Applicability Analysis Of Outdoor Design Parameters For Air-conditioning And Correction Method Of Design Load

The outdoor design parameters are the basis of the design cooling load calculation of air-conditioning system.The current Outdoor Design Parameters for air-conditioning determination system does not consider the indoor thermal environment at non-guaranteed levels.Researches on the load difference between the peak design cooling load in design day and the design cooling load of indoor thermal environment at non-guaranteed levels were not sufficient.In this paper,the air-conditioning design days at various non-guaranteed levels were constructed by using the methods in Chinese Code.Guangzhou,Changsha and Beijing were selected as the representative cities of the three climate zones to explore whether the design cooling load of energy-saving buildings or rooms can meet the requirements of the indoor thermal environment at corresponding non-guaranteed levels.Propose the improvement method of constructing the meteor ological parameters of the design day in summer and air conditioning design cooling load correction method.The cooling load calculation model is established based on the radiation time series method and the periodic response factors method.Cooling load calculation model was used to calculate the cooling loads for the singleouter-wall rooms,double-outer-wall rooms and energy-saving buildings with the air-conditioning design days and the historical hourly meteorological observation data measured for many years.The load difference rate between the peak design cooling load in design day and the design cooling load of indoor thermal environment at non-guaranteed levels was analyzed.Evaluate the applicability of the outdoor design parameters for air-conditioning design in the air conditioning system design of energy-saving buildings or rooms.The results show that the air-conditioning design days cannot represent the near extreme design conditions of all single-outer-wall rooms in energy-saving buildings,as well as double-outer-wall rooms and energysaving buildings.The load difference rate increases gradually with the increase of the non-guaranteed levels.Moreover,for the most single-outerwall rooms,double-outer-wall rooms and energy-saving buildings,the design cooling load calculated by Chinese code is overestimated,especially for energy-saving buildings.Compared with the hot summer and warm winter regions and the hot summer and cold winter regions,under the same non-guaranteed level,the distribution of load difference rates in the cold regions represented by Beijing is more dispersed,and the load difference rates are significantly higher than those in the other two climate regions.In order to improve the construction method of the air-conditioning design day,the hourly solar irradiance in design days was calculated by ASHRAE solar radiation model,and the cooling load difference rates between the peak design cooling load in design day and the design cooling load of indoor thermal environment for 50 non-guaranteed hours have decreased.The improved outdoor design parameters for 50 non-guaranteed hours are more suitable to air conditioning system design.The design cooling load of air conditioning for 50 non-guaranteed hours is corrected by the correction factors.Based on the CART regression tree algorithm,a prediction model for the correction factors of air-conditioning design cooling load for 50 non-guaranteed hours is established,and a correction table suitable for energy-saving buildings or rooms is given.The cooling load difference rates are significantly reduced after the correction,which verifies the accuracy of the correction table.The cooling loads can ensure that the corresponding indoor thermal environment satisfy the prospective claims to a certain extent which calculated with the outdoor design parameters and the correction factors in table.