| Capillary radiation air conditioning system has attracted more and more attention for its advantages of energy saving,thermal comfort,etc.However,under cooling conditions,condensation may occur in radiant room.Condensation not only reduces the heat transfer performance of radiant panel,but also affects indoor environmental sanitation,which is the main reason that hinder the promotion of radiation air conditioning system.There are many reasons for condensation,aiming at the risk of condensation caused by the increase of indoor population,this paper study the water supply control method for condensation prevention.In this paper,we take a capillary radiation air conditioning room as the research object,and establish models based on Design Modeler software of ANSYS platform,and conduct a simulation study on water supply for condensation prevention for capillary radiation air conditioning system under cooling conditions by means of combining the theoreticl analysis combined with numerical simulation by Fluent.The main research work is as follows:(1)Establish and verify the capillary radiant panel model.Study the surface temperature distribution and cooling capacity of radiant panel under different water supply temperature(16℃～22℃)and water supply velocity(0.018m/s～0.053 m/s)under steady state conditions.Under unsteady conditions,study the variation of surface temperature of radiant panel from regulation time to another stable state when the water supply tempreture is adjusted in increments of 2 ℃ and when the water supply is turned off.(2)Establish and verify the capillary radiation air-conditioning room model.Study the relationship between the dew point temperature of the air around the radiant panel and four factors(i.e.surface temperature of radiant panel,moisture source intensity,fresh air exchange rate and absolute humidity of fresh air)by using the orthogonal experiment method under steady state conditions.Study the variation of the dew point temperature of the air around the radiant panel under the unsteady state condition when the number of indoor personnel was increased by 1～4.(3)Make regression analysis on the variation of surface temperature of radiant panel and the dew point temperature of the air around the panel by the Origin software under unsteady working conditions.Formulate water supply strategies for condensation prevention when the indoor personnel number is respectively increased by 1～4.The results are as follows:(1)Under steady state conditions,surface temperature of radiant panel increased in the range of 21.9℃ to 25.0℃ when the supply water temperature increased from 16.0℃ to22.0℃ with an interval of 1℃.The surface temperature of radiant panel was 22.8℃,22.6℃,22.0℃ when the velocity of supply water was 0.018 m/s,0.035 m/s,0.053 m/s,respectively.Under unsteady state conditions,with the increase of water supply temperature,the surface temperature of the radiant panel increased with a negative exponential function,and eventually stabilized.With the increase of the adjustment temperature difference,the growth rate of the surface temperature of the radiant panel increased,and the temperature value when the system reaches the steady state again also increased.(2)Under steady state conditions,there was a liner relationship between the dew point temperature of the the air around radiant panel and four factors,and the degree of influence on the dew point temperature of the air around of four factors in descending order was absolute humidity of fresh air,moisture source intensity,fresh air exchange rate and surface temperature of radiant panel.Under unsteady state conditions,when the number of indoor personnel increased,the air dew point temperature of the attached layer increased with a negative exponential function,and finally tended to be stable,and the growth rate of the air dew point temperature of the attachment layer increased with the increase of the number of personnel.(3)Under water supply temperature adjustment conditions,with the increase of the number of personnel,the regulation time was advanced and the regulation temperature increased accordingly.When the number of personnel increased by 1,2,3,4,the corresponding regulation time and temperature were 28.8 min/18℃,14.7 min/20℃,9.1min/20℃ and 5.8 min/22℃ respectively.Under the condition of closing water supply,when the number of personnel increased by 1,2,3,4,the corresponding time of closing water supply was 34.7 min,16.9 min,10.3 min and 7.4 min respectively.Based on all above research,the effective and optimal water supply regulation mode is studied innovatively under the condition of increasing humidity source caused by increasing indoor personnel,which provides reference for the research on the anti-condensation control operation of radiant cooling air conditioning system,and provide theoretical support for the promotion and application of the radiant cooling air conditioning system. |
