Subject:- Refrigeration and Air Conditioning

Topic:- Duct Design and Applications

Difficulty:- Medium

Aspect Ratio

It is defined as the ratio of long side (a) to the short side (b) of a rectangular duct.

A.R.=$\frac{a}{b}$

Aspect ratio is the major factor which influences initial and running cost of a duct. As A.R. increases, the heat gain by duct also increases. If A.R. increases for the fixed duct area and capacity, the weight of duct material and weight of insulation also increases.