Quote:
Originally Posted by serialk11r
At any rate something like 30% of the heat energy is leaving the tailpipe at temperatures around 400-700 (or higher, which is kinda bad but it happens) C. The cooling system runs at 90-100C, and the engine internals are kept well below 200C, and the flame front shouldn't be hitting the piston early when temperatures are highest on a good combustion chamber design. The higher the temperature of the heat source the easier it is to get power out, so you can see why people are turning to the exhaust for waste heat recovery.
|
Just to clarify, by "engine internals are kept well below 200C", you mean the bottom end (and other moving oil-fed bits)...?
Obviously the inner walls of the cylinder are at considerably higher temps and, going back to the 6-cylinder engines for a moment, the ability to make work (and negating the cooling cct) is dependent on the high temperature (and quantity of heat) of the cylinder walls and piston crown.
This issue about water injection being akin to a steam engine does seem to come up quite often, but as has been said it is completely unfounded. However, the arguments for using W.I. that do make sense are all founded in cooling the charge (whether for power[turbo'd] or efficiency[pumping-loss]), yes?
So why not just use up the water as an
external, evaporative cooling agent prior to the charge entering the cylinder? Would the effects be the same or better (providing the charge is not so cool as to deter atomisation)?