism the governing equations for energy, momentum and mass conservation and reaction kinetic equations are solved simultaneously using the finite volume method (FVM). Performance studies on MmNi4·6Al0·4 based hydrogen storage device are carried out by varying the hydrogen supply pressure, absorption (cooling fluid) temperature, overall heat transfer coefficient and hydride bed thickness. Effect of convection terms in the energy equation on hydrogen storage performance is found to be negligible. The results obtained from the computer simulation showed good agreement with the available experimental data. At the supply conditions of 30 bar and 298 K, MmNi4·6Al0·4 stores about 1·28 wt%, which is very close to the experimental value of 1·3 wt%. Overall high heat transfer coefficients are found to reduce the absorption time significantly.

  4. Hydromagnetic slip flow of water based nano-fluids past a wedge with convective surface in the presence of heat generation (or) absorption

    Rahman, M.M.; Al-Lawatia, M.A.; Eltayeb, I.A.; Al-Salti, N. [Department of Mathematics and Statistics, College of Science, Sultan Qaboos University, P.O. Box 36, P.C. 123 Al-Khod, Muscat (Oman)

    2012-07-15

    Heat transfer characteristics of a two-dimensional steady hydromagnetic slip flow of water based nano-fluids (TiO{sub 2}-water, Al{sub 2}O{sub 3}-water, and Cu-water) over a wedge with convective surface taking into account the effects of heat generation (or absorption) has been investigated numerically. The local similarity solutions are obtained by using very robust computer algebra software MATLAB and presented graphically as well as in a tabular form. The results show that nano-fluid velocity is lower than the velocity of the base fluid and the existence of the nano-fluid leads to the thinning of the hydrodynamic boundary layer. The rate of shear stress is significantly influenced by the surface convection parameter and the slip parameter. It is higher for nano-fluids than the base fluid. The results also show that within the boundary layer the temperature of the nano-fluid is higher than the temperature of the base fluid. The rate of heat transfer is found to increase with the increase of the surface convection and the slip parameters. Addition of nano-particles to the base fluid induces the rate of heat transfer. The rate of heat transfer in the Cu-water nano-fluid is found to be higher than the rate of heat transfer in the TiO{sub 2}-water and Al{sub 2}O{sub 3}-water nano-fluids. (authors)

  5. Hydromagnetic slip flow of water based nano-fluids past a wedge with convective surface in the presence of heat generation (or) absorption

    Heat transfer characteristics of a two-dimensional steady hydromagnetic slip flow of water based nano-fluids (TiO2-water, Al2O3-water, and Cu-water) over a wedge with convective surface taking into account the effects of heat generation (or absorption) has been investigated numerically. The local similarity solutions are obtained by using very robust computer algebra software MATLAB and presented graphically as well as in a tabular form. The results show that nano-fluid velocity is lower than the velocity of the base fluid and the existence of the nano-fluid leads to the thinning of the hydrodynamic boundary layer. The rate of shear stress is significantly influenced by the surface convection parameter and the slip parameter. It is higher for nano-fluids than the base fluid. The results also show that within the boundary layer the temperature of the nano-fluid is higher than the temperature of the base fluid. The rate of heat transfer is found to increase with the increase of the surface convection and the slip parameters. Addition of nano-particles to the base fluid induces the rate of heat transfer. The rate of heat transfer in the Cu-water nano-fluid is found to be higher than the rate of heat transfer in the TiO2-water and Al2O3-water nano-fluids. (authors)

  6. Evaluation of an Absorption Heat Pump to Mitigate Plant Capacity Reduction Due to Ambient Temperature Rise for an Air-Cooled Ammonia and Water Cycle: Preprint

    Air-cooled geothermal plants suffer substantial decreases in generating capacity at increased ambient temperatures. As the ambient temperature rises by 50 F above a design value of 50 F, at low brine-resource temperatures, the decrease in generating capacity can be more than 50%. This decrease is caused primarily by increased condenser pressure. Using mixed-working fluids has recently drawn considerable attention for use in power cycles. Such cycles are more readily amenable to use of absorption ''heat pumps.'' For a system that uses ammonia and water as the mixed-working fluid, this paper evaluates using an absorption heat pump to reduce condenser backpressure. At high ambient temperatures, part of the turbine exhaust vapor is absorbed into a circulating mixed stream in an absorber in series with the main condenser. This steam is pumped up to a higher pressure and heated to strip the excess vapor, which is recondensed using an additional air-cooled condenser. The operating conditions are chosen to reconstitute this condensate back to the same concentration as drawn from the original system. We analyzed two power plants of nominal 1-megawatt capacity. The design resource temperatures were 250 F and 300 F. Ambient temperature was allowed to rise from a design value of 50 F to 100 F. The analyses indicate that using an absorption heat pump is feasible. For the 300 F resource, an increased brine flow of 30% resulted in a net power increase of 21%. For the 250 F resource, the increase was smaller. However, these results are highly plant- and equipment-specific because evaluations must be carried out at off-design conditions for the condenser. Such studies should be carried out for specific power plants that suffer most from increased ambient temperatures

  7. Evaluation of an Absorption Heat Pump to Mitigate Plant Capacity Reduction Due to Ambient Temperature Rise for an Air-Cooled Ammonia and Water Cycle: Preprint

    Bharathan, D.; Nix, G.

    2001-08-06

    Air-cooled geothermal plants suffer substantial decreases in generating capacity at increased ambient temperatures. As the ambient temperature rises by 50 F above a design value of 50 F, at low brine-resource temperatures, the decrease in generating capacity can be more than 50%. This decrease is caused primarily by increased condenser pressure. Using mixed-working fluids has recently drawn considerable attention for use in power cycles. Such cycles are more readily amenable to use of absorption ''heat pumps.'' For a system that uses ammonia and water as the mixed-working fluid, this paper evaluates using an absorption heat pump to reduce condenser backpressure. At high ambient temperatures, part of the turbine exhaust vapor is absorbed into a circulating mixed stream in an absorber in series with the main condenser. This steam is pumped up to a higher pressure and heated to strip the excess vapor, which is recondensed using an additional air-cooled condenser. The operating conditions are chosen to reconstitute this condensate back to the same concentration as drawn from the original system. We analyzed two power plants of nominal 1-megawatt capacity. The design resource temperatures were 250 F and 300 F. Ambient temperature was allowed to rise from a design value of 50 F to 100 F. The analyses indicate that using an absorption heat pump is feasible. For the 300 F resource, an increased brine flow of 30% resulted in a net power increase of 21%. For the 250 F resource, the increase was smaller. However, these results are highly plant- and equipment-specific because evaluations must be carried out at off-design conditions for the condenser. Such studies should be carried out for specific power plants that suffer most from increased ambient temperatures.

  8. Analysis of the behavior of an experimental absorption heat transformer for water purification for different mass flux rates in the generator

    In the present study, first and second laws of thermodynamics have been used to analyse the performance of an experimental absorption heat transformer for water purification. Irreversibilities, coefficients of performance (COP) and exergy coefficients of performance (ECOP) were determined as function of the mass flow of hot water supplied to the generator and as function of the overall thermal specific energy consumption (OSTEC) parameter defined in this paper. The results showed that the system irreversibilities increase meanwhile the coefficients of performance and the exergy coefficient of performance decrease with an increment of the mass flow of hot water supplied to the generator. Also it was shown that the system performance is better when the production of purified water increases due to the increment of the heat recycled to the generator and evaporator. -- Highlights: ► Exergetic performance of an absorption heat transformer for purifying water to different mass flux rates in the generator. ► The irreversibilities are increasing when the mass flow rate in the generator is major. ► The mass flow rates in the generator plays a decisive role in the whole system efficiency

  9. Effects of post-heat treatment on the characteristics of chalcopyrite CuInSe2 film deposited by successive ionic layer absorption and reaction method

    The influence of annealing effects in CuInSe2 ternary films prepared by successive ionic layer absorption and reaction method has been investigated. The films have firstly been deposited on glass substrates at room temperature and then heat-treated under Ar atmosphere at various annealing temperatures. CuInSe2 films were characterized using X-ray diffraction (XRD), scanning electron microscopy, X-ray photoelectron spectra, optical absorption spectrum and Hall system. XRD results showed that the proper post-annealing process can lead to a complete formation of chalcopyrite structure CuInSe2 with high degree of preferred orientation towards (112) reflection. After annealing process, the composition of annealed films was close to the standard stoichiometry and O, Cl impurities decreased. The direct band gap increased from 0.94 to 0.98 eV and resistivity showed a big decrease with the increase of annealing temperature

  10. Reduction in biomass burning aerosol light absorption upon humidification: roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

    K. A. Lewis

    2009-07-01

    Full Text Available Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used are Montana ponderosa pine (Pinus ponderosa, southern California chamise (Adenostoma fasciculatum, and Florida saw palmetto (Serenoa repens. Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients reveal a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: 1. Shielding of inner monomers after particle consolidation or collapse with water uptake; 2. The contribution of mass transfer through evaporation and condensation at high relative humidity to the usual heat transfer pathway for energy release by laser-heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

  11. Reduction in biomass burning aerosol light absorption upon humidification: roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

    L. Liu

    2009-11-01

    Full Text Available Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used were Montana ponderosa pine (Pinus ponderosa, southern California chamise (Adenostoma fasciculatum, and Florida saw palmetto (Serenoa repens. Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients revealed a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: (1 shielding of inner monomers after particle consolidation or collapse with water uptake; (2 the lower case contribution of mass transfer through evaporation and condensation at high relative humidity (RH to the usual heat transfer pathway for energy release by laser-heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

  12. Design and Economic Potential of an Integrated High-Temperature Fuel Cell and Absorption Chiller Combined Cooling, Heat, and Power System

    Hosford, Kyle S.

    Clean distributed generation power plants can provide a much needed balance to our energy infrastructure in the future. A high-temperature fuel cell and an absorption chiller can be integrated to create an ideal combined cooling, heat, and power system that is efficient, quiet, fuel flexible, scalable, and environmentally friendly. With few real-world installations of this type, research remains to identify the best integration and operating strategy and to evaluate the economic viability and market potential of this system. This thesis informs and documents the design of a high-temperature fuel cell and absorption chiller demonstration system at a generic office building on the University of California, Irvine (UCI) campus. This work details the extension of prior theoretical work to a financially-viable power purchase agreement (PPA) with regard to system design, equipment sizing, and operating strategy. This work also addresses the metering and monitoring for the system showcase and research and details the development of a MATLAB code to evaluate the economics associated with different equipment selections, building loads, and economic parameters. The series configuration of a high-temperature fuel cell, heat recovery unit, and absorption chiller with chiller exhaust recirculation was identified as the optimal system design for the installation in terms of efficiency, controls, ducting, and cost. The initial economic results show that high-temperature fuel cell and absorption chiller systems are already economically competitive with utility-purchased generation, and a brief case study of a southern California hospital shows that the systems are scalable and viable for larger stationary power applications.

  13. An ecological concept for power supply. Heat for absorption chillers from pellet heating systems and cogeneration plants on the basis of vegetable oils; Oekologisches Konzept fuer die Energieversorgung. Waerme fuer Absorptionskaeltemaschinen aus Pellets-Heizkessel und Pflanzenoel-BHKW

    Schmid, Wolfgang

    2008-07-01

    With its new administration building at the headquarters in Neumarkt (Upper Palatinate, Northern Bavaria, Federal Republic of Germany), Bionorica AG (producer of vegetable drugs, phytopharmaka) established a building which guarantees an optimum environmental compatibility and greatest possible energy efficiency. Due to the strong organic growth of the company, the construction of the new official building led to a re-organization of the entire supply of electricity, warmth and cold at the location Neumarkt (Upper Palatinate). In the meantime, in the new energy centre there are two pellet boilers, a cogeneration plant on the basis of vegetable oil as well as four absorption refrigerators which are driven by waste heat from engines and/or heating heating.

  14. Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass

    Farah, Khaled; Hosni, Faouzi; Mejri, Arbi; Boizot, Bruno; Hafedh, Ben; Hamzaoui, Ahmed Hichem

    2014-01-01

    International audience Samples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO 3 and NaNO 3 with molar ratio of 1:99 and 5:95 for 60 min. The ion exchange process was followed by gamma irradiation in the dose range of 1–250 kGy and heating at the temperature of 550 °C for different time periods ranging from 10 to 582 min. The spectral absorption in UV–Vis range of the Ag–Na ion exchanged glass was measured and used to determine the s...

  15. Influence of thermal radiation and heat generation/absorption on MHD heat transfer flow of a micropolar fluid past a wedge considering hall and ion slip currents

    Uddin Ziya; Kumar Manoj; Harmand Souad

    2014-01-01

    In this paper a numerical model is developed to examine the effect of thermal radiation on magnetohydrodynamic heat transfer flow of a micropolar fluid past a non-conducting wedge in presence of heat source/sink. In the model it is assumed that the fluid is viscous, incompressible and electrically conducting. The Hall and ion slip effects have also been taken into consideration. The model contains highly non-linear coupled partial differential equations whi...

  16. Calculation of the radiative heat exchange in a conical cavity of complex configuration with an absorptive medium

    Surinov, Y. A.; Fedyanin, V. E.

    1975-01-01

    The generalized zonal method is used to calculate the distribution of the temperature factor on the lateral surface of a conical cavity of complex configuration (a Laval nozzle) containing an absorptive medium. The highest values of the radiation density occur on the converging part of the lateral surface of the complex conical cavity (Laval nozzle).

  17. Modeling of Artificial Neural Network for Predicting Specific Heat capacity of working fluid LiBr-H2O used in Vapor Absorption Refrigeration System

    Dheerendra Vikram Singh

    2011-05-01

    Full Text Available The objective of this work is to model an artificial neural network (ANN to predict the value of specific heat capacity of working fluid LiBr-H2O used in vapour absorption refrigeration systems. A feed forward back propagation algorithm is used for the network, which is most popular for ANN. The consistence between experimental and ANN’s approach result was achieved by a mean relative error -0.00573, sum of the squares due to error0.00321, coefficient of multiple determination R-square 0.99961and root mean square error 0.01573 for test data. These results had been achieved in Matlab environment and the use of derived equations in any programmable language for deriving the specific heat capacity of LiBr-H2O solution.

  18. Atomization in graphite-furnace atomic absorption spectrometry. Peak-height method vs. integration method of measuring absorbance: heated graphite atomizer 2100

    The signal integration technique developed and reported earlier has been used for measuring atomic absorption signals generated by the Heated Graphite Atomizer 2100. Cd, Zn, Al, Sn, Cu, Mo, and V have been selected for this study. In theory, the integration method of measuring absorbance is superior to the conventional peak-height as the measure of absorbance. In practice, integration does offer some advantages over the peak-height method of measurement; absolute sensitivity is increased by a factor of 2- to 8-fold and the linear range of the working curves is increased by a factor of up to 2. This study shows the effect of the better cell geometry of the HGA 2100 (as opposed to the Carbon Rod Atomizer 63) on the integrated absorbance signals. Modifications to the Heated Graphite Atomizer 2100 which would improve the atomization conditions beneficial to the integration method of measuring are suggested. (U.S.)

  19. Thermal and economic assessment of hot side sensible heat and cold side phase change storage combination fo absorption solar cooling system

    Choi, M. K.; Morehouse, J. H.

    An analysis of a solar assisted absorption cooling system which employs a combination of phase change on the cold side and sensible heat storage on the hot side of the cooling machine for small commercial buildings is given. The year-round thermal performance of this system for space cooling were determined by simulation and compared against conventional cooling systems in three geographic locations: Phoenix, Arizona; Miami, Florida and Washington, D.C. The results indicate that the hot-cold storage combination has a considerable amount of energy and economical savings over hot side sensible heat storage. Using the hot-cold storage combination, the optimum collector areas for Washington, D.C., Phoenix and Miami are 355 m squared, 250 m squared and 495 m squared, respectively. Compared against conventional vapor compression chiller, the net solar fractions are 61, 67 and 69 percent, respectively.

  20. Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass

    Farah, Khaled, E-mail: kafarah@gmail.com [Unité de recherche: Maîtrise et développement des techniques nucléaires à caractère pacifique, Centre National des Sciences et Technologie Nucléaires, 2020 Sidi-Thabet (Tunisia); ISTLS, University of Sousse (Tunisia); Hosni, Faouzi [Unité de recherche: Maîtrise et développement des techniques nucléaires à caractère pacifique, Centre National des Sciences et Technologie Nucléaires, 2020 Sidi-Thabet (Tunisia); Academie Militaire de Fondouk Jedid, 8012 Nabeul (Tunisia); Mejri, Arbi [Unité de recherche: Maîtrise et développement des techniques nucléaires à caractère pacifique, Centre National des Sciences et Technologie Nucléaires, 2020 Sidi-Thabet (Tunisia); Boizot, Bruno [Laboratoire des Solides Irradiés, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Hamzaoui, Ahmed Hichem [Centre National de Recherche en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Ben Ouada, Hafedh [Laboratoire des Interfaces et Matériaux Avancés, Faculté des Sciences, University of Monastir, Avenue de l’environnement, 5019 Monastir (Tunisia)

    2014-03-15

    Samples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO{sub 3} and NaNO{sub 3} with molar ratio of 1:99 and 5:95 for 60 min. The ion exchange process was followed by gamma irradiation in the dose range of 1–250 kGy and heating at the temperature of 550 °C for different time periods ranging from 10 to 582 min. The spectral absorption in UV–Vis range of the Ag–Na ion exchanged glass was measured and used to determine the states of silver prevailing in the glass during the ion exchange, the gamma irradiation and the heat treatment. The gamma irradiation induced holes and electrons in the glass structure leading to the creation of a brown colour, and silver ions trapped electrons to form silver atoms. We observed the first stage of aggregation after irradiation, as well as after heating. The silver atoms diffused and then aggregated to form nanoclusters after heating at 550 °C. A characteristic band at about 430 nm was induced. The surface Plasmon absorption of silver nanoclusters in the glass indicated that the nanoclusters radius grew between 0.9 and 1.43 nm with increasing of annealing time from 10 to 242 min and then saturated. We also found that the size of aggregates depends on the value of gamma radiation absorbed dose. Contrary to what was expected, we found that 20 kGy is the optimal absorbed dose corresponding to the larger size of the aggregates which decreases for absorbed doses above 20 kGy.

  1. Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass

    Samples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO3 and NaNO3 with molar ratio of 1:99 and 5:95 for 60 min. The ion exchange process was followed by gamma irradiation in the dose range of 1–250 kGy and heating at the temperature of 550 °C for different time periods ranging from 10 to 582 min. The spectral absorption in UV–Vis range of the Ag–Na ion exchanged glass was measured and used to determine the states of silver prevailing in the glass during the ion exchange, the gamma irradiation and the heat treatment. The gamma irradiation induced holes and electrons in the glass structure leading to the creation of a brown colour, and silver ions trapped electrons to form silver atoms. We observed the first stage of aggregation after irradiation, as well as after heating. The silver atoms diffused and then aggregated to form nanoclusters after heating at 550 °C. A characteristic band at about 430 nm was induced. The surface Plasmon absorption of silver nanoclusters in the glass indicated that the nanoclusters radius grew between 0.9 and 1.43 nm with increasing of annealing time from 10 to 242 min and then saturated. We also found that the size of aggregates depends on the value of gamma radiation absorbed dose. Contrary to what was expected, we found that 20 kGy is the optimal absorbed dose corresponding to the larger size of the aggregates which decreases for absorbed doses above 20 kGy

  2. A Cooling System for an Automobile Based on Vapour Absorption Refrigeration Cycle Using Waste Heat of an Engine.

    Satish K. Maurya; Saurabh Awasthi

    2014-01-01

    Now a days the air conditioning system of cars is mainly uses “Vapour Compression Refrigerant System” (VCRS) which absorbs and removes heat from the interior of the car that is the space to be cooled and rejects the heat to atmosphere. In vapour compression refrigerant system, the system utilizes power from engine shaft as the input power to drive the compressor of the refrigeration system, hence the engine has to produce extra work to run the compressor of the refrigerating s...

  3. Effects of soot absorption coefficient-Planck function correlation on radiative heat transfer in oxygen-enriched propane turbulent diffusion flame

    Consalvi, J. L.; Nmira, F.

    2016-03-01

    The main objective of this article is to quantify the influence of the soot absorption coefficient-Planck function correlation on radiative loss and flame structure in an oxygen-enhanced propane turbulent diffusion flame. Calculations were run with and without accounting for this correlation by using a standard k-ε model and the steady laminar flamelet model (SLF) coupled to a joint Probability Density Function (PDF) of mixture fraction, enthalpy defect, scalar dissipation rate, and soot quantities. The PDF transport equation is solved by using a Stochastic Eulerian Field (SEF) method. The modeling of soot production is carried out by using a flamelet-based semi-empirical acetylene/benzene soot model. Radiative heat transfer is modeled by using a wide band correlated-k model and turbulent radiation interactions (TRI) are accounted for by using the Optically-Thin Fluctuation Approximation (OTFA). Predicted soot volume fraction, radiant wall heat flux distribution and radiant fraction are in good agreement with the available experimental data. Model results show that soot absorption coefficient and Planck function are negatively correlated in the region of intense soot emission. Neglecting this correlation is found to increase significantly the radiative loss leading to a substantial impact on flame structure in terms of mean and rms values of temperature. In addition mean and rms values of soot volume fraction are found to be less sensitive to the correlation than temperature since soot formation occurs mainly in a region where its influence is low.

  4. Design and Economic Analysis of a Heating/Absorption Cooling System Operating with Municipal Solid Waste Digester: A Case Study of Gazi University

    Coşar, Gökhan; Pooyanfar, Mirparham; Amirabedin, Ehsan; Topal, Hüseyin

    2013-12-01

    Recovering energy from municipal solid waste (MSW) is one of the most important issues of energy management in developed countries. This raises even more interest as world fossil fuel reserves diminish and fuel prices rise. Being one of main processes of waste disposal, anaerobic digestion can be used as a means to reduce fossil fuel and electricity consumption as well as reducing emissions. With growing demand for cooling in Turkey, especially during warm seasons and considering the energy costs, utilizing heat-driven absorption cooling systems coupled with an anaerobic digester for local cooling purposes is a potentially interesting alternative for electricity driven compression cooling. The aim of this article is to study the viability of utilizing biogas obtained from MSW anaerobic digestion as the main fuel for heating facilities of Gazi University, Turkey and also the energy source for an absorption cooling system designed for the central library of the aforementioned campus. The results prove that the suggested system is sustainably and financially appealing and has the potential to replace the conventional electricity driven cooling systems with a reasonable net present worth; moreover, it can notably reduce carbon dioxide emissions.

  5. Influence of Internal Heat Generation/Absorption, Thermal Radiation, Magnetic Field, Variable Fluid Property and Viscous Dissipation on Heat Transfer Characteristics of a Maxwell Fluid over a Stretching Sheet

    K.V. Prasad

    2013-01-01

    Full Text Available The present study investigates the effects of internal heat generation/absorption, thermal radiation, magnetic field, and temperature-dependent thermal conductivity on the flow and heat transfer characteristics of a Non-Newtonian Maxwell fluid over a stretching sheet. The upper convected Maxwell fluid model is used to characterize the non-Newtonian fluid behavior. Similarity solutions for the governing equations are obtained with prescribed surface temperature (PST and/or with prescribed surface heat flux (PHF. Numerical solutions for the governing equations subject to the appropriate boundary conditions are obtained by a finite difference scheme known as Keller-Box method. The numerical results thus obtained are analyzed for the effects of the several pertinent parameters namely, the Maxwell parameter, the magnetic parameter, the temperature-dependent thermal conductivity parameter, the heat source/sink parameter, the Prandtl number, the Eckert number, and the thermal radiation parameter on the flow and heat transfer fields. Results for the velocity and temperature fields, skin friction, and Nusselt number are shown through graphs. It is observed that the thermal boundary layer thickness increases with increasing values of the elasticity parameter and the magnetic parameter; however it decreases with the Prandtl number.

  6. Influence of thermal radiation and heat generation/absorption on MHD heat transfer flow of a micropolar fluid past a wedge considering hall and ion slip currents

    Uddin Ziya

    2014-01-01

    Full Text Available In this paper a numerical model is developed to examine the effect of thermal radiation on magnetohydrodynamic heat transfer flow of a micropolar fluid past a non-conducting wedge in presence of heat source/sink. In the model it is assumed that the fluid is viscous, incompressible and electrically conducting. The Hall and ion slip effects have also been taken into consideration. The model contains highly non-linear coupled partial differential equations which have been converted into ordinary differential equation by using the similarity transformations. These equations are then solved numerically by Shooting technique along with the Runge-Kutta-Fehlberg integration scheme for entire range of parameters with appropriate boundary conditions. The effects of various parameters involved in the problem have been studied with the help of graphs. Numerical values of skin friction coefficients and Nusselt number are presented in tabular form. The results showed that the micropolar fluids are better to reduce local skin drag as compared to Newtonian fluids and the presence of heat sink increases the heat transfer rate.

  7. Spectral characterisation and long-term performance analysis of various commercial Heat Transfer Fluids (HTF) as Direct-Absorption Filters for CPV-T beam-splitting applications

    Highlights: • Optical transmittance of 18 different commercial heat transfer fluids has been measured. • Suitable liquids serving as Absorption Filters are Duratherm 600 and G, Propylene Glycol (PG), pink-dyed PG and Royco 782. • Long-term degradation tests include low temperature test at 75 °C, high temperature test at 150 °C, and UV light exposure. • Optimum fluid is the industrial Propylene Glycol adapted with a chemically-inert red dye such as Oil Red 235 inorganic dye. - Abstract: Hybrid concentrated photovoltaic – thermal systems (CPV-T) provide simultaneous supply of electrical and thermal energy, using solar cells with cooling systems to avoid high cell temperatures that decrease the system electrical conversion efficiency. Heat transfer fluids arranged in front of the cell, acting as selective beam-splitting filters, may represent a feasible alternative to absorb unwanted solar radiation, preventing the cell from overheating and directly generating usable thermal output. The cooling efficiency and the temperature output of the liquid depend on optical transmittance as well as chemical and physical stability. A research study for the most suitable commercial heat transfer fluid for a direct-absorption beam-splitting CPV-T system is conducted in this paper, analysing the effects of high temperature and exposure to UV light on the optical transmittance of the fluid under accelerated lifetime test conditions. Optical transmittance of 18 different commercial heat transfer fluids has been measured. The most promising liquids to serve as Direct-Absorption Filters selected for accelerated tests include Duratherm 600, Duratherm G, industrial Propylene Glycol (PG), pink-dyed PG, and Royco 782. Long-term degradation tests include low temperature test at 75 °C, high temperature test at 150 °C, and UV light exposure. Results from the accelerated tests show that the optimum fluid for our application is the industrial grade Propylene Glycol adapted with a

  8. The evaluation of a solar-driven aqua-ammonia diffusion absorption heating and cooling cycle / M.C. Potgieter.

    Potgieter, Marthinus Christiaan

    2013-01-01

    Several steps are followed in order to evaluate the cycle as the title suggests. The diffusion absorption refrigerator (DAR) cycle performance is evaluated when using helium or hydrogen as auxiliary gas. A slight increase in COP is found when using helium, but it is not sufficient to justify the cost. A secondary simulation of an alternate dual-pressure cycle using a pump is done as feasibility comparison with the same parameters as the diffusion cycle. It was found that the second cycle is n...

  9. Applications of the total absorption technique to improve reactor decay heat calculations: study of the beta decay of 102,104,105Tc

    The decay heat of the fission products plays an important role in predicting the heat-up of nuclear fuel after reactor shutdown. This form of energy release is calculated as the sum of the energy-weighted activities of all fission products P(t) = ΣEiλiNi(t), where Ei is the decay energy of nuclide i(gamma and beta component), λi is the decay constant of nuclide i and Ni(t) is the number of nuclide i at cooling time t. Even though the reproduction of the measured decay heat has improved in recent years, there is still a long standing discrepancy at t∼1000 s cooling time for some fuels. A possible explanation for this disagreement can been found in the work of Yoshida et al., who demonstrated that an incomplete knowledge of the β-decay of some Tc isotopes could be the source of the systematic discrepancy. We have recently measured the β-decay process of some Tc isotopes using a total absorption spectrometer at the IGISOL facility in Jyvaeskylae. The results of the measurements are discussed, along with their impact on summation calculations.

  10. Mixed convection stagnation-point flow of nanofluids over a stretching/shrinking sheet in a porous medium with internal heat generation/absorption

    Dulal Pal

    2015-05-01

    Full Text Available In this paper, we analyzed the buoyancy-driven radiative non-isothermal heat transfer in a nanofluid stagnation-point flow over a stretching/shrinking sheet embedded in a porous medium.The effects of thermal radiation and internal heat generation/absorption along with suction/injection at the boundary are also considered. Three different types of nanofluids, namely the Copper-water, the Alumina-water and the Titanium dioxide water are considered. The resulting coupled nonlinear differential equations are solved numerically by a fifth-order Runge-Kutta-Fehlberg integration scheme with a shooting technique. A good agreement is found between the present numerical results and the available results in the literature for some special cases. The effects of the physical parameters on the flow and temperature characteristics are presented through tables and graphs, and the salient features are discussed. The results obtained reveal many interesting behaviors that warrant further study on the heat transfer enhancement due to the nanofluids.

  11. Performance Evaluation of a Lithium-Chloride Absorption Refrigeration and an Assessment of Its Suitability for Biomass Waste Heat

    Sacha Oberweis; Tariq Al-Shemmeri

    2012-01-01

    This paper presents a computer model that will evaluate the performance of a thermo-chemical accumulator. The model is based on operational data such as temperatures and flow rates. The ultimate goal for this model is to estimate the coefficient of performance (COP) of this unit when run on hot water from biomass combustion as the heat source. The outputs of the model are verified by comparing the simulation of the actual machine with published experimental data. The computed results for cool...

  12. Non-Darcy fully developed mixed convection in a porous medium channel with heat generation/absorption and hydromagnetic effects

    Chamkha, A.J. [Kuwait Univ., Safat (Kuwait). Dept. of Mechanical and Industrial Engineering

    1997-11-07

    Volume-averaged equations are developed governing steady, laminar, fully developed, hydromagnetic mixed convection non-Darcian flow of an electrically conducting and heat-generating/absorbing fluid in a channel embedded in a uniform porous medium. Proper dimensionless parameters are employed for various thermal boundary conditions on the left and right walls of the channel prescribed as isothermal-isothermal, isothermal-isoflux, and isoflux-isothermal. Analytical expressions for the velocity and the temperature profiles in the channel as well as for the mass flow rate, friction factor, and heat carried out by the fluid in the channel are developed for special cases of the problem. Conditions for the occurrence of fluid backflow zones are reported. The fully nonlinear governing equations are solved numerically by an implicit finite difference method. Favorable comparisons with the developed analytical results and previously published work are performed. Graphical results of the closed-form and numerical results are reported for various parametric conditions to illustrate special features of the solution. Mixed convection flow of an electrically conducting and heat-generating/absorbing fluid in a porous medium channel in the presence of a magnetic field is of special technical significance because of its frequent occurrence in many industrial applications such as geothermal reservoirs, cooling of nuclear reactors, thermal insulation, and others.

  13. Combined heat and power generation with exhaust-heated two-stage absorption refrigerator. Performance of a pilot installation with a refrigeration capacity of 350 kW; Kraft-Waerme-Kaelte-Kopplung mit Abgas-Beheizter zweistufiger Absorptionskaeltemaschine. Betriebserfahrungen einer Pilotinstallation mit 350 kW Kaelteleistung

    Plura, S.; Baumeister, D.; Koeberle, T.; Radspieler, M.; Schweigler, C. [Bayerisches Zentrum fuer Angewandte Energieforschung e.V. (ZAE Bayern), Garching (Germany)

    2007-07-01

    A new system concept for higher efficiency of cogeneration systems is developed in which a cogeneration unit is combined with a two-stage absorption refrigerator, and the waste heat of the cogeneration unit is directly passed on into the regenerator of the absorption refrigerator. The higher temperature level of the waste heat makes it possible to use a two-stage absorption cycle for higher energy efficiency. For simultaneous utilisation of low-temperature heat, the two-stage cycle is combined with a one-stage cycle for additional heat supply at a lower temperature level so that the exhaust of a typical cogeneration unit will be cooled to about 120 degC. At the same time, further waste heat of the cogeneration unit will be transferred to the heat pump via a hot water circuit. This concept with a combined single-stage and two-stage absorption circuit is referred to as a double-effect/single-effect circuit. The new system is used for energy supply in a spa, where the two-stage absorption refrigerator cools the water used for swimming pool cleaning with a refrigerating capacity of 350 kW and provides low-temperature heat for swimming pool heating with a capacity of 700 kW. (orig.)

  14. Low-cost, heated, and/or cooled flow-through cell for transmission x-ray absorption spectroscopy

    Jentoft, R. E.; Deutsch, S. E.; Gates, B. C.

    1996-06-01

    A transmission x-ray absorption spectroscopy cell that can be used for air-sensitive samples with in situ treatment is described. The cell is designed with a relatively small size for use with air-sensitive powdered catalyst samples that must be loaded in a glove box. Samples can be treated in situ with gas flow or vacuum and temperature control up to 500 °C. The cell is constructed of stainless steel and designed for durability as well as ease of repair. The cells are vacuum tight and equipped with beryllium windows sealed with vacuum O-ring flanges for easy loading. Each cell, with all parts excluding the windows, costs about 2700.

  15. EC emission and absorption in tokamaks: relativistic effects in ray tracing, combined EC-heating and transport codes

    The goal of the paper is to test the fast-routine EC numerical code RAD-Upgrade and the ray-tracing ABSORB-MC code for plasmas in small, average and large tokamaks and to evaluate the possibilities to combine these codes with the transport code ASTRA. This seems to be the first step in the self-consistent treatment of both the EC radiation transport and the global plasma equilibrium and heat transport in tokamak plasmas. The possibilities of the EC codes are demonstrated for various plasma conditions, namely, Russian tokamaks T-10, Tuman-3, T-14, and average size tokamak T-15, with further application to estimations of EC diagnostics possibilities on large tokamaks, including DIII-D and International thermonuclear experimental reactor (ITER)

  16. 双效溴化锂吸收式热泵机组变工况性能模拟%SIMULATION OF OFF-DESIGN PERFORMANCE OF DOUBLE EFFECT LiBr-H2O ABSORPTION HEAT PUMP

    杨筱静; 由世俊; 张欢

    2013-01-01

    According to the thermodynamic and heat-transfer theories, the nonlinear-coupled models of double effect LiBr-H2O absorption heat pump were built to analyze its cooling off-design performance and its heating nominal and off-design performances. These models were solved using interior-reflective Newton method. The simulation results show that the cooling COPC of double effect absorption heat pump with heat-source water flow and solution flow control method is better than that with heat-source water flow control method, but the heat-source water flow is also higher. Moreover, the heating nominal COPh of double effect absorption heat pump is 2.498, better than that of existing absorption water heater chiller. In addition, the off-design performance of absorption heat pump is the best and COPh is 2. 700 when heating load ratio is 40%.%通过对高温热水驱动的双效溴化锂吸收式热泵机组内传热部件进行热力及传热分析,建立非线性耦合模型,并采用内部映射牛顿法进行求解,分析采用高温热源水流量调节法和高温热源水流量与溶液循环量组合式调节法时吸收式热泵机组制冷变工况性能和制热名义工况、制热变工况时热泵机组性能.研究结果表明:泵机组制冷采用高温热源水流量与溶液循环量组合式调节法时COPc较好,但高温热源水流量略高;制热名义工况时机组COP为2.498,制热效果优于现有双效冷温水机组;机组制热变工况性能在负荷率为40%时最优,COPh高达2.700.

  17. Numerical Solutions of Free Convective Flow from a Vertical Cone with Mass Transfer under the Influence of Chemical Reaction and Heat Generation/Absorption in the Presence of UWT/UWC

    Bapuji Pullepu

    2016-01-01

    Full Text Available The purpose of this paper is to present a mathematical model for the combined effects of chemical reaction and heat generation/absorption on unsteady laminar free convective flow with heat and mass transfer over an incompressible viscous fluid past a vertical permeable cone with uniform wall temperature and concentration (UWT/UWC.The dimensionless governing boundary layer equations of the flow that are transient, coupled and non-linear partial differential equations are solved by an efficient, accurate and unconditionally stable finite difference scheme of Crank-Nicholson type. The velocity, temperature, and concentration profiles have been studied for various parameters viz., chemical reaction parameter , the heat generation and absorption parameter  , Schmidt number Sc , Prandtl number Pr , buoyancy ratio parameter N . The local as well as average skin friction, Nusselt number, Sherwood number, are discussed and analyzed graphically. The present results are compared with available results in open literature and are found to be in excellent agreement

  18. Dual stratified mixed convection flow of Eyring-Powell fluid over an inclined stretching cylinder with heat generation/absorption effect

    Rehman, Khalil Ur; Malik, M. Y.; Salahuddin, T.; Naseer, M.

    2016-07-01

    Present work is made to study the effects of double stratified medium on the mixed convection boundary layer flow of Eyring-Powell fluid induced by an inclined stretching cylinder. Flow analysis is conceded in the presence of heat generation/absorption. Temperature and concentration are supposed to be higher than ambient fluid across the surface of cylinder. The arising flow conducting system of partial differential equations is primarily transformed into coupled non-linear ordinary differential equations with the aid of suitable transformations. Numerical solutions of resulting intricate non-linear boundary value problem are computed successfully by utilizing fifth order Runge-Kutta algorithm with shooting technique. The effect logs of physical flow controlling parameters on velocity, temperature and concentration profiles are examined graphically. Further, numerical findings are obtained for two distinct cases namely, zero (plate) and non-zero (cylinder) values of curvature parameter and the behaviour are presented through graphs for skin-friction coefficient, Nusselt number and Sherwood number. The current analysis is validated by developing comparison with previously published work, which sets a benchmark of quality of numerical approach.

  19. X-ray absorption fine structure and field-dependent specific heat measurements of non-Fermi liquid U3Ni3Sn4

    Although most known non-Fermi-liquid (NFL) materials are structurally or chemically disordered, the role of this disorder remains unclear. In particular, very few systems have been discovered that may be stoichiometric and well ordered. To test whether U3Ni3Sn4 belongs in this latter class, we present measurements of the x-ray absorption fine structure of polycrystalline and single-crystal U3Ni3Sn4 samples that are consistent with no measurable local structural disorder. We also present temperature-dependent specific heat data in applied magnetic fields as high as 8 T that show features that are inconsistent with the antiferromagnetic Griffiths' phase model, but do support the conclusion that a Fermi-liquid/NFL crossover temperature increases with applied field. These results are inconsistent with theoretical explanations that require strong disorder effects, but do support the view that U3Ni3Sn4 is a stoichiometric, ordered material that exhibits NFL behavior, and is best described as being near an antiferromagnetic quantum critical point

  20. Fast heating induced impulse halogenation of refractory sample components in electrothermal atomic absorption spectrometry by direct injection of a liquid halogenating agent.

    György, Krisztina; Ajtony, Zsolt; Van Meel, Katleen; Van Grieken, René; Czitrovszky, Aladár; Bencs, László

    2011-09-15

    A novel electrothermal atomic absorption spectrometry (ETAAS) method was developed for the halogenation of refractory sample components (Er, Nd and Nb) of lithium niobate (LiNbO(3)) and bismuth tellurite (Bi(2)TeO(5)) optical single crystals to overcome memory effects and carry-over. For this purpose, the cleaning step of a regular graphite furnace heating program was replaced with a halogenation cycle. In this cycle, after the graphite tube cooled to room temperature, a 20 μL aliquot of liquid carbon tetrachloride (CCl(4)) was dispensed with a conventional autosampler into the graphite tube. The CCl(4) was partially dried at 80°C under the mini-flow (40 cm(3) min(-1)) condition of the Ar internal furnace gas (IFG), then the residue was decomposed (pyrolyzed) by fast furnace heating at 1900-2100°C under interrupted flow of the IFG. This step was followed by a clean-out stage at 2100°C under the maximum flow of the IFG. The advantage of the present method is that it does not require any alteration to the graphite furnace gas supply system in contrast to most of the formerly introduced halogenation techniques. The effectiveness of the halogenation method was verified with the determination of Er and Nd dopants in the optical crystals. In these analyses, a sensitivity decrease was observed, which was likely due to the enhanced deterioration of the graphite tube surface. Therefore, the application of mathematical correction (resloping) of the calibration was also required. The calibration curves were linear up to 1.5 and 10 μmol L(-1) for Er and Nd, respectively. Characteristic masses of 18 and 241 pg and the limit of detection (LOD) values of 0.017 and 0.27 μmol L(-1) were found for Er and Nd, respectively. These LOD data correspond to 0.68 μmol mol(-1) Er and 11 μmol mol(-1) Nd in solid bismuth tellurite samples. The analytical results were compared with those obtained by a conventional ETAAS method and validated with X-ray fluorescence spectrometry analysis

  1. On the sub-band gap optical absorption in heat treated cadmium sulphide thin film deposited on glass by chemical bath deposition technique

    The sub-band gap optical absorption in chemical bath deposited cadmium sulphide thin films annealed at different temperatures has been critically analyzed with special reference to Urbach relation. It has been found that the absorption co-efficient of the material in the sub-band gap region is nearly constant up to a certain critical value of the photon energy. However, as the photon energy exceeds the critical value, the absorption coefficient increases exponentially indicating the dominance of Urbach rule. The absorption coefficients in the constant absorption region and the Urbach region have been found to be sensitive to annealing temperature. A critical examination of the temperature dependence of the absorption coefficient indicates two different kinds of optical transitions to be operative in the sub-band gap region. After a careful analyses of SEM images, energy dispersive x-ray spectra, and the dc current-voltage characteristics, we conclude that the absorption spectra in the sub-band gap domain is possibly associated with optical transition processes involving deep levels and the grain boundary states of the material

  2. Présentation d'une boucle prototype de pompe à chaleur à absorption haute température industrielle de 100 kW Description of a 100-Kw Prototype Loop for an Industrial High-Temperature Absorption Heat-Pump

    Thomas D.

    2006-11-01

    Full Text Available II apparait indispensable, dans le contexte énergétique actuel, de mettre au point de nouvelles techniques de revalorisation d'énergie. Les pompes à chaleur à absorption peuvent, dans certains secteurs industriels, apporter des solutions particulièrement intéressantes par rapport aux pompes à chaleur à compression notamment, en particulier dans le domaine des hautes températures de revalorisation (120-150 °C. Pour mener à bien les études entreprises sur ce thème, le Gaz de France travaille en étroite collaboration avec l'Institut du Génie Chimique de Toulouse et la Société Creusot-Loire. Dans une première partie, les auteurs rappellent les principes de fonctionnement des pompes à chaleurs à absorption et leurs caractères spécifiques. Quelques exemples d'applications industrielles sont proposés. Ils présentent, dans une deuxième partie, la boucle prototype de 100 kW qui a été réalisée et décrivent ses caractéristiques, son cycle de fonctionnement et le programme des essais. Ce pilote de taille semi-industrielle utilise le couple eau-bromure de lithium. La définition d'un prototype industriel de pompe à chaleur à absorption haute température et les compléments de recherche entrepris dans ce domaine constituent la troisième partie de la communication. In the present energy context, it seems absolutely necessary to develop new techniques for energy upgrading. In some industrial sectors, absorption heat pumps may bring particularly interesting solutions compared, in particular, to compression heat pumps, especially in the field of high-temperature upgrading (120-150°C. Reasearch is being done in this field by Gaz de France in close collaboration with the Institut du Génie Chimique in Toulouse and with Creusot-Loire. ,The first part of this article reviews the operating principles of absorption heat pumps and their specific features. Some examples of industrial applications are then proposed. The second part

  3. The design and optimisation of a bubble pump for an aqua-ammonia diffusion absorption heat pump / Stefan van der Walt.

    Van Der Walt, Stefan

    2012-01-01

    Energy shortages around the world necessitated research into alternative energy sources especially for domestic applications to reduce the load on conventional energy sources. This resulted in research done on the possibility of integrating solar energy with an aqua-ammonia diffusion absorption cycle specifically for domestic applications. The bubble pump can be seen as the heart of the diffusion absorption cycle, since it is responsible, in the absence of a mechanical pump, to circulate ...

  4. Solar powered absorption air conditioning

    Vardon, J. M.

    1980-04-01

    Artificial means of providing or removing heat from the building are discussed along with the problem of the appropriate building design and construction for a suitable heat climate inside the building. The use of a lithium bromide-water absorption chiller, powered by a hot water store heated by an array of stationary flat collectors, is analyzed. An iterative method of predicting the cooling output from a LiBr-water absorption refrigeration plant having variable heat input is described and a model allowing investigation of the performance of a solar collector and thermal storage system is developed.

  5. Hot tube atomic absorption spectrochemistry.

    Woodriff, R; Stone, R W

    1968-07-01

    A small, commercially available atomic absorption instrument is used with a heated graphite tube for the atomic absorption analysis of liquid and solid silver samples. Operating conditions of the furnace are described and a sensitivity of about 5 ng of silver is reported. PMID:20068797

  6. Lie Group Analysis for Boundary Layer Flow of Nanofluids near the Stagnation-Point over a Permeable Stretching Surface Embedded in a Porous Medium in the Presence of Radiation and Heat Generation/Absorption

    P. Sreenivasulu

    2015-01-01

    Full Text Available This study investigates the influence of thermal radiation and heat generation/absorption on a two dimensional steady boundary layer flow near the stagnation-point on a permeable stretching sheet in a porous medium saturated with nanofluids. The governing partial differential equations with the appropriate boundary conditions are reduced to a set of ordinary differential equations via Lie-group analysis. The resultant equations are then solved numerically using Runge - Kutta fourth order method along with shooting technique. Two types of nanofluids, namely, copper-water and alumina-water are considered. The velocity and temperature as well as the shear stress and heat transfer rates are computed. The influence of pertinent parameters such as radiation parameter Nr, nanofluid volume fraction parameter , the ratio of free stream velocity and stretching velocity parameter a/c , the permeability parameter K1, suction/blowing parameter S, and heat source/sink parameter  on the flow and heat transfer characteristics is discussed. The present study helps to understand the efficiency of heat transfer transport in nanofluids which are likely to be the smart coolants of the next generation.

  7. Absorption studies

    Absorption studies were once quite popular but hardly anyone does them these days. It is easier to estimate the blood level of the nutrient directly by radioimmunoassay (RIA). However, the information obtained by estimating the blood levels of the nutrients is not the same that can be obtained from the absorption studies. Absorption studies are primarily done to find out whether some of the essential nutrients are absorbed from the gut or not and if they are absorbed, to determine how much is being absorbed. In the advanced countries, these tests were mostly done to detect pernicious anaemia where vitamin B12 is not absorbed because of the lack of the intrinsic factor in the stomach. In the tropical countries, ''malabsorption syndrome'' is quire common. In this condition, several nutrients like fat, folic acid and vitamin B12 are not absorbed. It is possible to study absorption of these nutrients by radioisotopic absorption studies

  8. The Finite Element Method Solution of an Unsteady MHD Free Convection Flow Past an Infinite Vertical Plate with Constant Suction and Heat Absorption

    A Sri Sailam

    2014-04-01

    Full Text Available The study of unsteady hydro magnetic free convective flow of viscous incompressible and electrically conducting fluids past an infinite vertical porous plate in the presence of constant suction and heat absorbing sinks has been made. Appropriate solutions have been derived for the velocity and temperature fields, skin friction and rate of heat transfer using Galerkin finite element method. It is observed that increase in magnetic field strength decreases the velocity of the fluid. Also the skin friction and rate of heat transfer of the conducting fluid decrease with increase in magnetic field strength.

  9. High-efficiency absorption-type heat pumps and refrigerators. From topology to the pilot plant; Hocheffiziente Absorptionsmaschinen zur Versorgung mit Kaelte und Waerme. Von der Topologie zur Pilotanlage

    Ziegler, F.; Demmel, S.; Lamp, P. [Bayerisches Zentrum fuer Angewandte Energieforschung e.V. (ZAE Bayern), Wuerzburg (Germany); Kahn, R. [Technische Univ. Muenchen (Germany). Physik Dept. E19; Alefeld, G.

    1998-12-31

    Absorption-type heat pumps or refrigerators are systems operated with heat. They have been known for a long time and are frequently used especially in airconditioning in the USA and south-east Asia. However, the conventional technique used is subject to many physical limitations, restricting their broader use. The paper demonstrates ways of overcoming these restrictions, for instance by multi-stage design. The exploitation of topological principles much facilitates the synthesis of novel circuits. The technical relevance of such developments is demonstrated by means of selected examples of executed laboratory and pilot plants. Modern absorption technology saves resources and prevents environmental pollution by consuming less fossil energy compared with the conventional technique, for instance by harnessing the thermal potential of solar energy or utilizing waste heat and residual heat, and, not least, thanks to the use of natural refrigerants. (orig.) [Deutsch] Absorptionswaermepumpen oder -kaeltemaschinen sind durch Waerme angetriebene Anlagen, die seit langem bekannt sind und besonders in der Klimatechnik in den USA und im suedostasiatischen Raum haeufig eingesetzt werden. Die dabei verwendete konventionelle Technik unterliegt allerdings vielfaeltigen physikalischen Einschraenkungen, die ihre noch breitere Anwendung verhindern. Es wird gezeigt, wie diese Einschraenkungen beispielsweise durch Mehrstufigkeit ueberwunden werden koennen. Durch die Verwendung topologischer Grundsaetze wird die Synthese neuartiger Kreislaeufe stark vereinfacht. Die technische Bedeutung solcher Entwicklungen wird an ausgewaehlten Beispielen ausgefuehrter Labor- und Pilotanlagen gezeigt. Durch den im Vergleich zu konventioneller Technik geringeren Verbrauch an fossiler Energie, beispielsweise durch die thermische Nutzung von Sonnenenergie oder durch die Nutzung von Ab- oder Restwaerme und nicht zuletzt durch die Verwendung natuerlicher Kaeltemittel werden bei Einsatz moderner

  10. The Finite Element Method Solution of an Unsteady MHD Free Convection Flow Past an Infinite Vertical Plate with Constant Suction and Heat Absorption

    A Sri Sailam

    2014-01-01

    The study of unsteady hydro magnetic free convective flow of viscous incompressible and electrically conducting fluids past an infinite vertical porous plate in the presence of constant suction and heat absorbing sinks has been made. Appropriate solutions have been derived for the velocity and temperature fields, skin friction and rate of heat transfer using Galerkin finite element method. It is observed that increase in magnetic field strength decreases the velocity of the fl...

  11. Potential and limits of sodium hydroxide as an additive to the binary system ammonia/water in absorption heat pumps; Potenzial und Grenzen von Natriumhydroxid als Zusatz zum Stoffpaar Ammoniak/Wasser in Absorptions-Waermepumpen

    Kotenko, Oleksandr; Moser, Harald; Fenzl, Thomas; Rieberer, Rene [Technische Univ. Graz (Austria). Inst. fuer Waermetechnik

    2011-07-01

    Several authors proposed the use of sodium hydroxide (NaOH) as an additive to the ammonia/water working fluid mixture (NH{sub 3} / H{sub 2}O), especially in solar air conditioners. Measured vapour-liquid equilibrium data of this tertiary mixture are found in the relevant literature. Thermodynamic calculations carried out with these data show that the efficiency (COP) will be enhanced in theory while the rectification time will decrease. To verify these theoretical considerations and to gain practical experience with the tertiary mixture NH{sub 3} / H{sub 2}O / NaOH, a test stand was constructed at the Institut fuer Waermetechnik, and measurements were carried out on the mixture NH{sub 3} / H{sub 2}O, i.e. without NaOH, and with 5% NaOH. The technical feasibility of the process was established, although NaOH depositions in the refrigerating circuit caused operational disturbances, so that the mixture had to be renewed regularly and the plant had to be flushed with water. The expected efficiency improvement was not observed. Analyses using ''ASPEN Plus'' showed that this was the result of lower absorber efficiency, which may be due to the higher circulation rate and higher viscosity of the working fluid mixture. Measurements showed a moderate improvements of heat transfer in the expeller after addition of NaOH; no effects were found in the evaporator, solvent heat exchanger and rectification column. The findings suggest that fast implementation of NH{sub 3} / H{sub 2}O / NaOH-AWP is not realistic. Considerable research and development will still be required for optimisation of the absorber for operation with NaOH. [German] Die Verwendung von Natriumhydroxid (NaOH) als Zusatz zum Arbeitsstoffgemisch Ammoniak / Wasser (NH{sub 3} / H{sub 2}O) wurde von verschiedenen Autoren insbesondere fuer das Anwendungsgebiet der solaren Klimatisierung vorgeschlagen. In der einschlaegigen Literatur wurden gemessene Dampf-Fluessig-Gleichgewichts-Daten von diesem

  12. Applicability Analysis on Absorption Ground Source Heat Pump System Assisted by Air Source Heat Pump%空气源热泵辅助吸收式地源热泵系统的适用性分析

    韩宗伟; 王一茹; 阿不来提·依米提; 张艳红; 杨军; 孟欣

    2014-01-01

    针对严寒地区集中供热系统能源利用效率低的问题,结合该地区应用地源热泵系统存在土壤吸/排热不平衡的问题,本文提出将一次网的高温蒸汽(热水)作为吸收式热泵发生器热源的地源热泵系统,利用空气源热泵保障地下换热系统热平衡。介绍了复合系统的运行模式,确定了系统的运行控制策略,选取哈尔滨地区某办公建筑对系统的全年运行性能进行分析。通过计算,系统平均综合性能系数为2.1,相比传统的供暖空调方式节能33.1%。该系统全年运行土壤取/排热不平衡率为3.8%,可以保证土壤温度场以年为周期的热平衡;系统可以长期稳定运行。%In the present study, regarding the low energy efficiency of traditional central heating system in cold regions, and combining with the endothermic/reject heat unbalance of soil for application of ground source heat pump, the ground source heat pump system was proposed by using high temperature steam/water from primary network as the generator heat source and using air source heat pump to ensure the thermal balance of underground heat exchange system. The operation modes of the coupled system were introduced; the control strategy of the system operation was determined and the annual operation performance was analyzed on an office building in Harbin. The results showed that, the system average coefficient of overall performance was calculated to be 2.1, and the energy saving of the proposed system was 33.1%comparing with the traditional central heating way. The soil endothermic/reject heat unbalance rate of the system was 3.8%, which can ensure thermal balance of the soil temperature filed over one year cycle. The long-run effects of the system tended to be stable.

  13. RADIATION ABSORPTION ON AN UNSTEADY CONVECTIVE HEAT AND MASS TRANSFER FLOW PAST A SEMI-INFINITE INCLINED PERMEABLE PLATE EMBEDDED IN A POROUS MEDIUM

    K. Jhansi Rani

    2012-03-01

    Full Text Available Analytical solutions for heat transfer in a laminar flow of a Newtonian viscous electrically conducting and heat generating/ absorbing fluid on an inclined permeable surface has been reported in this paper. The dimensionless governing equations are solved the best possible analytical solution. The influence of various participatingparameters are illustrated graphically and explained in detail. It is noticed that, far away from the bounding surface it is seen that a wide dispersion in the velocity profiles is noticed. Such a phenomena could not be observed in boundary layer region. While the Schmidt number (Sc remains unchanged and as the porosity of the bounding surface decreases, not much of change in the velocity field is noticed. When the bounding is having vertical, as the Schmidt number (Sc increases the velocity is observed to be increasing. Also, as the pore size of the fluid bed decreases the velocity is seen to be increasing. As Schmidt number (Sc decreases the fluid velocity is noticed to be decreasing. The Grashoff number (Gr contributes to the velocity up to some stage and there after a reverse trend is noticed. The modified Grashoff number (Gm appears to influence the velocity field inversely.

  14. Electric field triggering the spin reorientation and controlling the absorption and release of heat in the induced multiferroic compound EuTiO3

    von Ranke, P. J.; Gama, S.; Ribeiro, P. O.; Carvalho, A. Magnus G.; Alho, B. P.; Alvarenga, T. S. T.; Nobrega, E. P.; Caldas, A.; de Sousa, V. S. R.; Lopes, P. H. O.; de Oliveira, N. A.

    2015-12-01

    We report remarkable results due to the coupling between the magnetization and the electric field induced polarization in EuTiO3. Using a microscopic model Hamiltonian to describe the three coupled sublattices, Eu-(spin-up), Eu-(spin-down), and Ti-(moment), the spin flop and spin reorientation phase transitions were described with and without the electric-magnetic coupling interaction. The external electric field can be used to tune the temperature of the spin reorientation phase transition TSR = TSR(E). When the TSR is tuned around the EuTiO3—Néel temperature (TN = 5.5 K), an outstanding effect emerges in which EuTiO3 releases heat under magnetic field change. The electric field controlling the spin reorientation transition and the endo-exothermic processes are discussed through the microscopic interactions model parameters.

  15. Electric field triggering the spin reorientation and controlling the absorption and release of heat in the induced multiferroic compound EuTiO3

    We report remarkable results due to the coupling between the magnetization and the electric field induced polarization in EuTiO3. Using a microscopic model Hamiltonian to describe the three coupled sublattices, Eu-(spin-up), Eu-(spin-down), and Ti-(moment), the spin flop and spin reorientation phase transitions were described with and without the electric-magnetic coupling interaction. The external electric field can be used to tune the temperature of the spin reorientation phase transition TSR = TSR(E). When the TSR is tuned around the EuTiO3—Néel temperature (TN = 5.5 K), an outstanding effect emerges in which EuTiO3 releases heat under magnetic field change. The electric field controlling the spin reorientation transition and the endo-exothermic processes are discussed through the microscopic interactions model parameters

  16. Similarity Analysis for Effects of Variable Diffusivity and Heat Generation/Absorption on Heat and Mass Transfer for a MHD Stagnation-Point Flow of a Convective Viscoelastic Fluid over a Stretching Sheet with a Slip Velocity

    H. M. El-Hawary

    2013-01-01

    Full Text Available A mathematical analysis has been carried out for stagnation-point heat and mass transfer of a viscoelastic fluid over a stretching sheet with surface slip velocity, concentration dependent diffusivity, thermal convective boundary conditions, and heat source/sink. The governing partial differential equations are reduced to a system of nonlinear ordinary differential equations using Lie group analysis. Numerical solutions of the resulting ordinary differential equations are obtained using shooting method. The influences of various parameters on velocity, temperature, and mass profiles have been studied. Also, the effects of various parameters on the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are given in graphics form and discussed.

  17. Electric field triggering the spin reorientation and controlling the absorption and release of heat in the induced multiferroic compound EuTiO{sub 3}

    Ranke, P. J. von, E-mail: von.ranke@uol.com.br; Ribeiro, P. O.; Alho, B. P.; Alvarenga, T. S. T.; Nobrega, E. P.; Caldas, A.; Sousa, V. S. R. de; Lopes, P. H. O.; Oliveira, N. A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro–UERJ, Rua São, Francisco Xavier, 524, 20550-013 Rio de Janeiro, Rio de Janerio (Brazil); Gama, S. [Departamento de Ciências Exatas e da Terra-UNIFESP, Diadema, 09971-270 Sao Paulo (Brazil); Carvalho, A. Magnus G. [Laboratório Nacional de Luz Síncrotron, CNPEM, 13083-970 Campinas, Sao Paulo (Brazil)

    2015-12-28

    We report remarkable results due to the coupling between the magnetization and the electric field induced polarization in EuTiO{sub 3}. Using a microscopic model Hamiltonian to describe the three coupled sublattices, Eu-(spin-up), Eu-(spin-down), and Ti-(moment), the spin flop and spin reorientation phase transitions were described with and without the electric-magnetic coupling interaction. The external electric field can be used to tune the temperature of the spin reorientation phase transition T{sub SR} = T{sub SR}(E). When the T{sub SR} is tuned around the EuTiO{sub 3}—Néel temperature (T{sub N} = 5.5 K), an outstanding effect emerges in which EuTiO{sub 3} releases heat under magnetic field change. The electric field controlling the spin reorientation transition and the endo-exothermic processes are discussed through the microscopic interactions model parameters.

  18. Ultrafast THz Saturable Absorption in Doped Semiconductors

    Turchinovich, Dmitry; Hoffmann, Matthias C.

    2011-01-01

    We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields.......We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields....

  19. Seasonal Solar Thermal Absorption Energy Storage Development.

    Daguenet-Frick, Xavier; Gantenbein, Paul; Rommel, Mathias; Fumey, Benjamin; Weber, Robert; Gooneseker, Kanishka; Williamson, Tommy

    2015-01-01

    This article describes a thermochemical seasonal storage with emphasis on the development of a reaction zone for an absorption/desorption unit. The heat and mass exchanges are modelled and the design of a suitable reaction zone is explained. A tube bundle concept is retained for the heat and mass exchangers and the units are manufactured and commissioned. Furthermore, experimental results of both absorption and desorption processes are presented and the exchanged power is compared to the results of the simulations. PMID:26842331

  20. Ultrafast THz Saturable Absorption in Semiconductors

    Turchinovich, Dmitry; Hoffmann, Matthias C.

    2011-01-01

    We demonstrate THz saturable absorption in n-doped semiconductors GaAs, GaP, and Ge in a nonlinear THz time-domain spectroscopy experiment. Saturable absorption is caused by sample conductivity modulation due to electron heating and satellite valley scattering in the field of a strong THz pulse....

  1. Conceptual design of an advanced absorption cycle: the double-effect regenerative absorption refrigeration cycle

    Dao, K.

    1978-09-01

    An advanced absorption refrigeration cycle was proposed as a heat-activated refrigeration system. Referred to as the double-effect regenerative absorption cycle of cycle 2R, it improves the performance of the conventional single-effect absorption cycle at high heat source temperatures. The performance of cycle 2R continually improves as input temperatures rise, in contrast to the conventional double-effect absorption cycle that has a sharp cut-off temperature below which it ceases to operate. Cycle 2R operates with two subcycles, the first-effect and the second-effect subcycles.

  2. A cylindrical furnace for absorption spectral studies

    R Venkatasubramanian

    2001-06-01

    A cylindrical furnace with three heating zones, capable of providing a temperature of 1100°C, has been fabricated to enable recording of absorption spectra of high temperature species. The temperature of the furnace can be controlled to ± 1°C of the set temperature. The salient feature of this furnace is that the material being heated can be prevented from depositing on the windows of the absorption cell by maintaining a higher temperature at both the ends of the absorption cell.

  3. An analysis of the investment risk related to the integration of a supercritical coal-fired combined heat and power plant with an absorption installation for CO2 separation

    Highlights: • Two variants of a CHP plant – with and without integration with CCS were analyzed. • For the CHP plant main investment risk factors were identified. • For two variants risk analyses based on Monte Carlo method have been carried out. • For evaluation of the investment risk four indices were defined and calculated. - Abstract: For two variants of a supercritical coal-fired combined heat and power plant a thermodynamic, economic and risk analyses were carried out. The first variant consists of a unit working without realization of CO2 capture process. The second one is the unit integrated with a chemical absorption CO2 capture installation. In this variant the heat required for the desorption process is supplied with steam extracted from the steam turbine. The developed model of the CHP plant allowed to obtain main operation characteristics for annual change of load. For the two analyzed variants the characteristics of the amount of produced electricity (gross and net), generated heat and consumed chemical energy of fuel, as a function of the cogeneration unit operation time per year, were determined. In the next stage of calculations these characteristics were required to carry out the economic and risk analysis. Economic performances were evaluated in terms of the break-even price of electricity. The performed analysis proves that both investment projects will achieve the same economic effect, i.e. 85.26 €/MW h, if the price of emissions allowances reaches the value of 47.88 €/MgCO2. In this case, the potentially better variant of the system may be indicated based on the result of the risk analysis. In order to perform the risk analysis the main technical and economic risk factors concerning implementation of this technology were identified. The risk analysis was conducted with the use of Monte Carlo method. Based on the determined cumulative probability curves of obtaining specified values of the break-even price of electricity, it was

  4. 泡沫陶瓷太阳能吸收、转换与传递特性研究%THE CHARACTERISTIC RESEARCH OF SOLAR ABSORPTIVITY, ENERGYCONVERSION AND HEAT TRANSFER IN FOAM CERAMICS

    邓洋波; 王玉龙; 苏风民; 严春吉

    2012-01-01

    通过实验测试和数值模拟对太阳辐射能量转换器(solar energy converter)及其填充的泡沫陶瓷辐射吸收特性、气流流动和换热特性进行研究.研究结果表明:应用Lacoix模型建立太阳辐射能量转换器内填充SiC泡沫陶瓷气流流动模型是合理的.在实验条件下,太阳辐射能量转换器出口处流通空气温度可达600.82K,太阳辐射辐射能转换为流通空气热能的效率可达51%;在相同条件下,随着太阳能反射镜的有效辐射面积和辐射强度的增加,太阳辐射能量转换器出口处流通空气温度几乎呈线性增长;随着泡沫陶瓷孔隙率增大,太阳辐射能量转换器出口处流通空气温度先增大后减小.%In this paper, numerical simulation and experience were carried out to study the solar radiation absorp-tance, the conversion efficiency of the solar energy, the characteristics of the flow and heat transfer, for the solar energy converter filled with SiC foam ceramics. The results showed that the solid frame structure of the ceramic foams absorbs solar radiation, convert it into thermal energy, and heat the air flow through the ceramic foams by convection heat transfer. It is reasonable to set up the flow model in SiC ceramic foam by Lacoix' s flow model in porous media. Under experimental condition, the temperature at the outlet of the solar energy converter arrives at 600.82K, and conversion efficiency of the solar energy arrives at 51 %. Under same condition, the air temperature at the outlet of the solar energy converter increases, with the effective reflective area and the solar radiation intensity of the solar converter. The air temperature at the outlet of the solar energy converter increases with increasing the porosity of the ceramic foams at begining.

  5. 太阳能热变换器制蒸汽系统性能研究%Performances of a Steam Generation System With a Solar Assisted Absorption Heat Transformer

    刘锋; 隋军; 刘浩; 金红光

    2015-01-01

    构建了一套蒸汽产量为1 t/h(制热功率为620 kW)的太阳能辅助吸收式热变换器(solar assisted absorption heat transformer,SAAHT)制蒸汽系统,探讨了太阳辐照强度、环境温度以及蒸汽凝水回收率对制热量和系统热效率的影响。结果表明,当太阳辐照强度由200 W/m2增加到1000W/m2时,系统热效率提高20.4个百分点,制热功率增加1090 kW;当环境温度由15℃升高到33℃时,系统热效率先由26.6%缓慢增大至27.8%,然后快速下降至9.27%,制热功率先由593.6kW 增大至619.5 kW ,然后下降至206.6kW。当蒸汽凝水由不回收变化到全回收,系统热效率提高2.75个百分点,制热功率增加61kW。研究提出不同太阳辐照强度、环境温度以及凝水回收率条件下系统最佳集热温度。经济性分析结果表明,该系统产汽成本为162元/t,其替代燃油锅炉和燃气锅炉时,投资回收期介于1.95年和6.70年之间,与燃煤锅炉相比,没有明显的价格优势,但CO2减排量突出。%ABSTRACT:A solar assisted absorption heat transformer (SAAHT) system generating 1 t /h low pressure steam was developed and the influence of solar radiation intensity, ambient temperature and condensate water recovery ratio of low pressure steam on the system thermal efficiency and heat load used by the steam user were studied. When solar radiation intensity ranges from 200W/m2 to 1000W/m2, the system thermal efficiency increases by 20.4 percentage points and heat load for steam user increases 1090 kW. When ambient temperature ranges from 15℃ to 33℃, the system thermal efficiency increases from 26.6% to 27.8%, and then decreases to 9.27%; heat load for steam user increases from 593.6kW to 619.5kW and then decreases to 206.6kW. When condensate water recovery ratio ranges from 0 to 1, the system thermal efficiency increases by 2.75 percentage points and heat load for steam user increases 61kW. Considering the variation

  6. Broadband absorption engineering of hyperbolic metafilm patterns

    Ji, Dengxin; Song, Haomin; Zeng, Xie; Hu, Haifeng; Liu, Kai; Zhang, Nan; Gan, Qiaoqiang

    2014-01-01

    Perfect absorbers are important optical/thermal components required by a variety of applications, including photon/thermal-harvesting, thermal energy recycling, and vacuum heat liberation. While there is great interest in achieving highly absorptive materials exhibiting large broadband absorption using optically thick, micro-structured materials, it is still challenging to realize ultra-compact subwavelength absorber for on-chip optical/thermal energy applications. Here we report the experime...

  7. Optical absorption in irradiated natural beryl

    Three species of beryl irradiated with γ-rays of 60Co were studied by optical absorption. One became yellow and the other two Maxixe's blue. The effects of heat treatments were determined by the thermal isochronal decays of the optical absorption bands. Activation energies and frequency factor were obtained through the first order process kinetic model. Discussions lend us to assign for the UV band-edge the model of absorption by a hole center stabilized by a Fe2+ (substituting Al3+) ion in a neighbour oxygen. (Author)

  8. Fishnet metamaterials with incorporated titanium absorption layer

    Some metamaterial applications require the use of high-power lasers, but the incoming radiation may damage the metamaterials. In addition to that, the presence of an absorptive material placed close to metamaterial surface can lead to quick heating of the surrounding area, resulting in serious thermal damage or melting of the fabricated pattern. We study the impact of a titanium absorptive layer on top of a conventional fishnet structure and we show that due to increased absorption the melting power is reduced by nearly 50% and thermal damage leads to the formation of microbumps on the exposed surface. (paper)

  9. D-xylose absorption

    ... this page: //medlineplus.gov/ency/article/003606.htm D-xylose absorption To use the sharing features on this page, please enable JavaScript. D-xylose absorption is a laboratory test to determine ...

  10. D-xylose absorption

    D-xylose absorption is a laboratory test to determine how well the intestines absorb a simple sugar (D-xylose). The test ... test is primarily used to determine if nutrient absorption problems are due to a disease of the ...

  11. Evolution of absorption machines; Evolution des machines a absorption

    Soide, I.; Klemsdal, E. [Gaz de France (GDF), 75 - Paris (France); Le Goff, P.; Hornut, J.M. [LSGC-ENSIC, 54 - Nancy (France)

    1997-12-31

    Most of todays absorption air-conditioning machineries use the lithium bromide-water pair. The most performing can operate at a 150-160 deg. C, the temperature being limited by the corrosion resistance of metals with respect to LiBr solutions. Also, there is a revival of interest for water-ammonia systems. These systems require the use of a rectification column which reduces the coefficient of performance. Higher thermal performances are reached with hydrocarbon pairs and ternary mixtures (water-methanol-LiBr etc..). This paper presents different schemes of refrigerating heat pumps based on these different systems. (J.S.)

  12. Nutrition and magnesium absorption.

    Brink, E.J.

    1992-01-01

    The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true magnesium absorption was neither affected by soybean protein in the diet nor by supplemental phytate. The inhibitory influence of soybean protein and phytate on apparent magnesium absorption was found to be cau...

  13. Modelación de la transferencia de calor y masa en el absorbedor de una máquina de refrigeración por absorción. // Heat and mass transference modeling in the absorvetor of an absorption cooling device.

    C. Cisneros Ramírez

    2003-01-01

    Full Text Available En este artículo se dan las expresiones que caracterizan el comportamiento de la temperatura y del producto coeficienteglobal de traspaso de calor (U por el área de traspaso de calor (A , de un absorbedor de una máquina de refrigeración porabsorción que trabaja con la solución amoniaco – agua.Palabras claves: Modelación, absorbedores, refrigeración por absorción.______________________________________________________________________________Abstract.In this article the expressions that characterize the temperature performance and the global heat exchange (U by the heatexchange area (A of the absorvetor of an absorption refrigerating equipment with aqua–ammonia solution are given.Key words: Model, absorber, absorption refrigeration.

  14. Absorption of some powder materials to YAG laser

    SHAOT.M.; LINX.C.; ZHOUM.

    2001-01-01

    Laser powder alloying is widely used for tribological applications. As one of the key pa-rameters , absorptivity of powder materials to laser plays an important role in the processing. Themeasurement of laser absorptivity is essential for absorptivity research. In present work, lumpedmethod based on heat transfer is established for laser absorptivity measurement. The absorptivityof some powder materials as Cu, Fe, Al, NiO, Al2O3, ZrO2, SiC, to YAG laser, are investigated.The results show that the absorptivity of powder materials to YAG laser is generally larger thanthat of bulk materials.

  15. Alfven wave heating

    The physics of Alfven-wave heating is particularly sensitive to the character of the linear mode conversion which occurs at the Alfven resonance layer. Parameter changes can profoundly affect both the location within the plasma and the mechanism for the power absorption. Under optimal conditions the heating power may be absorbed by electron Landau damping and by electron transit-time magnetic pumping in the plasma interior, or by the same processes acting near the resonance layer on the mode-converted kinetic Alfven wave. The method is outlined for computing the coefficients for reflection, transmission and absorption at the resonance layer and some representative results are offered

  16. Calcium absorption and achlorhydria

    Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

  17. ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Local Control of Two-Photon Absorption in a Six-Level Atomic System by Using a Coherent Perturbation Field

    Jia, Wen-Zhi; Wang, Shun-Jin

    2009-11-01

    If a coherent perturbation field is used to couple the excited level of the coupling transition in the five-level K-type atom with another higher excited level, the two-photon electromagnetically induced transparency can be locally modulated by altering the parameters of the additional perturbation field. With different detunings of the coherent perturbation field, the absorption peak or transparency window with sharp and high-contrast spectral feature can be generated in the two-photon absorption spectrum. The physical interpretation of these phenomena is given in terms of the dressed states.

  18. Absorptive coating for aluminum solar panels

    Desmet, D.; Jason, A.; Parr, A.

    1979-01-01

    Method for coating forming coating of copper oxide from copper component of sheet aluminum/copper alloy provides strong durable solar heat collector panels. Copper oxide coating has solar absorption characteristics similar to black chrome and is much simpler and less costly to produce.

  19. Variability of calcium absorption

    Variability in calcium absorption was estimated in three groups of normal subjects in whom Ca absorption was measured by standard isotopic-tracer methods at interstudy intervals ranging from 1 to 4 mo. Fifty absorption tests were performed in 22 subjects. Each was done in the morning after an overnight fast with an identical standard breakfast containing a Ca load of approximately 250 mg. Individual fractional absorption values were normalized to permit pooling of the data. The coefficient of variation (CVs) for absorption for the three groups ranged from 10.57 to 12.79% with the size of the CV increasing with interstudy duration. One other published study presenting replicate absorption values was analyzed in a similar fashion and was found to have a CV of absorption of 9.78%. From these data we estimate that when the standard double-isotope method is used to measure Ca absorption there is approximately 10% variability around any given absorption value within an individual human subject and that roughly two-thirds of this represents real biological variability in absorption

  20. Fluid absorption solar energy receiver

    Bair, Edward J.

    1993-01-01

    A conventional solar dynamic system transmits solar energy to the flowing fluid of a thermodynamic cycle through structures which contain the gas and thermal energy storage material. Such a heat transfer mechanism dictates that the structure operate at a higher temperature than the fluid. This investigation reports on a fluid absorption receiver where only a part of the solar energy is transmitted to the structure. The other part is absorbed directly by the fluid. By proportioning these two heat transfer paths the energy to the structure can preheat the fluid, while the energy absorbed directly by the fluid raises the fluid to its final working temperature. The surface temperatures need not exceed the output temperature of the fluid. This makes the output temperature of the gas the maximum temperature in the system. The gas can have local maximum temperatures higher than the output working temperature. However local high temperatures are quickly equilibrated, and since the gas does not emit radiation, local high temperatures do not result in a radiative heat loss. Thermal radiation, thermal conductivity, and heat exchange with the gas all help equilibrate the surface temperature.

  1. Review on absorption technology with emphasis on small capacity absorption machines

    Labus Jerko M.

    2013-01-01

    Full Text Available The aim of this paper is to review the past achievements in the field of absorption systems, their potential and possible directions for future development. Various types of absorption systems and research on working fluids are discussed in detail. Among various applications, solar cooling and combined cooling, heating and power (CCHP are identified as two most promising applications for further development of absorption machines. Under the same framework, special attention is given to the small capacity absorption machines and their current status at the market. Although this technology looks promising, it is still in development and many issues are open. With respect to that fact, this paper covers all the relevant aspects for further development of small capacity absorption machines.

  2. Investigation of ejector re-compression absorption refrigeration cycle

    Wu, Shenyi

    1999-01-01

    This thesis describes a theoretical and experimental investigation of the ejector re-compression lithium bromide absorption refrigeration cycle. In this novel cycle, a steam ejector is used to enhance the concentration process by compressing the vapour to a state that it can be used to re-heat the solution from where it was evolved. Since this cycle recovers the heat otherwise wasted in a conventional absorption cycle, the energy performance of the cycle is improved. The theoretical study sho...

  3. Wave and plasma heating

    In the field of wave heating absorption studies of plasma magnetic waves in the theta pinch are extended to axially inhomogeneous waves. In the Plasmaus 4 experiment direct plasma production has been accomplished for overcritical densities and high magnetic fields. The numerical methods developed at IPF for plasma simulation studies have been applied successfully to further problems. (orig./GG)

  4. Nutrition and magnesium absorption.

    Brink, E.J.

    1992-01-01

    The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true magnesium abs

  5. Zeeman atomic absorption spectroscopy

    A new method of background correction in atomic absorption spectroscopy has recently been introduced, based on the Zeeman splitting of spectral lines in a magnetic field. A theoretical analysis of the background correction capability observed in such instruments is presented. A Zeeman atomic absorption spectrometer utilizing a 50 Hz sine wave modulated magnetic field is described. (Auth.)

  6. Petawatt laser absorption bounded

    Levy, Matthew C; Tabak, Max; Libby, Stephen B; Baring, Matthew G

    2014-01-01

    The interaction of petawatt ($10^{15}\\ \\mathrm{W}$) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light $f$, and even the range of $f$ is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that $f$ exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials.

  7. Aerosol light absorption and its measurement: A review

    Light absorption by aerosols contributes to solar radiative forcing through absorption of solar radiation and heating of the absorbing aerosol layer. Besides the direct radiative effect, the heating can evaporate clouds and change the atmospheric dynamics. Aerosol light absorption in the atmosphere is dominated by black carbon (BC) with additional, significant contributions from the still poorly understood brown carbon and from mineral dust. Sources of these absorbing aerosols include biomass burning and other combustion processes and dust entrainment. For particles much smaller than the wavelength of incident light, absorption is proportional to the particle volume and mass. Absorption can be calculated with Mie theory for spherical particles and with more complicated numerical methods for other particle shapes. The quantitative measurement of aerosol light absorption is still a challenge. Simple, commonly used filter measurements are prone to measurement artifacts due to particle concentration and modification of particle and filter morphology upon particle deposition, optical interaction of deposited particles and filter medium, and poor angular integration of light scattered by deposited particles. In situ methods measure particle absorption with the particles in their natural suspended state and therefore are not prone to effects related to particle deposition and concentration on filters. Photoacoustic and refractive index-based measurements rely on the heating of particles during light absorption, which, for power-modulated light sources, causes an acoustic signal and modulation of the refractive index in the air surrounding the particles that can be quantified with a microphone and an interferometer, respectively. These methods may suffer from some interference due to light-induced particle evaporation. Laser-induced incandescence also monitors particle heating upon absorption, but heats absorbing particles to much higher temperatures to quantify BC mass

  8. Quasar Absorption Studies

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  9. Percutaneous absorption in diseased skin: an overview.

    Chiang, Audris; Tudela, Emilie; Maibach, Howard I

    2012-08-01

    The stratum corneum's (SC) functions include protection from external hazardous environments, prevention of water loss and regulation of body temperature. While intact skin absorption studies are abundant, studies on compromised skin permeability are less common, although products are often used to treat affected skin. We reviewed literature on percutaneous absorption through abnormal skin models. Tape stripping is used to disrupt water barrier function. Studies demonstrated that physicochemical properties influence the stripping effect: water-soluble drugs are more affected. Abrasion did not affect absorption as much. Freezing is commonly used to preserve skin. It does not seem to modify water absorption, but still increases the penetration of compounds. Comparatively, heating the skin consistently increased percutaneous absorption. Removing SC lipids may increase percutaneous absorption of drugs. Many organic solvents are employed to delipidize. Delipidization with chloroform-methanol increased hydrophilic compound permeability, but not lipophilic. Acetone pre-treatment enhanced hydrophilic compound penetration. More data is needed to determine influence on highly lipophilic compound penetration. Sodium lauryl sulfate (SLS) induces irritant dermatitis and is frequently used as a model. Studies revealed that SLS increases hydrophilic compound absorption, but not lipophilic. However, skin irritation with other chemicals increases lipophilic penetration as much as hydrophilic. Animal studies show that UV exposure increases percutaneous absorption whereas human studies do not. Human studies show increased penetration in psoriatic and atopic dermatitis skin. The data summarized here begin to characterize flux alteration associated with damaged skin. Understanding the degree of alteration requires interpretation of involved conditions and the enlarging of our database to a more complete physicochemical spectrum. PMID:22912973

  10. Quantum-enhanced absorption refrigerators.

    Correa, Luis A; Palao, José P; Alonso, Daniel; Adesso, Gerardo

    2014-01-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators. PMID:24492860