The Usability Analysis Of ERA Data In Outdoor Calculation Parameters For Air Conditioning Design

Meteorological parameters are the basic data that reflect the change of outdoor climate environment,including air temperature,solar irradiance,relative humidity and so on.it plays an important role in the calculation of air conditioning load and the generation of outdoor calculation parameters for air conditioning design.At present,the way to obtain the measured meteorological data is limite d and expensive,which has caused inconvenience to the relevant scientific research work.Reanalysis data ERA5 which developed by ECMWF is a global atmospheric reanalysis product,which has the advantages of long time scale,good data stability and wide co verage space,but its deviation in the application of design cooling load calculation instead of measured data needs to be further discussed.In this paper,using the measured data of China National Meteorological Administration as a reference,the ERA5 da ta of eight typical cities in five thermal design zones in China are selected to make a comprehensive error analysis of dry bulb temperature,wet bulb temperature and horizontal total solar irradiance.The monthly deviation,the annual deviation,the corre lation coefficient and the root mean square deviation of the hourly values of the daily mean values of each parameter are calculated.At the same time,the annual average dry and wet bulb temperature of 50 hours is not guaranteed based on the ERA5 data and the measured data.Two typical days in summer and winter are selected respectively,and the radiation values of each time in the 22 years from 1993 to 2014 are added hourly,and the deviations between them and the measured values are compared.Referring to the determination principle of outdoor solar irradiance in the existing code,the basic solar irradiance curves of different data sources are drawn.The statistical results show that the reanalysis data of most cities have a good correlation with the mea sured data,and can accurately restore the outdoor climate environment.In Changsha with less deviation,the annual deviation of daily dry bulb temperature,is less than 0.5C,and the range of annual deviation of wet bulb temperature and horizontal total ra diation is 0.36-0.66℃and 28.3W/m~2,respectively,while in Chengdu,the range of annual deviation of dry bulb temperature and wet bulb temperature is 0.93-1.65℃and 0.62-1.05℃,respectively,and the annual deviation of global horizontal irradiance is 30.3-45.4W/m~2.In the statistics of the average 50-hour dry and wet bulb temperature and basic solar irradiance over the past 30 years,the ERA5 data are very close to the measured data.For the room with single exterior wall,used the periodic response coefficient method and the radiation time series method to calculate the cooling load.Each city randomly selects 20000 groups of design combinations composed of different room characteristic parameters,and calculates and compares the summer p eak cooling load difference rate when ERA5 data and measured data are used as outdoor meteorological input parameters.The calculation results show that there are some differences in load difference rates among different cities,but generally speaking,the availability of ERA5 data in cooling load calculation is higher.Take Changsha and Beijing as an example,when the load non-guarantee rate is 0.4%,1%and 2%respectively,the load difference rate of more than 95%in Changsha is less than 5%,while in Bei jing,the difference rate of 92.1%,82.3%and 53.3%is less than 5%.