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My silicone hoses have arrived. But I have decided not to use them. (0.8mm ID)
I shall be using a 3mm OD 2mm ID PTFE hose instead.
My reasoning behind this is, I do not want to pressurize the system with a restive/restrictive path. I have made the assumption that the steam is at 100 deg C. And the hotter i make the steam, the less i will need to inject it. BUT I want to inject steam, at least the water component, injecting water should have a benefit (or at least I believe so, and the papers indicate so {For petrol/gasoline it helps atomization/vaporization of fuel, i am running LPG and water is still mildly beneficial for some unknown reason to me. })
Adding a restriction will increase the pressure in my vaporization chamber, which will lead to higher temperature steam.
If the temperature is at 1 atm, the water will turn to steam at 100 deg C.
Steam has a thermal conductivity of 0.0184 W/(m K) at 100 deg C.
Air has a thermal conductivity of 0.0314 W/(m K) at 100 deg C.
So... steam is a bit more than half the conductivity of air. This means that it is a pretty good insulator which means that the steam in contact with the metal will insulate the steam that is not in contact. In addition my hoses are still pretty small, so the velocity of the steam will be high, giving it not much time to dwell in the vaporization chamber.
Sanity check:
1 meter of 2mm id hose -> volume of 3.14 * 1000 mm = 3140 mm^3 = 3.14 cm^3.
30 cm of 1cm id pipe -> volume of 3.14 * 30 cm = 94.2 cm^3
Although nothing is set in stone, these appear to be the specs. So 97 cm^3, lets just call it 100 cm^3.
Now, when the system stops, this volume will be filled with steam.
Steam at 100 deg C (boiling point) has a density of 1.69 m^3 / kg. -> 1690 cm^3/gr
Soooo my 100cm^3 of volume filled with steam will condense in to 1/17th of a gram of water when the engine cools down. This is not really a big worry for me.
Lets assume that I am injecting 1/10ml of water and 2ml of water per sec.
1/10 ml of water (for water 1ml = 1gr) will occupy a volume of 169 cm^3. {about half a coke can for those that do not follow} This is amount of steam injected. So this is 1.69 time the total volume of my chamber. So every second all of the chambers contents will be ejected in to the manifold as 1.69 times its volume of new steam is generated.
At 2ml/s that is ~3400 ml of steam (3.4 liters gas volume) passing through per second. 34 times the volume of the chamber. With such high volumes, the velocity will be high and the high velocity steam may bring with it some unvaporized water. I am not at all an expert in this domain it is just a gut feeling that i will have to test out with the system if anyone does not have any insight on this.
So from these calculations i can conclude that dwell time, or the steam dicking around in the vaporization chamber and super heating will not be an issue for me.
However, with this much gas generation, keeping my vaporization chamber (pipe) up to exhaust temp may be a concern.
The original idea was to have a very small hose that would have high pressure steam therefore high exit velocity which would help with the mixing, this is not my way of thinking now.
PS: all calculations are done in my mind on the fly whilst typing, so there may be some errors.
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