OUR SAWMILL RUNS ON WOOD!
(Page 3 of 4)
November/December 1982
By the Mother Earth News editors
(The accompanying photographs show, in addition to the generator and the cooler/filter, two other pieces of equipment that we haven't yet described: a narrow tank wrapped with copper tubing and a PVC column with a sight glass. One of these is an air preheater and the other a supplemental moisture trap, and both—originally designed for our Chevrolet truck—are now being tested in conjunction with the stationary system. If they prove to be worthwhile, we'll detail them in a future update.)
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COOLANT CIRCULATION
In order to eliminate the need for auxiliary pumps or heat-dissipating storage tanks, we've used the engine's existing cooling system, coupled to an air-conditioning condenser, to provide the low temperatures required for the coolant to do its job.
The condenser—which, in this case, functions as an air-to-water heat exchanger—was mounted immediately in front of the engine's normal radiator, so air is drawn through both finned-tube devices by the fan. Coolant is extracted from the engine block's drain plug (which is under pressure at all times) and routed to the lower inlet of the extra radiator. After passing through that exchanger, it's directed to the inlet on the filter's cooling chamber, then returned through the central outlet to the suction side of the engine's water pump . . . which also serves as the heater return line.
This simple system has performed even beyond our expectations on the stationary unit (as well as on our Chevy truck), and has brought filtered gas temperatures down to below the 120°F mark at times.
WORKING IN THE REAL WORLD
Since the smoke generator/engine combination was installed, we've logged a total of about 50 hours of operation on the mill . . . trimming planks for our woodworking shop, cutting structural members for our cordwood barn, and simply demonstrating the setup to visitors. Though the powerplant does strain when running the saw through the largest timbers, it shows the same symptoms when burning gasoline, so we don't believe we've sacrificed much power by using wood gas. Startup time (the waiting period necessary to produce highquality fuel after firing the assembly) has been averaging about 13 minutes, and wood consumption (we use scavenged fist-sized chunks of pine 2 X 4's) works out to about one generator load—equivalent to three-quarters of a 55-gallon drum—every 4-1/4 hours . . . at our usual 3,000-RPM operating speed.
Should we ever have to duplicate the setup, the only changes we'd likely make would be in the drive, rather than the fuel, system. We used automotive components because they were on hand and thus didn't cost anything, but better performance could probably be obtained through the use of a step-down belt drive connected between the engine shaft and the saw's main shaft.
Right now, we're satisfied with the way the modified components have been working . . . though of course we're still keeping a constant watch on them. In an upcoming issue—after we've had a chance to fully evaluate our new carburetor—we'll report not only on that two-barrel dual-fuel delivery system, but on the four-barrel mixer we're currently using on our 454-cubic-inch truck engine.
