Intercooling in multistage compression reduces _______
Intercooling in multistage compression reduces the work input to compressor.
In multistage compression with intercooling, where the gas is compressed in stages and cooled between each stage by passing it through a heat exchanger called an intercooler.
Ideally, the cooling process takes place at constant pressure, and the gas is cooled to the initial temperature T1 at each intercooler.
In general, the intercooler is provided between the cylinders of the multi-stage compressor, for the purpose of cooling the compressed air to the original (inlet) temperature before entering the next stage.
Multistage compression with intercooling is especially attractive when gas is to be compressed to very high pressures.
P-V and T-S diagram of the compression with intercooling is shown in the figure below:
It can be seen that intercooling is done at constant pressure and is represented by a horizontal line on the P-V diagram.
If an intercooler is installed between cylinders, in which the compressed air is cooled between cylinders, then the final delivery temperature is reduced.
This reduction in temperature means a reduction in internal energy of the delivered air, and since this energy must have come from the input energy required to drive the machine, this results in a decrease in input work requirement for a given mass of delivered air.
By multi-staging, the pressure ratio of each stage is lowered. Thus, the air leakage past the piston in the cylinder is also reduced.
The low-pressure ratio in a cylinder improves volumetric efficiency.