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Where is the Negative paragraph. This EGR system causes SLUDGE in cars. This is a huge cost to vehicle owners. EGR should be reconsidered. The EPA should not have control of vehicle manufacturing. Who pushed for EGR? Who invented it? No one knows. -- 2605:6000:1A0D:1C0:0:94F:F47E:FDD1 ( talk) 07:17, 8 August 2018 (UTC)
The neutrality of the section is being disputed due to environmental claims lacking citations as well as on going reverts , in order to prevent an edit war this section of the talk page has be created to improve the article. Wikipedia requires reliable resource to be valid. Kateweb ( talk) 14:30, 29 July 2010 (UTC) Wikipedia:Identifying reliable sources Kateweb ( talk) 14:48, 29 July 2010 (UTC)
That's a good start you made. I've put your addition into encyclopædic format—paragraphs rather than a bullet-point list—and consolidated your three referrals to the one reference. Also I've changed the arcane term "end gas" to the accessible one "exhaust". — Scheinwerfermann T· C 02:49, 6 February 2011 (UTC)
With the amount of editing that goes into Jessica Simpson's Wikipedia page and the flurry of "citation needed" tags that abound on most pages this 'article' is dismal, almost everything on the page has been written by few people who do not understand modern combustion kinetics and the rationale for emissions equipment! The article needs to be rewritten from a NPV by someone who understands how automotive emissions equipment works. . . —Preceding unsigned comment added by 72.33.133.175 ( talk) 00:03, 27 July 2010 (UTC)
Agreed. This statement alone makes no sense: 'This means the heat of combustion is less, and the combustion generates the same pressure against the piston at a lower temperature.' If exhaust gases are displacing either air or fuel, then at least the second part of that statement cannot be true since it cannot generate the same pressure. I don't think whomever wrote this article really knows what he/she is talking about. —Preceding unsigned comment added by Jatkins679 ( talk • contribs) 21:58, 21 November 2010 (UTC)
The statement "Reduced heat rejection. Lowered peak combustion temperatures not only reduces NOx formation, it also reduces the loss of thermal energy to combustion chamber surfaces, leaving more available for conversion to mechanical work during the expansion stroke" is partially correct. The "Heat reduction" part is correct, but it does not lead to "leaving more available for conversion to mechanical work during the expansion stroke". If you have less energy (heat) and consequent less temperature on the combustion chamber, it will lead to less heat energy being converted to "mechanical" energy. The highest the temperature on the combustion chamber (through normal combustion, I am not talkin about detonation), the highest will be the engine efficiency... This is thermodynamics 101. — Preceding unsigned comment added by Alecesa ( talk • contribs) 04:09, 17 December 2010 (UTC)
Your understanding of Thermodynamics 101 is flawed. The temperature at which heat addition occurs (for the Otto cycle, this is the peak combustion temperature) is not the only factor affecting efficiency; The heat rejection temperature (exhaust temp) also matters. In the absence of heat loss to the combustion chamber surfaces, the ratio between these two temperatures is determined entirely by the compression ratio (see Otto cycle, Equation #6). In the absence of any heat loss to the combustion chamber surfaces, lowering the peak temperature at TDC does not reduce efficiency; this is because lowering the peak temperature also reduces the exhaust temperature When heat loss to the combustion chamber surfaces is factored in, lowering the peak combustion chamber actually increases efficiency (by reducing that heat loss). This is one of the major reasons why diesel engines have great part-load efficiency (the excess air acts as a diluent that helps keep peak temperatures down, reducing heat loss to the walls). Joe Frickin Friday ( talk) 20:57, 25 February 2016 (UTC)
the part where it says almost all modern engines need EGR, what the heck i don't think so. — Preceding unsigned comment added by 64.135.212.67 ( talk) 00:54, 8 January 2014 (UTC)
"environmental impact of EGR outweighs the NOx emission" in the last paragraph does not make sense. NOx emission is an environmental impact. —Preceding unsigned comment added by 69.224.45.140 ( talk) 16:52, 15 March 2009 (UTC)
NOx is not a greenhouse gas. Nitrous oxide (N2O) is a greenhouse gas. NOx is a mixture of NO and NO2.
Is it really 'polution' or is this a mis-spelt 'pollution'? -- SGBailey 23:36 Dec 16, 2002 (UTC)
Changed the EGR composition to include the most significant component: nitrogen! 129.55.200.20 ( talk) 15:36, 26 August 2016 (UTC)
In an SI engine, the inert EGR is *added* to an existing mixture. The addition of inert exhaust gas, with its high specific heat, results in a rather large reduction in peak temperature (and corresponding reduction in NOx production)
In a CI engine, the inert EGR *substitutes* for a portion of the atmospheric air entering the cylinder. The *substitution* (rather than addition) of exhaust gas, with its high specific heat, results in a smaller reduction in peak temperature (and therefore a smaller reduction in NOx) than is observed in SI engines.
short version of EGR effects:
SI - same energy, larger total in-cylinder mass, larger specific heat ---> much lower temperature/NOx
CI - same energy, SAME total in-cylinder mass, larger specific heat ---> modest reduction in temperature/NOx
Joe Frickin Friday 15:47, 21 March 2006 (UTC)
*Putting end gas back into the engine cylinder in place of fresh filtered air adds wear-inducing contaminants and increases engine oil acidity, both of which reduce engine longevity.
*EGR reduces engine power.
*EGR badly affects fuel economy.
This is a Domino effect. When longevity is effected, efficiency goes with it. When efficiency goes down, so does power and fuel economy. The acidity in the crankcase of EGR diesel engines is going to be worse than that of gasoline engines. (There is a elementary reason why this is, but I can't source it, so it doesn't matter on wiki.)-- Dana60Cummins ( talk) 16:46, 29 July 2010 (UTC)
It's my understanding that the addition of exhaust gas also increases the mass of gas in the cylinder at part throttle during the compression/power strokes. This increases the compression ratio at part throttle. This increased pressure improves the thermodynamic efficiency. (Warning, I'm not a physicist, just a motorsickle sumbitch). I think this effect in not trivial.
Also, the heat rejection bit could be elaborated. Because the peak temperature of the combustion gasses is lower, the entire engine runs cooler. Usually, the manufacturer/designer uses an engine thermostat that's a little higher temperature to ensure the engine stays warm enough to keep the fuel vaporized, keep water vaporized, and further improves heat rejection by reducing the temperature differential between the exhaust gas and the cylinder head.
Finally, it might be helpful to dispel the idea that EGR is an attempt to 'reburn' unburnt exhaust gasses. This is the most common misperception about EGR and the main reason that uninformed guys with tools remove EGR systems.
Pcmenten 22:08, 29 December 2006 (UTC) Paul Menten
EGR can definitely hurt efficiency. I performed very careful measurements with a 1995 Toyota Corolla (1.8L non-Calif. model) on a weekly commute, mostly highway, air conditioner off. After EGR was disconnected, highway mileage went from 34-35 mpg to a consistent 38-40mpg. This makes sense, since EGR reduces combustion temperatures and thus Carnot efficiency. It is interesting to note that the 1.6L version of this car is not equipped with EGR, except in California. This leads me to think that its effect is largely detrimental, and it's there mainly as an emissions band-aid. This is a vacuum-modulated EGR valve with an ECU-controlled VSV acting as an on/off switch.
Also, the Heywood book is largely regarded as outmoded as far as its empirical data in it is concerned. The section on EGR seems to be based exclusively on simulations, which may not be terribly accurate. Unilaterally stating that EGR helps efficiency is obviously incorrect. 64.251.148.91 07:35, 31 July 2007 (UTC)
in a diesel engine using an egr system, is the aim to obtain an overall air / fuel ratio of 14.7:1 (the stochimetric ratio) by using the exhaust to subsitute the excess air? 84.66.42.255 22:48, 31 March 2007 (UTC)
in the 80's, it was smog reduction! So instead of running lean and efficient, they run EGR, run rich and burn up more fuel! Less nitrogen oxides tho, so less smog!
67.189.106.110 (
talk)
06:02, 11 March 2012 (UTC)
The Technology Barnstar | ||
I can't see a single editor who wrote most of this article so I'm awarding the entire EGR editing team a barnstar. The information on this page got my wife's Mazda running this morning and won me major skillz points! I owe you one! SteveBaker ( talk) 15:22, 12 December 2007 (UTC) |
at the time of this talk comment thier are no online references for this article , only 2 books. —Preceding Kateweb ( talk • contribs) 02:09, 29 July 2010 (UTC) as an update I an waterppk are working to improve citations y adding ones that are accessible, if you find any resources that could apply and you don't know what part of the article to apply rhem to place them here and one of us will look at them . Kateweb ( talk) 02:37, 29 July 2010 (UTC)
This section, even in its present bare-bones form, is idealogically lopsided. Dana60Cummins, it is very apparent from your contributions to this article, this talk page, and your own talk page that you don't like EGR on diesel engines. That in itself is a problem; theoretically it should not be possible to determine a good editor's personal preferences and opinions from the contributions s/he makes. At least you've supported your assertion with a couple of refs, which is good, but I'm afraid the notion just doesn't hold water that diesel EGR is a nefarious, thoughtless mistake forced on a sheeplike industry by ignorant morons at the EPA. In the very large and well-documented context of the overall vehicular-emissions cleanup effort over the last fifty years, that idea just isn't very sturdy. EGR gives benefits on diesel engines or it wouldn't be there. Whether those benefits are as large as stated and/or are equal to whatever drawbacks—those are debatable points, and as long as there's reliable support for assertions one way or the other, there's nothing wrong with including them in this article. But this "diesel EGR is bad" stuff just doesn't cut it on its own. — Scheinwerfermann T· C 02:52, 16 May 2011 (UTC)
″Exhaust gas—largely carbon dioxide and water vapor″ - well that might be true if the combustion was taking place in an oxygen enriched atmosphere. With combustion in air (or in air with recirculated exhaust gases) the exhaust gases will be predominantly nitrogen - I think between 73.8% and 79% depending on how much oxygen was consumed. — Preceding unsigned comment added by 2.125.187.47 ( talk) 18:27, 27 September 2015 (UTC)
Alexander Noé ( talk) 19:23, 17 October 2023 (UTC)
Although it wasn't designed as such, Exhaust pulse pressure charging is probably a form of Exhaust gas recirculation. Biscuittin ( talk) 22:01, 27 April 2015 (UTC)
Does anyone know the peak temperature that is generated with, and without EGR? That is NOx generating temperture? There is discussion in RP-1 about NOx generation from rockets. Gah4 ( talk) 18:02, 6 August 2020 (UTC)
This page is not a forum for general discussion about Exhaust gas recirculation. Any such comments may be removed or refactored. Please limit discussion to improvement of this article. You may wish to ask factual questions about Exhaust gas recirculation at the Reference desk. |
This article is rated C-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||||||||||||||||||||
|
Where is the Negative paragraph. This EGR system causes SLUDGE in cars. This is a huge cost to vehicle owners. EGR should be reconsidered. The EPA should not have control of vehicle manufacturing. Who pushed for EGR? Who invented it? No one knows. -- 2605:6000:1A0D:1C0:0:94F:F47E:FDD1 ( talk) 07:17, 8 August 2018 (UTC)
The neutrality of the section is being disputed due to environmental claims lacking citations as well as on going reverts , in order to prevent an edit war this section of the talk page has be created to improve the article. Wikipedia requires reliable resource to be valid. Kateweb ( talk) 14:30, 29 July 2010 (UTC) Wikipedia:Identifying reliable sources Kateweb ( talk) 14:48, 29 July 2010 (UTC)
That's a good start you made. I've put your addition into encyclopædic format—paragraphs rather than a bullet-point list—and consolidated your three referrals to the one reference. Also I've changed the arcane term "end gas" to the accessible one "exhaust". — Scheinwerfermann T· C 02:49, 6 February 2011 (UTC)
With the amount of editing that goes into Jessica Simpson's Wikipedia page and the flurry of "citation needed" tags that abound on most pages this 'article' is dismal, almost everything on the page has been written by few people who do not understand modern combustion kinetics and the rationale for emissions equipment! The article needs to be rewritten from a NPV by someone who understands how automotive emissions equipment works. . . —Preceding unsigned comment added by 72.33.133.175 ( talk) 00:03, 27 July 2010 (UTC)
Agreed. This statement alone makes no sense: 'This means the heat of combustion is less, and the combustion generates the same pressure against the piston at a lower temperature.' If exhaust gases are displacing either air or fuel, then at least the second part of that statement cannot be true since it cannot generate the same pressure. I don't think whomever wrote this article really knows what he/she is talking about. —Preceding unsigned comment added by Jatkins679 ( talk • contribs) 21:58, 21 November 2010 (UTC)
The statement "Reduced heat rejection. Lowered peak combustion temperatures not only reduces NOx formation, it also reduces the loss of thermal energy to combustion chamber surfaces, leaving more available for conversion to mechanical work during the expansion stroke" is partially correct. The "Heat reduction" part is correct, but it does not lead to "leaving more available for conversion to mechanical work during the expansion stroke". If you have less energy (heat) and consequent less temperature on the combustion chamber, it will lead to less heat energy being converted to "mechanical" energy. The highest the temperature on the combustion chamber (through normal combustion, I am not talkin about detonation), the highest will be the engine efficiency... This is thermodynamics 101. — Preceding unsigned comment added by Alecesa ( talk • contribs) 04:09, 17 December 2010 (UTC)
Your understanding of Thermodynamics 101 is flawed. The temperature at which heat addition occurs (for the Otto cycle, this is the peak combustion temperature) is not the only factor affecting efficiency; The heat rejection temperature (exhaust temp) also matters. In the absence of heat loss to the combustion chamber surfaces, the ratio between these two temperatures is determined entirely by the compression ratio (see Otto cycle, Equation #6). In the absence of any heat loss to the combustion chamber surfaces, lowering the peak temperature at TDC does not reduce efficiency; this is because lowering the peak temperature also reduces the exhaust temperature When heat loss to the combustion chamber surfaces is factored in, lowering the peak combustion chamber actually increases efficiency (by reducing that heat loss). This is one of the major reasons why diesel engines have great part-load efficiency (the excess air acts as a diluent that helps keep peak temperatures down, reducing heat loss to the walls). Joe Frickin Friday ( talk) 20:57, 25 February 2016 (UTC)
the part where it says almost all modern engines need EGR, what the heck i don't think so. — Preceding unsigned comment added by 64.135.212.67 ( talk) 00:54, 8 January 2014 (UTC)
"environmental impact of EGR outweighs the NOx emission" in the last paragraph does not make sense. NOx emission is an environmental impact. —Preceding unsigned comment added by 69.224.45.140 ( talk) 16:52, 15 March 2009 (UTC)
NOx is not a greenhouse gas. Nitrous oxide (N2O) is a greenhouse gas. NOx is a mixture of NO and NO2.
Is it really 'polution' or is this a mis-spelt 'pollution'? -- SGBailey 23:36 Dec 16, 2002 (UTC)
Changed the EGR composition to include the most significant component: nitrogen! 129.55.200.20 ( talk) 15:36, 26 August 2016 (UTC)
In an SI engine, the inert EGR is *added* to an existing mixture. The addition of inert exhaust gas, with its high specific heat, results in a rather large reduction in peak temperature (and corresponding reduction in NOx production)
In a CI engine, the inert EGR *substitutes* for a portion of the atmospheric air entering the cylinder. The *substitution* (rather than addition) of exhaust gas, with its high specific heat, results in a smaller reduction in peak temperature (and therefore a smaller reduction in NOx) than is observed in SI engines.
short version of EGR effects:
SI - same energy, larger total in-cylinder mass, larger specific heat ---> much lower temperature/NOx
CI - same energy, SAME total in-cylinder mass, larger specific heat ---> modest reduction in temperature/NOx
Joe Frickin Friday 15:47, 21 March 2006 (UTC)
*Putting end gas back into the engine cylinder in place of fresh filtered air adds wear-inducing contaminants and increases engine oil acidity, both of which reduce engine longevity.
*EGR reduces engine power.
*EGR badly affects fuel economy.
This is a Domino effect. When longevity is effected, efficiency goes with it. When efficiency goes down, so does power and fuel economy. The acidity in the crankcase of EGR diesel engines is going to be worse than that of gasoline engines. (There is a elementary reason why this is, but I can't source it, so it doesn't matter on wiki.)-- Dana60Cummins ( talk) 16:46, 29 July 2010 (UTC)
It's my understanding that the addition of exhaust gas also increases the mass of gas in the cylinder at part throttle during the compression/power strokes. This increases the compression ratio at part throttle. This increased pressure improves the thermodynamic efficiency. (Warning, I'm not a physicist, just a motorsickle sumbitch). I think this effect in not trivial.
Also, the heat rejection bit could be elaborated. Because the peak temperature of the combustion gasses is lower, the entire engine runs cooler. Usually, the manufacturer/designer uses an engine thermostat that's a little higher temperature to ensure the engine stays warm enough to keep the fuel vaporized, keep water vaporized, and further improves heat rejection by reducing the temperature differential between the exhaust gas and the cylinder head.
Finally, it might be helpful to dispel the idea that EGR is an attempt to 'reburn' unburnt exhaust gasses. This is the most common misperception about EGR and the main reason that uninformed guys with tools remove EGR systems.
Pcmenten 22:08, 29 December 2006 (UTC) Paul Menten
EGR can definitely hurt efficiency. I performed very careful measurements with a 1995 Toyota Corolla (1.8L non-Calif. model) on a weekly commute, mostly highway, air conditioner off. After EGR was disconnected, highway mileage went from 34-35 mpg to a consistent 38-40mpg. This makes sense, since EGR reduces combustion temperatures and thus Carnot efficiency. It is interesting to note that the 1.6L version of this car is not equipped with EGR, except in California. This leads me to think that its effect is largely detrimental, and it's there mainly as an emissions band-aid. This is a vacuum-modulated EGR valve with an ECU-controlled VSV acting as an on/off switch.
Also, the Heywood book is largely regarded as outmoded as far as its empirical data in it is concerned. The section on EGR seems to be based exclusively on simulations, which may not be terribly accurate. Unilaterally stating that EGR helps efficiency is obviously incorrect. 64.251.148.91 07:35, 31 July 2007 (UTC)
in a diesel engine using an egr system, is the aim to obtain an overall air / fuel ratio of 14.7:1 (the stochimetric ratio) by using the exhaust to subsitute the excess air? 84.66.42.255 22:48, 31 March 2007 (UTC)
in the 80's, it was smog reduction! So instead of running lean and efficient, they run EGR, run rich and burn up more fuel! Less nitrogen oxides tho, so less smog!
67.189.106.110 (
talk)
06:02, 11 March 2012 (UTC)
The Technology Barnstar | ||
I can't see a single editor who wrote most of this article so I'm awarding the entire EGR editing team a barnstar. The information on this page got my wife's Mazda running this morning and won me major skillz points! I owe you one! SteveBaker ( talk) 15:22, 12 December 2007 (UTC) |
at the time of this talk comment thier are no online references for this article , only 2 books. —Preceding Kateweb ( talk • contribs) 02:09, 29 July 2010 (UTC) as an update I an waterppk are working to improve citations y adding ones that are accessible, if you find any resources that could apply and you don't know what part of the article to apply rhem to place them here and one of us will look at them . Kateweb ( talk) 02:37, 29 July 2010 (UTC)
This section, even in its present bare-bones form, is idealogically lopsided. Dana60Cummins, it is very apparent from your contributions to this article, this talk page, and your own talk page that you don't like EGR on diesel engines. That in itself is a problem; theoretically it should not be possible to determine a good editor's personal preferences and opinions from the contributions s/he makes. At least you've supported your assertion with a couple of refs, which is good, but I'm afraid the notion just doesn't hold water that diesel EGR is a nefarious, thoughtless mistake forced on a sheeplike industry by ignorant morons at the EPA. In the very large and well-documented context of the overall vehicular-emissions cleanup effort over the last fifty years, that idea just isn't very sturdy. EGR gives benefits on diesel engines or it wouldn't be there. Whether those benefits are as large as stated and/or are equal to whatever drawbacks—those are debatable points, and as long as there's reliable support for assertions one way or the other, there's nothing wrong with including them in this article. But this "diesel EGR is bad" stuff just doesn't cut it on its own. — Scheinwerfermann T· C 02:52, 16 May 2011 (UTC)
″Exhaust gas—largely carbon dioxide and water vapor″ - well that might be true if the combustion was taking place in an oxygen enriched atmosphere. With combustion in air (or in air with recirculated exhaust gases) the exhaust gases will be predominantly nitrogen - I think between 73.8% and 79% depending on how much oxygen was consumed. — Preceding unsigned comment added by 2.125.187.47 ( talk) 18:27, 27 September 2015 (UTC)
Alexander Noé ( talk) 19:23, 17 October 2023 (UTC)
Although it wasn't designed as such, Exhaust pulse pressure charging is probably a form of Exhaust gas recirculation. Biscuittin ( talk) 22:01, 27 April 2015 (UTC)
Does anyone know the peak temperature that is generated with, and without EGR? That is NOx generating temperture? There is discussion in RP-1 about NOx generation from rockets. Gah4 ( talk) 18:02, 6 August 2020 (UTC)