Study On Operation Performance And Indoor Heat And Humidity Of Gravity Circulation Cabinets In Different Seasons

With the continuous development of air-conditioning systems in recent years,radiant air conditioners have attracted more and more attention due to their better thermal comfort.However,due to the characteristics of summer humid climate in most parts of China,the promotion of radiation systems is affected by Limitation,and the appearance of the capillary gravity circulation cabinet creates conditions for the radiation system in practical applications,and broadens the heat exchange mode of the radiant air conditioner.The gravity circulation cabinet can be used for both cold and heat due to the dehumidification function,and can be combined with other radiation systems.It promotes the application and promotion of capillary network radiation system.In this paper,the experimental test and simulation analysis method are used to study the capillary gravity circulation cabinet.The gravity circulation cabinet and the room are tested in summer and winter respectively.The model of the gravity circulation cabinet is built according to the test data.The gravity circulation cabinet is simulated by CFD under summer and winter conditions,and is analyzed the influence of different variables(water supply temperature,water supply flow,indoor ambient temperature)on the heat transfer performance of the capillary network in the gravity circulation cabinet,including the cooling and heating performance.The ratio of heat transfer is used to fit the cooling and heating formula,and the calculation formula that can be applied to engineering practice is obtained.The room model of the gravity circulation cabinet is built according to the actual size of the test room.The temperature field,velocity field and humidity field under summer and winter conditions were analyzed.This paper uses the thermal comfort index PMV-PPD to analyze the influence of the gravity circulation cabinet on the indoor thermal comfort,and uses the energy utilization coefficient EUC to compare and analyze the energy saving situation and applicability under different operating conditions.The research results show that when adjusting the room set temperature and humidity,the adjustment of the water supply temperature is more obvious than the adjustment of the water supply flow,and the gravity circulation cabinet has self-adjusting ability when the indoor ambient temperature changes.For the indoor environment under summer conditions and winter conditions,overall,under stable conditions,the indoor temperature in winter and summer is in the range of20~26°C,the relative humidity is in the range of 35%~55%,the outlet velocity is in the range of0.3~0.4 m/s.After the analysis of the heat transfer performance of the gravity circulation cabinet,the cooling capacity of the gravity circulation cabinet is about 1000 ~ 1600 W in summer,the dehumidification amount is in the range of 0.5 ~ 1kg/h,and the proportion of cooling of the radiant panel is 9%~10%;The amount of cooling and the amount of cooling does not exceed10%,and the proportion of heat supplied by the radiant panel is 11% to 12%.However,because the heat transfer coefficient of the gravity circulation cabinet in summer is greater than that in winter,the cooling capacity of the gravity circulation cabinet is slightly stronger than the heating capacity.For the PMV-PPD evaluation index,the human body has good thermal comfort and low predictive dissatisfaction rate under two operating conditions in winter and summer.Under summer conditions,the PMV value is between 0 and 0.5,and the predicted dissatisfaction is within 15%,in winter conditions,the PMV value is between-0.5 and 0,and the predicted dissatisfaction is within 10%.For the EUC evaluation index,the energy utilization degree is different under the two operating conditions in winter and summer.The summer EUC value is greater than 1,and the winter EUC value is less than 1.It can be judged that the summer gravity circulation cabinet energy utilization effect is better than the winter,Therefore,the applicability of the gravity circulation cabinet in summer is high.