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In this study, a direct expansion solar-assisted heat pump water heater (DX-SAHPWH) with rated input power 750 W was tested and analyzed. Through experimental research in spring and thermodynamics analysis about the system performance, some suggestions for the system optimization are proposed. Then, a small-type DX-SAHPWH with rated input power 400 W was built, tested and analyzed. Through exergy analysis for each component of DX-SAHPWH (A) and (B), it can be seen that the highest exergy loss occurs in the compressor and collector/evaporator, followed by the condenser and expansion valve, respectively. Furthermore, some methods are suggested to improve the performance of each component, especially the collector/evaporator. A methodology for the design optimization of the collector/evaporator was introduced and applied. In order to maintain a proper matching between the heat pumping capacity of the compressor and the evaporative capacity of the collector/evaporator under widely varying ambient conditions, the electronic expansion valve and variable frequency compressor are suggested to be utilized for the DX-SAHPWH. 相似文献
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S.K. Chaturvedi T.M. Abdel-Salam S.S. Sreedharan F.B. Gorozabel 《Applied Thermal Engineering》2009,29(10):2093-2099
Direct expansion solar-assisted heat pump (DX-SAHP) systems have been proposed as viable alternatives to conventional solar-assisted heat pump systems. This study proposes the use of two-stage DX-SAHP systems for high temperature applications in the range of 60–90 °C. The study investigates the capability of these systems of meeting loads with high temperature requirements. The thermal performance of the systems is analyzed for refrigerant R-134a, using a one-cover solar collector. Comparisons between the two-stage DX-SAHP and the single-stage DX-SAHP systems are performed and presented. A graphical procedure is illustrated and used for sizing the solar collector area and the heat pump compressor displacement capacity for the two DX-SAHP systems. 相似文献
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Thermal performance analysis of a direct-expansion solar-assisted heat pump water heater 总被引:1,自引:0,他引:1
A direct-expansion solar-assisted heat pump water heater (DX-SAHPWH) is described, which can supply hot water for domestic use during the whole year. The system mainly employs a bare flat-plate collector/evaporator with a surface area of 4.2 m2, an electrical rotary-type hermetic compressor, a hot water tank with the volume of 150 L and a thermostatic expansion valve. R-22 is used as working fluid in the system. A simulation model based on lumped and distributed parameter approach is developed to predict the thermal performance of the system. Given the structure parameters, meteorological parameters, time step and final water temperature, the numerical model can output operational parameters, such as heat capacity, system COP and collector efficiency. Comparisons between the simulation results and the experimental measurements show that the model is able to give satisfactory predictions. The effect of various parameters, including solar radiation, ambient temperature, wind speed and compressor speed, has been analyzed on the thermal performance of the system. 相似文献
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Long-term performance of solar-assisted heat pump water heater 总被引:1,自引:0,他引:1
A long-term reliability test of an integral-type solar-assisted heat pump water heater (ISAHP) was carried out. The prototype has been running continuously for more than 13,000 h with total running time >20,000 h during the past 5 yr. The measured energy consumption is 0.019 kWh/l of hot water at 57 oC that is much less than the backup electric energy consumption of the conventional solar water heater. 相似文献
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《Exergy》2001,1(2):107-111
The thermodynamic optimization of a mechanically driven solar heat pump is presented. A new expression to describe the optimal thermal performance under finite operating conditions considering the internal and external irreversibilities during actual operation is derived. The optimum ratio between the condenser and collector–evaporator conductances (UA) determines the coefficient of performance (COP) for the maximum heating load of the system. An experimental air-R22 heat pump was used to determine the traditional performance parameters (COP and second law efficiency) which are compared with those obtained using the expressions derived in this work. Results show that the new model very closely represents the performance of real systems. 相似文献
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Thermal performance parameters for a solar-assisted heat pump (SAHP) drying system with underground thermal energy storage (TES) tank and heat recovery unit (HRU) are investigated in this study. The SAHP drying system is made up of a drying unit, a heat pump, flat plate solar collectors, an underground TES tank, and HRU. An analytical model is developed to obtain the performance parameters of the drying system by using the solution of heat transfer problem around the TES tank and energy expressions for other components of the drying system. These parameters are coefficient of performances for the heat pump (COP) and system (COPs), specific moisture evaporation rate (SMER), temperature of water in the TES tank, and energy fractions for energy charging and extraction from the system. A MATLAB program has been prepared using the expressions for the drying system. The obtained results for COP, COPs, and SMER are 5.55, 5.28, and 9.25, respectively, by using wheat mass flow rate of 100 kg h−1, Carnot efficiency of 40%, collector area of 100 m2, and TES tank volume of 300 m3 when the system attains periodic operation duration in fifth year onwards for 10 years of operation. Annual energy saving is 21.4% in comparison with the same system without using HRU for the same input data. 相似文献
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The performance of photovoltaic/thermal (PV/T) solar collector had been studied theoretically and experimentally for some years. Air and water streams were used as the heat carriers for space heating or services hot water systems. The cooling effect allows the PV module to work at lower temperature and its PV efficiency is therefore improved. However, such an advantage diminishes when the solar irradiance is high. To improve the situation a new type of PV/T collector is proposed. It works as the evaporator of a heat pump, in that refrigerant evaporates in the tubing at the back of the flat-plate collector and the PV module is adhered to the front surface. Mathematical models were developed to simulate the complex energy conversion processes. Numerical analysis was then performed based on the distributed parameters approach. An experimental rig was also built to test its real performance. Our results showed that the PV/T evaporator had an overall efficiency in the range of 0.64–0.87, thermal efficiency 0.53–0.64 and PV efficiency 0.124–0.135. The simulation results were found in good agreement with the experiment measurements. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Experimental performance analysis on a direct-expansion solar-assisted heat pump water heater 总被引:3,自引:0,他引:3
A direct expansion solar assisted heat pump water heater (DX-SAHPWH) experimental set-up is introduced and analyzed. This DX-SAHPWH system mainly consists of 4.20 m2 direct expansion type collector/evaporator, R-22 rotary-type hermetic compressor with rated input power 0.75 kW, 150 L water tank with immersed 60 m serpentine copper coil and external balance type thermostatic expansion valve. The experimental research under typical spring climate in Shanghai showed that the COP of the DX-SAHPWH system can reach 6.61 when the average temperature of 150 L water is heated from 13.4 °C to 50.5 °C in 94 min with average ambient temperature 20.6 °C and average solar radiation intensity 955 W/m2. And the COP of the DX-SAHPWH system is 3.11 even if at a rainy night with average ambient temperature 17.1 °C. The seasonal average value of the COP and the collector efficiency was measured as 5.25 and 1.08, respectively. Through exergy analysis for each component of the DX-SAHPWH system, it can be calculated that the highest exergy loss occurs in the compressor, followed by collector/evaporator, condenser and expansion valve, respectively. Further more, some methods are suggested to improve the thermal performance of each component and the whole DX-SAHPWH system. 相似文献
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A novel indirect expansion solar-assisted multi-functional heat pump (IX-SAMHP) system which composes of the multi-functional heat pump system and solar thermal collecting system is proposed and studied in this paper. This system can fulfill space heating, space cooling and water heating with high energy efficiency by utilizing solar energy. For solar water heating mode and solar space heating mode, a dynamic model is presented and validated with the experimental results. The simulation results show good consistency with the experimental data, and the established model is able to predict the system performance at a reasonable accuracy (with the root mean square deviations less than 5%). On this basis, the performances of the IX-SAMHP system are investigated under different parametric conditions. For solar water heating mode, simultaneously operating the solar thermal collecting system and multi-functional heat pump system can be an energy efficiency method. With the solar irradiation rising from 0W/m2 to 800W/m2, the COP increases from 2.35 to 2.57. In solar space heating mode, the effect of the mass flow rate of water in evaporator is investigated. To balance the heating capacity and COP, the mass flow rate of water should be adjusted according to different temperature demands and heat load. 相似文献
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Integral-type solar-assisted heat pump water heater 总被引:2,自引:0,他引:2
An integral-type solar-assisted heat pump water heater (ISAHP) is designed and tested in the present study. The storage tank and the Rankine cycle unit are integrated together to make a more compact size. A thermosyphon loop is used to transfer the heat from the condenser to the water storage tank. The highest COP obtained in the tests is 3.83. 相似文献
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Minduan Tu 《国际能源研究杂志》1987,11(4):559-572
A solar-assisted heat-pump system is proposed to supply heat for industrial processes in the range 100 to 130°C. The system is economically superior to electrical heating and solar-only systems, and is competitive with fuel burning systems. 相似文献
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《Energy》1998,23(4):337-344
A theoretical and experimental exergy analysis of a solar-assisted heat pump for air heating is presented. An experimental prototype that operates as a solar-assisted or as a conventional heat pump was tested to determine exergetic efficiency, total system irreversibility and component irreversibilities. A methodology for determination of the optimum temperature of the working fluid in the evaporation and condensation steps is proposed. The methodology is based on maximization of efficiency in these two parts of the system. 相似文献
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Performance analysis of a solar-assisted heat pump water heater 总被引:2,自引:0,他引:2
A modeling and system simulation of an integral-type solar assisted heat pump water heater (ISAHP) was carried out in the present study. The modeling and simulation assumes a quasi-steady process for all the components in the ISAHP except the storage tank. The simulation results for instantaneous performance agreed very well with experiment. The simulation technique was used to analyze the daily performance of an ISAHP for 1 year. It is shown that the daily total COP (COPo) is around 1.7 to 2.5 year around for the ISAHP, depending on seasons and weather conditions. COPo is higher than 2.0 for most of the time in a year and the daily operating time varies from 4 to 8 h. The online adjustment requirement of the expansion valve was also investigated using the present simulation technique. The analysis shows that the expansion device does not need to be controlled online. Using the 1-year simulation results, a universal daily performance correlation of the ISAHP was derived and shown experimentally to be applicable to another design of ISAHP. 相似文献
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The simulation of performance of seasonal heat storage coupled to solar-assisted heat pump in Jordan
Mohammed Awwad Ali Al-Dabbas 《Applied Solar Energy》2009,45(2):83-92
In this paper the performance of seasonal heat storage coupled to solar-assisted heat pump in the Jordan region was investigated. The system has been studied by means of a model in which the thermal budget of each component has been described by simplified differential equation. A parametric analysis has provided the yearly energy saving by varying the building heat requirement, the area of collectors, the heat storage size, and insulation for different area. As a result, a number of diagrams are proposed, which can be used for preliminary evaluation of the efficiency of these kinds of systems. 相似文献
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Heat-pipe enhanced solar-assisted heat pump water heater 总被引:4,自引:0,他引:4
A heat-pipe enhanced solar-assisted heat pump water heater (HPSAHP) is studied. HPSAHP is a heat pump with dual heat sources that combines the performance of conventional heat pump and solar heat pipe collector. HPSAHP operates in heat-pump mode when solar radiation is low and in heat-pipe mode without electricity consumption when solar radiation is high. HPSAHP can thus achieve high energy efficiency. A prototype was designed and built in the present study. An outdoor test for a HPSAHP in the present study has shown that COP of the hybrid-mode operation can reach 3.32, an increase of 28.7% as compared to the heat-pump mode COP (2.58). 相似文献
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The characteristic of an integral type solar-assisted heat pump water heater (ISAHP) is investigated in the present study. The ISAHP consists of a Rankine refrigeration cycle and a thermosyphon loop that are integrated together to form a package heater. Both solar and ambient air energies are absorbed at the collector/evaporator and pumped to the storage tank via a Rankine refrigeration cycle and a thermosyphon heat exchanger. The condenser releases condensing heat of the refrigerant to the water side of the thermosyphon heat exchanger for producing a natural-circulation flow in the thermosyphon loop. A 105-liter ISAHP using a bare collector and a small R134a reciprocating-type compressor with rated input power 250 W was built and tested in the present study. The ISAHP was designed to operate at an evaporating temperature lower than the ambient temperature and a matched condition (near saturated vapor compression cycle and compressor exhaust temperature <100°C). A performance model is derived and found to be able to fit the experimental data very well for the ISAHP. The COP for the ISAHP built in the present study lies in the range 2.5–3.7 at water temperature between 61 and 25°C. 相似文献