The Study On U-Type Capillary Mats Ceiling Radiant Cooling Systems

As a low energy consumption and high comfort new air conditioning system, capillarymats ceiling radiant cooling system has been researched more and more extensive and intoengineering applications. But it also encountered in the actual promotion of a number ofbottlenecks. The main problems are condensation problems, lacking of cold capacity andone-time investment issues. When the surface temperature of the radiation panel is belowthe indoor air dew point temperature, condensation may appear, and thus the coolingcapacity of the radiant panel is restricted and one-time investment was lead to an increase.Factors affect the cooling capacity of the capillary mats radiant mainly containsstructural factors, operational factors, indoor environment temperature, etc. This article ison the study of the effects of the capillary mats radiant cooling capacity for structural andoperational factors, with the establishment of a three-dimensional fluid-solid couplingmodel of the U-type capillary mats plaster radiation panel, simulated the surfacetemperature distribution of the panel by changing parameters of mats length, tube spacingand gypsum thickness under same operating condition with numerical simulation softwareFluent, in order to find out key structural factors that affect the performance of the radiationpanel’s cooling capacity. Then through a large number of simulation, explore the structureparameters or scope of the radiant panel that can help to improve cooling capacity; On thisbasis, research the water temperature, water flow rate and other factors affect the coolingperformance of the gypsum radiant panel. The simulation studies show that:(1) Structuralfactors. Cooling capacity per area of the U-type capillary mats gypsum radiant panelreduced with the increase of tube spacing and gypsum thickness, the increase of the matslength has little effect on the cooling capacity of the panel. Boundary conditions of the sideof the panel also have some impact on panel cooling capacity.(2) Operational factors.Cooling capacity per area of the U-type capillary mats gypsum radiant panel reduced withthe increase of the supply water temperature, changing of the water flow rate has littleeffect on the cooling capacity of the panel. In addition, the total cooling capacity of thecapillary mats gypsum radiant panel increases with the improvement of interior designtemperature.A capillary mats ceiling radiant cooling air-conditioning system bench has been built,U-type capillary mats gypsum radiant panel has been made into a modular structure, liftedon the ceiling of the experimental chamber, using radiant ceiling plus displacementventilation/affixed jet mode, controlled through LabVIEW program automatically withcondensation control prioritized. The temperature distribution on the surface of the radiantpanel and in the room were tested of the U10type capillary mats gypsum radiant panel in different supply water temperatures and air supply forms; the differences on surfacetemperature distribution and the cooling effect between the U-type capillary mats gypsumradiant panel and the U-type capillary mats metal radiant panel under the same testconditions were compared. Experimental results show that: The uneven surface temperaturedistribution of the metal panel is smaller than the gypsum panel; tube density has a greatimpact on radiant cooling capacity. Cooling capacity of the radiant panel can be improvedby reducing supply water temperature. Water temperature should be adjusted according tothe indoor load when there is no risk of condensation; metal capillary mets radiant panelhas a rapid response at room temperature control compared with the gypsum radiant panel.Under same conditions, the room installing metal panel can reach set temperature tenminutes earlier than that installing gypsum panel. Metal radiant panel reacted more rapidlywhen supply water temperature changes and could achieve good control accuracy. Gypsumradiant panel has the ability of cold storage compared with the metal panel, and can releaseresidual cold to the room at night, making the room temperature rises slowly. Simulationresults and experimental results agree well. The result from this study can provide atheoretical basis for the system design as well as further research to the capillary radiantcooling systems.