Studies on the performance of a mobile air conditioning system using hfo1234yf as an alternative for hfc134a

Abstract

Air conditioning (AC) systems in passenger vehicles are becoming increasingly popular and around the world, almost 100% of passenger cars are employed with ACs consuming 12% 17% of the engine s total energy. In the mobile air conditioning (MAC) sector, HFC-134a has evolved as a permanent replacement for CFC-12 and is being used for the past few decades. As global warming has become increasingly significant, Kigali Amendment to Montreal Protocol has been planned to ban the usage of HFC-134a in new systems by 2028 in India due to its high global warming potential (GWP) of 1430. In Europe, the MAC manufacturers fixed the maximum permissible limit of GWP in alternatives as 150 due to their fluorinated greenhouse gas regulation. Therefore it is necessary to select new alternative refrigerants having low GWP less than 150 to be a substitute for HFC-134a in Indian MAC sector. The environmental protection agency (EPA) has listed HFO-1234yf as a significant alternate refrigerant for air conditioners in passenger cars and light-duty truck. The HFO-1234yf has thermo-physical properties similar to those of HFC-134a but with a low GWP of 4 and mild flammability with A2L classification in ASHRAE standards. However, the performance of HFO-1234yf was poorer than that of HFC-134a in retrofit conditions. Hence, it is significant in the present context to study the possibilities of enhancing performance of the MAC system with low GWP HFO-1234yf refrigerant. In the present work, the charge optimisation of MAC system was carried out for two different compressor speeds. The experimental results showed that the exergy based optimisation as highly reliable and consistently yielding a single optimum charge irrespective of the compressor speed, while newline