EFFECT OF LIQUID-VAPOR SEPARATION ON THE THERMAL-HYDRAULIC PERFORMANCE OF AN AIR-COOLED CONDENSER

Abstract

This work characterizes the use of liquid-vapor separation inside air-cooled condensers and its effect on thermal-hydraulic performance. A series of 3 mm inner diameter U-tubes were installed in the condenser for the liquid-vapor separation with 6 mm inner diameter and 215 mm long-finned condenser tubes. R134a was used as the working fluid. During operation, condensed R134a was separated by the liquid-vapor separation device to significantly improve the heat transfer compared to that of a serpentine condenser without liquid-vapor separation. In addition, fewer tubes were required inside the air-cooled condenser due to its high heat transfer rates, which indicated a potential for reducing the condenser size. This study investigated the key factors affecting the liquid-vapor separation process, such as the number of liquid-vapor separation devices, the wind velocity, and the total mass flow rate. The results indicated that in-tube pressure drop is the dominant parameter affecting separation efficiency. This liquid-vapor separation condenser design had better thermal-hydraulic performance than a serpentine condenser due to the enhanced heat transfer. Adding an additional liquid-vapor separation structure changed the separation conditions of the previous separation structure and made the condensation heat transfer more uniform.