Thermocouples, Voltage, and Circuits

[compsciguy]

Homework Statement

Hello all, I have a physics project that I am working on in which I have to develop a heat engine to do something useful. Rather than do the classic putt-putt-boat or candle-powered turbine (which have to be built from scratch), I thought I'd do something unique, and build a thermocouple.

However, I have run into a few problems.

First of all, a thermocouples voltage output is rather small (about 30 mV or less), and it's power output is minute (don't know what it is precisely though, just small). In order to run a very small LED light, I need around 2 amps of energy at around 2-3 volts.

Because of this, I run into problems... my thermocouple isn't powerful enough to run the lightbulb.

Even if I run it in array circuits (which adds up the voltage), it still is not very much power nor is it worth paying for.

Thus, I am looking for one of a few possible solutions
-Is there another low voltage device that does 'useful' work that I could power up that requires much less voltage and power that you know of?
-Is there a technique you know that will easily boost/store voltage so that way the lightbulb may be turned on periodically, if at all?
-If I was to use a battery or capacitor of some sort (which capacitors I don't think would work since they have a max voltage output depending on the device being used and aren't set by the capacitor), what would you suggest and how long would it take to charge up on the low energy of the thermocuple?
-Should I just switch to an easier heat engine?

Thanks in advance, and if this would be more appropriate in another section of the forums, please have it moved for me, thanks =).

Homework Equations

Thermocouple Metal Pairing with Sensitivity

Chromel/Constantan - 68
Iron/Constanta - ~52
Chromel/Alumel - 41
Copper/Constanta - ~43

These metals are all somewhat cheap, which is why I am using them over other metals.

Chromel is 90% Nickel, 10% Chrome. Alumel is 96% Nickel, 2% Manganese, 2% Aluminum. Constantan is 55% Copper, 45% Nickel.

I can use any possible circuit or storage type you can think of, although I would hope it wouldn't be too expensive.

I don't know of any other equations that would be useful... perhaps some electrical ones... but not sure.

The Attempt at a Solution

Haven't bought anything yet because of the likeliness of it not being able to work out. I've read a lot of information and looked at many of other people's attempts though.

The metals also have to be bought online (or I have to go out to a store very far away) so yah, it's better for me to plan through it first.

Thanks again for the help!

Best Wishes,
CompSciGuy

 

[KataKoniK]

Dear CompSciGuy,

I understand your frustration with your thermocouple project and the limitations you have encountered. It can be challenging to work with small voltage outputs and limited power sources, but I believe there are possible solutions to your problem.

One option would be to use a voltage booster or amplifier to increase the voltage output of your thermocouple. This can be achieved through the use of a transformer or a DC-DC converter. This would allow you to power devices that require higher voltages, such as your LED light.

Another option would be to use a thermoelectric generator (TEG) instead of a thermocouple. TEGs are designed specifically to generate electricity from heat differentials and can produce higher voltage outputs than thermocouples. They can also be easily connected in series to increase the voltage output.

If you do choose to stick with the thermocouple, I would suggest using a battery or capacitor to store the energy generated by the thermocouple. This would allow you to accumulate enough energy to power your LED light for a longer period of time. The charging time would depend on the capacity and efficiency of the battery or capacitor, but it should not take too long with a small power source like a thermocouple.

I would also recommend looking into more efficient metal pairings for your thermocouple. While the metals you have chosen may be inexpensive, they may not be the most efficient at converting heat into electricity. There are other metal combinations that have a higher sensitivity and can produce a larger voltage output.

I hope these suggestions help you in finding a solution for your project. It is always good to explore different options and try out different circuits and components to achieve your desired results. Good luck with your project!