Talk:External combustion engine

message: I rewrote the introductory paragraph. It seems to me that we should also add a history section to this definition. 
The introductory paragraph needs to spell out the difference between the internal and external combustion engine. The main difference, as I see it, is that an internal combustion engine burns the working fluid, "Internal combustion". Hence, it must cycle the fuel oxidizer mix to have a new charge to burn. The external combustion engine doesn't burn the internal working fluid. The EC engine can burn the external working fluid but the heat can come from anywhere and thus is not a "combustion" engine at all. The IC engine's internal working fluid heats to a high temperature very rapidly, where the conduction of heat for an EC engine requires more time and surface area.
Both the internal and external engines work by the internal fluid expanding from heat. Both run a large variety of cycles. So the difference mainly appears to be whether the fluid inside is burnt or not. If it is an inert fluid it will not burn. It doesn't need to be inert to not burn.
The history should mention some of the first EC engines built and theorized, specifically the steam/vacuum and steam engines and those experiments of Guericke and Denis Papin, Savery, Newcomen, James Watt, and Ericsson. 
We could also mention the difference between an IC engine, EC engine and a theoretical engine.
One more thing: Many EC engines have been built and run with no heat exchanger, what so ever, they work by directly heating the outside of the engine mechanism/cylinder itself, and cooling it or the opposite side. A heat exchanger can be built into the mechanism or be a completely separate entity. Either way, a heat exchanger is an addition to the basic operating mechanism and should not be considered as a secondary function of that structure. 
If anyone has some improvement to the above viewpoint, or main article, please mention them so we can get the best description possible for the main page. 
Thanks Eric Norby 17:10, 27 March 2007 (UTC)
thread_title:  Scope of what this definition should contain 

message: In the article it mentions steam turbines, which I assume are widely regarded as external combustion engines, also often run on the heat provided by nuclear fission. Nuclear fission, then, must be a form of combustion - which it isn't. Can somebody explain this?
:Not qualified to discuss nuclear fission. However I think that as much as anything, your point is a semantic one and as such I have to say that I have long had problems with the whole term External Combustion - not just combustion. I think that the root of the problem is historical. In the early days of coal or wood firing, this was used to heat a boiler to provide steam pressure and that and/or condensation of it did the work.  This immediately brings up another problem I have with the term heat engine, IMO heat in itself never drove an engine. What drives the engine is the effect of heat on a gas or liquid; if the expanded fluid is constrained in a restricted space such as a boiler or a cylinder, pressure is created which can be made to act upon a moveable piston or rotor. If we restrict the term "heat engine" to disinguish its working principle from that of a "gravity engine" (water turbine) or an "eolian" engine (windmill), for instance, where the effect of heat is far less direct (sun on the atmosphere), then the situation is clearer. Consequently if you look on nuclear fission as a component of a heat engine or more specifically of a steam engine, its role is no different from that of, say, coal burning in a firebox, which answers your objection. It is when we develop the heat engine idea further that we run into problems. The term heat engine goes back to the very early days of industrial steam. Late 18th Century scientists were fascinated by heat: was it a substance (caloric, phlogiston) or a phenomenon (kinetic theory)? Today the latter theory has prevailed, but a man like Sadi Carnot who laid the foundations of thermodynamics saw heat in terms of the substance, "caloric". (By the way, the Carnot heat engine article is much improved lately). In the mid-19th Century the internal combustion engine comes along with the invention of gas (coal-gas, not gasoline) engines and what is the process there? The same as before only faster: compression or an electric spark or a glowing coil ignites a volatile gas or air/liquid mixture creating a rapid pressure increase which moves the piston. As this all takes place inside the power cylinder and eliminates the requirement for a separate boiler, the process is called internal combustion. The point is that before the invention of internal combustion, there was no need for an opposite term and one wonders when external combustion was coined. I suspect it was relatively recently and what seems likely is that it was coined simply as the opposite of internal combustion. Today when most heat engines you see working every day are of the internal combustion type, that is the term of reference. Being a defensor of of steam technology, I can tell you that the level of ignorance regarding steam, even on the part of many engineers is unbelievable. One of Ted Pritchard's  quips is something like "we never show the cylinders what we are burning", which aptly sums up the situation. External combustion may be semanically correct and just about applicable to a Stirling cycle engine, but regarding steam engines it represents absolutedly nothing and just adds to the general confusion. I have suggested that we should speak rather of separate combustion. It is interesting in this context to quote the opening sentence in the Wikipedia article: "An external combustion engine is a heat engine which burns fuel to heat a separate working fluid". The difference is that I visualise it in terms of the heat source being separate from power delivery. Of course I am on a personal hobby-horse here (POV) and as such my suggestion has no place an encyclopedia - or Wikipedia. No problem with that, but it does mean that when writing for Wikipedia or any encyclopedia we sometimes have to compromise and accept things we don't completely agree with or cope with inadequate terminology that nevertheless allows clarification of some essential point. I haven't answered your question but perhaps I have shown that it is part of a wider, fundamental one that nobody seems willing or able to tackle - the weight of history! The proof is that nobody has taken me up here on this yet, even though my point of view is very controversial. --John of Paris 11:58, 25 November 2006 (UTC)
thread_title:  Nuclear fission; non-related? 

message: Can some one also explain the limitations of EC engines? The commercial viability of EC engines..
202.136.14.9 (talk) 05:25, 30 January 2008 (UTC)
replies: text: If you refer to the discussions above, you will see that there has some disagreement on the definition of EC, which in my opinion should exclude steam technology. However when we talk about EC, it turns out that we are mostly discussing steam, so in trying to answer your questions, I can only refer to steam technology, and there, outside of large-scale electricity generation, we can say that the present commercial viability of steam is precisely zero. This does not mean that it has no future in applications other than the above, such as small-scale electricity generation, transport etc -all uses where IC at present has the monopoly. Quite the contrary: anyone interested will be bewildered by the number of serious projects under way and it seems that when one of these projects runs out of money and falls, another pops up and replaces it. Steam technology just refuses to go away. To my mind, the most serious limitation is that it demands a radically different approach from the now-predominant IC technology and mean retraining of those involved in it. This means that there are now few people who really master it. So any involvement in it would certainly entail an element of risk, probably worthwhile, but that's my personal judgement that all should make for themselves. Your own seeming bewilderment suggests to me that this External combustion article explains nothing, which has always been my problem with it.--John of Paris (talk) 17:28, 30 January 2008 (UTC)
thread_title: Request for information

message: Me again! Turning up again like a bad penny! Been going through the history of this article this evening. One thing that strikes me is that since its creation in 2003 no reliable sources have been cited, especially those that might give some credibility for the strange term External combustion itself. I make this comment not only because I disagree with the validity of the term (which I do), but because am curious to know its origin. My own first encounter with it was back in 2002 in the writings of Ted Pritchard, the Australian steam car developer on his fascinating now-dead site Inventadata,. Unfortunately these papers are no longer accessible on the web, although I have kept personal downloads. I think I am right in saying that as far as Ted was concerned, "external combustion engine" was only another way of saying "steam engine" avoiding the associated "out-of-date" stigma. That's OK by me as far as it goes, except that a rose by any other name... What I am less comfortable with is finding the Stirling motor here in the same basket, the reason being simply that unless someone can prove me wrong, I cannot imagine how one can store energy in a Stirling engine the way steam can be stored under pressure in a well insulated boiler for subsequent use - notably in the case of a fireless locomotive. For me a steam engine as a prime mover, with all its faults and advantages is a unique case - it cannot be compared with any other. — So there's the challenge - cite your sources please, I'm dying to know...--John of Paris (talk) 22:12, 3 March 2008 (UTC)
replies: text: While not a reliable source, the term goes back at least a decade before that, without much effort I found a reference to it in 1985 on google groups, and in 1989 referring to stirling engines (shrugs).- (User) WolfKeeper (Talk) 23:37, 3 March 2008 (UTC)

text: Clearly this is not a new term, and it has been in books since 1961 or before.- (User) WolfKeeper (Talk) 15:34, 4 March 2008 (UTC)

text: Uh huh. You don't need to pay anything. This is not in any way a new term. I found a book listed first published in 1905 using it to refer to Stirling engines, and here's google's excerpt: , and there's plenty more referring to steam engines.- (User) WolfKeeper (Talk) 20:48, 4 March 2008 (UTC)

text: To be strictly accurate, that excerpt is from 'v.111 1960 Feb-Jul'; so the term goes back at least to 1960. The bottom line is, this isn't in any way a new term, it's trivial to find references to it in old publications.- (User) WolfKeeper (Talk) 15:05, 5 March 2008 (UTC)
thread_title: Citations? - a challenge to the editors of this article

message: Don't know about Brayton, but I'd still like to know what a 'Papin cycle" is and where it has been applied, --John of Paris (talk) 23:55, 11 March 2008 (UTC)
thread_title: Papin cycle

message: Can anyone give an example of a liquid-only external combustion engine? Biscuittin (talk) 18:27, 12 February 2012 (UTC)
replies: text: Fluidynes. Very obscure, but they were considered in the 1970s as no-moving-parts pumps. Usually though, the limited volume change compared to either the phase change, or the volume change of a heated gas, makes a liquid-only engine impractical. By relying instead on the weight change from gravity on a fluid of changing density (and using tall heated columns with a small working volume between them), a purely liquid engine can be made. Andy Dingley (talk) 00:15, 13 February 2012 (UTC)
thread_title:  Liquid-only external combustion engine