In this paper, a new method for determining the optimized dimensions of a ground source heat pump system (GSHPS) heat exchanger is presented. Using the GSHPS is one of the ways for utilization of infinite, clean and renewable energies in the environment. In recent years, due to limitation of physical space for installing the heat exchangers and avoiding the environmental effects on heat exchanger operation, vertical GSHP systems are used more than the other ones. Determination of optimum heat exchanger size is one of the most important parameters in the optimization of the heat exchanger design. In this study, optimum length and diameter for the heat exchanger is determined for different mass flows by using the second law of thermodynamics. The optimal length and diameter minimize entropy generation and therefore result in increased efficiency of the heat pump.

• An initial version of this pa per was published in May of 2004 in the proceedings of Second International Applied Thermodynamics Conference, Istanbul, Turkey.