The Variable Air Volume Analysis Of The Subway Air Conditioning Based On The Relative Warmth Index (RWI)

With large-scale metro construction, the subway platform environment has become an issue abstracting more and more researchers'concern. Establishing a good subway environment is not only for providing a safe and comfortable travel environment for passengers, but also of practical importance to save energy, reduce construction costs and operating costs.In the dissertation, the hourly load of personnel, lamp boxes, billboards, platform screen doors and the accessory equipment on the platform of a metro station in Xi'an were calculated in detail, according to the forward air-conditioned subway preliminary design. Then, two variable air volume (VAV) air conditioning schemes were put forward on the basis of load calculation. In one of the VAV schemes, the design temperature of the platform kept at 28°C; while in another scheme, the hourly target temperature of the platform calculated with relative warmth index (RWI) was used as the design temperature. Comparing the supply air rate of these two schemes, it was concluded that in order to meet the thermal comfort requirements without great increase of energy consumption, the scheme setting the platform temperature in accordance with RWI values was recommended.For the air conditioning scheme described above, the computational fluid dynamics (CFD) simulation method was applied to analyze the VAV effects under the modes with the subway air-conditioning system at its 85% load and 100% load, respectively. The standardκ?εturbulence model was used as the physical model, and on the basis of high-quality meshes generated, the physical quantities of interest were discretized and the temperature field and velocity field of the platform were obtained. By analyzing the temperature field and velocity field and other related data, it was revealed that the VAV subway environmental control scheme could achieve the goal of energy saving. Moreover, some useful exploration has been carried out herein, such as mesh generation for complicated models, simplification of boundary conditions and transient processes, which could provide some reference for similar numerical simulation issues.