Research On Theory And Application Of Direct Evaporative Cooling Air Conditioning On Station Air Supply System

The system uses the direct evaporative cooling air conditioner as the cold source and the station air supply system as the air supply mode,aiming to provide a practical and economical cooling system solution for the current high-temperature workshop and the outdoor open and semi-open space cooling problem.Improve the working environment of people who struggle in the front line.In this paper,a series of experiments and engineering applications are carried out around the system for the problems involved in the cold source side and the station air supply system side.Firstly,the current direct evaporative cooling air conditioner is divided into cold fog type and cold air type direct evaporative cooling air conditioner according to its production medium,and the respective heat and moisture exchange processes are described.The factors affecting the cooling capacity of direct evaporative cooling air conditioners are divided into internal and external factors,among which: external factors are mainly the loss of cooling capacity caused by outdoor meteorological parameters;internal factors are mainly caused by equipment or system itself(fan and duct temperature rise)And the loss of cooling capacity of the equipment caused.It is recommended that the fan temperature rise be 0.5 to 1 °C as the estimated loss of cooling caused by the temperature rise of the direct evaporative cooling air conditioner.At the same time,the influence of different water temperature on the cooling capacity of direct evaporative cooling air conditioning is analyzed based on the wet bulb temperature.And combine their respective technical characteristics to summarize the applicable places of both.For the station air supply system side,the evaluation indicators of the station air flow organization and the influencing factors of the microenvironment effect created by the station air supply system are summarized.Secondly,the experiment is carried out on the distribution law of environmental parameters in the station area under different air supply parameters.Concluded as follow:(1)The station area is in the jet zone,and the attenuation degree of the jet depends on the wind speed of the air supply port,and the degree of jet attenuation in the station area decreases as the speed of the air supply port increases;(2)The change of the concentration of inhalable particulate matter in the human respiratory area in the station area is as follows: before use> after use;non-station area> station area;station area: away from the air supply port> near air supply port The frequency of attenuation of particulate matter in the human respiratory region of the station area increases as the wind speed increases;(4)The temperature gradient away from the axial center of the jet increases with the horizontal distance from the air outlet,and the temperature gradient first increases and then decreases;the temperature gradient in the axial direction decreases.Under different air supply speeds,the temperature gradient decreases with the distance from the air supply port;the temperature gradient at the vertical section increases with the increase of the air supply speed;(5)Change of humidity in the station area: at different frequencies,the relative humidity near the air supply port is higher,and the relative humidity gradually decreases as the distance from the air supply port increases;on the same measurement section,The relative humidity of the area within the jet section is relatively high,and the relative humidity of the area within the section of the jet is relatively low.Thirdly,the actual use effect of the system in the sizing workshop and weaving workshop,as well as on the outdoor traffic booth,was measured by field research and testing.The results show that: 1.In the sizing workshop,the average air temperature of the cold source is 25.69 ° C,and the average temperature drop is 5.74 ° C.For the station air supply system side,the average temperature of the air supply port is 28.27 ° C.The temperature was 33.5 °C.2.The average temperature of the air supply system at the air supply port of the weaving workshop is 27.38 °C,the average temperature at the cloth surface is 30.38 °C,and the average relative humidity at the cloth surface is 75.02%.3.In a traffic booth in Xi'an,the air supply temperature is stable at around 29 °C at 40 °C outdoor,and the average air supply speed in the station area is 2.8 m/s when the lateral airflow is 1.26 m/s.The ambient temperature in the station area can be maintained at around 32.2 °C.In the three projects actually investigated,the outlet temperature of the cold source can meet the cooling demand of the first-line workers,and the air supply side needs to comprehensively consider the form of the air supply port,the installation distance of the air supply port from the work area,and the installation of the air supply port.The angle can effectively utilize the amount of cooling provided by the cold source.Finally,in Urumqi,Lanzhou,and Yinchuan,direct evaporative cooling air conditioners can be used as cold sources throughout the cooling season(May to September);in Xi'an,Chongqing and Zhengzhou,and Hangzhou,Wuhan,and Fuzhou in summer,only It can guarantee about 1/2 and 1/3 of the time to use the cold source,the rest of the time can not be guaranteed,so it is necessary to assist other cold sources to ensure the temperature requirements of the work area.In the cooling season,the operating cost of the system is 1/8 of the split type air conditioner(3500W cooling capacity and 960 W power consumption).The system operates at low cost in dry areas and medium humidity areas.In short,the system can not only improve the relatively harsh working environment of front-line workers but also operate at a lower cost.Therefore,the system is a practical,economical and energy-saving ventilation cooling scheme.In the paper,there are 95 pictures,17 tables and 83 references.