Variation in cooling load of a moving air-conditioned train compartment under the effects of ambient conditions and body thermal storage

A mathematic model was built to simulate dynamic cooling load of an air-conditioned train compartment. Using the model, the dynamic cooling loads of YZ25G train compartment were investigated under the average ambient conditions during the hottest month July, when it travels in three main railway lines of China. The effects of ambient conditions and body thermal storage on the variation in the cooling load were discussed. The results indicated that the maximum total cooling loads were between 40.4 and 43.8 kW, and the minimum between 4.5 and 33.7 kW. And significant differences in dynamic cooling load of train compartment were found between different regions (north/south and west/east) and between different periods of time (morning/night/afternoon). Compared with the dynamic cooling load, the steady cooling load calculated according to the national standard (TB1951-87) had a larger value. This means TB1951-87 is likely to overestimate the actual cooling load of a train, which can lead to a waste of energy. The calculation of dynamic cooling load can provide an adequate basis to determine the cooling load for trains traveling in different regions and periods of time.