A novel rainwater-ground source heat pump - Measurement and simulation

This paper presents the results of experimental measurement and numerical simulation of the performance of a heat pump system designed to make use of rainwater and ground as heat sources/sinks. The system was tested under laboratory conditions. A refrigerant was circulated through a closed loop heat exchanger to transfer heat between the heat pump and rainwater in a storage tank and another heat exchanger made of solid bars or heat pipes to transfer heat between the stored rainwater and surrounding soil. Physical and thermal properties of soil such as water content, density, specific heat, thermal diffusivity and thermal conductivity were determined. Numerical simulations were also carried out for a rainwater storage tank installed under ground for domestic application of the heat pump with different operating modes, heating loads and the sizes and types of heat exchanger.