616 eq 624 dqrev dh dp substituting this into the

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: terms of fluid properties. Taking the positive direction of work to be from the system (work output), the energy balance for a steady-flow device undergoing an internally reversible process can be expressed in differential form as dqrev dwrev dh dke dpe But qrev T ds T ds dh υ dP (Eq. 6–16) (Eq. 6–24) dqrev dh υ dP Substituting this into the relation above and canceling dh yield dwrev υ dP dke dpe Integrating, we find 2 wrev 1 υ dP ke pe (kJ/kg) (7–51) When the changes in kinetic and potential energies are negligible, this equation reduces to 2 wrev 1 υ dP (kJ/kg) (7–52) Equations 7–51 and 7–52 are relations for the reversible work output associated with an internally reversible process in a steady-flow device. They will give a negative result when work is done on the system. To avoid the negative cen54261_ch07.qxd 11/18/03 9:57 AM Page 305 305 CHAPTER 7 sign, Eq. 7–51 can be written for work input to steady-flow devices such as compressors and pumps as 2 wrev, in 1 υ dP ke pe (7–53) The resemblance betwee...
View Full Document

This document was uploaded on 11/28/2012.

Ask a homework question - tutors are online