Numerical Research On Radiant Air-conditioning System Based On Air Carring Energy Technique In Large Space

Due to the features of large space buildings with large space load, complex airdistribution, it is difficult to ensure both the thermal comfort in air-conditioning areaand the energy efficiency simutaniously. To some extent, a radiant air-conditioningsystem based on air carring energy principle solves the problems of moisturecondensation as well as the insufficient cooling capacity of a conventional radiationsystem in summer time. The advantage of this newly developed system can besummarized as: high thermal comfort, energy saving and anti-condensation. Theperformance of heat transferring of the therminal panels and the dew point of the airnear the panles were firstly studied. It can be seen that the cooling capacity of thissystem can satisfy the cooling load in large space. And then, the feasibility ofapplying the radiant air-conditioning system based on air carring energy techniquewas studied by using FLUENT. In this article, specific work is listed as follows:Firstly, the performance of radiation heat transfer this system was studied. Basedon the basic principles of heat transfer,, the radiation heat transfer coefficientbetween orifice plate and the surrounding airwas analyzed under different apertureratio and orifice plate temperature (summer:15℃,20℃, winter:30℃,35℃).Eventually asimplified formula of radiation heat transfer of radiant air-conditioningsystem based on air carring energy technique was abtained, and then the rationality ofthis formula is verified by experimental results.Secondly, qualitative analysis of the critical dew point temperature near theterminal orifice plate surface was applied. By establishing the system model, the roomair-conditioned area is assumed to be with constant temperature and humidityenvironment (tn=28℃,φn=65%). The suppliedair relative humidity is assumed tobe constant (φs=95%), and the orifice plate temperature was controlled independently.These boundary setup was applied for simulations, and results were obtained underdifferent supplied air temperature (ts=6,8,10,12,14℃), air velocity (v=0.5,1.0,1.5,1.0m/s) as well as the aperture ratio (k=0.5%,1.0%,1.5%) corresponding to thecritical dew point temperature of the orifice plate. The general distributions of thecritical dew point temperature on terminal orifice plate can be reached. It can beconcluded that the cooling performance of the radiation system is satisfying. And thensimulation of large space buildings applying this system was conducted.Finally, the radiant air-conditioning system based on air carring energy technique combined DOAS system was simulated by FLUENT in a station space. The waitingarea temperature, relative humidity, flow streams, pressure distribution and heattransfer features were analyzed. The results show that the temperature and humidityinside the waiting area meets the design requirements, and there is on condensationoccurring on orifice plate surface. A92.9%cooling load for the waiting area wasprovided by this systme, and the radiation coolingaccounts for64.2%of the totalcooling load, while DOAS system takes only7.1%of the total cooling load. Resultsshows that radiant air-conditioning system based on air carring energy technique cansatisfy the cooling load during simmer time in large space. Applying a radiantair-conditioning system based on air carring energy technique to large space ispossible based on above analysis, and this study provides a reference for futureapplication design.