Heat transfer Definition and 947 Threads

Homework Statement Heat transfer problem with 3 insulated sides and heat flux in and out on one boundary. given values: q & k Homework Equations Governing Equation: \frac{\partial^{2}{T}}{\partial{x}^{2}} + \frac{\partial^{2}{T}}{\partial{y}^{2}} = 0 Boundary Conditions: @ x =...

Please can someone show me how to work out the following questions. 1) A hot water cylinder holds 500 litres. If the primary heat source is 30kW and the supply water inlet to the cylinder is 12°C, how long will it take to heat the whole tank to 60°C? 2) The primary side of a plate heat...

Homework Statement In Betty Crocker's cookbook, it is states that it takes 2h 45 min to roast a 3.2kg rib initially at 4.5 Celsius "rare" in an oven maintained at 163 Celsius. It is recommended that a meat thermometer be used to monitor the booking, and the rib is considered rare done with...

Homework Statement One day Susan collected the mercury from the thermometers around her house and found she had 3.50 cubic centimeters of mercury (density= 13.6 g/cm^3) at room temperature of 28C. She places the mercury in a small bag and drops it into liquid nitrogen (-196C).a. Calculate how...

Homework Statement Heat is transferred into saturated liquid water until it is saturated vapor. The water remains at 300 C throughout the process. a. What is the initial pressure? b. What is the final pressure? c. How much heat is transferred per kg of water? I'm having trouble...

Homework Statement Estimate how long it should take to bring a cup of water to boiling temperature in a typical 600 watt microwave oven, assuming all energy ends up in the water(assume any reasonable initial temperature for the water.) What can you conclude about the amount of heat added...

I want to calculate the temperature on the outside of a pipe which has a heated fluid flowing through it. If I know the temperature of the fluid and the ambient temperature, as well as all the material properties such as thermal conductivity and convective heat transfer coefficient, is there a...

What is "heat transfer coefficient" What is heat transfer coefficient? and where can i find a table listing it?

There are two insulated compartments separated by a thin wall. The left side contains .060 mol of He at a initial temperature of 600 k and the right side contains .030 mol He at the initial temperature of 300 K. The compartment on the right is attached to a vertical cylinder, above which the...

What force is responsible for the phenomenon of heat transfer?

compressed gas...and heat transfer... If you were to take a cylinder of air, at room temp, and let's say it is 100ml in volume. If you were to take this cylinder of air, compress its volume to half its size, how much heat would that create (btu's) and if the heat were to dissipate, would the...

How many days does it take for a perfect black-body cube (0.0100 m on a side, 30 degrees C) to radiate the same amount of energy that a one-hundred-watt light bulb uses in one hour? If someone could point me in the right direction with how to go about solving this problem i would greatly...

[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 fin is 80% efficient. Which design change would improve the heat transfer the most, assuming all other variables were held constant? (a) double the number of fins (b) double the length of the fins (c) find a new material with twice the conductivity (d) double the heat...

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...

I need help understanding what a math problem is asking for. Its a Fourier heat transfer problem but it just isn't making any sense to me and I don't know what the author is asking for. Homework Statement The heat flux through the faces at the ends of a bar is found to be proportional to un...

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...

I am working on my first heat transfer design and I have almost all of my data, but I do not know what to do with it. I know the following for the material on each side of a wall: specific heat viscosity thermal conductivity density velocity for the wall in between them I know the...

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?

We are experince imbalance heat in the hydrocraker combined feed exchangers which result in low tempreature in one side of the exchanger and high in the other side. The problem is unique and what ever the unit is depressurized the problem swith from one pass to the other pass. I would like to...

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...