Research On Energy-Saving And The Temperature-Humiditv Decoupling Mechanism Of Constant Temperature And Humidity AC System By Double Circuit Cooling Coil

Constant temperature and humidity air-conditioning(AC)system,as a kind of technical AC system,has been widely applied in the situations where temperature,relative humidity,cleanliness,uniformity and stability are highly requested,such as electronic industry,scientific research and cultural relic protection.In the conventional constant temperature and humidity AC systems,in order to ensure the control accuracy,the process air is cooled down and dehumidified simultaneously by controlling method of the fixed chilled water flow rate and fixed dew point,which is a coupled heat and mass transfer process.The outlet air temperature and humidity of the cooling coil might be even lower if dealing with a large amount of latent heat load.Reheating and re-humidifying are needed for energy compensation in order to satisfy the demand of supply air parameters,which leads to great energy consumption.In this paper,experimental research and corresponding regression model are carried out based on double circuit cooling coil(DCCC)in the AC system to achieve energy conservation operation.Firstly,the decoupling mechanism of air temperature and humidity is firstly revealed;then,the quantitative evaluation of decoupling degree,which is effected by the chilled water flow rate and chilled water temperature,is obtained;finally,the optimal relationship between the sensible and latent heat loads and the water side parameters of DCCC is obtained.The several work of this paper is as follows:(1)A constant temperature and humidity AC system applied in temperature and humidity independent control(THIC)based on DCCC was designed and established.Experiments and energy-saving analysis were conducted under various working operations.The build and debug work between hardware and software were carried out.These efforts provide reliable guarantee for the accuracy of the experimental data from this system.(2)The fitting results of the outlet air parameters and the chilled water flow rate and chilled water temperature of DCCC were obtained by using Box-Behnken design(BBD)and response surface method(RSM).The regression model was established to predict the outlet air parameters of DCCC.The optimal water side parameters under a specific load,which represented the lowest energy consumption of the system,were obtained according to the regression model.The energy consumption comparison and energy-saving potential distribution analysis were conducted based on the conventional and optimal AC systems.(3)The influence of the chilled water flow rate and chilled water temperature on the response surface were analyzed under the fixed inlet air parameters of DCCC.In order to quantify the decoupling degree caused by the chilled water flow rate and chilled water temperature,the concept of the decoupling factor was introduced and the equations were built.The results showed that the degree of the outlet air humidity ratio of DCCC influenced by the chilled water temperature was 75.68%,while the degree of the outlet air temperature of DCCC influenced by the chilled water flow rate was 43.01%under the measured working operations.A decoupling of the outlet process air conditions,temperature and humidity ratio,can be obtained as the inlet chilled water flow rate and inlet chilled water temperature are varied.