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Re: USA 250-256 [Spoiler Alert: Engineering/Thermodynamics Content]

February 01, 2014 10:55AM avatar
Tom, I too was confused by rehunn's post. Superheat improves the thermal efficiency of ANY vapor cycle. Your comments regarding superheat increasing volume are true...but that isn't the reason it is more efficient. Let's look at a sample thermodynamic cycle for an engine with superheat:

Rankine_cycle_with_superheat.jpg

Notice that all heat addition is essentially a constant-pressure process. Heat addition increases the energy in the fluid which is manifested through an increase in temperature and entropy (s) once you are in the vapor state. The perfect gas law indicates V=nRT/P so when all else is constant, an increase in T results in an increase in V, validating your comment. However the real increase in power and efficiency comes from the basic fact that we have extracted more energy from the "fire" and have more available energy in the fluid to do work.
Subject Author Posted

USA 250-256 Attachments

Everett Lueck January 30, 2014 08:58PM

Re: USA 250-256

Tom Moungovan January 30, 2014 09:25PM

Re: USA 250-256

m.j.peltier January 30, 2014 09:56PM

Re: USA 250-256

J.B.Bane January 31, 2014 10:20AM

Re: USA 250-256

Tom Moungovan January 31, 2014 02:09PM

Re: USA 250-256

rehunn January 31, 2014 03:19PM

Re: USA 250-256

GeorgeGaskill January 31, 2014 05:00PM

Re: USA 250-256

Tom Moungovan January 31, 2014 06:34PM

Re: USA 250-256 [Spoiler Alert: Engineering/Thermodynamics Content] Attachments

rainbowroute February 01, 2014 10:55AM

Re: USA 250-256 [Spoiler Alert: Engineering/Thermodynamics Content]

rehunn February 01, 2014 04:29PM

Re: USA 250-256 [Spoiler Alert: Engineering/Thermodynamics Content]

Tom Moungovan February 01, 2014 08:28PM

Re: USA 250-256 [Spoiler Alert: Engineering/Thermodynamics Content]

Everett Lueck February 01, 2014 09:13PM

Re: comments to Everett

Tom Moungovan February 02, 2014 01:44AM

Re: comments to Evereett Attachments

Everett Lueck February 02, 2014 08:23AM

Re: comments to Evereett

m.j.peltier February 02, 2014 06:23PM

Re: comments to Evereett

John C May 21, 2014 05:45PM

Three lok trains up the hill

m.j.peltier May 23, 2014 01:06PM

Re: duplicate post-deleted

Tom Moungovan January 31, 2014 06:34PM

Re: duplicate post-deleted

rehunn February 01, 2014 09:15AM

Re: USA 250-256

Jim Grigsby February 01, 2014 12:20PM

Re: USA 250-256

John C May 21, 2014 05:41PM

Re: 190 class gauge

m.j.peltier May 23, 2014 01:11PM

Re: USA 250-256

John C February 04, 2014 02:51PM

Re: USA 250-256

whitepasser February 09, 2014 12:50AM

Re: WP&YR 69

m.j.peltier May 23, 2014 01:15PM

Re: USA 250-256

John C May 23, 2014 03:54PM

Re: USA 250-256

John C May 24, 2014 01:52PM



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