Unit No:02Energy Conversion Devices

Prof. Yash B. ParikhM.Tech (Computer Integrated Manufacturing)

B.E.(Mechanical Engineering)Assistant Professor

Department of Mechanical Engineering

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Blowers

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Blowers A centrifugal blower is similar in construction

to that of centrifugal compressor. Except the fact that blowers doesn’t have

diffuser blades installed.

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Blowers Air is sucked in the impeller eye and due to

centrifugal action it passes over impeller vanes.

The static pressure of air is increased from the eye to the tip of the impeller.

The high velocity air leaves through the volute casing.

In blowers the pressure rise is less than the centrifugal compressor but has the high exit velocity and discharge volume rate.

Used where high pressures are not needed, but high velocity of air at discharge is required.

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Fans Most manufacturing plants use fans for

ventilation and for industrial processes that need an air flow.

Fan systems are essential to keep manufacturing processes working.

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Fans Fans are provide air for ventilation and

industrial process requirements.

Fans generate a pressure to move air (or gases) against a resistance caused by ducts, dampers, or other components in a fan system.

The fan rotor receives energy from a rotating shaft and transmits it to the air.

Fans develop vey low pressures compares to blowers and compressors.

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Fans, Blowers & Compressors

Fans, blowers and compressors are differentiated by the specific ratio, which is the ratio of the discharge pressure over the suction pressure.

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Types of Fans

There exist two main fan types.

Centrifugal fans : a rotating impeller is used to move the air stream.

Axial fans : the air stream is moved along the axis of the fan.

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Types of Fans

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Types of Centrifugal Fans There are three types of centrifugal fans,

based on the inclination of the fan blades.

These are,1. Forward curved blade : here the blades are

fixed such that tip of blade tilts towards the direction of rotation.

2. Radial blade : here blades are fixed radially, without any curvatures.

3. Backward curved blade : here tip of the blade tilts in the opposite direction to rotation.

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Types of Centrifugal Fans

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Types of Axial Fans

There are three types, Tube axial :• These fans have a wheel inside a cylindrical

housing, with close clearance between blade and housing to improve airflow efficiency.

• The wheel turn faster than propeller fans, enabling operation under high-pressures.

• The efficiency is up to 65%.

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Types of Axial Fans Vane axial fans : • They are similar to tube axial fans, but with

addition of guide vanes that improve efficiency by directing and straightening the flow.

• As a result, they have a higher static pressure with less dependence on the duct static pressure.

• Vane axial fans are typically the most energy-efficient fans available and should be used whenever possible.

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Types of Axial Fans Propeller fans : They usually run at low speeds and moderate

temperatures. They experience a large change in airflow with

small changes in static pressure. They handle large volumes of air at low

pressure. Propeller fans are often used in indoors as

exhaust fans. Outdoor applications include air-cooled

condensers and cooling towers. Efficiency is low – approximately 50% or less.

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Types of Axial Fans