Thermal conductivity Definition and 185 Threads

I was hoping someone could help me with a project I am doing. I have contacted a manufacturing company thatmakes thermal wrap material, and I need to see if this will work for my project. According to the manufacturer the material is 1/16" thick - this info was also given to me by the...

Homework Statement One end of a metal rod is maintained at 100 degrees C, and the other end is maintained at 0 degrees C by an ice-water mixture. The rod is 60 cm long and has a cross-sectional area of 1.25 cm^2. The heat conducted by the rod melts 8.50 g of ice in 10.0 min. Find the thermal...

Homework Statement we have a metalic bar with thermal condutivity of 200w/(m*k) it has an area of 20 cm^2 which is in contact with with an heater that delivers 200 W and is at 300ºC. the metalic bar has a thickness of 1cm The two questions are: a) once the system have entered a...

How do I go about deriving the thermal conductivity of graphene (specifically, in the low temperature limit) when I'm given the phonon dispersion relation? I haven't been able to find anything explaining how the dispersion relation relates to the thermal conductivity in materials. (this is...

I mean how can i analysis the thermal conductivity of two structures with their phonon spectrum. thank you!

Homework Statement i need to find the thickness of the insulating material that is needed to block out the heat that is coming into the room. the area of the affected wall is 3.3m2 the temp in first room is 18 degree celsius while the 2nd room is 45 degree celsius. the thermal...

Homework Statement obtain an expression for the thermal conductivity of a gas at ordinary pressures. The thermal conductivity of Argon (atomic weight 40) at STP (standard temp and pressure) is 1.6e-2 W/mK. Use this to calculate the mean free path in Argon at STP. Express the mean free path...

Hi Experts I'm joining aluminium fins to an aluminium body as part of a heat exchanger project. There are a number of variables here and I would like to evaluate them to achieve the best results. The best (simplest ?) method I can come up with is to attach several groups of fins to a common...

I understand that thermal conductivity is W/(m.K) and u-factor is W/m² K. Obviously U factor is energy transfer over an area but how does this compare to thermal conductivity?

Hi to all Can some one help me for below question: What is different between "isotropic thermal conductivity" with " anisotropic thermal conductivity" ? where and when we must use isotropic or anisotropic ? which one is more accurate? I solve an example in a FEM software and it is...

Thermal Conductivity , k , for water is .1455 cal/sec/ meter * C ( converted watts to cal/sec) Q/t = k* A delta T/ d A= area M2 d = thickness of water/ice boundary layer Suppose I want to calculate time for 100 grams of ice to melt ( 8000 calories absorbed from surroundings by conduction. I...

I'm currently running RELAP5-3D to model a molten salt reactor and I require the thermal conductivity of graphite. Is there anyone that is aware of this value, or can inform me of a proper resource? Thanks!

We have a customer asking us for the thermal conductivity of a product we sell. None of the engineers have that number. I can think of a simple experiment that might do it, but I don't know the math. I want to take a piece of this material (it's a pipe), put a cap on the bottom, then...

Hey everyone! Got an interesting problem here, I am thinking I did it correctly but I wanted to see your opinions. Here is the problem.. A 0.2-m-thick plane wall is constructed of concrete. At steady state, the energy transfer by conduction through the wall is 0.15 kW/m2. The inside...

Homework Statement Ice has formed on a shallow pond, and a steady state has been reached, with the air above the ice at -9.6°C and the bottom of the pond at 5.5°C. If the total depth of ice + water is 2.1 m, how thick is the ice? (Assume that the thermal conductivities of ice and water are...

Homework Statement solve d/dx(kdT/dx)=0 where k is linear function of temperature k=k(0)(1+BT) Homework Equations this is the solution T+BT^2/2=Ax+C The Attempt at a Solution i opened the equation so that it becomes equal to dk/dx*dT/dx+kd^2T/dx^2=0 i subtitute the...

I'm working on a model that needs to calculate the approximate thermal conductivity of a mixture of gases. I'm having trouble finding a model which is being used by one of my sources but is not cited and I can't seem to find a source for it. I'm hoping that someone here might recognize the model...

In the case when heat is flowing at a steady state through two materials with different thermal conductivities, the classic Q/t = A(T2-T1)/ L1/k1 + L2/k2 applies. In this case T2 is fixed and the two different k values are combined. In the case of cooling , Newtons...

I am trying to decide what alloy I should use in an experimental heat transfer device. I am considering 2 materials- 304 Stainless Steel and SAE 516 Grade 70 boiler steel. I want to choose the material that has the best conductivity characteristics. To be clear, I want the material that has...

Homework Statement Quick question about Thermal Conductivity, I have 2 plates each with thickness x, with respective thermal conductivities A and B. what is the effective thermal conductivity? Homework Equations Q/(delta t) = -k(Area)dT/dx where k= thermal conductivity A or B...

Homework Statement Design a portable container that will keep medicines at around 4 degrees celcius for at least 12 hours. Homework Equations Fouriers law, q=kA(T1-T2/L) Thermal Resistance=L/kA q=heat transfer rate (in W) K=thermal conductivity (W/M*degrees C) A=cross sectional...

This relates to design of a heat spreader. My intuition is failing me and I'm not familiar with this area of thermodynamics/heat flow. Assume I have a heat source, attached to a large flat surface used as a heat spreader/sink. The size of the source is negligible w.r.t. the surface area (A)...

Homework Statement Rod of cross sectional area A and length l has its left end held at constant temperature t1 and its right end held at t2<t1. If the conductivity varies with distance from the left end, x, according to the relationship k= x/R + k0 (R and k0 are positive), what is the steady...

Hi there, Please, I would like to know if the Thermal Conductivity of a liquefied gas increases or decreases when becomes a supercritical fluid. Also, I would like to know how is the relation between the molecular mass and thermal conductivity of a liquefied gas and a supercritical fluid...

HI I would like to test the thermal conductivity of r wall by K=Q*d/ A (t2-t1) K =conductivity d+=thickness A= area Q= heat flow my problem how I could simulate heat in my experiment and how I will measure the heat flow? could you please help me. Kind regards

Exterior commercial frames (.053") embedded in a concrete wall 8" thick with 3" layers of polystryrene (3# density) on each side of concrete cavity. Frame rests on foam inside and outside of building. Frame is grouted solid with poured in place concrete. Is there an appreciable (to be...

Hi :) I'm having difficulty with finding the relationship between specific heat, c, and thermal conductivity, k and cannot answer these questions - Six objects are placed in a 500 F (260 C) oven and allowed to reach thermal equilibrium. Each object has a mass of 1.0 kg . The specific heat and...

Homework Statement This is my first post on these forums, this problem is part of a lab and its part my end of year result but we never did anything on it in class so i have'nt a clue how to do it. Help would be really appreciated The handle of a freezer door 12cm thick is attached by two...

Homework Statement A wall is insulated with glass wool of thermal conductivity K = 0.046 W/m oC. What is the rate of heat loss (in W) through an area 1.0 m wide by 1.5 m high, insulated with a layer of glass wool 20 cm (.2 m) thick, if the temperature difference across the layer is 20.0 oC...

Homework Statement A Cylindrical Tube of Length 35m, inner radius = 2.5m The tube is lines with 6cm thick insulation where k = 4X10^-5. The inside temp=25 degrees celcius Find the rate of heat delivered if the outside is -35 degrees celcius which keeps the inside temp at constant 25...

Homework Statement The passenger section of an airplane can be thought to have a shape of a cylindrical tube. For a small airplane, the tube is 35 m long and has an inner radius of 2.5 m. The exterior of the tubular wall is lined up with a 6- cm thick layer of insulating material of thermal...

Homework Statement To summarize, I am given 6 objects and their corresponding specific heat capacity and thermal conductivity values. All objects have the same mass. The question is asking me to rank the objects based on temperature if they are put in a hot oven until they reach thermal...

Is it possible to calculate thermal conductivity of a material given just the delta-T at steady state and the material thickness? I have material that is 1/2 inches thick and has a 145 degree-C diffential @ 220C. Can I calculate its k-factor from that data alone? Thank you.

is there any corrolation between thermal conductivity coefficient and molecular wieght Mw according to the units [K] W/(m·K) it is independant of mass units (kg or g/mol etc) in my question i am asked to show with a graph, but i have no idea what graph they are talking about

Hello! I'm writing an essay on 'relationship between density and thermal conductivity'. Could anyone explain to me the relationship? e.g. is it proportional or reciprocal? I'm kind of closing to the answer by doing an experiment. I took two concrete blocks with different densities and got...

Hello! I'm writing an essay on 'relationship between density and thermal conductivity'. Could anyone explain to me the relationship? e.g. is it proportional or reciprocal? I'm kind of closing to the answer by doing an experiment. I took two concrete blocks with different densities and got...

Hello! I'm writing an essay on 'relationship between density and thermal conductivity'. Could anyone explain to me the relationship? e.g. is it proportional or reciprocal? I'm kind of closing to the answer by doing an experiment. I took two concrete blocks with different densities and got the...

Hi all In the following link it says: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thercond.html "For metals, the thermal conductivity is quite high, and those metals which are the best electrical conductors are also the best thermal conductors. At a given temperature, the thermal and...

Hi all I'd like to heat up a mile of buried copper cable to roughly 100 deg C. The centre core is 80mm dia solid copper with impregnated paper insulation. Maximum spot temp is 150 deg C. I can expose the core at each end and clamp on a heating element. I've got plenty of time =...

hello! I'm investigating on thermal conductivity of concrete blocks. I've got an equation for calculating K, which is Fourier's law. Q'=-k×A× ∆T/l I have to make the experiment simple as possible as i can. My plan is to heat one side of a block of concrete and measure the temperature difference...

Hi all I want to convert thermal conductivity to thermal conductance. The problem is with the units. for thermal conductivity the units are [W/(m.K)] and for thermal conductance the units are [W/K] For E.g for copper thermal conductivity is 400[W/m.K] how can I convert it to thermal...

Help! Which has higher heat conductivity: water or air? And could you give me a proof as well? Regards, Quan Chi

Hi Everyone, I have a thousand data points that create a graph of Copper's Thermal Conductivity as it changes from a temperature of 4.5 K to 300K. These points create a somewhat bell-shaped curve, and I have been trying to find the equation to this curve so I can integrate it. I have...

a little guidance with thermal conductivity please... Homework Statement there isn't really a problem statement, as its a lab write up I'm doing. we had two blocks of the same metal, one at room temp and one at a fixed temp of almost 50 degrees. a Rod of different metal was put between...

can anyone explain the relationship between specific heat and thermal conductivity?

Homework Statement I have plate of glass pressed between a hot plate on top and a insulating surface below. The idea is to be able to predict the temperature of the glass plate and the thermal gradient through the plate as well at any time. I know the hot plate is at 400 deg F, that it is an...

hi, I would appreciate any help i could get on this, thanks. I've to estimate the heat loss from a person, immersed in water at 10ºC if he is wearing a 3mm wetsuit did anyone know how to process? thanks a lot jerem

Homework Statement One end of an insulated metal rod is maintained at 100^\circ C and the other end is maintained at 0.00 ^\circ {\rm C} by an ice–water mixture. The rod has a length of 75.0 cm and a cross-sectional area of 1.40 cm^2. The heat conducted by the rod melts a mass of 7.85 g of...

Hi, I have read that Thermal Conductivity means: “The thermal conductivity of a substance is the quantity of heat in cal/sec passing through a body 1 cm thick with a cross section of 1 sq. cm when the temperature difference between the hot and cold sides of the body is 1 deg. C.”...

Hi could anyone advise me to weather I am right in thinking when using equation one to calculate the thermal conductivity that Cv is the molar heat capacity and is calculated by use of equation two for an ideal gas such as argon? k=n*<v>*mfp*cv / 3*NA Cv,m = (3/2) * R Any hints would be...