TABLE OF CONTENTS A fan is a device that moves gasses or vapors from one location to another. Since fans are usually low velocity devices the gas, which usually is air, can be considered to be incompressible for the majority of engineering calculations. The general characteristics of fan operation are the following:
Volumetric fan output varies directly with the fan speed of rotation for a given fan.
The pressure or head of the fan varies directly with the square of the speed of the fan.
The power required to run a given fan varies directly with the cube of the speed.
For a given installation and constant fan speed, the pressure output and the operating power required will be proportional to the density of the gas.
For a constant mass flow rate of gas, the fan speed, the volumetric output, and the pressure vary inversely as the density of the gas. In addition, the power required varies inversely with the square of the density of the gas.
At a constant pressure the speed, volumetric output and power vary inversely with the square root of the density of the gas.
Q:
A coal fired boiler requires 1,700 m 3 /min of air at a pressure of 15 cm of water for the combustion process. The fan has a mechanical efficiency of 58% at the given conditions. How large of a motor in kW is required to power this fan?
Answers
Q:
Generally we may conclude that fans are low pressure...
