DEVELOPMENT AND PERFORMANCE EVALUATION OF DOUBLE EFFECT CONDENSING UNIT (SUBCOOLER

Abstract

Refrigeration systems generally consume large amount of energy for their cooling and freezing applications. Mechanical subcooling is one of the methods available for reducing energy consumption and enhancing the performance of a refrigeration system without increasing the system’s work input. Therefore, the development of a double effect condensing unit vapour compression refrigeration system was carried out in this study and its performance was evaluated. The system is composed of two cycles cascade refrigeration system working with R134a. It consists of a rectangular shape with total storage space of 0.582 m3, made of galvanized mild steel and internally insulated with 0.05 m polystyrene foam. Tests under a wide range operating temperature conditions were carried out on the developed system. Investigations were conducted to check the freezing rate of the main cycle vapour compression refrigeration (VCR) system and dedicated subcooling cycle VCR system for 12 hours at 30 minutes interval. Experimental data were obtained to study the performance of the developed improved VCR system which consists of the main VCR cycle and subcooling VCR cycle over a condensation temperature range of 54 to 57°C and evaporation temperature range of -10 to 30°C. Performance evaluation of the system was characterized in terms of cooling capacity and coefficient of performance (COP). Experimental results showed that the dedicated subcooled system attained a steady evaporating temperature of -9.4oC compared to only -3.9oC observed for the basic system at the same operating hours. This indicates that the dedicated subcooling VCR system has 141% faster cooling rate than the main VCR system. The results also showed that the COP of the subcooling system improved better than that of the main system from 23.8 to 30.4% over an evaporating temperature range of -10 to 30oC. It can be concluded that the use of dedicated subcooling cycle in VCR system is more efficient and suitable for the betterment of thermal system performance