고효율 증기 분리식 2단 팽창 냉동 사이클 성능 특성 연구

Abstract

The objective of this study was to improve the performance of the vapor compression refrigeration cycle comprised of a compressor, condenser, expansion device, and evaporator. In an original refrigeration system, a portion of the liquid refrigerant evaporates after the expansion process. The vaporized refrigerant does not have a role in the refrigeration effect in the evaporator. This study, therefore, aims to improve the energy efficiency by introducing a vapor separation mechanism in a two-stage expansion refrigeration cycle. In other words, the vapor separation process would separate the vapor from mixture beforehand so that higher amounts of liquid refrigerant flow within the evaporator. Results indicated a significant improvement of about 30% more than the existing refrigeration cycle using the new vapor-separated cycle, when a middle expansion pressure of 5 bars is applied in a typical R134a domestic freezer cycle with high pressure conditions of 10.166 barat 40℃ and low pressure conditions of 1.064 bar at -25℃. Moreover, since the mass flow-rate of the liquid phase in the evaporator decreased by about 15%~20% more than the current cycle, evaporator size could be significantly reduced.