Application Study Of A New Air Conditioning System Which Is A Combination Of Radiant Floor Cooling And Displacement Ventilation System

Emphasis is placed upon a new air conditioning system which is a combination of radiant floor cooling and displacement ventilation system in this paper. Some aspects reported in detail, such as system form, design feature, technical characteristic, thermal comfort, energy conservation and so on.Experiments have been performed under summer condition in radiant floor cooling laboratory in Nanjing PPW co.,LTD. A detailed account of the laboratory and test equipment was introduced in this article. Three comparison experiments were carried on under the uniform outside condition: radiant floor cooling experiment, displacement ventilation experiment and experiment combined radiant floor cooling with displacement ventilation. The whole experiments lasted for 109 hours. In these tests, indoor temperature filed include inner surface temperature of enclosing structure and dissipation energy of the system was recorded every hour, with experimental data handling, comparisons were discussed on these aspects: floor temperature and the air dew point temperature varied with time, inner surface temperature of enclosing structure varied with time, indoor temperature gradient varied with time and dissipation energy of the system varied with time. Some parameters such as Indoor radiation heat transfer, convective heat transfer, MRT, OT, radiation heat transfer coefficient, convective heat transfer coefficient, and PMV-PPD were calculated under a steady condition. From the result, we can conclude, when operation under the combination system and worst-case test, if floor temperature is about 21℃, supply air temperature is 21℃, air velocity is 1m/s, the equivalent coefficient of heat transfer between floor temperature and OT is 13.6w/m~2k, where 5.68w/m~2k is equivalent coefficient of radiant heat transfer, 9.48w/m~2k is convective heat transfer coefficient. And when air velocity is higher, supply air temperature is lower, the radiant heat transfer between floor and others is lower. In the whole experiment, the floor temperature was keeping above the indoor air dew point, and condensation was not appeared. Indoor temperature gradient between 0.1m and 1.1m was less then 3℃, meanwhile, increasing the supply air temperature properly can improve the thermal comfort further more. From the energy saving aspect, energy consume in water system is far below the air system, so using the radiant floor cooling system to remove the most cooling load also reflect energy conservation.In addition, a model of the combined system was developed, use the software Airpak to simulate indoor air temperature filed. The validity of the model was verified by experimental data. Based on this, the supply air temperature and air velocity was adjusted, and then give the optimum work condition.