Monday August 26, 2019 from 15:30 to 17:10
Thermal performance of underground heat exchanger for ground source heat pump that uses direct expansion method
Ryosuke OKAZAWA1, Tetsuaki TAKADA2, Syuhei ISHIGURO1.
1University of Yamanashi Graduate School, Kofu, Japan; 2University of Yamanashi, Graduate School of Engineering, Kofu, Japan
The specification of the underground heat exchanger used for the ground source heat pump that uses direct expansion method could not be established so far since the refrigerant flowing in the underground heat exchanger is a gas-liquid two-phase flow accompanying evaporation and condensation and its behavior is also complicated. Therefore, an experiment was conducted using a U-shaped heat exchanger in which one 3/8-inch copper tube and multiple 1/4-inch copper tubes were connected at the bottom as a heat-collecting tube. In this experiment, the parallel underground heat exchanger were used. We introduced this underground heat exchanger into the air conditioner used for actual agricultural vinyl house, and describe the results of the demonstration test. The COP in the cooling operation was about 4.0 and in the heating operation it was about 3.5, and the primary energy consumption reduction rate compared with the conventional system was 20% and 43% respectively.