Quote:
Originally Posted by oil pan 4
After me and my engineer buddies got lost in steam tables, ideal gas law, studying the lubercation properties of steam/water to figure out why water injection boosts fuel economy and power of diesels and gas turbines we setteled on this:
Water injection - EcoModder |
That is correct. The theoretical maximum efficiency for a Diesel cycle engine depends both on the compression ratio, and on the inlet and combustion temperatures. Lower the inlet temperature, such as with flash evaporation of a fine water mist, and Diesel efficiency goes up.
The theoretical maximum efficiency for the Otto cycle (gasoline) engine depends solely on its compression ratio. Lower the temperature of the inlet air, and the efficiency is left unchanged.
Quote:
Originally Posted by oil pan 4
Its going to take a lot of work, lots of testing and lots of tuning to produce a positive result on OE gas burners. But you can try.
I bet I can do it, but don't have a way to test it, yet.
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Aside from the obvious benefit of moving the conditions of the combustion chamber away from detonation and pre-ignition, hot water injection could be a way to permit throttling with a lower intake manifold vacuum. Normally, gasoline engines require the use of a vacuum in order to throttle the air going into them. High vacuums take energy to create and maintain, and do not actually push the vehicle down the road. Higher vacuums require a larger percentage of engine power to maintain, than do lower vacuums. If hot water injection were used in this instance, flash evaporation of the water could contribute a pressure increase inside the intake manifold, while leaving the oxygen content of the intake manifold unchanged. This would allow the engine to use less of its developed power to maintain the intake manifold vacuum, and use more of it to actually propel the vehicle down the road.
Now, inject too much water, and you run into ignition quenching issues. Inject more water than that, and you run the risk of hydrolocking the engine. I'm not so concerned about water vapor in the combustion chamber possibly leaking out and contaminating the oil, since exhaust has plenty of water vapor in it already.
This was what I was hoping to see with
tjts1's logs.