Optimal switching temperature of ventilation and air conditioning systems in underground railway equipment rooms

The ventilation and air conditioning system in underground railway equipment rooms can be operated under three conditions, and the reasonable switching of conditions is the prerequisite for realizing energy saving operation. The switching between the ventilation condition and the air conditioning condition is obtained by comparing the outdoor air dry-bulb temperature with the condition switching temperature. Taking an actual underground railway engineering project as an example, uses the MATLAB software to perform numerical calculations. By comparing the total annual energy consumption of the ventilation and air conditioning system under different condition switching temperatures, finds that there is an optimal value for the condition switching temperature. At the same time, the optimal condition switching temperature decreases with the increase of the resistance of air duct systems, the minimum operating frequency of fans and the coefficient of performance of chillers, and is affected by the climatic conditions. In the calculation example, the optimal condition switching temperature is 17 ℃ in Wuhan and Zhengzhou, and 14 ℃ in Guangzhou.