# It is a good thing that it is not otherwise heat

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

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

Unformatted text preview: rk is not zero. (It is a good thing that it is not. Otherwise, heat engines that work on a cycle such as steam power plants would produce zero net work.) Neither is the cyclic integral of heat. Now consider the volume occupied by a gas in a piston-cylinder device undergoing a cycle, as shown in Fig. 7–2. When the piston returns to its initial position at the end of a cycle, the volume of the gas also returns to its initial value. Thus the net change in volume during a cycle is zero. This is also expressed as dV 0 (7–3) That is, the cyclic integral of volume (or any other property) is zero. Conversely, a quantity whose cyclic integral is zero depends on the state only 1 m3 3 m3 1 m3 ∫ dV = ∆V cycle =0 FIGURE 7–2 The net change in volume (a property) during a cycle is always zero. cen54261_ch07.qxd 11/18/03 9:57 AM Page 276 276 FUNDAMENTALS OF THERMAL-FLUID SCIENCES and not the process path, and thus it is a property. Therefore, the quantity (dQ/T)int rev must represent a property in the diff...
View Full Document

## This document was uploaded on 11/28/2012.

Ask a homework question - tutors are online