Comparative CFD analysis of helical shaped earth air pipe heat exchanger using water tube as a thermal reservoir using different pipe materials

Common configuration of EAPHE system usually consider single or U shaped configuration, which requires large installation area and are not suitable for installation under small home or office setup. This major drawback can be overcome by using helical shaped air pipe, which reduces installation area up to 60%. Performance of EAPHE deteriorates after long run due to thermal saturation in the soil near to pipe surface. In this paper problem of thermal saturation of soil is attempted by proposing water pipe of three different pipe materials. Water pipe act as thermal reservoir to absorb heat from surrounded soil and maintains constant heat transfer after 24 hours of long run. Thermal performance of Earth Air Pipe Heat Exchanger (EAPHE) has been investigated under four different type of model developed using helical air pipe and comparison were made in terms of temperature drop, soil temperature at 0.05m and 0.25 m from pipe, change in water temperature, COP and effectiveness of the system for the continuous 72hours of run.