# Questions tagged [heat-conduction]

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12 views

### Source of light in a heating coil

When we connect a heater coil to an electric circuit then according to "joules law of heating effect" due to its resistance it will produce thermal energy . My question is why light is ...
23 views

### Quantum effects on phonon transport?

Phonons are the quanta of vibrations in a crystal lattice. As the name suggest, phonons are already a quantum phenomena but when studying heat transfer the phonons are mostly very classical (wave ...
40 views

### How to find external surface temperature with unknown heat transfer coefficient?

I am trying to calculate the thickness of insulation required for a certain design. The known properties are the inside temperature, target surface temperature and thermal conductivity. From what I ...
28 views

### Why water vapor condenses on glass? [closed]

I've read an answer to this question that stated glass was colder than air, causing this transfer of energy from the vapor to the glass, creating this condensation. But why is the glass colder than ...
28 views

### Understanding steady state in heat transfer on a molecular level

I am trying to get to a molecular understanding of what happens before a steady state is achieved. I understand that macroscopically, the temperature of any point along the rod won't change when ...
16 views

### Why is the tar condensing inside the Wood Pyrolysis retort?

I am facing some issues in wood pyrolysis. Doing in a 100 ltr drum. A lot of bamboo is not turning into proper charcoal. The tar is condensing inside the pyrolysis drum. It may be one of the reasons ...
42 views

### Why is heat current same in two different materials connected to each other?

I recently learned in my physics class that the heat current at a boundary between two materials with different thermal conductivities is equal. Why is this so? When these two materials are not ...
1 vote
152 views

### Why is heat current constant in a cylinder?

In a hollow cylinder made of some uniform material with thermal conductivity k, length L and inner radius a and outer radius b, the total heat current (dQ/dt) has a constant value in the direction of ...
14 views

### Understanding thermal models of cavitation

Cavitation is a phenomena that occurs in liquids when the local static pressure drops below the vapor pressure; bubbles form within the liquid. I am studying cavitation in incompressible, two-phase (...
1 vote
36 views

### How can I model convection in a simple and effective way?

I have a project in which we're trying to model heating of a room. We are modelling the room in 3D. The room has realistic walls, windows and a door, which will loose heat through them. To balance the ...
42 views

### Water heating up as it flows through a perfectly insulated pipe

I'm trying to solve the following problem: We want to know what the outflow temperature of the water, $\rm T_{water, out}$ is as a function of time. Knowing: Water is flowing through a thick pipe in ...
20 views

### Steady State Temperature Profile of a Centrally Heated Pipe (or rod)

This question is inspired by a question from 'Robomaze'. The OP now seems to have lost interest in it but I still think it's an interesting issue. I've cleaned up the original question and made it ...
71 views

### Thermal Conductivity and Specific Heat Capacity: Calculating the Time Required for a Volume of Water to Cool

I'm a chemist by training and have experience solving differential equations, though it has been insufficient in solving the problem I have. Here is the problem: I brew my own beer and I'm building a ...
40 views

### Is the gradient of temperature zero in case of steady state and no source of heat?

$$k \frac{dT^2}{d^2 x} +heat generation =\rho c \frac{dT} {dt}$$ In steady state and in the absence of heat source, the equation becomes: $$k \frac{dT^2}{d^2 x} =\ 0$$ If the laplacian of ...
27 views

### Types of heat transfer

I’m having some problems to identify the type of heat transfer involved in a practical experiment I’ve carried out. In my experiment, I heat a metal rod by making water vapor flow inside the rod, then ...
19 views

### Gas to solid heating?

I am doing a study on the phenomenon of pyrolysis. This is purely a study of the underlying physics. Generally, in practice, pyrolysis feedstock is heated conductively but we are examining the energy ...
67 views

### What does divergence of heat flux mean?

Before stating my question I will start with two definitions: Heat flux also named as thermal flux, is referred to as heat flux density, heat-flow density is a flow of energy per unit of area per ...
51 views

### Is the heat flow $\dot{Q}$ in a series system is same for all its constituent parts? Question is wrong

Question is wrong. You can close it. Actually I was learning about the conduction method of heat transfer. I found that there is thermal resistance for a system which can either be series or parallel. ...
1 vote
28 views

### Do inviscid fluids have thermal conductivity?

Inviscid fluids are an idealization and they don't have viscosity. The no-slip boundary condition DOESN'T apply to them and consequently, these fluids won't display a hydrodynamic boundary layer. I've ...
45 views

### Confusion regarding effects of changing any mass in Principle of Equilibrium of Mixtures/Principle of Calorimetry

My book says that a calorimeter is made of thin copper sheets, and the thinner the better since less mass means less heat capacity, which means for the same temperature change, less heat is required ...
28 views

### Why is all heat released by a deflagration wave conducted upstream?

I'm having some trouble understanding the phenomenological analysis used to calculate the thickness of a 1D deflagration wave (Combustion Theory by Williams, page 135). I quote the text below: ...
1 vote
102 views

### How does boiling work?

Let's assume that the exact boiling point of water is 100 degrees. Now I have a stovetop and a pot. I add the water to the pot, put it on the stovetop and turn the temperature to exactly 100 degrees. ...
38 views

### Is everything in nature a source of heat? [closed]

A source of heat is something from which heat is originated or obtained, whereas heat is the energy transferred due to temperature difference so heat is relative as the temperature difference is. Thus,...
41 views

### Questions about some analogies between heat and Shroedinger equations

Let $Z(x,t)=(4\pi t)^{-1/2}e^{-x^2/(4t)}$ and $G(x,t)=(4\pi t)^{-1/2}e^{-x^2/(4it)}$ be fundamental solutions of the heat $u_t=u_{xx}$ and Shroedinger $iu_t=u_{xx}$ equations. Function $Z(x,t)$ ...
42 views

### Trouble with deriving Fourier Number in Unsteady Heat Conduction analysis

Consider a metal ball being heated in a furnace. Thermal energy is convected to the ball while simultaneously getting conducted within. The Fourier Number, in unsteady heat conduction analysis like ...
1 vote
100 views

### In case of heat transfer in a rod, why actually steady state occurs after a time (why sections of rod cant further absorb heat)?

In heat transfer across a rod, why actually steady state occur? why temperature of sections of rod don't further increase as heat is even flowing through them and as whole rod is of same material then ...
1 vote
102 views

### Why does the steady state exist In thermal conduction?

In thermal conduction,why doesn't transient state go on continuously,why does steady state exist?why after some considerable time A metal bar sttached to a sink and source comes to steady state where ...
13 views

### How to determine qualitatively the metallic/semimetallic conduction behaviour by comparing chemical potential and thermal energy?

Suppose a material has a semi-metallic dispersion and we want to study electronic transport with small applied electric and magnetic field. Let the chemical potential be positive-valued (i.e. the ...
113 views

### 1D Heat Equation with different materials

I'm trying to solve a 1D-Heat Equation with Finite Difference Method in python. The object I'm trying to depict has "Material A" with a high conductivity on the outside and a core of "...