垂直螺旋盘管地源热泵供暖制冷实验研究

结合一实际用户建立垂直螺旋盘管地源热泵实验系统，在供暖制冷工况下测量地下盘管的进出水温度，盘管从地下的取热量、排热量，从而分析系统性能、供热、制冷系数。     

The quantitative evaluation of design parameter's effects on a ground source heat pump system

The main solution for the reduction of energy consumption in the field of HVAC is the development of new and renewable energy technologies. Among the various renewable energy systems, ground source heat pump (GSHP) systems have been spotlighted as efficient building energy systems because of their great potentials for energy reduction in building air conditioning and reducing CO₂ emissions. However, higher initial cost works as a barrier to the promotion of their use. Therefore, it is critical to reduce the initial costs by optimizing the design of the system. In this paper, parameters that affect the performance of the GSHP system and the size of ground loop heat exchanger (GLHX) have been investigated. Ratio of GLHX length to unit capacity (L/Q) decreased according to increasing value of thermal conductivity, but L/Q increased according to increasing value of borehole heat transfer resistance. In cooling mode, L/Q decreased according to increasing EWT of underground circulating water and borehole distance but increased in heating mode. The value of L/Q tended to increase according to increasing underground initial temperature in cooling mode, but decreased in heating mode. L/Q decreased according to increasing U-tube separation distance and decreasing underground circulating water flow rate, because the thermal interference effect of underground circulating water and heat absorption and emission rate from the ground decreased. The reduction of the size of GLHX is very important in the aspect of saving total installation cost of a GSHP system. Therefore, the size of GLHX and the performance of GSHP system should be considered together for optimum design of the GSHP system.     

Experimental study of horizontal ground source heat pump performance for mild climate in Turkey

The aim of this study is to evaluate the performance of horizontal GSHP by considering various system parameters for winter climatic condition of Bursa, Turkey. For this purpose, a previously used experimental facility on cooling cycle [Coskun S, Pulat E, Unlu K, Yamankaradeniz R. Experimental performance investigation of a horizontal ground source compression refrigeration machine. International Journal of Energy Research 2008; 32: 44–56] was modified for the heating cycle. Soil thermal conductivity estimation was expanded and discussed. Preliminary numerical temperature distribution around GHE pipes was obtained. Tests were performed under laboratory conditions for space heating from December 2004 to March 2005. Variations of entering and leaving antifreeze solution temperatures, extracted heat from ground and rejected heat to the test room, super heat rate in evaporator and subcooling rate in condenser, total power consumption and coefficient of performance (COP) values for both the entire system and only heat pump unit (HPU) were obtained. Effect of outdoor temperature on system capacities and COP values with respect to outdoor air and mean soil temperatures were also presented. The COP of the entire system and HPU lie between 2.46–2.58 and 4.03–4.18, respectively. GSHP system was compared to conventional heating methods in the economical analysis and it was shown that the GSHP system is more cost effective than the all other conventional heating systems.     

Exergetic performance evaluation of heat pump systems having various heat sources

In this study heat pump systems having different heat sources were investigated experimentally. Solar‐assisted heat pump (SAHP), ground source heat pump (GSHP) and air source heat pump (ASHP) systems for domestic heating were tested. Additionally, their combination systems, such as solar‐assisted‐ground source heat pump (SAGSHP), solar‐assisted‐air source heat pump (SAASHP) and ground–air source heat pump (GSASHP) were tested. All the heat pump systems were designed and constructed in a test room with 60 m² floor area in Firat University, Elazig (38.41°N, 39.14°E), Turkey. In evaluating the efficiency of heat pump systems, the most commonly used measure is the energy or the first law efficiency, which is modified to a coefficient of performance for heat pump systems. However, for indicating the possibilities for thermodynamic improvement, inadequate energy analysis and exergy analysis are needed. This study presents an exergetic evaluation of SAHP, GSHP and ASHP and their combination systems. The exergy losses in each of the components of the heat pump systems are determined for average values of experimentally measured parameters. Exergy efficiency in each of the components of the heat pump systems is also determined to assess their performances. The coefficient of performance (COP) of the SAHP, GSHP and ASHP were obtained as 2.95, 2.44 and 2.33, whereas the exergy losses of the refrigerant subsystems were found to be 1.342, 1.705 and 1.942 kW, respectively. The COP of SAGSHP, SAASHP and GSASHP as multiple source heat pump systems were also determined to be 3.36, 2.90 and 2.14, whereas the exergy losses of the refrigerant subsystems were approximately 2.13, 2.996 and 3.113 kW, respectively. In addition, multiple source heat pump systems were compared with single source heat pump systems on the basis of the COP. Exergetic performance coefficient (EPC) is introduced and is applied to the heat pump systems having various heat sources. The results imply that the functional forms of the EPC and first law efficiency are different. Results show that Ex_loss,total becomes a minimum value when EPC has a maximum value. Copyright © 2008 John Wiley & Sons, Ltd.     

地源热泵在室内游泳池供暖空调中的应用研究

在分析了地源热泵系统的特点和概算了室内游泳池的冷热负荷的基础上，提出采用地源热泵系统可同时满足室内游泳池的供暖、空调及池水加热3项需求；分析了不同季节地源热泵在游泳池的运行工况。通过分析比较表明，地源热泵系统的运行费用比传统的冷水机组加燃油锅炉系统的运行费用节省约50％，比冷水机组加燃气锅炉系统的运行费用节省21％。     

Performance evaluation and modeling of a hybrid cooling system combining a screw water chiller with a ground source heat pump in a building

The performance of a hybrid cooling system that combines a screw water chiller with a ground source heat pump (GSHP) was measured and analyzed at various cooling loads. In addition, the hybrid cooling system in a building was modelled sophisticatedly using EnergyPlus and then validated with the measured data. The coefficient of performance of the GSHP was lower than that of a conventional chiller in the monitored building, but the hybrid cooling system helped to stably provide the required cooling capacity at high-load conditions. The mean bias error and the normalized root-mean squared error of the predicted cooling load of the building were −8% and 12.4%, respectively. The hybrid cooling system was simulated by varying four operating parameters: the operating schedule, chilled water temperature (T_CW), dry-bulb temperature (T_DB), and entering water temperature (T_EW). The T_CW is ascertained as being the most effective control parameter in the hybrid cooling system.     

Investigation on the feasibility and performance of ground source heat pump (GSHP) in three cities in cold climate zone,China

As a renewable energy technology, ground source heat pump (GSHP) system is high efficient for heating and cooling in office buildings. However, this technology has strong dependence on the meteorological and building envelope thermal characteristic parameters. For the purpose of quantitative investigation on the feasibility and performance GSHP, three cities located in cold climate zone, Qiqihaer, Shenyang and Beijing, were sampled. Firstly, the office building dynamic loadings in these cities were calculated on basis of the different meteorological and envelope thermal characteristic parameters. The TRNSYS, one kind of energy simulation software, were employed to simulate the operation performances of GSHP on basis of these parameters. The simulation revealed the data on the outlet/inlet temperature of buried pipes, soil temperature, energy consumption distribution and the coefficient of performance (COP) for one year operation. Furthermore, ten years operation was also simulated to show the stability of the performance based on the outlet/inlet temperature of buried pipes and soil temperature. From these results, the GSHP had shown its most suitable performance in Beijing, second in Shenyang and worst in Qiqihaer. These results could be used as a reference on suitable utilization of GSHP systems in office buildings located in cold climate zone, China.     

Experimental study of vertical ground-source heat pump performance evaluation for cold climate in Turkey

Heat pump systems are recognized to be outstanding heating, cooling and water heating systems. They provide high levels of comfort as well as offering significant reductions in electrical energy use. In addition, they have very low levels of maintenance requirements and are environmentally attractive. The purpose of this study is to evaluate the experimentally performance and energy analysis of vertical ground-source heat pump (GSHP) for winter climatic condition of Erzurum, Turkey. For this aim, an experimental analysis was performed on GSHP system made up in the Energy Laboratory in the campus of Ataturk University. The experimental apparatus consisted of a ground heat exchanger, the depth of which was 53 m, a liquid-to-liquid vapor compression heat pump, water circulating pumps and other measurement and control equipments. Tests were performed under laboratory conditions for space heating, in which experimental results were obtained during January–May within the heating season of 2007. The experimentally obtained results were used to calculate the heat pump coefficient of performance (COP) and the system performance (COPs). The COP and COPs were found to be in the range of 2.43–3.55 and 2.07–3.04, respectively. This study also shows that the system proposed could be used for residential heating in the province of Erzurum which is one of the coldest climate region of Turkey.     

提高地能利用的强化传热试验研究

以太阳辐射积聚大量能量和冷热良性循环蓄集巨大能量的地下是一个庞大的可再生能源库，也是一项可充分利用的自然能量资源。该文介绍了在地源热泵系统中开展的地下100m和200m竖直井闭式循环传热的研究工作，提出利用地下螺旋芯管束新方法，加强旋流流动，提高地下换热能力。试验表明，在放热和吸热过程中，传热均得到显著提高。所提出的可控制间歇过程，将充分发挥换热井的换热能力，实现最少的井数布置，保证良好的地源热泵机组运行工况。     

太阳能与土壤源耦合供暖系统的实验研究

在分析太阳能、土壤源热泵及联合供热特点的基础上,研究了太阳能热泵独立系统、土壤源耦合热泵系统运行模式的制热性能和节能效果,建立了太阳能蓄能-热泵耦合热泵系统的供暖模式及优化模型.通过采暖季初期的太阳能蓄能、供暖,土壤源热泵独立供暖及太阳能-土壤源耦合热泵供热的实验研究,验证了太阳能-土壤源耦合热泵供暖模式的可行性和经济...     

Global warming’s impact on the performance of GSHP

Since heating and cooling systems of buildings consume 30–50% of the global energy consumption, increased efficiency of such systems means a considerable reduction in energy consumption. Ground source heat pumps (GSHP) are likely to play a central role in achieving this goal due to their high energy efficient performance. The efficiency of GSHP depends on the ground temperature, heating and cooling demands, and the distribution of heating and cooling over the year. However, all of these are affected by the ongoing climatic change. Consequently, global warming has direct effects on the GSHP performance. Within the framework of current study, heating and cooling demands of a reference building were calculated for different global warming scenarios in different climates i.e. cold, mild and hot climate. The prime energy required to drive the GSHP system is compared for each scenario and two configurations of ground heat exchangers. Current study shows that the ongoing climatic change has significant impact on GSHP systems.     

Comprehensive exergy analysis of a ground-source heat pump system for both building heating and cooling modes

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.     

竖直埋管地热换热器钻孔内的传热分析

准三维模型为竖直埋管地热换热器的结构优化提供了较为精确的理论基础。利用准三维模型对竖直埋管地热换热器进行分析与研究得出，不同的行程布置对双U型埋管地热换热器的传热性能有较大影响。就钻孔内热阻的对比，双U型埋管比单U型埋管钻孔内的热阻低，因而双U型埋管地热换热器较单U型埋管地热换热器更为合理。     

A performance comparison between an air‐source and a ground‐source reversible heat pump

In this study, the performance of a reversible ground‐source heat pump coupled to a municipality water reticulation system, is compared experimentally and with simulations to a conventional air‐source heat pump for space cooling and heating. A typical municipality water reticulation system comprises hundreds of kilometres of pipes designed in loops that will ensure adequate circulation of water. This results in a substantial heat exchanger with great potential. Indirect heat transfer occurs between the refrigerant and ground via the municipality water reticulation system that acts as the water‐to‐ground heat exchanger. The experimental and simulated comparisons of the ground‐source system to the air‐source system are conducted in both the cooling and the heating cycles. Climatalogical statistics are used to calculate the capacities and coefficients of performance of the ground‐source and air‐source heat pumps. Results obtained from measurements and simulations indicate that the utilization of municipality water reticulation systems as a heat source/sink is a viable method of optimizing energy usage in the air conditioning industry, especially when used in the heating mode. Copyright © 2001 John Wiley & Sons, Ltd.     

A study on the performance of a geothermal heat exchanger under coupled heat conduction and groundwater advection

Being environmental friendly and with the potential of energy-efficiency, more and more ground-source heat pump (GSHP) systems are being widely used. However, the influence of groundwater advection on the performance of the geothermal heat exchanger (GHE) in a GSHP is not still clearly known. In this paper, the configuration of a vertical dual-function GHE used in an integrated soil cold storage and ground-source heat pump (ISCS&GSHP) system, which charged cold energy to soil at night and produced chilled water in daytime in summer, and hot water for heating in winter, is firstly presented. This is then followed by a report on a mathematical model for the GHE considering the impact of the coupled heat conduction and groundwater advection on the heat transfer between the GHE and its surrounding soil. The GHE model developed was then integrated into a previously developed simulation program for an ISCS&GSHP system, and the operating performances of the GHE in an ISCS&GSHP system having a vertical dual-function GHE have been studied by simulation and reported. These simulation results, firstly seen in open literature, are much helpful to the design of a GHE buried in soil and widely used in GSHP systems or ISCS&GSHP systems.     

Cooling characteristics of ground source heat pump with heat exchange methods

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.     

Experimental performance evaluation of a closed‐loop vertical ground source heat pump in the heating mode using energy analysis method

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.     

Theoretical study on the performance of an integrated ground-source heat pump system in a whole year

Being environmental friendly and with the potential of energy-efficiency, ground-source heat pump (GSHP) systems are widely used. However, in southern China, there exists large difference between cooling load in summer and heating load in winter. Thus the increase of soil temperature gradually year-by-year will decrease the COP of the GSHP system. In this paper, the configuration of a vertical dual-function geothermal heat exchanger (GHE) used in an integrated soil cold storage and ground-source heat pump (ISCS&GSHP) system, which charged cold energy to the soil at night and produced chilled water at daytime in summer, and supplied hot water for heating in winter, is presented. This is then followed by reporting the development of the mathematical model for the GHE considering the impact of the coupled heat conduction and groundwater advection on the heat transfer between the GHE and its surrounding soil. The GHE model developed was then integrated with a water-source heat pump and a building energy simulation program together for a whole ISCS&GSHP system. Then the operation performance of the ISCS&GSHP system used for a demonstration building is studied. These simulation results indicated the system transferred 71.505% of the original power consumption at daytime to that at nighttime for the demonstration building. And the net energy exchange in the soil after one-year operation was only 2.28% of the total cold energy charged. Thus we can see the feasibility of the ISCS&GSHP system technically.     

Numerical and experimental assessment of thermal performance of vertical energy piles: An application

A district space heating and cooling system using geothermal energy from bearing piles was designed in Shanghai and will be installed in two years before 2010. This paper describes the pile-foundation heat exchangers applied in an energy pile system for an actual architectural complex in Shanghai, 30% of whose cooling/heating load was designed to be provided by a ground-source heat pump (GSHP) system using the energy piles. In situ performance tests of heat transfer are carried out to figure out the most efficient type of energy pile and to specify the design of energy pile system. Numerical investigation is also performed to confirm the test results and to demonstrate the medium temperature variations along the pipes. The averaged heat resistance and heat injection rate of different types of energy piles are calculated from the test and numerical results. The effect of pile type, medium flow rate and inlet temperature on thermal performance is separately discussed. From the viewpoint of energy efficiency and adjustability, the W-shaped underground heat exchanger with moderate medium flow rate is finally adopted for the energy pile system.     

寒冷地区土壤源热泵冷热源系统设计方案研究

针对由于空调建筑全年所需的冷量和热量的不均衡性,使得土壤的年吸、释热量不平衡,从而将导致系统在连续多年运行后,热泵机组的运行效率不断下降,甚至会出现停机现象,该文以北京地区某一建筑的土壤源热泵系统为例,提出了增加辅助散热设备-冷却塔的设计方法,并利用TRNSYS模拟软件对冷却塔与埋管换热器的不同连接方式,即串联和并联,进行了模拟计算,得出了可保证土壤源热泵系统长期高效运行的各种设计方案,为在寒冷地区正确设计土壤源热泵系统提供了具体的解决办法.