NUMERICAL SIMULATION ON HEAT TRANSFER CHARACTERISTICS OF SOIL AROUND U-TUBE UNDERGROUNDHEAT EXCHANGERS

摘要

Temperature distribution in the soil around the underground heat exchangers are simulated by a two-dimensional model based on the column heat source theory, with the help of user interface tool-pdetool of matlab software. Through single-tube model, temperature distribution around heat exchangers and thermal radius under such conditions were got. In order to find out heat coupling effect among adjacent boreholes and temperature distribution in the soil, multiple boreholes were simulated on the basis of single-tube model, the coupling degree between tubes was got as well, from which , a concept( heat affected public area )is proposed. To eliminate or decrease the heat imbalance of heat emitted to soil in summer and absorbed from the soil in winter, water heater was added to the GSHP system. Experimental results of the hybrid system show the highest EER of the system could rise to 4.