共查询到18条相似文献,搜索用时 93 毫秒
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建立地埋管换热土壤热湿迁移过程的实验装置,对地源热泵间歇运行时不同进口流体温度及不同土壤体积含水率下土壤温湿度场的变化特性进行实验研究。实验结果表明∶间歇运行时,入口流体温度的升高会使土壤温度最大值升高,但不利于土壤温度的恢复,土壤体积含水率的增加在一定程度上有利于地下换热和土壤温度的恢复。系统开机后存在土壤温度上升的主上升区,此区温度增幅超过65%,关机后第18小时土壤温度基本恢复至初始温度;系统关停后在温湿度梯度的作用下会出现温度和含水率最大值后移的现象,热源对土壤温度和含水率的作用半径约为280和375 mm;开停比为1∶2时温湿度较1∶1能恢复得更低,合理设置停机时间有利于机组长期有效运行。 相似文献
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土壤源热泵制冷间歇工况土壤温度响应实验研究 总被引:2,自引:0,他引:2
在夏热冬暖的广州地区搭建了两种换热器向土壤放热的实验台,换热器埋地深度为30m,实验元件有单U和双U两种型式.连续制冷工况下,通过对两口井内土壤温度变化的研究,结果发现,开机12h后,土壤温度趋于稳定;停机12h后两个埋地换热管处的土壤温度就可恢复约95%,但土壤温度基本得以恢复需要停机81h.在停机12h后地温恢复得极其缓慢,已没有工程应用价值.可见合理选择运行与停机时间有助于提升系统的整体换热能力和地热的综合利用率.通过实验研究发现,间歇工况下双U井单位井深换热量较之连续运行提高了25.6%,单U井单位井深换热量提高了21.8%. 相似文献
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不同运行方式对地源热泵系统的长期稳定性有着重要作用。以西安地区为例,建立了双U型地埋管换热器三维传热模型,模拟了不同运行方式对单孔和群孔换热器换热特性的影响。研究结果表明:地源热泵管群系统应间歇运行,每天最大负荷工况下连续运行不超过8 h;年总供冷热量差值控制在10%内,以便土壤温度恢复;3年和10年土壤温差分别控制在1℃和3℃内,以保证地源热泵系统长期供能效果。 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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Improved underground heat exchanger by using no-dig method for space heating and cooling 总被引:2,自引:0,他引:2
Yasuhiro Hamada Makoto Nakamura Hisashi Saitoh Hideki Kubota Kiyoshi Ochifuji 《Renewable Energy》2007,32(3):480-495
This paper describes experiments and analyses on an improved underground heat exchanger by using a no-dig method for the purpose of the cost reduction of a space heating and cooling system using underground thermal energy. First, the improved underground heat exchanger was installed on the campus of Hokkaido University, and it was shown that a ground source heat pump system utilizing the heat exchanger was sufficient for space heating and cooling. Second, evaluation program of the heat exchanger was developed, and the program was verified to give good predictions by comparing with experimental results. As a result of system simulations, an energy reduction for a system installation relative to a conventional vertical earth heat exchanger reached 78%. The primary energy reduction rate including the system installation and operation relative to a typical air source heat pump was 29%. 相似文献
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水源热泵技术利用少量电能将地表水或地下水的低品位能量转移至高品位,目前正成为节能领域的研究热点.针对水源热泵变冷凝参数的相关研究缺乏的现状,通过搭建水源热泵热水器实验台进行了相应实验研究.在水流量Q为0.7~1.3 m~3·h~(-1),进水温度t为15~30℃范围内,对系统功耗、制热量、制冷量、热泵性能系数COP等参数进行了测量.实验结果表明,在水流量为1.1 m~3·h~(-1),进水温度为20℃时,COP达到最大值,系统平均热泵性能系数COP_(ave)为3.23,此时系统处于最佳运行工况.由此可知,寻找系统的最佳运行工况对热泵系统设计和实际工程应用具有重要的意义. 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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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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为了缓解埋管区域土壤的热量堆积问题,提出了埋管换热器按内中外、块状、间隔三种分区运行的策略,利用CFD软件建立了10×10的井群换热模型,对地源热泵系统在三种分区与不分区运行策略下运行十年进行数值模拟,分析不同分区运行策略对土壤温度分布和土壤热堆积特性的影响。模拟结果可知:不分区、内中外分区、块状分区、间隔分区四种运行策略下埋管区域的平均温度分别为25.23、23.31、23.06、23.28℃,最高温度分别为40.62、32.77、40.65、38.93℃;分区运行较不分区运行可以有效缓解热堆积作用,埋管区域整体温度较不分区运行时降低了2.00℃左右,内中外分区策略可以显著缓解埋管区域热堆积。 相似文献
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讨论了用于逆变器冷却的水冷单元柜,针对柜内几种散热器和柜内通风结构方案进行了对比分析,探讨了影响水冷单元柜散热性能的因素,总结了提高水冷单元柜散热性能的措施。 相似文献
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Ibrahim Dincer 《国际能源研究杂志》1996,20(7):643-649
This reseach was performed using experimental temperature data and a simple analytical model to estimate the temperature distributions at the centres of cylindrically canned products (diameter/thickness ratio = 4/1) during heat sterilization and cooling under continuous flow conditions for two retort temperatures (115 and 121°C). The recorded experimental temperature data for an individual can for two different retort temperatures were then used to construct the dimensionless experimental centre temperature curves. In order to predict dimensionless centre temperature profiles with a mathematical model, the convection boundary condition (i.e. 0·1 < Bi < 100) in transient heat transfer was considered. The predicted temperature profiles were compared with the experimental centre temperature measurements for two cases—heat sterilization and cooling. The experimental temperature values were in very good agreement with the theoretical predictions. The results of this study show that the present technique is a reasonable tool for estimating in a simple and accurate form the temperature distributions of a cylindrically canned product subject to both heat sterilization and cooling. 相似文献