Study On Cooling Performance With Capillary Different Laying Ways

Capillary radiation cooling system,as a new type of high temperature water cooling system,has good advantages of high comfort,quietness and health,good cold storage ability,space saving and flexible layout as well as the connection with low grade energy and energy saving.So there is great application potential for capillary radiant cooling system.However,the existing research pay more attention to the theoretical calculation of cooling system,simulation or the single layout experiment research,while there is hardly experimental comparison of the capillary cooling performance of different layout.By the means of simulation and experiment,this paper aims to study the cooling performance of capillary network of different laying ways(ceiling,wall and floor),based on two experimental rooms(410,412)in the laboratory building of Chongqing University.The experiments were designed in the two conditions(fixed supply water velocity with varied supply temperature,and fixed velocity with varied temperature).By the analyzation of tested parameters(such as the indoor temperature,surface temperature,supply water temperature and flow rate),the relation between supply water temperature,flow rate and work area temperature,level and vertical temperature,vertical disapproval rating,radiation surface temperature,other surface temperature,mean radiant temperature,PMV,PPD as well as effective heat release were discussed.Then the best laying ways,supply temperature and velocity in the tested conditions were confirmed by the orthogonal experiment.Finally,a physical model,verified by the experimental data,was built to optimize the actual operation.The following experimental results were concluded.First of all,when the indoor temperature stabilized,with the different supply water temperature or velocity,the average temperature of occupied zone for all 3 laying ways were no more than 28? meanwhile the indoor vertical temperature difference is less than 2 ?.The indoor temperature field stratified for all three laying ways.In comparison,ceiling laying was the preferred with the least vertical and level temperature difference and stratification and the most satisfying comfort,while both the wall laying and the floor laying were uncomfortable,which got the maximum level temperature difference and vertical temperature difference respectively.Secondly,when stabilized,with the different supply water temperature or velocity,the radiant surface temperature for all 3 laying ways satisfied the requirements of standard.Because of the decrease of the thickness of the floor,wall and ceiling,the response time that the cooling surface temperature stabilized reduced,the surface temperature decreased as well.Then,when stabilized,with the different supply water temperature or velocity,it was found that for the 3 laying ways the wall laying way could get the maximal effective heat release by unit area,followed by the ceiling and floor laying.The orthogonal experiment showed that the influence on the indoor comfort by capillary laying ways,supply water temperature and velocity decreased in turn.The ceiling layout could lead to the more comfortable environment.Therefore,in the tested conditions.,compared with the other combination of different supply temperature and supply velocity,20? for temperature and 0.1m/s for velocity of the ceiling layout were the optimal group.Finally,the simulation results from the Airpak software showed that the model,half paving of capillary in the ceiling,could be verified well by the experiment results.The indoor temperature in the simulated full paving condition was obviously lower than that in the tested half paving condition.Therefore,when the laying area of capillary network increased,higher supply temperature and lower velocity could realize the same indoor comfort and energy saving.