Environmental effects of ground source heat pump system with vegetation on the ground surface

Research on the interactions among Ground Source Heat Pump (GSHP) system, vegetation and microclimate is needed due to exhausted heat from the GSHP system to surrounding environment and ambient temperature reduction by vegetation transpiration. Models in previous study are intended to research the heat transfer underground and to improve the heat transfer efficiency of ground heat exchangers. In addition to these heat transfer models, previous research shows that the performance of a ground heat pump system was found to depend strongly on the moisture content and the soil type, and a number of studies have been conducted to investigate the cooling effect of urban green space using analytical modeling approaches and empirical analysis. The aim of this study is to compare the heat exhausted from GSHP system to the microclimate and the influences of transpiration of vegetation on the surrounding environment in the summer season. In this article, energy balance models of soil and vegetation has been set up to analyze the heat flow among the vertical tubes of a GSHP system, soil, vegetation and the ambient environment. Heat released from GSHP system after long-term operation is predicted on the basis on simulation results. Furthermore, transpiration experiments are conducted to evaluate its cooling effects. The energy influence of the vegetation and GSHP on the environmental atmosphere has been compared. Based on the calculated results and measurement data in Shanghai city (southeast in China), suggestions are given to the application of GSHP system combined with vegetation to balance microclimate.