Equation 76 is particularly useful for determining

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: le process. Equation 7–6 is particularly useful for determining the entropy changes of thermal energy reservoirs that can absorb or supply heat indefinitely at a constant temperature. Notice that the entropy change of a system during an internally reversible isothermal process can be positive or negative, depending on the direction of heat transfer. Heat transfer to a system will increase the entropy of a system, whereas heat transfer from a system will decrease it. In fact, losing heat is the only way the entropy of a system can be decreased. EXAMPLE 7–1 Entropy Change during an Isothermal Process A piston-cylinder device contains a liquid–vapor mixture of water at 300 K. During a constant-pressure process, 750 kJ of heat is transferred to the water. As a result, part of the liquid in the cylinder vaporizes. Determine the entropy change of the water during this process. T = 300 K = const. SOLUTION We take the entire water (liquid ∆Ssys = vapor) in the cylinder as the system (Fig. 7–4). This is a closed system since no mass crosses the system boundary...
View Full Document

This document was uploaded on 11/28/2012.

Ask a homework question - tutors are online