Matching Design And Performance Optimization For R134a Vehicle Air Conditioning System With Internal Heat Exchanger

It is one of the simple and effective methods to improve the performance of the automobile air conditioning by using the internal heat exchanger. Now, the theoretical and experimental research on the internal heat exchanger is concentrated in the CO2 air conditioning system, R134 a is the vast majority of the use of air conditioning refrigerant in China, the research on R134 a air conditioning system with internal heat exchanger is more practical significance. In the matching test of the internal heat exchanger, We find that the internal heat exchanger will have a negative effect on the system. which makes the merit not conspicuous and the system unsafe, The adverse effects of the internal heat exchanger has become a major obstacle in the automotive industry to promote the use of. Under this background, this paper analyzes the adverse effects in R134 a automotive air conditioning system used internal heat exchanger and experimental study of methods averse the adverse effects. The main contents and conclusions are as followings.First, according to thermodynamic theory, the function of the tube length related to subcooling, superheat and the theoretical cooling capacity enhance is derived. Internal heat exchanger of different lengths and ordinary pipe make comparative experiments in air conditioning systems. By analyzing the experimental data, identified four main parameters of the system adversely affected, they were evaporating pressure, condensing pressure, exhaust temperature and oil content obtained empirical equations of them and tube length.Considering the above four parameters affected system expansion valves, condenser air flow and initial oil content. By adjusting the expansion valve, condensing wind speed and oil content, get the effect of parameter changes on the system. Obtained improve method of adverse effects. By fitting the three groups of experimental data, and the experience of correlatio, obtained the theoretical model of parameter adjustment impact on the system.The boundary conditions into the above model, and obtained the matching length of internal heat exchanger and adjustment amount in the system. In the system bench test and vehicle simulation environment experiment validate the air conditioning system cooling performance, In low, medium and high speed conditions the system cooling capacity were improved 330 w, 740 W, 860 W, COP were raised 3.3%, 9.1%, 16%, the evaporating pressure, the condensing pressure, the exhaust temperature and the oil rate all in the normal range. Through the vehicle environment simulation experiments, the heat recovery system to enhance the cooling than 4 ? compared with ordinary pipe, reached the experimental requirements.