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Even the most efficient thermocouples produce minute amounts of electrical energy. However, if put into series as a thermopile they can generate more electrical energy. What I wanted to know is are there theoretical limits to how many thermocouples can be put in series? If one could, hypothetically, create a great column of thermocouples hooked in series could it generate a more substantial amount of energy? Or are there other forces that would come into play as the series gets larger?
Or are there other forces that would come into play as the series gets larger?
Those 2 links don't tell me anything I don't already know if you read my original question. I've read wikipedia, I'm not an idiot, or too lazy to do my own research.What I can't find are physical limits. Would thousands or tens of thousands of thermocouples in series work, or does it create some resistive force that generates too much of it's own heat to properly allow temperature flow to work. No one is doing it...creating very large thermocouple arrays, I was wondering why. I know enough about Thermoelectric effects, I'm not looking for an education in that area.
There are clearly theoretical limits to the number of thermocouples you can hook in series. For example, if you got enough of them together they would collapse into a black hole.Similarly, if you only have this planet's resources to work with then there's a limit to what you can do. Eventually a stack of thermocouples might run into problems of electrical breakdown of the insulation, but that's probably not a practical consideration either.On the other hand, if there had been a practical limit then it's possible that I might have mentioned it, rather than pointing out that stacks of a large number of thermo-junctions are already widely available (and, of course, you can hook them in series too).It's true that the thermocouple has electrical resistance and this reduces the efficiency of the system but, if it turns out to be a problem you can connect them is series/ parallel arrays (or, as is equivalent) you can use bigger junctions made from thicker wire or whatever.Adding a buffer amplifier just means you need another power supply; not very helpful in this case.
The thermoelectric generatorWhile the Seebeck voltage is very small (in the order of 10-70µV/°C), if the circuit's electrical resistance is low (thick, short wires), then large currents are possible (e.g. many amperes). An efficiency trade-off of electrical resistance (as small as possible) and thermal resistance (as large as possible) between the junctions is the major issue. Generally, electrical and thermal resistances trend together with different materials. The output voltage can be increased by wiring as a thermopile.The thermoelectric generator has found its best-known application as the power source in some spacecraft. A radioactive material, such as plutonium, generates heat and cooling is provided by heat radiation into space. Such an atomic power source can reliably provide many tens of watts of power for years. The fact that atomic generators are highly radioactive prevents their wider application.
Thanks for that link. I hadn't seen that paper before.My thoughts are purely blue-sky wonderings right now. I was fascinated by the idea of generating power from temperature differences and was exploring ways to create a constant temperature difference. Most literature on the effect marginalizes the benefit because of it's poor efficiency (5% to 10% is what I read) and it's very low output. But what intrigues me is the output is additive in series, and there doesn't seem to be a limit to the number in series. In programming we do a lot of things where a very small effect, done a tremendous number of times, has a perceived big effect. So my thinking was, so what if it's not efficient and has small output, put a lot of them together to boost the output, and the ability to harness temperature differences with no additional energy means it could have a net positive output. So, blue-sky thought, what if you had a long pipe buried underground, the temperature on the outside of the pipe would be fairly constant. If done in arctic or volcanic areas you would even have a more extreme temp to work with. Then if you pumped water through the pipe at a different, controllable temperature, you would have a relatively cheap way to have a constant temperature differential. If that water was the runoff from some plant that super-heated it...even better.Now, if the pipe was double hulled with a layer of thermocouples, hundreds of thousands of them in series, or mixed series/parallel inside the layer. They could tap into that temp differential. If the differential is small, say just 30 degrees C and the voltage for a thermocouple is micro or milli volts, would it matter if there were a massive number of them in play? It would still add up wouldn't it? Anyway, thank you for indulging me my questions. I'm just curious about things and like to explore ideas.