Earth Tube Heat Exchanger Performance Correlation Using Boundary Element Method

ABSTRACT THE boundary integral equation method (BIEM) was developed in this study to analyze the performance of steady state potential type problems. The numerical implementation of BIEM was done for earth tube heat exchangers as an example. Based on the steady state heat conduction equation and a constant temperature boundary condition along the soil-tube interface, an equation for predicting the thermal performance for earth tube systems was developed. The earth tube variables studied included: tube diameter, soil temperature, and ambient air temperature. The location of tubes below the ground level significantly affected the heat exchanger thermal performance. Earth tube exchangers for heating greenhouses during winter months can be economical.