--- Water injection VS Steam Injection ---

[dcb]

I would be happy to know what was the net efficiency gain was for starters

[Azmio]

calculated to be roughly above 70%. The thing is, many of the engine parts and simulation codes that I need are not available anywhere.

The trick is simple, minimize heat from going to coolant and exhaust gas. even if some escapes, absorb it using heat exchangers and inject the heated water back into the combustion chamber

you can even heat up the water to be injected using heat from your brake caliper. any increase even by 5 degree C will simply mean that the water require 5 degree C less to evaporate in the combustion chamber

[dcb]

Yup, it is interesting. Direct hot water injection. Hopefully nobody here still uses gasoline to heat up their brake calipers much , but I get your meaning.

I'm trying to envision it as integral to the cooling system, I don't think my engine's cooling jackets are ready for 1500 PSI though, but I suppose it doesn't HAVE to be pre-pressurized before the engine. The water could flow through the engine (and circulate as needed), then the pump then coil around the exhaust.

Course you might not have tested all these but anyway:


What operating range saw the most efficiency increase? high load/low/mid load, high/low/mid rpm?

What operating ranges was it impractical in? i.e. where it reduced power significantly or increased emissions too much?

Was this a diesel or gasoline setup or did you try both?

Lastly, is it bigger than a breadbox?

[Azmio]

since water is a good energy carrier, we just need to direct a small coolant hose to the brake caliper. This should be good for the future F1 cars.

You can have low pressure circuit for low temperature heat exchanger, but the moment it goes to the exhaust gas heat exchanger, it needs to be pressurized or else it will turn into steam. Pumping steam requires 10 times more power than pumping liquid water.

Considering that i draw oxygen from the pressurized oxygen tank, the peak efficiency is constant across engine load/rpm. it works very differently from regular car where the volumetric efficiency depends on engine speed, throttle opening, tuning, turbo, etc.

The vehicle needs to run with methanol or else the range is below the requirement. Assuming that we use the same composite tank for NGV, oxygen having almost twice the density of methane ensures plenty of oxygen to be available for every refilling. Other than that, high engine efficiency is a must or else the car wont be travelling far.

I used to work as a engine design engineer for a japanese oem and an F1 team. I have to say that once I develop compression ignition engine and understand its efficiency, i am a true convert of CI engine. Furthermore, i need the center of the combustion chamber for fuel injector, there is no place for a spark plug.

It's not as small as breadbox, but considering that the engine makes power in every revolution at constant peak torque even at low rev. I would say the displacement is really small.

[dcb]

so to get a %70 improvement you would have to absorb a lot of "waste" heat, which means you have to pump in a lot of water (without putting out the flame). What is the ratio of water/fuel approximately?

[Azmio]

not really, the trick is to absorb as much combustion heat as possible using the best cooling agent around because this will minimize waste heat going to the coolant and exhaust gas. The more heat is absorbed by water in the combustion chamber, the more it will expand to push the piston down.

Understanding that it's almost impossible to have 0 waste heat, the escaping waste heat can be recovered and injected back into the combustion chamber. You will also notice that I dont use a smaller steam turbine to capitalize on the recovered waste heat. My research made me believe that using a single engine but getting the most from every stroke is the way to go.

[dcb]

It is the first I've heard of it (not saying much there), but it makes sense. You give the fuel a chance to light, then add water.

Did your 70% net gain include brake calipers? Just curious because we don't encourage braking like a normal yahoo here. What would be the gain without that heat source?

[Azmio]

my calculation does not include any thermal energy from the caliper. That 70% comes only from "energy within the system".

For stationary engine, you can pack in lots of thermal energy from sun, geothermal, industrial waste heat, you name it. Anything that increases the water temperature counts. For normal steam engine, Water at 80C or 90C carries lots of energy but the enthalpy is low so you cannot do any work. Not anymore with this engine, just pack in whatever thermal energy that the water can carry and shoot it into the combustion chamber. Within milisecond the enthalpy of the water will increase by 20 times.

[Azmio]

oh by the way, most of other engines with water injection system inject water before ignition. To me, this is a real waste.

Instead, i have my exhaust valve timing strategy to control the effective compression ratio and the amount of exhaust heat to be trapped. At low or high load, i always have the optimum temperature for fuel autoignition.

Another thing, injecting water before auto ignition will disrupt the flame development. It's better that we wait until the chamber is optimally hot before we inject the water.

[Azmio]

the optimum water to fuel ratio for best efficiency, i need around 9.5:1 at 320C. Much of the water injected will be recovered once it is condensed.

9.5:1 at 320 C is difficult to achieve unless the vehicle is braking. For stationary engine with solar thermal, it's not difficult to get this.

try this link and it's free

http://www.engine-expo.com/forum_200...azmi_osman.pdf