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Hi everyone,
First of all, my answer to the question posted - YES. Running at lower rate can cause the damage.
All correct. TBN, "A"/"E" categories, sulphuric acid, thermical expansion of parts, etc.
Additionally, I'd like to divide engines into groups, differentely affected by "low load":
1. Running at constant speed, as gensets, CPP applications.
2. Electronic engines.
3. Running at variable RPM's.
Group Nr 3 is of a "higher risk".
The reasons:
1. Everything, what was already mentioned by other forum members.
2. Low piston's speed allows piston rings getting stucked in grooves.
3. Injection's timing instability.
And some other factors abt running at low load, what were not mentioned yet:
1. Charge air temperature.
Of course it's low at low load... and this affects combustion dramatically for all groups.
There are a lot of marine applications, where charge air is even preheated up to 60-70 deg C during running at lower rate.
This improves quality of combustion.
2. Injection timing.
Running at different RPM, timing may shift to "EARLY" or "LATE" side of diagram.
Of course, depends on factors like a plunger configuration and electronic timing (if any).
But this can cause an improper combustion as well.
3. Fuel atomization.
If it's bad, don't be impressed of having problems.
P.S. If interested, I can post some of my recent diesel engine's diagrams,
performed with digital engine's analyzer.
Regards,
Andrei
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