Research On The Coincidence And Design-day Generating Method Of Summer Air-conditioning Outdoor Design Conditions

Air-conditioning outdoor design conditions which have a decisive role in the calculation of air-conditioning cooling load and the selection of air-handling equipment are the fundamental data for system design.The method system of outdoor design conditions were imperfect: the data base updated in a timely manner,the distribution law of single meteorological elements was not strong,the coincident characteristics of the meteorological elements was not considered in essence,the method of generating design-day data was not perfect.Therefore,this paper compensate for the above deficiency by putting forward new determination methods of air-conditioning outdoor design conditions.To begin with,the generalized Pareto distribution(GPD)was used to fit the extremely high dry-bulb temperatures and the outdoor design DB temperature was calculated in Tianjin of China,1981-2010.After that,the generalized Pareto distribution response to different meteorological elements,different climate types,statistical time,and data sizes were investigated.The results show that the air-conditioning outdoor DB temperature based on GPD function is slightly higher than the empirical cumulative distribution function(ECDF)method with the non-guaranteed 50 h per year,the difference of DB temperature is less than 0.1℃ and the WB temperature are the same.The GDP and ECDF methods can be used to analyze the different climatic types and different meteorological elements.They can also reflect the change rules of climate.But,comparing with GPD method,the robustness of ECDF method is gradually reduced with the decrease of the sample collection frequency,the shorter of the statistical time and the decrease of the non-guaranteed probability.The joint distribution function of DB temperature,WB temperature and solar radiation is constructed by using Copula function,which reflects the coincidence of the meteorological elements from a probabilistic perspective.The results show that the current method is not fully consider the coincidence of meteorological elements,the true non-guaranteed degree is much higher than the two parameters and three parameters joint non-guaranteed degree.Therefore,the selection of non-guaranteed rate should consider the applicability of outdoor design conditions with the correlation between the indoor and outdoor environment.The design-day data for air-conditioning load calculation are selected to represent the typical days of the extreme climatic conditions,the design conditions are normalized with consider of the influence on the air-conditioning cooling load.The results show that design-day data reflect the regional characteristics,the maximum value of DB temperature is at 15 o’clock not 13 o’clock in Tianjin.The value of the meteorological elements are closely related with their weight coefficients,it makes the average WB temperature 21.7℃ is far less than the standard value 27.2℃.