Performance Characteristics of Vapour Compression Refrigeration System Under Real Transient Conditions

The behavior of performance parameters of a simple vapour compression refrigeration system were studied while its working under transient conditions occurred during cooling of a fixed mass of brine from initial room temperature to sub-zero refrigeration temperature. The effects of different lengths of capillary tube over these characteristics have also been investigated. It was concluded that with the constantly falling temperature over evaporator, refilling of it with more and more liquid refrigerant causes multifold increase in heat transfer coefficient which helps in maintaining refrigeration rate at falling temperature. Larger capillary tube decreases the tendency of refilling of evaporator but offers less ‘evaporator temperature’ effective in lower range of refrigeration temperature. Shorter capillary tube ensures higher COP initially but which deteriorates at a faster rate in lower temperature range. Capillary tube length must be optimized for maximum overall average COP of the system for the complete specified cooling job.