A Model Predictive Approach to Avoid Coolant After-Boiling in ICE

The after-boiling phenomenon in internal combustion engines can occur when the engine is suddenly switched-off after a period of prolonged high-load operation. In this case, the coolant flow rate stops while the engine wall temperature is quite high; therefore, some evaporation occurs, pressure in the cooling circuit increases and part of the coolant is lost through the radiator relief valve. The control of the coolant flow rate by means of an electric pump instead of the standard belt driven one offers the possibility of overcoming this issue. In the present paper, a model-based control of the coolant flow rate is proposed in conjunction with the adoption of an electric pump in the engine cooling system. Experimental tests and simulations have been carried out starting from high speed-high load engine operation; the engine was then brought to idle and, shortly after, switched-off. A comparison with the adoption of the standard belt-driven pump in the cooling system lay-out is presented in order to evaluate the effectiveness of the proposed approach.