Impact of the method of air suction on the energy efficiency of fan systems

The paper presents methods for improving the energy efficiency of fan systems using elements installed at the inlet of the suction pipe, in order to smoothly reduce the air flow to the relevant pipe sizes. Two cases are studied - when the suction is performed from "Unlimited space", as well as from limited space in the presence of a transverse wall. An indicator (coefficient kE) used to quantify the rate of improvement of the system energy efficiency by installing a suction element, evaluating what part is the particular improvement of energy efficiency based on the air suction pressure losses without installing an inlet body for improving suction, has been established. When using a suction cone, it is recommended that the taper angle be about 60o and a relative length L /D of not less than 0.2. Under these conditions, the reduction in inlet pressure losses is up to 0.9 compared to those without a suction cone installed. When using a smooth inlet, it is recommended that the relative radius should be R/D>0.1. For both studied methods of suction (from an unrestricted medium and from a transverse wall) the coefficient kE has values around 0.9.