Health & Environmental Research Online (HERO)


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2599740 
Journal Article 
A New Method of Cooling and Heating Load Calculation 
Zhang, Shu; Zheng, M; Wang, X; Zhang, W 
2009 
343-350 
WOS:000276109800049 
Cooling and heating load calculation is a main basis of design and equipment selection of air-conditioning system. The room temperature is considered as a constant in the previous calculation method, but in fact the room temperature is fluctuant. Because of the envelope structure and indoor items absorb heat with the room temperature rises and release heat with the room temperature falls, the variation of the actual load is tended to be gentle, which is also one of the main reasons leading to the past design load is larger than the actual load. Therefore a new method called variable-temperature load method (VTLM) is presented in this paper considering the thermal storage performance of the room and the better room temperature sequence is obtained in the allowable range. Then the room temperature is controlled according to this sequence to calculate the design load which is called variable-temperature load (VTL). It is much smaller than the design load calculated by the past method. The room heat transfer dynamic model is established based on the numerical method of the heat capacity particle series and the finite difference method is adopted to separate and solve the model. The concept of variable-temperature load coefficient (VTLC) is introduced, which is a ratio of the calculation load based on VTLM and the calculation load based on the routine method. Several kinds of typical room structure in Beijing and Harbin are selected to simulate. The results show that when the indoor temperature fluctuates in the range of +/-0.5 degrees C, the cooling load calculated by VTLM is about 70 percent of that calculated by routine method and the heating load is about 85 percent. The main impact factors of VTL are analyzed, the bigger the variation interval of the room temperature and the better the room heat stability, the smaller the VTLC; the smaller the temperature difference between indoor and outdoor and the smaller the air infiltration through the window, the smaller the VTLC. 
Cooling and heating load calculation; Room temperature; Variable-temperature load method (VTLM); Numerical simulation