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Just to clarify the idea
In the steam cylinders
Compression stroke
Exhaust gas from the combustion cylinders enters steam cylinders
In compression T(final at end of compression)= 600K(tinitial)*(9(compression ratio))^(1-(1/1.3)), 1.3 = adiabatic index
=~1000K (very hot). Assuming exhaust from combustion cylinders is 600K
(Pumping losses will be high on the compression stroke(having to compress a hot gas), but would be more than made up for on the expansion stroke)
When the spark plug would normally fire, say 10BTDC the water injector injects a tiny amount of water which instantly becomes superheated, creating really high pressures.
Cylinder pressure can be controlled by amount of water injected.
Could a petrol engine withstand these pressures? or could the water injector be controlled well enough so that pressures don't exceed.....
Not much water will need to be injected/ used at those high temps/pressures, and hence open loop water system should be ok
Expansion stroke
The superheated stream expands over the 9:1 compression ratio. Sterling and steam engine generally have low compression ratios anyway there for i assume the majority of the pressure energy will be extracted by the expansion stroke.
"As for the steam compression stroke I don't think..."
I wouldn't be compressing any steam, steam gets injected at end of compression stroke
"Oil contamination from steam blow by."
Will this be problem if steam is superheated? At the bottom of the expansion stroke the steam may be wet steam. Pressures shouldn't be really be large enough at bottom of stroke to blow steam past piston seals and contaminate oil.
I like the idea or being able to supercharge the combustion cylinders to balance steam cylinder torque against combustion cylinder. Or this could be also achieved by venting some of the exhaust, but this results in lower efficiencies.
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