Study of Electronic Thermostat on Performance & Fuel Economy of Naturally Aspirated Gasoline Engine

In view of global concern for greenhouse gas emissions, need for greener and efficient Engines is increasing. Hence is it imperative that Internal Combustion Engines are improved in terms of efficiency to reduce Greenhouse gas emissions and meet CAFE targets. The cooling system of an ICE plays a major role in a vehicle performance. In this system, the radiator, thermostat, and cooling fan are the main components. Conventional cooling system uses Wax-type thermostat which is activated at specified coolant temperature and maintain same coolant temperature in fully warmed up condition at all engine operating points. Operative temperature selection in Wax-type is trade-off between engine friction & thermal efficiency at lower loads & knocking at higher loads. An electronic thermostat is a good alternative to maintain optimum temperature as per operating point requirement since optimum temperature at different operating points can be different. This paper shows the benefit of maintaining higher coolant temperature at lower-medium loads in Fuel economy by reducing friction and cooling losses. And maintaining lower coolant temperature at full loads to increase maximum Torque by reducing knocking. This paper also highlights the potential to improve Fuel economy by optimizing higher Full Load Torque by Gear Ratio Optimization.