Study On The Cooling-performance Of Automobile Conditioning System Based On Environmental Simulation Test

By the end of2011, china has occupied the first place of the globalautomobile production and sales for many years. Automobiles have played animportant role in our life. The air conditioning system in cars is devotedas a set of devices which used to cool, heat, interchange or purify the interiorair of a car. The system provides comfortable environment for the passengersand helps drivers to release fatigue strength so as to ensure the safety ofdriving. The performance of air conditioner influences a lot the comfort andeconomy of vehicles. The car conditioner, which tends to be electrified,intelligential, miniaturized, light-weighted and environment-protected, willbecome the developing tendency of this major.Customers have increasingly paid more attention on air conditioner of cars;however, there has no a complete set of evaluation method for the performanceof the automobile air conditioning system in China. Some research institutionsstill focus on inducing and studying foreign advanced technologies and thendo some nationalized work. The main method is the comparison of performanceon bench test and original imported parts. Since the performance of vehicleair conditioning system could be influenced by the multi-factors such ascomplicated driving conditions, changeable environment and insulationstructure of the car body and so on. Accurately, the heat load under differenttemperature and driving conditions cannot be available through theoreticalcalculation and which also can not provide strict data supporting the designand improvement of vehicle air conditioning system. Therefore, it is generallyconsidered the automobile simulation test is the most scientific andpersuasive verifying method. Meanwhile, environmental simulation test resultsalso show the similarities and differences among CFD and other theoretical analysis. This will improve the accuracy of CFD theoretical calculation ofconditioning system. Since domestic motor-Dom is weak on these aspectsdiscussed above, automobile industry standardization，《the test method onthe cooling performance of automobile air conditioners》(GB/T658-2000), canonly offer the procedures of test but evaluation criteria is not involved.In addition, the laboratory for environmental simulation test would cost ahuge amount of money and there is a small number of such kind of laboratoryin China. Few initial data accumulation and other factors lead to less accurateand objective evaluation to the refrigeration level of automobile airconditioners.In this dissertation, based on the experiments organized in theenvironmental simulation laboratory of TJFAW, it has been introduced thespecifications, testing project, methods and procedures individually. In thefollowing chapters, the general operational principle of vehicle airconditioning system and the structures and functions of some key components(such as: compressor, condenser, evaporator and expansion valve) on the systemhave briefly introduced. Starting from the basic working principle of systemkey components, the important specifications and control points influencingconditioning system functionalities can be achieved after theoreticalanalysis. After that, the performance of conditioning system on automobilescan be improved through the modification of these key parameters and controlpoints.The whole dissertation has summarized several key factors impactingperformance of air conditioning system, including: the performance ofheat-interchange of condenser with investigating the performance of condenserand condenser fan separately, air distribution around condenser, generalmechanical arrangement of cooling system (heat dissipater, condenser, fan,intercooler), the performance of heat-interchange of evaporator, type ofcompressor, the amount of lubricant filled in condenser, aperture of expansionvalve, the amount of refrigerant added and water-heating valve and so on. Each design alternation on these aspects will be experienced on each different kindof productive vehicles of TJFAW. Through the comparison of environmentalsimulation test, the improving effect caused by each design alternation willbe quantized finally.According to discussed each result from each design alternation with theconsideration of the inheritance of other components and the cost of mould,some types of cars will be selected to be installed the new design alternations.Eventually, the performance of air conditioning system of those changed carsis improved evidentially. By means of the comparisons among different coolingreports from different competitive models, which had distinguishing price andmanufactures, TJFAW has already made the evaluation standardization of coolingfunctionality which will be used as manufacturer’s standard of new productin the future.When we discussed about the cooling performance of air conditioning system,it is inevitable that comfortbility and reliability of conditioning systemshould also come to the attention. For example, the performance of heat-cuttingon air conditioner group case should be considered during the process of design.The advantage of environmental simulation laboratory is to offer theexperiments repeatability, which means the same condition of environment canbe available during a whole day, so that we can find, improve and verify theproblem that appeared in the product development on time.