Cen54261ch07qxd 111803 957 am page 304 304

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: elative to its critical-point value of 450°F. Therefore, the isentropic relations developed earlier for ideal gases are applicable. T, R P2 T2 = 780 R P2 = ? 780 2 Isentropic compression He COMPRESSOR 4 psia P1 = 1 510 1 P1 = 14 psia T1 = 510 R s FIGURE 7–40 Schematic and T-s diagram for Example 7–11. cen54261_ch07.qxd 11/18/03 9:57 AM Page 304 304 FUNDAMENTALS OF THERMAL-FLUID SCIENCES Analysis The specific heat ratio k of helium is 1.667 and is independent of temperature in the region where it behaves as an ideal gas. Thus the final pressure of helium can be determined from Eq. 7–43: P2 7–10 I P1 T2 T1 k/(k 1) (14 psia) 780 R 510 R 1.667/0.667 40.5 psia REVERSIBLE STEADY-FLOW WORK The work done during a process depends on the path followed as well as on the properties at the end states. Recall that reversible (quasi-equilibrium) moving boundary work associated with closed systems is expressed in terms of the fluid properties as 2 Wb P dV 1 We mentioned that the quasi-equilibrium work interactions lead to the maximum work output for work-producing devices and the minimum work input for work-consuming devices. It would also be very insightful to express the work associated with steadyflow devices in...
View Full Document

This document was uploaded on 11/28/2012.

Ask a homework question - tutors are online