A method to calculate wall heat fluxes of electrical equipments based on overdetermined linear equation

Cooling load of air-conditioning systems in underground space mainly refers to heat released from multitudinous electrical equipments. Calculation of the total amount of heat release is of great importance to the underground ventilation and air conditioning systems during design stage for indoor thermal environment. A method based on overdetermined linear equation is applied to calculate heat release fluxes of equipment surfaces in an underground space. Firstly, a field test in an underground hydropower station was carried out. Temperatures of electrical equipment surfaces, walls, underground indoor air and dimensions of electrical equipments were obtained. Conventional methods based on heat transfer theory can obtain the results with a standard error of 0.59, which is a relatively high value. On basis of overdetermined linear equation, the method combines on-site temperature measurements with numerical simulation to calculate wall heat fluxes. When seven testing points are selected in the on-site temperature measurements for calculation, the heat release fluxes of three equipment surfaces can be obtained with a standard error of 0.07. The method based on overdetermined linear equation is an effective way to determine wall heat fluxes of electrical equipments in air conditioned space.