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A thermoeconomic analysis of a ground‐source heat pump (GSHP) system with a vertical or horizontal ground heat exchanger, a type of heat delivery system, was performed using the modified productive structure analysis method. In this analysis, the unit cost of geothermal heat delivered to a room using GSHP system was estimated. The unit cost of heat delivered was calculated to be $0.063/kWh for input of electricity with a unit cost of $0.140/kWh for a GSHP with a coefficient of performance (COP) of 3.27. Exergy destruction and monetary losses due to the irreversibility that occurs at each component of the system were also estimated. The unit cost of heat was found to be inversely proportional to the COP of the heat pump and proportional to the electricity input. The greatest monetary loss occurs in the geothermal heat exchanger in which considerable mass of brine flows in long pipes and in the fan‐coil unit which features a complex configuration of pipes in the air passages, respectively. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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In evaluating the efficiency of heat pump (HP) systems, the most commonly used measure is the energy (or first law) efficiency, which is modified to a coefficient of performance (COP) for HP systems. However, for indicating the possibilities for thermodynamic improvement, energy analysis is inadequate and exergy analysis is needed. This study presents an exergetic assessment of a ground‐source (or geothermal) HP (GSHP) drying system. This system was designed, constructed and tested in the Solar Energy Institute of Ege University, Izmir, Turkey. The exergy destructions in each of the components of the overall system are determined for average values of experimentally measured parameters. Exergy efficiencies of the system components are determined to assess their performances and to elucidate potentials for improvement. COP values for the GSHP unit and overall GSHP drying system are found to range between 1.63–2.88 and 1.45–2.65, respectively, while corresponding exergy efficiency values on a product/fuel basis are found to be 21.1 and 15.5% at a dead state temperature of 27°C, respectively. Specific moisture extraction rate (SMER) on the system basis is obtained to be 0.122 kg kW?1 h?1. For drying systems, the so‐called specific moisture exergetic rate (SMExR), which is defined as the ratio of the moisture removed in kg to the exergy input in kW h, is also proposed by the authors. The SMExR of the whole GSHP drying system is found to be 5.11 kg kW?1 h?1. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Yusuf Ali Kara 《国际能源研究杂志》2007,31(15):1504-1516
An experimental study is performed to determine the performance of a ground source heat pump (GSHP) system in the heating mode in the city of Erzurum, Turkey. The GSHP system using R‐134a as refrigerant has a single U‐tube ground heat exchanger (GHE) made of polyethylene pipe with a 16 mm inside diameter. The GHE was placed in a vertical borehole with 55 m depth and 203.2 mm diameter. The average coefficients of performance (COP) of the GSHP system and heat pump in heating mode are calculated as 2.09 and 2.57, respectively. The heat extraction rate per meter of the borehole is determined as 33.60 W m?1. Considering the current gas and electric prices in Erzurum city, the equivalent COP of the GSHP system should be 2.92 for the same energy cost comparing with natural gas. The virgin ground in Erzurum basin has high permeability and low thermal conductivity. In order to improve the thermal efficiency of GHE and thus improve COP of a GSHP in the basin, the borehole should be backfilled with sand as low‐cost backfill material and a 1 to 2 m thick surface plug of clay should be inserted. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Comprehensive exergy analysis of a ground-source heat pump system for both building heating and cooling modes 总被引:2,自引:0,他引:2
This paper presents a comprehensive exergy analysis of three circuits and whole system of a ground-source heat pump (GSHP) for both building heating and cooling modes. The purpose is to search out the key potential energy saving components. The analytical formulae of exergy loss, exergy efficiency, exergy loss ratio, exergy loss coefficient and thermodynamic perfect degree are derived, respectively. The results show that these exergy indexes should be used integratively, and in the whole system the location of maximum exergy loss ratio is the compressor, while the location of minimum exergy efficiency and thermodynamic perfect degree is the ground heat exchanger, so that the compressor and the ground heat exchanger should be primarily improved. The results also indicate that the exergy loss of a GSHP system for building heating mode is bigger than that of cooling mode, and the exergy efficiency of a whole GSHP system is obviously lower than those of its components for both building heating and cooling modes. Therefore, a comprehensive exergy analysis of a GSHP should be paid more attention to. The results may provide guidelines for the design and optimization of GSHP systems. 相似文献
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Yujin Hwang Jae-Keun Lee Young-Man Jeong Kyung-Min Koo Dong-Hyuk Lee In-Kyu Kim Sim-Won Jin Soo H. Kim 《Renewable Energy》2009,34(3):578-582
This paper presents the cooling performance of a water-to-refrigerant type ground heat source heat pump system (GSHP) installed in a school building in Korea. The evaluation of the cooling performance has been conducted under the actual operation of GSHP system in the summer of year 2007. Ten heat pump units with the capacity of 10 HP each were installed in the building. Also, a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth was constructed for the GSHP system. To analyze the cooling performance of the GSHP system, we monitored various operating conditions, including the outdoor temperature, the ground temperature, and the water temperature of inlet and outlet of the ground heat exchanger. Simultaneously, the cooling capacity and the input power were evaluated to determine the cooling performance of the GSHP system. The average cooling coefficient of performance (COP) and overall COP of the GSHP system were found to be ~8.3 and ~5.9 at 65% partial load condition, respectively. While the air source heat pump (ASHP) system, which has the same capacity with the GSHP system, was found to have the average COP of ~3.9 and overall COP of ~3.4, implying that the GSHP system is more efficient than the ASHP system due to its lower temperature of condenser. 相似文献
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S.P. Lohani 《Energy》2010
In this paper, we deal with the energy and exergy analysis of a fossil plant and ground and air source heat pump building heating system at two different dead-state temperatures. A zone model of a building with natural ventilation is considered and heat is being supplied by condensing boiler. The same zone model is applied for heat pump building heating system. Since energy and exergy demand are key parameters to see which system is efficient at what reference temperature, we did a study on the influence of energy and exergy efficiencies. In this regard, a commercial software package IDA-ICE program is used for calculation of fossil plant heating system, however, there is no inbuilt simulation model for heat pumps in IDA-ICE, different COP (coefficient of performance) curves of the earlier studies of heat pumps are taken into account for the evaluation of the heat pump input and output energy. The outcome of the energy and exergy flow analysis at two different dead-state temperatures revealed that the ground source heat pumps with ambient reference have better performance against all ground reference systems as well as fossil plant (conventional system) and air source heat pumps with ambient reference. 相似文献
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我国地源热泵相关技术专利综合分析 总被引:1,自引:1,他引:0
地源热泵是一种利用浅层土壤或含水层实现供热和空调制冷的高效节能设备。随着我国政府和社会对节能环保越发重视,地源热泵技术的优势将更加突出。最近几年我国地源热泵发展较迅速,在设计、制造、运行、管理等方面都取得了一些研究成果。对国内最近地源热泵的相关专利进行了检索,并进行了定性与定量分析,为该领域的研究者和企业提供专利信息参考,并归纳总结了一些研究热点,以期为我国地源热泵行业的研究开发与市场发展提供决策参考和技术依据。 相似文献
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The objective of this study is to investigate the influence of the cooling performance for a water-to-water ground source heat pump (GSHP) by using the counter flow and parallel flow methods. The GSHP uses R-410A as a refrigerant, and its main components are a scroll compressor, plate heat exchangers as a condenser, an evaporator, a thermostatic expansion valve, a receiver, and an inverter. Based on our modeling results, the heat transfer rate of the counter flow evaporator is higher than that of the parallel flow evaporator for a heat exchanger length greater than 0.42 m. The evaporator length of the GSHP used in this study was set to over 0.5 m. The performance of the water-to-water GSHP was measured by varying the compressor speed and source-side entering water temperature (EWT). The cooling capacity of the GSHP increased with increased compressor RPMs and source side EWT. Also, using the counter flow method, compared to the parallel flow method, improves the COP by approximately 5.9% for an ISO 13256-2 rated condition. 相似文献
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Analytical and experimental studies were performed on a direct‐expansion solar‐assisted heat pump (DX‐SAHP) water heating system, in which a 2 m2 bare flat collector acts as a source as well as an evaporator for the refrigerant. A simulation model was developed to predict the long‐term thermal performance of the system approximately. The monthly averaged COP was found to vary between 4 and 6, while the collector efficiency ranged from 40 to 60%. The simulated results were used to obtain an optimum design of the system and to determinate a proper strategy for system operating control. The effect of various parameters, including solar insolation, ambient temperature, collector area, storage volume and speed of compressor, had been investigated on the thermal performance of the DX‐SAHP system, and the results had indicated that the system performance is governed strongly by the change of solar insolation, collector area and speed of compressor. The experimental results obtained under winter climate conditions were shown to agree reasonably with the computer simulation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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In this paper, an experimental performance evaluation of a direct expansion ground‐coupled heat pump (DX‐GCHP) system in heating mode is presented. The DX‐GCHP uses R134a as the refrigerant, and consists of three single U‐tube copper ground heat exchangers (GHEs) placed in three 30 m vertical boreholes. During the on–off operations from December 25, 2007, to February 6, 2008, the heat pump supplied hot water to fan‐coil at around 50.4°C, and its heating capacity was about 6.43 kW. The energy‐based heating coefficient of performance (COP) values of the heat pump and the whole system were found to be on average 3.55 and 3.28 at an evaporating temperature of 3.14°C and a condensing temperature of 53.4°C, respectively. The second law efficiency on the DX‐GCHP unit basis was around 0.36. The exergetic COP values of the heat pump and the whole system were obtained to be 0.599 and 0.553 (the reference state temperature was set equal to the average outdoor temperature of ?1.66°C during the tests), respectively. The authors also discussed some practical points such as the heat extraction rate from the ground, refrigerant charge and two possible new configurations to simultaneously deal with maldistribution and instability of parallel GHE evaporators. This paper may reveal insights that will aid more efficient design and improvement for potential investigators, designers and operators of such DX‐GCHP systems. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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利用生命周期评价方法(LCA)对土壤源热泵与空气源热泵在节能和CO2减排效益方面进行研究比较,考察了土壤源热泵相对于空气源热泵的能耗回收期(EPT)和CO2回收期(CPT)两个指标,结果表明,整个生命周期内土壤源热泵较空气源热泵节能91829.64t标准煤,CO2减排262.5t,相对能耗回收期为2.87a,CO2回收期为0.89 a。 相似文献
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Ground source heat pumps (GSHP) are attractive alternatives to conventional heating and cooling systems owing to their higher energy utilization efficiency. In this paper, the effect of various system parameters on GSHP performance is studied using a computer model. Also, a comparative economic evaluation is carried out to assess the feasibility of using a GSHP in place of conventional heating/cooling systems and an air source heat pump. The results indicate that system parameters can have a significant effect on performance, and that GSHP is economically preferable to conventional systems. © 1997 John Wiley & Sons, Ltd. 相似文献
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A distributed model of an air-source heat pump (ASHP) system and its experimental setup using an immersed water condenser were presented. Dynamic performance of the ASHP was then evaluated by both simulation and experiment. The results indicated that the system coefficient of performance (COP) decreased as the condenser temperature increased, ranging from 4.41 to 2.32 with the average COP equaling 3.29 during the experiment. Comparisons between simulation results and experimental measurements demonstrated that the model was able to yield satisfactory predictions. Furthermore, temperature profiles of the refrigerant in the evaporator and condenser were also given. This paper provides the theoretical and experimental background for ASHP system optimization and a valuable reference for a solar air-source heat pump water heater when the solar irradiation energy is insufficient on cloudy or rainy days. 相似文献
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A study is presented on the characteristics of the air source heat pump (ASHP) under two kinds of typical mal-defrost phenomena. The definition of the “Mal-defrost phenomena” is put forward, and the possible origins of their occurrence are analyzed. It is concluded that the current defrost strategies may cause mal-defrost phenomena due to the lack of the direct control information, frost thickness. Transient characteristics of the tested ASHP under these mal-defrost phenomena are investigated by field tests. Instant frosting images are captured to record the dynamic frosting process. In the first phenomenon of mal-defrost, the defrost control is carried out over an hour after a “critical” level of frosting has been reached. It reduces the COP and heating capacity by about 17.4% and 29%, respectively. In the second phenomenon of mal-defrost, three defrost operations occur while almost no frost is observed on the heat exchanger during 6 h testing period. It causes 4.2% decrease for the heating efficiency. 相似文献