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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11 views

Dependence of insulation k-value on density

I was learning about insulation materials. EPS has k-value of 0.036 W/m.K at a density of 15 kg/m3 . With this info, is there a direct way to calculate the K value of EPS if its density is 20 kg/m3? ...
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32 views

As a rugged and waterproof device, how does gopro dissipate heat?

I am new to designing rugged + waterproof products. I am curious about how to dissipate heat when the electronics are running and the ambient environment is even hotter. It seems like the mode of heat ...
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18 views

If you have a small fan that blows hot air, and a larger fan that blows cold air against it, what happens to the hot air?

For context, I have a laptop that has a fan that sucks in cold air from the top on the left side (for cooling the cpu), and a fan that blows hot air out the bottom on the right side (for cooling the ...
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92 views

Water Cooling a Personal Computer

I intend to water cool my next PC. There are three areas of heat production in a PC - the CPU, the GPU and the motherboard itself. Would it be more effective to treat these three areas separately (...
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simulate a temperature in tank

there's a website to size an aquarium heater or chiller. This is just for learning purposes (not for fish) but I have modified these parameters from default to perform a load calculation on a 100 ...
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33 views

Can wet welding be done in mineral oil?

I'm interested in knowing whether or not submerged welding can be done in fluids other than water, specifically mineral oil in this case. The reason I want to know is that I'm looking into designing ...
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32 views

When is a heat exchanger worth it?

I am currently working on a huge industrial process for a student project and we need to transfer around 25MW of energy between dozens and dozens of streams, some larger and some smaller ones. Many ...
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55 views

Most efficient orientation of exhaust vents on top plate of chassis for air flow with regard to heatsink fins?

I'm looking for some advice from an ME or anyone who understands heat transfer,convection, etc. I'm currently laying out in Inkscape a top panel for an audio amplifier I'm building. Now, my question ...
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Heat loss calculation and Energy Balance

The image shows the CAD model of the annealing zone in a galvanization simulator. The zone is electrically heated with a AC current of 5597A at 2.09V. This whole zone is surrounded by insulating ...
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One dimensional U-Factor Calculation - How to determine indoor / outdoor film resistances

Can someone clarify the ASHRAE Fundamental 2017 (SI Units) (See Below) Indoor and Outdoor film resistances. The manual states that it comes from Table 3 and in the description of table 3 it states &...
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Diffusion Pump Copper Cooling Coil Repair

I bought a Varian VHS-4 oil diffusion pump off of ebay about a year ago. The pump was stored outside by the people I bought it from so it suffered mostly cosmetic issues. Recently I have acquired all ...
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Determining the heat capacity of an X-Band transmitter

I am conducting a thermal analysis of an X-Band transmitter that will form part of the payload in a CubeSat. The goal is to determine how long the X-Band transmitter can operate before it will ...
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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 ...
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36 views

Simulation of temperature in insulated box

I have a box outside that I want to insulate such that the temperature inside the box doesn't drop below 10°C given outside temperatures of (in the most extreme case - at night) -10°C. Inside the box ...
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49 views

How to calculate heat and mass transfer rates from an enclosed box?

I'd like to know if it's possible to calculate the heat and mass transfer rates from a small volume to the environment. Let's assume there is a box with a small opening at the top. The air inside the ...
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28 views

Safe temperature thresholds for #2 HDPE and #5 PP plastic

It would be convenient to use a temperature adjustable heat plate (element)/mug warmer for the massive amount of blender bottles accumulated over the years. What are safe thresholds to safely warm ...
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Adding a black plastic layer to increase retained heat in compost

I have some invasive climbing weeds to break down into compost. I don't want to discard the biomass, but I do want to thoroughly kill all the weeds and ideally the seeds over a period of months. The ...
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1answer
27 views

Effects of Solar Shield on Electronics Enclosure

I am designing a prototype of an electronics package that will sit out on a pole in the sun 24/7 with a max ambient temperature of 50˚C and at 30˚N latitude. It produces 50W of internal heat ...
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49 views

How can I calculate the airflow needed for a fan to cool a system?

The airflow needed for a system to sustain itself at 80°C with 25°C ambient temperature can be calculated with this formula: ...
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64 views

How effectively will this evaporation setup cool down the water?

I devised a setup, and I show it in the diagram below. Suppose I have these specifications: Water in the bottle is 5 liters and it's initial temperature is 28°C. The bottle capacity is 6 liters. The ...
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35 views

When does Q = m(h2 - h1) hold true?

From the first law of thermodynamics: $$\Delta U = Q_{12} - W_{12}$$ where $\Delta U = m(u_2-u_1)$, $W = p(V_2 - V_1)$ with constant pressure, and $Q = m(h_2-h_1)$. In the energy rate form of the ...
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328 views

Why Nusselt number for laminar flow in a pipe is independent of reynolds number

I understand that for fully developed flow inside a tube (with constant properties), Nusselt number doesn’t change in axial direction but it is surprising that it is also independent of Reynolds ...
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113 views

In a diesel engine, does more heat leave the engine through the tailpipe or the radiator?

Diesel exhaust is hot, and there's a lot of it. Diesel radiators also get pretty hot. In a typical diesel engine, which one is dissipating more heat? EDIT: In response to a request for specificity ...
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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 ...
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1answer
18 views

Why do plate exchangers typically serve lower pressure fluids than shell and tube heat exchanger?

According to Wikipedia http://en.wikipedia.org/wiki/Heat_exchanger, plate exchangers typically serves lower pressure fluids than shell and tube heat exchanger, why? Tubes in plate exchangers are ...
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1answer
9 views

Melt plastic powder bed with radiant heat?

I want to melt a bed of plastic powder so that the powder bed once melted and then cooled forms a solid sheet of plastic. In order to melt the powder I'm thinking of passing a nichrome (Ni80/Cr20) ...
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64 views

How does the Xbox Series X “Heat-sink chassis” work?

I understand what a heatsink does, but I cannot wrap my head around how the newly announced Xbox Series X's heat-sink chassis works. From Xbox: Heat-sink chassis A heat sink is a non-electronic, ...
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92 views

What are these outdoors “mystery boxes” for in the USA?

While watching random videos shot in the USA (in the present time), I've noticed these little weird outdoors boxes: What is the purpose of these? They look like they might be related to ventilation ...
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18 views

Simulating heat conduction on a 1-D Fin

I am trying to simulate the heat conduction on a 1-D fin. The problem I am having is that I do not know how to properly calculate the temperature in the last point of my 1-D grid. We were asked not to ...
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60 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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1answer
23 views

Heat Loss through a run of insulated piping

I've been racking my head around calculating the amount of heat loss still water will experience through a run of insulated piping. The water in the tank is maintained at roughly 550°F saturated, and ...
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54 views

How can water mist lower a room's temperature?

Let me start off by saying that this is strictly NOT a homework question, so before you mark it as "homework", think. I was looking at how the water cools my body when it evaporates off it. Then I ...
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36 views

Calculation for lowering temperature in a room… room-fridge with water mist?

I was looking at how the water cools my body when it evaporates off it. Then I thought the specific heat capacity could be used to calculate how much energy (i.e heat) would be taken out of a room ...
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31 views

How to periodically shut down a recirculating hot water solar thermal system

I am posed with a scenario where a hot water solar thermal system has been setup. The system comprises of a cold water tank, heating arrays and then a hot water tank. The system is closed loop and ...
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Comments on Patankar's book Numerical heat transfer and fluid flow

How to make comments on the book of Patankar, titled 'f' in 1980? Is it really worthy for beginners in the field of numerical heat transfer to read it? Besides, after finishing reading this book, what ...
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1answer
22 views

How to consider the dimension of a cylinder when computing its radiative budget?

I am trying to derive a heat budget model to estimate the temprature of very small a stationary vertical cylinder (1mm) under environmental conditions. Imagine a wooden stick. Simply put, I have R = ...
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39 views

How do you calculate heat transfer due to solar radiation for a multi-layer wall given the incident solar radiation and wall specs?

Trying to come up with a MATLAB code for calculation of heat transfer due to incident radiation on a building's walls, would the solution involve using the conduction equation only? What would be the ...
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1answer
45 views

Stirling Engine Cooled Engine

Could a Stirling Engine replace the cooling system of an engine? Instead of having a clutch and fan attached to the main drive shaft to cool an engine, could a Stirling Engine and clutch share that ...
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2answers
41 views

Wall Humidity Condensation

Imagine you are in the mountains and it is very cold. The walls are colder than the air, so air close to the wall will lose heat to the wall, and by losing heat it might lose its humidity (water ...
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Oil pressure inside copper tube?

**Background ** I'm struggling finding how to calculate the pressure that occurs within my system and then once calculated I need to reduce that pressure. My system I have a 1 inch copper pipe ...
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123 views

Can a Peltier's device (i.e.Thermoelectric cooler) achieve cryogenic temperature efficiently?

Does the stacking of peltiers device shows promising results in achieving the cryogenic temperature? I have tried doing the experiment, the overall temperature of the system increased around 80ºC and ...
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44 views

Method for comparing efficiency of heater block designs?

How would I go about comparing the efficiency of different heater block shapes for the outlined system? So, in the attached diagram there is a cylindrical heater cartridge (A) that is used to ...
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35 views

What is the average energy loss due to rolling friction in contemporary motor vehicles?

Around what percent of energy provided by gasoline is lost as heat due to rolling friction in vehicles? Is this number higher for larger vehicles likes trucks than smaller vehicles like bikes? ...
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69 views

Does a house heating system affect perceived and true indoor air humidity?

Does a house heating system affect indoor air humidity? Or to be more precise, does it affect your perception of how dry the air in the house feels (for instance dry is your mouth waking up)? (I ...
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30 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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44 views

Temperature rise of a block of aluminum under constant heat flux

Consider a block of Al. insulated all around except on one side, where a heat-pipe is to be inserted. On the opposite side of the heat-pipe, there's a heat source (Resistor) with a given heat flux. ...
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17 views

Transient Heat Transfer Problem for a parabolic PDE of Rectangular Plate

I was able to write the elliptic PDE for the steady-state temperature of the plate but I am having a very hard time doing the same for the transient problem. Now consider the transient problem for ...
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42 views

Placement of supporting boiler in heating circuit

In my thesis, I deal with heating circuits, where several heat generators are present, e.g. a combined heat and power unit and a supporting boiler. Usually, the boiler is placed in front of the heat ...
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How can we dissipate the heat from a block of 10*10*3 mm with 100 degree Celsius without losing the portability of the block?

I have a Peltier's device of 10*10*3mm and the material is Bismuth Telluride. The hot side is 100 $^oC$ and I want to dissipate the heat, and at the same time, the device should be portable i.e. it ...
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105 views

Heat transfer coefficient of a cylindrical hot water storage tank depending on its size

I have a simulation model of a cylindrical hot water storage tank. The heat loss is determined by the surface area and the heat transfer coefficient. A configuration of the storage tank with 900 ...

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