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In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NO x ) emissions reduction technique used in petrol/gasoline, diesel engines and some
hydrogen engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. This dilutes the O2 in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in-cylinder temperatures. NO x  is produced in high temperature mixtures of atmospheric nitrogen and oxygen that occur in the combustion cylinder, and this usually occurs at cylinder peak pressure. Another primary benefit of external EGR valves on a spark ignition engine is an increase in efficiency, as charge dilution allows a larger throttle position and reduces associated pumping losses. Mazda's turbocharged SkyActiv engine uses recirculated and cooled exhaust gases to reduce combustion chamber temperatures, thereby permitting the engine to run at higher boost levels before the air-fuel mixture must be enriched to prevent engine knocking.In a gasoline engine, this inert exhaust displaces some amount of combustible charge in the cylinder, effectively reducing the quantity of charge available for combustion without affecting the air-fuel ratio. In a diesel engine, the exhaust gas replaces some of the excess oxygen in the pre-combustion mixture. Because NO x  forms primarily when a mixture of nitrogen and oxygen is subjected to high temperature, the lower combustion chamber temperatures caused by EGR reduces the amount of NO x  the combustion generates. Gases re-introduced from EGR systems will also contain near equilibrium concentrations of NO x  and CO; the small fraction initially within the combustion chamber inhibits the total net production of these and other pollutants when sampled on a time average. Chemical properties of different fuels limit how much EGR may be used. For example methanol is more tolerant to EGR than gasoline.

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  1. Robert Tyrrell

    Gas Valve adjustment

    I know that I should remember all this stuff but at the moment I kinda need a refresher if there's anyone willing to remind me? I would like to be reminded of how the gas valve adjustments affect the CO & CO2 readings as I think that I might have a dodgy sensor on my fga, despite the fact that...
  2. M

    leak on a g-star 30si....water around gas valve connections sending it to fault

    hello lads, not been on in a while, how ya'll doin?? I went to a g-star 30si the the other day where water had somehow gotten around the connections on the gas valve sending it into fault mode....I cant see any obvious leaks though!! there's water lying all round the bottom of the heat ex...
  3. A

    glow worm 85 -100 need gas valve

    Thanks can any one help in sourcing this gas valve for this old boiler? Or if anyone can repair it...has a slight leak.I can mail picture if it helps Tha
  4. M

    Gas valve?

    Another question lads sorry. When my colleagues alter the gas/air ratio on a combi they only use a analyser but looking through some makers instructions it's states that a manometer should also be used. I know MIs have to be followed but in this picture What is the p in and P out? Are these the...
  5. S

    Worcester Greenstar 30Si Gas Valve changeover

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  6. B

    Sigma 845 gas valve question

    Hi all, just wondering if anybody could tell me is it a grub screw in the port above the one for the inlet pressure on the sigma 845 gas valve? I think I have a leaking valve and it seems to be there. It looks like a grub screw although hard to make out, but my Allen key won't turn it. Does...
  7. I

    Glowworm Chatsworth gas valve wanted

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  8. B

    Lost screw for sigma 845 gas valve

    Hi all, Was checking inlet pressure on a vokera compact 24 and I somehow managed to loose the screw that you loosen to check pressure. Is there anywhere I can just get the screw on its on? I do not know how the screw came out and I searched high and low but can't find it, feel like a complete...
  9. Y

    Aga gas valve Junkers

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  10. Y

    Aga gas valve Junkers

    Hi all i've got an Aga with a Junkers gas valve. My local engineer came round to service and light the Aga today and found the valve has a gas leak. he informed me that this is very common with the Junkers valve and the usually cause of action is to replace it at a cost of £700. he also told me...
  11. T

    Vokera Compact 28 Gas Valve Fault

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  12. B

    Possible gas valve passing on ideal isar - but why is there no drop??

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  13. M

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  14. B

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  15. L

    Resistance readings on the solenoid for gas valve on remeha avanta plus 28c boiler

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    • lambchop
    • Thread
    • avanta boiler gas gas valve oil plus readings remeha resistance solenoid valve
    • Replies: 0
    • Forum: Plumbing Jobs | The Job-board
  16. E

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    Hi, on the old 28CDI anyone know what voltage DC you should expect at high and low flame?
  17. C

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    Need a gas valve for this model, obsolete from manufacturer now if you have a brand new one(bonus) or a good second hand working one Please let me know Gas valve model number is 004050 fits Ideal Mexico super cf 40/60 GC Number: 41 415 27
  18. S

    Ideal e type rs100 Gc no 41/399/67 any one know if the gas valve can still be had?

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  19. B

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  20. stani

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