Optimizing Cooling Fan Power Consumption for Improving Diesel Engine Fuel Efficiency Using CFD Technique

摘要

Fan cooling system of an air-cooled diesel engine is optimized using 3D CFD numerical simulation approach. The main objective of this article is to increase engine fuel efficiency by reducing fan power consumption. It is achieved by optimizing airflow rates and flow distribution over the engine surfaces to keep the maximum temperature of engine oil and engine surfaces well within the lubrication and material limit, respectively, at the expense of lower fan power. Based on basic fan laws, a bigger fan consumes lesser power for the same airflow rate as compared to a smaller fan, provided both fans have similar efficiency. Flow analysis is also conducted with the engine head and block modeled as solid medium and fan cooling system as fluid domain. Reynolds-averaged Navier-Stokes turbulence (RANS) equations were solved to get the flow field inside the cooling system and on the engine liner fins. The Moving Reference Frame approach was used for simulating the rotation of a fan. Cowl geometry was modified for providing better guidance to flow over engine surfaces and to get maximum utilization of cooling capacity of flowing air. Basic fan parameters like diameter, blade shape, and number of blades were altered to increase the flow rate and reduce fan power consumption. Engine surface temperature is compared between existing and recommended design modified on actual engine test bed. The final recommended design leads to a 3% improvement in engine fuel efficiency, i.e., engine fan power consumption reduction. It is achieved with comparable engine surface temperature.