Generation of electricity from fire

Direct conversion

 

Principle

It has been suggested that the movement of ions in flames could be used with a magnetic field to make electricity.  I suggest, along similar lines, a different geometry.

Consider a cylindrical mass of burning gas.  Enclose this with a cylindrical coil carrying a heavy electrical current.  Inside this place another coil of a conductor so that this is between the flame and the magnet.

When the gas is hot there is a high content of ions that can carry a current of electricity. As this gas expands some of the magnetic flux is expelled from the gas and the change in magnetic flux in the inside coil will generate an electric current.

Simplify

The coil that makes the magnetic field can also sense the change caused by the expansion of the hot gas, thus only one coil is required.

Make an Oscillator

Put this coil into a tank circuit with a capacitor.  Charge the capacitor then connect to the coil, the current flow will compress the flame, making it hotter.  As a result it will oppose this compression and then the current decays and the gas will expand. As the gas expands it will do work on the magnetic field making a bigger charge accumulate on the capacitor than initially.

The cycle will then repeat and the amplitude of the oscillations will increase until losses prevent further increase.

Extract Power

Once this has happened the device may be used to deliver electrical power to another system by connecting the system as a parallel load.

In this diagram, it may be seen that the surface area of the plasma is much less than the surface area of the inside of the torus of windings that contain it.  Thus there will be a force toward the centre, which is constant along the radius but the area of a torus at a particular radius will decrease toward the circle of the centre.  Thus as the plasma contracts the pressure on it will increase. The area is 2(pi)rl, where l is the length of a line drawn round the circle of the torus of the plasma at the point.  So as the radius of the plasma decreases the pressure increases as 1/r.  Thus near the centre the pressure will increase very rapidly without any stress on the containing torus of windings.  This makes the achievement of very high pressure possible through moderate current in the windings.

Comment

If you look at the "Thermonuclear Power" section it may be seen that this may be used to extract power from the containment mentioned there.

Chris 17/2/2002.