The final component of the roasting machine...
And in an instant, this newsletter series on the important parts of the roasting machine comes to an end with a brief discussion on the exhaust fan.
The exhaust fan performs a number of different roles:
1. Changing fan speed alters the rate of convective heat transfer to the beans and also changes the proportion of bean heating resulting from convection versus conduction;
2. The fan removes smoke from the roasting chamber - a little smoke in your coffee can be fun, a lot of smoke not so much;
3. Finally the fan drives the vortex separation of chaff from the exhaust air flow.
The exhaust fan is a simple but crucial part of the roasting machine.