Indoor Air Conditioning Unit Air Flow Performance Study – Characterization of Cross Flow Fan Designs

Abstract

A detailed characterization is carried out on a typical cross flow fan used in the Heating, Ventilation, and Air Conditioning (HVAC) industry, in order to understand the fan design in detail. The study is carried out numerically by use of the software FLUENT and followed by experimental validation. Appropriate grid size selection has done, the RMS error is less than 7%. From the study, it is concluded that the thickness of the blade determines the total flow area and flow rate delivered. When the internal blade angle is at 90°, shock free entry is incurred and maximum flow rate can be achieved. The external blade angle should be within 20 to 45 degrees, to avoid rapid drop of pressure coefficient and efficiency. Lastly, the formation of the eccentric vortex zone inside the cross flow fan and flow field pattern are observed. The forming location and size of the zone determines the total air flow rate delivered and the amount of flow leakage through the tongue. Thus, the efficiency of the fan is highly sensitive to the flow structure in this zone.