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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. J

    Gas valve on fire?

    Hi everyone, My customer has a gas fire (Gazco Logic HE fire, about 10 years old). It's a slide control fire. The fire has become difficult to light. One has to push a lot more firmly down on the control slide to get it to light. At which point, all is fine. The pilot is good, new battery...
  2. N

    Zero Governors and Gas Analysis

    Morning all, I am just about to begin doing more installs of combi boilers, I am gas safe but just never really done a lot of installs due to being busy with general plumbing and bathrooms. One question that i have is, when checking working pressure on a boiler with a zero governor what sort...
  3. B

    Motorised gas valve for cooking gas bottle?

    Hi, We are designing and building cooking gas bottles with electronics controlled valves. These are for kids camping chalets. Its purely a safety feature because its kids. As you can tell, there is no big market for this product, its just to get these kids out camping. System description: So...
  4. E

    Why does gas valve need to be changed after 2 years?

    We have a baxi boiler that's serviced every year It's 6 years old and had a gas valve replaced in 2020. A British gas engineer serviced the boiler last year and left it leaking water inside it was all dripping out of the boiler. Another engineer had to come back and fix it. Before he came back...
  5. T

    Glow Worm 45/60CF gas valve

    Hi All, I am looking to see if I can find a compatible gas valve for my Glow Worm 45/60 boiler part number UK48RBB01 any help would be much apricated.
  6. H

    Gas Valve - Inlet Test Point and Burner Test Point screws

    Hello, Some advise please. Doing my gas course so I have taken a few boilers home to practise taking them apart so I can understand more how they work. For the gas valve in a Worcester boiler I got my hands on I have been trying to undo the screws for the Inlet test point and Burner test...
  7. H

    gas valve creates clanging noise

    Looking for some advice on how to get rid of some noise our gas valve is making. Our natural gas fired boiler uses a Honeywell VR8304M4507 gas valve. The boiler is in a 1200 sq ft unfinished basement. The gas feed enter the home at one corner and the boiler is in the opposite corner. So iron...
  8. M

    Boiler fault. Gas valve ?

    Evening all, I am the unfortunate owner of a very large gravity fed floor standing gas boiler. A few days ago the boiler decided not to come on when there was demand. The pilot light remained on. After a quick look over and attempted relighting the pilot light went out and would never stay...
  9. P

    Honeywell gas valve shutting off

    Type4600 valve shuts a minute or so after burners ignite. Have tested two thermocouples (existing one and a replacement) and getting 25 mV from each. Is there any additional diagnostic I should consider before sinking cash into new valve?
  10. M

    Quinta Pro 90 setting up and adjusting a new gas valve

    Looking for anyone who has had issues setting up and adjusting a new Honeywell gas valve on a Remeha Quinta Pro90 gas boiler ! Problem is getting the boiler to light as a starting point before adjusting to correct settings
  11. Atanas Peev

    Gas valve Vaillant eco tec pro 24

    Hello any with experienced with gas valve low voltage The boiler is Vaillant eco tec pro 24 I’ve got a code F61 and voltage to gas valve solenoid is 4.51v dc Regards Atanas
  12. quality

    GLOWWORM 800869 GAS VALVE 100F HONEYWELL VR4601

    Anyone got a gas valve for a fuelsaver 100f as per above. System is linked to a log burner so would like to fix the old girl as shes only 30 years old
  13. M

    Gas valve for hob behind cupboard.

    When installing a gas hob the required isolation valve usually falls behind the cooker. That is removed by unscrewing 4 screws. I'm wondering if its seen acceptable by most to use a compression gas isolation valve in such a position. . Thanks
  14. D

    Can you break a gas valve with LDF?

    Hi all, I serviced a boiler last week, adjusted the gas valve (a tiny little tweak) then gave a tiny little skirt of LDF on the test points. Just had to go back there and boiker only running on half. I think one of the sololoids on gas valve is not opening. Question is, thus just...
  15. J

    Gas leak on fire (after the gas valve)

    How far do you all go during servicing to test for leaks on gas fires? Up to the gas valve is easy -- drop test/ LDF on joints. But I had a gas fire this week, leaking from where the control 'pusher' goes into the gas valve. Visually it looked OK. But after smelling gas while using the fire...
  16. D

    Burnt out Solenoid on gas Valve Greenstar 30 i Erp

    Green star 30 i Boiler has Burnt out Solenoid on gas Valve. Worrying thing is the boiler didn't turn off and the plastic coating the solenoid kept smouldering. Has anyone had/seen this before. I am a Physicist, is coating a solenoid with plastic normal? This is/was obviously a fire hazard...
  17. Andyh

    Glow worm bbu gas valve fail ?

    Hiya fella, thanks for the acceptance, I'm traditionalself taught as my company just did installs However I'vegot a a glow worm 56 bbu, pilot working fine (according to customer) but no main burner .. what's thegeneral testing of gas valveis it 1. Interupter 2. Thermostat 3. Resistance on...
  18. B

    Potterton Prima Gas Valve

    Just been to look at Potterton Prima that’s not lightning. Boiler goes through ignition sequence but there’s no gas coming through the valve to light the pilot. There’s 240v on the white wire going to the gas valve but nothing on the black. I presume there should be 240v on the black as well. If...
  19. Gasmk1

    worcester 24/28I junior gas valve

    does anyone want this gas valve never fitted just pay for postage or you can collect from warrington
  20. Harvest Fields

    Vaillant Gas valve on install

    Just had my first ever Vaillant issue on install. 17.5mbar at boiler 12.5 at gas valve. :eek::eek::eek:
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