Thermodynamics filled in class notes_Part_9

Thermodynamics filled in class notes_Part_9 - 2.2 EXERGY 25...

This preview shows pages 1–2. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

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

Unformatted text preview: 2.2. EXERGY 25 h + (1/2) v v + g z h + gz o . q = - q cv H,Carnot q L,Carnot w Carnot Carnot Engine T o o Control Volume Figure 2.2: Sketch of control volume balance for exergy discussion. Now take the “in” state to be simply a generic state with no subscript, and the “out” state to be the reference state, so 0 = ˙ Q cv − ˙ W cv + ˙ m parenleftbigg h − h o + 1 2 ( v · v ) + g ( z − z o ) parenrightbigg . (2.81) Let us next scale by ˙ m so as to get 0 = q cv − w cv + h − h o + 1 2 v · v + g ( z − z o ) . (2.82) Here we have taken q cv ≡ ˙ Q cv / ˙ m and w cv = ˙ W cv / ˙ m . Now, let us insist that w cv = 0, and solve for q cv to get q cv = − parenleftbigg h − h o + 1 2 v · v + g ( z − z o ) parenrightbigg . (2.83) Now, we imagine the working fluid to be at an elevated enthalpy, velocity, and height relative to its rest state. Thus in the process of bringing it to its rest state, we will induce q cv < 0. By our standard sign convention, this means that thermal energy is leaving the0....
View Full Document

This note was uploaded on 11/26/2011 for the course EGN 3381 taught by Professor Park-sou during the Fall '11 term at FSU.

Page1 / 2

Thermodynamics filled in class notes_Part_9 - 2.2 EXERGY 25...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online