| Variable air volume systems have been widely used in various kinds of buildings due to their energy-savings, comfort, safety and good flexibility. Because the basic principle of Variable air volume system is to meet the comfort conditions indoor by varying air flow rates, air distribution is rather important. The proper selection of air diffusers will help to ensure that variable air volume will operate over a range of air volumes well. As air distributor in a variable air volume system, the performance of slot diffuser is the best one, but the type of diffuser is too expensive, so at home many firms try to choose square diffuser.In the paper, we made initial studies on whether square diffuser could be used in variables air volume in a cooling mode. We firstly predicted and analyzed air distribution of test room with three different ways, and then made experimental study. The experiment was conducted in a test room with a variable air volume. We used anemometers and copper constantan thermocouple respectively to measure velocities and temperatures of all measuring points under various air volumes within the room. In addition, in order to know the direction of air currents well, we made filament experiment.Based on those experimental data, we adopted TECPLOT software to visualize all those temperature profiles and velocity profiles and made further analysis. Meanwhile, we adopted air distribution performance index, temperature gradients and average velocity to evaluate and compare room air distribution under various air volumes.Through thorough analysis, we finally drew that on condition of experiment, square diffuser could ensure good air distribution when air supply volumes ranged from 40 to50 percent or 80 to 100 percent of the maximum air supply volumes. When air supply volumes ranged from 50 to 80 percent of the maximum air supply volumes, square diffuser could not be very ideal with a variable air volume in a cooling mode. |
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