RevisionC-Developmentofconceptofcompressorforcommercialvehicle

Process Description
Figure 1:7: p-V diagram for a reciprocating compressor with clearance
c-d: Expansion stroke: -
Piston begins the induction stroke. The compressed air occupying the clearance volume
expands according to the polytropic law until p and T reduce to p1 & T1. Ideally, no heat transfer
from air to the surrounding.
d-a: Induction stroke: -
Inlet valve open. Fresh air is induced into the cylinder at constant p & T. The volume of
air induced is Va–Vd. No heat transfer from air to the surrounding.
a-b: Compression stroke: -
Both valves closed. Induced air is compressed according to pVn=c, until the pressure
and temperature increases to p2 and T2. No heat transfer from air to the surrounding.
b-c: Delivery stroke: -
The exhaust valve opens. The compressed air is delivered out at constant pressure p2
and T2. No heat transfer from the air to surroundings. Air Compressors with Clearance.
Note: At the end of the delivery stroke, the clearance volume is filled with compressed air at p2
and T2. The cycle is then repeated.
1.1.2.5 Multistage Compressor
The air is compressed in more than one cylinder (or stage) to the desired pressure, p2.
After the first stage of compression, the fluid is passed into a smaller cylinder in which the gas is
compressed to the required final pressure. If the machine has two stages, the gas will be
delivered at the end of this stage, but it also could be delivered to a third cylinder for higher
pressure ratio.
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