Research On The Equipment Of Terminal Heat Transfer In Radiation Air-conditioning

At present, there are two kinds of terminal equipment of radiation air-conditioningin the market. One is cooling ceiling and the other is capillary radiation tube that isapplied widely in engineering practice. However, not only is capillary radiation tubeexpensive, but also low in cooling capacity and easy to condensation. Considering thecost of production, engineering application, cooling capacity and space comfort, twokinds of radiant panel were designed in the present. The capillary wick radiant panelwas designed with water, gypsum and a little amount of potassium citrate as the rawmaterials. The parallel flow radiant panel was designed with parallel rectangularchannel （3mm in width and1.5mm in height） at space interval of3mm in the ABS plate.Refrigerant and chilled water are used as the common secondary refrigerant in theterminal device of air-conditioning. And there are two kinds of radiationair-conditioning designed in the program of exeperiment. Frist, the single stagevaporizing capillary wick radiation air-conditioning system was designed by usingcapillary wick radiant panel as the evaporator and C5H12as the refrigeration inlaboratory. Meanwhile, the parallel flow radiant panel air-conditioning system wasdesigned by using parallel flow radiant panel as the radiation surface and chilled wateras the refrigerant.Based on the analysis of the single stage vaporizing capillary wick radiationair-conditioning system, the loss of Ex,h、COP and η were studied systematically andthe influence of evaporative temperature and the space temperature in model on coolingcapacity and the loss of Ex,hwere also researched The results indicate that theradiation air-conditioning system have advantages of the increased cooling capacity andthe reduced condensation. Meanwhile, in order to analysis resistance character ofradiation panel of capillary wick, a new resistance model of the flow of two phases wasestablished. Based on the model, the effect of flow on resistance and the influence of Reon f were studied. The f in the experiment has been high consistency to Blassius’ssolution: f=0.079Re^-0.25.Furthermore, capillary radiation air-conditioning system was used as a contrast theparallel flow radiant panel air-conditioning system was studied by using the water withtemperature of17℃²5℃respectively. The cooling capacity, distribution oftemperature in the space and the effect of space temperature on the cooling capacity were discussed. The results show that: not only can the parallel flow radiant panelprovide larger cooling capacity, but also provide better comfortable space than thecapillary radiation air-conditioning system. Meanwhile, the transition Re and f in themicro-channel were studied through changing the inlet and export flow in the bothradiation panel. The results of study show that the transition Re is lower in themicro-channel than conventional pipe, which is about800⁹00. In the experimentalrange, the f in micro-pipe of parallel flow radiation panel is approximately equal to the faccording to calculation of the classical formulaf=64/Re.Compared with the conventional split type air conditioning system, single stagevaporizing capillary wick radiation air-conditioning system can reduce E_x,H about60%in terminal equipment of heat transition and contrast to the fan coil unit system, parallelflow radiant panel system can reduce E_x,H about80%in terminal equipment of heattransition. Combined with cooling capacity and the requirement of radiation airconditioning design, the optimum flow is41.3L/h in the radiation panel with parallelchannels. Based on this, the loss of E_x,H and the influence of cooling capacity on the lossof E_x,H were studied. And the three characters including flow、the loss of E_x,H andcooling capacity were compared under the optimum flow, the results show that radiationpanel with parallel channels have some advantage of saving flow, reducing the loss ofE_x,H and improving cooling capacity.