| Abstract:In order to further enhance the heat transfer capacity of cylinder head bridge zone of diesel engines, a nano coolant atomizing impingement cooling was proposed. To this end, the effect of atomizing impingement of nano coolant on the heat transfer efficiency of cylinder head bridge zone and the influence of different cooling methods on the diesel engine performance were studied by using computer simulation, high speed photography and integrated bench test system. Results show that the atomizing impingement can achieve efficient cooling of the cylinder head zone and have good temperature uniformity with the maximum temperature difference of less than 6℃ .This is because the surface heat transfer in the bridge zone is dominated by the nucleate boiling of nano coolant, and the atomizing impingement cooling can increase the cylinder head intake air mass flow rate by 9.7% compared with the traditional cooling methods. This allows to have lower NOx and smoke emissions at medium and high speeds with the reduction of HC and CO emissions at low and medium speeds. |