2017 年 34 巻 4 号 p. 473-
This paper presents the numerical investigation of optimum analysis of slinky horizontal ground heat exchanger (GHE) consists of copper tube loops. The loops were placed in a horizontal plane. Copper tube of which inner diameter is 14.6 mm and outer surface is protected with a thin coating of low density polyethylene was selected as GHE material. Aiming to improve the thermal performance of slinky GHE, the uniform distribution of slinky loops were modified by a geometric sequence such that gradually decreasing the loop pitch interval from starting loop to end loop. A comprehensive experimental investigation was carried out to validate the present numerical model. The numerical simulations were carried out with the CFD ANSYS FLUENT software package. In this study, diameter of slinky loop, number of loop and trench length was fixed as 1 m, 7 and 7 m respectively. The thermal performance improvements were investigated on the basis of effect of different loop pitch arrangement of slinky GHE. The comparative temperature distribution around GHE also being discussed to illustrate the heat exchange improvement mechanisms. The operating water flow rate was 4 L/min and entering water temperature was 27 °C. The computational results indicate that the modified arrangement of slinky GHE loops is a promising for the performance improvement. Under the present operating conditions and geometric parameters considered, the modified arrangement of slinky GHE loops offers maximum 22.2% higher heat exchange compared with uniform distribution of loops of slinky GHE within 7 days of continuous operation.
