Talk:Heat engine

message: The difference between Cycle type and engines needs to be split apart. The Diesil cycle can be run completely differently from the diesil engine. Ericsson created a Diesil cycle engine that ran on external combustion. The diesil cycle doesn't require diesil fuel and can have an air fuel mixture instead of fuel injection. The Otto Cycle can be either 2 or 4 stroke.Eric Norby
Would it be reasonable to add the tropical cyclone as another example of a heat engine? Presumably under the vapor power cycle heading.
Cyclones: I'm not an expert on cyclones, but I would guess it is roughly an example of one of the types already mentioned?  If anyone knows more about it, it's a good example to add. Mat-C 17:40, 10 July 2005 (UTC)
thread_title: difference between Cycle type and engines

message: This page appears to be a mishmash of highly technical discussion and lists.  The lists are incomplete and the technical discussion is mostly covered more usefully in other articles (such as carnot cycle). Would it be best to make this page a simple description with suitable off links to more detail; should we try to make the list complete; is it useful to have diagrams?
The article doesn't make the relationship between heat engines and heat pumps clear, and it doesn't make the point that all (almost?) energy transformations involve the carnot efficiency (e.g. batteries, solar panels, lights).
I'm happy to spend a while cleaning it up, but I am not getting an feeling for what really belongs here. njh 08:36, 4 February 2006 (UTC)
thread_title:  What is the purpose of this page? 

message: Nathan - I agree with your comments about this page.  I would propose a reasonable simple explanation of what a heat engine is, and relationship to a heat pump.  This article might refer to heat/work cycles in nature but I think the emphasis should be on man-made machines.  It would be good to have list of links to cycles, and also to pages referring to example machines.  Agree that it would be best to keep cycles and machines separate.
It would be great if this article could also be mirrored for heat pumps, which is also in need of some attention. mike 17:45, 17 March 2006 (UTC)
thread_title:  Agree - need for an overhaul 

message: I removed "photon cycle" and the only example listed under it, solar sail.  A solar sail operates by converting radiation pressure into mechanical energy.  That makes it a type of engine other than a heat engine. --Delirium 06:30, 10 September 2006 (UTC)
thread_title:  removed 'photon cycle' 

message: I created a new article with the goal to develop a basic list that is logical, conceptually clear, and inclusive of all practicable approaches to building a machine to convert heat energy into mechanical energy. KYcrank 00:32, 6 November 2006 (UTC)
replies: text: appears to have been referring to material now found in the article Timeline of heat engine technology. Dolphin (t) 11:07, 20 September 2016 (UTC)
thread_title:  reference to new article: Heat engine classifications 

message: I've been interested in heat engines for some time, and I have never heard anyone make the argument (especially after just having pointed out that heat engines work on a heat differential, and extract power from that differential alone) that internal combustion engines are heat engines of any kind-- steam, gasoline, diesel...  These engines are, by no possible stretch of definitions I can think of, operating by differential in heat.  I was writing in here several examples of why it's past ridiculous to include many of these engine types as heat engines, but it's not even worth doing:  the statement itself is self-evidently ludicrous.  68.99.213.231 05:05, 4 January 2007 (UTC)
thread_title:  Agree with first two comments - This article is poor 

message: There is a new paper published in the "International Journal of Energy Research" (http://dx.doi.org/10.1002/er.1312) that details a new heat engine model that accurately reproduces the efficiencies of Otto, Brayton, and Stirling cycle engines. This new model should be covered under this topic. —The preceding unsigned comment was added by 69.244.46.21 (talk) 14:18, 7 March 2007 (UTC)
thread_title:  New heat engine model should be incorporated 

message: I came to this page hoping to find information about the efficiency of engines, but just a couple scattered references.  That would be a useful list, although I am sure it is hard to get consistent information.
Also, you might mention rocket engines in the article.  They may be the most efficient heat engines, up around 65%. DonPMitchell (talk) 17:54, 29 June 2008 (UTC)
replies: text: A rocket motor is not a heat engine. Mass crosses the system boundary. Globbet (talk) 20:01, 22 August 2008 (UTC)
replies: text: But under the steady flow assumption (see below) they can be treated as heat engines, and described using the Brayton cycle.  —Preceding unsigned comment added by 88.18.219.135 (talk) 10:35, 9 May 2009 (UTC)

text: An athermal heat engine is a contradiction in terms, and many heat engines exceed 33% efficiency; so I've deleted, what appears to me to be, OR.Teapeat (talk) 01:43, 22 April 2012 (UTC)
thread_title:  Efficiency 

message: The efficiency of traditional heat engines is a limit 1/3， 33.33%.Deng Yu，Deng Hai，热效率趋向100%的能量利用新途径I:从无序到有序，中国工程热物理学会，工程热力学与能源利用学术会议，1994Deng Yu，Deng Hai，邓宇，邓海，热效率趋向100%的能量利用新途径II:量子化内能的分解及有序化的演变，中国工程热物理学会，工程热力学与能源利用学术会议，1994 
Px=Py=Pz=P,
PV=(2/3)NEk =(1/3)mv2N 
when 3-Dimension
V2=Vx2+Vy2+Vz2
when 1-D in 3-Dimension
Vx2=3Vx2=3v2=V2
PxV=(1/3)mV2N=(1/3)mVx2N 
=(1/3)m3Vx2N
=mVx2N
=2EKN  
Px>P
Px=3P=3NRT/V  
ηs=A/Q=1 -(T2/T1)
=1 -(T2/Q1)S  
entropy S→0, 
so 
(T2/Q1)S→0,
ηs→1
0≤η<<1
Q=3PV
or
Q=U=3PV
η0=A/Q=PV/3PV
=1/3
A=3PV
ηs=A/Q=3PV/3PV
=1
:An athermal heat engine is a contradiction in terms, and many heat engines exceed 33% efficiency; so I've deleted, what appears to me to be, OR.Teapeat (talk) 01:43, 22 April 2012 (UTC)
thread_title: Athermal engines efficiency 100%

message: From the definitions of heat engines that I have seen, I don't believe that  internal combustion engines can be considered heat engines. This is because the input is chemical energy. This chemical energy is turned into heat internally and this heat is then turned into mechanical energy.  However, the input to the engine is chemical and not heat.  —Preceding unsigned comment added by PhillyPhysics (talk • contribs) 16:51, 26 July 2008 (UTC)
replies: text: Correct: an internal combustion engine is not a heat engine. Mass crosses the system boundary. Globbet (talk) 20:03, 22 August 2008 (UTC)
replies: text: Although they are in fact open systems, the internal combustion engines are modelled as heat engines, with their corresponding cycles (Otto, Diesel or Brayton). This is done using the steady flow assumption: as in every cycle enters the same amount of mixture as hot gas is expelled, it can be treated as if the same fluid were making the cycle continuously, with just the heat being discarded.--88.18.219.135 (talk) 10:34, 9 May 2009 (UTC)
thread_title:  Internal combustion engines can't be considered heat engines 

message: Do sterling cycles really require the fluid to be a gas? I ask because I've come across an obscure cycle that is described as being like a sterling cycle but using liquid rather than gas.
see http://www.douglas-self.com/MUSEUM/POWER/maloneliquid/maloneliquid.htm
thermodynamic cycles are described using cycles of thermodynamic processes so in much same way as a sterling is still a sterling if it runs on air or helium. So as long as the processes remain the same the choice of fluid shouldn't prevent the malone being considered a sterling.  — Preceding unsigned comment added by 82.47.140.47 (talk) 19:53, 28 August 2012 (UTC)
thread_title: Sterling cycle and Malone engine 

message: Added lede part and image to heat transfer, here. Prokaryotes (talk) 20:09, 6 April 2014 (UTC)
thread_title:  Heat transfer 

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thread_title:  External links modified 

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thread_title:  External links modified (January 2018) 

message: The tag Carnot efficiency redirects here, but since Carnot efficiency is so central to many applications other than engines, it would probably be useful to make this a separate article. Geoffrey.landis (talk) 14:44, 22 June 2020 (UTC)
replies: text: For 10 days in February 2007 the redirect was aimed at Exergy efficiency so that makes five! Dolphin (t) 22:21, 22 June 2020 (UTC)
thread_title:  Need an article on Carnot Efficiency