| Ground-coupled heat pump (GCHP) air conditioning systems utilize ground soil as a heat source, achieve heat transfer between the ground and a working fluid circulating in a closed loop buried in the ground, and then provide buildings heat and cold. GCHP has received increasing attention at home and abroad because of its significant energy saving and environmental protection benefits. But the research of GCHP in China still in its beginning stage and has no mature design specifications or a summary of operating experience. With the aid of Beijing Sustainable Development Fund, the Finite Element Method of Lines (FEMOL) is first introduced in this paper to analyse thermal field and calculate the underground thermal field of GCHP with FEMOL.A model works of GCHP is completed in this paper and accumulates temperature changes of water in underground pipe with time turning in winter. These datas provide reference for the design of GCHP.This paper first analyzes various of factors that impact heat conduction and then identified the transfer model of this paper by discussed on the transfer model. The paper analyzes the characteristics of the thermal field and its boundary conditions, calculate the analytical solutions use the method of isolating variables so that it can be compare with this paper's results.A a×b unit is used as an example to illustrate the theoretical analysis of FEMOL and gets a group of ordinary differential equations (ODE) and its boundary conditions. Then describe the solve function, operation method of COLSYS and authenticates its accuracy. And the results show that the accuracy of COLSYS completely satisfies request. At last, the paper use COLSYS to calculate the ODEs and its boundary conditions and then compare with the analytical solutions. The comparison shows that FEMOL can be applied to the ground thermal analysis and get high accuracy and a satisfactory answer.The method of the paper is applied to a actual project, and calculate the underground thermal field of ShangYuan apartment. The comparison of the results and measured date shows that the result of FEMOL is closer to the measured data. |
