Abstract
In this article, two model order reduction (MOR) methods of Krylov subspace and Laguerre orthogonal polynomials were employed to the numerical simulation of heat transfer characteristics of ground heat exchangers and surrounding ground. The results show that the relative errors between the direct solution and two MOR methods are less than 0.1% under more than certain orders. Considering both the relative errors and time consumptions, for two MOR methods, it is workable to take about 1% of the original system order as the reduced system order. The larger the nodes of space and time, the more obvious the efficiency of two MOR methods.