Thermal Engineering Unit II - Air Compressors

Compressors in which air is compressed in sealed spaces or between two engaging surfaces are called

• Rotodynamic compressors

• Centrifugal compressors

• Positive Displacement compressor

• Axial flow compressors

Choose the positive displacement compressors among the following (Multiple answers)

• Reciprocating Air Compressors

• Vane compressors

• Lobe compressors

• Centrifugal Compressors

Which one of the following is a rotary roto-dynamic compressor

• Vane Compressor

• Centrifugal Compressor

• Screw compressor

• Lobe Compressor

Which of the following process will require minimum work during compression of air

• Polytropic compression

• Isentropic compression

• Isothermal compression

• Isochoric compression

Isothermal efficiency of a reciprocation air compressor is defined as

• The ratio of isothermal work to actual work

• The ratio of actual work to isothermal work

• The ratio of isohermal work to isentropic work

• The ratio os isentropic work to isothermal work

The volumetric efficiency of a reciprocating compressor is defined as the ratio of

• the swept volume to actual volume of air intake in a cycle

• the swept volume to clearance volume

• actual volume of air intake in a cycle to swept volume

• the clearance volume to swept volume

Volumetric efficiency of a reciprocating air compressor

• increases with pressure ratio

• decreases with pressure ratio

• remains constant with change in pressure raito

• increases and then decreases with pressure ratio

Multi-stage compression with intercooling

• reduces work input

• increases volumetric efficiency

• helps in better lubrication

• All of the above

Power input required in a reciprocating air compressor

• depends on clearance volume

• is independent of clearance volume

• increases with clearance volume

• decrease with clearance volume

FAD is defined as

• The volume of air handled by the compressor per cycle reduced to atmospheric conditions

• The volume of air handled by the compressor per unit time reduced to suction conditions

• The volume of air handled by the compressor per unit time reduced to atmospheric conditions

• The volume of air handled by the compressor per cycle reduced to suction conditions