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THE PERFECT ENGINE RUNS ON BIOMASS
The Miracle Biomass Engine
By Jack H. Bayless – Consultant
An adaptation of a rotary motor used several years ago by Germans in submarines during World War II, can be used as a heat engine to propel automobiles. This engine is described in US Patent No. 4,949,688 (lapsed). As shown in the Patent Figures, the engine is an opposed piston, rotary engine. The operation is described in detail in the patent and the action of the pistons is controlled by a slotted, angled drive shaft. This controlled action is in contrast to the earlier design of the engine, which consisted of a drive mechanism of gears and connecting rods. (See Popular Mechanics, June 1962)
The advantages of the angled piston drive mechanism include simplicity, very high displacement, high torque output, and ease of adaptation of various fuels as well as design for either internal, or external combustion chambers. The external combustion chambers could be high-pressure heat exchangers for use of any combustible fuels, including powdered wood products or other bio-mass. Powdered biomass may be used in either the internal combustion mode or in external combustion mode. Each of these variations is discussed below.
Simplicity
The drive mechanism of the engine consists of only three moving parts-the angled drive shaft and two connecting rods. This drive mechanism allows cyclic motion of two piston carriers, each of which has two opposing pistons. To minimize inertial effects, the pistons may be attached to the connecting rods with ball bearings in opposing raceways, to give a pendulum effect in a rotating force field. The rotation of the pistons may also serve as a flywheel. When contained in a toroidal chamber, the four pistons enclose four chambers which expand and contract as the pistons rotate in the toroidal chamber. The donut shaped chamber has an intake and exhaust port, which are open to the various chambers as they rotate past. Thus the engine duplicates the action of an eight cylinder automobile engine.
Displacement
An engine of this design with a 12 inch diameter toroidal chamber and 2.5 inch diameter pistons, has a displacement of a 200 hp automobile engine. This briefcase sized engine would only weigh 100 lbs, but deliver as much power as a 400 lb automobile engine. Structure of the case would be designed to hold the center together, but this may be augmented by a band with ball bearing races opposite races in the piston carriers for additional strength.
Torque
Casual examination of the opposed piston design makes one conclude that torque output would be very low. However, detailed examination of the geometry and physics of the engine show that the moment arm of the advancing set of the pistons at mid stoke is 5 inches compared to 2 inches for the trailing set of pistons. In addition, the connecting rods travel along an inclined plane, doubling the torque. Thus the torque output is 3 to 4 times that of a comparable V-8 automobile engine. The torque is so high that it would be possible to eliminate the automatic transmission of an automobile powered by this engine. This high torque may make it necessary to design starters that act on the piston carriers, rather than on a flywheel.
This design can be almost frictionless by mounting all moving parts on roller/ball bearings and with close tolerance fits, seals can be labyrinth seals such as in turbines, and in ground glass hypodermic syringe plungers and cylinders. Angled grooves in the piston wall may be an effective labyrinth seal for pistons also. The crankcase can be sealed and lubricated with dry film lubricant or powdered graphite, eliminating oil changes and resulting pollution.
Fuels/Combustion Chamber
This engine having a single combustion chamber, can be designed to run on gasoline, powdered bio-mass (cellulose or other combustible materials such as paper, straw, dried leaves, or wood). In order for powdered organic materials to burn, a high residence time, high temperature, high-pressure combustion chamber may be necessary. Other possible adaptations include an atmospheric pressure, external combustion chamber, where heat generated would be exchanged to high-pressure air in small tubes containing the pressurized air generated in the engine. Exhaust heat may be used to preheat combusion air or even compressed air that may be of lower temperature.
Alternatively, biomass may be broken down by high temperature into combustible gases and char. Char can be powdered more easily and added back to the combustible gases. This process may be accomplished by the exhaust heat of the engine.
Fuel Economy
As discussed below, excess air can be used to lower the explosion temperature to that of hydrocarbon fuels, which would also improve fuel economy. It is estimated that one pound of powdered biomass would propel a full sized car one mile. Thus a charge of 200 pounds would result in a range of 200 miles, less than gasoline, but more than batteries.
A large contribution to fuel economy is the fact that solid fuel is converted to gaseous products. Biomass is 60% bound water, which is converted to steam when burned. This insitu steam generation may contribute a 15% improvement in fuel economy.
The high temperature combustion chamber design could improve fuel economy, since conventional engines use a water jacket to cool the cylinder heads, thus losing about 25% of the heat generated. If necessary, the temperature in this combustion chamber could be controlled by injecting fuel into the intake port every other intake stroke, converting the engine into the equivalent of a V-4 engine. Titanium alloys which retain high strength up to 1500 degrees F, could be used for pistons and the high temperature combustion chamber. Alternatively, high pressure water injection could cool the pistons of the engine. The low RPM and long stroke inherent in the design of this engine would asssure complete combustion of any fuel used.
Near frictionless design of cylinders and pistons would improve fuel economy about 10 %. In addition, placement of the ports could retain some of the pressure normally lost to the exhaust, improving the fuel ecomomy an additional 10%. The lower weight and elimination of transmission losses would also improve fuel economy. None of these economies are possible in conventional V-8 engines or in a Wankel design.
Other fuel variations could include lean mixtures, stratified charges,etc. The heating value of biomass is much less than hydrocarbons, but these fuel economies could make up much of the difference. Also of interest is that biomass and carbonized biomass has a much higher flame temperature due to the fact that less air is required to burn it. This higher temperature may be reduced by using much more excess air than is required to burn it. Excess air could form an envelope around the fuel air mixture to minimize heat loss to cylinder walls and pistons. However, higher temperatures generally result in greater thermodynamic efficieny of heat engines. Alternatively, biomass and carbonized biomass could be injected as a slurry in water or vegetable oil to result in lower flame temperatures. This may improve fuel economy 10 to 20%.Of course the engine could run on conventional fuels such as gasoline and low octane hydrocarbons. To start the engine with biomass, a preheat with an large electric glow plug would be used. Also it would be practical to start and run the engine on gasoline and then switch to other fuels after warm up. For bursts of power, rich mixtures or liquid fuels could be injected.
The Diesel Cycle
This engine could be designed to use slurried biomass or carbonized biomass (charcoal) injected into the high temperature combustion chamber at lower than normal diesel compression ratios. The design could also include complete exhaust, by making the pistons come to almost complete closure. This option could also include preheat of the compressed air and/or slurried fuel by exhaust heat exchangers.
Conclusions
This is a miracle engine in that low weight, high torque, multi-fuel engine can be possible thus allowing much more flexibility than is realized with electric motors using hydrogen fuel cells, or batteries.
Since we will soon experience a shortage of fossil fuels, engines that can operate on renewable sources will be in great demand. It takes several years to develop new technology, so development of these engines should begin now.
Notes:
If the links below don't work you can copy and paste the internet address to see Patent and Explosion Pressures of Biomass.
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=4949688.PN.&OS=PN/4949688&RS=PN/4949688
If the link below doesn't work enter patent number in the search field.
Biomass is the Perfect Fuel since it adds no new carbon dioxide to the atmosphere, and it is the Perfect Storage medium for the Perfect Energy, solar, as it requires no expensive housing and it can be dried by solar energy.
Pressures generated by biomass explosions have been documented at:
http://www.warren-group.com/publications/articles/grain-dust-handling-part-i-explosion-hazards/index.cfm
Starting at atmospheric pressure. pressure generated by ignition in an engine can be estimated by multiplying by the compression ratio of the engine. Reaction rates and explosive limits would also be greater due to heat of compression and increased initial pressure. Most of the values in the table are for valuable agricultural products, but the use of waste agricultural products should be feasible, since the products are mostly cellulose and would combust in the same manner.
Abrasives (silica) can be minimized in the manufacturing of powdered biomass. Other solid residues after burning biomass should be expelled without any undue effects (much like lead oxides were before unleaded gas became widely available). Some diesel engines generate soot with no apparent problems. Even abrasives may not be a problem since the particle size will be less than the piston clearances in the engine. If solid residue becomes a problem, an exhaust cooler could be used to condense some of the water in the exhaust and the water used to collect the solids and be disposed of at the time new fuel is taken on. Alternatively, a pleated fiber-glass filter could be designed to take out the solid residue in the exhaust and be periodically disposed of.
Some of the concepts outlined above may be applicable to ordinary internal combustion engines. It is hoped that no patents be pursued since these concepts are now public domain by this publication.
If you want to find out more about biomass, search the internet with the word biomass.
If you would like to help create an interest in this effort-please copy and forward the address to your mail list. Also post the article to your web page or discussion group. Any contribution to establish a web page for this effort would be greatly appreciated. This could end US dependence on foreign oil. This project would also make an excellent effort for a mechanical engineering college department.
The Explosibility Index is included in the explosion hazard comparison of several agricultural dusts found in the table below. This table lists several common agricultural product dusts and gives a comparison of the hazards associated with each one.
Explosive Properties of Agricultural Dusts
Type of Dust(A) Ignition temperature of cloud degrees F(B) Minimum ignition energy joules(C) Minimum explosive concentration oz./cu. Ft.(D)Maximum explosion pressure, psig(E) Maximum rate of pressure rise, psi/sec(F)Relative explosion hazard(G)
(A)------------(B)-------(C)------(D)------(E)-------(F)------(G)
Alfalfa----------860------.320------.1------66-----1100----Weak
Cocoa---------788-------.1-------.045----65-----1200----Moderate
Corn-----------752------.040-----.045----95-----6000----Strong
Corn cob-----752------.040-----.030----110----5000----Severe
Cornstarch--716------.020-----.040----115----9000----Severe
Cotton linters-968----1920----.500 ----48-------150----Weak
Cottonseed---878-----.060----.050----104-----3000---Strong
Grain, mixed-806-----.030-----.055----115-----5500---Strong
Rice------------824-----.040-----.045------93-----3600---Strong
Sugar----------662-----.030-----.035------91-----5000---Severe
Tobacco------788 -----------------------------7-------200------- --
Wheat---------896------.060-----.055----103-----3600---Strong
Wheat Flour-716------.050-----.050------95-----3700---Strong
Source: Kennedy, Patrick M., and John Kennedy,
Explosion Investigation and Analysis, 1990.
Engine Patent
Biomass Explosions
Send E-Mail to: jbayless@pdq.net
Copyright © 2006 Jack Bayless. All Rights Reserved