I know that, the colder the woodgas is when it enters the engine, the more “power” you get. My question here is: Has anybody been measuring the incoming gas temperature with a thought to determining an acceptable RANGE for reasonable operation? Or at least a “TNE” (Temperature Never Exceed)?
As some of you know, I am still messing around with a Chinese JXQ-10 gasifier.
See: http://www.spaco.org/JXQ10A.htm
In case you are not familiar with one.
The input side of the filter mechanism is a 4.3 gallon cooling tank that normally is fed by cool water to cool the gas coming out of the reactor. Depending on the temperature and flow of the incoming water, one has a wide range of control of the output temperature of the gas produced. At a flow of about 1 gallon per minute of 50 degree F (well) water, I can easily keep the output gas temp well below 100 degrees F.
Since I live in a part of the USA (west central Wisconsin) where it is below freezing about half of the year, I decided to add a radiator to cool the liquid in the cooling tank in a more-or-less closed circuit way. I suppose it will be similar to what “Tom Diesel” has done. My cooling system will hold 5 or 6 gallons of auto type antifreeze/water, so I won’t have to drain it after each winter run. I am using a small “Johnson pump” to move the fluid since I don’t have the expertise or interest in making a thermo-siphon setup.
All that said, I will have the capability (I think) to control the output gas temperature over a wide range but I don’t want to waste resources on fans, etc., if I don’t need to.
So------ I have set a target of 104 Degrees F max for woodgas coming out of my filter assembly as it goes to my 6 foot long induction tube to the engine. How much more power will I get if that temp is only 90 degrees F? Is it a big enough difference to worry/do anything about?
Hey PeteS.
Figure a max in gas ternperature of ~175F degrees. Past that you will get into oil buring/carbonizing off the intake valve stem issues.
Acceptable range will vary a lot depending on the engine, user, time of year and circumstances. When I’ve pushed up to 200+F gas was when oil vaporizing/carbonizing problems did show up.
As living in an air condnesing wet climate 10 months of the year I have to have gas temps of at least 130-160F and operate MUCH better with matching heated engine air. Otherwise I air condensate moisture build up too badly in the mixers - collects soot. 34F to under 50F ambient then I also have flow valves/throttle plate “icing” “frosting” problems. 2 months of the year I am fine with cooler gas and ambient air temps.
Your 6 months frozen air will be much more freeze dried low humidity.
Mr Waynes air cleaner based mixers are parked on top of a WIDE, all warming V-8 engine. A sticking out away single cylinder engine mixer will run much cooler.
Always the Depends, Depends, Depends in woodgasification and Life.
This colder air is more engine power useage is for seasonal hot rodding and limited racing. Fellows here doing that spend a lot of bar and cafe sitting time waiting for their engines rising heats to warm up thier then air flow frosted up non-airheated carburetors so their vehicles will run again. Some fuel injection systems very sensitive to throttle body frosting also. I’ve seen these be engine coolant flow plumbed to warm them.
ALL commercial made light aircraft DO air pre-heat. Snowmachine and artic used chainsaws air pre-heat to prevent carb frosting and warm the fuels.
Thank you guys for your replies.
Now I see that I probably won’t hurt anything with a fairly wide range of incoming gas temperatures, but I was still wondering about the difference in the AMOUNT of gas (density) that would be getting into the cylinders as the incoming gas temperature rises. That is, “how much POWER will I lose as the temperature rises?”
I did some checking and the answer appears to be:
“there’s about a 12% drop in gas density from 68 degrees F to 140 degrees F.”
I’m no scientist or engineer, so I stand to be corrected if this is not right, but I used these two websites to get the data: http://yeroc.us/calculators/gas-density.php
-for the density info
-to convert degrees Kelvin to degrees F or C.
I looked at the density changes for 3 gases to make this proclamation:
-Air
-Carbon Monoxide
-Hydrogen
I was surprised that the density change “constants” for all 3 were almost identical, but that will make it easier for me in the future.
Conclusion:
There are enough variables in woodgas making, handling and combusting that this 12% change in density over that wide a range of temperatures is not a cause to lose any sleep over.
Hi Pete; Just wanted to say that I agree with you. Heck, In the South, metal containers without any fire to cool at all might be 150°-180°F by just being in the sun. So really hard to get gas very cool in the summer.
Thank you for the temperature versus volume vs power table.
It appears that, in my case, I am unlikely to see a change in engine power of much more than 10 or 12 percentage points even if I allow the filtered gas to get a little hotter than I have been allowing.
