Thermal conductivity Definition and 185 Threads

First off, for my EE100 class I chose to replicate the industrial electrical blankets that are out there. With that being said, I do own one and can tell that there are some kind of conductive, insulated wires (copper?) that run throughout the blanket which generate the heat. And of course, the...

Two metal rods, one silver and the other gold, are attached to each other. The free end of the silver rod is connected to a steam chamber, with a temperature of 100oC, and the free end of gold rod to a ice water bath, with a temp of 00 C. The rods are 5.0 cm long and have a square cross-section...

whats the thermal conductivity for car insulation? roof or dashboard, basically the thermal conductivity of foam used in most cars.

Let's say you have a small metal case that is 3 inches by 3 inches versus 2 inches by 2 inches. Inside at center is a heat generating source (let's say a small processor chip). How efficient is the transfer of heat from the processor to the air... and from air to metal between the 2 different...

Homework Statement Hot magma (1500 K) is flowing into the Earth at rates of 0.05 meters/year, 0.5 meters per years and 1 meter per year. Although more total volume of magma will retain a temperature at or above 1150 K at higher rates of flow for any given time (say, at 1000 years), a higher...

Homework Statement Rods of copper, brass and steel are welded together to form a Y-shaped figure. The cross-sectional area of each rod is 2.0 cm2 . The free end of the copper rod is maintained at 100◦C, and the free ends of the brass and steel rods at 0 ◦C. Assume there is no heat loss from the...

So, there's a project I'm working on (no, it's not school related), where I'm trying to figure out how to measure thermal conductivity of a material using laminar flow. The idea is to integrate this into a larger system, and it's a measurement I'd like to take in the process. I know the...

Ok, I've built a numerical model to show the cooling of hot magma sills entered into the crust over time. The results show that the volume of the "hot" zone when the emplacement of a constant volume of hot sills is all done will vary as a matter of two things: the overall rate at which the magma...

I was wondering if anyone knows the relationship with temperature and frequency tuning in wide bandgap semiconductors. I just want to know why wider bandgaps have higher temperature tolerance and why does that mean high frequencies can be achieved? Explanation with formulas would be great!

Since the flow of heat in solids happens due to the collision of the molecules with each other, thereby increasing their internal energy, a higher denser material will have molecules closer, does it mean that the thermal conductivity of high density materials will be higher than the lower...

When in a room a fridge is kept in such a manner that room is closed and door of fridge is on. Fridge is connected to supply what will be the effect on the room temp and why. The percentage in change of temp??

Homework Statement Three building materials, plasterboard [k = 0.30 J/(s m Co)], brick [k = 0.60 J/(s m Co)], and wood [k = 0.10 J/(s m Co)], are sandwiched together (as I've tried to show below). The temperatures at the inside and outside surfaces are 28.9°C and 0°C, respectively. Each...

Using kinetic theory, we can derive an expression for the thermal conductivity of a gas to be κ=nCmoleculeλ<v>/3 where n is the number density of the molecules in the gas, Cmolecule is the heat capacity of a single molcule (i.e the heat that must be given to each molecule to raise the...

1) PROBLEM: Task is to find the thermal conductivity of steel experimentally. I have conducted relevant experiments and I am trying to solve for the thermal conductivity (k) itself. My final however is ten times too large in size, and I am having trouble identifying where the error is coming...

Homework Statement The temperature within the Earth's crust increases about 1.0 C∘ for each 30 m of depth. The thermal conductivity of the crust is 0.80 W/C∘⋅m. A)Determine the heat transferred from the interior to the surface for the entire Earth in 9.0h . B)Compare this heat to the amount of...

The thermal conductivity of most solids and liquids decreases with increasing temperature, but water is an anomaly because it actually increases with increasing temperature. I don't understand why though. I suppose it is something about the material itself and its hydrogen bonding, but not sure...

The information I am given is : a door has two steel layers both are .47 mm thick, the door itself is 725 mm by 1800mm. The question asks, how thick of a layer of wood (oak) would have to be put in the door to limit the heat loss to 740kJ per hour? Temp inside is 18C and outside is -20C All...

Homework Statement One end of an insulated metal rod is maintained at 100∘C and the other end is maintained at 0.00 ∘C by an ice–water mixture. The rod has a length of 60.0cm and a cross-sectional area of 1.40cm2 . The heat conducted by the rod melts a mass of 7.15g of ice in a time of 15.0min...

Homework Statement Determine the thermal conductivity of a metal (assume linear heat distribution at steady-state, and well insulated), given, Thot = 96.8 Tcold = 29.5 There is also: 13.7 W being pumped in at one end. Water convecting heat away on the other end. Homework Equations...

Hi everyone, i am trying to solve and program a non linear differential equation in MATLAB where thermal conductivity depends on temparature.I am trying it to solve by explicit finite difference method. the given equation is ∂2t/∂x2+∂2t/∂y2 *k(t)= -q (x,y) i have solved the equation taking...

Homework Statement If a copper kettle has a base of thickness 2.0mm and an area 3.0 x 10-2 m2 estimate the steady difference in temperature between the inner and outer surface of the base which must be maintained to enable enough heat too pass through so that the temperature of 1 kg of...

Hello. In CGS unit electron thermal conductivity for plasma is expressed as \frac{n_{e}T_{e}}{m_{e}\upsilon_{e}}\Gamma_{1} [1] where \Gamma_{1} is the dimensionless transport coefficient. [2] You can also find similar expression in...

Homework Statement Part (a): Derive Clausius-Clapeyron Equation. Find latent heat of fusion of ice. Part (b): Find rate of formation of ice Part (c): What is the maximum thickness of ice formed? Homework Equations The Attempt at a Solution Part (a) I have derived the...

Homework Statement Given an insulating case outer surface at 25C, radiates heat to surroundings at 20C. Find temperature inner surface. Homework Equations The Attempt at a Solution The heat is conducted through a thickness of 2.5mm, with a temperature difference of 5oC. Thus...

Hi all Homework Statement The Debye temperature of argon is 92 K and that of silicon is 345 K. Rank the following in order of thermal conductivity (largest value first): (i) A 1 cm3 cube of silicon at 6 K (ii) A 512 mm3 cube of silicon at 2 K (iii) A 1 mm3 cube of argon at 4 K (iv)...

I'm interested in modeling a system where the material varies along its length, thus the conductivity coefficient would be a function of both T, and x. k(T,x). For starters, if I assume negligible change w.r.t T, then he heat diffusion equation would be d/dt(k(x)dT/dx)=0. Correct? What if k just...

I am working on some basic calcs for heat transfer from polyethylene pipe. My numbers are not working out right so I need a little refresher. The PE pipe would have a TC of about .46 W/(m.*C). to get to BTU/(hr.ft.*F), I mult by .5779 to get .266. Assuming 10sf of PE pipe, and let's...

Homework Statement A copper sheet of thickness 2.37mm is bonded to a Aluminum sheet of thickness 1.29mm. The outside surface of the copper sheet is held at a temperature of 100.0°C and the Aluminum sheet at 24.5°C. a) Determine the temperature of the copper-aluminum interface. b) How much...

Homework Statement An ice cube at 0.00 °C measures 14.9 cm on a side. It sits on top of a copper block with a square cross section 14.9 cm on a side and a height of 18.1 cm. The bottom of the copper block is in thermal contact with a large pool of water at 92.5 °C. How long does it take the...

Hi, I'm doing a group investigation on external wall insulation for my school building. The walls do not have a cavity and thus it has been proposed to put insulation over the exterior render of the wall. This is a fairly common building procedure. However, my task is to investigate the...

Homework Statement In a domestic heating system, a room is warmed by a 'radiator' through which water passes at a rate of 0.12kg s-1. The steady-state difference between the inlet and outlet temperatures of the water is 6.0 K. The radiator is made of iron of thermal conductivity 80 W...

1. I would like to test myself on how well I know my information about certain metals, some of them get me a bit puzzled. How would you rate the electrical conductivity of cast iron? Poor, good, excellent or best? Also the thermal conductivity of 304 stainless steel? Poor, good, excellent or...

I would like to test myself on how well I know my information about certain metals, some of them get me a bit puzzled. How would you rate the electrical conductivity of cast iron? Poor, good, excellent or best? Also the thermal conductivity of 304 stainless steel? Poor, good, excellent...

For a nonmetal what determines thermal conductivity is the propagation of lattice vibrations. As T increases these lattice vibrations collide with each other more often. Does this mean that the thermal conductivity will de- or increase?

If thermal resistance is additive, then how can the thermal conductivity of two (or more) materials be combined? Can it? Eg. a wall filled with straw and air, a hollow brick, a mixture of polystyrene and fibreglass wool (just some random ideas off the top of my head).

Hello, i'm doing my prep for my lab experiment tomorrow and have a few questions about the experiment. The schematic is attached. My lab script says the following; 2 questions. It says the precise rate of flow of water through the heat exchanger is unnecessary to know. Is this...

Hi, I was hoping someone could enlighten me on the thermal conductivity of air. I'm aware the λ for air is 0.024. Meaning its a very good insulating material. Much better than the conventional insulating material we use for conventional buildings such as EPS and XPS which are at λ 0.030...

How can I determine the thermal conductivity of two different aerial coolers' tubes, taking into account the ambient temperature of the air? The overall goal is to determine which cooler is able to cool water the best, but the data was taken during different outside air temperatures. Below...

I use RTV silicone rubber to make moulds for hard candy. Hard candy is basically boiled sugar that is poured into moulds at just under 300 degrees F. The castings of hard candy develop bubbles on the surface because the silicone does not dissipate the heat, unlike traditional metal moulds...

Homework Statement One end of a metal rod is maintained at 100°C, and the other end is placed in a large container with ice and water at 0°C. The rod has length 50 cm and a cross-sectional area of 0.8 cm 2 . The heat conducted by the rod melts 4 g of ice in 5 minutes. Calculate the...

Hey all, i'm trying to set up a thermal model of a permanent magnet synchronous electric motor. This by doing a lumped system analysis of the motor. In the thermal network that I've set up, I'm trying to introduce an equivalent thermal conductivity value (W/mK) for the copper conductors plus...

Homework Statement A hot reservoir is maintained at a temperature of 78 oC, and a cold reservoir is maintained at a temperature of 5oC. They are separated by 11.00 cm, and are connected by a cylindrical bar made of two materials. The radius of the bar is 0.83 cm. The upper part of the bar is...

Hi everyone. I was wondering if there is a convention for solving heat conduction problems. Specifically should one account for thermal expansion? The SI units for thermal conductivity are W/m/K. Does m include thermal strains already? It seems for basic problems it would be easier to...

Hi, i'm searching for a material with the following properties: - high stiffness - low thermal conductivity - temperature resistance up to 150°C (not getting too soft at 150°C) - no low friction coefficient (so no PTFE) - good fracture behaviour (so no glass, ceramic) - cheap I've...

Homework Statement The brick wall of a building has dimensions of 4m by 10m, it is 15cm thick with a coefficient of thermal conductivity of 0.8 (Wm^-1C^-1). (a) How much heat flows through the wall in a 12-hour period when the average inside temperature is 20 C and the average outside...

I want to calculate the average thermal conductivity of UO2 by : 1/(To-Tf) * ∫To->Tf dT K(T) any one can provide me anything about the thermal conductivity of UO2 as function of temperature or any measured data in a range of temperature.

Hi I've been trying to find effective thermal conductivity of sintered bronze, especially of that used in self-oiled sliding bearings (like Oilite). I need it to know how much less it is compared to dense copper alloys, eg. tin bronze. So far my search has proven fruitless. It seems that...

Homework Statement So you have a fridge, the walls of the fridge are made of aluminum, plastic and insulation. Which is the most relevant and why for the fridge. Homework Equations Thermal conductivity of aluminum=250 Plastic=.03 insulation=0.035 - 0.16 The Attempt at a Solution...

Homework Statement So the outside of a refrigerator is made up of plastic, metal, and insulation? Which is the most important and why. Homework Equations no equation needed. The Attempt at a Solution I thought that the insulation would be the most important because it reduces...

Homework Statement I was wondering why there is such a disparity between thermal conductivty and how they act in the real world. Ex. If if have 3 cups filled with hot water. The 3 cups are made of glass, plastic and metal. The metal will obviously have way higher thermal conductivity...