Thermoelectric Fan Powered By A Candle Pdf 20
Robert Worthey
The lower heat sink (hot side) was cut and polished to get it nice looking. I kept 5mm of the fins to absorb the heat well when the light flame burns and increases distance to the surface. New dimensions are 78x63x15mm. 4 holes are drilled through the heat sink and threaded as M4. 4 bolts will hold the lower heat sink on top of a wooden platform. Bolts go through the platform from below, covered with aluminum pipes for a better looking design and are screwed into the heat sink. The distance between wood and heat sink is 35mm but I would make it 40-45mm as the flame almost touches the surface. You dont want that because it creates black soot. The lower heat sink gets really warm but at the same time it works as a cooler to not get TOO warm, that would melt the TEG-module.
Two springs attached to M3 bolts fixate the upper heat sink on the lower, with TEC-module and thermal paste in between. Both surfaces of the TEC are covered with a thin smooth layer of thermal paste. The springs adds pressure as well as isolate the heat to travel to the cold side. The upper heat sink could also be screwed into the lower heat sink but then you need isolated screws.
The TEC is directly attached/soldered to the motor and the motor is attached to the upper heat sink by another small piece of metal and a cable tie. The fan is attached to the motor with a small belt wheel and glue.
Result:
I think the hot aluminum part get to about 100-150 Celsius, I measured the temp with a grill thermometer covered in thermal paste but cant tell how accurate it was. I measured 0.4V and 0.25A with one candle and 0.67V and 0.54A with two. That results in 0.1W resp. 0.36W output power. The efficiency to produce electricity this way is not that impressive though. A candle produce about 25 Watts, that means 0.7% efficiency.. But who cares, everything this machine does will eventually end up in heat any way =) That is a bit interesting, you increase the room-heating speed (I think) but looses nothing..
It is a bit noisy to have running all the time. To find the optimal motor/fan => airflow/noise level will require some more experimenting.
Mod Proposals:
Yes you can! In fact, third party fire safety engineers have examined JOI and found it much safer than burning an open candle inside a home, and safe for use indoors when operating instructions are followed. So even though the JOI was designed and tested for outdoor use, we think it can be used anywhere.
Your candle has been burning abnormally and has activated the JOI Lamp's safety feature. Wait approx. 4-5 minutes until you hear an additional snap signalling a reset of the safety feature. Change the candle, clean any soot buildup, and relight according to instructions.
This article reports the thermoelectric-based solar energy harvesting. The effect of candle soot (CS) coating on solar energy harvesting potential of thermoelectric modules is studied. To compare the performance, uncoated/coated modules are exposed to solar radiations (through Fresnel lens) and the other side is kept at lower temperature using continuous water flow. Substantial enhancements in electrical outputs are observed due to CS coating on the upper surface of the thermoelectric module. The open-circuit voltage and short-circuit current across coated module improve more than six times in comparison to the uncoated module with maximum voltage and current reaching up to 1.5 V and 14 mA. Similarly, the generator can deliver a maximum power of 10 mW across a resistance of 50 Ω. Results indicate that the CS coating is an effective technique to improve the performance of thermoelectric materials for running sensors and other low-power electronic devices.
The relative amount of heat produced by a candle or a human body is irrelevent. The important question is whether the fan _removes_ as much heat from the body as the amount of heat _added_ to the body because the candle warms the air. The fan is used to remove heat from the TEC, so the fan is blowing air that is _warmer_ than room temperature.
From knowing the heat output of a candle, and the cooling of a small fan, by feel, I think it would work. If anyone can be bothered getting the figures for how fast a person sweats and the specific heat of evaporation or whatever, we could conclude this. I bet $5 it cools the user more than it heats him.
Those interested in exploring Seebeck effect further should check the superb historical overview => -self.com/MUSEUM/POWER/thermoelectric/thermoelectric.htm Scroll down to the marvellous 1959 Russian Kero lamp radio !
To generate electricity out of a candle flame, I decided not to go the obvious route of buying a TEG, but instead to try building its ancestor, the thermopile.
A TEG, or thermoelectric generator is a device made of a number of semiconductor junctions in series that generate a small voltage when a temperature difference is applied to them. They are essentially the same in construction as the more common TEC, or thermoelectric cooler, that can be found easily on ebay.
The main reason why I have decided not to use them, is that TECs/TEGs get damaged at temperatures above 150C or so. Since the flame of a candle is well above that temperature, I would need to come up with a way to reduce the flame temperature to a usable value.
A thermopile is a series arrangement of thermocouples. It works in the same way as a TEG, but uses metal junctions instead of semiconductor ones. Thus, it is more rugged and can easily withstand higher temperatures.
At first, I tried making a thermocouple out of materials I had at home, namely copper wire and nichrome wire, but the results were very poor, as I could only get a few millivolts out of it when exposed to a flame. So, I ordered a K thermocouple to cut its wires into pieces and experiment with thermopiles.
After the failed attempt, it was clear that to work well a thermopile requires the metal to be exposed to the flame. Having learned that, the next step was to make a working device and not just a test. I wanted to get around 200mV out of it (see the next part for the reason), so that means 6 thermocouples in series. After spending some time thinking how I could make a design with 6 thermocouples close together enough to be heated directly by a single candle flame, this is what came out. I used four mica spacers to prevent shorting, and epoxy on the outer spacers to provide some mechanical robustness to the design.
Actually a peltier element from a 12V car fridge works in reverse. Did an experiment once with a high power LED and four peltiers around a tea candle (heat sinks and a fan too) and got at least 20 times as much light as from the candle alone. Fridge peltier elements use a lower temp solder that TEC modules so 160 C is around maximum on the hot side. Building a DIY cell phone charger for camping or hipster meet ups, is very doable.
About the size of a small soup can, this power on demand thermoelectric system converts the heat of a single tea candle into an electrical current capable of providing bright indoor or outdoor light using its plug-in lamp attachment. It can also charge the batteries used in cell and smartphones through its battery charger attachment.
The compact, patent pending Tellurex tPOD1 (a trademarked acronym for thermoelectric Power On Demand) can provide up to four hours of continuous bright light from one five cent tea candle. With power generated by a candle, the tPOD1 system can also recharge a companion battery pack that, in turn, will provide adequate power for limited smartphone calls, emergency text messaging and GPS rescue signal use.
Effective first aid and food preparation while in isolation and awaiting rescue both require a good source of light. The benefits of GPS capabilities now part of many cell and smart phones require power. Battery powered devices will exhaust their power, often with no readily available means of recharging. The Tellurex tPOD1, which can address those needs with a candle, may become as important as flashlights, smoke detectors and fire extinguishers in domestic homes or workplaces.
The light, portable Tellurex electric generator system is rugged and has no moving parts. Its fuel source is readily available around the world and does not degrade during long-term storage. When lit and positioned below the generator, the tea candle is protected from wind, and the integrated generator and lamp may be moved and interchanged while it's operating. Weighing in at less than twelve ounces, the device fits easily into backpacks or auto glove boxes.
Tellurex Corporation is a Traverse City, Michigan-based, pioneering company in thermoelectric applications. The company develops its own products and also collaborates with others to advance thermoelectric technology into medical testing equipment, wireless sensors and a variety of applications in both power generation and thermal management.
Description: The candle-powered car is an application of the Seebeck Effect. This effect is the result of thermal energy conversion directly into electricity. This phenomenon can be used in elementary school to show energy conversion from heat to electricity to the kinetic energy of the car. A more detailed explanation will be required in high school related to electron response to temperature differences in different materials. The Seeback circuit used in this candle-powered car can also be connected to a voltmeter and used as a temperature sensing thermocouple.
A thermoelectric cooler works in reverse of a thermoelectric generator. When a voltage is applied to thermoelectric cooler, an electrical current is produced. This current induces the Peltier effect. With this effect, heat is moved from the cold side to the hot side. A thermoelectric cooler is also a solid-state semiconductor device. The components are the same as a thermoelectric generator but the design of the components in most cases differ.
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