Questions tagged [heat-conduction]

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Equation for simultaneous cooling and conduction

Imagine a long, uniform metal rod placed on the positive $x$-axis being heated with a power $P$ from its end at $x=0$. It is cylindrical in shape and the cross-section is a circle of radius $r$. ...
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264 views

How is the 1D transient heat conduction equation derived? [closed]

From my book: $$\frac{\partial T}{\partial t}=\alpha\frac{\partial^2 T}{\partial^2 t}$$ with an initial condition and boundary conditions $$T(x,0)=T_0$$ $$T(L,t)=T_0$$ $$-k\left.\frac{\...
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31 views

From Boltzmann transport equation to fouriers law - infinite speed of propagation of information

The macroscopic Fourier's law can be derived from the Boltzmann transport equation using the relaxation time approximation for the collision integral. This is demonstrated for an ideal gas in this ...
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A problem in heat conduction at a steady state

Question : Three rods of identical cross-sectional area and made from the same metal form the sides of an isosceles triangle $\triangle ABC$, right angled at $B$. The points $A$ and $B$ are ...
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1answer
107 views

Conductive heat transfer water through concrete to water

So I've been asked to do a calculation on heat loss from a floating swimming pool. Strange and not something you're likely to come across on an everyday basis. I have already calculated the ...
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15 views

Dependence of heat transfer rate on acoustic boundary layer thickness

I have generated a sine wave acoustic signal of constant amplitude and different frequency (i.e. 50Hz to 250Hz). At low frequency i am getting higher evaporation rate. However, at low frequency ...
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2answers
170 views

Should I walk or run to my towel when naked and wet? [closed]

This morning when I got out of the shower, I realised I had left my towel in the bedroom. Naked and wet I ran as fast as I could to get the towel. On my way back I didn't run, but rather walked, and ...
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4answers
256 views

What is heat and heat transfer?

Physics books write that heat is the transfer of thermal energy. They also write that heat transfer is the transfer of thermal energy from a thermodynamic system of high temperature to a one of lower ...
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1answer
98 views

Why no heat is absorbed by the conductor in steady state

Why is it that no heat flowing through the conductor is absorbed by any cross section when the conductor is in a steady state , there was a question on PSE about the same concept , but the answers ...
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2answers
194 views

What boundary conditions does a steady state initial temperature profile that evolves according to the heat flow equation obey?

A cylindrical rod of length $L$ is insulated over its curved surface. The end of the rod at $x = 0$ is in contact with a heat bath at temperature $\Theta_0$ and the end of the rod at $x = L$ is in ...
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1answer
295 views

How to develop a model for cooling rate of steel tube in air?

I am trying to develop an equation to determine the cooling rate of a steel tube in air. I'm using Fourier's Law, Stefan-Boltzman Law, Newton's Law as well as the specific heat capacity equation. The ...
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95 views

Heat equation volume source vs. heat flux boundary condition

I want to solve the heat equation in the 3D unit sphere $B$ with a general heat flux boundary condition, no volume sources and some given constant initial temperature: $$ \rho c_p\partial_t T - \...
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4answers
393 views

Why is a temperature gradient set up in a heated rod? [duplicate]

Suppose a cylindrical rod is maintained at 100 degree Celsius and the other at 0 degree Celsius. My book says that after reaching "Steady State" the rod will have developed a constant temperature ...
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775 views

Physical meaning of potential in heat equation

I'm working on the mathematical theory of parabolic equations. The prototype of such equations is heat equation given as follows : Let $\Omega$ be a bounded region of the space and $T>0$ a fixed ...
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2answers
61 views

Which heat equation should I choose if I want to toggle between conductive and convective heat transfer?

I have a science project where I have an aluminum cylinder, filled with oil, with a diode chain floating inside of it. The diode chain has a bimetallic temperature switch on it that turns off the ...
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3answers
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Why does a lot of water vapour come suddenly after the heat source of boiling water is removed? [duplicate]

I have noticed this several times. When I am boiling water, a few seconds before its boiling point, vapours are formed as usual. But if I turn the gas off before boiling, the moment it turns off, I ...
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2answers
204 views

More efficient way to heat liquids

If we consider two processes to heat up a bucket of water as follows:- Taking one bucket and heating it to our desired temperature for V volume. Taking two buckets of half the volume and heating one ...
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2answers
1k views

What is temperature as a function of time in Fourier's Law?

Can we find temperature as a function of time using Fourier's Law of thermal conduction? For example: If we have two square parallel plates of a given length, width, and distance apart with one ...
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3answers
119 views

Focusing Sunlight with Flat Mirrors- solar barbecue

Say somebody had 48 1sqft glass mirrors (almost 4.5 sq.m total), because these tiles cost about $1 each. If mirrors are all tediously aligned to redirect sunlight onto a Weber BBQ, the air temp inside ...
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2answers
2k views

Temperature at different points in a metal rod during heat conduction

$$ k = \frac{\frac{Q}{t}}{A(\frac{T_1 - T_2}{L})} $$ where k is thermal conductivity of the solid, Q is total amount of heat transferred, t is time taken for the heat transfer, A is area of the cross ...
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Behaviour of photons in different materials

Often when learning about heat transfer within metals and thermal conductors,the heat transfer is explained by saying how molecules vibrate in thier positions to conduct heat. But if that's the case ...
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1answer
103 views

Is the randomized motion of particles produce heat?

In the show on factomania from gregg foot I've heard that when sun light comes then some gas particles of air get more energy and velocity and as the average kinetic energy of molecules is Temperature ...
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1answer
74 views

Effect of pressure when drying wet clothes in a windy environment

When we hang wet clothes outside, they dry faster if it is windy. The wind causes forced convection and removes the air saturated with vapor, and the rate of evaporation does not decrease much in ...
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1answer
99 views

What causes burns when in contact with hot water?

As I understand it thermal energy (heat) is simply a measure of the kinetic energy of an object (For example : water).Hot water is simply water with a larger kinetic energy in its molecules, right ? ...
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3answers
431 views

In an adiabatic process, why is it that if work is done very quickly then there is no time for energy transfer to the surrounding?

I don't seem to understand the logic in adiabatic process of how 'if work is done on the system very quickly e.g. compress a piston containing n number of gas particles, there is no time for energy to ...
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1answer
897 views

Temperature of solids and “average translational kinetic energy”

Temperature is related to the random motion of atoms and molecules in a substance. More, specifically, temperature is proportional to the average "translational" kinetic energy of molecular motion. ...
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Thermic isolation for 3D printer buildplate

I have questions about heat conduction, directly related to a problem I have with my 3D printer. Here is (schematic) front view of my 3D printer buildplate: The orange top plate is a PCB heated bed (...
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43 views

Heat loss due to thermal penetration [closed]

I am doing an experiment on a regenerator (Period 120 s). I found the thermal penetration depth through the insulation as 13 mm. I'm not sure how to estimate this heat loss?. I tried to estimate by ...
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130 views

What is the physical limit of thermal insulation?

If we consider a container (at very low) temperature $T_0$ surrounded by some passive structure, in turn surrounded by an environment at temperature $T_1>T_0$, there will be an inward heat flow ...

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