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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Whats the advantage of variable speed furnace blowers?
I'm in the market for a new heating and air conditioning unit for my home. Most offer variable speed blowers and the more expensive models are equipped with BLDC motors, which seem overkill. I am ...
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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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Will the COP of 10 stage cascaded refrigeration / AC system be high?
Consider a cascaded refrigeration/AC system that has ten stages, with each stage cooling by only 5°C/9°F. For example: Cooling takes place from 40°C to -10°C over ten stages. Each stage has a high ...
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Implementing convective boundary conditions for 1-dimensional finite difference computation of heat equation
I am simulating heat transfer through a 1-dimensional wall with convection on both sides. For the wall, I implemented a finite difference model like this:
$$
u(x, t + ∆t) ≈ u(x, t) + c [u(x + ∆x, t) − ...
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Method to estimate indoor temperature from heat inputs, rather than A/C power from target indoor temperature
I'm looking to estimate the temperature drop I could expect in my house by installing cool roof tiles. The house does not has a regular air conditioning system.
I have delved into HVAC references but ...
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Heat losses of warm fluid in a cold pipe
I'm looking for a way to calculate/estimate heat loss in a fluid flowing trough a pipe for a length (l) and travel time for the fluid (t). The flow is intermittent and the initial pipe temperature (...
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Plane strain delamination on bilayer material (conversion from material stress state to residual force and moment)
I have been reading the book The Mechanics and Reliability of Films, Multilayers and Coatings (https://doi.org/10.1017/9781316443606) on chapter 4.2 and got stuck in chapter 4.2 and 4.3.
Suppose that ...
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Any real heat engines based on the Carnot cycle? (or an equally efficient cycle)
Most practical heat engines are based on ideal cycles whose processes are different from the Carnot cycle (eg; constant pressure or constant volume heat addition instead of isothermal). I understand ...
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Understanding chiller performance curves
Recently I was tasked with some chiller-related tasks and I need to understand the performance model. More specifically, I am interested in the EIR EnergyPlus chiller model.
The chiller's performance ...
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Optimal blade/paddle design for low-budget Friction Heater (Joule Machine)
Generating heat by stirring fluids
I am interested in the direct conversion of mechanical energy into thermal energy as it was done by James Prescott Joule. For context: I was inspired by the danish ...
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What amount of heat can aluminium box sustain?
So I want to install electronics inside 120 L aluminium box. The electronics have losses, which result in 50 - 150 watts heat. Can such size box contain these electronics without rising temperature ...
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how do i calculate the heat recovery and outlet temperatures of a heat exchanger only knowing exchanger size and inlet fluid conditions?
all of the heat exchanger calculations i can find assume you are trying to design a heat exchanger to get your required temperature at the outlet or a specific Btu recovery. my issue is that i have a ...
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Determine the temperature required for expanding or bending?
Is there any possible way to calculate the temperature required for a metal to expand or bend with dimensions?
For example, take Mild steel with a length of 100mm, width of 150mm, and thickness of 2....
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Contactless heating of levitated tungsten
I want to make a setup to melt tungsten. The best method I've come up with is using an induction heater to levitate and heat the tungsten, in a vacuum to prevent oxidation and limit heat transfer.
I'...
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Can a horizontal ground collector heat pump be installed on a 30% slope?
I'm considering what type of heat pump (air-to-water or ground-to-water) to install for a house in hilly terrain in Central Germany, to replace an old oil heater from the 1990s. The house has a 750 m²...
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Calculating time to heat up a flowing fluid. Units not matching up
I have an electric heater that can output 915.4 kW of power. I have fluid (isobutane) flowing through the heater around 1 kg/sec. The starting temp is 172.5 °C and the required temp is 343 °C. The ...
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When was the phrase "lumped thermal capacitance" first coined?
As per the title, when was the phrase "lumped thermal capacitance" to describe a particular way of analysing multi-component heat transfer and energy storage systems first coined, please? I ...
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Finding Intermediate Temperatures of 2-Stage Counter Current Heat Exchanger
I have a 2-stage counter current heat exchanger where I am given the initial temperatures for the cold and hot fluids (TH1 and TC1) as well as the final temperatures (TH3 and TC3). Additionally, The ...
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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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I want to transfer heat from a solar concentrator to be stored in a sand battery , which heat transfer fluid is more viable , cheap and easy to use?
I am searching about connecting a solar concentrating system to a sand battery so I need a viable ,cheap and practical heat transfer fluid to distribute and store solar heat into the sand layers up to ...
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Advice needed on how to cool 50 ml liquid from 60 °C to 30 °C
In Short: I'm working on a project where we need to cool 50 ml of liquid from 60 °C to 30 °C or 20 °C. The liquid will be in a 150 ml copper container with an open top.
Due to the lack of skills in ...
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Does 'Jet Impingement Cooling' always cool?
I understand that by using jet impingement cooling, we can achieve a high convective heat transfer rate, but there is also a stagnation region where the kinetic energy of the jet will be converted to ...
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Why is there a MIN and MAX marking on a car coolant bottle?
This question was initially posted in physics stack exchange, then the mechanics stack exchange but I think it's more appropriate for engineering section instead.
I've always thought the minimum and ...
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How can you determine the heat transfer area of a plate heat exchanger
Given the number of plates and channels (1-number of plates), as well as the width and length of each plate, it is true that the heat transfer area can be calculate by:
A = wL number_of_channels
Is ...
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Pin Forest Heat Sink Design and Optimization
I am trying to design a heat sink as part of a broader system and determine two things:
Given the size constraints of the system, commercially available fans, and heat dissipation requirements, is it ...
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How hot can heat pump boilers feasibly go?
Over on Worldbuilding, someone sorely wanted a battery-electric steam locomotive. Doing that with resistive heating is a non-starter because of the heinously poor efficiency of the traditional single-...
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Efficiency difference of an evaporative air cooler based on its dimensions (wider or taller) given that all the other aspects are same
I own an evaporative air cooler of width 28 inches and height 34 inches, I was wondering if a taller air cooler with lesser width (but same surface area as the one I own) would have been more ...
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Trying to calculate heat transfer into an insulated rectangular box in the sun
I am trying to calculate the BTU/hr of cooling needed for an RV. I am willing to assume it is an 8'x16'x8' box with no windows with uniform insulation (lets say R15 if it matters) on all surfaces. ...
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Thermal Transfer with Heat Source
Two objects (A & B) are separated by a 1 m long square rod (5 cm x 5 cm). The objects and rod have a thermal conductivity of 130 W/mK. Object A is a heat source of 10 W. Assume there is no ...
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Would injecting water in a turboshaft engine avoid turbine material meltdown?
For the little I know about turbine engines, I know that these run at enormous high temperatures and thus, need nickel based superalloys.
From what I know, jet engines use a smart use of air flow ...
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Cooling capacity of sealed aluminum electronics enclosure
I need to design a sealed electronics enclosure that also functions as a heat sink. The main component I need to cool generates max 15W. This component will directly contact the walls. The remaining ...
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Importance of mass flow rate on the overall heat transfer coefficient
As mass flow rate increases so does the heat coefficient. Is there a way to directly relate this? Is it because of the flow going from laminar to possibly turbulent also help increase heat transfer. ...
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How long a spiral copper tube would need to be in a monotube boiler in order to achieve 0.02 kg of steam per second?
So, I'm trying to calculate how much fuel/energy I would need to input in a homemade monotube steam turbine engine in order to achieve 15hp (11kw), the idea is that the engine will run at this ...
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Heat transfer in open equalization tank
I have to cool waste water in equalization tank (open tank) from 60 C to 30 C.
Here is the information about the waste water:
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/...
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What property cause a stainless steel slower get heated and slower get cooled, compared to aluminum
I did simple observation when I was heating water using stainless steel container and aluminum container. Indeed they are not exactly same but quite comparable. What I discovered was that, with the ...
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How do I calculate the temperature change inside a box with multiple heat sources?
I have a box (as shown below) with 3 measurement devices in it. They are all the same size and stacked on each other. The power consumption of the devices is 250W, 50W, and 50W. They all have internal ...
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Heat extraction in Nuclear Fusion
In nuclear fusion the atoms are in a hot plasma and the temperature is >5000K for them to posses kinetic energy and overcome repulsion to fuse , this process generates some heat(which is equal to ...
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Thermal performance
Which is higher thermal performance: R15 effective wall calculated per ASHRAE90.1-16 or an R15 effective wall calculated per the Thermal Bridging Guidelines?
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Correlations for convection coefficients in tubes at high Reynolds numbers
I am looking for a correlation to calculate the heat transfer coefficient for a convection problem for turbulent flow in a tube at high Reynolds numbers of > 5×106. This is where the Gnielinski ...
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Can a steel plate reach -20°C due to radiative cooling when the ambient temperature is 2°C?
Conditions: there is a steel plate insulated at the bottom and facing the clear night sky, the ambient air temperature is 2°C, the cosmic microwave background radiation is 3K, and the convective heat ...
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Analytical or approximate formula for temperature distribution in a greenhouse
Here is my problem: Imagine an hemicylindrical greenhouse, with length $L >> R$, its radius. So we consider it as a 2D problem.
According to the schematic we have the flux of the sun at the $\...
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How can I create a constant temperatur-Load in Abaqus?
Im working of a model of a clamped steel hollow section column, which is stressed by a local fire. I would like to map the case of fire by area with a constant temperature. For this I have set the ...
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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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How do heat pumps output more heat kW than the electrical kW used to run the heat pump?
I understand that a 2 kW electric heater will use 2 kW of electricity and output 2 kW of heat (apart from small losses of energy as infra red, vibration etc.. but let's exclude those for this example ...
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Ultra-high temperature heat pump possibilities
How can I best transfer heat from space A [200ºC, 200 bar] to space B [1060ºC, 200 bar] using a heat pump style method? Both spaces are air filled.
Keeping in mind typical material limitations, a ...
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Optimal maintenance temperature and allowable drop for energy efficient hot water storage
I bought an under-sink electric boiler/hot water storage unit, for instant almost-boiling water. This device has an 'eco' mode, which broadens its hysteresis to 10 degrees C: it will allow the stored ...
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How do I get the temperature of a stainless steel pipe that's being heated by a direct current?
I'm working on the following problem:
Use a stainless-steel pipe with an internal diameter of 0.016m and a length of 2.5 m to conduct a convective heat transfer experiment. During the experiment, the ...
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Do glass windows reflect heat? If so, how to mitigate that?
Saudi Arabia is planning a skyscraper city which is 500 m tall, 200 m wide, and 170 km long. It'll have an all-glass facade. So, a concern is that the glass will reflect the heat until the ...
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Heat insulation thickness needed for a truck box conversion
I'm starting to work on a project of converting a truck box to a motor-home,
and one of the key components for me is heat insulation.
I'm from a sunny country with temperatures that in summer can go ...
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Recent breakthrough on Inertial Confinement Nuclear Fusion at NIF
For the very first time, it has been demonstrated that it is now possible to make Nuclear Fusion generate more energy than is required for its equipment to operate, but it is not entirely clear as to ...
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