【作者】 张新宇；

【导师】 王晓纯； 高建岭；

【作者基本信息】 北方工业大学 ， 机械电子工程， 2005， 硕士

【摘要】 土壤源热泵空调系统利用大地作为冷热源,通过中间介质在埋于地下的封闭环路中循环流动,与大地进行热交换,进而由热泵实现对建筑物的供冷或供暖。与传统空调相比,土壤源热泵空调系统利用可再生能源,具有节能和环保的特点。它在欧美已有数十年的历史,近年来在中国受到广泛关注,并已开始得到利用。由于对土壤源热泵系统的核心部件——地下换热器的研究还不够完善,这在很大程度上制约了土壤源热泵的应用。本文即在北京市可持续发展基金的支持下,对地下换热器的传热问题进行研究。由于U型竖直埋管式土壤源热泵具有占地面积小、可用范围广、灵活性较高、恒温效果好、换热效率高、维护费用低等众多优势,已成为目前应用最为广泛的埋管方式,故本文侧重于U型竖直埋管地下换热器的传热研究。 针对已有研究方法存在的问题,本文引入了通用有限元分析软件MSC.Marc对土壤温度场进行研究,可以模拟热泵长期运行工况下土壤温度场瞬态分布情况,并且只需酌情更改计算模型中的各相关参数即可将此方法应用于其他地区,解决了以往研究多针对短期工况,且计算模型缺乏普遍适用性等问题,为地下换热器模型的研究找到了新的途径,从而为进行更深入的分析奠定了基础,使传统方法不易解决的复杂问题模拟成为可能。具体研究过程如下:建立竖直埋管式土壤源热泵埋管周围土壤温度场物理模型和数学模型,并利用有限元软件MSC.Marc对温度场模型进行模拟;通过模拟结果和实测数据的比较,论证了利用MSC.Marc进行土壤温度场模拟的可行性与准确性;在确认方法的可行性与准确性的基础上,针对地下换热器实际工程应用中所关心的问题进行了理论研究,使人对于各种因素对土壤温度场的影响有个直观上的概念,以供进行地下换热器设计时参考;最后结合国际上常用的地下换热器设计方法,将计算模型应用于工程实际,总结出一套可行的地下换热器设计流程。更多还原

【Abstract】 Ground-coupled heat pump (GCHP) air conditioning systems utilize ground soil as a heat source/sink, achieve heat transfer between the ground soil and a working fluid circulating in a closed loop buried in the ground. Compared to other conventional alternatives, the ground-coupled heat pump system makes full use of renewable energy, and boasts the features of protecting the environment and reducing electric power consumption. It has been applied in Europe and American for a few decades. In recent years the technology has been paid attention to also in China, and a few GCHP projects have been completed. However, researches on design of the ground heat exchangers are far from adequate. This situation impedes its application. With the aid of Beijing Sustainable Development Fund, we have been making research of ground heat transfer. As vertical U-Tube ground-coupled heat pumps have become the most widely used heat pumps because of many outstanding advantage it has, such as: fewer area requirement, fewer limits, running steadily, better performance, lower costs on system maintenance etc, the thesis lays emphasis on vertical U-tube heat exchangers.Having noticed that the former research methods have some problems, MSC.Marc, the general finite element analysis software, is used to study the soil thermal field. It can simulate the transient heat transfer under the condition of long-term operating mode, and can be applied to other areas only to change several related parameters. So it has solved some problems that bothering the former researchers, such as the model can only simulate the short-term behavior of ground heat exchangers and has some difficulty to be used to other areas etc. This is a new way to study the model of ground heat exchangers, it lays a foundation for further study, and makes it possible to solve complicated problems which can hardly be simulated by traditional methods. Details of thermal analysis are shown below: Firstly, numerical models were set up to simulate the ground heat transfer around the U-tube heat exchangers; Then MSC.Marc is adopted to make numerical simulation for it; And then comparisons were made between the theoretical predictions and the experimental results, through which we found the results match quite well, this indicated that the method to study the ground heat exchangers is feasible and更多还原