New approach for analysis of ground-coil design for applied heat pump systems

The operation of a single coil buried in moisture-saturated ground is described in detail mathematically. The mathematical model includes the effects of coil cyclic operation and soil moisture freezing round the coil. The effect of coil fluid properties and flow characteristics, generally ignored by most of the traditional analytical methods, are also included in the analysis. A computer code based on the model has been completed and partially validated by the field experimental results. A parametric study indicates that the fluid inlet temperature, coil size and material, fluid flow Reynolds number, and schedule of coil cyclic operation are important factors in determining ground coil performance. This computer code can be used for heat pump ground coil design if heating load is predominant.