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02393 A review of developments in solid-vapour adsorption-refrigeration and heat-pump systems
15
Environment
(pollution, health protection,
safety)
TIM-PCM external wall system for solar space heating and dayllghtlng
98102307
Manz, H. et al. Solar Energy, 1997, 61, (6), 369-379. The authors introduce an external wall system for solar space heating and daylighting composed of transparent insulation material (TIM) and translucent phase change material (PCM). Selective optical transmittance of solar radiation is possible with this system. Visible light is mainly transmitted and invisible radiation is mainly absorbed and converted to heat, causing in particular phase change. In this system, the storage medium is also the absorber. The concept detailed together with the investigations carried out, including a brief outline of modelling, optical experiments on PCM samples and long-term experiments on a prototype wall as well as numerical simulations. The results indicate a promising thermal-optical behaviour of the system. Results are given. With regard to the practical application of the system in buildings, it is necessary to investigate aspects of reliability and durability further.
pump is taken as the optimization objective function. Using the method of finite-time exergoeconomic analysis, this paper derives the relation between optimal profit and coefficient of performance (COP) of an endoreversible Carnot heat pump based on a relatively general heat transfer law: qmA(7”). The COP bound at the maximum profit is also obtained. 98102392 Optimization of steady flow heat pumps Wu, C. el al. Energy Cowers. Mgmt, 1998, 39, (S/6), 445-453. For both finite and infinite thermal capacitance rates of heat reservoirs, the finite-time thermodynamic performance of steady flow Carnot and Brayton heat pump cycles has been studied. The fundamental optimal relations of the two cycles are obtained. The performance characteristics of the two cycles for the same boundary conditions are compared. The effects of finite thermal capacitance rates of the working fluid and heat reservoirs and of the internal irreversibilities of the cycles on cycle performance are analysed. Optimal matching between the temperatures of the working fluid and heat reservoirs is discussed.
A review of developments in solivapour refrigeration and heat-pump systems
gal02393
14 HEAT PUMPS Analysis of chemical heat pumps (CHPS): basic concepts and numerical model description
9alO2308
Mbaye, M. et al. Appl. Therm. Eng., 1998 (Pub. 1997), 18, (3-4), 131-146. During the reaction between a gas and solid porous media, thermochemical phenomena were modelled. The authors envisage the use of these thermochemical materials in chemical heat pumps (CHP). In the synthesis part of the cycle, a gas at a moderate pressure reacts uniformly with the salt component of a thermochemical material. The ammoniated salt is subsequently decomposed to release the gas at an elevated pressure. A detailed numerical model is presented for the decomposition phase of the CHP reaction cycle. The numerical simulation of a CHP reactor during a synthesis-decomposition reaction cycle has several specific requirements. The phase change problem involving discontinuities in the thermal properties of the two different salts at their reaction interface needs special care for numerical solution. The source-based method which is a fixed grid enthalpy approach, was used in this paper. Using a control volume approach around each spatial node, the solution of the partial differential equation was obtained. This thermal study examined configurations with different reactor diameters and other parameters that influenced heat transfer. Typical results included conversions, power generated as a function of reactor diameter and time-onstream, required heat exchange area and heat losses.
Design of low temperature absorption heat pump which uses water as working fluid and water solution of LiBr as absorbent
98iO2389
Langfelder, I. et al. Pet. Coal, 1996, 38, (4), 35-39. The paper presents the engineering calculation of a heat pump permitting the recovery of low potential waste heat produced in considerable quantities in industry, transport, agriculture or public utilities. Apart from energy losses, it represents considerable environmental ballast. The proposed system uses water as working fluid and water solution of LiBr as absorbent. The engineering calculation aims for the determination of the efficiency of the equipment, defined by the ratio of the produced energy on a required temperature level to the energy supplied to the equipment. In essence, five heat exchangers comprise the apparatus, which is both extremely safe and reliable. It provides useful heat, at the required temperature level, more than 1.7 times the input energy.
Effect of climatic conditions on the design optimization of heat pump systems for space heating and cooling
adsorption-
Srivastava, N. C. and Eames, 1. W. .I. Inst. Enew, December 1997, 70, 116-127. There have been considerable efforts over the past 10 years to use solidvapour adsorption technology for refrigeration, but intensified efforts were initiated only since the imposition of international restrictions on the production and use of chlorofluorocarbons. Yet, to this date only the desiccant evaporative cooling system of the open type has achieved commercial use, predominantly in the USA. Closed-type solid-vapour refrigeration and heat-pump systems are still at the laboratory testing stage. Promising recent developments in Japan, Europe and the USA include the use of porous metal hydrides and composite adsorbents. Various analytical investigations relate to devising methods for improving system performance, such as the use of thermal wave concept. They predict considerable improvement in the performance of solid-vapour adsorption systems with cooling COP values of more than unity. This paper presents the status of solid-vapour adsorption-refrigeration and heat-pump technologies investigated by various researchers, with emphasis on salient experimental achievements.
Techno-economic analysis between the performances of heat source air conditioners in South Africa
98102394
Petit, P. J. and Meyer, J. P. Energy Convers. Mgmr, 1998, 39, (7), 661-669. A comparison of alternative heat pump systems for use in South African climatic conditions is undertaken in this paper. Monthly heating/cooling capacities and coefficients of performance for air-source and vertical and horizontal ground-source systems have been calculated. The desired type of heat exchanger is determined by considering economic factors and the costeffectiveness of investments of each system is calculated. The authors conclude that the horizontal ground-source heat exchanger is the most economically viable.
15 ENVIRONMENT Pollution, Health Protection,
Safety
98lo2390
Zogou, 0. and Stamatelos, A. Energy Convers. &ml, 1998, 39, (7), 609622. A substantial percentage of world energy is consumed by domestic heating and cooling. The most energy efficient heating and cooling provision is offered by heat pumps in many applications, as they can use renewable heat sources of the building’s surroundings. A number of related heat pump technology versions exist that have led to significantly lower heating and cooling energy consumption in certain climatic conditions. A comparative discussion about the effect of climatic conditions on applying ground source heat pump technologies is provided. It is shown that the attainable building energy consumption reduction with ground source heat pump systems may be significantly higher in the warmer Mediterranean climatic conditions. To this end, advanced technology residential heat pump systems should be employed and their operation matched to the specific climatic conditions. It is concluded that climatic conditions significantly affect the performance of heat pump systems. It is recommended that if an optimization is sought on sustainability grounds, this should lead to markedly different strategies for domestic heating and cooling. gal02391 Effect of heat transfer law on finite-time exergoeconomic performance of Carnot heat pump Wu, C. et al. Energy Cowers. Mgml, 1998, 39, (7), 579-588. A Carnot heat pump’s operation is viewed as a production process with exergy as its output. The paper performs the short-run economic optimization of the endoreversible heat pump and the profit of the heat
216
Fuel and Energy Abstracts
May 1998
Activated carbon membrane for water treatments: application to decolorlzation of coke furnace wastewater
gal02395
Sakoda, A. et al. Adsorption, 1997, 3, (l), 93-98. The development of an activated carbon membrane for water treatments is cited and the decolourization of the coke furnace wastewater was demonstrated. The activated carbon membrane was prepared by carbonizing poly(vinylidenechloride) and poly(vinylalcohol) microspheres aggregating on and within a ceramic pipe. This membrane was suspected to have a bidispersed structure, which made it possible to play the roles of both a porous membrane having the molecular weight cut-off of -10 000 and an activated carbon bed where the dissolved organics with low molecular weight could be adsorbed. This activated carbon membrane is useful for compact water treatment processes.
Adsorption and denltrificatlon characteristics activated coke for advanced flue gas treatment
98lO2396
of
Kawamoto, K. et al. Haikibutsu Gakkai Ronbunshu, 1997, 8, (6), 241-250. Municipal solid waste incinerator flue gas was treated with activated coke developed as a material to adsorb NO, and SO,. This material is a denitrification catalyst which can simultaneously adsorb trace organic compounds. The treatability of some types of airborne pollutants was studied. Activated coke adsorption capacity for 1,2-dichloro-benzene at ppm concentrations was -l/10 of that by activated carbon. This capacity decreased by -40% with a 30°C increase in temperature above 120°C. Furthermore, an increase in gas moisture decreased adsorption. The extent
Environment
(pollution, health protection,
safety)
TIM-PCM external wall system for solar space heating and dayllghtlng
98102307
Manz, H. et al. Solar Energy, 1997, 61, (6), 369-379. The authors introduce an external wall system for solar space heating and daylighting composed of transparent insulation material (TIM) and translucent phase change material (PCM). Selective optical transmittance of solar radiation is possible with this system. Visible light is mainly transmitted and invisible radiation is mainly absorbed and converted to heat, causing in particular phase change. In this system, the storage medium is also the absorber. The concept detailed together with the investigations carried out, including a brief outline of modelling, optical experiments on PCM samples and long-term experiments on a prototype wall as well as numerical simulations. The results indicate a promising thermal-optical behaviour of the system. Results are given. With regard to the practical application of the system in buildings, it is necessary to investigate aspects of reliability and durability further.
pump is taken as the optimization objective function. Using the method of finite-time exergoeconomic analysis, this paper derives the relation between optimal profit and coefficient of performance (COP) of an endoreversible Carnot heat pump based on a relatively general heat transfer law: qmA(7”). The COP bound at the maximum profit is also obtained. 98102392 Optimization of steady flow heat pumps Wu, C. el al. Energy Cowers. Mgmt, 1998, 39, (S/6), 445-453. For both finite and infinite thermal capacitance rates of heat reservoirs, the finite-time thermodynamic performance of steady flow Carnot and Brayton heat pump cycles has been studied. The fundamental optimal relations of the two cycles are obtained. The performance characteristics of the two cycles for the same boundary conditions are compared. The effects of finite thermal capacitance rates of the working fluid and heat reservoirs and of the internal irreversibilities of the cycles on cycle performance are analysed. Optimal matching between the temperatures of the working fluid and heat reservoirs is discussed.
A review of developments in solivapour refrigeration and heat-pump systems
gal02393
14 HEAT PUMPS Analysis of chemical heat pumps (CHPS): basic concepts and numerical model description
9alO2308
Mbaye, M. et al. Appl. Therm. Eng., 1998 (Pub. 1997), 18, (3-4), 131-146. During the reaction between a gas and solid porous media, thermochemical phenomena were modelled. The authors envisage the use of these thermochemical materials in chemical heat pumps (CHP). In the synthesis part of the cycle, a gas at a moderate pressure reacts uniformly with the salt component of a thermochemical material. The ammoniated salt is subsequently decomposed to release the gas at an elevated pressure. A detailed numerical model is presented for the decomposition phase of the CHP reaction cycle. The numerical simulation of a CHP reactor during a synthesis-decomposition reaction cycle has several specific requirements. The phase change problem involving discontinuities in the thermal properties of the two different salts at their reaction interface needs special care for numerical solution. The source-based method which is a fixed grid enthalpy approach, was used in this paper. Using a control volume approach around each spatial node, the solution of the partial differential equation was obtained. This thermal study examined configurations with different reactor diameters and other parameters that influenced heat transfer. Typical results included conversions, power generated as a function of reactor diameter and time-onstream, required heat exchange area and heat losses.
Design of low temperature absorption heat pump which uses water as working fluid and water solution of LiBr as absorbent
98iO2389
Langfelder, I. et al. Pet. Coal, 1996, 38, (4), 35-39. The paper presents the engineering calculation of a heat pump permitting the recovery of low potential waste heat produced in considerable quantities in industry, transport, agriculture or public utilities. Apart from energy losses, it represents considerable environmental ballast. The proposed system uses water as working fluid and water solution of LiBr as absorbent. The engineering calculation aims for the determination of the efficiency of the equipment, defined by the ratio of the produced energy on a required temperature level to the energy supplied to the equipment. In essence, five heat exchangers comprise the apparatus, which is both extremely safe and reliable. It provides useful heat, at the required temperature level, more than 1.7 times the input energy.
Effect of climatic conditions on the design optimization of heat pump systems for space heating and cooling
adsorption-
Srivastava, N. C. and Eames, 1. W. .I. Inst. Enew, December 1997, 70, 116-127. There have been considerable efforts over the past 10 years to use solidvapour adsorption technology for refrigeration, but intensified efforts were initiated only since the imposition of international restrictions on the production and use of chlorofluorocarbons. Yet, to this date only the desiccant evaporative cooling system of the open type has achieved commercial use, predominantly in the USA. Closed-type solid-vapour refrigeration and heat-pump systems are still at the laboratory testing stage. Promising recent developments in Japan, Europe and the USA include the use of porous metal hydrides and composite adsorbents. Various analytical investigations relate to devising methods for improving system performance, such as the use of thermal wave concept. They predict considerable improvement in the performance of solid-vapour adsorption systems with cooling COP values of more than unity. This paper presents the status of solid-vapour adsorption-refrigeration and heat-pump technologies investigated by various researchers, with emphasis on salient experimental achievements.
Techno-economic analysis between the performances of heat source air conditioners in South Africa
98102394
Petit, P. J. and Meyer, J. P. Energy Convers. Mgmr, 1998, 39, (7), 661-669. A comparison of alternative heat pump systems for use in South African climatic conditions is undertaken in this paper. Monthly heating/cooling capacities and coefficients of performance for air-source and vertical and horizontal ground-source systems have been calculated. The desired type of heat exchanger is determined by considering economic factors and the costeffectiveness of investments of each system is calculated. The authors conclude that the horizontal ground-source heat exchanger is the most economically viable.
15 ENVIRONMENT Pollution, Health Protection,
Safety
98lo2390
Zogou, 0. and Stamatelos, A. Energy Convers. &ml, 1998, 39, (7), 609622. A substantial percentage of world energy is consumed by domestic heating and cooling. The most energy efficient heating and cooling provision is offered by heat pumps in many applications, as they can use renewable heat sources of the building’s surroundings. A number of related heat pump technology versions exist that have led to significantly lower heating and cooling energy consumption in certain climatic conditions. A comparative discussion about the effect of climatic conditions on applying ground source heat pump technologies is provided. It is shown that the attainable building energy consumption reduction with ground source heat pump systems may be significantly higher in the warmer Mediterranean climatic conditions. To this end, advanced technology residential heat pump systems should be employed and their operation matched to the specific climatic conditions. It is concluded that climatic conditions significantly affect the performance of heat pump systems. It is recommended that if an optimization is sought on sustainability grounds, this should lead to markedly different strategies for domestic heating and cooling. gal02391 Effect of heat transfer law on finite-time exergoeconomic performance of Carnot heat pump Wu, C. et al. Energy Cowers. Mgml, 1998, 39, (7), 579-588. A Carnot heat pump’s operation is viewed as a production process with exergy as its output. The paper performs the short-run economic optimization of the endoreversible heat pump and the profit of the heat
216
Fuel and Energy Abstracts
May 1998
Activated carbon membrane for water treatments: application to decolorlzation of coke furnace wastewater
gal02395
Sakoda, A. et al. Adsorption, 1997, 3, (l), 93-98. The development of an activated carbon membrane for water treatments is cited and the decolourization of the coke furnace wastewater was demonstrated. The activated carbon membrane was prepared by carbonizing poly(vinylidenechloride) and poly(vinylalcohol) microspheres aggregating on and within a ceramic pipe. This membrane was suspected to have a bidispersed structure, which made it possible to play the roles of both a porous membrane having the molecular weight cut-off of -10 000 and an activated carbon bed where the dissolved organics with low molecular weight could be adsorbed. This activated carbon membrane is useful for compact water treatment processes.
Adsorption and denltrificatlon characteristics activated coke for advanced flue gas treatment
98lO2396
of
Kawamoto, K. et al. Haikibutsu Gakkai Ronbunshu, 1997, 8, (6), 241-250. Municipal solid waste incinerator flue gas was treated with activated coke developed as a material to adsorb NO, and SO,. This material is a denitrification catalyst which can simultaneously adsorb trace organic compounds. The treatability of some types of airborne pollutants was studied. Activated coke adsorption capacity for 1,2-dichloro-benzene at ppm concentrations was -l/10 of that by activated carbon. This capacity decreased by -40% with a 30°C increase in temperature above 120°C. Furthermore, an increase in gas moisture decreased adsorption. The extent