Design of vertical ground heat exchangers based on a layer heat transfer theory

Establishes a mathematic model for threedimensional heat transfer temperature field of vertical ground heat exchanger of ground source heat pump systems. Simulates water temperature distribution in the ground heat exchanger under different conditions and seasons. Presents the layer heat transfer theory, in which the vertical ground heat exchanger and surrounding earth rock are divided into three heat transfer layers—full heat transfer layer, heat transfer layer and none heat transfer layer. Experimentally validates the layer heat transfer theory. Based on the theory, presents the design method of vertical ground heat exchangers including the determination of burial depth and flow rate and insulation of outflow tube.