The Thermostat Characteristics and Its Effect on Low-Flow Engine Cooling System Performance

When the low-flow engine cooling system was developed, besides the addition of a two-pass radiator, another important design change was the replacement of the conventional single valve thermostat with a dual-valve thermostat. This new thermostat was believed to offer better control of coolant temperatures and provide better engine cooling system responses.

The present study is to understand the thermal characters of the dual-valve thermostat and its effect on the performance of a low-flow engine cooling system. By developing a computational thermostat model for use with the VECSS Simulation Code, several computational experiments were conducted to compare the dynamic performance of a low-flow cooling system fitted with different thermostats. The paper contains: a brief description of the dual-valve thermostat and the modeling of its thermal mechanical characteristics; the validation of the thermostat model by comparing the predicted radiator inflow coolant and engine intake air temperatures with manufacturer provided field data; and a study of conventional versus dual-valve thermostat on the performances of a low-flow engine cooling system.