Research On Relationship Of Non-Guaranteed Hours Between Air-conditioning Outdoor Design Conditions And Indoor Thermal Environment

Summer air-conditioning outdoor design conditions have a decisive role in the airconditioning system design as basic data.It is important to find out the influence of summer air-conditioning outdoor design conditions on the indoor thermal environment.Current determination method of summer air-conditioning outdoor design conditions in China is only based on the outdoor meteorological observation data,without considering the influence on the indoor thermal environment.It is found that magnitude difference and linear relationship exist between the non-guaranteed hours of summer air-conditioning outdoor design conditions and the non-guaranteed hours of the indoor thermal environment by establishing the quantitative relationship between them.Also,the influences of window wall ratio and other factors on the non-guaranteed hours of indoor thermal environment are analyzed.At the same time,the existing problems of current summer air-conditioning outdoor design conditions in China are put forward,so as to provide reference for the improvement of determination system of summer airconditioning outdoor design conditions in China.Based on platform of TRNSYS(Transient System Simulation Program),actual load and design load are simulated,respectively,based on actual meteorological observation data and design day data.Design day data is generated based on summer air-conditioning outdoor design conditions.And the hours of the actual load exceeding the design load is taken as the index of the non-guaranteed hours of the indoor thermal environment.In Guangzhou,Shanghai and Tianjin,the non-guaranteed hours of the indoor thermal environment are calculated based on different non-guaranteed hours of summer air-conditioning outdoor design conditions.There are magnitude difference and linear relationship between them.The non-guaranteed hours of the indoor thermal environment are not more than 10 hours based on 50 non-guaranteed hours of summer air-conditioning outdoor design conditions in the three cities.After analysis,the main reason for magnitude difference is the hourly superposition process of single load,which,in essence,reflects the lack of coincidence of summer air-conditioning outdoor design conditions.Also,universalities of the magnitude difference and linear relationship can be confirmed based on the simulation of different building models.On this basis,further study on influence of window wall ratio,ventilation rate and indoor design conditions on the non-guaranteed hours of the indoor thermal environment are carried out.It is found that the non-guaranteed hours of the indoor thermal environment are affected by the window wall ratio,the ventilation rate and the indoor temperature.When the window wall ratio decreases,the ventilation rate increases or the indoor temperature rises,the non-guaranteed hours of the indoor thermal environment will increase.Conversely,it will decrease.However,the change of indoor air enthalpy has no influence on the non-guaranteed hours of the indoor thermal environment.It is found that the values of summer air-conditioning outdoor design conditions are not accurate enough,which is the main reason for the above phenomenon.The non-guaranteed hours of the indoor thermal environment will decrease when the indoor temperature fluctuating within a certain range.If the indoor allowable maximum temperature is 28℃,the non-guaranteed hours of the indoor thermal environment will decrease by 93.6%,89.8% and 91.4%,and decrease to 0.3h,0.9h and 0.4h,respectively,in Guangzhou,Shanghai and Tianjin.