Experimental studies on the air distribution with ceiling linear diffusers in a room

Nowadays, the application of the ceiling linear diffuser becomes very popular in office rooms due to the advantages of the silent operation and the efficient arrangement for the open plan office. However, one of the problems for the producer of the air diffuser and designer of the ventilation and air conditioning system is to determine and specify correctly the throw-length data in order to achieve optimal air movement in the occupied zone. Here, the comprehensive experimental studies were conducted to identify the variation characteristics of the jet throw-length using the ceiling linear diffuser. Totally fourteen cases including seven aspect ratios were measured under the isothermal conditions in a climate chamber with the dimensional size of 10 m *6 m *3.7 m equipped with the automatic measurement system. The results show that the critical aspect ratio regarding to 2D and 3D jet flow differs from the default value, 40, used to predict the jet throw-length by the present design guidebook. The results also confirmed that the jet maximum velocity decay coefficient depends on the details of the diffuser and thus should be identified for each kind of products. The presented methodology suggests a standard process to determine the maximum jet velocity decay coefficient.