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Thread: Heat Transfer Exam Question
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24-03-2007, 03:22 PM #1
Heat Transfer Exam Question
Exam question:
Heat transfer takes place whenever there is a:
a Pressure difference
b Temperature difference
c Specific heat difference
d Latent heat difference
Any thoughts on this question would be very welcome, thanks.
Thanks
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24-03-2007, 07:25 PM #2
Re: Heat Transfer Exam Question
The answer has to be 'B' surely.
It doesn't matter what the type of heat is it's the fact that there is a difference that makes the transfer occur.Brian - Newton Abbot, Devon, UK
Retired March 2015
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24-03-2007, 11:13 PM #3
Re: Heat Transfer Exam Question
Well our tutor would agree with you but thinking of the psychrometric chart - I would say 'C' is more correct - after all, temperature is not heat...
Anyone else got an opinion?
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24-03-2007, 11:18 PM #4
Re: Heat Transfer Exam Question
OK, I'll pose this question...
How do you quantify the difference between two items of different latent heat?
(Latent Heat is defined as the heat which flows to or from a material without a change to temperature. The heat will only change the structure or phase of the material. e.g. melting or boiling of pure materials)
(The amount of heat transferred delta Q is proportional to the temperature difference delta T between the objects and the heat capacity c of the object.)Last edited by Brian_UK; 24-03-2007 at 11:23 PM.
Brian - Newton Abbot, Devon, UK
Retired March 2015
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24-03-2007, 11:50 PM #5
Re: Heat Transfer Exam Question
The answer is "B" as you need a Delta T for either specific heat or latent heat to be absorbed or given up.
So I agree with Brian on this one, without this principle which is the second Law of Thermodynamics we all would be out of a job.
Ian
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25-03-2007, 02:21 PM #6
Re: Heat Transfer Exam Question
Have given this some more thought now - obviously not C as specific heat is amount of energy per unit mass to raise by one degree (or temperature unit) so C just does not make sense - I agree B is correct. Thanks for the help, I was stuck on the definition of temperature - for example the same level of heat can be given by different temperature scales, therefore a difference in temperature does not necessarily cause flow of energy... what a muddle... thanks... !!!11
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25-03-2007, 04:46 PM #7
Re: Heat Transfer Exam Question
The temperature scale (Fahrenheit, Celcius, Rankine, Kelvin) is a MEASURE of temperature (heat energy) from a base point, whereas Specific heat or Latent heat are a measure of heat carrying capacity.
Pressure has nothing to do with temperature in this instance.
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26-03-2007, 12:01 AM #8
Re: Heat Transfer Exam Question
Frank
specific heat is a measure of heat carrying capacity whereas latent heat is the amount of heat required to change phase so not really heat carrying potential, or am I being a tad pedantic.
Ian
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26-03-2007, 09:11 PM #9
Re: Heat Transfer Exam Question
Hi Ian
Nit Picking, hmm, maybe. Seems we've covered it now though
You know what I was trying to say
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13-12-2008, 11:51 AM #10
Re: Heat Transfer Exam Question
Heat tranfer depends only where, there is difference in temprature.......
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13-12-2008, 04:19 PM #11
Re: Heat Transfer Exam Question
There is no transfer if there is no temperature difference.
The answer is B.