About: I like to design, construct and experiment with both old and new technology, especially when it includes mechatronics. I'm also devoted to photography, computers, programming and technology in general.

Background:

This is another thermoelectric experiment/ornament where the whole construction (candle, hot side, module and cool side) is rotating and both heating and cooling itself with a perfect balance between module output power, motor torque & rpm, candle efficiency, heat transfer, cooling efficiency, air flow and friction. A lot of physics are going on here but with a very simple construction. I hope you enjoy this project!

See videos for final result:

Youtube Video 1

Youtube Video 2

Youtube Video 3

Some other of my thermoelectric projects can be found here:

Thermoelectric Fan

Smarthphone Charger

Emergency LED





Concept:

The heart of the construction, the thermoelectric module, is also called a peltier element and when you use it as a generator it's called seebeck effect. It has one hot side and one cold. The module generates power to drive a motor which axis is attached to the base. Everything will turn and the air flow will cool the upper heat sink faster than the aluminium plate below. Higher temperature difference => increased output power => increased motor RPM => increased air flow => increased temperature difference but decreased candle power. As the candle also follows the rotation the heat will be less efficient with increased speed and this will balance the RPM to a nice slow rotation. It cannot go too fast to put out the fire itself and it can't stop until the candle runs out of fuel.

http://en.wikipedia.org/wiki/Thermoelectric_effect



Result:

My original plan was to have stationary candles (see video) but I found this construction was both more advanced and fun. You could run this with stationary candles but it will require 4 of them if you don't use two modules or larger aluminium heat area.

The speed is between 0.25 and 1 revolution per second. Not too slow and not too fast. It will never stop and the fire will burn until candle runs empty. The heat sink will be quite hot over time. I used a high temperature TEG module for this and I cannot promise a cheaper TEC (peltier module) will make it. Please be aware if temperature exceed the specification of the module it will be damaged! I don't know how to measure the temp but I cannot touch it with my fingers so I guess it´s somewhere between 50-100C (on the cold side).