Experimental Study on the Impact of Two-Pipe and Four-Pipe Series-Mode Layout on the Heat Transfer in Thermal Response Test for Geothermal Heat Pump Project in Qanavat, Iran

Abstract

One of the effective parameters in calculating the coil length in geothermal heat pump systems is the value of soil thermal conductivity which can be obtained through different methods. This can greatly affect the excavation and coil installation process and consequently the total cost of the project. In case the coil length is reduced, initial cost decreases as the amount of excavation declines and helps the project become economically justified. It can also be possible to increase heat rejection or heat absorption in ground loop by rising thermal conductivity with various configurations. In normal conditions, in each borehole, a U-shaped polyethylene pipe is laid and thermal response test is carried out. But, it is also possible to do the same test with a pair of U-shaped polyethylene pipes. In other words, in this scenario, two U-shaped polyethylene pipes can be used in parallel or series in one borehole. In this paper, the experimental results of thermal response test for normal single pair configuration and two pairs of U-shaped polyethylene pipes in series are presented. The project is located in Qanavat, Iran and the results indicated thermal conductivity improvement in series layout.