Heat transfer Definition and 875 Threads

[b]1. Homework Statement [/b the ends of a 20cm long,2cm diameter rod are maintained at 0degrees and 100degrees by immersion in an ice-water bath and boiling water. heat is conducted through the rod at 4.5x10^4J/h. of what material is the rod made? Homework Equations Q/dt=k(A/L)dT The...

Can anybody explain why my numbers are not equally out? At work, I am trying to determine the heat transfer taking place in a water cabinet. Both loops have water in them. There is a counter current flow heat exchanger where the transfer takes place. I take the temperature measurements...

ok...Two identical rectangular rods of metal are welded end to end (hot dog to hot dog) with a temperature of 0 Celcius on the left side and a temperature of 100 celcius on the right side. in 2 min 10 joules is conducted at a constant rate from the right side to the left side. How much time...

hello i need to understand "view factor" in heat transfer(radiation), can anyone give me some documents that has some description about "view factor"? thnaks

Homework Statement Hello, first question here, A copper rod and an aluminium rod are in thermal equilibrium with each other. Copper rod = 50cm long and the aluminium rod is 20cm. Radius of pair is 8cm. Copper end is heated (and maintained) at 80C , other end of pairing is 20C. k of...

Homework Statement Hi, I'm tutoring an introductory Physics class at a Big 10 school, and we've stumbled across a problem that we can't solve. Well, I thought we could solve it, but we have to use a clumsy web program to enter our answers and we can't seem to solve this one. The problem is ...

Hi guys, I have a question in using comsol software, particularly on heat transfer. Its a 2D geometry. A rectangle whereby heat is applied on the top surface at the particular point and the 3 sides are thermally insulated. As more heat is applied over time, a hole will be created. A...

I'm looking for some number to use for a heat transfer coefficient of bare wire in still air. but not having much luck. This number just needs to get me into the ball park - I know it would be rather complex to solve with precision. Think of it this way - I have a length of wire dissipating x...

Hi, What are good first texts in mass and heat transfer, material and energy balances, fluid mechanics and thermodynamics? I was recommended Felder and Rosseau, and Incropera and Dewitt. However, no books have been recommended for fluids and thermo and the consensus on amazon seems to...

Hi everyone, I just want to know what is the difference if we analyze a heat transfer using finite element analysis software such as ANSYS, ALGOR, NASTRAN, etc., and using computational fluid dynamics software such as FLUENT, etc.? That’s all Thanks in advance Huygen

Homework Statement Diagram is attached showing part (a) and part (b) Two identical rectangular rods of metal are welded end to end (a), with temperature of T1=0 0C on the left side and a temperature of T2=100 0C on the right hand side. In 2.0 minutes, 10J is conducted at a constant rate...

I'm seek simple equation that estimate the heat transfer (W/K.m2), conductivity and thermal diffusion rate between cylinder metal rod, about 2 meter length with build in heater of say 10KW and the soil of different type of conductivity and thermal diffusion stated in most textbook. For...

Homework Statement A tank A is connected to a cylinder/piston as shown. The tank has a volume of 100 L and contains saturated vapor R-134a at 30˚C. When the valve is cracked open, the vapor slowly flows into the cylinder B. The piston requires a pressure of 200 kPa in the cylinder to raise...

Hi everyone Can anybody give me the meaning of 1)Total surface heat flux 2)Surface heat transfer coeficient 3)wall function heat transfer coeficient and difference between surface heat transfer coeficient and wall function heat transfer coeficient Please......

Say we have a box made of two materials (a box with an internal lining) and a lid for the box made of a certain material. If I fill the box with a heated liquid and cover a certain percentage with the lid, is the following calculation correct for heat loss in the liquid if you ignore any film...

I´ve found a webpage where the following problem is solved in detail, together with the substitution of numerical values into the pertinent formulas: A plate is of cross-section thickness L = 0.1 m and has an initial temp of To = 250°C. It is suddenly immersed into an oil bath of...

Homework Statement A steel bar 10cm long is welded end to end to a copper bar 20cm long. Both bars are insulated perfectly on their sides. Each bar has a square cross section, 2cm on a side. The free end of the steel bar is maintained at 100 celsius and the free end of the copper bar is...

i have set up an equation to get the heat transfer rate Q for a combined system where heat is transferred from a cylindrical outer wall set at 500 C. the wall heats a gas, which in turn heats a solid block of cylindrical metal positioned in the centre of the heated walls with a starting...

Hi, I'm trying to find some data on the entrance region of a curved duct with a rectangular cross section. Its a heat transfer problem where the fluid flows through a rotated duct. The distance of the duct is smaller than the entrance region for a straight rectangular duct of same...

Now I need to solve a transient problem involving both conduction and convection. Homework Statement In this problem there's a thin plate being heated by two constant-temperature sources. One small source is in contact with part of the plate. Another one is separated with the plate by air...

Homework Statement A copper calorimeter with mass 0.1 kg contains 0.15 kg of water and 0.012 kg of ice in their equilibrium at normal atmospheric pressure(0 degrees Celsius). If 0.5 kg of lead at 200 Celsius is dropped in calorimetr, what is the final temperature?( consider the close system...

Homework Statement A system consists of N pairs of non-interacting, spin 1/2 particles with magnetic moment \mu. It is initially immersed in a uniform magnetic field H_{i} while it is in thermal equilibrium with a reservoir at temperature T_{i}. While remaining in thermal equilibrium with the...

I am a little confuse here. I am trying to solve the 1-D Transient Heat Transfer for a Constant Temp. Surfaces "wall". The PDE is \frac{\partial T}{\partial t}=\alpha \frac{\partial ^2 T}{\partial x^2} T(to)=200*x I am not so sure about how I'm suppose to get the Temperature profile any...

This is the scenario.. I have a engine and the block is made of cast iron which is 1/2" thick. The internal temperature of the engine within the cooling passages is 260° F Is there a way to calculate an approximate surface temperature on the outside of the engine block? If so, what...

How do I work out the rate of heat transfer between different states of matter? Say for example I wanted to calculate how long it takes for a freezer at -15 degrees to freeze 30g of water in a cup at 10 degrees, what equations would I need to use? I've already worked out that 11,274 joules...

Can anyone help me solve this problem please ? http://www.hostdump.com/host/out.php/i18940_1.jpg

Homework Statement A gas mass 0.115kg undergoes an increase in volume from 0.25m cubed to 0.56m cubed. initial temp 32 degrees c and initial pressure 1.2bar. work out heat transfer?? Homework Equations W=P1V1 ln(V2/V1) W=mRT ln(V2/V1) P1V1/T1=P2V2/T2 Q=U2-U1+W PV=mRT The Attempt...

Hi everybody, I'm a new user of Comsol Multiphysics and Comsol script. And I'm working on a conduction problem, with convective and radiative heat flux at one boundary. The geometry is quite simple: 2D rectangle. But the upper boundary is supposed to be moving with time (linear or exponential...

hi, i was hoping someone could help me with a problem i am having. i have a 2D turbine blade, with many holes of different diameters through it that represent the cooling passages. i am trying to find an analytical solution of the temperature distribution so i can compare it with...

Suppose that I have an aluminum cube with side lengths 10 cm. Suppose that I uniformly and continuously apply a temperature of 60 degrees celcius to one of its sides. The medium surroudning it is air with a temperature of 27 degrees celcius. After t seconds, what is the temperature of the...

This is a forced convection heat transfer problem and would appreciate any help! Stack of steel billets is placed in a cooling chamber. All billets of the same row are touching each other and each row is spaced of 5 in. I want to calculate the convection coefficient and pressure drop across...

Homework Statement The solar constant is the amount of energy from the Sun we receive on the Earth during each second on a 1.000 m2 area oriented perpendicular to the direction of the sunlight. The value of the solar constant is about 1.37 kW/m2. Imagine sunlight illuminating an asphalt...

Does anybody know why thorium is better than uranium as far as heat transfer is concerned?

Heres's my question: is the "diffusion" part of convection (which I understand to be advection + diffusion) equivalent to simple conduction? This is of course assuming an incompressible fluid such that no natural convection is possible. I hope this is clear and to the point enough, but...

You are given a solid, homogenous block of material, 48x24x12 inches suspended in air at 70 degrees. The block is initially at 70 degrees as well. Then, a laser is used to heat one corner of the block to a constant 200 degrees. Model the heat transfer through the block and report the average...

If I stand at the corner of a largely room with a room-temperature and burn something with flames for few seconds, it'll hardly change the temperature of the other corner far away. Yet, If I whistled event softly it could be clearly heard at any point in the room -instantly-. Each phenomena...

Homework Statement a thick walled tube of stainless steel, ks=19W/m.K, with a 2cm internal diameter and a 4cm outer diameter is covered with a 3cm thick layer of insulation. If the inside and outside wall temperatures are 600C and 100C respectively and the thermal conductivity of the...

If I had a piece of steel 0.25" thick 1 meter wide and 1 meter long and it was at 100 deg C and it was immersed in a bath of zinc at 460 deg C how long would it take to heat the piece of steel to 460 deg C? Would this be down the lines of Fourier's Law of conduction? q=...

Hi all. Why Reynolds Analogy and other empirical relations always overesimate heat transfer? I have done an experiment on turbulent pipe flow (smooth pipe) and I used Reynold Analogy (both the simple (Pr=1) and the modified one) and the Dittus-Boetler correlation equation to do the...

I got into a discussion about heat sink materials and was beaten up for suggesting that Aluminum is better than Copper because it will transfer the heat away from itself much faster than copper. Copper has about half the specific heat and about twice the thermal conductivity over Aluminum. Am...

Hi, I have to determined the rate of heat transfer in a delivery dock when the big garage doors are open. I have tried a natural convection approach, but I lack the mass air flow from the inside of the garage (22°C) to the outside (-10°C). Or is there another way to calculate this? Thanks...

Heat transfer and Fluid Mechanics, COMSOL Help Hello, I am trying to couple heat transfer and fluid mechanic together, model is a simple concrete slab (3'x6')with a water pipe beneath it and along 3' direction. For heat transfer, the heat flux will apply on the surface of concrete slab...

Heat does not naturally flow from a cool body to a hot body. A refrigerator, however, does remove heat from the icebox and expels it as warm air to the outside world. What is required to make this process function?

Homework Statement a rectangular plate (15 x 30) with the following boundary conditions: u_y(x,0) = 0 u_y(x,30) = 0 u_x(0,y) = 0 u_x(15,y) = y(20-y) the derivative B.Cs describe the heat flux through the boundaries. solve the the steady-state temp u(x,t) Homework Equations...

Homework Statement A 300 cm3 glass is filled with 120 g of ice at 0°C and 210 g of water at 25°C. (a) Characterize the content of the glass after equilibrium has been reached. Neglect heat transfer to and from the environment. Find: mass of water? mass of ice...

Not sure where to put this post, care more about what's happening on atomic scaI le so i put it here. I am currently taking Heat transfer for engineers and we were discussing the mechanicals for heat transfer, conduction, convection, raditation. In class my professor said that conduction is...

I am currently enrolled in a course on Spacecraft Thermal Control, and, in addition to the Satellite Thermal Control Handbook, we are to purchase a book on heat transfer to use as a reference for the course. Does anyone have any recommendations? Listed below are some of the ones the professor...

A piece of metal with a mass of 1.50 kilograms, specific heat of 200 J/kg · C°, and initial temperature of 100° C is dropped into an insulated jar that contains liquid with a mass of 3.00 kilograms, specific heat of l,000 J/kg · C°, and initial temperature of 0° C. The piece of metal is removed...

How does heat tranfer in motional bodies? Homework Equations The Attempt at a Solution

If I have a fluid, initial temperature and flow rate known (and constant), that is flowing through a heating element (heat given in Watts), what equation do I use to determine how long it takes the fluid to reach a certain temperature? This is a transient problem, for a closed loop system.