| The radiant ceiling air conditioning system is energy-saving and comfortable.The radiant ceiling bears the indoor cooling load,and the independent fresh air system bears the indoor wet load.However,due to the temperature difference between the surface of the ceiling and the indoor air,there is a risk of condensation on the surface of the ceiling,resulting in the insufficient total cooling capacity.In order to solve these two problems,it is generally adopted to form a layer of air layer with fresh air attached jet and isolate indoor hot and humid air to prevent condensation of radiation ceiling and improve the total cooling capacity.However,limited by the upper limit of fresh air volume,the coverage area of fresh air attached jet is small,and the anti-condensation effect is not good.At the same time,the average dew point temperature of the air layer（attached layer）5cm away from the surface of the radiation ceiling is used to evaluate the anti-dew effect,and the area covered by attached jet is not more carefully distinguished from the area not covered by attached jet,so the evaluation of anti-dew effect is not accurate enough.So this topic from the improvement to prevent radiation ceiling surface condensation effect and improve radiation air conditioning refrigerating capacity two goals,put forward by combining the radiation in the air conditioning system for the first time in domestic outdoor and indoor air return system,improve attached with a jet of coverage,to improve the radiation ceiling condensation prevention effect at the same time to promote the concept of total radiation air conditioning refrigerating capacity purpose.At the same time,three concepts of adhesion zone,adhesion jet coverage rate and average dew point temperature in adhesion zone are proposed.In this study,the coverage rate of attached jet was used to characterize the influence range of attached jet,and the average temperature of attached region was used to characterize the dewpreventing ability of attached jet.The average dew point temperature in the attached area was taken as the auxiliary evaluation standard,and the coverage rate was taken as the main evaluation standard to comprehensively evaluate the anti-condensation effect of the attached jet on the radiation ceiling.The experimental results show that the new return air attached jet is effective in preventing condensation and feasible to increase the total cooling capacity of radiation air conditioning.Experimental results show that compared with pure fresh air,the new return air attached jet covers a wider area,has stronger anti-condensation ability,and improves the total cooling capacity of radiation air conditioning.In the area not covered by fresh air,the dew point temperature of fresh return air attached jet can be reduced by 6.31℃at most compared with pure fresh air,and the total cooling capacity of radiant air conditioning increases by 6.29% with the decrease of fresh return air ratio.Through the experimental data,after verifying the accuracy of the simulation model,this project extended simulation on the parameters that affect the formation of attached jet effect:air supply speed,total width of air supply ports,number of air supply ports,length to width ratio of the room,and explored the influence of dew-preventing effect and total cooling capacity of the new return air attached jet.The simulation results show that :（1）The average dew point temperature in the attached area rises with the increase of air supply velocity,air supply port width and air supply port number;The average dew point temperature in the attached area decreased with the increase of the aspect ratio of the room.（2）The coverage of adhesive jet increases firstly and then decreases.The highest coverage rate is 70.15% when the wind speed is 2m/s.When the air supply speed is 1m/s-3m/s,the anti-condensation effect is the best when the wind speed is 2m/s.The total cooling capacity of the radiant air conditioner increases with the increase of the attached jet velocity.The total cooling capacity of the radiant air conditioner at the air supply speed of 3m/s increases by 53.39% compared with that at the air supply speed of 1m/s.（3）The coverage rate of attached jet increases with the increase of tuyere width.When the width of air supply port increases from 1.8m to 2.4m,the coverage rate of attached jet increases by 14.87%.Comprehensive evaluation when the width of the air inlet is 1.8m-2.4m,the anti-condensation effect of 2.4m is the best.The total cooling capacity of the radiant air conditioner increases with the increase of the width of the air outlet.The total cooling capacity of the radiant air conditioner with the width of the air outlet of 2.4m is 10.35% higher than that with the width of the air outlet of 1.8m/s.（4）The coverage rate of attached jet increases with the increase of the number of air supply outlets.When the number of air supply outlets increases from 1 to 4,the coverage rate of attached jet increases by 16.71%.In the comprehensive evaluation,when the number of air supply outlets is 1-4,the anti-condensation effect of 4 air supply outlets is the best.The total cooling capacity of the radiant air conditioner increases with the increase of the number of air outlets.Compared with the number of air outlets,the total cooling capacity of the radiant air conditioner increases by 16% when the number of air outlets is 4.（5）The adherent jet coverage decreases with the decrease of room aspect ratio.When the aspect ratio decreases from 1.33 to 1,the adherent jet coverage rate decreases by 6.12%.In comprehensive evaluation,when the room aspect ratio is 1-1.33,the adhesion jet with the room aspect ratio of 1.33 has the best anti-condensation effect.The total cooling capacity of the radiant air conditioner increased firstly and then decreased with the decrease of the aspect ratio of the room.The maximum cooling capacity was 170.07 W /m2 when the aspect ratio of the room was 1.11.The above simulation study shows that the quality of the anti-condensation effect of attached jet is positively correlated with the width of air supply ports,the number of air supply ports and the ratio of length to width of the room,and there is an optimal solution relationship with the air supply velocity.The total cooling capacity of radiant air conditioning is positively correlated with the air supply speed,air supply width and the number of air supply ports,and has an extreme relationship with the length-width ratio of the room.In this paper,the effects of room air supply velocity,air supply port width,air supply port number,room length to width ratio on dew-preventing effect of attached jet and total cooling capacity of radiant air conditioning are studied by combining experimental and simulation methods.The law of the coverage rate of attached jet and the average dew-point temperature in attached area changing with variables is obtained.It provides an important basis for further research on preventing condensation and improving cooling capacity of radiant ceiling air conditioning. |
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