When gasoline or diesel engines are converted to natural gas, one obvious result is the reduction in power due to volumetric loss and slower flame speed. In addition, the charge heating value is reduced from the sipping out of natural gas through the piston rings during compression stroke. All these lead to power loss.
The basic equations to balance forces should be similar:
The basic spring effect and half pressure*height as force/m circumference.
The limitation of peak temperature is important for NOx. As CH4 has a higher Cp/Cv than air and no latent evaporation heat it will even heat more than an air/gasoline during compression. This limits the allowable compression ratio .
There might be an effect of an average higher temperature of oil, and increase the leak flow.
It is very important to avoid CH4 leaks in nature as the equivalent greenhouse effect is 25 times more than C02. So lowering leaks and also the recovery from the crankcase to inlet is important.
A similar issue, I examined to modeling analyzing studies for using Ricardo-Ringpak software and Ansys-Fluent software. Provided certain improvements with some modifications on piston ring types, piston ring grooves, piston ring coatings. Nowadays, I am in the beginning of a study about dual fuel systems and effects of the engine performance.
Dear Taib,
You should look for the phenomenan of "blow-by' as it is called.
Dear Prof Bastiaans. Thank you, yes the phenomena is known as blow-by. I am still searching more about this in the literature. In my work at Cranfield University some years back, we found up to 20% natural gas blow-by through the ring-wall gap. This was significant loss and post safety concern in practice.
You can find answer for this question in report prepared by M.A.N, after tests 10 liters bus engine.
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