Cooling performance of radiant air conditioning with an infrared-transparent membrane

In view of the problems that the surface of radiant air conditioning is prone to condensation and the cooling capacity is limited by the dew-point temperature, a model for radiant air conditioning with an infrared-transparent membrane has been developed which installs an infrared-transparent membrane vertically below the radiant cooling plate of a radiant air conditioner to form a closed gas interlayer between them. On the basis of this, the effects of the gas type (vacuum, nitrogen, air, argon, and carbon dioxide) and relative air humidity in the interlayer on the radiative heat transfer, convective heat transfer, and radiative heat-transfer ratio of the radiant cooling plate, and the surface temperature of the infrared-transparent membrane were investigated by CFD (Computational Fluid Dynamics) numerical simulation. When the thickness and gas type of the interlayer were 20 mm and vacuum, respectively, the radiant cooling plate showed the most radiative heat transfer, the least convective heat transfer, the largest radiative heat-transfer ratio, and the highest surface temperature of the membrane, followed by when the gas type was argon. There was no risk of condensation in the air conditioning when the relative air humidity in the interlayer did not exceed 80%. The results of the study provide a theoretical basis for the optimal design of radiant air conditioners.