Hopper Liners

General Discussion
#21

Yo! its all good, love the exchange.
Having only 2000 miles under me belt and working with the wk cooler tube design it does bring up a question or two.
It would seem that the main purpose(s) of gas cooling / condensing is to prevent using btu energy to make steam and to minimize the water vapor content down stream. I realize that any design that is easily serviced or self cleaning would be a good thing. Is there such a thing as too much gas cooling in the hopper? What would be the criteria to evaluate how effective a particular design is? The cooling tubes on my unit are only 1" diameter and SS to boot so I dont have the same heat transfer value as carbon steel. I will still drain off about a gallon of condensate for every 50 miles. But that is no bench mark, too many variables. I’m using kiln dried hickory right now. My experience is only on one unit so I have no reference point.

I thought 60 was fast until I went 90 if ya know what I mean.

#22

One thing to keep in mind, is that condensation is largely driven by surface area. With the external tubes, each additional 2" pipe is equivalent to making the whole hopper 2" bigger. With 9 2" tubes, Wayne has the same cooling surface as a 40" diameter drum! I posted on this topic here: http://driveonwood.com/forum/1415

#23

Interesting concept Steve U. But I think it is very relevant. When building this last hopper with no upper gutter, and only 6 cooling tubes, (1-1/2" conduit), I actually did wonder what if I go to Waynes and he gives me some wet wood, will I be able to DOW home?? Ha! I’m not really worried, but more interested if I could tell a difference or not. So much to learn and try for myself, with my wood, climate, & WK truck, and it is NOT a northern cold truck! 5 of the 6 cooling tubes in use today came off the original hopper @15000 miles. I never have cleaned them and they look pretty good. Tar is scarce around here, but I did get 3 quarts of tea from the first 140 miles this week. Here’s to tea, tar, testing, & trading ideas.

#24

Hi, Steve!

I am no administrator or rule setter, so what am I judging?
You speak from your sense of suitability, and good taste.

Max

#25

Thanks! Max
I did now go back and edit to remove all possible “you’s”, and all names except those of fellows I know personally with thick skins and short, tough toes.
S.U.

#26

Hi, Wes!

Yo! Its all good to dry the physical water out of the wood before the last stages of pyrolysis, so the unusable amount of water is not deteriorating the gasification processes.

The hot gases circulating from the hearth upward will pyrolyse the wood just above, and boil out water above that. The coarser the wood, the livelier the circulation. Tends to be up in the center and down at the outskits.

We know that hot (expanded) air is lighter than colder (compacted) air or gases.

Opening up a cooler return passage for the hot gases and steam in the silo will start a vivid circulation, IF there is equal or less resistance in the “return loop” than in the silo. (not good for deep cooling)

IF an internal cylindrical “negative chimney” has the same flow resistance as an outer cooler arrangement, the outer cooler will circulate the main part of the gases and steam. (Gas gets cooler; weighs more)

This means that if the outer cooler is made of equal thick material as the silo, the outer cooler will have a cooling benefit per weight unit!

Both systems can be used in parallel when maximum condensing effort is needed; as when the wood is too wet…

The main constructing point is that both systems shall have free unrestricted “access” to the silo, both in the upper and lower end.

…

Was about to forget your question of different metals as cooler material:

Iron-based metals have about 40000 times better internal heat transfere than the surface transition to and from gases!
So, it has no consequence if you use silver, copper, SS, or iron.
…

As to “ventilating” too much:

1937 it was tested in Germany with forced blower ventilation between the silo and an outer cooler. They could reach a point where the pyrolysing in the lower part begun to suffer, and the gasification process was deteriorating…

The risk to reach this point with natural “ventilation” is not overhelming (impending).

Efficiency:

Weighing the collected condens from wood with known
humidity (from same lot).

condense weight X 100
---------------------------- = drying %
wood weight

Max