Questions tagged [thermal-conduction]
The thermal-conduction tag has no usage guidance.
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Measure and calculate thermal properties of a material
Can someone explain to an EE how I would go about measuring the thermal properties of a material? I need to measure the thermal impedance, expansion, and conductance (k) of an epoxy, and the ...
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Thermal batteries: Can the max temp inside a battery be greater than the heat pump max operating temp?
I'm curious about thermal batteries,
Let's say I have a heat pump with an maximum operating temperature of 100 °C, that is to say, the heat pump can "collect" thermal energy and heat its ...
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The Heat Generation and heat flux both in General Heat Conduction Equation
How would I incorporate both heat generated within and element and heat flux from external to the element in GHCE.
For example,
Let there be a thick wall of thickness 'L', with internal heat ...
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Battery thermal loss
A copper bus bar is subject to a short circuit current of 500 A for 10 s. The section of the bus bar, through which the current flows, has a length L = 50 mm and a cross section of A = 20 mm^2. ...
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Where can I find thermal conductivities of low carbon steels, i.e., AISI 1020 Steel in 8th edition of Perry chemical engineering handbook?
I need thermal conductivity data of carbon steel AISI 1020 for shell and tube heat exchanger design, but I cannot find it in Perry chemical engineering handbook, which is supposed to have all basic ...
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Calculating the convection coefficient of a green roof
as part of a course I have to calculate heat transfer through a green roof. I'm using Python to carry out an assessment over twenty years. The data I have are irradiance, wind speed, air temperature, ...
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How to calculate internal convection loss in a sealed container?
Say I have a box with a 1m x 1m x 1m interior wall dimension.
The side walls and the floor are 10cm of styrofoam, with a thermal conductivity of 0.03 W/m K.
The top is 1cm thick opaque plastic with ...
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Blower door DIY test
Since in my area there is no way to do a blower door test for a house, I was thinking to do a DIY blower door test. Here is my test scenario:
Preheat the house before testing to have 10 degree ...
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Heat convenction through double pipe
I have a realistic scenario which involves a double contained PP plastic pipe which a section of the pipeline is placed outdoor. What I want to determine if insulation is required at all. The media is ...
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R value of a hole?
Suppose I have a room, 10x10x10m with insulated walls (R-value: 4) and a single double-pane window 1x1m (R-value: 0.35).
Now the total thermal power required to keep the room at a desired temperature ...
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Can $R$ value be estimated by change in temperature over time?
Suppose a closed sphere with a hull and an $R$-value of $10$ m2 K/W and a radius of $1$ m. Suppose the temperature inside of the sphere is Ti, the temperature outside is To. The inside temperature is ...
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Volume of air going through a hole with a temperature difference, and kWh of energy
Let's say we have a square hole of 2cm x 2cm in a wall.
The inside temperature is 20°C, the outside temperature is 10°C, so $\Delta T = 10$.
This creates a flow of air. Let's say the velocity is $1\ ...
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Configurating heat transfer between parts
I am new to Ansys, so sorry if I have some misunderstood parts. I am doing a Steady-state Thermal simulation of a PCB with some of its components. I am currently simulating only the highlighted ...
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Water through a Copper-Coil Heat-Exchanger: How much tubing will be enough?
I am making a hot-water tank for a boat. Within it will be a copper-coil heat-exchanger.
Because copper tubing can be rather expensive, I am trying to better understand the design beforehand, and ...
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Minimizing heat transfer to the contents of a non-airtight pipe
Consider the following simple (half)pipe setup:
The grey part is a galvanized-steel half-pipe.
The green part consists of the ABS plastic non-airtight top lid and an internal layer of ABS plastic ...
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Diffusor for uniform illumination
I have an LED with a beam angle of 120° and I need to illuminate an area in the shape of a circle with a radius of 3.5 mm.
My objectives are as follows:
Achieve a uniform illumination of the circle (...
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What is the ideal theoretical construction for an insulative box to keep my frosty beverages frosty?
What is the ideal construction for an insulative box to keep my frosty beverages frosty? I am interested in finding the theoretical maximum as well as the practical maximum.
I was sitting on my back ...
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How to correctly use the thermal conductivity coefficient formula?
I'm trying to help a friend.
We are trying to use the formula below to calculate the thermal conductivity coefficient of a composite material (styro-bamboo).
Q=100 Watts, d (or thickness)= 20mm, A= ...
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How to calculate the thermal conductivity of a composite material
Very new to thermal conductivity calculations, so I'm aware there are already queries on here that may cover this, but I'm struggling to apply them to this instance.
I'm trying to calculate the U-...
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U-value for suspended ground floor
I'm about to finish U-value calculation for a house (an assignment for the Sustainable Technology for Buildings module) but I can't understand the formula. I've got all the data except from "ln&...
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approximate equation for temperature drop near wall in contact with fluid
I am concerned about the following problem and so far I am not able to find a solution. Let us consider an environment at a temperature $T_a$ and the inner surface of a not insulating wall in contact ...
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heat flow in a annular cylinder of insulating material
Maybe this belongs in DIY, because ... I'm trying to analyze the amount of heat required to prevent water supply pipes from freezing. The pipes would be protected by electrical heating tape and ...
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Why Ball-Grid Arrays are More Heat Resistant
I read that for Ball-Grid Arrays, the BGA's act like a thermal dissipator because there are more channels, so it is more heat resistant as opposed to Thin-Quad Flat Pack which uses pins.
Is this ...
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Calculating Glass Wool Insulation Thickness
I intend to calculate required thickness of glass wool insulation for a hot vessel. I know the temperature inside the vessel, the acceptable temperature at the surface of the vessel (after insulation),...
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Modeling 1D Transient Heat Transfer: Wall/Room interface
Consider a 1D adiabatic room (of volume V) with a wall conducting heat on its left side.
The wall is solid and heat conduction in it is driven by the common heat equation.
There is convection at the ...
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High thermal conductivity in soft, fleece-like textiles
Fleeces typically exhibit low thermal conductivity, and are often used in winter clothing for their insulating properties.
I am seeking a material for a radiant heat application that is soft to the ...
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Human lying on a cooled mat - ballpark estimate of heat transfer rate
Hardware builder and youtuber Naomi Wu came up with this idea to help people with acute heat stress due to very hot and possibly moist weather: Instead of cooling all the air in a room, just place the ...
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Heat transfer: does the heat generated in a cable get transferred to the electrical components?
I have a 1000 V, 50 sq mm, double insulated (XLPE) copper conductor cable. This cable is being connected to a power electronic component.
The current flowing through it is 230 Amps DC. The cable ...
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What is the thermal conducivity of Air between two plates?
What is a rough cut figure I could use to determine what the thermal conductivity of 10mil and/or 20mil of air sandwiched between two plates (perfectly conducting)?
I understand that convection dies ...
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Why heat transfer happens only via conduction in this case?
Why heat transfer between a heated flat plate and a fluid happens via conduction only and not convection, when the fluid is present below it?
Consider a plate under which a fluid is present and it ...
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Calculate Thermal Conductivity of Layered Structure
I am having a problem determining the thermal conductivity of a layered sample. The sample is made of two materials, one whose thermal conductivity is known (λ-1) and one whose thermal conductivity is ...
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Does forced convection account for energy transfer in this case?
I have to confess that thermodynamics is not a friend of mine.
My system consists of a volatile droplet sitting on a thermally conductive substrate. The energy balance comprises heat lost due to ...
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Heat Diffusion and Specific heat
Consider two slabs - Slab A and Slab B, insulated on "latereal" faces as shown, initially at the same temperature, and having identical dimensions. The slabs at t= 0 are brought in contact ...
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Why different characteristic dimension for Biot Number and Fourier Number?
In unsteady heat conduction analysis,
Biot Number and Fourier Number are given as follows:
$$Bi=\frac{h L_c}{K}$$
$$Fo=\frac{\alpha t}{L_c^2}$$
where $L_c$ is the characteristic dimension or length
...
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Isn't the Newton's cooling law for heat convection too macroscopic for CFD simulations?
In CFD (Computational Fluid Dynamics) simulations, the space is discretised into a huge number of tiny cells and, therefore, one has the opportunity to use a model of heat transfer that takes into ...
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Critical Radius of Insulation
Consider a long pipe inside which a hot fluid flows. The pipe is exposed to ambient air which is at at some temperature $T_\infty$. Let the inner radius of the pipe is $r_1$ and the outer radius is $...
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Why does the author assume the temperature to remain constant, in this case, along the axial direction?
This is in regards to steady heat conduction taking place in a pipe.
Within the pipe a hot fluid flows and heat transfer first takes place via convection to the pipe and then via conduction within ...
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What causes the temperature to drop at the interface when two slabs are brought in contact?
Consider two slabs made up of different materials which are brought in contact with each other as shown. Thermal energy is supplied from the left, and it flows through the two slabs towards right.
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Time required for balls to cool down
Two balls A and B, made of different materials, having the same radius, are initially heated to the same temperature $T_i$ and then are kept in the same environment which is at a temperature $T_\infty$...
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Thermal Conductivity and Energy gain
I have a two part question:
Part 1:
I understand thermal conductivity as
The measure of a material's ability to allow thermal energy transfer to it, from it and within it via conduction
My very first ...
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What and why thermal diffusivity?
I understand the following properties:
Thermal Conductivity: It tells how well thermal energy can get transferred to a material, from a material and within the material. A material with higher thermal ...
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Best metal for solar energy collection in an evacuated tube solar water heater
I am building an evacuated tube array for a solar water heater and I am selecting the materials to use for the tubing and the collectors (the places connected to the tubing that help absorb the solar ...
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Examples of two dimensional heat conduction problems
Can anyone give me some examples from real life, where the heat transfer can be modelled as two dimensional. Also if one could explain why we can model it as 2 dimensional.
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Question regarding evaluating 1D heat transfer PDE
My question regards cooling of an object using 1D-heat transfer with fixed surface temperatures. First I need to find the solution to this PDE:
Based on the conditions, I worked out that the ...
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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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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 ...
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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 ...
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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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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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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 ...
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