Applicability Analysis And Outdoor Design Parameter Correction Of Evaporative Cooling Air Conditioning

The calculation of dry and wet bulb temperature in air-conditioning outdoor is the key parameter for equipment capacity selection and building energy-saving calculation.China's current civil building design specifications are used to calculate the dry and wet bulb temperatures for outdoor air conditioning in summer.Calculate the dry and wet bulb temperatures not at the same time,and are not related to each other.Its value is generally too large,which has caused the air conditioning design load in some dry and hot areas to be too large,and led to the inaccurate waste of equipment capacity selection.These problems are more obvious in the evaporative cooling air conditioner whic driven by the dry and wet bulb temperature difference.In this paper,theoretical methods,mathematical statistics and simulation calculations are used to study the outdoor dry and wet bulb temperature values of evaporative cooling air conditioners in summer,which provides a reference for the reasonable selection of outdoor design parameters of evaporative cooling air conditioners.This paper presented cooling potential indicators for direct evaporation and dew point indirect evaporation,as well as regional air conditioning demand duration indicators.The k-means clustering algorithm is used to analyze the index parameters of typical weather years of 270 meteorological stations in China through Matlab and SPSS software.The six regions with different degrees of application of evaporative cooling air conditioning technology in China are obtained.Four methods for selecting outdoor calculation parameters for outdoor air conditioning in summer are proposed: The dry and wet bulb temperatures were counted separately,the wet bulb temperature was coupled based on the dry bulb temperature,the dry bulb temperature was coupled based on the wet bulb temperature,the sum of the dry and wet bulb temperature and the wet bulb temperature were counted separately.The typical urban buildings in each applicable area are studied.Through the calculation and analysis of the air conditioning design load under different parameter selection methods,the outdoor calculation parameters that are suitable for different regional conditions are proposed.And the calculation of dry and wet bulb temperatures at different times in the current regulations in China has been revised,the correction factors for the outdoor calculation parameters of the evaporative cooling air conditioner is obtained.The main findings are as follows:1)Through the cluster analysis of the evaporative cooling potential and the duration of the air conditioning required parameters,it is found that the climatic potential of evaporative cooling in China is generally decreasing from the northwest to the southeast,and the geographical distribution of the time required for air conditioning is reversed.2)Arcgis software is used to visualize the distribution of evaporative cooling air conditioners in six applicable areas of China,and the characteristics of each region are obtained: Area I has a dry and hot climate with high evaporation potential and high demand for air conditioning in summer.Area II has dry climate,high evaporation potential and moderate air conditioning demand in summer.Zone III is mild with low evaporation potential and slightly higher demand for air conditioning in summer.Area IV has low humidity,low evaporation potential and high demand for air conditioning in summer.Area V is not suitable for air conditioning,the annual temperature is below 26 C,and there is no air conditioning demand.Area VI has high evaporation potential and low air conditioning demand in summer.3)Energy Plus software is used for the calculation of the hourly cooling load of typical meteorological year of the typical urban buildings in the summer and the air conditioning design load under the four parameter selection methods.Taked the maximum hourly load as an indicator,the suitable method for selecting outdoor design parameters of evaporative cooling air conditioning in this area was obtained.The results show that the method of "wet bulb temperature was coupled based on the dry bulb temperature" is applicable in the dry climate regions of ?,II and VI.The method of "dry bulb temperature was coupled based on the wet bulb temperature" is applicable in the humid regions of regions III and IV.4)The air conditioning design loads of typical urban buildings under four parameter selection methods are compared.It is concluded that the method of choosing outdoor design parameters of summer air conditioning based on one parameter coupled with another is more reasonable than the method of choosing outdoor design parameters of summer air conditioning based on the values of dry and wet bulb temperatures respectively.5)The outdoor dry and wet bulb temperatures used for air conditioning design calculations in China's specifications are not related to each other.The correction coefficients for outdoor design dry-bulb temperature and calculated wet-bulb temperature of five regional air conditioners are proposed: 1/0.92 in zone I;1/0.75 in zone II;0.92/1 in zone III;0.94/1 in zone IV;and 1/0.67 in zone VI.Through the above researches,the summer outdoor air conditioning calculation parameters applicable under different climatic conditions are obtained.The corresponding recommended correction coefficient is proposed for the value of the outdoor calculation parameters of the evaporative cooling air conditioner.The purpose is to provide a reasonable outdoor calculation parameter value method for the design of evaporative cooling air conditioning engineering in China,and to achieve greater energy saving in air conditioning design.