| Power supply facilities is an important part of the infrastructure of cities. With the accelerated urbanization process, it is a general trend to construct underground substation. Jing An (EXPO) underground substation is the first 500kV whole underground substation in china, with many species equipments, a great capacity of heat emission, and a high requirement of guarantee for safe running of the equipments. However, now the standards related to the design of ventilation and air conditioning system for such large underground substation are not perfect, the corresponding practice experience and the reference project also lacks. Therefore, by setting the EXPO substation as the object of the study, through investigating on its ventilation and air conditioning system, find the optimized design parameters, not only be in accord with energy conservation target, but also can provide technical support for similar follow-up project.This article is divided into two parts of underground and overground to study ventilation and air conditioning system. For the underground part, first take the 220kV main transformer room for example, according to the actual measured ventilation data, simulate the flow field and temperature field of the transformer room, adopt Realizable k-εturbulence model and Boussinesq assumption. The simulation results tallies with the actual temperature data, which validated the reliability of numerical simulation. On this basis, by changing the ventilation mode, air vent height, air vent effective area etc, we can get an energy saving optimized scheme. The simulation method was used for other devices (such as reactor, station transformer room, grounding transformer room) to find the best supply parameters. Overground part adopt large space simulate, mainly research on the diffusion path of the air exhaust and the influence to the temperature of inlet air, simplified the outdoor environment, simulated the temperature of inlet air on condition that no external factors and have disturbance from outdoor wind (wind speed, wind direction), and tried various methods (increase air shaft distance, air outlets height, ground vegetation etc) to reduce the inlet air temperature affected degree.The simulation results of underground part:the most favorable mode for fresh air diffusion and cooling includes several aspects:separate the ventilating pipe in diagonal on either side of the machine, the height of air supply outlet is between 1.5-1.7m, the effective wind speed is between 4.56-5.91m/s. The optimal supply air temperature of reactor room 35kV is 30℃, the ventilation capacity is 21523m3, air supply parameters of other devices room see table 4-4.The simulation results of overground part:diffusion of air outlet without disturb from external factors will not affect the inlet air temperature, when the outdoor wind speed is b etween 0-5m/s, the air inlet temperature is affected differently, when the speed is lm/s the temperature rise maximized, the diffusion of air outlet is differed with the different wi nddirection (southeast, south, southwest), but this have little difference on the inlet air tem perature affected degree. By improving the air outlet height, planting trees, etc which cann ot change the outlet air diffusion path, but the way of increase air shaft distance, reduce ground thermal condition can effectively reduce the inlet air temperature affected degree. T herefore planted grass in air inlet area and trees have a certain space (tall, leaf area big d ensity), combined with the lawn can block out the solar radiation, reduce ground temperat ure as low as possible is an effective way to solve the problem.
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