Heat Transfer Characteristics Analysis Of Heavy-duty Diesel Engine Preheating System

With the development of modern automobile industry, cars become an everydayessential transport slowly. Engineering is a very important part of the cars. Heavy-duty dieselengine becomes more and more important. The advantages of the diesel engine are highpower and low fuel consumption. But there are still some problems. The most importantissue is diesel engine could not start properly in the cold regions of northern China. Enginepreheating system is proposed in order to solve this problem to make diesel enginesoperation more reliable in winter.Content of this paper is the numerical simulation method for a heavy-duty diesel enginepreheating system. We study heat transfer characteristics of heavy-duty diesel enginepreheating system and summarized effect of the coolant flow characteristics for thepreheating system heat transfer characteristics. Simulate the process of preheating systemwarm up the engine at low temperatures. Get the warm up time and temperature variation ofheavy duty diesel.The paper build three-dimensional models of the preheating system first, afterappropriate extraction simplified physical model of the preheating system and repair of thephysical model, guide preheating system model to grid software for discrete process obtainhybrid grids. Import the grid into the CFD simulation software to get the distribution of thecoolant velocity vector, the distribution of heat transfer coefficient, pressure distribution,coolant mass flow distribution and temperature distribution. In the original model, preheatthe wall of the head water jacket to354.47K, the wall of the cylinder water jacket to353.59K need530s. According to the calculation results, there are many areas to improve forthe structures of the preheating system. Pose three optimization programs to improve theefficiency of preheating system. Optimal scenario, after500s preheating, head water jacketaverage temperature rises from253K to357.75K, the average temperature of the cylinderwater jacket increased from253K to356.91K. In order to study the whole process of heat transfer characteristics the when the enginecold start, the paper build model of the fuel preheater, diesel engine models and the model ofcoolant flow control mechanism, and then integrated the three part into the overall model ofpreheating system. Its flow characteristics and heat transfer characteristics were analyzed.After simulation analysis, obtained air intake mass flow rate variation characteristic curveand the wall of the engine water jacket temperature variation characteristic curve. Thesecurves are in line with engine preheating system operation rules. The results were comparedwith the three dimensional simulation are consistent.