Basics of burning Jatropha oil for lighting

Due to its physical properties, petroleum (parafin) burns in a different way. This has to be respected to find an appropriate way to use Jatropha oil for lighting.

The two pictures below show the principle difference of the burning process.
The pictures further below explain this proces in detail.

burning Petroleum	burning Jatropha oil
By the capillary effect the petroleum moves some cm upward in the wick. When lit, the flame heats up the petroleum. It evaporates and the vapor burns. The wick itself does not burn, it is only the transport device for the petroleum.	Due to its higher viscosity the capillary effect is smaller and the plant oil cannot be transported as high as the petroleum. Since it does not evaporate, it burns directly on the surface of the wick. The heat of the flame causes cracking of the oil molecules, so a deposit of carbon is developed. This has to be removed from time to time.

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The wick is placed into the oil.	The oil mounts in the wick by capillary forces. But much less higher than petroleum.	So the wick has to be short.	The flame should be near the surface of the oil to make sure that enough oil to be burnt is transported.	The oil burns at the surface of the wick. The wick itself burns too.	The high temperature of the flame causes some oil molecules to break. Carbon deposits are formed on the wick. After some time the capillarity forces are too small to transport the oil through the carbon deposit.	The carbon deposit has to be removed.	The wick is pulled up to replace the burnt material.

This priciples are respected in the design of this "Binga lamp". The floting disc, wrapped with aluminium paper, holds the wick in the centre and makes sure that the flame is only some mm above the surface of the oil. This lamp works for up to 8 hours without interruption. Afterwards the visible part of the wick is completely carbonised and has to be replaced.

last modification  08.10.01 by