# 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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### Does fog affect the efficiency of heat pumps?

Aggregate changes require way more energy than temperature changes. I vaguely remember that it takes about the same engergy to get water from 5°C to 80°C as getting ice to 1°C warm water. Hence my ...
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### Quantitative Risk Assessment Of Onshore Crude Oil Pipelines

I am currently working on a project that requires a quantitative risk assessment of a potential release (analysis of frequency and consequences) onshore pipelines transporting crude oil (underground). ...
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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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### What effect does airflow rate have on heat dissipation if the initial heat varies proportionally to the airflow rate?

If I have a server rack consuming 10 kW of power in an empty room with A/C, what effect does the rate of airflow from the rack's exhaust have on the temperature in the room and the load on the HVAC? I ...
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### Calculating heat loss of water in a tube

I am seeking to understand the logic and math related to the calculation of heat loss of water in an insulated tube. My goal is to determine what inlet water temperature is required to avoid the water ...
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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. ...
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### Suggestions for estimating Heat Load (watts) in an evaporator (antifreeze - hot fluid, R744 - cold fluid)

I am working on simulating an evaporator for an R744 refrigeration cycle. Here, I have inlet conditions of R744 with low pressure (around 30 bar) and low temperature(-8°C) and that of antifreeze (35% ...
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### Calculating heat loss over a maple syrup pan evaporator

I am working on a final project for my thermo-fluids design course, and I am designing a maple syrup steam evaporator. The sap enters the evaporator through a 1.2 meter wide channel at ambient ...
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### Trying to find time where an average temp is reached in a cylinder?

My problem consists of a cylinder with 2D heat transfer. In the radial direction the biot number is less than 0.1 so uniform temp distribution is assumed, however in the planar direction it is not. I ...
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### Can cascaded heat exchange system transfer more heat?

Suppose there is hot water supply at fixed flow rate and inlet temperature around 40~60C, also there is cold air to be heated by the water at fixed flow rate and inlet temperature around -10~20C. Heat ...
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### What is the correct way to calculate the efficiency of a heat exchanger?

I want to evaluate the efficiency of a heat exchanger. From measurements I know all four temperatures $T_1$, $T_2$, $t_1$ and $t_2$ as well as the mass flows of both fluids $m_1$ and $m_2$ and if ...
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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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### Calculating cooling required in electrical panel box

I have a single electrical distribution panel in an insulated metal panel building (a standalone shed) which has no active cooling or air vents. I need to determine whether the latter are required in ...
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### Quick high-level sizing change estimate of heat exchanger loops when adding a second loop to a simple system

Say that I have a tank full of a hot liquid metal at ~700K. I want to passively remove heat using a Na loop with a Na-air heat exchanger. So I put in the loop, and I know it removes 100 kW. The Na ...
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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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### Nusselt number equations for external flow over a single finned tube heat exchanger

I am designing a heat exchanger that will utilize a singular finned tube of around 2" diameter with 4 fins per inch that are 3/4" tall and .03" thick. I am looking at finding the ...
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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/...