Questions tagged [thermoelectricity]

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Do thermoelectric generators use up heat to generate electricity?

When heat is transferred from the hot side to the cold side, electricity is generated. Does this mean that we're extracting energy from molecule vibrations (lower overall temperature) or from just ...
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48 views

Using heat to lift a liquid – What's a good way of turning heat energy to gravitational potential energy?

Edit: A bit of context... Living in a country with extreme heat and a lot of hills, many farmers need irrigation pump systems (pump up water from a pond up to a reservoir). I have for example seen ...
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60 views

How to prove that $\vec{E}$ is an intensive property?

In my homework I had a question to sort a few variables into intensive properties and extensive properties. I wrote that $\vec{E}$ (electric field) is an extensive property, thinking of a situation ...
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How can you create electricity from nano-scale heat flux?

This article "Engineers develop chip that converts wasted heat to usable energy" on the Science Daily website states the following claim: ...findings were published in the paper, A Near-Field ...
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53 views

Can a Peltier/Seebeck cell transfer energy from a “thermally insulated” system converting (a part of) thermal energy into electrical energy?

Suppose you have a closed system, as per the schema attached below, which walls are thermally insulated. Suppose you want to reduce the temperature of the fluid inside the closed system, without ...
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32 views

How big of a temperature difference is needed to power a thermoelectric generator?

I'm really curious about this and haven't been able to find a formula to calculate the types of voltages I could generate based on differences in temperature. An example of interest is The PowerPot ...
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31 views

Clarification on the three omega method for measuring thermal conductivity

I've recently come across the $3\omega$-method for measuring thermal conductivity in materials. Now I'm told that we use a lock-in amplifier to measure the 3rd harmonic in the voltage across the metal ...
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42 views

Why the Seebeck coefficient of platinum/palladium/tungsten changes sign when temperature rises from 0 K?

From Wiki and this paper: Cusack, N.; Kendall, P. (1958). "The Absolute Scale of Thermoelectric Power at High Temperature". Proceedings of the Physical Society. 72 (5): 898. What mechanism is related ...
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25 views

Will stacking 2 peltier coolers on top of each other reach a lower temperature quicker?

I'm working on a project where I'm trying to get freezing (<0 degrees Celsius) temperature as quickly as possible. Clearly, stacking 2 peltier coolers on top of each other will be less efficient ...
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1answer
142 views

Charge carriers type: contradiction between Hall effect and Seebeck effect, how to resolve it?

On one hand the Hall effect consists of a voltage that arises when an electric field and a perpendicular magnetic field are in a material. This makes the charge carriers (electrons or holes) under the ...
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29 views

How to reduce wasted heat in systems

How we can reduce the waste heat from systems such as car exhaust systems or large power plants and/or use it to enhance product performance ? Edit: let’s focus on one system for example a cars ...
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1answer
95 views

Which explanation of the Seebeck effect is correct?

I have just begun reading about thermoelectricity. However I’ve been struggling to find a satisfying explanation for the the thermoelectric effects, specifically the Seebeck and Peltier effect, The ...
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119 views

Physics mystery : why does it rotate?

In the beginning this thing was floating still and the candle was out. Then someone lit the candle and the flame somehow Made the object spin on the water. See the picture. I know a little bit about ...
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88 views

How much electricity might be expected from simply sinking a 20 foot copper rod or wire vertically into the ground?

Obviously I'm asking about the Seebeck effect. Assume steel wire for either end. And the East of England for climate (so likely temperature ranges top & bottom of the thing). Would something ...
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39 views

Thermo-electric current in the p-type semiconductor

I came across this picture : Source:thermo-electric generators Basically, within the p-type semiconductor, I don't know how holes move from the hot side to the cold one. How does this happen? If ...
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55 views

Are the thermoelectric effects reversible?

On the one hand, it is commonly said that thermoelectric effects are reversible. For Wikipedia they are thermodynamically reversible because as the factor of merit ZT approaches infinity, the ...
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1k views

Good conductor of electricity and bad conductor of heat

I wonder, how a graphite can be a good conductor of electricity but at the same time, be a bad conductor of heat.?! As we know, a body conducting electrons are bound to produce heat by resistance, ...
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3answers
61 views

Dependency of temperature acquired by a resistor on power

A nichrome heating element across 230V supply consumes 1.5kW of power and heats up to 750*C. A tungsten bulb across the same supply operates at a much higher temperature of 1600*C in order to emit ...
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1answer
103 views

Do electrons really diffuse when a temperature gradient is applied?

In many websites and books, it is generally said that the charge carriers, be it electrons or holes, diffuse through the considered material when a temperature gradient is applied. However I have ...
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1answer
63 views

Charge distribution in a heated metal (Seebeck effect)

Consider the Seebeck effect taking place in a single metallic rod, where one end is kept at $T_0$ and the other end at $T_0+\Delta T$. The charge distribution will not be homogeneous: the electrons ...
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28 views

Is the Thomson effect always associated to the Seebeck effect?

Since both the Seebeck and the Thomson effects involve a temperature difference in a material, assuming there is also a current through the material so as to activate the Thomson effect, shouldn't the ...
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1answer
45 views

Is it possible to generate conditions such that the temperature difference created by current is high enough to sustain it?

We know that current can generate temperature difference and vice-versa. But is it possible to generate such conditions that the temperature difference created by current is high enough to sustain it?...
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1answer
89 views

Thermoelectric voltage over a solder joint of two identic copper wires

My background: I'm engineer of electronic HW engineering and embedded computer systems. During repair of a vintage digital voltmeter (resulution 1µV) I discovered an effect that probably only a ...
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29 views

Can electric energy be generated from only heat if the heat is uniformly distributed along the system? [duplicate]

I was thinking about producing energy from heat and I realized that all the methods I know require a heat gradient. Is there a deeper physical explanation as to why heat gradients are needed? ...
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1answer
43 views

How is the relation for variation of resistivity with temperature obtained?

The graph of resistivity vs temperature shows a fairly straight line plot over a long range of temperature. Now, let us plot resistivity in the y-axis and temperature in the x-axis. Now, in my book ...
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73 views

Direction of temperature gradient while studying thermo electric effects

What is the direction of temperature gradient, when we study about thermoelectric power. And what is exactly meant by up and down the thermal gradient?
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Why do we have to compute maximum safe current through resistor equalizing heat exerted by the resistor and heat created in resistor?

My book says says resistance of a wire = $\rho l/\pi r^2$ where $\rho $= resistivity of the resistor material. l=length of the resistor. R= radius of the resistor so heat produced H = $I^2 \rho l $/ $...
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Which materials abosrbs heat? And which are good in practical applications

I want to design a component which cools the water in the absence of ice cubes,fridge etc.. Like water heater which works by electric supply.. Similarly water cooler which is independent of ...
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1answer
217 views

Seebeck effect and the need for two conductors

The Seebeck effect is really interesting and the reasoning behind the phenomenon does seem to make sense, that is, that electrons move from the hotter areas to the colder areas. What I don't ...
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2answers
871 views

How exactly does the Peltier effect work?

I'm having some trouble finding details on just how the Peltier effect (also known as the Peltier-Seebeck effect or the thermoelectric effect) works on a physical level. Am I correct in thinking that ...
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1answer
25 views

Is there Seebeck effect on junction between same metal but with different isotopes?

I recently discovered Mössbauer spectroscopy and its explanation drove me to think we should observe the Seebeck effect between two similar metals but with different isotopes. The main reason that ...
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1answer
40 views

How does a positive temperature coefficient thermistor work? (in terms of charge carriers)

I was wondering how a positive temperature coefficient (PTC) thermistor works in terms of charge carriers.
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267 views

Why do some materials have negative Seebeck coefficients?

I was looking in particular at Constantan with platinum when I was wondering how could something have a negative Seebeck coefficient. I presumed that it must be linked to hole movement throughout the ...
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145 views

Seebeck Coefficient. Microscopic understanding of seebeck effect

For the thermoelectric effect, now, consider the case of uniform voltage (uniform chemical potential) with a temperature gradient. In this case, at the hotter side of the material there is more ...
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1answer
72 views

Seebeck effect and potential difference

In seebeck whether electron moving from hotter to colder region creates potential or the heat itself cause atoms to be charged at an end? If without potential can a electron move from hot to cold end?...
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179 views

Understanding Joule heating

I’ve started my college classes, and I hadn’t cleared up something I wasn’t understanding. Under the conditions of current=voltage/resistance and heat generated by current=I^2*R, what confuses me is ...
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85 views

Why does changing the size of a hot junction not affect the voltage output of a thermocouple?

I am thinking of the thermocouple as just two wires twisted together and the twisted section being heated (hot junction). If one of the wires has a larger amount of the wire heated, but the same ...
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1answer
78 views

What will happen if I exceed the documented temperature gradient on my thermoelectric generator?

For fun, I am designing a electrical generator powered from natural gas. I have ordered 20 count of these devices: https://www.ebay.co.uk/itm/Thermoelectric-Power-Generator-Peltier-Module-TEG-...
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3k views

How much electrical power is needed to melt a wire? [closed]

I saw a video in which someone melted a metal wire with electricity. How much electrical power would this take?
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251 views

How to maximize Peltier devices' cooling capacity?

I am currently working on a project requiring the use of Peltier devices. I have attached the cool side of the device to a copper plate and the hot side to a heat sink with a fan. What would be the ...
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106 views

Thermoelectric diffusion equation

The speed of diffusion of uncharged point-like particles from one volume with concentration $n_1$ to another with concentration $n_2$ after removing the wall between them depends on $n_1 - n_2$ by $\...
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250 views

What causes the peltier effect between 2 metals?

In the Peltier effect, current through a 2-metal junction will cause an increase or decrease in temperature as electrons traveling through 1 metal are higher in energy than metals in the other level, ...
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103 views

Do you need an anode for a hot cathode (thermionic emission)?

I need an electron gun for a project that I'm doing. Is it enough to merely send current through a filament in order to shoot our electrons (using thermionic emission) or must there be an anode ...
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164 views

Thermonic Electron Gun

On the first figure, you can see schematic diagram of typical thermionic electron gun from Wiki.with filament voltage(1-2) electrons are emitted and with bias(1-3) - focused. and here is filament ...
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357 views

Heat loss in a cylinder (e.g. electrical wire)

Conceptionally there are things I'm not sure of in heat transfer, which I hope you can help me with. Say for instance we have a long electrical wire with a uniform temperature distribution (higher ...
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526 views

Stacking thermoelectric generators for a better efficiency

As far as I know, a thermoelectric generator has about 5-8% of efficiency. That means it uses 5% of the heat and converts them to electricity. Rest 95% is dissipated through the other side. So I can ...
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80 views

What are the efficiency limits of the Peltier effect?

I understand that thermoelectric coolers are perhaps a quarter as efficient as heat pumps. Why? What is the source of this efficiency limit? What would have to change for thermoelectric coolers to be ...
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131 views

Heat produced by a conductor

I recently got to know about how the heat produced in a conductor. It's due to collision of electrons when drifting due to electric voltage But my question is Why doesn't a non current carrying ...
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271 views

Relation between Seebeck coefficient and electrical resistivity?

I was wondering if there is a mathematical relation between the Seebeck coefficient of a material and its electrical resistivity (or conductance). For me it makes sense intuitively since (as far as I ...
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238 views

What is the energy output of Solar thermal collector?

I have a solar thermal collector. Its LCD screen shows an output of about 5KWH at the end of the day. How to interpret this number? Is this electrical KW (kilo watt)? If yes, isn't too low for a 1....