EXPERIMENTAL ANALYSIS OF MICROCHANNEL CONDENSER USING R134a AND DROP IN SUBSTITUTE HYDROCARBON MIXTURE OF R290 AND R600a

Microchannel condensers are widely used in automobile and household air conditioners with R134a as a refrigerant. In order to reduce the global warming potential as well as the refrigerant charge, hydrocarbon mixture of R290 and R600a (50:50 % by mass) was used as a drop in substitute to R134a in the vapour compression refrigeration system. Versatile vapour compression refrigeration system of 1 ton of refrigeration capacity was designed, developed and fabricated for testing different refrigerants. Various parameters such as ambient temperature in the condenser cabin, different condensation and evaporation temperatures, different mass flow rates of refrigerant and air can be controlled precisely in the test rig. Experiments were performed using R134a and hydrocarbon mixture of R290 and R600a (50:50 % by mass) for condensation temperature of 44 degrees C and evaporation temperature ranging from -15 to 15 degrees C. Refrigerant charge was reduced by 45 % with the hydrocarbon mixture of R290 and R600a (50: 50 % by mass) over R134a. Performance parameters such as compressor power consumption increases by 13.3 %, coefficient of performance reduced by 43 %, refrigeration capacity increased by 140.8 %, condenser capacity increased by 185.4 % and the product of overall heat transfer coefficient and surface area of condenser was increased by 243.7 % by using hydrocarbon mixture of R290 and R600a (50:50 % by mass) over R134a with the microchannel condenser at condensation temperature of 44 degrees C and evaporation temperature of 0 degrees C. It is suggested to use an environmental friendly refrigerant, hydrocarbon mixture of R290 and R600a (50: 50 % by mass) as a drop in substitute to the conventional refrigerant R134a in the automobile, household air conditioning and refrigeration systems.