Heat transfer efficiency of U-shape buried pipes under variable inlet water temperature conditions

According to the varied characteristics of heat transfer efficiency coefficient under the variable inlet water temperature condition of U-shape pipes, decomposes the coefficient into the parameter product of the biggest heat transfer temperature difference ratio of buried pipes (φ) and the outlet temperature difference ratio of heat pump units (σ). Analyses the effect of building load, buried pipe flow rate and unit performance on the heat transfer efficiency of buried pipes by using the three-dimensional heat transfer model of U-shape buried pipes based on the multi-pole theory, and provides technical support for the optimization design of ground-source heat pump systems.