The Compleat Distiller

THE COMPLEAT DISTILLER 49
Condensers
In Chapter 3, we discussed five important factors of condenser design. They are:
a. The area of the cooling surface. If you double the area, you double the heat transfer.
b. The thermal resistivity of the condenser material. Again, double this factor and halve the heat
transfer.
c. The thickness of the material separating the vapor from the coolant. If you double the thickness,
you halve the heat transfer.
d. Turbulence − the movement of both vapor and cooling medium relative to the cooling surface that
separates them.
e. Usually, you get the best efficiency when vapor and cooling medium run in opposite directions.
We also arrived at a Rule of Thumb:
1 kW of boiler power will raise the temperature of cooling water flowing at 1 liter per minute by
14ºC (26ºF)
The molecules of a gas are much further apart than in a liquid, making heat transfer less efficient. It is
possible to pass vapor through a tube or system of tubes and to cool those tubes with air, but it will be
difficult because both materials are gases, and have poor heat transfer characteristics. The design of
such a system will have to be quite clever. Car radiators work quite efficiently because the medium
being cooled is a liquid and is in intimate contact with the finned radiator tubing. And on that subject,
if you are contemplating using a car radiator as a condenser for your vapor - DON’T! Car radiators are
generally manufactured with lead solder, and if they have been used, are probably contaminated with
lead from the fuel. You don't want lead to get into your product, because you will be consuming it.
Lead is a very nasty and cumulative poison that builds up in the body.
These factors should be considered when you choose what type and size of condenser you want to
make. Since your requirements may be unique, and different from anyone else’s, any dimensions that
we give are only indicative. Feel free to change them slightly, as your purposes or materials require.
This is the Ideas Department, and the most important ideas are your own!
We discussed the various types of condenser in Chapter 3. Now - how can you make them yourself?
The Liebig Condenser
The familiar Liebig condenser has limited surface area, but very easy to make. You can
increase the condenser’s surface area by making it longer, or using finned tubing. Vapor
is usually passed through the central tube because this contains the vapor in the smallest
volume and surrounds it with cooling liquid. The Liebig condenser works most
efficiently when held at an angle with vapor flowing downwards.
You can easily make a simple and effective Liebig condenser by holding a central tube
inside a larger tube with corks. Two small holes need to be drilled through the corks or
the outer tube itself for the cooling water inlet and outlet tubes.
Fig. 4-3