| The thermal control of automotive power supply system and air conditioningsystem is one of the core problems of vehicle thermal management because of thedouble standard, namely, high dynamic and high comfort, required by designers andusers in the vehicle developing field currently. The previous researches about theunderhood multi-thermal system analyze the thermal flow and heat transfer in amacroscopic view, while they overlook the interaction of the two critical parts, theradiator of engine cooling system and the condenser of air conditioning system, whichbelong to separate systems. Actually, however, the radiator influences the vehicledynamic and the condenser has impact on the vehicle comfort. Therefore, it is moreessential to couple air conditioning system when analyzing the underhoodaerodynamic cooling system.This paper suggests principles and means about the various parts in the systemwhile using CFD simulation through the conclusion of vehicle underhoodmulti-thermal systems and the contrast of different research methods; also analyzesthe aerodynamic cooling process inside the underhood and makes recommendationabout the recirculation phenomenon; moreover, gives the measurement and analysismethods of the radiator of engine cooling system and the condenser of airconditioning system; finally, makes the coupling analysis of the radiator and thecondenser which emphasizes the influence on geometric correlation between theradiator and the condenser.This paper concludes the relative technology and research about vehicle thermalmanagement which stresses the development and progress in the analysis ofunderhood thermal flow. Furthermore, it states some analysis methods, such as modeling, numerical simulation, and computing method, including one-dimensional(1D) analysis, three-dimensional (3D) analysis and lumped parameter (LM) analysis.Meanwhile, though the research and discuss about the basic model of CFD, this papergives further supports about the advanced analysis of vehicle thermal management.It’s essential to simplify the actual structure of the actual underhood, andoptimize the mesh generation to ensure the underhood actual structure and thecalculation accuracy. This paper uses porous media model to simulate resistantcharacters and uses NTU (number of transfer units) model of heat-exchanger model tosimulate thermal characters on the radiator and the condenser, and also cooling fanapplies MRF model to simulate the rotation effect of the power supply. Meanwhile, ituses the specified the heat flux or volumetric heat source to simulate the other partslike engine and exhaust pipe in the underhood. At last, the simulation results arecompared with the experimental data in order to verify the accuracy of the model.This paper analyzes the underhood thermal character and flow exchanges in idlespeed, climbing, and high speed situations. The result shows that it works worst in theidle speed situation which leads to lots of recirculation phenomenon in front of theradiator and condenser, Therefore, in order to reach the design requirements, addingguide plate and seal plate to weak the recirculation phenomenon can effectivelycontrol such problem and decline the temperature on the specified face. While itworks better in the high speed and climbing situation.This paper analyzes the radiator of underhood cooling system coupling thecondenser of air conditioning system, thereby stating radiator measurement index,namely, cooling constant index K and condenser measurement index, namely, averagetemperature on the condenser exit. Furthermore, these two indices are used to measurethe work conditions of radiator and condenser in different situations including idlespeed, climbing, and high speed and also measure vehicle aerodynamic characters andinfluences on the coupling systems when condenser changes its locations longitudinaland transversal relative to the radiator. Pointing out the significant influence onunderhood cooling process considering the coupling effect of the radiator and condenser. |
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