Questions tagged [thermal-conductivity]

The thermal conductivity of a material is a measure of its ability to conduct heat.

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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 ...
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How best to maintain the temperature of a swim spa?

All the advice I have seen on the internet suggests that it is more economical to keep the thermostat of a hot-tub at its intended temperature, rather than turning down the thermostat when the tub is ...
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Why do most metals have high thermal expansion coefficient although their thermal conductivity are generaly high?

the relationship between thermal conductivity and thermal expansion in metals. Why do most metals have high thermal expansion coefficient although their thermal conductivity are generaly high? Please ...
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How to add markers to IR photographs

I'm using an IR camera to identify thermal patterns. The thermal images are similar to this [LINK] image. I'd like to add markers to the area being measured to determine dimensions and normalize the ...
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EM energy flux and heat distribution in a cylindrical conductor

Consider a cylindrical conductor made of a single material (say, copper) with conductivity $\sigma$. Assume there is a current through the conductor and, to avoid complications, assume that the ...
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Is higher or lower specific heat better for cooling an object via contact?

Suppose you want to cool an object by putting it into contact with another object, much colder object, and the transferal of joules to an intermediary equilibrium temperature is instantaneous. If this ...
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Why don't we overheat just by existing? What is the theoretical model? [closed]

Our bodies constantly generate heat, but we don't overheat just by sitting in room temperature! Why? Something about the shape of our bodies at standard-temperature-pressure is at equilibrium with the ...
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Does specific heat capacity depend on temperature of the substance?

A substance at 200-degree Celsius is given some amount of heat to raise its temperature by one degree Celsius and the same substance when at -200 degrees Celsius is given some amount of heat to ...
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What is the relation between phonon anharmonicity and thermal conductivity?

The textbook says that: if the vibration of the lattice were harmonic, then the states of phonons would be orthogonal to each other. As a result, there would be no interaction between phonons, hence ...
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Heat conduction across 2 solids with large thermal condcutivity difference

I am solving a transient heat condcution problem involving 2 solids using implicit finite difference method. At the interface, I soppose the finite difference equation at the interface should be $$ \...
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Clarification on Searle's method to determine thermal conductivity

Here In Searle's method to determine the thermal conductivity of a good conductor, the heat transfer rate of the conductor along a displacement(thickness) d is given by: Q1/t=KD(T1-T2)/d. =>Q1=KD(...
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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 ...
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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 ...
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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 ...
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Identical atoms in a potential energy well given heat

When two neutral atoms in the potential energy well are given some amount of heat, why does the distance between them tend to increase? It seems to me from the potential energy versus distance graph ...
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How to calculate heat dissipation of metal box? [closed]

Lets say I have a steel cubical box of size $1$m filled with water at room ($20$°C) temperature. At first everything in box is $20$°C temperature, and then internal water heater (with power of $10$kW) ...
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How long does it take specific types of metal to heat up in the sun?

I'm wondering how long it would take different metals -- for the sake of this question I'll say steel -- to heat up in the sun. Assume it was an 80 degree day and a piece of steel was sitting in a ...
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Defining Temperature [duplicate]

I have learnt the definition of Temperature as Temperature is defined as the average of Kinetic energy of the particles in the Object. My doubt is can't we measure the temperature near the sun as ...
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What would provide greater thermal insulation, a single 1.5 inch thick wool sweater, or 5 thin 0.3inch sweaters layered over each other?

So in this hypothetical,its winter time and your wearing lets say a shirt and a jacket, but inbetween the shirt and jacket you have the option of a sweater. But which layout would result in greater ...
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Adiabatic Index ($C_{p}/C_{v}$) Through Phase Change

Does the adiabatic index change when a phase change happens? For example, when we have a compressible liquid (say CO$_{2}$) inside a pipe that goes from high pressure (100 bar) to low pressure (1 bar) ...
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Thermoelectric Thomson effect as generator

In thomson effect we need an electrical current and a temperature difference at the same time. So it is possible use Thomson effect to generate an electric current? That is, how I generete an electric ...
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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 ...
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Time to heat an object

If I have a sphere of material (radius $= r$ and Temperature $= T_1$) in a hot environment $(T_h)$, how long will it take to heat the object to $T_2$, (where $T_1<T_2<T_h$) through to the centre?...
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Will stainless steel heat up faster than a cordierite-based surface in a gas oven?

Background: As some may know, pizza stones, used to accumulate heat before the pizza dough is put into the oven, are often made of cordierite. If it's well heated it should provide the underside of ...
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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 ...
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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. ...
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Why is my max heat transfer lower than the actual heat transfer value (NTU-method)? Heat exchanger effectiveness is greater than 1 [closed]

I am using the NTU-method to calculate the effectiveness of a heat exchanger. The fluids are water (cold) and ethylene (hot). So far I got: $$ C_h = c_{p,h} \cdot m_h = 42.9\frac{kJ}{kgK} \cdot 44.4\...
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Prigogine vs. Bronsted and the minimum entropy production principle

I apologize for the length of this question. Prigogine's minimum entropy production principle fails in the simplest heat conduction case, because the temperature distribution that minimizes the ...
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How to derive specific heat of a crystalline material from phonon density of states?

I have done a simulation of a crystalline material using DFT and have extracted its normal modes and its phonon density of states. Does anyone have an algorithm/code or a detailed resource that can ...
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Thermal boundary layer of an inviscid fluid

We know that an inviscid fluid flowing along a flat plate doesn't develop a hydrodynamic boundary layer because there is no friction. we also know that viscosity is caused by intermolecular forces and ...
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Thermal mass flow meter

I am trying to build a thermal mass flowmeter, but I am facing some challenges describing it theoretically. I have an aluminium pipe with a heating element. I am measuring the temperatures of the pipe ...
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Doubt regarding thermal conduction in series combination

How is the rate of heat flow same in both conductors when the thermal conductivity constant is different for both conductors?I have seen this everywhere and have been confused regarding this
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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 ...
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Why is cup containing coffee hot?

It happened that I was having my coffee and saw this video at the same time. It's an interview given by RP.Feynamn. In that Feynman explains about why is a cup containing coffee hot, he says that as ...
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Speed of heat through an object

According to the Heat equation (the PDE), heat can travel infinitely fast, which doesn't seem right to me. So I was wondering, at what speed does heat actually propogate through an object? For example,...
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Is thermal conductivity additive?

Suppose I have water in a beaker. I measured, its thermal conductivity by some means to be $\kappa_0$. Next, I added some salt to it so that it dissociate from it. Say, $$AB\rightarrow A^++B^-$$ Now, ...
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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 ...
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Possibility of combining photovoltaics and solar thermal energy

In a private setting, photovoltaics and solar thermal energy are often harvested on the home's roof and roof area is limited. So, I thought about combining both, i.e. mounting solar collectors ...
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Help regarding discovery question in Thermodynamics

new to the forum and I'm currently learning about "heat capacity" in my physics book, and I've had a bit of a tough time trying to see the reasoning behind a certain question. In this book, ...
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Drude theory for liquids

Suppose a compound AB that dissociates into A$^+$ and B$^-$ when dissolve into water. If we suppose that the Drude theory is valid with the same assumptions. Then we can write the conductivity as $$\...
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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 ...
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Does rate of latent heat transfer of steam to another fluid increase with increasing temperature?

I know rate of sensible heat transfer is dependent on temperature difference, but I haven't found much information on the rate of latent heat transfer of steam with respect to temperature. Take, for ...
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With what speed does a thermal front travel through a solid?

The heat equation provides theoretical temperature distributions as a function of space and time. Take for example an infinitely long rod that is suddenly heated up at $t = 0$ at its end $x = 0$. The ...
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4 answers
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Does anything in an incandescent bulb actually reach its color temperature (say 2700 K)?

This question is inspired by a question about oven lightbulbs over on the DIY stack. It spawned a lengthy comment discussion about whether an incandescent lightbulb with a color temperature of 2500 K ...
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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 "...
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Does boundary layers between two metals decrease thermal transfer rate?

Assuming perfect contact, does layering different metals decrease thermal transfer rate? I initially thought that since the two metals were in perfect contact, then the boundary between the two metals ...
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Heat transfer from stovetop through heated water to air [closed]

This is a question about efficiency. My understanding is that resistive heating is very efficient. So if I turn on an electric burner on the stove, once the stove+stovetop equalizes, radiation into ...
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Is there a name for the type of boundary condition where the initial boundary values are known but are not held constant over time?

I'm exploring the heat equation to model a particular 1D scenario, and I understood the Dirichlet and Neumann boundary conditions, but neither are sufficient for my scenario. Assuming a rod of length ...
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How do we justify the equation of heat current through a perpendicular cross section?

Fourier's equation for heat flow: $$ \frac{dQ}{dt} =-KA\frac{dT}{dx} $$ is usually derived by quoting its similarity with electric current and comparing variables to arrive at a similar equation. ...
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1 answer
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How can you determine how fast (m/s) heat will travel through a material being heated on one end?

I was wondering how fast heat will travel through rectangular glass bottle, heated on a tray under vacuum. I work in a lab where an inert atmosphere glovebox is used, and when moving glass bottles ...
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