Global climate change is a major concern worldwide and most refrigerants which are being used today are Hydro-fluorocarbon (HFC), which are potent green house gases. With the rising popularity of electric vehicles, there has been an increased demand for effective and efficient cooling system, not only for cabin cooling for bus but for battery pack Thermal Management Systems also. This has led to an increase in the refrigerant amount and it is even more in case of commercial electric vehicle.
Alternate refrigerant with low global warming potential like R1234yf (GWP = 4), Co2 (GWP = 1), R- 152a (GWP = 124) emerged to cater this challenge; But due to their high cost, risk regarding flammability and relative performance, some researchers found secondary loop cooling system as the next possible solution. In secondary loop cooling system Water-Ethylene glycol mixture circulate inside the vehicle cabin and exchange heat with refrigerant loop, which primarily circulate in small loop outside the cabin. These systems reduced the refrigerant quantity and provide versatile control but due to concern about extra plumbing issues, higher cost and need for optimized control system; it has not gain much interest. With projected increase in commercial electric vehicle market, feasibility of secondary loop cooling system is analyzed. In present study a comparative analysis of a secondary loop cooling systems with respect to conventional refrigeration system for a commercial electric vehicle is being done. A full scale model of Secondary loop cooling system having water-Ethylene glycol mixture is developed for a Electric bus. The model has two circuits: a primary small refrigerant circuit and a secondary coolant circuit for battery and cabin cooling, both controlled by a smart drive. Performance parameters like system cooling capacity and Coefficient of performance is measured and compared with conventional system. This study also involve comparative analysis of Conventional cooling system and Secondary loop cooling system when battery cooling is integrated.