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Comments 51 to 66 out of 66:

51. scaddenp at 10:18 AM on 30 October, 2012
    "Exactly". Something that takes a complete redesign of the car is not a stopgap measure - it would take 25years to replace vehicle fleet with new technology. We would be better off doing that transition to electric rather than a pure O2 fossil fuel burner. For a pure O2 burner to get more kms per litre of fossil fuel, it needs to be a lot better at converting chemical energy to kinetic and as a result must exhaust much less heat. At first glance, it is hard to see how pure O2 makes that difference. You have either carry heavy O2 tank on car as well as fuel, or carry an O2-stripping apparatus in the car as well. Pure o2 should result in more power so perhaps a smaller engine but an internal combustion engine is going to have major fun with the temperature. I'm skeptical - electric seems better to me - but I'm open to be convinced by actual designs.
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52. Bernard J. at 12:20 PM on 30 October, 2012

    You go to a gas station to fill up on hydrocarbon fuel which powers an engine designed to eficiently burn the hydrocarbon fuel with pure oxygen. The hydrogen combines with oxygen to produce heat and H2O. The carbon combines with oxygen to produce heat and CO2. The temperatures attainable are higher than using air, which contains 79% Nitrogen. The efficiency of a heat to work engine is proportional to the difference between the highest and lowest cycle temperatures (Carnot). The products are work, CO2 and water. The CO2 can be temporarily captued in a recyclable media, which is recycled at the gas station while you fill up. Zero emissions, much better gas mileage, higher efficiency, unbelievable power.

    I'd like to see the energy budget that accounts for: 1) the costs of purifying, storing and delivering the O₂, 2) the costs of collecting, storing and safely and permanently disposing of the CO₂ and, as others have pointed out, 3) for the vehicle retooling that would be necessary. How do these thermodynamically-unavoidable costs compare with the increased combustion efficiently returned from using pure oxygen?
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53. vrooomie at 23:10 PM on 30 October, 2012
    Bernard J, let me take a shot at answering your questions... Re: "pure" O2 in an engine, I'll stand by my statement: There is *NO* internal combustion engine that will run on pure O2, nor benefit appreciably by the use of O2. Yes, adding pure O2 will indeed make combustion hotter..and decrease fuel mileage, due to the fact of the engine needing more fuel to maintain stochiometry. I happened to have done this professionally, i.e, built, run, and test automotive engines; in 1980, a local physicist sought my dad an I out to run these EXACT tests, that is, running an auxiliary O2 enrichment system on standard automobiles and trucks. One of the test "mules" was a 1981 Chevy Suburban, which I ran ~2000 miles to establich baseline fuel usage data. I then replaced all the lubricants with high-tech (for then) synthetic lubricanbts, then ran *another* 2000 miles to determine their efficacy. Standard, as delivered: 10 mpg, city; 13 mpg highway. Standard, with modified lubricants: almost identical numbers, with ~ less than 1% improvement. I then modified the engine to attain higher volumentric and thermodynamic efficiency (different cam timing, improved induction system, precision balancing, better fuel and timing mapping. Modded engine, standard lubricants: 11 mpg, city, 14 mpg, highway. Modded engine, synthlubes: a repeated ~1% improvement. We then developed the O2 injection system and ran it for ~5000 miles...the *astounding* results? 11.6 mpg, city, 14.1 mpg, highway. In a word, it was essentially useless to inject pure O2 into the engine. On top of that the exhaust emissions were not substantially decreased (given the coarse and low standards of the time) and I can almost assuredly say that any improvements today would be subsumed by the high cost of O2 refinement/storage and distribution. I repeat: O2 injection does NOT make an appreciable difference and is costly to do. Modern engines in cars are just about as efficient as a *reciprocating* engine can be made.I also We cannot do a lot better, using IC engines: what we can do is to continue using modern, lower-weight composite structures (ala F1/CART/IndyCar technology), increasing CAFE standards, and *conserving,* i. e. move ~away~ from so much individual car use. Sorry car guys, but the day of the internal combustion-powered car is, thankfully, numbered. I must say that this was a painful admission for me, who lived, ate, and breathed the car game all my life, and will, so long as I can afford the fuel, continue to play with my one toy car. I will, however, ASAP, be buying a hi-mileage European turbodiesel hybrid, as soon as CARB pulls its regulatory thumb out of its administrative ....behind.
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54. Bernard J. at 00:25 AM on 31 October, 2012
    Vrooomie. Thanks for a very intriguing response. Given the results that you report it follows that the costs of purifying, storing and delivering the O2, and the costs of collecting, storing and safely and permanently disposing of the CO2 would all have to be effectively zero to warrant even the few percent benefit that you observed with using oxygen enrichment. And in the real world the laws of thermodynamics will not permit those (very large) costs to be avoided. It would seem that sincam shot all of his tappets.
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55. vrooomie at 01:46 AM on 31 October, 2012
    Bernard J, now, when I see the exhaust pipes of IC vehicles, irrespective of how clean they've gotten, all I can see is an open sewer pipe: it offends me in many ways. We (finally, eventually) learned to stop puking our effluent into the Cuyahoga River (and many other rivers) and it's now WAY past time we quit dumping into the commons of the atmosphere. It's immoral.
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56. sincam at 07:48 AM on 1 November, 2012
    Re: "pure" O2 in an engine, I'll stand by my statement: There is *NO* internal combustion engine that will run on pure O2, nor benefit appreciably by the use of O2. I agree. It would take a new design, not a jury rig. Check patents 8176884, 7543577, and others. The original post pointed out POSIBILITIES because of a NEW efficient, economical way to produce pure O2 and allow carbon capture. All present methods to produce O2 are about 14% efficient compared to the theoretical energy it should require (exergy). This means it takes about 8 times the energy and lots of equipment. Coal power plants, fuel cells, industrial furnaces, and cars and everything else, are designed to operate in our 21% O2 atmosphere. What would they look like on a planet that had a 100% O2 atmosphere?
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57. Dikran Marsupial at 07:53 AM on 1 November, 2012
    sincam wrote: "What would they look like on a planet that had a 100% O2 atmosphere?" Non-existent I should think. In a 100% O2 atmosphere more or less everything carbon-based would be so flamable that we wouldn't have evolved enough to make them.
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58. scaddenp at 09:59 AM on 1 November, 2012
    Dikran - the real question is what would generator look like if they had 100% oxygen intake. sincam - it is not clear at all to me how a boiler running on 100% O2 would be significantly more efficient. It's not like a coal plant has lot a lot of energy in CO emissions or that they could get the steam much hotter.
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59. vrooomie at 00:16 AM on 2 November, 2012
    As I demonstrated, increasing O2 partial pressure in a combustion engine results in very little improvement in EROI terms. And Dikran's correct: A 100% O2 atmosphere is lethal: ref: Apollo 1. Also, let me me state this a little more forcefully: NO combustion engine, powerplant, or anything else that operated by burning a/some fuel would operate AT ALL with pure O2: it is non-combustible, by itself. There ARE no magical engine designs that will work on O2, irrespective of how much money and fanciful hopes are thrown at them.
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60. sincam at 10:31 AM on 10 November, 2012
    Lets see, you demonstrated that at some unknown partial pressure (% O2 enrichment), the trial you were involved in with a conventional engine, did not offer any advantages. No supprise. Check the fuel and, guess what, is used in rocket engines. They work pretty well.
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    Moderator Response:

    [DB] Examining the Space Shuttle engines:

    solid propellant fuel - atomized aluminum (16 percent) oxidizers - ammonium perchlorate (70 percent) catalyst - iron oxide powder (0.2 percent) binder - polybutadiene acrylic acid acrylonite (12 percent) curing agent - epoxy resin (2 percent)

    And the liquid-fueled engines of the Orbiter:

    The engines burn liquid hydrogen and liquid oxygen, which are stored in the external fuel tank (ET), at a ratio of 6:1. Source

    Guess what? Unless you have something substantive to say on that topic (read: actual published references from a reputable source that contextually support your position), it is no longer a welcome part of this discussion. No surprise.

61. Tom Curtis at 11:36 AM on 10 November, 2012
    sincam @60, the most efficient combustion occurs when there is two oxygen atoms for every one carbon atom, and an additional oxygen atom for every two hydrogen atoms in the fuel. At that ratio, complete oxidization (combustion) of the carbon and hydrogen can be achieved resulting in the maximum energy release. Including more oxygen beyond that point does not result in the release of more energy for a given amount of fuel. It merely makes combustion easier resulting in more potential combustion prior to the fuel entering the combustion chamber. For normal power requirements, the air contains more than sufficient oxygen to provide a lean mixture (ie, one with excess oxygen) and hence no advantage is obtained by introducing more oxygen. The introduction of more oxygen, even pure oxygen is advantageous where you simultaneously introduce more fuel and produce more energy per second as a result. Note, however, that you produce more energy per second. Not more energy. You obtain exactly the same amount of energy per kilogram of fuel used as though you had not introduced oxygen. So, there is an advantage in using pure oxygen for rocket engines, where raw power is desirable. For normal transport uses, however, current fuel usage and power output is more than adequate so introducing oxygen provides no advantage.
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62. Lanfear at 07:07 AM on 11 November, 2012
    sincam@60 and Tom Curtis@61 Sorry if I'm being thick here, but I thought the reason why (chemical space-)rockets are carrying oxygen with them is that they go to space, where notoriously there is no air/oxygen/anything (almost). Otherwise I think that comparing internal combustion engines to rockets is apples to oranges, since the rockets do not have to deal with the created heat in the same way. FWIW I think that even supercharged (or turbo) diesels do produce some soot, which would imply that not all the fuel is converted into CO2 and H2O. I am however skeptical whether this behaviour could be inproved by enriching the intake air. Oh, and I don't recommend mixing 100% O2 with anything carbon (including the lubricant of the piston) especially with alternating pressure. You will get an uncontrolled detonation. In fact there is a rule in the diver world where the first and second stage has to be 'oxygen clean' when using mixes stronger than EANx40.
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63. Tom Curtis at 11:41 AM on 11 November, 2012
    Lanfear @62, space rockets certainly carry oxidizing agents in part because it is hard to find oxygen in a vacuum. However, rocket cars also carry oxidizing agents, and that is certainly not the issue for them. The need for very rapid combustion to produce maximum power, however, is. With regard to diesel engines and soot, whether or not they produce soot will depend on a number of factors including their cycle (two stroke engines will always have uncombusted fuel), and age (worn engines will admit sump oil which burns poorly and produces soot). As it happens, I have seen diesel engines in which I could not detect any soot by eye (or nose), but that may not be the relevant test. Never-the-less, I think you need to support your claim a bit better. With regard to pure O2, you are quite correct. Indeed, ordinary grease can spontaneously explode in a pure oxygen atmosphere (one of the safety hazards boilermakers need to be warned of).
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64. Lanfear at 02:51 AM on 13 November, 2012
    Tom Curtis@63 "Never-the-less, I think you need to support your claim a bit better." No strong evidence, only my own perception of that the actual problem that the engine-engineer have been trying to solve is (as you also note) the even distribution of the fuel with the intake air. Incidently (if the linked Wikipage is accurate), the O2-level of the diesel exhaust would indicate that the issue is not asmuch O2, rather some other factor. OTOH there is not any O2 in the gasoline(petrol) exhaust, but a sizeable amount of CO which could be the result of too rich mixture resulting in O2 'starvation' and incomplete oxifidation of the carbon, or reversely, not enough O2. Hmm... if only Vroomie had done some exhaust analysis on his Suburban in the different configurations, then his example would not be up for speculation. Regarding the rockets, I still am of the view that they are apples, since sincam's original claim included a possible design with high efficiency and zero emission (carbonwise I presume). Hence the rocket (in any form my limited imagination can procure) is out of the question since it does in effect rely on having the combustion gases immediately expelled to the environment as a mean of propulsion. His reference to rockets is thus an irrelevant distraction.
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65. mjp at 12:56 PM on 6 December, 2012
    guys the update version of the escalator is great can you provide non-animated versions of the skeptic and realist gifs for use on forums that don't allow animated posts?
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66. dana1981 at 17:12 PM on 6 December, 2012
    mjp @65, I'll include the last individual frames in the next Escalator update, which should come in the next couple of weeks.
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