Questions tagged [thermal-conduction]
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69
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Heat transfer Calculation for heating polypropylene plastic Nano tubes
I am from electronics background so I don't know much about heat transfer calculation . I am designing PCR thermal cycler which will provide Quick heating and cooling to the solution in the
...
1
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1answer
33 views
Equivalent Resistance Between Two Points in a Wye Network
I am interested in learning how to calculate the equivalent resistance between two points in a wye circuit for application to thermal networks (i.e. I'd like to calculate the equivalent thermal ...
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0answers
30 views
Cold Plate Thermal Resistance
I am designing a cold plate that will have 4 Power Modules Mounted on it. The total power loss from the modules is 5000W(1250W per Power Module). I have simulated the results on ANSYS Fluent and ...
4
votes
1answer
70 views
Filling gaps in heatsink design to improve thermal conductance?
I am currently pondering modifying my laptop's heatsink and am curious whether I stand to gain any benefit at all.
The CPU and GPU (similar heatsink design) reach high temperatures (90°C +) under load ...
1
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1answer
46 views
surface temperature due to constant heat flux
Imagine a hollow cylinder with the outside surface exposed to air (convection). If there is a constant heat flux on the inside surface how would I calculate both the inside and outside surface ...
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2answers
65 views
Boundary conditions at interface for1D transient heat conduction problem in cylindrical coordinates
The problem I am currently working on involves rapidly cooling liquid aluminum in a cylindrical graphite crucible and getting the radial temperature distribution over time, possibly using finite ...
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0answers
32 views
Heat Transfer FEA with matlab
I have to write a matlab code using finite element method to solve this problem. I have solved it as follows but I dont know how to apply it in matlab.
I have to write a matlab code using finite ...
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0answers
28 views
Air Conditioner for an Acrobat Plane
What kind of Freon air conditioner would work upside down? Or somehow make it cut off and start working again when upright? I have a small cabin so it can be electrically driven. I know they have an ...
0
votes
1answer
40 views
Thermal conductivity listed in the rather complicated Btu/s-in.²-°F/in - am I converting this right?
I'm currently working through some rather old documentation which gives the thermal conductivity of a material as 9.8 x 10⁻⁶ Btu/s-in.²-°F/in. There are many typical ways to give a thermal ...
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2answers
71 views
How do I calculate final equilibrium temperature of a pot of water on a stovetop vs. after I add food to it?
So I'm trying to come up with a simple hack to heat up food in a water bath to hopefully +-1ºC of a target temperature, but I really don't understand the physics of it all so much. I'm pretty sure I ...
0
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1answer
93 views
How to calculate heat loss across a process pipe with perpendicular air flow
My thermodynamics knowledge is extremely rusty, so I would appreciate some guidance on how to solve this problem.
As illustrated here, I have a process pipe (steel) with a gas flowing through it (blue)...
2
votes
1answer
55 views
How can I trust a K-type thermocouple purchased from a no-name company?
I am doing some temperature measurements for reliability testing, over an expected range of 16C to 45C. I have an NIST traceable thermocouple thermometer (S220-T8), however it does not come with ...
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14 views
Thermoelectric cooler parasitics
So I'm looking at performance curves for thermoelectric coolers, and it seems like these curves are so misleading as to be useless unless I'm missing something fundamental.
Suppose I have a ...
1
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2answers
50 views
Through which medium is most of the heat transferred down (downwards) a glass tube filled with water: the glass walls or the water column?
If a much hotter object is attached to the tube from the outside, and the heat in question is transferred to the part of the tube that is below the source of heat, so there is no convection.
The ...
0
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2answers
29 views
What happens in Thermal boundary layer in a flow with cooled plate?
All the notes on Thermal boundary layer(TBL) explains the growth of TBL over a heated flat plate ie cooler fluid is flowing over a hotter plate (heat is flowing from the plate to the fluid).
How does ...
2
votes
2answers
236 views
Why does the thermal boundary layer(TBL) thickness increase with decreasing Prandtl number?
Consider a liquid flow in which, keeping all else constant, we can vary the thermal conductance(K). Now, if we increase the thermal conductance of the fluid the Prandlt number will decrease. I read ...
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1answer
65 views
How to heat up a swimming pool with the sun
I'm trying to figure out how to heat my pool most efficiently using the sun.
Currently, I've got 2 black panels (made up of a bunch of black pipes) on the roof that the pool pump cycles the water ...
3
votes
1answer
89 views
Trapping sun heat the most - greenhouse
Greenhouse have recently caught my attention lately, which yesterday I posted in Why greenhouse's inside temperature never been infinitely hot?
From what I understand recently, greenhouse gases traps ...
1
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1answer
35 views
What material might by used to 'staple' coils down in this stovetop element?
I have the stovetop element shown in the image below. If you look at the coils, they're fixed down by what look like little staples. I'm wondering what material those staples might be. The surface ...
2
votes
0answers
37 views
Internal Tent Temperature
Here is the problem I am working on:
"Consider a perfectly sealed polygonal tent with the sun directly overhead. The solar irradiance of a surface 90° to the sun’s rays is 1,000 W/m2. However, ...
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0answers
26 views
how to obtain solution of this bessel equation using Frobenius method
Given this equation:
$$
\frac{1}{r}\frac{d}{dr}\bigg(r \frac{dT}{dr} \bigg) - \bigg(\frac{2h}{bk} \bigg)(T-T_a) = 0
$$
I can let $x=r\sqrt{(2h/bk)}$ and $z=T-T_a$ to obtain the bessel equation using ...
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1answer
35 views
Is it just surface area alone that causes bridges to freeze?
Scenario: Object 1, a bridge freezes over do to the surface area exposed to the below freezing air. Object 2 has the same surface area exposed to the same air, but its base sits on the ground that is ...
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3answers
45 views
Material selection of heating element
I am interested in heating coils which are heated using Ohmic/Joule/resistive heating - specifically, how the material for the heating coil is selected.
When I read about heating coil materials - ...
-1
votes
2answers
61 views
Heat conduction in a hollow cylinder with low conductvity coefficient - Why do I get negative temperatures?
I have a hollow cylinder with a heat source inside. The generated heat flow is $\dot{Q}_g = 14\ 962 \ \text{W}$ , the cylinder has the radius $r = 20 \ \text{mm}$, the length $l = 50 \ \text{mm}$ and ...
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votes
3answers
95 views
Are there differences between Ice Packs?
My girlfriend will get a refrigerator from the landlord, but right now she hasn't one. But she has a freezer. So we will get ice packs (images: 1, 2, 3) and use a cooling box for the time.
Now I was ...
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0answers
10 views
Heat Conduction/Convection Along discontinuous tube
I have a question regarding heat conduction/convection. I have a metallic tube over which a rope heater is wound, supplying power. A glass tube and a 2nd metallic tube lies at the exit of the first ...
1
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1answer
72 views
Analytical solution of thermal stress in a bi-metallic cylinder
As a side project I have looked to solve using Python an analytical solution for one-dimensional transient heat transfer in a thick cylinder with cladding on the inside surface, wherein the fluid in ...
-1
votes
1answer
50 views
Heat transfer for a copper rod
For a copper rod heated by a heat gun, why might the temperature of the rod continue to increase for a short time after the heat gun has been removed as the heat source? With reference to transient ...
-1
votes
1answer
73 views
Heat Transfer Problem , 1 Dimensional Conduction Extended Surfaces
enter image description here
So I am having issue solving this problem, I solved one part by the fact that in the given distance of 2L , 2 tubes are involved so I can find the heat conducted per unit ...
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0answers
36 views
How to calculate heat transfer between two solids in a medium?
If I have a cuboid block of metal and there is a cylindrical source of heat input (A) and I want to determine the heat energy at B (also cylindrical) how would I do this?
I understand considerations ...
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3answers
118 views
How to calculate the volume of air required to keep electrical box cool?
I have a steel electrical box that is 15 cm x 15 cm x 10 cm. The weight of the box is 1kg. Inside the box is a relay that loses 30 Watts of heat while in operation (it's attached to a heat sink that ...
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23 views
What material characteristics are most important for heating element material selection?
I want construct a heating element by screen printing a flat coil pattern of conductive paste onto an insulated substrate. This conductive paste consists of a powder of conductive metal contained in a ...
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2answers
148 views
Time to change temperature inside the box
I have an interesting problem here.
I have a box of certain dimensions. Inside of the box is some insulation and another box, from the same material as the outer box. I know everything possible about ...
0
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1answer
94 views
Wire heating and heat transfer in a cylindrical pattern
I have a series of copper coils with ¼” cooling plates between each coil. The cooling plates will be manufactured from aluminum and cooled using copper tubing. There are seven in series, and a plate ...
0
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2answers
220 views
Simple Thermal Analysis for sealed Aluminum box with 3.7 Watts of heat generation internally
I am looking for a starting back of the envelope calculation to determine if an aluminum box with just free convection can dissipate 3.7W of internal heat generation or if I need to think about adding ...
0
votes
1answer
65 views
In a warmer/sunnier climate, window (or roller shutters) superior to curtains?
When -on a hot day- the sun is incident on a window covered from the outside by a closed window shutter, the resulting heat is absorbed by the layers of air surrounding the shutter, subsequently ...
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1answer
43 views
Wall temperature of pressure cylinder - Boundary condition
I have a thick-walled pressure cylinder, that transports fluid and experiences only internal pressure. During the process, the outer wall temperature is measured. And I have no clue about the inner ...
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1answer
160 views
Heat Transfer in Different Wire Configurations
I am trying to create a program which estimates the final temperature of a magnet made of copper wire. I have different configurations in mind, but I will start off with a straight square wire with a ...
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39 views
Can radiant induction heat thermally decompose wood
Is it possible to thermally decompose an indicator like wood in a induction heating container made of stainless steel if the induction frequency is low enough to heat the container about 1000°c.
...
3
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2answers
60 views
Powder form of material with high thermal transfer
The Engineering Toolbox presents a chart of "common" materials and their thermal conductivity coefficients. I'd read or learned some time ago that diamond was superior in this respect. The chart shows ...
2
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0answers
21 views
DIY Thermal Solution [closed]
What would be the best way to design a sealed computer containing a gas or liquid circulated by a fan/pump to cool the components? ( With a metal case ) Then the computer would not be susceptible to ...
0
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1answer
62 views
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,...
2
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0answers
43 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 ...
5
votes
1answer
69 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
1k 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
71 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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2answers
166 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 ...
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votes
2answers
1k 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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vote
2answers
47 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 ...
3
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4answers
192 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 ~ ...
