PE피복 STS주름관을 적용한 수열원히트펌프의 성능평가

Abstract

Abstract

The water in a pond or a river is one kind of geothermal energy. Water source heat pump (WSHP) system is becoming more popular in the building which is located near the river or pond. WSHP system extracts heat from a pond or a river and the performance of WSHP system is much higher than that of conventional heating or cooling system. Surface water heat exchanger (SWHE) as a part of WSHP system affects the efficiency of whole system. Thermal performance of SWHE is insufficiency. Because the material of submersible tube in SWHE such as the high density poly ethylene (HDPE) has low thermal conductivity as well as the tube has thicker HDPE. In order to increase the coeffiticent of overall heat transmission (U value) in SWHE 32A polyethylene covered stainless steel corrugated tube (PECCT, STS 0.25㎜, PE 0.5㎜ for anti corrosion) applied to SWHE in the surface water source chilling (SWSC) system in this study. The purpose of this study is the verification of thermal performances about PECCT in SWHE through the comparison of thermal performances of PECCT (32A) and the traditional HDPE tube (32A). U values of two tubes were experimentally obtained by the small SWSC system (1HP), the water chambers in the laboratory. The experiment show that U values of HDPE tube, PECCT were 7.493, 11.144 (W/K) per meter, COP of HDPE tube, PECCT were 1.903, 3.248 at conditions that the natural convection of outer tube and 0.7m/s fluid velocity, respectively. At conditions that the forced convection of outer tube (approximately 0.1m/s outer water velocity) and 0.7m/s fluid velocity, U values of HDPE tube, PECCT were 8.144, 13.747(W/K) per meter, friction factor of HDPE tube, PECCT were 0.024, 0.048, COP of HDPE tube, PECCT were 2.200, 3.485 respectively. Proposed tube in this study has reasonable pressure rating, long term durability. However, since the thickness is so thin, the system may require the chemical agent for protection from inner surface corrosion.