Design And Optimization Research Of Capillary Radiant Air Conditioning System

With the improvement of people’s living standard,the indoor thermal comfort requirements are also increasing,but this will lead to energy consumption,environmental pollution and other issues.Capillary radiant cooling is a technology which uses renewable energy.It is environmental friendly,energy conservation,and also represents the future trends of HAVC technologies.First,a building in Tianjin was chosen as the research object and one office room was used as an example to illustrate the design method of the capillary radiant air conditioning system,with the displacement ventilation system as the fresh air system.The corresponding design parameters were deduced,such as the supply air temperature being22℃,air supply velocity being 0.22m/s,cooling capacity per unit area of the capillary radiant cooling being 60W/m2 and the cooling area being 25m2.And the work of water conservancy,the type selecting were finished.Then the capillary radiant air conditioning system was analyzed by using the Airpak software to simulate.Finally,the design parameters were changed to optimize the analysis of the capillary radiant air conditioning system.The following contents are the research results.(1)The average temperature of indoor environment is about 26 ℃.Under the joint control of capillary radiant cooling and displacement ventilation,temperature gradient in the occupied zone is about 1.3℃/m,and average air velocity is 0.0862 m/s.Indoor mean PMV value is 0.13,and PPD is 6.37%.These parameters are satisfied to the requirements and the design method is reasonable.(2)By studying the air velocity,the number of air supply outlet,obtain the two factors have little effect on indoor environment of capillary radiant air conditioning system.It is recommended a lower wind speed that can be less the cost of unit and more in line with the feature of displacement ventilation,flexibly to choose the number of outlet.(3)By changing the outlet arrangement,get conclusions that the ceiling and upper air supply are unsatisfactory,the indoor average temperature being about 26.7 ℃,the PMV-PPD index beyond the reasonable range.And the floor air supply,the indoor average temperature being about 25.6℃,The average air velocity of four way are within0.1 m/s.So for the capillary radiant air conditioning system,it is recommended to put the air supply outlet underside and floor.But in the work zone,temperature gradient of the underside air supply being about 1.3℃/m,compared with other forms being 0.44 ℃/m,is too large.Considering increasing the indoor design temperature about 0.5℃ when choose the floor air supply,achieving energy saving effect,it is suitable for handling the building of large cooling load.(4)By analyzing the load ratio undertaken by the capillary system,the results is that the indoor average temperature and temperature gradient decrease with the increasing of the proportion of the load undertaken by the capillary system.And the load ratio of capillary end increased by 10%, the average indoor temperature is reduced by about 1 ℃.So the optimal load ratio undertaken by the capillary system is around 60%.Generally,it is recommended that the load ratio undertaken by the capillary system remains within the range of 50% to 70%.To summarize,with the help of Airpak software,it is proved that capillary radiant air conditioning system can provide a very comfortable indoor thermal environment,the proposed design method in this paper is reasonable. Taking the displacement ventilation as the fresh air system,outlet arrangement and the load ratio undertaken by capillary terminal system are the important factors that affect the indoor thermal environment.There are 87 pictures,19 tables and 66 references in the master’s thesis.