High delivery pressure strategy: best choice of compression arrangement When very high delivery pressure is required, which arrangement is most advantageous for air compression from the viewpoints of work and temperature control?

Introduction / Context:
Achieving high discharge pressures efficiently requires attention to both thermodynamics and component limits. Excessive discharge temperatures damage lubricants and valves, while high work input raises operating costs.

Given Data / Assumptions:

• Need for high overall pressure ratio.
• Conventional air compressor hardware (reciprocating or rotary positive-displacement).
• Cooling available between stages.

Concept / Approach:
Splitting compression into multiple stages reduces work when intercooling is provided between stages. Intercooling removes heat, reduces specific volume before the next stage, and keeps metal and discharge temperatures within safe limits. The minimum total work occurs when pressure ratios per stage are equal and intercooling is near-perfect.

Step-by-Step Solution:

Verification / Alternative check:
Analytical expressions for polytropic compression show reduced enthalpy rise per kilogram with intercooling; practical experience confirms improved valve life and lubricant stability.

Why Other Options Are Wrong:

Single-stage: excessive discharge temperature and high work at large pressure ratios.Multistage without intercooling: forfeits much of the work-saving benefit.Large clearance or oversized motor do not change the unfavorable thermodynamics.

Common Pitfalls:
Confusing aftercooling (after final stage) with intercooling (between stages); only intercooling reduces subsequent stage work.

Final Answer:

Multistage compression with intercooling