Thermal Analysis Of Ground Heat Exchangers For Ground-Coupled Heat Pump Systems

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...