Optimization Analysis And Experimental Study On Cooling Dehumidifying Capacity Of Finned Air Cooler

The dehumidification ability of the air conditioning system has become one of the important indexes for people to evaluate the performance of the system.Among them,the cooling dehumidification method has become the most widely used air conditioning dehumidification technology with its advantages of continuous dehumidification,fast dehumidification effect and convenient operation,when cooling dehumidification equipment in use,it still has the characteristics of large size and high energy consumption.In this paper,the cooling dehumidification performance of finned air cooler is studied theoretically and experimentally.The main work and conclusions are as follows:(1)For direct evaporative air conditioning systems,Firstly,this study established the finned tube heat exchanger as the mathematical model of evaporator,the use of programming iterative calculation method of simulation calculation of the inlet air state parameters,the wind speed affect the performance of heat exchanger,simulation calculation mainly through changing the wind speed way to change the evaporation temperature,the difference of evaporation temperature between the optimal energy efficiency of the system and the maximum dehumidification amount of the system was explored,The influence of operating conditions on evaporation temperature was determined.Simulation results show that,When the inlet air dry bulb temperature is 21℃-36℃ and the relative humidity is 40-85%,the difference between the wet bulb temperature of the system and the evaporation temperature corresponding to the optimal refrigeration COP fluctuates around 10℃.When the relative humidity is higher than 40%,the difference between the corresponding evaporation temperature under the optimal refrigeration COP of the system and the corresponding evaporation temperature under the maximum dehumidification amount of the system has a linear relationship with the dry and wet bulb temperatures of the inlet air.(2)For fin tube heat exchanger low efficiency and large occupied volume.A combination of 4℃ water and micro-channel heat exchanger was proposed for the indirect evaporation centralized air conditioning system.The mathematical model of louver fin of microchannel heat exchanger was established,and the influence of air inlet state parameters,head wind velocity,cold water inlet temperature and flow rate on heat transfer characteristics of microchannel heat exchanger was simulated by programming iterative calculation method,and the comparison between microchannel heat exchanger and finned tube heat exchanger was made.Calculation results show that,when other variables remain consistent,each 10% increase in relative humidity,air volume of the dehumidification system to improve 300 m3/h,each 3 ℃ increase in the temperature,the air volume of dehumidification system to improve 100 m3/h.Moreover,when the water supply temperature is 4℃,the cooling capacity is about 20% higher than that of 7℃,and the COP of the system decreases by about 6%.Compared with finned tube heat exchanger,microchannel heat exchanger has higher volume heat transfer coefficient.Under the same condition,the heat exchange of the microchannel heat exchanger is higher and the volume is smaller.In the space occupation aspect has the big superiority.(3)The dehumidification test bed of direct evaporation air conditioning system was built,and its cooling and dehumidification performance under different experimental conditions was studied.The experimental results showed that,When the inlet air dry bulb temperature is 24-36℃ and the relative humidity is 50%-90%,the difference between the wet bulb temperature of the system and the evaporation temperature corresponding to the optimal refrigeration COP fluctuates around 15.5℃.The linear relationship between the difference between the corresponding evaporation temperature under the optimal COP and the corresponding evaporation temperature under the maximum dehumidification amount and the dry and wet bulb temperatures of the inlet air is consistent with the simulation results.