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《可再生能源》2016,(5)
运行模式对地埋管换热器的热交换性能具有显著影响。文章借助桂林理工大学建立的地源热泵实验平台,对桂林地区地源热泵制冷工况下3种运行模式进行试验,研究地源热泵的运行状况及管壁温度变化特性,分析运行模式对地埋管热交换性能的影响规律。研究结果表明:3种运行工况下,地源热泵机组的性能系数COP分别为4.30,4.03,3.48,竖埋管单位管长换热量为14.4~32.8 W/m,水平埋管单位管长换热量为14.8~17.9W/m;地埋管的管壁温度随着地源热泵的运行发生变化,其恢复程度与停机时间的长短有关;间歇运行模式有利于土壤温度场的恢复,提高地埋管换热器的热交换性能;停运比Ps-o由0变化到1时,热泵机组性能系数COP增加了15.8%。 相似文献
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为了研究地埋管换热器在变负荷下连续运行与间歇运行的换热性能,基于有限长线热源渗流模型建立竖直地埋管钻孔外准三维非稳态传热模型,应用叠加原理计算钻孔群中钻孔壁温度场及地埋管内流体温度场。在存在地下水水平渗流的情况下,研究了变负荷连续运行模式下不同渗流速度、不同运行工况及不同钻孔位置对地埋管换热器的换热性能的影响。结果表明,在连续运行模式下,边缘位置的钻孔及较大的渗流速度能够增强地埋管换热器的换热性能;在间歇运行模式下,地埋管换热器的运行份额越小,其制冷效果越好,反之,制冷效果越差;在间歇运行工况下,土壤温度能在系统间歇期内得到一定程度的恢复,从而更好地提高地热能的利用率。 相似文献
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为了确定渗流对竖直地埋管换热器换热性能的影响,基于多孔介质传热理论与Darcy定律,利用多物理场耦合软件COMSOL建立了三维热渗耦合模型,模拟了有无渗流条件下竖直地埋管换热器周围土壤温度场的变化。结果表明,地下水渗流有助于竖直地埋管换热器换热,且渗流速度越大,竖直地埋管换热器换热效果越明显;平行于渗流方向处温度场偏向下游,垂直于渗流方向处温度场始终保持对称分布,渗流速度由0m/s增大到1.0×10-5 m/s时,对应热作用半径由0.42m减小到0.32m。 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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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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在冬冷夏热且夏季冷负荷远大于冬季热负荷的地区常采用带有冷却塔的复合式地源热泵系统,其控制策略存在极大的优化空间。文章提出了直接比较冷却塔和与土壤换热器相连的板式换热器的出口温度的控制方法,并通过人工神经网络预测板式换热器机组侧的出口水温来实现此控制方法。通过FLUENT软件建立复合式地源热泵系统动态数值模型,获取建立神经网络的数据,采用3层BP网络,建立了多个预测板式换热器机组侧出口温度的模型。研究结果表明,采用神经网络可以准确实现此预测,绝对误差不超过0.4℃。 相似文献
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M. H. Sharqawy E. M. Mokheimer M. A. Habib H. M. Badr S. A. Said N. A. Al‐Shayea 《国际能源研究杂志》2009,33(6):582-592
This paper presents energy, exergy and uncertainty analyses for the thermal response test of a ground heat exchanger. In this study, a vertical U‐shaped ground heat exchanger with 80 m depth and 20 cm borehole diameter is installed for the first time at the university premises in Saudi Arabia. A mobile thermal response apparatus is constructed and used to measure the performance of the ground heat exchanger. The thermal response test was carried out four times at different thermal loads from September 2007 to April 2008. The energy and exergy transports of these thermal response tests were analyzed using the experimental results obtained in this period. The analysis provides a better understanding of the overall performance of vertical ground heat exchangers, verifies the thermal response test results and improves the experimental setup. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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M. Piechowski 《国际能源研究杂志》1998,22(11):965-979
Validation of ground heat exchanger (GHE) model is presented using the experimental data obtained for both single and double pipe horizontal GHE. Sensitivity analysis of the GHE model shows the influence of the variation in the soil thermal conductivity, specific heat and density on the thermal performance of a GHE. Finally, the thermal performance of a GHE is analysed using both heat and mass transfer models, and conduction only model, as well as the influence of the initial soil moisture content on the thermal performance of a GHE. © 1998 John Wiley & Sons, Ltd. 相似文献
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地源热泵是一种利用土壤所储藏的太阳能资源作为冷热源进行能量转换的供暖制冷空调系统,通过输入少量的高品位能源(如电力、机械功、燃气和液体燃料),实现热量从低温热源向高温热源的转移.以上海某小型别墅为对象,设计了一套家用地源热泵空调系统.首先计算了夏季冷负荷和冬季热负荷,然后根据冷、热负荷选择一套水源热泵机组(MWH080CR型机组)和相应的风机盘管,进行了室内水管环路系统、土壤热交换器和地板采暖的设计选型,最后对系统的能效比进行了计算.结果表明,该空调系统具有节能环保、稳定可靠、舒适耐用等优点. 相似文献
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Novel methods are sought to provide greater efficiency of the installation of ground heat exchangers for GSHPs (ground source heat pumps) in domestic buildings. An economically viable option is to utilise concrete foundation piles as ground heat exchangers. The objective of this study is to investigate the operation of utilising a piled foundation structure as a ground heat exchanger. A test plot of 72 m2 (ground floor area) was produced with 21 × 10 m deep concrete piles, with a single U tube pipe in each. Ground heat was extracted by a heat pump with the heat loading being varied in line with the date and the average air temperature. Over the 2007/2008 heating season this study had investigated the temperature changes in the foundation piles and the surrounding ground in addition to the heat pump operational performance. The temperature changes observed in the region of the test plot were compared with variations naturally experienced in the ground due to the seasonal climatic influence. The SPF (seasonal performance factor) of the heat pump was 3.62 and the ground temperature at a distance of 5 m from the test plot was seen to be undisturbed by the heat extraction and followed the predicted seasonal variation. 相似文献