# Indicated power of air compressor and power of electric power machine

The required power of the air compressor can be determined by calculation according to the theoretical process occurring in air compressor (when calculating with isothermal and adiabatic compression, appropriate correction shall be made to the actual cycle), or the indicator diagram drawn when testing the air compressor with the experimental square root saw.

These two methods are respectively used in the calculation and test of air compressor, and the latter gives the least error.

When calculating the power of the air compressor, it is most reasonable to calculate the adiabatic compression, because in this case, the compression ratio of the air compressor has the least influence on the deviation between the calculated result and the actual power.

When adiabatic compression, the actual or indicated power consumed in the air compressor cylinder is determined according to the following formula: **Ni = Nm / Nn**

In the formula,

Nm :theoretical power of air compressor, kW; m= x = 1.4;

Nn: adiabatic indicating efficiency of air compressor, which is used to consider the deviation between theoretical cycle and actual cycle, with an average of 0.9-0.94.

**Shaft power of air compressor: N6 = N4 / NW**,

NW -- mechanical efficiency of air compressor, which is generally 0.85-0.95, is used to consider the mechanical resistance from the piston to the main shaft of air replacement piston refrigeration compressor.

In order to determine the indicated power, the area of the indicated power diagram is first calculated with a planimeter, and then the height h I of the rectangle with the length of Li and the area equal to the area of the indicated power diagram is determined.

For air compressor equipment, only in terms of compressed air, the annual electricity consumption in the air compressor station is calculated by the following formula:

The unit electric energy consumption spent on cooling water supply depends on the characteristics of air compressor structure, that is to say, the cooling water consumption and water supply height required for 1 m 3 air compressor suction.

The unit electric energy consumption spent on the water required for compressed air cooling is determined according to the following formula:

Reciprocating air compressor compresses the unit electric energy consumption of 1 m ~ 3 air, and the unit electric energy consumption spent on cooling water supply to air compressor can be taken as 0.6-0.8 kW per hour / 1000 m ~ 3.