共查询到20条相似文献,搜索用时 218 毫秒
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刘俊 《建筑热能通风空调》2011,30(6):75-79
本文基于经典的线源理论和圆柱源理论,求解了土壤源热泵地下换热器的各项热阻。结合热阻概念,建立热平衡方程求解了单位深度换热量。分析了系统运行时间、管内水流速、回填材料导热系数、冬夏季进口水温和岩土类型对热阻和单位深度换热量的影响,为地源热泵系统的优化设计提供参考。 相似文献
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介绍了重庆地区某U型垂直换热器地源热泵实验系统在夏季的供冷情况,提出了对地源热泵系统运行的改进方案,并给出了地下U型垂直换热器的传热模型。 相似文献
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针对影响地埋管换热器热短路现象及换热性能的主要因素(回填材料导热系数和热泵运行方式),建立了U形地埋管换热器的三维非稳态数值模型,通过热响应实验验证了该模型。采用FLUENT软件进行模拟分析,得到不同导热系数土壤条件下地埋管换热器的热短路损失系数和每延米换热量随回填材料导热系数的变化规律,推荐采用导热系数比周围土壤稍大的回填材料。对比了地源热泵连续与间歇两种运行方式,得出当回填材料导热系数小于或等于周围土壤导热系数时,间歇运行对热短路现象基本无影响;当回填材料导热系数大于周围土壤导热系数时,间歇运行可使热短路损失系数降低51.6%~74.5%,每延米换热量提高32.6%~34.0%。 相似文献
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本文利用所建的地源热泵模拟模型对R22地源热泵系统的运行特性的模拟结果进行了分析,探讨了影响地源热泵运行特性的主要因素,并对不同土壤类型、不同回填材料、不同运行方式的地源热泵运行特性进行了模拟分析对比.研究表明,土壤特性对地源热泵的运行特性有重要的影响,回填材料也在一定程度上,制约着地源热泵的运行特性;适当增加埋管长度,或者采用复合地源热泵的系统形式,将有效改善地源热泵系统的循环性能. 相似文献
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Yasuhiro Hamada Hisashi SaitohMakoto Nakamura Hideki KubotaKiyoshi Ochifuji 《Energy and Buildings》2007
This paper describes the field performance of air conditioning with an energy pile system, which was applied to the pile foundations of an actual building for the purpose of reducing the cost of the underground heat exchanger. First, the building for both office and residential use, for which a space heating and cooling system using friction piles was installed, was built in Sapporo in December 2000. Second, three tests were carried out to specify the design of a heat exchanger inside the pile, and a U-tube type underground heat exchanger was adopted from the viewpoint of energy efficiency and installation costs. Long-term space heating operation measurements indicated that the seasonal average temperatures of brine returning from the underground and pile surfaces were 2.4 and 6.7 °C, respectively. The average coefficient of performance for space heating was quite high at 3.9, and the seasonal primary energy reduction rate compared with a typical air conditioning system reached 23.2%. 相似文献
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Energy recovery systems can be used in HVAC to reduce energy consumption by recovering wasted energy from the exhausted air to pre-cool inlet fresh air. In this paper, experimental study of utilizing cooling coil (CC) and cooling coil combined with heat exchanger (CCHE) has been developed. Considering the different climate zones in Iran, the experimental study has been done for the areas with high humidity content. In each case, the effects of air-to-air heat exchanger (HE) on the sensible and latent cooling load are investigated. The analysis gives the applicability of HE in Iran for various operational conditions to obtain air with lower moisture content. In CCHE systems more latent load quota is allocated in cooling coils and lower air humidity ratio can be obtained. Also in the cities with higher dew point depression (difference between dry-bulb and dew point temperature) more humidity reduction is achieved and the difference between latent load quotas of CCHE system is higher than CC system. 相似文献
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The vapour absorption refrigeration system is not so much used commercially because of its low performance. The performance of an absorption refrigeration system is required to make it an efficient alternative of vapour compression refrigeration systems. This paper reviews different research on modification of absorption systems contributing to enhance the performance of absorption refrigeration systems. This study suggests that the performance of absorption refrigeration is improved by using double-effect and semi-generator absorber solution heat exchanger arrangement. The coefficient of performance of absorption refrigeration is also improved by the combination of different refrigeration cycles (hybrid refrigeration cycle) such as compression–absorption and ejector–absorption.Abbreviations: COP: coefficient of performance; GAX: generator absorber solution heat exchanger; ARS: absorption refrigeration system; ECOP: ecological coefficient of performance; CAHP: compression-assisted absorption heat pump 相似文献
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地源热泵系统热短路分析 总被引:1,自引:0,他引:1
主要进行地源热泵系统的热短路实验研究,对河北工程大学120m埋深地源热泵U型埋管实验室进行冬季性能测试,进行多流量工况的测试,流量分别为4t/h、3.5t/h,3 t/h各运行5 d,地下埋管单位井深换热量也会随著流量的减小而减少;埋管中的流量变化和埋管中的换热量的大小对热短路都有影响.通过热短路分析,提出了改进措施. 相似文献
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盘管换热性能受多方面因素影响,在实际运行过程中其换热性能与额定工况性能往往存在偏差。本文以上海地区某一居住建筑为例,建立基于热交换效率的风机盘管换热模型,引入统计学方法从宏观角度分析盘管在换热过程中的分布性规律。实测数据表明,盘管在实际运行中相比额定工况全热量,显热量和潜热量分别下降39.5%,37.9%和44.3%。通过正态性检验发现,该盘管全热量可以看作是均值为1.256、方差为0.208的正态分布,而显热量与潜热量的分布并不具有正态性特征。最后,对提高风量后的盘管换热性能进行模拟,可以发现提升至高档(风量提升28.6%)后,对于相同的室内环境条件下,盘管显热量和全热量可分别提升26.5%,20.9%。 相似文献
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This paper presents an experimental study on the evaluation of thermal response of a spiral coil type GHE (ground heat exchanger). This GHE was installed on partially saturated landfill ground that was composed of silt and clay in the runway area of Incheon International airport. TRT (thermal response test) was conducted for more than 65 hours under continuous operation conditions. Ground thermal conductivity was derived based on line source theory, which has usually been found to be appropriate for line type GHEs such as U, W and 2U types. A reasonable method to derive ground thermal conductivity using the infinite line source theory for a spiral coil type GHE was introduced. Ground thermal conductivity from the TRT using spiral coil type GHE was compared with those from the analytical equivalent model of ground thermal conductivity. 相似文献
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采用自主研发的浅层地下岩土热物性测试平台,通过模拟冬夏季取放热实际运行工况,对不同工况下地源热泵地埋管热交换器的换热能力进行了实际测试,分析了地埋管换热器与周围地下岩土之间的换热状况,确定了该地区地源热泵系统地埋管换热器冬夏季工况下的实际单位延米换热量。同时,根据测试数据推算出了该地区地下岩土的综合导热系数,体积热容等热物性参数,为该地区地源热泵系统的模拟分析以及设计施工提供了依据。 相似文献