Mechanical Engineering - Compressors, Gas Dynamics and Gas Turbines - Discussion

Why? Explain.

Temperature is slightly high and pressure is slightly low when compared to the atmospheric condition when air enters the compressor.

Common compressors are naturally aspirated displacement compressors. This means that the intake air is entering the compressor at ambient air pressures and the compressor is raising the pressure by reducing a volume of air by a fixed amount. The amount of air compressed is dependent on the density of the air entering the compressor which correlates to the temperature of the air. If the air temperature rises, the density decreases. If the intake air temperature is higher there is less air entering the compressor because it can only intake a fixed volume of air.

During suction stroke it is a free expansion process, so dt=0. Then why can't it be equal to atmospheric temperature?

It is given that at the beginning of compression stroke, that means the air is already in the cylinder, so the air draws certain temp from the cylinder walls and piston.

@Ashok Aj.

At the beginning of the compressor, even the walls and piston is at atmospheric conditions.

I think the temperature is low.