Read about thermal conductivity | 39 Discussions | Page 1

  1. E

    B Rate of conduction heat transfer with different hot-side and cold-side areas

    When we measure 'the rate of conduction heat transfer'=Q , we assume that the hot side and the cold side's area are same. But if the both side's area is different to each other, how can i know the rate of conduction heat transfer? like below figure. Would you like to help me?? Thanks.
  2. Thatrandomdudeacross

    I Tank Heat Transfer

    I'm trying to find a heat transfer equation that includes time. Metal tank, partially filled with liquid. I need to find the time it would take for the temperature on the outside of the tank to drop from θ2 to θ1, given thickness, metal and liquid's properties, and tank dimensions
  3. T

    I Heat capacity vs Thermal conductivity in a LN2 bath

    I worked on a lab experiment that was meant to measure heat capacity but left me with some other questions. The students measured the mass of a cup of liquid nitrogen as it boiled off, recording mass vs time. Then they drop a solid object into the bath, one experiment with a small bit iron...
  4. B

    I Solution of the 1D heat equation

    $$\frac{\partial T}{\partial t}=\alpha\frac{\partial^2 T}{\partial^2 t}$$ with an initial condition and boundary conditions $$T(x,0)=T_0$$ $$T(L,t)=T_0$$ $$-k\left.\frac{\partial T}{\partial x}\right|_{x=0}=2A\cos^2\left(\frac{\omega t}{2}\right)=A(\cos\omega t+1)$$ where $A=V_0^2/(8RhL)$...
  5. K

    Thermal Conductivity Problem-- Two Reservoirs

    Suppose that a large mixture of ice and water is in thermal contact with a reservoir which contains a large quantity of water and steam. Assume that both the ice/water bath and the water/steam reservoirs are otherwise thermally isolated and at a constant temperature. The only contact between...
  6. A

    PV/T system

    Hello! I am a materials engineering BSc student currently writing my bachelor thesis. The topic of my thesis is regarding the PV/T system and the best material choice for the interface between the glass/glass PV module and the heat mat. I would appreciate any ideas for material with best thermal...
  7. Martinez43

    Making a thermos

    Homework Statement Hello, As part of my engineering orientation class, my team and I have to make a device that can keep a beaker of water warm. We have a list of materials we can and cannot use, but my team and I have decided on aluminum foil and maybe wood. We don't actually have to build...
  8. T

    Misc. Thermal Dissipation problems

    I am working on a project; a computer case made out of wood, most likely oak. I was wondering if two fans (one bringing air in, on taking air out) would be enough to keep the system at a stable temperature. I wasnt sure because i know most cases are made of thin metal which conducts and...
  9. Stephen Lanford

    I Possible error sources in thermal conductivity experiment?

    Hello, my name is Stephen Lanford and I am currently working on a Physics II lab. I am solving for the thermal conductivity of four materials (glass, plexiglass, pine, and sheetrock) using data from thermal conductivity experiments. The experiments consist of a steam chamber at 100 C, a block...
  10. fluidistic

    I How come electrons and phonons lead to the heat equation?

    Phonons on their own lead to the common heat equation. One sees that for example in insulators or non doped semiconductors. However in metals (or conductors), the electrons are the ones that are mostly responsible for the heat transfer, which extremely surprisingly to me, is also of the form of...
  11. katelr

    I When/How does thermal radiation stop (if it stops) and conduction

    Consider two solid objects in the vacuum (of different materials, if you will) at different temperatures approaching each other until they make "perfect contact" through flat surfaces (no gaps or defects, so that thermal contact conductance effects are absent, even though interfacial thermal...
  12. R

    Magnetic conductive material but thermally non conductive

    HI, I have application where i need to lift metal plate, 3kg weight, ( 3mmX 15mm), 250degree.C hot, for the period of 1min and put it back. For lifting purpose i am using actuators. As i have no opportunity to make hole in plate i have to use magnet for lifting purpose. I got Electromagnet...
  13. M

    Chemical potential using Boltzmann equation

    Homework Statement I must calculate chemical potential using the Boltzmann equation in relaxation time approximation $$f=f^0-\tau v_z^2 \partial f^0/\partial z,$$ where ##f^0## is given as $$f^0 = 2(\frac{m}{2\pi\hbar})^3 \frac{1}{\exp{\beta(z)(\frac{mv^2}{2}-\mu(z))}+1}$$ I have to consider...
  14. J

    I Question about thermal conductivity in thermoelectrics

    Does the phonon thermal conductivity account for a large part of the total thermal conductivity in thermoelectric materials like Bismuth Telluride? As far as I know, the phonon conductivity is the largest contributor to the total thermal conductivity in semiconductors. Is this still true for...
  15. T

    Finding thermodynamic properties for a Zn-Mg Alloy

    Hi! I am using a Zn-Mg alloy (52% and 48% respectively) as a phase change material in a thermal energy storage system, but I have been unable to track down important properties, such as specific heats and thermal conductivity. Is there any way to approximate these relatively accurately given...
  16. knc

    Heat transfer in series and parallel

    Homework Statement Homework Equations P = k A \frac{dT}{dx} The Attempt at a Solution a) Assuming steady state transfer, energy transfers through rods at the same rate everywhere. Letting T be the temperature at the point of welding. P_1 = k_1 A \frac{T_h-T}{L} \\ P_2 = k_2 A \frac{T -...
  17. N

    B Has thermal conductivity any relationship with energy?

    More thermal conductivity means there's more energy?...
  18. N

    Heat Transfer From Resistance Element to Metal Component

    Hello Physics Forums! My problem is as follows. I have a device that produces heat via Nichrome coils. I want to heat another small piece of metal (in this case stainless steel) with those Nichrome coils. I need to reach 175 degrees C, and so far I haven't found a readily available thermal...
  19. L

    Thermal Conductivites between two dissimilar metals

    1. Homework Statement I've been failing to find examples dealing with "longitudinal" thermal conductivity and how two objects in contact with each other would affect the heat flow compared to not being in contact at all. Problem: Given the following information, determine the thermal energy...
  20. Muhammad Syahril

    B Your Opinion On This Solar Cooker

    First of all, even I did mentioned Solar Cooker, the main goal is to reach most temperature of 500ml of water in 30 minutes. Basic information that I have is some material with different thermal conductivity. I seek for simple english language and a bit complex physics language. The idea of...
  21. Ravi Singh choudhary

    Which will boil faster?

    Homework Statement Case 1: Which will boiling faster the container having steel ball dipped in it or container having only water? Case 2: Which one will attain thermal equilibrium faster? Consider balls are just in middle of the container. every condition of each the cases have same volume...
  22. L

    Heat Loss

    Homework Statement In each of the following, state and explain which container will have the hotter liquid after thirty seconds: a) You pour equal amounts of of hot coffee into two cup s from a percolator. The cups are the same general size and shape. One is made from heavy china one is made...
  23. F

    Max thermal conductivity required for heating elements

    I'm designing an oven and want to ensure that the insulation I specify has a low enough Thermal Conductivity (k) to resist excessive heat loss. I determine heat loss (Hout)with the following equation: Hout=A*U*(T1-T0). U is dependent on k (U=k/L). I omitted the heat transfer coefficient in...
  24. J

    Relationship between pressure and thermal conductivity

    Homework Statement I would like to derive an equation that relates the thermal conductivity to the pressure using the kinetic theory of gases. However, I assumed that thermal conductivity was independent of pressure. Homework Equations I know that P = 2N/3V (1/2mv^2) Also: I believe that...
  25. Y

    Insulator density and thermal conductivity

    How does insulator's density affect its thermal conductivity? For example, considering such insulators as rock wool, It seems that the thermal conductivity should increase with an increase in density (due to elimination of 'air pockets'). However, experimental results, in many cases, look more...
  26. fredey

    What would happen if? you heatsink earth and space

    It is a thought I just thought of with all the wonderful attention that climate change has been getting recently. The thought goes as follows: The world has ever increasing entropy as the whole universe has so. With humans adding to this effect even if green house gases curbed due to this...
  27. N

    Which will have a higher temperature?

    Wood and Copper are heated upto a steady state condition which will have a higher average of temperature at points ? Please state your mathematical approach 1. Homework Statement Dimensions remain same for both the materials as well as the temperatures both are heated to is the same Homework...
  28. K

    How to replicate electric blanket? (Project)

    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...
  29. S

    Two rods are connected one silver and the other gold.

    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...
  30. @PinkGeology

    Why would hot fluid retain more % heat at lower flow rates?

    Homework Statement Hot magma (1500 K) is flowing in to 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...
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