The compressor work is decreased when two stages of

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: mp I, in 2 nRT1 Px n 1 P1 (n 1)/n 2(1.3)(0.287 kJ/kg · K)(300 K) 1.3 1 1 300 kPa 100 kPa (1.3 1)/1.3 1 215.3 kJ/kg Discussion Of all four cases considered, the isothermal compression requires the minimum work and the isentropic compression the maximum. The compressor work is decreased when two stages of polytropic compression are utilized instead of just one. As the number of compressor stages is increased, the compressor work approaches the value obtained for the isothermal case. 7–12 P1, T1 P1, T1 ACTUAL (irreversible) IDEAL (reversible) P2 P2 FIGURE 7–48 The isentropic process involves no irreversibilities and serves as the ideal process for adiabatic devices. I ISENTROPIC EFFICIENCIES OF STEADY-FLOW DEVICES We mentioned repeatedly that irreversibilities inherently accompany all actual processes and that their effect is always to downgrade the performance of devices. In engineering analysis, it would be very desirable to have some parameters that would enable us to quantify the degree of degradation of energy in these devices. In the last chapter we did this for cyclic devices, su...
View Full Document

Ask a homework question - tutors are online