Gas engine emissions: dependence on CO and H2?
Good day,
I don't want to delve too deeply into emissions formation with my question. I conducted an exhaust gas measurement test on a gas engine. I first ran it at lambda 1.8 and then at lambda 2.4. As expected, the measurable CO concentration is lower at lambda 1.8 than at lambda 2.4. However, as the CO concentration increases, so does the measurable H2 content in the exhaust, which is what the measurement at lambda 2.4 showed. But why? I can't really find anything about it online. Perhaps someone can help me.
(No Ratings Yet)
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So I don’t know how to use engines and burns right now (burning chemistry is a rather complex issue). My guess would be that you no longer have stable combustion at too high Lamda values, which can lead to all possible side reactions.
What exactly did you use as a fuel? And if I understand it correctly, Lambda 2.4 has both the CO and the H2 value higher or higher?
the engine ran with dry natural gas. And exactly, both the H2 and the CO value rose with increasing lambda
Could I imagine that in the case of excess oxygen, any radical reactions prevail, just because you can no longer saturate the oxygen with fuel gas. So the oxygen attacks the same methane molecule rather than another. That would be said to be salopp, each O takes what it can get and “ruffs” the methane apart, so that then more CO and H2 are produced instead of CO2 and H2O.
The dependence between CO and H2 in the emissions of a gas engine can be explained by the relationship between the Lambda control and the type of combustion. During operation with a lambda setting of 1.8, more oxygen is injected into the engine than with a lambda setting of 2.4. This leads to a cleaner and more complete combustion, which leads to lower CO emissions, but also to higher H2 emissions. If more oxygen is present, the hydrogen gas (H2) can be oxidized better, which leads to higher H2 emissions.
Lambda describes the air ratio and the higher this is, the more air, so also O2 is fed to the combustion I thought? the engine is operated
I would not answer the question. This reads again as if someone just gave your question to the ChatGPT.
Lambda is actually a measure of the air ratio in a petrol engine. There is the ratio of actually inhaled air compared to the optimal amount of air needed for complete combustion. A value of lambda 1.0 thus means an optimally adjusted air-fuel ratio. A value of lambda greater than 1.0 means that too much air is present in relation to the fuel and the motor is operated “magerer”. A value of lambda smaller than 1.0 means that too little air is present in relation to the fuel and the engine is operated “greaser”.
that you are right to my statement, which led to my question