Airflow Simulation And Energy-Saving Transformation In The Carriage Of Air-Conditioned Train

Along with the rapid development of economy, the challenge of energy and environment for our country are more and more difficult. And the country improved energy-saving to a higher degree of attention, while the energy-saving of train air-conditioning plays an important role in traffic system. On the other hand, with the improvement of people's living standard, it is more and more higher for the thermal comfort requirement of the carriage environment. However, in actual operation, there are phenomena of high energy consumption, poor air quality, uneven distribution of temperature, humidity and wind speed in air-conditioned train, which required fully consideration for both factors of energy efficiency and thermal comfort when carrying out the research. As the special operating conditions of train air-conditioning, some energy-saving methods widely used in the architecture field can not be directly applied to air-conditioning in trains, therefore it is necessary to make analysis and comparison in both theoretical and experimental to verify the feasibility and effectiveness.In response to the high comfort, low energy consumption in current social, it calculated and analyzed the actual air conditioning load of the train in the actual operation. On this basis, it used commercial software to simulate the airflow in train in primitive condition (the maximum capacity) and condition (actual cooling capacity). By the comparative analysis, it found that when the train air-conditioning used cooling capacity which equaled to the actual running load, it was possible to save energy while ensure thermal comfort in the carriage.The typical air-conditioned train(YZ25G 344871,YW25G 673188 tow carriage) was selected as the prototype. On the basis of simulation, it made frequency conversion transformation of the train air-conditioning unit, and made tracking run tests on the modified vehicles. By the way of data collection and field investigation, it analysed the effect of energy saving of the train air conditioning which used frequency conversion technology. The results showed that the effect of energy saving of air conditioning is more than 20% during the running period. It was found that the actual measurement data and simulation results have good agreement by the comparison of the data of numerical simulation and test results. In the actual operation, it was discovered that after the frequency conversion transformation, the train air-conditioning's safety and stability improved, and it was very good to solve the problem of hysteresis and instability in traditional manual control mode, and improved the condition that the temperature in the carriage was sometimes high and sometimes low, and can't meet passengers'needs.Due to unreasonable of the current design of the ventilation system, which caused uneven air distribution(the air flow and wind speed varied widely between each inlet), there still existed the phenomenon that hot and cold are non-uniform between inside of the carriage even after making frequency adjustment. Therefore, based on the frequency transformation in the train air conditioning, it used numerical simulation method to simulate the two conditions which using non-uniform air distribution (the inlet air flow is unequal) and uniform air distribution (the inlet air flow is equal). The results showed that in the uniform air condition the temperature was 24-27℃and wind speed was less than or equal to 0.3 m/s, as well as the PMV value keep in a cool state of -1~0. At the same time the uniformity of temperature and velocity distribution were improved.