Difference between constant speed and variable speed engines 4

[arotester]

Hello everyone,


I wanted to what exactly is the difference between the constant speed and the variable speed engines?
I am inclined mainly on Diesel engines.

 

[ivymike]

This is true, in that these applications tend to run at a constant speed for an extended period of time. However, the speed setting may be changed from time to time in order to adjust to changing operating conditions or external demand.

That's not what I meant - there are actual constant speed diesels for mechanical drive applications which have a non-adjustable fixed operating speed (1800 rpm in one example). These engines can only operate at low idle (for warmup and shutdown) and the rated speed. The engine software and legal requirements (emissions certifications) prevent operation at any other speed. Lest you go away thinking that emissions certifications were the only thing that drove creation of these engines, the application existed before the emissions-certified engine was developed (or it wouldn't have been).

A constant-speed engine can be tailored to give better transient load response at the desired operating speed, which helps in gensets and also in some mechanical drive applications.