It is well known and understood that the oxidation mechanism of H2 (and CO as well) is a fundamental subset of the oxidation mechanism of every hydrocarbon (see e.g. Law - Combustion Physics). In principle, every kinetic mechanism that describes a specific hydrocarbon oxidation should be able to describe hydrogen oxidation. However, this is true only in hierarchically-built mechanisms. Often, kinetic schemes are designed and optimised, i.e. reaction rate parameters are fitted to experimental data, to reproduce experiments involving the hydrocarbon of interest, in specific experiment configurations and operating conditions. Hence, the accuracy of the sub-mechanisms is not assured, albeit it is very likely that the hydrogen sub-mechanism would yield satisfactory results, being a fundamental part of the whole picture. But don't take it for granted, it depends on what physical feature you are looking for.

Skeletal mechanisms add another layer of uncertainty, since they are obtained by discarding a number of features of the detailed mechanism. But again, since H2 oxidation is a building block of every hydrocarbon oxidation, the main H2 reactions should have been retained in the skeletal mechanism.

In the end, I would go back to the detailed mechanism, look for its validation and performance (was it validated also against H2/Air experiments?), then understand what kind of simplification procedure was employed (was H2 chemistry targeted? Was it validated against the detailed mech in H2 problems?), and eventually compare the skeletal and detailed mechanisms (and maybe also an H2-designed mechanism) in a prototypical problem (a 1-D premixed flame?) with hydrogen as fuel.

Interesting

https://www.sciencedirect.com/search?qs=H2%20oxidation%20mechanism%20as%20a%20submechanism%2C%20for%20a%20H2%20combustion%20simulation%20with%20CFD&show=25&sortBy=relevance

It would work quite well in general. I can answer in greater detail if you tell me what specific mechanism it is.

I dont think that but in general you can the methane-air chemical mechanism enriched by the H2 with percentage .( exemple h40%ch460%).

It is a skeletal mechanism, which has 60 reactions and 17 species. It quite works and matches well with my experimental results. I suspect if i can use it for a h2 enriched methane mixtures?

Dear Kemal,

As per the information provided by you. This mechanism seems to be simplified kinetic mechanism for methane-air combustion. I assume it to be premixed combustion. As oxidation of most of the hydrocarbon fuel goes through production of H2 and CO as intermediate. So for accurate predictions of methane oxidation, the oxidation pathways of H2 have to be incorporated accurately. So, I think the mechanism which is used by you will give reasonably accurate results for premixed combustion.

Dear Syed Mughees Ali,

Thank you very much for your comments.It is true that this mechanism is a simplified one, which is also called methane-air extinction mechanism (opposed flow flame). So i am using it for the non-premixed methane-air combustion simulations, which quite works well with the experimental results.

Dear Kemal,

Can you provide more information about this mechanism. For example what procedure is followed in developing this mechanism. Is this mechanism validated/optimized using criteria like laminar flame speed, autoignition characteristic and ignition delay. Besides these three is extinction strain rates are also used for optimization of this mechanism. If possible provide a link of this mechanism.

It is well known and understood that the oxidation mechanism of H2 (and CO as well) is a fundamental subset of the oxidation mechanism of every hydrocarbon (see e.g. Law - Combustion Physics). In principle, every kinetic mechanism that describes a specific hydrocarbon oxidation should be able to describe hydrogen oxidation. However, this is true only in hierarchically-built mechanisms. Often, kinetic schemes are designed and optimised, i.e. reaction rate parameters are fitted to experimental data, to reproduce experiments involving the hydrocarbon of interest, in specific experiment configurations and operating conditions. Hence, the accuracy of the sub-mechanisms is not assured, albeit it is very likely that the hydrogen sub-mechanism would yield satisfactory results, being a fundamental part of the whole picture. But don't take it for granted, it depends on what physical feature you are looking for.

Skeletal mechanisms add another layer of uncertainty, since they are obtained by discarding a number of features of the detailed mechanism. But again, since H2 oxidation is a building block of every hydrocarbon oxidation, the main H2 reactions should have been retained in the skeletal mechanism.

In the end, I would go back to the detailed mechanism, look for its validation and performance (was it validated also against H2/Air experiments?), then understand what kind of simplification procedure was employed (was H2 chemistry targeted? Was it validated against the detailed mech in H2 problems?), and eventually compare the skeletal and detailed mechanisms (and maybe also an H2-designed mechanism) in a prototypical problem (a 1-D premixed flame?) with hydrogen as fuel.

Dear Kemal,

Please have a look at Fig.2 where a higher C mechanism (n-dodecane - C12H26) was used for lower one (CH4).

Article Comparative study on chemical kinetic schemes for dual-fuel ...

Similarly, you can use CH4 mechanisms for H2. Of course I recommend some validation before your final results as some of reduced mechanisms are aimed for a certain range of conditions (T, P and phi).

I hope this helps.

Mahdi

hello every one ,can anyone tell me how i can get experimental data of NOx emission of pre mixed gas turbine combustor .

Dear Naveed,

As per my understanding you want to measure the NOx in postflame region. For that purpose gas sampling probe attached suction pump and flow control device further attached with a sampling bag can be used for sampling. After that gas cromatrograph can be use to analyse these samples. Also their are standard NOx dectects available which will give directly provide you the quantity of NOx produced.

Dear Syed Mughees Ali ,

I need to do Validation study of CRN+CFD by Using Ansyas Fluent and Chemkin tool,by getting simulation results from CFD Making a CRN (Chemical reactor networking ) using GR 3.1 mechanism and compare its result with experimental data of combustor available in public domain ,my question is there any link or source from which i can get experimental data of gas turbine combustor ,because i am new in this field and do not know about it more .

Dear Naveed,

PFA link that will be useful.

Article A Review of NOx Formation Under Gas-Turbine Combustion Conditions

Dear Syed Mughees Ali .

I have been readout this Review ,but the problem is i need some gas turbine combustor experiment result of NOx emission ,so i can compare my results with it .If you have some idea please help .

Dear Naveed,

PFA link

Article A reactor network model for predicting NOx emissions in gas turbines

Read the section where CFD results are compared with experiments.