Engineering Stack Exchange
Engineering Stack Exchange

Questions tagged [heat-transfer]

Questions relating to the transfer of heat via the mechanism of convection, conduction, or radiation, in forms of systems (or your device) attempting to obtain thermodynamic equilibrium with another system (the environment or your other device)

532 questions
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Heat pipes vs fluid cooling

I was wondering about the main difference between using heat pipes and a fluid-based cooling system. In both cases the heat is transported away from the heat-generating area to a place where the heat is dissipated. What is now the advantage of using…
arc_lupus
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Estimating the time required to heat a rod by a certain $\Delta T$

Consider 1D heat conduction on a rod of length L. Assume the rod has a known density $\rho$, specific heat $c_p$ , and thermal conductivity $k$, all of which are constant with respect to temperature. Suppose that the initial temperature of the rod…
Paul
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Calculate thermal flow for air flowing through a tube, with fins

I have the same problem as described in this question: How to calculate the resulting temperature for a stream of air through a hot tube?, but I want to increase the transferred heat by adding fins onto the inner side of the tube, parallel to the…
arc_lupus
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Nusselt number for partially adiabatic tubes / rectangular ducts

I am trying to model laminar, forced convection heat exchange for water in a round pipe and rectangular duct. In both cases, a portion of tube / duct is maintained at a constant surface temperature while the rest of the tube / duct is insulated. I…
user69813
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Will a shade hood increase a/c efficiency?

Would adding a shade (i.e. a piece of plastic) at the back of an A/C increase the efficiency of a window unit A/C? I'm not talking about covering the fins but rather placing a sheet of plastic above to create shade without obstructing the air flow.…
Ruminator
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How to calculate the resulting temperature for a stream of air through a hot tube?

Given the temperature $T_1$ and volume flow rate $\dot{V}$ at the start of the tube, which has a temperature of $T_0$ and an inner surface of $A_0$, what is the resulting temperature of the stream going out of the tube? ($T_2$). I assumed that the…
JHK
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Cast iron sewer pipe being used as stove pipe

There is a house for rent with a big barrel stove in the basement, the stove pipe is insulated where it comes through the floor however it is made of old sewer pipe, cast iron I imagine, it's about a 15-ft section, this doesn't seem like a good idea…
Heidi Kulcheski
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Calculate heat transfer for a partly hollow cylinder?

What is the general approach for calculating the heat transfer through a body? In this special case I want to calculate the $\Delta T$ (i.e. the temperature difference between the side and the top/bottom) for a given $P_{heat}$ through the following…
arc_lupus
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Convert 1 one compound unit to another involving temperature

So, I must do the following conversion from my engineering textbook: $0.155 \frac{m^2 * ^{\circ} C}{W}$ to $\frac{^{\circ}F * ft^2 * hr}{Btu}$ I can get as far as: $0.155 \frac{m^2 * ^{\circ} C}{W} * (\frac{1 ft}{0.3048 m})^{2} * \frac{1…
FabulousGlobe
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Is there any unilateral heat exchanger?

I don't know if this is even possible or not but are there any pads that can transfer/exchange heat from one side to the other side unilaterally? I mean that the heat could be transferred from one side to the other, but can't do the same in…
Ali Khalili
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Pasta cooking time

How does time needed for cooking pasta (or any other food) change depending on stove power output (for simplicity, let's say flame size)? If it does... And why. Starting with the point that water is boiling and continues in it (thus water…
mattia.b89
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Physical Significance

I've been asked to describe the physical significance of a dimensionless group (Biot Number) . I understand the definition of the group but I am unsure what the term "physical significance" means in the context of engineering. Thanks for helping.
E. Mackel
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Rate of Cooling of a Black "Polymer" Handgun

I need to understand some basic concepts about the cooling characteristics of a black "polymer"-and-zinc-alloy handgun (specifically, this one). If this gun was left on the ground under daytime sunlight, I assume that both the ground and the gun…
protasm
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Percent Increase vs. Factor By Which Something Increases

I would appreciate a quick peer check on the following. I am currently enrolled in a class where, I think, the professor is repeatedly confusing percent increase and factor by which something increases. There is a difference isn't there? I'm not…
Nukesub
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Heat transfer in air gaps between slabs

I am working on the modelling of heat transfer in a storage unit consisting of a number of slabs contained inside a rectangular duct. A hand made sketch of the storage is below, as seen from above. The idea is that the air comes to the slab bank…
Franz Roman
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