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Questions tagged [thermoelectricity]

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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
75 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
46 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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19 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
35 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
65 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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18 views

Transferring heat from unit area to unit volume

I am trying to make a Peltier AC but before that I want to calculate how effective it will be. If I know the temperature t on the area A of the cold side of Peltier device. How can I calculate the ...
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13 views

Substitution of $-E_F-E_g$ for $E_F$ in distribution function and transport integrals for holes

As far as I understand, holes occupancy governed through distribution defined as follows, $h=1−f=1−\frac{1}{e^{\frac{E-E_F}{k_BT}}+1}$ but when I tried to calculate transport coefficient involving ...
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26 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
22 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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2answers
35 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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1answer
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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
64 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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23 views

Would thermophotovoltaic cells or thermionic converters be most effective for creating 5MWe from a nuclear reactor in space?

Assuming that the working coolant is a NaK and Li-7 mixture heated to 800 degrees Celsius, would a thermionic converter (as used in the SNAP-10A reactor) or a thermophotovoltaic cell1 serve as the ...
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2answers
195 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
20 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
36 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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133 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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1answer
79 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
44 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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2answers
56 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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2answers
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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
46 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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3answers
1k 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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1answer
93 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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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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2answers
51 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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1answer
104 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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1answer
177 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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19 views

Could hydrogen be generated on a typical house's roof?

If you stack normal solar cells on top of each other you're still using only 4% of the electromagnetic spectrum. The remainder is currently wasted as heat. What if you stack solar cells on top of a ...
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1answer
279 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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33 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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1answer
99 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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2answers
142 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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109 views

Are there mathematically rigorous textbooks on heat flow/heat transfer?

I have a fairly difficult problem involving conduction, convection, joule-heating and thomson effect, I am looking for a textbook that explores the mathematical formulation of heat flow problems and ...
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1answer
121 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....
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124 views

Why do electrons and holes carry heat in a Peltier element?

I have read quite a lot on Peltier elements but I still can't figure out why they work exactly. Consider the following (well-made) animated diagram of a Peltier element: I think the reason why ...
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4answers
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What do we mean when we say an electron collides with a molecule or atom?

When current flows through a conductor, it is said that the flowing electrons collide with the molecules or atoms of that conductor which causes resistance. The collision of electrons with molecules ...
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0answers
53 views

Inaccurate temperature from FLIR thermal camera

I am working on some problem where the knowledge of the temperature is required,so I am using the FLIR thermal camera to obtain temperature readings. However, when I look at planar objects which ...
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2answers
127 views

Coupling of two different metals

I have read about thermoelectric effects such as the Seebeck effect, the Peltier effect, and the Thomson effects. I understand that if there is a temperature difference between two ends of a metal, ...
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1answer
789 views

is there any relation between the emissivity and the temperature?

I was just wondering if there is any relation between the emissivity and the temperature (i.e. temperature as a function of the emissivity). If yes, can you write the relation and cite a reference ...
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2answers
430 views

Seebeck effect or Peltier effect for optimal thermoelectric effect?

I am building an experimental thermopile, and I'm getting confused with the definitions for the Seebeck effect and Pettier effects. From Wikipedia: The Seebeck effect: The Seebeck effect is the ...
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1answer
236 views

How does the Seebeck effect explain this thermocouple

I have just watched Copper Oxide Thermoelectric Generator, it's a short video (around two minutes) that purports to create a thermocouple from two wires of the same material. From Wikipedia: ...
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1answer
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What would be the nature of the plot of electrical conductivity of a metal with absolute temperature? [closed]

What should precisely be the equation of the curve of electrical conductivity of a metal and absolute temperature? Will the conductivity approach infinity at zero kelvin?
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1answer
38 views

Need some help understanding Peltier Plates

When shopping for peltier plates for a school project, I saw a seller that says that the plates are rated to 40 watts. I'm assuming this is talking about when they are used for cooling though, and not ...
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0answers
56 views

Is there a way to speed up Peltier cooling?

Speed up in sort of like, once you connect the powers, you don't have to wait long for the Peltier element to cool down to desired temperature. Is there a way to fix this, perhaps use two or three ...
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476 views

Seebeck effect and thermoelectric series

According to thermoelectric series of Seebeck effect the direction of current at hot junction is from metal occurring earlier in series to one occurring later. question is why they have used term at ...
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1answer
260 views

What does it mean by positive carriers (holes) carrying heat?

This is related to the Peltier effect. Using N-type semiconductor as a thermoelectric material, when a voltage is applied across it the majority charge carriers (electrons) move from the negative ...
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1answer
352 views

Why ZrO2 reservoir is useful for reducing tungsten's work function in Schottky field-emitters?

Schottky emitters (field-assisted thermionic emitters) use a tungsten filament for thermionic emission, as well as barrier lowering electric field to reduce the effective work function of the filament....