Is measuring % of Ammonia relevant?

[RobHawker]

Hello all, for SCR equipped engines we have been asked to consider showing % of free Ammonia on our SP 9550 Diesel gas analyser - when testing emmisions at the exhaust pipe outlet.
Our designers think that that sufficient information is present on the 5 gases we already measure HC, O2 and NOx together with CO and CO2; their belief is that this is enough to understand the internal state of the engine, and that adding Ammonia measurement may confuse diagnosis further. I wonder what the thoughts of those using this forum are on this extra reading, as this may help guide our R&D decision on the matter. Regards Rob

[pallavkarsameer]

Hello Rob;

If I may add that measuring HC, CO, CO2 and O2 merely indicates the combustion quality of the diesel engine operation, and with EGR it is expected that NOx should go down, however, NH3 injection amount is critical to minimize NH3 slippage from the exhaust. One needs to quantify the amount of NH3 slipped in the exhaust at different exhaust gas temperatures (depending on the driving and load conditions) which in-turn assists in estimating NH3 consumption, on-board NH3/Urea storage etc. during a cycle-run.

Your product will be greatly benefited if you can incorporate NH3 measuring sensor which would be resilient to the presence of H2O. In my humble opinion, NH3 injection amounts should not be same/constant at different driving/operating conditions, and without actually being able to measure NH3 on-board or by means of an analyzer, we are missing a critical information.

I hope this helps your developing team. All the best!

Regards
Sameer Pallavkar

[RobHawker]

Hello Sameer,

Many thanks for your considered response - it is greatly valued; I will pass your thoughts on. Regards Rob