Why is variable Vi added to a screw compressor?

Variable Vi is added to a screw compressor primarily to match actual operating conditions and minimize the effects of over-compressing or under-compressing the discharge gas. By allowing for adjustments in the compressor's internal geometry, variable Vi helps optimize the compression process for varying loads and conditions. This means that the compressor can adapt to changing requirements, leading to improved energy efficiency and reduced losses associated with compressing a gas that is either above or below the optimal conditions.

The ability to adjust the compression ratio dynamically contributes to maintaining performance levels and improving the overall efficiency of the system, ensuring that the compressor operates effectively across a range of applications.