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Open Source Roaster – Using Fibonacci sequence to match the perfect Coffee!

Open Source Roaster – Using Fibonacci sequence to match the perfect Coffee!


Open source, released from a OSHWA member, and focused on having the perfect coffee. Boom! It seems a joke, but it is one of the most serious projects I’ve seen so far.

From a physics expert, studying the science behind the roasting process and willing to improve it, providing a machine that can easily and economically assembled wherever in the World (while from the developing Countries, it is nearly impossible to import a commercial machine from USA or EU) and uses Fibonacci principles to have a perfect coffee bean.

You can contribute in many ways, as usual for open source projects, just contact the authors on the official page below.

The roaster design is based of the Fibonacci Sequence, which is a number sequence that makes a “Golden Spiral”. This sequence is found everywhere in nature from the spiraling of sea shells to the average length of your fingers in relation to your finger joints.

The Fibonacci on the roaster starts on the outer shell of the drum housing and continues into the drum and the placement of the stirrers inside the drum. This allows for a larger combustion chamber (as gas burns it expands). As it expands, the heat energy is pulled along with the gyroscopic momentum created by the rotation of the drum. At the closest point between the drum and outer shell, a space is allowed to compress the heat energy before it is pulled back through the flames. The theory is that this will help to create energy efficiency.

This theory is derived from two sources:

Charles Law

-Kinetic Theory of Gases

A separate ventilation system is added into the combustion chamber. There are several reasons for adding this unique feature: To keep combustion gases from mixing with the roasting vapors, to be able to control the temperature in the combustion chamber in relation to the corresponding stage of roasting, and to be able to control the amount of pressure inside of the combustion chamber.

4 probes (2 pressure and 2 temperature) are planned for installation to monitor the status of pressure and temperature in the expansion area as well as the compression area to test these theories.

Aside from the aforementioned probes, there will also be probes in the exhaust behind the drum, in the faceplate (one positioned to monitor bean core temperature and the other to measure atmospheric temperature inside the drum), one on the cyclone, and one before the cooling tray fan.

These will be used to monitor the different regions of the roaster to assemble data one the thermal absorption, loss, and flow dynamics of each batch.

An Arduino computer board is planned to monitor these activities, which will be sent to a laptop with a data-logger program. The Arduino is a great match with project as it is open source, powerful, and easily customizable.

Each probe readout will be compared on a graph (time to temperature). Once enough data has been collected the various roasts and profiles will be compared and analyzed, and the roast methods will be adapted.

Source: Open Source Roaster – Coffee Laboratory