Analysis of block and cylinder head separate cooling system

Reduction in warm up time of engine reduces fuel consumption and emissions. The hot spots of IC engine are near the exhaust valves and between the cylinders space which need the maximum value of cooling. Coolant at inlet of the block, having a temperature lower than the cylinder head. As a result, the block cooling is more than necessary value to ensure that maximum temperature in the cylinder head is lower that critical value. Reduction in coolant flow rate is associated with block temperature rise, reduction of brake specific fuel consumption and HC and CO emissions. On the other hand, increasing the cylinder head temperature causes problems such as an increase in the production of NOx. One method to solve this problem, is separate cooling of block and cylinder head. In this method, the coolant at the outlet the pump, is divided into two separate paths one for the block and one for cylinder head, and thus, the flow rate which required for cooling each part must be set separately. In this study, to calculate the warm up time, the cooling circuit of national engine has been modeled. To validate, the numerical results of pressure loss of coolant in the engine water jacket, radiator flow rate and warm up time have been compared with the results of the cooling test. At last, the influence of separation of block and cylinder head cooling circuit of engine on warm up time has been studied. Results show 15 percent reduction in warm-up time.