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Questions tagged [thermal-conduction]

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1answer
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Conductive Heat Transfer calculation over time

I am trying to heat the oil in a 1/2 inch thick rectangular steel box by using an Insulated heated blanket covered on all 6 faces of the box, the working conditions of the operation are at -50 Celsius,...
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0answers
35 views

Flow of hot gasses around the pipe

I have the following problem: there is a copper pipe getting through a wooden wall. On one side of the wall (hot side), I have elevated temperature which is defined by radiation and convection. On the ...
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1answer
63 views

Easily compute a good approximation of heat conductivity of cooled semi-vacuum (water vapor + air)

I am preparing a classroom demonstration about heat, including a demo of how a satellite loses heat only radiatively, since it's flying through a vacuum. I'd like to make the vacuum-production ...
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2answers
58 views

Calculation for heat transfer rate / cooling capacity for air cooled solid

I have a pipe which is channeling air flow from a compressor with a known mass flow rate and temperature. I can adjust the mass flow rate (power setting) and measure the delta T for the temp of air ...
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1answer
55 views

How cold for lack of heat?

I know that on the moon, while the daytime surface temperature can be above 270° F, in the shade but a few feet above the surface temperature can get quite low. Wondering whether a similar phenomenon ...
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1answer
64 views

Thermal oil in Boiler not reaching desired temperature

The thermal oil Feroline U in Boiler is not gaining the desired temp of 240 Degrees. We have physically measured the temp using digital thermometer at a distance of 20 cm where the boiler temp sensor ...
3
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1answer
86 views

Use two passive CPU coolers on one single CPU?

I aim on building a silent, completely passively cooled PC, with no moving parts at all (I am aware that it is cheaper to go for an inaudible computer instead, using low speed fans. This is not the ...
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0answers
28 views

Best model to describe this scenario of cooling?

I have a block of CFRP (Carbon Fiber Reinforced Polymer) that has defects (back-drilled holes) in it. This sample was exposed to a source of heat for sometime (say 30 seconds) and the source if ...
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0answers
28 views

Working fluids at 1400C

There is a startup that is developing technology to store energy using the latent heat of silicon melting/freezing. The high energy density and high temperature (high Carnot efficiency) make grid-...
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2answers
35 views

Thermal Conductivity? Units On a Data Sheet

I've been trying to find the value of thermal resistivity for some linear disc resistors. I know that Thermal Resistivity is the reciprocal of Thermal Conductivity but the thermal conductivity on the ...
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4answers
81 views

Rapidly cool a flue gas without water circulation

I am a newbie at this!! For an experiment, I have a diesel generator that releases hot flue gases at 150-160 Degree Celcius. I want the output gas to be at less than 75 degrees for a duration of ~ ...
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0answers
407 views

What is the gray-body emissivity value of air

Wonder if anyone would know what is the average thermal emissivity value of air relative to blackbody at near room temperatures? I am looking for that magical number between 0 and 1. Looked everywhere ...
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1answer
65 views

Insulator thermal resistance

I have a machine that has power output of 2750 watt, which is blasted to a insulator foam with thermal resistance of 2.1 m2 kelvin/watt where the insulator is 5 cm thick and it drives the heat into ...
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2answers
503 views

Calculating R-value from temperature differential

A home windows installation rep gave me a quote today and conducted the following temperature differential demonstration. Alice pointed a heat gun (with a surface temperature of 165F) at the interior ...
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2answers
67 views

Winding a wire heating element after a few uses

I bought recently 10 meters of Kanthal A1 AWG18 wire, which is a type of heating element (FeCrAl alloy). I intend to make a coil out of it, but it's no use doing that right now, I need more of it for ...
2
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1answer
104 views

How thick do I need to make the insulation in my homemade furnace?

(This is probably a simple question, but I've been staring at it so long I'm not sure I know how to do it any more. I have an Excel spreadsheet with like 3 different ways to calculate this, and they ...
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3answers
63 views

Temperature of a material in a furnace

I am conducting few trials for checking the placement of a thermocouple on a valve for measuring the temperature of the valve and the material is an X45 alloy. You can see the slot taken on the valve ...
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2answers
92 views

Heat Loss in Typical House

I recently looked up the recommended insulation value for my area (7) and was surprised how much lower the wall insulation value was shown to be. As you can see it is almost a third of the recommended ...
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1answer
64 views

Most effective heat transfer in a vertical pipe with small top/bottom temperature difference?

What would be most effective way to transfer heat in the following situation? Specific conditions: A vertical cylinder or pipe, 30-100cm long, 5-10 cm in diameter, heavily thermally insulated except ...
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0answers
27 views

Heat switch material

Sort of a general question, but does there exist or might there exist a sort of thermal switching material? A material that could be switched from a thermal insulator (maybe more of a thermal ...
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3answers
740 views

Does good electrical conductivity imply good thermal conductivity?

Typically materials which are good conductor of electricity are also good conductor of heat, and vice versa. Are there notable exceptions?
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1answer
41 views

Heat Transfer From Resistance Element to Metal Component

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 ...
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3answers
76 views

Radioactive Materials to Energy AT HOME

Is there a way to use a radioactive elements (Americium in my case, but for demo, any radioactive material) to create a usable amount of energy (Power small LED?) AT HOME! Using materials that can be ...
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0answers
56 views

How are most sheet style nichrome-based heating elements constructed?

I have noticed that nichrome is a common resistance wire used for various heating purposes. I have seen it used inside what seem like glass tubes (like on an electric stove) and just floating in coils ...
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0answers
60 views

Thermal Conductivity of Concrete using Cubic Model

In ACI 122R-02 an equation is provided for calculating the thermal conductivity of concrete using a cubic model. The equation is as follows: $$ k_{c} = k_{p}\left [\dfrac{V_{a}^{2/3}}{V_{a}^{2/3}-V_{...
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0answers
39 views

Estimating heat flow

I want to estimate the magnitude of the heat flow coming through my roof. The roof composition is: sheet metal - 15 cm of rock wool - sheet metal. The measurements I have at my disposal: Ambient ...
2
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1answer
277 views

Convective heat transfer coefficient in finite difference method boundary conditions

Suppose there is a cubic material with an internal heat source ($\Delta q / \Delta t =$ Constant), and is immersed in a sufficiently large amount of water. Now I would like to use finite difference ...
2
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1answer
257 views

How can I determine the thermal conductivity of an open container?

I want to know the heat conduction coefficient of a cup in order to investigate why tea cools at different rates in different containers. I know the cup is mostly plastic and paper. How do I determine ...
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1answer
2k views

How to calculate temperature rise on AC induction motor in an evaporative cooler centrifugal blower?

A neighbor recently asked me if his evaporative air conditioner was running correctly because he felt the blower drive motor and it was too hot to leave his hand on it for long. I was surprised to ...
4
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1answer
69 views

Relationship between thermal conductivity and reaching the steady temperature?

The diagram is for three materials with different thermal conductivities. I think number 1 is the material with higher thermal conductivity because it transfers the heat faster so it gets to the ...
2
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1answer
901 views

How can one make graphene cables?

You might see in this short, 2-minute video that billionaire Manoj Bhargava talks about creating cables from graphene to conduct heat from the underground sections of the earth to the surface. But as ...
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5answers
2k views

Are there any materials known to be sound-insulating but thermally-conductive?

Are there any materials known to be sound-insulating as well as thermally-conductive? Cost is not an overriding concern, but preferably costing "reasonable amounts" and much less than national ...