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Performance analysis of a vapor compression heat pump using zeotropic refrigerant mixtures
14 Heat pumps indicated by the measurement and evaluation of six mandates, namely thermal, spatial, visual, acoustic, indoor air quality, and building integrity. The usage of both objective and subjective methods gave rise to interesting and sometimes conflicting results with regards to the classrooms’ performance.
Both the first law and the second law were used to analyse the heat pump operation. The state parameters and the process quantities were evaluated by using, as input, the building thermal load. The second law analysis emphasized that most of the exergy losses occur during compression and condensation. Preliminary results show that the photovoltaic array can provide all the energy required to drive the heat pump compressor, if an appropriate electrical energy storage system is provided.
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03/00865 Performance analysis of a vapor compression heat pump using zeotropic refrigerant mixtures Yilmaz, M. Energ), Conversion and Management, 2003, 44, (2), 267-282. This paper presents the performance analysis of an air-to-water vapour compression heat pump system using pure refrigerants and zeotropic refrigerant mixtures. The heat pump system is composed of a compressor, condenser, air cooled evaporator, expansion valve, a receiver tank, a superheater/subcooler, refrigerant mixture unit and some auxiliary and measurement devices. The study focuses on the second law efficiency characteristics of the heat pump system. Comparisons are made between the pure refrigerants and refrigerant mixtures on the basis of the COP and second law efficiency. Also, the effect of the evaporator source inlet temperature on the COP and second law efficiency is presented. It was found that the mixture ratio affects the COP and second law efficiency significantly, and the COP and second law efficiency for the pure refrigerants could be improved by using an appropriate mixture of the refrigerants.
HEAT PUMPS
03/00861 Convective heat transport along a thermoacoustic couple in the transient regime Piccolo, A. and Cannistraro, G. International Journal qf Thermal Sciences, 2003, 41, (11), 1067-1075. This work proposes a simple calculus procedure based on the linear thermoacoustic theory. The methodology applies on rate of change (time derivative) rather than on steady state temperature distributions so it constitutes a complementary to conventional analysis to perform test on the reliability and applicability of the linear theory. The procedure has been applied to experimental data collected by means of a simple prototype of thermoacoustic device. The apparatus, whose technical characteristics are described in detail along with the data acquisition procedure, has been able to highlight the general features of the thermoacoustic effect. Measurements concern the acoustically generated temperature gradients across a ThermoAcoustic Couple, a structure first introduced by Wheatley and coworkers in 1983. The obtained results indicate that heat transfer phenomena are more critical than non-linear acoustic behaviour in determining the overestimation that theoretical predictions make on experimental values. Exergy analysis and experimental study of heat 03/00862 pump systems Bilgen, E. and Takahashi, H. Exergy, An International Journal, 2002, 2, (4), 259-265. Exergy analysis of heat pump-air conditioner systems has been carried out. The irreversibilities due to heat transfer and friction have been considered. The coefficient of performance based on the first law of thermodynamics as a function of various parameters, their optimum values, and the efficiency and coefficient of performance based on exergy analysis have been derived. Based on the exergy analysis, a simulation program has been developed to simulate and evaluate experimental systems. The simulation of a domestic heat pump-air conditioner of 959 W nominal power (Matsushita room air conditioner model CS-XG28M) is then carried out using experimental data. It is found that COP based on the first law varies from 7.40 to 3.85 and the exergy efficiency from 0.37 to 0.25 both a decreasing function of heating or cooling load. The exergy destructions in various components are determined for further study and improvement of its performance. 03/00863 Experimental study on the kinetics of water vapor sorption on selective water sorbents, silica gel and alumina under typical operating conditions of sorption heat pumps Dawoud, B. and Aristov, Y. International Journal of Heat and Muss Transfbr, 2003, 46, (2), 273-281. A selective water sorbent (SWS) is a composite material consisting of a porous host matrix and a hygroscopic substance (commonly an inorganic salt) impregnated into its pores. This work presents an experimental investigation for the kinetics of water vapour sorption on two host materials; namely mesoporous silica gel and alumina in comparison with the two composites SWS-1L and SWS-1A formed by impregnating these two host matrices with CaC12. Moreover, the kinetics of water vapour sorption on microporous silica gel have been also investigated. The measurements have been carried out on 3 g samples of loose pellets on an isothermal wall under three different operating conditions of sorption heat pumps. The results obtained evidence a remarkable increase in the differential water loading of both SWS-sorbents over their host materials. However, and due to the increased diffusion resistance to water sorption resulting from the salt impregnation, the kinetics of water sorption into the host matrices is faster than that into the two SWS-composites. Moreover, SWS-1L is found to be faster than SWS-1A in- sorbing water vapour. The differential water loading on microporous silica is about twice that on mesoporous silica and alumina, but the sorption kinetics are a little bit slower. 03/00864 First and second law analysis of a solar assisted heat pump based heating system Badescu, V. Energy Conversion and Management, 2002, 43, (18), 25392552. A model is proposed for the heating system of an ecological building whose main energy source is solar radiation. The most important component of the heating system is a vapour compression heat pump. 178
Fuel and Energy Abstracts
May 2003
03/00866 Theoretical and basic experimental analysis on load adjustment of geothermal heat pump systems Zhao, L. et al. Energy Conversion and Management, 2003, 44, (l), l-9. In order to match the output capacity of a geothermal heat pump system (GHPS) with the actual load requirement, research has been conducted in searching for suitable adjusting methods for the GHPS and on the subsequent effects on the working parameters of the GHPS. Firstly, several methods are compared, and it is found that the method of adjusting the compressor’s rotation speed using a transducer is better than the others. Secondly, this method is experimented on a small scale GHPS at frequencies ranging from 30 to 55 Hz. The analysis of the experimental data reveals the relationships between the compressor frequency and other important parameters, such as coefficient of performance, heat capacity, cool capacity and compressor power input. The conclusions in the paper can serve as some guidance to the load adjustment of GHPS.
03/00867 Thermodynamic study of multistage absorption cycles using low-temperature heat Venegas, M. et al. International Journal of Energy Research, 2002, 26, (8), 775-79 1. The use of low-temperature heat (50-90”) is studied to drive absorption systems in- two different applications: refrigeration and heat pump cycles. Double- and triple-stage absorption systems are modeled and simulated, allowing a comparison between the absorbentrefrigerant solutions H20-NHs, LiN03-NH3 and NaSCN-NHs. The results obtained for the double-stage cycle show that in the refrigeration cycle the LiNOs-NH3 solution operates with a COP of 0.32, the HzO-NH3 pairs with a COP of 0.29 and the NaSCN-NH3 solution with a COP of 0.27, when it evaporates at -15”. Condenses and absorbs refrigerant at 40” and generates vapour at 90”. The results are presented for double- and triple-stage absorption systems with evapouration temperatures ranging between -40 and 0” and condensation temperatures ranging from 15-45”. The results obtained for the double-stage heat pump cycle show that the LiNOs-NH3 solution reaches a COP of 1.32, the NaSCN-NH3 pair a COP of 1.30 and the H20-NH? mixture a COP of 1.24, when it condenses and absorbs refrigerant at 50”, evaporates at 0” and generates vapour at 90”. For the double- and triple-stage cycles, the results are presented for evaporation temperatures ranging between O-15”. The minimum temperature required in the generators to operate the refrigeration and heat pump cycles are also presented.
03/00868 Thermoeconomic optimization for irreversible absorption refrigerators and heat pumps Kodal, A. et al. Energy Conversion and Management, 2003, 44, (I), 109123. A performance analysis using finite time thermodynamics based on a thermoeconomic objective function has been performed for absorption irreversible refrigerators and heat pumps. The optimal design parameters at the maxima of the thermoeconomic objective functions for an absorption refrigerator and heat pump have been derived analytically, and the effects of the internal irreversibility, the economical parameter and the external temperatures on the global and optimal performances have been discussed.
Both the first law and the second law were used to analyse the heat pump operation. The state parameters and the process quantities were evaluated by using, as input, the building thermal load. The second law analysis emphasized that most of the exergy losses occur during compression and condensation. Preliminary results show that the photovoltaic array can provide all the energy required to drive the heat pump compressor, if an appropriate electrical energy storage system is provided.
14
03/00865 Performance analysis of a vapor compression heat pump using zeotropic refrigerant mixtures Yilmaz, M. Energ), Conversion and Management, 2003, 44, (2), 267-282. This paper presents the performance analysis of an air-to-water vapour compression heat pump system using pure refrigerants and zeotropic refrigerant mixtures. The heat pump system is composed of a compressor, condenser, air cooled evaporator, expansion valve, a receiver tank, a superheater/subcooler, refrigerant mixture unit and some auxiliary and measurement devices. The study focuses on the second law efficiency characteristics of the heat pump system. Comparisons are made between the pure refrigerants and refrigerant mixtures on the basis of the COP and second law efficiency. Also, the effect of the evaporator source inlet temperature on the COP and second law efficiency is presented. It was found that the mixture ratio affects the COP and second law efficiency significantly, and the COP and second law efficiency for the pure refrigerants could be improved by using an appropriate mixture of the refrigerants.
HEAT PUMPS
03/00861 Convective heat transport along a thermoacoustic couple in the transient regime Piccolo, A. and Cannistraro, G. International Journal qf Thermal Sciences, 2003, 41, (11), 1067-1075. This work proposes a simple calculus procedure based on the linear thermoacoustic theory. The methodology applies on rate of change (time derivative) rather than on steady state temperature distributions so it constitutes a complementary to conventional analysis to perform test on the reliability and applicability of the linear theory. The procedure has been applied to experimental data collected by means of a simple prototype of thermoacoustic device. The apparatus, whose technical characteristics are described in detail along with the data acquisition procedure, has been able to highlight the general features of the thermoacoustic effect. Measurements concern the acoustically generated temperature gradients across a ThermoAcoustic Couple, a structure first introduced by Wheatley and coworkers in 1983. The obtained results indicate that heat transfer phenomena are more critical than non-linear acoustic behaviour in determining the overestimation that theoretical predictions make on experimental values. Exergy analysis and experimental study of heat 03/00862 pump systems Bilgen, E. and Takahashi, H. Exergy, An International Journal, 2002, 2, (4), 259-265. Exergy analysis of heat pump-air conditioner systems has been carried out. The irreversibilities due to heat transfer and friction have been considered. The coefficient of performance based on the first law of thermodynamics as a function of various parameters, their optimum values, and the efficiency and coefficient of performance based on exergy analysis have been derived. Based on the exergy analysis, a simulation program has been developed to simulate and evaluate experimental systems. The simulation of a domestic heat pump-air conditioner of 959 W nominal power (Matsushita room air conditioner model CS-XG28M) is then carried out using experimental data. It is found that COP based on the first law varies from 7.40 to 3.85 and the exergy efficiency from 0.37 to 0.25 both a decreasing function of heating or cooling load. The exergy destructions in various components are determined for further study and improvement of its performance. 03/00863 Experimental study on the kinetics of water vapor sorption on selective water sorbents, silica gel and alumina under typical operating conditions of sorption heat pumps Dawoud, B. and Aristov, Y. International Journal of Heat and Muss Transfbr, 2003, 46, (2), 273-281. A selective water sorbent (SWS) is a composite material consisting of a porous host matrix and a hygroscopic substance (commonly an inorganic salt) impregnated into its pores. This work presents an experimental investigation for the kinetics of water vapour sorption on two host materials; namely mesoporous silica gel and alumina in comparison with the two composites SWS-1L and SWS-1A formed by impregnating these two host matrices with CaC12. Moreover, the kinetics of water vapour sorption on microporous silica gel have been also investigated. The measurements have been carried out on 3 g samples of loose pellets on an isothermal wall under three different operating conditions of sorption heat pumps. The results obtained evidence a remarkable increase in the differential water loading of both SWS-sorbents over their host materials. However, and due to the increased diffusion resistance to water sorption resulting from the salt impregnation, the kinetics of water sorption into the host matrices is faster than that into the two SWS-composites. Moreover, SWS-1L is found to be faster than SWS-1A in- sorbing water vapour. The differential water loading on microporous silica is about twice that on mesoporous silica and alumina, but the sorption kinetics are a little bit slower. 03/00864 First and second law analysis of a solar assisted heat pump based heating system Badescu, V. Energy Conversion and Management, 2002, 43, (18), 25392552. A model is proposed for the heating system of an ecological building whose main energy source is solar radiation. The most important component of the heating system is a vapour compression heat pump. 178
Fuel and Energy Abstracts
May 2003
03/00866 Theoretical and basic experimental analysis on load adjustment of geothermal heat pump systems Zhao, L. et al. Energy Conversion and Management, 2003, 44, (l), l-9. In order to match the output capacity of a geothermal heat pump system (GHPS) with the actual load requirement, research has been conducted in searching for suitable adjusting methods for the GHPS and on the subsequent effects on the working parameters of the GHPS. Firstly, several methods are compared, and it is found that the method of adjusting the compressor’s rotation speed using a transducer is better than the others. Secondly, this method is experimented on a small scale GHPS at frequencies ranging from 30 to 55 Hz. The analysis of the experimental data reveals the relationships between the compressor frequency and other important parameters, such as coefficient of performance, heat capacity, cool capacity and compressor power input. The conclusions in the paper can serve as some guidance to the load adjustment of GHPS.
03/00867 Thermodynamic study of multistage absorption cycles using low-temperature heat Venegas, M. et al. International Journal of Energy Research, 2002, 26, (8), 775-79 1. The use of low-temperature heat (50-90”) is studied to drive absorption systems in- two different applications: refrigeration and heat pump cycles. Double- and triple-stage absorption systems are modeled and simulated, allowing a comparison between the absorbentrefrigerant solutions H20-NHs, LiN03-NH3 and NaSCN-NHs. The results obtained for the double-stage cycle show that in the refrigeration cycle the LiNOs-NH3 solution operates with a COP of 0.32, the HzO-NH3 pairs with a COP of 0.29 and the NaSCN-NH3 solution with a COP of 0.27, when it evaporates at -15”. Condenses and absorbs refrigerant at 40” and generates vapour at 90”. The results are presented for double- and triple-stage absorption systems with evapouration temperatures ranging between -40 and 0” and condensation temperatures ranging from 15-45”. The results obtained for the double-stage heat pump cycle show that the LiNOs-NH3 solution reaches a COP of 1.32, the NaSCN-NH3 pair a COP of 1.30 and the H20-NH? mixture a COP of 1.24, when it condenses and absorbs refrigerant at 50”, evaporates at 0” and generates vapour at 90”. For the double- and triple-stage cycles, the results are presented for evaporation temperatures ranging between O-15”. The minimum temperature required in the generators to operate the refrigeration and heat pump cycles are also presented.
03/00868 Thermoeconomic optimization for irreversible absorption refrigerators and heat pumps Kodal, A. et al. Energy Conversion and Management, 2003, 44, (I), 109123. A performance analysis using finite time thermodynamics based on a thermoeconomic objective function has been performed for absorption irreversible refrigerators and heat pumps. The optimal design parameters at the maxima of the thermoeconomic objective functions for an absorption refrigerator and heat pump have been derived analytically, and the effects of the internal irreversibility, the economical parameter and the external temperatures on the global and optimal performances have been discussed.