Heat transfer Definition and 947 Threads

Homework Statement How much energy is required to change a 46.0 g ice cube from ice at -10.0°C to steam at 116°C? Homework Equations specific heat c = Q/(m(Tf-Ti)) Q = cm(Tf-Ti) latent heat Q = mL The Attempt at a Solution 2.05*10*46+4.1813*100*46+2.080*16*46 +...

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Lets say a hot object is at 500K and placed in a chamber with wall temperature of 300K. The surrounding air in the chamber is 320K. So what is the mode of heat transfer for the hot objection? There is convection and radiation. so the heat transfer rate, q = q(conv) + q(rad), right...

Homework Statement A rod with length L and section A has its extremities in contact with 2 springs of heat whose temperatures are T_A and T_B such that T_A>T_B. The rod is an environment where the temperature is worth T_0 (constantly). a)Determine the function T(x) that describes the...

What is the efficiency of induction heating? What if you only had 8800 Watts available, or perhaps 220V, 40Amp... what size iron object could you heat, and to what temperature? Size will have to be qualified... how long? What shape & how thick? Depth of heat penetration. Then how long would it...

Hi, I am studying the heat transfer in a stirling engine. The basic situation is a pipe blocked off at both ends, with air inside, and a displacer also inside, that moves backwards and forwards inside. It is not tight against the walls of the pipe, and air can pass around it. One end of...

Homework Statement A 4-in.-OD pipe is used to transport liquid metals and will have an outside surface temperature of 1400 F under operating conditions. Insulation 6-in. thick and having a thermal conductivity expressed as k = 0.08(1-0.0003T) where k is in [Btu/hr*ft*F] and T is in [F], is...

A student produces heat with a rate of 100W. How much heat is transferred from 90 students to a classroom in 50 minutes? Attempt at solution: 100W (100 J/s) * 90 students * 3000 seconds = 2,7 * 10^7 J. Does this make sense? The classroom is 3200 cubic meters and the air in it has a...

Ok please can someone help or at least point me in the right direction with this question please? I have air flowing through a pipe which is heated to 477 degrees via burners on the outside. The pipe itself is heated to 550 degrees and there is a thermocouple inside the air flow. However, the...

Ok it's my first time here and I was hoping to get some help on some questions I have been given. I am a first year chem eng and I'm finding the work pretty hard so any help at all will be useful, thanks. I need to find the convective heat transfer coefficient, h for petrol using this...

Homework Statement For the equation mc\DeltaT, i suppose \DeltaT should be Tf - Ti. However, at what condition we should let \DeltaT be Ti - Tf? I did come across a question which requires \DeltaT be Ti - Tf for a heat lost by an object. eg, heat lost by copper = heat absorbed by...

Homework Statement A tent being considered for cold-weather conditions has insulation on the top and sides with a conductivity, k = 0.040 W/(m*K) and a thickness, l = 0.50 cm. The tent (and surrounding medium) has the following conditions: a heater (inside the tent) producing heat at a rate...

Homework Statement Saturated liquid H2O @ 500 kPa flows in a metal pipe, 5 cm inner diameter and k=40 W/m K, with wall thickness 3 mm @ a rate of 2 kg/s. The pipe is exposed to ambient gas @ 500 degrees C with h=100 W / squared K. The water is being boiled to come out as saturated vapor @...

Homework Statement http://img94.imageshack.us/img94/7101/45580214.jpg The Attempt at a Solution I'm trying to see if anyone will give me pointers on how to complete this assignment; because the professor is not helpful...at all.

Hi everyone. I am starting using Comsol modeling the temperature field of a buried cable installed into a PVC duct (2D problem). I have already solved the problem considering heat transfer by conduction. To do this, I have used the Electro-Thermal Interaction Application Mode (Perpendicular...

Hello, I hope this is the right place. Which of the following is false? a. Convection only takes place in gases and fluids. b. Heat radiation can take place across a vacuum. c. A perfect radiating surface has an emissivity (e) = 1. d. A perfect heat insulator has an...

Hey everyone, I'm new to the forums here and just have a question. Homework Statement A piston-cylinder device contains a mixture of .2kg of H2 and 1.6kg of N2 at 100kPa and 300K. Heat is now transferred to the mixture at constant pressure until the volume is doubled. Assuming constant...

Hi there, first of all: This is not a homework task or something like that. It is just one of my interests and I want you to check my calculation, if my thoughts are correct or not. Furthermore I apologize for my incorrect englisch but I am a foreigner. Okay, now some background...

What is the effect of different tube material (conductivity) on the heat transfer from water in an infinite tube to a surrounding infinite solid? The actual practical application is transfer of heat from hot water (~180F) in 3/4" tubes into sand for heat storage (and then the transfer back)...

l have a tube. and air enters the tube at a certain temparature and pressure. the air is threated as an ideal gas. Also, we know the exit pressure of the gas. In additon to those, we know radious of the tube.. How do we find the heat transfer rate.?

Homework Statement I have a cylinder that's made up of three sections, brass, stainless steel, brass. There's a heat source at the top and a heat sink at the bottom. I know the overall heat transfer coefficient, power supplied to the heater, length, diameter, cross-sectional area of the...

Homework Statement How much Fe at 200.0C must be placed in 100.00g of water at 20C so that the temperature of both will be at 35.0? Homework Equations Q=MCdeltaT The Attempt at a Solution Energy required to raise water is 6300 J So I did by: (keep in mind I used sig figs)...

Sorry for the long post but I could use some help. I am having a problem with a professor in my heat transfer class and I was wondering if anyone could help. Before I go on, I am not looking to get points back on my test, I only lost 2 so I don't care, I just want to know whether I am right...

I am trying to solve an advanced heat transfer problem and I have a 2nd order ODE. I can solve the homogeneous solution easily, but I am having trouble with the non-homogeneous solution.Homework Statement Given a turbine blade and asked to model as a one-dimensional fin, subject to the...

Homework Statement We're currently studying steady state one dimensional conduction heat transfer. We've touched on some surface convection, resistances in layers and fins. I don't think I'll have much issue with this problem once I find this out: What is a thermal driving force?

Greetings, I'm trying to design a system that creates a thermal gradient in 2 dimensions through several layers of very different material (copper, acrylic, and ice). I was wondering if there's some cheap software available or even some kind of shareware out there that could give me at least...

Homework Statement A nail driven into a board increases in temperature. Homework Equations If we assume that 60 % of the kinetic energy delivered by a 1.80-\rm kg hammer with a speed of 7.80 \rm m/s is transformed into heat that flows into the nail and does not flow out, what is the...

I'm super confused about this problem. I don't even know where to start. It seems very simple, but I just can't figure it out.. An electrical resistor is connected to a battery. After a brief transient, the resistor assumes a nearly uniform, steady-state temperature of 95 degrees C, while the...

hi this is my first post on this forums hope every would help me here on this question Homework Statement outside vertical tube = 1m outside diameter = 80mm exposed to saturated steam at atmosspharic preasure & is maintaiined at 50 c by the flow of cool water through the tube. Rate...

Please help me with this : 1) Water circulates throughout a house in a hotwater heating system. The water is pumped at a speed of .7 m/s through a 4 cm diameter pipe in the basement under a pressure of 3 atm. What is the pressure, to the nearest N/m^2, in a 2 cm pipe on the second floor 5...

Homework Statement Two rooms, each a cube 4.0m on a side, sare a 12cm thick brick wall. Because of a number of 100-W light-bulbs in one room the air is at 30 Celsius, while in the other room it is at 10 Celsius. How many of the 100-W light-bulbs are needed to maintain the temperature...

Hi I am wondering if anyone can point me in the right direction. I am trying to solve a heat transfer problem. There was a fire in a propylene plant and the metal piping was damage in the fire. I know that the total heat of the fire is about 2371 btu/ft^3. And the total amount of fuel in...

Homework Statement I am trying to get the units to match up on both sides. \frac{\partial T}{\partial t} = \frac{\nabla ^{2} T}{k} = \frac{1}{K}(\frac{\partial ^2 T}{\partial x^2} + \frac{\partial ^2 T}{\partial y^2} + \frac{\partial ^2 T}{\partial z^2}}), where k is the thermal resistivity...

I have a simplified model (see attached picture) which is part of a bigger model but for now the problem is as follows. I have a electropolished metal sheet which has spots on it which act as heat sinks because they are kept at constant temperature of 100K. The sheet is at room temperature...

I am trying to calculate the length of a pipe needed for an air cooling system I have found the following formulas: R=1/(h*a) where h is the convection coefficient and a is the surface area. h=Nu*(k/L) where Nu is the nusult number and k is the thermal conductivity. a=π*d*L where d is the...

This should be a fairly easy problem, although my Heat Transfer is quite rusty. I'm trying to get a ballpark estimate for a rotating cylinder that has flow on both the inside and outside. I know the temperature of the air at the inlet and outlet and am trying to get a decent estimation for...

I have a problem where the coefficient of thermal conductivity changes as temperature changes. Where/how do I input this into comsol?

Homework Statement (a) A 0.5kg mass of copper (specific heat 385 J kg-1K-1) at 600K is plunged into a litre of water at 20C. What is the equilibrium temperature, T2, of the system? What is the change in entropy of the water? (b) A litre of water is heated slowly at a constant rate from 20C...

Hi Everyone, I'm using Comsol v.3.4 to model a 1-meter copper rod experiencing a Temperature change of 294 Kelvin (4K at bottom and 300K at top). I have a slow computer/connection to the server, so I can't see any 3-D images or the Temperature plots. I'm working in the axial symmetry (2-D)...

Hi everyone... I am doing a problem on heat transfer on multilayers... want to find out the emmisivity of some materials like silicon, silicon dioxide, Nickel, Tungten... Can anyone suggest me some papers or links or good books to get the emmisivty of these materials... Thanks in advance

0„2When one steps from a shower on a cold morning, why doesthe tile floor seem so much colder than the air?

y Could some one please help me. My professor for a lower level programming class (in labview) has given the class the following assignment. This is not a heat transfer class and he has not spoken/taugh us anything related to heat transfer. He emailed us a few pages from a heat transfer...

Homework Statement I have uploaded the problem statement and corresponding programs. Reader is the problem statement Reader1 is another file that is suppose to help Homework Equations I'm just having trouble getting started. I can do the analytical part on paper, but I don't know...

Homework Statement A piece of metal with a mass of 1.50 kg, specific heat of 200 J/kg*oC, and initial temperature of 100oC is dropped into an insulated jar that contains liquid with a mass of 3.00 kg, specific heat of 1,000 J/kg*oC, and initial temperature of 0oC. The piece of metal is...

Homework Statement A plane wall of 152 mm thickness has surface area of 2.32 m2. One side of the wall is kept at 82.2 oC, and the other side at 4.4 oC. The thermal conductivity of the wall material is 0.036 W/m.K at 0 oC, and that at 93.3 oC is 0.055 W/m.K. Calculate the rate of heat...

Heat transfer problem--please help Homework Statement I have a heating mantle (180Watt) and i want to use it for heating a ceramics flask (thermal conductivity : 1.38 W/m*K), however, there is a stainless steel on top of the flask (at 10cm distance between the heating mantle and the...

Homework Statement I am working on a Matlab code that will solve a temperature grid for a 2D transient heat transfer problem. The code seemed to be working well but when I changed the timestep (to find timestep independance) I noticed that the larger the timestep, over the same duration, the...

what is the measurement for describing heat transfer rate if i know the specific heat of the objects? as example, i want to know if the heat transfer rate of a hot copper block attached to a block of room temp aluminum is different than same hot copper attached to a block of gold at room temp...

Homework Statement The pressure on 0.01 litres of mercury is increased reversibly and isothermally from zero to 1000 atm at room temperature (293 K). Mercury has a coefficient of volume expansion β = 1.82 × 10−4 K−1 , and an isothermal compressibility κT = 4.02 × 10−11 Pa−1 . Note: 1...

Homework Statement If 4.0 g of boiling water at 100.0°C was splashed onto a burn victim’s skin, and if it cooled to 45.0°C on the 37.0°C skin, (a) how much heat is given up by the water? (b) How much tissue mass, originally at 37.0°C, was involved in cooling the water? Homework Equations...