Saturday, March 17, 2012

RUNNING AN ELECTRICAL GENERATOR WITHOUT FOSSIL FUEL


RUNNING AN ELECTRICAL GENERATOR WITHOUT FOSSIL FUEL




In Broad Outline
In order to achieve this objective, very much like, we need to feed the engine three things:
1. Air - this is fed in as normal through the existing air filter.
2. Hydroxy gas
3. A mist of very small water droplets, sometimes called "cold water  fog". Also, we need to make two adjustments to the engine:
1. The spark timing needs to be retarded by about eleven degrees.
2. If there is a "waste" spark, then that needs to be eliminated.
To summarise then, a good deal of work needs to be done to achieve this  effect:
1. An electrolyser needs to be built or bought, although the required  gas production rate is not particularly high.
2. A generator of cold water fog needs to be made or bought.
3. Pipes need to be installed to carry these two items into the engine.
4. The engine timing needs to be retarded.
5. Any waste spark needs to be suppressed.
6. Water tanks are needed for the cold water fog and to keep the  electrolyser topped up.
7. Ideally, some form of automatic water refill for  water tanks  should be provided so that the generator can
run for long periods unattended.

A Generalized overall sketch looks like this omitting the hydroxy gas, safety equipment, Electrical safety equipment, the starting battery and the automated water supply details:

The hydroxy gas is fed into the air system after the air filter, the  cold water fog comprised of a very large number of very tiny droplets, is also fed into this same area.

Creating the cold water fog
There are three different ways to generate the spray of very fine water  droplets which are a key feature of the success of this way of running the engine. One way is to use a Venturi tube, which, while it sounds like an impressive device, is actually very simple in construction:

It is just a pipe which tapers to a point and which has a very small nozzle. As the engine draws in the air/hydroxy mix on it's intake stroke, the mixture rushes past the nozzle of the Venturi tube. This creates an area of lower pressure outside the nozzle and causes water to exit through the nozzle in a spray of very fine droplets. Some perfume spray bottles use this method as it is both cheap and effective. An alternative method of making the cold water fog is to use one or more "pond foggers". These are small ultrasonic devices which are  maintained at the optimum operating depth in the water by a float. They  produce large amounts of cold water fog which can be fed into the  engine like this:



A third method is to use a small carburettor of the type used with  model aircraft. This does the same job as a regular engine carburettor, feeding a spray of tiny water droplets into the engine air intake. The physical arrangement of this option depends on the construction of the air filter of the generator being modified. with a lower grade of HHO which has some water vapour mixed in with it, it is possible to have a gas reservoir with pressure in it.

Some Safety Features
Up to this point, the electrolyser has been shown in bare outline. In  practice, it is essential that some safety features are incorporated as shown here:


The Reason for Changing the Timing
The fuels used with most internal combustion engines are either petrol (gasoline) or diesel. If you are not interested in chemistry, then you are probably not aware of the structure of these fuels. These fuels are called "hydrocarbons" because they are composed of hydrogen and carbon. Carbon has four bonds and so a carbon atom can link to four other atoms to form a molecule. Petrol is a long chain molecule with anything from seven to nine carbon atoms in a chain:

Diesel has the same structure but with eleven to eighteen carbon atoms in a chain. In a petrol engine, a fine spray of petrol is fed into each cylinder during the intake stroke. Ideally, the fuel should be in vapour form but this is not popular with the oil companies because doing that can give vehicle performances in the 100 to 300 mpg range and that would cut the profits from oil sales.  The petrol in the cylinder is compressed during the compression stroke and that reduces its volume and raises its temperature substantially. The air/fuel mix is then hit with a powerful spark and that provides enough energy to start a chemical reaction between the fuel and the  air. Because the hydrocarbon chain is such a large molecule, it takes a moment for that chain to break up before the individual atoms combine with the oxygen in the air. The main engine power is produced by the  hydrogen atoms combining with oxygen, as that reaction produces a large amount of heat. The carbon atoms are not particularly helpful, forming carbon deposits inside the engine, not to mention some carbon monoxide (CO) and some carbon dioxide (CO2) as well. The key factor here is the slight delay between the spark and the combustion of the fuel. The combustion needs to happen a few degrees after Top Dead  Centre when the piston is about to start its downward movement in the power stroke. Because of the delay caused by the hydrocarbon chain breaking down, the spark occurs a few degrees before Top Dead Centre:

If you were to replace the petrol vapour with hydroxy gas, then there would be a major problem. This is because hydroxy gas has very small molecule sizes which do not need any kind of breaking down and which  burn instantly with explosive force. The result would be an explosion which occurs far too soon and which opposes the movement of the rising piston as shown here:


The forces imposed on the piston's connecting rod would be so high that  it would be quite liable to break and cause additional engine damage. In the case of our electrical generator, we will not be feeding it a mix of air and hydroxy gas, but instead, a mix of air, hydroxy gas and cold water fog. This delays the combustion of the hydroxy gas by a small amount, but it is still important to have the spark occur after Top Dead Centre, so the ignition of the generator needs to be retarded by eleven degrees. Engine design varies considerably in ways which are not obvious to a  quick glance at the engine. The timing of the valves is a big factor here. In the smallest and cheapest engines, the engine design is simplified by not having the spark timing taken off the cam-shaft. Instead, production costs are cut by taking the spark timing off the output shaft. This produces a spark on every revolution of the engine. But, if it is a four-stroke engine, the spark should only occur on the power stroke which is every second revolution of the output shaft. If the fuel is petrol, then this does not matter as the extra spark will occur near the end of the exhaust stroke when only burnt gases are present in the cylinder. Some people are concerned when they  think of hydroxy gas burning and producing water inside the engine. They think of hydrogen embrittlement and rusting. However, because of  the nature of the hydrocarbon fuel already being used, the engine runs  primarily on hydrogen anyway and it always has produced water. The
water is in the form of very hot vapour or steam and the engine heat  dries it out when the engine is stopped. Hydrogen embrittlement does not occur as a result of using a hydroxy gas booster. Anyway, if we were to delay the spark until after Top Dead Centre as we must, then the situation is quite different as the waste spark will also be delayed by the same amount. With most engines, at this point in time the exhaust valve will have closed and the intake valve opened. Our very flammable gas mix will be being fed into the engine on it's intake  stroke. This means that our gas supply system is openly connected to the cylinder through the open intake valve, and so, the waste spark  would ignite our gas supply system (as far as the bubbler which would
smother the flashback). The situation is shown here:


we definitely do not want that to happen, so it is very important that we suppress that additional "waste" spark. So, this leaves us with two engine adjustments: timing delay and waste spark elimination. There are  various ways in which these can be done and as each engine design is  different, it is difficult to cover every possibility. However, there is a technique which can be used with many engines and which deals with both issues at the same time.Most engines of this type are four-stroke engines with intake and exhaust valves, perhaps something like this:


The intake valve (shown on the right in this illustration) is pushed  down by a cam shaft, compressing the spring and opening the inlet port. The exact arrangement will be different from one engine design to the next. What is fixed is the movement of the valve itself and that movement only takes place every second revolution. There are various ways of using those movement to eliminate the waste spark and retard the timing. If a switch were mounted so that it opens when the intake valve opens and closes when the intake valve closes, then the switch
closure shows when the piston starts upwards on its compression stroke  and a simple electronic circuit can then give an adjustable delay  before firing the coil which produces the spark. This, of course, involves disconnecting the original electrical circuit so that no waste  spark is generated. The current flowing through the switch contacts can be arranged to be so low that there will be no sparking at the contacts when the circuit is broken again. The switch positioning might be like this:


An alternative is to attach a strong permanent magnet to the rocker  arm, using epoxy resin, and then position a solid state "Hall-effect" sensor so that it triggers the delay before the spark is generated.
If the engine did not have a waste spark, then in theory, the timing  mechanism of the engine could be used to retard the spark. However, in practice, the timing mechanism is almost never capable of retarding the spark to the position that is needed for running without fossil fuel, and so, some kind of delay circuit will be needed anyway. The sort of delay circuit needed is called a "monostable" as it has only one stable state. A basic circuit of that type is:


We can use two of these circuits, the first to give the adjustable delay and the second to give a brief pulse to the ignition circuit to generate the spark:


Making the hydroxy gas When the generator is running, we have a ready supply of electrical  energy, coming from a piece of equipment which has been specifically designed to supply large quantities of electricity for any required application. We are not dealing with the spare capacity of some low-grade alternator in a car, but we have substantial electrical power available. An Electrolyser will be needed, and since there is a steady supply of electricity,there is no problem. It is unlikely that an excessive amount of power would be needed. Another convenient factor is that this is a stationary application, so the size and weight of the electrolyser is not at all important, and this gives us further flexibility in our choices of dimensions. As this is an application where it is highly likely that the  electrolyser will be operated for long periods unattended,an automated water supply system should be provided. The water pump itself can be an ordinary windscreen-washer pump, and we need some form of switch which operates on the electrolyte level inside the electrolyser. It is sufficient to sense the level in just one of  the cells inside the electrolyser as the water usage will be pretty much the same in every cell. If you make the electrolyser in a suitable size or shape, then a simple off-the-shelf miniature float switch can be used. If you prefer, an electronic level sensor can be operated, using two bolts through the side of the electrolyser as the level sensor. A suitable circuit for this simple switching task could be:


When the electrolyte level inside the electrolyser is in contact with  the upper bolt head, the circuit is switched off and the water pump is  powered down. The electrolyte has a low resistance to current flow, and so it connects the 4.7K resistor through to the base of the BC109 Darlington pair. This keeps the two transistors switched fully on which keeps the 8.2K resistor connection well below the 0.7 volts needed to switch the ZTX6533 transistor on. If  you are concerned about the ZTX6533 transistor being partially on, then resistor "R" could be added, although the prototype did not need one. The value would be about 2K. When the electrolyte level falls below the upper bolt head, the first two transistors switch off, and the ZTX6533 transistor is then powered fully on by the 4.7K resistor and the 8.2K resistor in series, providing the 150 mA needed for the relay to be switched fully on. The circuit draws about 5 mA in it's standby state. The numbers on the relay symbol correspond to the numbers on a typical automotive 12 volt relay. Using two BC109 transistors as the front end allows this circuit to be used with tap water if you wish. However, the water-level control for the water supply to the pond fogger or Venturi tube misting device does not need any form of fancy mechanism. The standard ballcock valve mechanism which is used with toilets is quite adequate, especially if a floating pond fogger is being used as it maintains its own optimum depth below the surface and so the overall depth is not in any way critical provided, of course, there is sufficient depth for the fogger to float correctly.

Starting:
When left for any length of time, the gas pressure inside the  electrolyser will drop because the nature of the hydroxy gas alters. This means that there will not be sufficient hydroxy gas available to start the engine and no more gas will be generated until the engine drives the generator. So, to deal with this situation, a lead-acid car
battery is included so that it can be switched in to replace the  generator for a brief period before the engine is started. That inclusion gives this overall arrangement:


This arrangement is perfectly capable of running a standard generator  without the use of any fossil fuel. It should be noted that while no fossil fuel needs to be bought to run this generator system, the electrical output is far from free and is actually quite expensive as there is the purchase cost of the generator, the electrolyser and the minor additional equipment. Also, generators have a definite working life and so will have to be refurbished or replaced. It might also be remarked that if a generator of this type is going to be used in an urban environment, then the addition of sound-reducing baffles and housing would be very desirable.

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2 comments:

  1. Hi. I'm having difficulty locating a source for the ZTX6533 transistor. Can you suggest either a source for it or a suitable substitution (a different transistor type)? thanks!

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  2. Also, what type of FET do you suggest for the spark-timing circuit?

    ReplyDelete