Clean Emissions = Higher Operating Temp ??
Clean Emissions = Higher Operating Temp ??
(OP)
Hello,
I was wondering if there is a general trend in engine designs about heat rejection versus engine combustion efficieny. I have heard it both ways = cleaner burning engine runs hotter and cleaner burning engine runs cooler.
Can anyone shed some light on this question?
Thanks in advance for sharing your expertise.
Joe
I was wondering if there is a general trend in engine designs about heat rejection versus engine combustion efficieny. I have heard it both ways = cleaner burning engine runs hotter and cleaner burning engine runs cooler.
Can anyone shed some light on this question?
Thanks in advance for sharing your expertise.
Joe





RE: Clean Emissions = Higher Operating Temp ??
Some design parameters tend to simultaneously affect engine out emissions, heat rejection and exhaust temperature in a favorable direction (e.g. fast burn combustion system), while others tend to move one or two of these variables in a favorable direction while altering the remaining variable(s) in an unfavorable direction (e.g. compression ratio, spark timing, thermostat setting).
RE: Clean Emissions = Higher Operating Temp ??
Using such things as EGR for dillution, to displace some of the O2.
RE: Clean Emissions = Higher Operating Temp ??
Coolant temperatures being higher can effect fuel economy in 2 ways though.
Less heat and energy loss to the atmosphere.
Better aerodynamics as the radiator can be smaller or require less airflow over it.
Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
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RE: Clean Emissions = Higher Operating Temp ??
The future says that they will go to the control of both intake and exhaust cams with an effort to increase power over a wider band and use cam timing/phasing change to get rid of the present EGR method by taking advantage of cam phasing to reduce NX output to the cats.
RE: Clean Emissions = Higher Operating Temp ??
RE: Clean Emissions = Higher Operating Temp ??
It has also been reported that advancing the ignition timing will increase the NOx emission. This is against the belief that higher exhaust temperature will cause higher NOx emission. Any comment about this?
RE: Clean Emissions = Higher Operating Temp ??
I will take a SWAG at that. The increased exhaust temperature, when timing is retated, is due to the incomplete combustion being pushed out the exhaust. I would guess that due to this incomplete combustion that less NOx is formed. Though, in my seach on this subject I found this paper http://w
RE: Clean Emissions = Higher Operating Temp ??
Sounds good to me.
Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Clean Emissions = Higher Operating Temp ??
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RE: Clean Emissions = Higher Operating Temp ??