Opmmur
Time Travel Professor
Entirely Powered By Heat Of Human Hand
2 July, 2013
MessageToEagle.com - "My objective in my project was to create a flashlight that runs solely on the heat of the human hand," says Ann Makosinski, from British Columbia, who has succeeded with her invention.
Makosinski, a 15-year old tenth grade student at St. Michaels University School in Victoria, was among of thousands of ambitious kids from more than 100 countries participating in Google Science Fair project.
"If I can capture enough heat from a human hand and convert it efficiently to electricity," she hypothesized, "then I can power a flashlight without any batteries or kinetic energy."
Makosinski's Hollow Thermoelectric Flashlight is entirely powered by heat of human hand.
"Using four Peltier tiles and the temperature difference between the palm of the hand and ambient air, I designed a flashlight that provides bright light without batteries or moving parts," Makosinski said.
"My design is ergonomic, thermodynamically efficient, and only needs a five degree temperature difference to work and produce up to 5.4 mW at 5 foot candles of brightness."
In order to create the flashlight, Makosinski measured how much electricity could be generated from the heat of a palm — about 57 milliwatts — and how much she needed to light the LED — about half a milliwatt.
She decided to use Peltier tiles.
"If one side of these tiles is heated, and the other is cooled, electricity is produced. For my flashlight, I would be heating one side with the palm, and cooling the other side of the tile with a heat sink.
I calculated that our bodies radiate 5.7 mW/cm2, but only 0.5 mW is needed to generate a bright light at the LED.
Both produced power, but only a few millivolts. I need 2.5 V ! I had to convert my DC input to AC, and then run it through a oscillator circuit with a stepup transformer. My final circuit had only 4 parts and produced a step up ratio of 100:1. So for 50 mV DC from the Peltiers I obtained 5 Volts AC which was sufficient to light the LED.
The Hollow Thermoelectric Flashlight
The final design included mounting the Peltiers on a hollow aluminum tube which was inserted in a larger PVC pipe with an opening that allowed ambient air to cool the tube. The palm wrapped around a cutout in the PVC pipe and warmed the tiles. The result was a bright light at 5 degree Celcius of Peltier differential."
A 15-Year-Old Girl Creates Hollow Thermoelectric Flashlight - Entirely Powered By Heat Of Human Hand - MessageToEagle.com
The flashlight worked!
I'm really interested in harvesting surplus energy, energy that surrounds but we never really use. This took quite awhile 'cause I had to do it during the school year as well and I had homework, plays, whatever that I was also doing," she said.
The results proved Makosinski' hypothesis, that even with all the thermal and voltage conversion losses, there was still enough power in the palm to provide usable light.
Two flashlights that she has created do not use any batteries, toxic chemicals, or kinetic energy. They do not create any noise or vibrations and will always work.
The flashlight’s only limitation is its need for at least a 5°C temperature difference to provide usable light.
