Abstract
Shallow geothermal resources can be used as both heat source in winter and heat sink in summer. In order to utilize shallow geothermal energy, U-tube downhole heat exchanger is used as the most common method. Because a U-tube downhole heat exchanger has advantage that is the simplicity of construction and cost effective. However, a U-tube downhole heat exchanger has disadvantage that is difficult to increase heat transfer area. Therefore, a downhole heat exchanger with multi-pipe which has larger heat transfer area has been invented. The objective of the present study is to reveal heat extraction characteristics of a downhole heat exchanger with multi-pipe by numerical simulation.
