The performance of backward curved centrifugal fan with various impeller inlet and outlet angles

The backward curved centrifugal fan is the main component in air duct flow system. The fans consume approximately 15% of building energy consumption, therefore their efficiency critically impacts the energy demand and cost. The performance of a fan is determined by a number of design factors. In this study, the effect of the impeller's inlet and outlet angles on the fan performance was investigated using the CFD flow simulation. An experimental data was also collected from a model fan following the ISO 5801 standard for comparisons. Based on simulation results, an increase in the outlet angle from 30° to 40° at a constant inlet angle led to a higher air power (approximately 11%), whereas an increase in the inlet angle from 15° to 21° at a constant outlet angle causes minimal change to the air power (less that 0.4%). As the air power is related to the fan efficiency, the results have an implication on the design and manufacturing of a fan to ultimately lower the energy requirements in buildings.