The Research On The Thermal Short-circuiting Of Ground Source Heat Pump System

Ground Source Heat Pump is an energy efficient air conditioning system which use the shallow underground geothermal resources (also known as geothermal energy, including groundwater, soil or surface water, etc.) . Compared with traditional air conditioning system, ground source heat pump system use renewable energy, with energy saving and environmental protection. Ground Source Heat Pump in China has been the promotion and application.The important and difficult of the study on Ground source heat pump system is the heat transfer performance of the underground heat exchanger, and the heat transfer between underground heat exchanger and soil is an extremely complex process.There are many factors,one of the most important is a phenomenon called thermal short circuit which inevitably occur between the two pipe. The so-called thermal short circuit, means the U-tube heat interference between the two tubes. This phenomenon reduces the underground heat exchanger in heat transfer efficiency at a certain extent.This paper relies on actual projects, setting up a three-dimensional heat transfer model of underground heat exchanger with insulation pipe created by PHONICS Software .The heat transfer process of underground pipe insulation and non-U insulation in winter for heat condition was simulated by PHONICS software , obtained under the two different flow buried the outlet temperature changes with time.The thermal short circuit phenomenon is proved by the simulation. By comparing the two units of well depth on heat buried with time, and then verify whether the measures can improve the thermal performance of ground source. This research results for the design of heat exchangers buried played a certain reference, with a wide range of practical applications.