Operating Simulation And Fault Analysis On AC Refrigeration System Of EMU

The appearance of EMU has brought great convenient to people’s daily life. It has been widely used and developed because of its speed, safety and comfort in many countries and regions. With the improvement of living standards, people have higher requirement for the comfort of the EMU. While the air conditioning and refrigeration system of EMU is important equipment for providing a comfortable indoor environment in summer. It is beneficial to improve the EMU’s competitiveness against the air plane and the automobile and to stimulate the development of EMU if the comfort of passenger compartment has been guaranteed. Consequently, it is of vital importance to study the operating conditions and the faults of EMU.Taking a certain type of air conditioning and refrigeration system of currently running EMU that has one air conditioning unit in its cab air conditioning and refrigeration system and two air conditioning units (each includes two Independent refrigeration cycles) in passenger compartment as research target, this thesis analyzed the refrigeration mechanism of the system and the thermal performance of the refrigeration cycle, and also performed a quantitative analysis about the air conditioning cooling load of the passenger compartment.Meanwhile, this thesis analyzed the working mechanism of several main parts of the system such as compressor, condenser, evaporator and throttling set, and built models of every part according to AMESim software and did a simulation analysis. Then based on these models, the thesis built cab and passenger compartment air conditioning and refrigeration system models respectively, and conducted a simulation analysis about several kinds of running state under different running speed.Based on the above models, this thesis further simulat analyzed the influence to the performance of the air conditioning and refrigeration system if the air and main components parameters changed. It also compared the performance feature of the system under different kinds of compressor speed modes and concluded its advantages relative to fixed speed modes. Through the establishment of wet air mixture model, it did a stimulation analysis about the parameter change of the system when add inlet air to the evaporator. In combination with the refrigeration system model, it analyzed the influence of adding fresh air volume to the performance of the system.As for the stimulation analysis of the faults, this thesis stimulated the running state of the air conditioning and refrigeration system of EMU under the circumstance of refrigerant leakage, and uneven distribution of wind and air volume deficiency caused by the blockage of heat exchanger and air filter screen. Then analyzed the refrigeration system faults may result from these circumstances. Aiming at faults caused by blockage of heat exchanger and air filter screen, this thesis analyzed the importance and method of maintaining heat exchanger according to the field data.