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)

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thermal resistance and thermal time constant with ambient temperature

If water at the same temperature is heated with the same heat power source in two different ambient temperatures (one ambient is low and the other ambient is high) then which water sample will reach ...
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503 views

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 ...
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1answer
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Modeling Transient Heat Transfer between two 1-D materials

I have been working on creating a 1-D model of a material with a layer of heat resistant material stuck to it. For this I have been trying to use the implicit finite-differential method. The equations ...
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0answers
130 views

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/...
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1answer
440 views

What are heat sink options for a circulating-water cooling vest?

I am in a first-year engineering design group where we are in the process of designing a cooling vest for motorcyclists for use in the city (1-2h length). Water will circulate through the vest, ...
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1answer
700 views

"Transport Phenomena" (Bird, Stewart, Lightfoot) difference between edition 1 and 2 [closed]

What is the difference between Transport Phenomena first edition (1979) and second edition (2002)? Which one do you recommend to be bought, taking into account that I am a student and that the first ...
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2answers
642 views

External diffusion: calculation of surface concentration

I am struggling a bit with an external diffusion problem. I am trying to calculate the concentration at the surface (as well as surface reaction rate) and would like some help or guidance. Here is ...
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1answer
314 views

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}{...
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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 ...
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203 views

Mathematical relation between shear stress and temperature

I have recently started research in mechanical engineering. Currently I am working in the field of friction stir welding. During my study I came across a point where I have to find the mathematical ...
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1answer
535 views

Hydraulic switch vs heat exchanger

In a heating circuit, there's two (known to me) ways to decouple primary flow (through heat source) and the secondary flows (to consumers): a hydraulic switch in the heating manifold complete ...
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Advice on Literature pertaining to transient pipe flow with heat transfer and friction [closed]

For a project I am working on I need to model the flow of argon in a long pipe. The flow is transient in nature since the tanks and regulator from which it enters cause the mass flow to change. ...
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1answer
112 views

Mounting heat source onto heat pipes [closed]

I want to mount a heat source onto several heat pipes. The heat will be forwarded to coolers (four heat pipes, 200 mm) which are able to distribute up to 120 W without increasing the temperature of ...
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2answers
234 views

Can pressure rise due to heat flux in a pipe?

I'm talking about a: smooth circular pipe without any valve at inlet or outlet without pressure losses due to friction subjected to a constant heat flux from outside on the entire pipe ...
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1answer
164 views

How to minimize heat loss in an air extractor?

In an air-conditioned house equipped with an air extractor that removes for instance wet, smelly, etc. air from the bathrooms and kitchen, what are sensible cost-effective systems to prevent: Heat ...
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1answer
411 views

Which correlation for heat exchange in a partially adiabatic channel?

I'm modelling a heat exchanger inside a channel. Talking about convective one: Geometry is simple, square of 1.5 cm but only one side exchanges heat. The "problem" is that only one side exchanges ...
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1answer
8k views

Log Mean Temperature Difference of a Counterflow Heat Exchanger

I am solving the following problem: A liquid-to-liquid counterflow heat exchanger is used to heat a cold fluid from 120 °F to 310 °F. Assuming that the hot fluid enters at 500 °F and leaves at 400 °...
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1answer
969 views

Heat Loss per Linear Ft

For an assignment, I was given: Calculate the heat loss per linear ft from $2$ $in$ nominal pipe. ($2.375$ $in$ outside diameter covered with $1$ $in$ of an insulating material having an average ...
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2answers
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Problem with Energy Transfer Rate Conversion

Given the question: Calculate the energy transfer rate across a 6 in wall of firebrick with a temperature difference across the wall of 50 °C. The thermal conductivity of the firebrick is $0.65\...
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1answer
6k views

Calculating the temperature of the lagging around an insulated pipe

I am solving the following problem: A Pipe 200 mm outside diameter and 20 m length is covered with a layer of 70 mm thick insulation having thermal conductivity of 0.05 W/m·K and a thermal ...
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1answer
133 views

Should the temperature of a heated metal cone decrease in a plastic enclosure?

Summary A steel cone is heated by a nichrome ribbon to 45–50 °C. I placed a Type K thermocouple over the surface of the metal to measure the heat transferred over the metal surface. The thermocouple ...
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1answer
2k views

The Heat Added in a Reversible Polytropic Process

The question: Consider $1\ kg$ of air at $32\ C$ that is expanded by a reversible polytropic process with $n=1.25$ until the pressure is halved. Determine the heat transfer. Specific heat constant ...
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4answers
236 views

Convective fix for air conditioning dilemma?

I live in a part of Mexico that can get really hot in the summer. I've got an un-airconditioned bedroom on the other side of a wall from a room cooled by a powerful Mirage mini-split AC. The problem ...
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4answers
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Can air conditioners/dehumidifiers exhaust their waste heat in their exhaust water?

If I understand correctly, both air conditioners and dehumidifiers conventionally exhaust waste heat through their exhaust air, though both also produce exhaust water. I'd like to know, Are air ...
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0answers
176 views

Thermal transfer function of an isotropic material

Consider a piece of material of infinite extent (i.e. no boundaries) with a point source of heat at its center which oscillates at frequency $\omega$ about the mean temperature $\langle T\rangle$. If ...
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1answer
2k views

Where to place fans for maximum effectiveness in sharing air conditioning between rooms?

I have a split-type inverter air conditioning unit in one room placed near the ceiling. Assume that the cooling capacity is met, and I'm using the correct CFM of fans. I would like to share this air ...
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1answer
8k views

Heating the air in a small box

Background I am working on a project that involves heating air inside a small box, then measuring the temperature over time. The purpose of the box is to be a basic test chamber for PID experiments. ...
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1answer
2k views

How to calculate heat generation on 2D plate?

I have a 2D plate with heat source at one part and I need to calculate the heat generation. The plate is made of aluminum (k = 212 W/m°C). I have watched this example video, but I'm not sure if I can ...
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1answer
179 views

Determining behavior of heat exchange system

I'm trying to develop a thermoelectric (Peltier tile-based) beverage cooling system. Ideally, I'd also like a device to solve the warm beer problem if the thermodynamics give me any confidence. First,...
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1answer
1k views

How does a microbolometer (IR camera) work?

I am currently doing a project which has led me to my first encounter with IR cameras, and I am therefore quite curious as to how they operate. Specifically, I would like to know the following How is ...
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1answer
108 views

Material which can be used for resistive heating and simultaneous temperature measurement

I want to embed a wire inside a plastic and heat it to specific temperatures (80$^\circ$C 100$^\circ$C 130$^\circ$C 180$^\circ$C). I want to find a material that is resistive enough for resistive ...
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1answer
167 views

What coefficients should I use when modeling non-stationary heating of a steel plate?

I am trying to make a model of non-stationary heating on a plate, where I must use an explicit numerical method to solve the model. I decided the plate will be made of steel (0,5% C) and I found that ...
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2answers
461 views

What relationship is there between mass of water vapour produced in combustion and the energy lost through producing this water?

I am performing a number of simple heat transfer experiments with the application of a magnetic field around the fuel line to evaluate the effects. To attempt to quantify some of the heat losses in ...
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5answers
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What is the Best Heat Resistant Translucent Material?

I am looking for a material that can be used in a non commercial environment that will allow all (or nearly all) light to penetrate but will be heat resistant (By heat resistant I mean it will not ...
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1answer
2k views

Do magnetic fields applied to a fuel line have an effect on heat output?

I am doing my final year engineering project on Magnetic Field Assisted Combustion and was curious to see what people thought about it. Companies sell rare earth magnetic arrangements to be attached ...
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2answers
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How can I calculate the temperature rise of a circuit board for a given power dissipation and area?

I have a PCB of approximately 4" x 4". It has a single long spiraling trace on it. The trace is 50 mil 4 oz copper, so nominally it's good for something like twenty amps before it overheats. But this ...
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5answers
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How can one calculate the change in heat energy when the specific heat varies with temperature?

Many materials have a specific heat which varies with temperature, especially as the temperature change grows large. How does one calculate the heat energy that an object receives in this case? Can ...
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1answer
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How to calculate indoor temperature?

I am trying to calculate the effect of insulation and weather conditions on a cottage. The cottage is made from a timber frame while the panels are of 4mm plywood. The weather conditions vary ...
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2answers
763 views

Comparing the performance of glass and granite in a heat storage application

Background I am working with a small team on a university project to build a greenhouse heat sink. This will pass warm air at the top of the greenhouse down through a chamber underground filled with a ...
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2answers
526 views

Evaluating performance of heat sink designs without finite element simulation

I have the opportunity to do a few metal 3D prints for just the material cost, and would like to experiment with the performance of heat sink designs (mostly for fun). Since I have no experience ...
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6answers
4k views

How to remove heat from an IP66 enclosure?

I have a small IP66 polycarbonate enclosure with a Zirconia-based oxygen sensor which produces significant amounts of heat (the internal sense element runs at 450C using a 1.5W heating element, sensor ...
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2answers
2k views

How are the thermodynamics of CPUs and other chips handled?

I hear that designing the thermal efficiency of such systems is very difficult. I'm not sure why, though, and I am interested. On the one hand, I bet the heat is somehow a function of the total power ...
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2answers
3k views

How do I determine the thermal resistance of a metal box?

Suppose I have a sealed enclosure, say this one from Hoffman: The box is 16"x12"x6", made of galvanized steel with a wall thickness of .0635" or .0785" (gauge 16 or 14). I'm planning to put some ...
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2answers
2k views

Optimizing return temperature in a brazed plate heat exchanger

I have a brazed plate heat exchanger similar to these. I can regulate flow and temperature of water on the primary side of the exchanger to achieve the desired temperature of water on secondary side. ...
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1answer
173 views

Scale models of thermal plumes

I want to look at the thermal heat plume of a human in still air in a room. So I have a tank of water with a heating coil/cylinder in it. How do I calculate what the heat output of my heating coil ...
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1answer
2k views

How to design a house to be cooled passively? [duplicate]

I live in Louisiana these days, in an area that is known for its numerous antebellum plantation homes (circa early 1800s). While touring one of these homes it was clear that almost everything about ...

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