CFD Analysis of Earth Heat Exchanger with Air as a Cooling Medium

Abstract

An earth air tube heat exchanger (EATHE) uses the thermal energy of the ground for the air cooling in summer and air heating in winter due to the temperature difference between the air and underground surface. With the help of EATHE we can reduce the energy consumption required for space heating or cooling. However, for determining the surface heat convection, due to lack of available methods it is difficult to make accurate energy simulation and design. Research of EATHE was carried out at beginning as a field investigation. But now software simulation is used for measurement of heat transfer. It requires complex dimensioning process, such a system which involves optimization of numerous parameters such as the diameter, air flow rate depth, tube length and condensation in the meantime have to be considered. ANSYS Software will be used for simulation & modeling, under ANSYS software will use computational fluid dynamics (CFD fluent) workbench as simulation analysis the pipe of 45 m length, 0.004 m thickness and 0.08 m diameter. Air velocity considered 1 m/s and 5 m depth of pipe from the earth ground. The temperature value considered for inlet for a days in June (2016) to May (2017) according the climate of Bhopal, MP, which have been declared by the government of Madhya Pradesh. Using the CFD model, heat convection intensity to various design parameters can be analyzed and the parameters were identified as being influential. Based on the cases, a large number of CFD simulations may be performed to find mathematical relations between the local heat convection rate and the design parameters. It is likely to be observed at increasing velocity that rate of heat transfer, mid temperature, outlet temperature varies in summer and winter.