The Applied Study On Combined Operation Of Evaporative Cooling And Mechanical Refrigeration In North China

In the temperature and humidity independent control air conditioning system,the latent heat load of the air conditioning building is borne by the humidity control system,and the sensible heat load is mainly borne by the temperature control system.The source of high temperature cold water can be a natural cold source,and it can also be provided by a high temperature chiller and an evaporative cooling chiller.According to the current equipment performance,the COP value of the high temperature chiller under the rated operating condition is about 6.81⁸.58^[1]when the water temperature is 16.The COP value of the indirect evaporative cooling water chiller can reach more than 15,which is much higher than the COP of the high temperature chiller.However,the use of evaporative cooling units is restricted by outdoor meteorological conditions.The ideal outlet temperature of indirect evaporative chillers is the dew point temperature corresponding to outdoor environment,while the current outlet temperature of the unit is generally 2³ degrees higher than the ideal outlet temperature.Because of this,the evaporative cooling equipment is only used in the dry area of Northwest China to be independent of the cooling capacity needed for air conditioning.If it is used in other areas（middle humidity area）,it can only run with the high temperature water chiller.This project will analyze the economy of the joint operation of the evaporative cooling chiller and the mechanical refrigeration high temperature chiller providing the high temperature for the THIC air conditioning system in North China.First of all,on the basis of the average outdoor meteorological parameters in Beijing area,used the electric energy consumption which can remove the total heat with 1kW sensible heat as the evaluation index,calculates the energy consumption of the primary air return system,the fan coil unit air system and the THIC air conditioning system respectively,and obtains the energy consumption of the three air conditioning systems under different heat humidity ratio and different fresh air ratio.Secondly,based on the three typical buildings located in Datong,Zhangjiakou and Beijing（hotel,shopping malland office building）as examples,calculates and analyzes the economy of the joint operation of the evaporative cooling chiller and the mechanical refrigeration high temperature chiller providing the high temperature for the THIC air conditioning system.Through the calculation of the hourly cooling load of air-conditioned building,the hourly refrigerating capacity and the hourly affordable thermal cooling load of indirect evaporative cooling chiller under different yielding water temperatures,gives the best equipment matching coefficient and corresponding payback period under the jointly run of the two kinds air conditioning units.The results shows that the total operation cost is the lowest when the matching coefficients are 0.45,0.63 and 0.13 respectively in the three buildings of hotel,shopping mall and office building,and the corresponding additional equipment payback period are7.5,10.3 and 13.1 years respectively in Datong;when the capacity matching coefficient are 0.49,0.56 and 0.16,the total operation cost of summer air conditioning is the lowest,and the corresponding additional equipment investment recovery period are 7.5,10.5and 13.0 years respectively in Zhangjiakou;when the capacity matching coefficient are 0.38,0.45respectively in the two buildings of hotel and shopping mall,the total operation cost of summer air conditioning is the lowest,and the corresponding additional equipment investment recovery period are 10.0,13.0 years respectivelyin Beijing,and the office buildings in Beijing should not be used in this way.The calculation results provide reference for the application of evaporative cooling equipment in North China.