The Investigation On Match And Design Fo Commercial Vehicle Cooling Module

Due to the enhancement of engine power density and requirements of energy-saving and emission reduction, more strict requirements have been placed on the match and design of vehicle cooling system. In commercial vehicle’s engine compartment, the heat transfer performance is directly influenced by the match of cooling fan and heat exchanger module, and other parts’spatial arrangement. Therefore, it is necessary to invest the underhood parts’flow and heat transfer characteristics and there effects on cooling system performance. It is the key to the match design and optimization of vehicle cooling system.Based on the theories of fluid dynamics and heat transfer, this dissertation completed the research on the main factors of the flow of engine compartment and heat transfer performance using kinds of experiment methods. The results could be combined to numerical calculation method to provide a guidance on the match design of commercial vehicle cooling module. The main contents are as follows:The synergistic optimization analysis of heat exchanger module. Research was complet-ed using heat exchanger wind tunnel test platform on effects and variation regulation of different installation on the flow and heat transfer performance of heat exchangers. The field synergy principle could be used to guide the optimized placement of heat exchanger module in engine compartment.The air flow non-uniform distribution analysis of cooling module. The testing platform of commercial vehicle cooling module was established to analyze the air flow non-uniform distribution of heat exchanger with typical fan and shroud. Porous medium model and ε-NTU method was used to analyze the effect of flow maldistribution on heat exchanger’s pressure drop and heat dissipation. And a measurement technology on cooling air was researched on the testing system.Underhood flow and heat transfer characteristics experiment research. The road test technology and method of commercial vehicle’s thermal management system was developed, and the system was established to research a typical passenger car’s underhood flow and heat transfer performance and also its influence factor of vehicle grille parameters. The research on match and design of commercial vehicle cooling module. Based on the research mathods and results of heat exchanger module wind tunnel test, cooling module experiment, vehicle thermal management system road test and numerical simulation, the cooling module’s match and design methodology and software was developed. The match accuracy was finally verified by the vehicle road testing.The following conclusions were achieved through the researched mentioned above:As for the inducing cooling module with series placement, the flow path and homogeneity of cooling air had main effects on flow resistance, and the lengthways relative position of radiators could have certain effects on the performance of backward radiators. Hence, the projection area of front component on radiator’s cover should be reduced, and the distance between radiators should be reasonably selected, also the encapsulation should be reduced, thus decreasing the pressure drop of the cooling air flow. The uniform distribution of temperature difference field of the heat transfer fluids could effectively improve the radiator’s performance.The cooling air flowing through radiator module was influenced by cooling fan and shroud to show non-uniform distribution. And the non-uniform distribution would become even more obvious with the rise of fan speed. The non-uniform coefficient on the windward area of radiators would increase with the rise of Reynolds number at low range. The experiment relevance equation of radiator f factor has certain prediction accuracy on radiators module, however, the effects caused by the non-uniform distribution of cooling air should be considered. Compared with uniform flow, the analysis based on Porous medium model and ε-NTU method showed that the non-uniform flow of the system would lead to an increase of flow resistance and a decrease of heat transfer efficiency, and it is identical with the test result.Influenced by the different flow perfprmance of grille, radiator, fan and kinds of air duct parts, the underhood air flow characteristic is complicated. With the rise of fan speed, the flow velocity of the system increased, and the number of resistance and its proportion would have obvious variation. The blade parameters of intake grille could have evident effect on the system flow resistance and vehicle heat dissipation so that the structure parameters should be reasonably designed during the system match and optimization.Heat exchanger module wind tunnel test, cooling module experiment, vehicle thermal management system road test and numerical simulation are different approaches to reasarch vehicle cooling system. The match and design method according to the investigation results of this dissertation takes full advantage of numerical caculation and test technology. The flexible application of this method could improve the system design accuracy effectively.