共查询到20条相似文献,搜索用时 93 毫秒
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热泵间歇制热及土壤热响应特性的研究 总被引:1,自引:0,他引:1
研究了广东地区地源热泵机组间歇式运行模式下埋地管换热器的换热能力及土壤热响应特性。土壤源热泵系统的单U、双U埋地管换热器深30m,在连续运行工况下,系统运行12h后土壤温度变化很小,单U和双U井的土壤平均温度分别下降5.16℃和6.30℃,系统停机后自然恢复到初始温度需要长达75h。分别取开停时间比3h:5h和4h:5h进行实验,并比较了间歇和连续两种工况下地埋管换热能力的大小,发现间歇工况下单U井的换热能力可分别提高8.3%和7.6%,双U井可分别提高10.2%和3.1%。 相似文献
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西北地区地源热泵工程运用分析 总被引:3,自引:0,他引:3
结合具体工程案例,本文分析了地源热泵技术在西北地区的工程运用及设计步骤。文中详细介绍了地埋管换热器的换热特性测试系统及测试方法,并依照测试结果,设计地源热泵联合太阳能系统。通过对垂直U形地埋管换热器冬夏季取热和排热测试,分析不同换热工况下单双U管换热器换热特性,结合当地钻孔难度大以及地埋管换热器取热量小的特点,采用双U地埋管换热器。测试过程中,对不同入口温度、流量工况换热能力进行测试分析,提出在某些地区,地源热泵工程设计采用"大流量,小温差"的设计理念。 相似文献
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Computer simulation and analysis of a ground source heat pump system with horizontal ground heat exchangers operating in heating (max 5.5 kW) and cooling (max 3.3 kW) mode was carried out for a typical residential house, with 200 m2 of living space, located in Sapporo (Japan). In spite of high electricity rate, the ground source heat pump system is more beneficial alternative for space heating than an oil furnace and an electric resistance system. Besides, the heat pump technology offers relatively low thermal degradation of the ground environment, lower cost of heating and cooling, higher operating efficiency than electric resistance heating or air-source heat pump and is environmentally clean, i.e. without greenhouse gas emission, if the electricity is generated from renewable energy resources, such as wind and solar. The use of the cooling mode can provide further benefits like a shorter investment payback and human thermal comfort in summer. As a result, application of horizontal loops for new and retrofit residential and commercial use in northern Japan is feasible particularly in farmland areas. 相似文献
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土壤源热泵是利用土壤作为吸热和排热源的一种高效、节能、环保的热泵技术,近年来得到了快速的发展。本文介绍了一种简化的土壤与埋地换热器的传热数学模型,并利用Foxpro编制了简便、快速的计算程序。 相似文献
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O. J. Svec 《国际能源研究杂志》1987,11(4):573-581
This paper presents a historical background of ground source heat pump technology, followed by a review of its current shortcomings. Based on these observations the author assesses the R&D needs and recommendations for future research. 相似文献
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为了增强土壤源热泵系统地下埋管换热器的换热性能,通过CFD方法,探讨改用波纹管对地下换热所产生的影响,首次提出采用波纹管代替光管作为强化地下埋管换热器换热效率。 相似文献
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A high-efficiency ground heat exchanger has been developed for use with ground-source heat pumps. The exchanger is made of copper tubing, shaped in the form of a spiral, which can be installed in a vertical borehole backfilled with sand. Thermal performance of a full-scale prototype indicated that this heat exchanger can achieve very high heat extraction rates if subfreezing operating temperatures are used. For most soil types cyclic freezing and thawing is not a problem; however, for the sensitive Leda clay in which the prototype tests were conducted, substantial settlement occurred after the first freeze-thaw cycle owing to initial collapse of the soil structure. 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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The total thermal flux at the surface of ‘steaming ground’ consists of a convective and a conductive component, even in the absence of any visible steam discharge at the surface. The total flux and its convective component can be measured separately and directly using a water-filled ground calorimeter. The conductive component is given by the difference between the two fluxes, but can also be assessed independently using measured near-surface soil parameters and temperature gradients, retaining the thermal conductivity as parameter. The conductivity is controlled, in turn, by the thermal diffusivity and the specific moisture content of the near-surface layer. The observed total flux values range between 0.03 and 2 kW/m2 at sites where boiling temperatures occur at depths of about 4 m and <0.1 m, respectively; the convective flux can reach 50% of the total flux at most sites. Analysis of various soil parameters and soil temperature sections points to a ‘heat pipe’ transfer mechanism that maintains a high conductive transfer in a thin near-surface layer where sub-surface steam condensation is enhanced. An empirical power-law function can be used to assess the total heat flux from the boiling point depth at single sites with known soil temperature profiles. 相似文献
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M. M. Salah El-Din 《Renewable Energy》1999,18(4):1
Two expressions have been developed to predict the periodic variation of the ground temperature with depth. They are based on the energy balance equation at the ground surface and the assumption that the temperature variation at the ground surface is in the form of a sine-wave or a Fourier series. The energy balance equation involves the periodic variation of solar radiation, atmospheric temperature and the latent heat flux due to evaporation. The heat flux into the ground has been derived and the damping depth and the corresponding ground temperature have been calculated. A parametric study showed that the ground temperature and the amplitude of the heat flux into the ground increase with the increasing in the air relative humidity and the ground absorptivity. Conversely, they decrease with the increasing in the evaporation fraction and wind speed. The values of the damping depth is almost the same while the corresponding ground temperature is influenced by the various parameters significantly. 相似文献