Heat transfer Definition and 947 Threads

In answering questions (a.) Why heat intake in this system is ## \Delta Q_{sys} = ( \Delta Q_{hot water} + \Delta Q_{cold water} ) / 2 ## where. ##\Delta Q_{hot water} = c(T_1 - T_f) ## ##\Delta Q_{cold water} = c(T_2 - T_f) ## I think T or T_f should be between T_1 and T_2 But why is the...

Hi, I'm looking to find a very very basic model to calculate the heat transfer coefficient in a tube with given heat power exchanged ##Q##. The fluid inside the tube starts sub-cooled (##T_{in}## is known) but exits the tube with a quality of steam around 0.15 (pressure is supposed constant)...

Summary:: Determine the temperature distribution in a bar (very long– 2D) with rectangular cross section, in steady state, with imposed flux at one face, convection at the opposing face (Tinf, h), and imposed temperature (T1) at the two remaining walls. I am trying to find the analytical...

Are there any known instances of heat transfer via conduction or convection happening at relativistic speeds? Is this even possible or is there a non-relativistic limit to how fast heat can transfer in these ways, like how sound can only move so fast?

Hello! I'm currently studying meridional heat transfer, but I'm struggeling to understand the attached figure. I don't understand why the ocean contributes more than the atmosphere near the equator and why it suddenly falls off towards the mid-latitudes. Also, why the atmosphere peaks at...

I have completed Q1 and Q2 (i - iii); not sure if I correct in my answers; i would be very grateful for any feed back, thanks.

Hi, I was recently attempting the following problem from heat transfer and I didn't really know how to include the fin amongst the other thermal resistances in the problem. The key quantities are: ## T_{in} = 20 C ##, ## T_{out} = -5 C ##, ## h_{inner} = 5 W m^{-2} K^{-1} ##, ## h_{outer} =...

as T_∞ = 0 , I use Q=−F\epsilon A\sigma T^4 for this problem as the integration is much easier, so we start with mcdTdt=−F\epsilon A\sigma T^4 rearrange so T is on one side and t is on the other: −mcF\epsilon A\sigma T^4dT=dt on the left side I integrate from the initial temperature (Ti)...

When we measure 'the rate of conduction heat transfer'=Q , we assume that the hot side and the cold side's area are same. But if the both side's area is different to each other, how can i know the rate of conduction heat transfer? like below figure. Would you like to help me?? Thanks.

I would like to fully understand two parameters involved in convection heat transfer systems. I have read the document https://fenicsproject.org/pub/tutorial/sphinx1/._ftut1005.html, and I am interested in the parameters ##r## and ##s## in eq. 69. As far as I understand, when one solves the...

I have come across this problem from this booklet: https://www.ioc.ee/~kalda/ipho/Thermodyn.pdf

Hi, the approximate (not accounting for plate size and separation distance) formula for heat flux exchanged via radiation between two parallel plates is: $$q=\frac{\sigma (T_{1}^{4}-T_{2}^{4})}{\frac{1}{\varepsilon_{1}}+\frac{1}{\varepsilon_{2}}-1}$$ where: ##\sigma## - Stefan-Boltzmann...

Hi guys, I am confused about the heat transfer mode of between two contacting material, especially in a channel flow. Obviously, conduction or convection dominate the heat transfer process in the process with low object temperature . But I am not sure if I have a fluid of 500 Kelvin, flowing...

Good evening everybody. I am new here I hope it is okay to ask this question here. As part of a project I am trying to examine the effect of a pulsating laminar duct flow on the heat transfer behavior for constant heat flux at the wall for a Newtonian incompressible fluid. As such I am...

How to modify this Formula? and arrive at the solution. Q = -K(Th-Tc)A/thickness

The intensity is proportional to the square of the distance between the source and the body and also depends on the angle of incident. I = The intensity at 0° (Assuming I = some constant) then I0 = I cos(Theta) Theta = the angle of incidence. I want to solve this using trignomentry. Is it...

I have two bodies, one at a higher temperature say 1000°C (Body A) and the other is at 22°C (Body B). Body A emits Radiation (Surface to Surface interaction). The temperature of Body A is maintained by a constant supply of Energy. The Body B will absorb the Radiation Energy from Body A, and its...

Here is one scenario: I have placed a metal in my room which is at room temperature. Air has little much heat capacity and metals don't like to store heat. Would heat transfer occur? Whatif I set the temperature of both to a certain degree where it crosses heat capacity of metal but not of air?

Hello- In the attached screenshot from my textbook, I am trying to understand how they get from equation 6.5 to 6.5a. I have attached my attempt to solve it, but I am stuck evaluating the left side. I do not see how to get their result. Relevant information: k, T_w, T_inf, h and L are all...

Hi, when modeling convective cooling in FEA one needs to define film coefficient ##h## and ambient temperature ##T_{amb}##. The software calculates convective heat flux using this data and current surface temperature ##T_s##: $$q=h(T_{s}-T_{amb})$$ However, modeling of moving cooling nozzle may...

Hi, So there is already a written solution which I have, but this is more a question about why we omit reflection that come back to the same mirror? Method: Let us consider one of the mirrors, we know it will emit a heat flux given by: q_{1} = \epsilon_{1} \sigma T_{1}^4 . Given that we are...

Assume there is a boundary separates two medium with different heat conductivity [κ][/1] and [κ][/2]. In one medium, the temperature distribution is [T][/1](r,θ,φ) and on the other medium is [T][/2](r,θ,φ). What is the relationship between [T][/1] and [T][/2] ? Is it - [κ][/1]grad [T][/1]=-...

Hello, I'm looking for the governing equations for the laser radiation on a surface. I understand there are several types and methods. I was wondering if there is an equation to show all the parameters in calculating a surface temperature after laser radiation for a specific time. Some of the...

Hey guys. I have a room which i want to use as a server room. the devices need to work 24/7 and they get pretty hot. so it is imperative to keep the room cool otherwise the devices will be damaged. I have an air vent to bring cold air into the room for the devices so their fans can suck in cold...

Hello, I am a Mechanical Engineer a little out of practice on Heat transfer. I am trying to solve this problem. It must be solvable but i have yet to find right equations online. I have a multi Layer Cylinder made up of C350 marraging Steel,Zinc Alloy-12 , then 6061 Aluminum T6. All that is...

I am trying to determine the size of a single cartridge heater or 2 cartridge heaters to heat a large mass of aluminum to 400F. The aluminum block will be sitting inside an insulated (all sides) enclosure. The following are the specs for this problem. - Max surface temp of aluminum block is...

Can anyone please guide me in what I'm missing to answer part b)i? I can't seem to work out the thermal conductivity (k) in order to find the heat transfer by conduction? Or is the different approach that I must take to do this question? Thanks for any help!

I attached below my attempt to solve the question.

I) Area = 3.14 x L xD 3.14 x 60 x 0.11 = 20.72m2 Q=UADT = (1.0Wm2k-1)(20.72m2)(150-20) = 2693.6 W Changed flow rate from 0.1kgs-1 to 360kghr-1 II) Enthalpic Capacity in dry steam = steam flow rate x latent heat vaporisation Q=mDh = 360 x 2114 (formula looks for lat heat vap but we have latent...

Hello, I have a question with regard to equipment design. How do I calculate the overall heat transfer coefficient for a large pipe who has smaller pipes in it? Say I have water flowing on the large pipe, and inside it there are three pipes with hot acid in them. Assuming they flow concurrently...

I'm trying to find a heat transfer equation that includes time. Metal tank, partially filled with liquid. I need to find the time it would take for the temperature on the outside of the tank to drop from θ2 to θ1, given thickness, metal and liquid's properties, and tank dimensions

Hi! Came across this forum while researching my project, and this seems like a good place to ask. Thanks in advance! I'm building a hot tub that will use a 55 gallon steel drum wood stove as a heat source. The drum is built into one of the sides so that the majority of the stove is surrounded...

I tried modeling the problem quite a few ways. one was to say that the difference between the heat emitted by the room and the heat emitted by the bulbs would equal the heat absorbed by the room, and that could allow us to calculate temperature. This did not work. I'd appreciate your help

Is anyone able to explain something to do with entropic force at a level I might be able to understand please! Ok... you need to know what level I'm at? Formal Maths & Physics at high school (I'm 50, so distant past :-) Informal Maths & Physics - lifelong interest. Consume a lot of youtube...

Hello guys, :smile: So like the Titels says I am Trying to get an Approximation of the Heat Transfer which ocours in a Deware container. Unfortunately all my calculations so far seem to suggest way to low Boil off rates for my Container its just to efficient, here is a summary of my Attempts...

To write the equation I took as the control volume the following block: and the equation I wrote are: $$ 6m_{f} c_{p_{f}} \frac {dT_{f}}{dt} = 6P - \frac 1 {R_1} (T_f - T_g) \text{ for the fuel}$$ $$ m_{g} c_{p_g} \frac {dT_{g}}{dt} = \frac 1 {R_1} (T_f - T_g) - \frac 1 {R_2} (T_g - T_c)...

If one considers the kinetic theory of gases, can a first order estimate of thermal transfer be performed by considering momentum exchange at the container's surface? I understand the basics of explaining and calculating pressure with the kinetic theory of gases, but if we assume energy is...

I worked on a lab experiment that was meant to measure heat capacity but left me with some other questions. The students measured the mass of a cup of liquid nitrogen as it boiled off, recording mass vs time. Then they drop a solid object into the bath, one experiment with a small bit iron...

If I am honest with you I don't even know where to start, if someone wouldn't mind helping me find a starting point? Additional information Melting point of aluminium 660°C Specific heat capacity for aluminium (cp): 0.91 kJ/kgK...

Problem Statement: This is a question I made up to understand more about the calorimetric power. The equation below is given by Koda et. al (2003). A saucepan of water (400 mL) on a stove is been heated at constant temperature. The calorimetric power can be written:##Power(W)= (\frac{dT}{dt})...

There are similar problems with heat conduction only where for example, right side of the bar also has a certain temperature or in-contact with a hot material. However, in this case diffusion and convection occurs on the right side of the bar, more precisely on the Y material. I guess we have to...

I am working on a project to dry liquid digestates (residue from the fermentation process of biogas plants). The liquid digestate has a dry matter (DM) content of about 3%. The digestate is primarily made up of animal manure and maize silage. It is a non-Newtonian fluid having a viscosity of 4...

This question is in a unit about emission and absorption, Atomic Physics So far, I calculated the Power that the person gives off which is by using the S-B law formula. P= (s-b constant)*1.8*305K^4= 883 W (or Joules per second) for the ambient i used the same formula and found P= 702 W I...

Heat transfer: Conduction - Convection - Radiation, but I was wondering if conductive transfer is actually radiation transfer, but at contact distances; well not really contact since no material actually touches each other (at a quantum level). So, is conductive heat actually being...

I am currently trying to solve a problem for my dissertation. Help would be greatly appreciated. :) A silicon solar panel of area 1m^2 is being warmed by the sun. It achieves a constant temperature of 80 degrees celcius. I am trying to cool this panel which is constantly being provided solar...

Hi, I am a makeup formulator and need to make a lipstick that would be stable at 50ºC. The stability is tested in a chamber with an inner temperature of 50ºC. The lipstick is in a plastic packaging - a regular one that can be seen in any store. The question is: Will the temperature of the...

I have an interest in storing, for later use, energy from excess shaft power developed by a wind turbine. Currently I am assuming that the compressor is running in a steady fashion, continually drawing 300K, 1.0 atm. air into the compression chamber and compressing it to 20 atms. before...

Homework Statement Could someone look through my work? The parts where I wrote (??) are steps I am especially unsure about. Many thanks in advance. A large reservoir at temperature ##T_r## is placed in thermal contact with a small system at temperature ##T##. They end up at temperature...