Since there are a couple of threads going right now that discuss gas temperatures, I thought I’d comment about the air/gas stream going into an engine. I’m sure this has been discussed previously, but here goes:
As the gas/air mixture gets hotter, I think the molecules get farther apart, so less of them get into the combustion zone with each intake stroke. If this is true, cooler gas would produce more power for a given setup.
Personally, I have chosen 104 degrees F as the maximum temperature of the woodgas that I want going into my mixer.
After all, I doubt if most engines were designed to have incoming air be hotter than about 125 degrees F or so. And, even then, especially for gasoline engines, the evaporation of the gasoline at the carb venturi or injector is going to cool the mixture some more.
So, I am surprised to see others having tubes melt and even a blower catch on fire.
What am I missing here?
Dont forget water vapor. Steam injection is good if its a true injection system. It does not work just carried in the gas as it is displacing the air fuel mixture. Even outside air humidity effects this. There is also a point where steam injection will do just the opposite and cool the combustion process too far for it to be effective.
need to get your gas as cold as possible and as dry as possible. This is why I use multiple cyclone dryers on my systems.
On the WK’s that I have built and used the gas was outside temp by the time it reached the mixer on the charcoal unit i built it was that temp before it reached the hay filter And I only used a cyclone before that. If people are having cooling problems cyclones cool the gas really well.
Yes partly due to the amount of surface area the gas is exposed too as it whips around the body. But there is also a forced condensing process taking place as water is forced out of the gas.
Multiple cyclones would be much better than a single one. I run one, and it gets extremely hot, at which point, I don’t think it is working as a cooler any more. And with that heat, I have never seen moisture in the soot that I collect. TomC
Can you get your temps entering and exiting? Even though the cyclone itself is getting hot this may because it is extracting heat. It would be interesting too see your gas temps before and post. On the cyclone bank I see a dramatic difference from to the next. On the Flex Power Station I packed a third one in bank for the new revisions.
Sorry Matt, but I have gone down to two thermocouples in my system. I had nothing but troubles with those readers. I had a very elaborate counter flow heat exchanger warming my incoming air and cooling my gas but because of the poor readers, I never got any conclusive results on that. I have gone to a two channel thermocouple insturment for my temperature readings.
I will say on cyclones, it can not take anymore heat out of the gas than the surface of the cyclone can disapate. I like the idea of enclosing the cyclone so that you can heat the incoming air, or in my case, I want to re-heat the gas before sending it through a paper filter. That is one of those down the road projects. I have a couple of systems on the shelf, that I need to finish evaluating. TomC Ps; finns on the cyclone would help
Underwriter’s Laboratories used to define “too hot to HOLD your hand on” as 137 degrees F.
If I can’t use a thermocouple, I use one of the HF (or better) IR guns. Mine has a 1:8 reading field, so it averages what it sees in a one inch circle from 8 inches away. I’m sure you guys all know this, but it reads best on a black surface, so I spray a 3 or 4 inch circle of flat black paint onto the surface I need to read. Then I hold the gun within an inch or two of that surface to take a reading, just to make sure I am getting a good read.
I guess my point is that, just because a surface it “too hot to touch” doesn’t necessarily mean that its a big problem.
Pete Stanaitis
On topic of the maximum temperature of allowed intake flow . . . .
I have taken this at times up into lubrication problems at the exposed valve stems and upper cylinder walls.
By this factor alone you want to stay below ~170F.
You will want to match warm the engine intake air to the gas fuel flow temperature BEFORE into the intake. Not within the intake.
Otherwise you will have multiple condensation and soot dropping problems within the intake. Shoot for a 140F with system-in-useages usage float of +/- 30F around that 170F.
The plastics in modern engine intakes are rated to handle this 170-230F intake air.
S.U.
Interesting about the whereabouts uses of plastic. Intakes
never entered my mind!