neubie need engine size explanations
glow plugs
I'm glad to see you did your research with respect to glow plugs.
As an engineer with a chemistry background, here's my explanation.
Here's the quote you provided. I agree with everything it says.
Glow engines are a hybrid between diesel and spark-ignition engines in regards to their mode of operation. In a glow engine, the catalytic action of the platinum glow plug coil is what ignites the fuel-air charge rather than a spark or the heat due to compression of the mixture in the chamber. As a consequence, the compression ratio used tends to be higher than in a spark-ignition engine but lower than a diesel engine.
It does not refer to the platinum coil as a catalyst, but rather states the platinum coil provides a catalytic action. The catalytic action is the absorption and radiation of heat energy.
Glow engines do not use spark ignition and do not use "heat due to compression", but use heat radiated from the glow plug's coil.