Peltier thermopar for hand heat charging battery

[mitro]

Look it looks simple
What if decrease size of parallelepiped by increasing their number?

 

[berkeman]

What kind of battery are you wanting to charge? Trying to use energy from the heat of your hand will not yield you much for trying to charge a battery. It would be much more practical to use a hand-squeeze exerciser to drive an electric generator.

 

[mitro]

I think it thermopar provide enough power to turn on phone or smartwatch if reducing their consumption when dead battery.
I'm convinced that a peltier is necessary. Even if simply up battery capacity, device will still discharge itself, but less frequently.

 

[berkeman]

I think

Can you show us your calculations that support this? How much energy do you get out of a Peltier thermoelectric generator with a human hand as the heat source? How much energy does it take to recharge a cellphone, even with a long charge time of a few hours?

 

[mitro]

your calculations

Сreators of technology calculations better.

 

[berkeman]

Сreators of technology calculations better.

Sorry, that did not translate very well and I'm not able to parse it. Please try again with more words? Please show us your calculation so we don't waste time on a question that has an answer of "impossible". Thank you.

 

[OmCheeto]

This thread makes me want to break out my old timer resistors, and do the maths experiment, as I got out one of my TEC1-12706 peltier chips and verified that smooshing my fingers on it generated 0.1 volt.

ps. 99% sure, that this is a bad idea. But hey! Wrap yourself in a body sized peltier chip suit, and it might charge a AAA battery in a couple of months.

pps. понимаете

 

[mitro]

I wear a Casio 5230 with solar power watch, and it's been working for years.
The warmth of hand generates more energy than a light bulb.

 

[OmCheeto]

I wear a Casio 5230 with solar power watch, and it's been working for years.
The warmth of hand generates more energy than a light bulb.

According to the Casio 5230 User Guide, turning the light on for 4.5 minutes will drain the battery in your watch.

I did though do some more googling and found a young lady who invented a hand peltier powered flashlight, which could probably be modified to charge a battery.



I'm guessing she used a Joule Thief like circuit to boost the voltage, as 4 of my peltiers in series would only generate about 0.4 volts, and I believe white leds require at least 2.4 volts.

So I'm going to modify my answer to yes, this is possible, for incredibly low power/energy devices.

 

[mitro]

Is peltier still produced in its original form, invented in 1838?
There may be other material options or such as flexible semiconductors of n-type and p-type to to separate dual plate.

 

[russ_watters]

The warmth of hand generates more energy than a light bulb.

That isn't true. The entire body puts out about 70W of heat. The surface area of a hand is probably 1% of the entire body. And peltiers even with large temperature gradients are only a few percent efficiency. You'd be lucky to get a few miliwatts like this.

 

[AlexB23]

That isn't true. The entire body puts out about 70W of heat. The surface area of a hand is probably 1% of the entire body. And peltiers even with large temperature gradients are only a few percent efficiency. You'd be lucky to get a few miliwatts like this.

Yup, a student built a hand heat powered torch back in 2014, and the torch needed 6 mW to power. The torch lit up, but barely.

Smithsonian: In the spring of 2013, Makosinski submitted her patent-pending invention to the Google Science Fair, where she was awarded the top prize in the age 15-16 category and took home a $25,000 scholarship. But to commercialize her invention, she'll need to figure out a way to get it up to spec with others on the market, which have a brightness output ranging from 90 to 1,200 lumens; her version currently maxes out at 24.

Torch power:
https://www.smithsonianmag.com/inno...-powered-by-the-touch-of-your-hand-180950226/

 

[256bits]

The warmth of hand generates more energy than a light bulb.

The whole human body at normal rest/light activity generates around 100W of metabolic energy production. If all the energy production was to be lost through the skin ( discounting that lost through the act of breathing expelling air at body temperature ), the heat loss from a hand is
hand surface area - 10cm x 10 cm = .01 square meters ( palm of a hand )
body surface area - 2 square meters ( a large person )
Heat loss from hand = 100W x 0.01m² / 2m ==> 0.5 watt

@mitro Since it is your project, you can continue the calculation to show the efficiency of recovering that palm heat and turning it into volts and amps ( milliamps <-> microamps ) with a Peltier device operating under Seebeck principle, with a hot side of 373 K and the expected cooling temperature, ( somewhere .01 watt to 0.01 watt, or less ) and what type of device could be expected to operate.

PS @russ_watters beat me to it, while I was typing in.

 

[256bits]

Yup, a student built a hand heat powered torch back in 2014, and the torch needed 6 mW to power. The torch lit up, but barely.


Torch power:
https://www.smithsonianmag.com/inno...-powered-by-the-touch-of-your-hand-180950226/

And for how long would the 6mW last, as the tube would lose cooling as hand heat warms it up, and the device in turn lose electrical energy production. Still I have to give the girl credit. See post 9 for the video.

 

[AlexB23]

And for how long would the 6mW last, as the tube would lose cooling as hand heat warms it up, and the device in turn lose electrical energy production. Still I have to give the girl credit. See post 9 for the video.

No idea, as I am not an engineer. Probably figure out the conductivity and mass of the metal, then use Newton's Law of heating.

 

[256bits]

No idea, as I am not an engineer. Probably figure out the conductivity and mass of the metal, then use Newton's Law of heating.

I was speaking rhetorically, but nice answer.

 

[AlexB23]

I was speaking rhetorically, but nice answer.

Thank you. I cannot read people at all, cos of how my brain is wired. But thanks. :)

 

[russ_watters]

Yup, a student built a hand heat powered torch back in 2014, and the torch needed 6 mW to power. The torch lit up, but barely.

Torch power:
https://www.smithsonianmag.com/inno...-powered-by-the-touch-of-your-hand-180950226/

Good science fair project but I'm surprised they bothered to patent it.

 

[AlexB23]

Good science fair project but I'm surprised they bothered to patent it.

Yeah, I am surprised also. Probably for money grab or something. Also, thermoelectric tech is fascinating, cos spacecraft beyond Jupiter run on heat from radioactive isotopes. :) That's totally metal, pun intended.

 

[256bits]

Good science fair project but I'm surprised they bothered to patent it.

Just in case some materials are found to increase efficiency from the current Peltier device.

 

[AlexB23]

Well, a smart watch company made a thermocouple powered watch, but they are no longer around:
https://www.cnet.com/reviews/matrix-powerwatch-2-review/

 

[mitro]

Peltier a simple component maybe it can be is improved in institute conditions.

 

[sophiecentaur]

The whole human body at normal rest/light activity generates around 100W of metabolic energy production. If all the energy production was to be lost through the skin ( discounting that lost through the act of breathing expelling air at body temperature ), the heat loss from a hand is
hand surface area - 10cm x 10 cm = .01 square meters ( palm of a hand )
body surface area - 2 square meters ( a large person )
Heat loss from hand = 100W x 0.01m² / 2m ==> 0.5 watt

@mitro Since it is your project, you can continue the calculation to show the efficiency of recovering that palm heat and turning it into volts and amps ( milliamps <-> microamps ) with a Peltier device operating under Seebeck principle, with a hot side of 373 K and the expected cooling temperature, ( somewhere .01 watt to 0.01 watt, or less ) and what type of device could be expected to operate.

PS @russ_watters beat me to it, while I was typing in.

Something that has not really been stressed in this thread is that a thermoelectric generator needs both a Hot source and a Cold sink. The temperature difference would need to be maintained at a nearly constant value.

My evidence::
I used to have a Peltier driven fan to help circulate air from the top of my log burning stove, with a hot source of a bit over 100C and a heat sink of, say 200cmsqu it would drive a small motor enough to turn a fan. The heat sink temperature would have been between 50 and 60C (almost too hot to pick it up). That would imply a temperature difference of around 20C+ which was maintained by the running of the fan to cool it. The generator was producing enough power to work an LED (hardly a 'torch', worth using). I did improve on the fan I bought by using a bigger heat sink and better air flow - but marginally.

If you use an area of the body as a source of heat, it also needs a form of radiator / heat dissipator and the temperature difference between these two needs to be maintained. Your hot hand is just not enough for the proposed system. A Peltier panel would need to be against the skin and the heat radiator would need to be over the surface of the clothes and maintain a temperature near to ambient. The demonstration with the palm of the hand is just not realistic because you need your hand after a very short time. Maybe a radiative panel on the forehead would do but only when out of doors in cool weather.

I think you need to look at the 'silly' ads online, to find just-feasible systems for people who just like that kind of thing. But do we see that system used out in the street? A fun project which would be useful for getting a grasp of the practicality of this Energy Harvesting idea. A thermometer and a DMM would give anyone valuable experience of the sort of quantities that are involved.

Never say "never" but.

 

[mitro]

Something that has not really been stressed in this thread is that a thermoelectric generator needs both a Hot source and a Cold sink. The temperature difference would need to be maintained at a nearly constant value.

My evidence::
I used to have a Peltier driven fan to help circulate air from the top of my log burning stove, with a hot source of a bit over 100C and a heat sink of, say 200cmsqu it would drive a small motor enough to turn a fan. The heat sink temperature would have been between 50 and 60C (almost too hot to pick it up). That would imply a temperature difference of around 20C+ which was maintained by the running of the fan to cool it. The generator was producing enough power to work an LED (hardly a 'torch', worth using). I did improve on the fan I bought by using a bigger heat sink and better air flow - but marginally.

If you use an area of the body as a source of heat, it also needs a form of radiator / heat dissipator and the temperature difference between these two needs to be maintained. Your hot hand is just not enough for the proposed system. A Peltier panel would need to be against the skin and the heat radiator would need to be over the surface of the clothes and maintain a temperature near to ambient. The demonstration with the palm of the hand is just not realistic because you need your hand after a very short time. Maybe a radiative panel on the forehead would do but only when out of doors in cool weather.

I think you need to look at the 'silly' ads online, to find just-feasible systems for people who just like that kind of thing. But do we see that system used out in the street? A fun project which would be useful for getting a grasp of the practicality of this Energy Harvesting idea. A thermometer and a DMM would give anyone valuable experience of the sort of quantities that are involved.

Never say "never" but.

I do not understand you. Think If we want to cool computer chip, need to split thermopar into two parts with a flexible semiconductor. For example, apply cold part to the chip, hot part insert in laptop lid.

 

[DaveE]

https://www.coherent.com/materials/rare-metals/thermoelectrics

 

[mitro]

https://www.coherent.com/materials/rare-metals/thermoelectrics

This termogenerator it exists in initial version separately from consumer technology.

 

[sophiecentaur]

I do not understand you. Think If we want to cool computer chip, need to split thermopar into two parts with a flexible semiconductor. For example, apply cold part to the chip, hot part insert in laptop lid.

Could you explain how you think your idea of a cooling system would work - along with a diagram or a reference to one? Thank you.

 

[mitro]

Now idea is simple, perhaps it will turn out like this?
I have not seen any real examples of such devices.

 

[256bits]

Something that has not really been stressed in this thread is that a thermoelectric generator needs both a Hot source and a Cold sink.

That's where @mitro should come in to do at the very least the thermodynamic inferences, include a COP, and other aspects of his device. The 0.5 watt that I came up with is only the available low quality heat, and not the useful. The Carnot thermodynamic cycle says not all available heat can be recovered to do useful work.

PS: One could say that the 0.5 watt could be increased in cold weather as the ΔT would be greater, perhaps up to a temperature difference between 37 C body temperature ( skin temp is actually less in normal human operation ) and 0 C ambient, or greater still with an ambient -20 C cold winter air. Plunge a hand in ice water at 0 C., or go outside without gloves at -20 C and see the effect. The uncomfortable feeling, no matter what part of the skin to which the device is attached, is there. The body compensates for the over and above heat loss by such means as either restricting blood blow to the skin, lowering the skin temperature, or if in the case where the core body temperature sensors detect too much of a heat loss, by other means to increase metabolism such as shivering, or you do actively increase metabolism by muscle movement.
This is another aspect - the physiological conditions of such a device.

A possible design strategy:
Step 1 - determine amount of usable energy from energy harvesting on active animals ( human )
Step 2 - determine a secondary energy consuming device, or devices, where the usable energy could sustain operation.
Step 3 - determine wearability of the energy harvester device and the energy consuming device.
Step 4 - determine physiological effects upon the animal
Step 5 - go back and repeat Step 1, as many times as necessary to finetune

The steps would not be followed as a linear progression, and given here just serve as a model so as to come up with something that may be worthwhile to investigate. Such as what passive device ( RFID for example ) could be enhance with an internal power supply, in this OP, not with a battery, but with energy harvesting in the μW to mW range. Certainly not for laptop battery charging.

 

[256bits]

Now idea is simple, perhaps it will turn out like this?
I have not seen any real examples of such devices.

The extended 'Flexible Semiconductor' has electrical resistance, and thus I²R losses to be overcome, so could be a No-Go from that perspective. I can't say one way or the other since off hand I do not know. Maybe that is the reason the Peltier devices are thin compact sheets, or it could be something else.