Thermal Performance of Heat Exchangers for a Rainwater-Ground Source Heat Pump

This paper presents the results of experimental measurements of the performance of two types of heat exchanger-solid bars and heat pipes-for a heat pump designed to make use of rainwater and ground as heat sources/sinks. A refrigerant was circulated through a closed loop of copper pipe to transfer heat between the heat pump and rainwater in a storage tank and the heat exchanger to transfer heat between the stored rainwater and surrounding soil.Tests were conducted under controlled laboratory conditions. Physical and thermal properties of soil such as water content, density, thermal diffusivity, specific heat and thermal conductivity were detemined. Numerical simulations were also carried out for a rainwater storage tank installed under ground for a typical domestic application with different operating conditions of the heat pump.