Heating potential evaluation of earth–air heat exchanger system for winter season

Abstract

Earth–air heat exchanger system can be used effectively to reduce heat energy demand of buildings in cold and dry winter weather conditions. A quasi-steady state, three-dimensional model based on computational fluid dynamics was developed to evaluate the heating potential of earth–air heat exchanger system. The simulation model of earth–air heat exchanger system is developed in computational fluid dynamics platform CFX 12.0. The simulation results obtained from computational fluid dynamics modeling of earth–air heat exchanger were validated by experimental observations taken on experimental setup installed in Bhopal (Central India). A good agreement was observed between simulation results and experimental observations with maximum values of coefficient of correlation and root mean square of percent deviation 0.999 and 2.1%, respectively. The experimental setup of earth–air heat exchanger with polyvinyl chloride pipe of 19.228 m length and 0.1016 m diameter buried at 2 m depth discussed in this article gives the maximum and minimum rises in air temperature of 8.2°C and 6.8°C for air flow velocities of 2 and 5 m/s, respectively. It was seen that the rise in air temperature is faster for the initial length of the pipe and it became moderate for the remaining length. The total hourly heat energy gain or heating potential obtained from experimental setup of earth–air heat exchanger varied from 0.59 to 1.22 MJ h for air flow velocities of 2–5 m/s. The air flow velocity is found to greatly affect the thermal performance of earth–air heat exchanger system.