KenC,

Thanks for your description of your drying fuel experiences.

It's my understanding that the hot exhaust does two things:

1. It provides the heat to drive the moisture out of the structure of the
wood
2. It provides a transport mechanism to carry the liberated water vapour out
of the drying vessel

To confirm the physics of this we need a chart showing the saturated gas
figures for nitrogen (or air) for temperatures from 100C to 700C, showing
the quantity of water which can be held in saturation for a specific volume
of the exhaust gas at certain temperatures.  The hotter the gas, the more
water can be held in saturation.

If the exhaust emerges from the manifold at 400C, and it is not saturated,
then it will remove moisture and cool to the point where it becomes fully
saturated and an equilibrium will be reached.

The saturated exhaust will then find its way out of the vessel, taking its
water load with it.

A new volume of non-saturated exhaust will be emitted from the engine to
replace it.

Over the course of time, the dividing boundry line between dry wood and wet
wood will move slowly away from the exhaust manifold and towards the exhaust
drying vessel outlet.

The drying vessel should be placed on a slope, so that condensed water
vapour on the cool vessel walls on startup has the opportunity to drain
away.



Ken B.

On 19 December 2010 07:28, Ken Calvert <[email protected]> wrote:

> Mark, sure you can  watch the condensation from an engine ticking over,
>  and which you have probably just started, but I challenge you to bore a
> hole in the floor of your car and point a IR beam thermometer down on the
> exhaust pipe when you are doing  >80mph.   You wouldn't be worrying about
>  relative humidity then.
> Its apples with apples, not  iceblocks out of the frig!
> Ken C.
>
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