Heat transfer at different temperatures
Heat transfer at different temperatures
(OP)
Hi All.
I have a simple question but I am not sure if the answer is that simple.
Is it possible to ensure that a component always incresases its temperature regardless the temperature of the cooling media?
The question comes from the test of an electronic component.
My specification requires that when the cooling media (air) is 60 degrees the component incresases its temperature 15 degress.
The manufacturer has tested the component with air at 20 degrees and the component has increased its temperature 15 degrees, therefore he ensures than at 60 degress of cooling media (air) the component will also increase 15 degress.
Is this correct?
I think it is a good question
I have a simple question but I am not sure if the answer is that simple.
Is it possible to ensure that a component always incresases its temperature regardless the temperature of the cooling media?
The question comes from the test of an electronic component.
My specification requires that when the cooling media (air) is 60 degrees the component incresases its temperature 15 degress.
The manufacturer has tested the component with air at 20 degrees and the component has increased its temperature 15 degrees, therefore he ensures than at 60 degress of cooling media (air) the component will also increase 15 degress.
Is this correct?
I think it is a good question





RE: Heat transfer at different temperatures
Tara
RE: Heat transfer at different temperatures
I will rewrite the requirement.
My specification requires that when the cooling media (air) is 60 degrees the component incresases its temperature ONLY 15 degress.
Thanks.
Jaime
RE: Heat transfer at different temperatures
As it stands the increase of the component temperature will be greater than 15 degrees if subjected to air above 20 degrees, also the temperature of your component needs to be considered, ie if your component is at different temperatures when the coolng air comes into contact, then its temperature increase will be altered.
Unless I have misunderstood your question.
desertfox
RE: Heat transfer at different temperatures
RE: Heat transfer at different temperatures
Tara
RE: Heat transfer at different temperatures
The electric motor has a cooling system based on cooled air.
When the cooled air is not provided, the electric motor has to be derated and the components should not be heated above 80 degrees.
During the FAT the manufacturer carried out the test without cooled air (at 20C)
With air at 20C the weakest component of the electric motor reached 37C, so it increased by 17C. The manufacturer then assures that if the air is at 60C then the component will only reach 77C.
Is this correct?
Thanks in advance.
RE: Heat transfer at different temperatures
RE: Heat transfer at different temperatures
Tara
RE: Heat transfer at different temperatures
RE: Heat transfer at different temperatures
Moreover "component incresases its temperature ONLY 15 degress"[sic] is not a reasonable requirement in English. It is almost but not quite the same as without the "ONLY," A better requirement is, "component incresases its temperature by no more than 15 degrees," or, "component incresases its temperature less than or equal to 15 degress," would be the normally accepted wording. A more comprehensive specification would include directly, or by inference, "over ambient temperatures of -XX°C to +80°C," or similar. With clear requirements, it is the required of the supplier to demonstrate by analysis or by testing that the requirement is met. Depending on the contract, the client may have had the right to review and alter the acceptance and FAT procedures to make relevant and meaningful tests of the article in question.
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RE: Heat transfer at different temperatures
RE: Heat transfer at different temperatures
R1 R2
Telement------------Telectronics---------------Tambient
Telectronics-Tamb)/R2=Q
R1, R2 the thermal resistances.
Q= power delivered to the component
Assuming the power remains constant, then the differential,( Telectronics-Tamb), varies directly as the thermal resistance or inversely as the conductance. And as noted above we expect R2 to decrease with rising temperature.
RE: Heat transfer at different temperatures
You did not say what kind of degrees you are talking about. They appear to be centigrade.
My crude rule of thumb would be that if ΔT were 15C° at 20°C, then it would be 15C° at 60°C. This all works as long as all your components do not behave differently at the higher temperatures. This seems to me to be a risky assumption.
In absolute terms, 20°C and 60° are very very approximately the same (293°K versus [333°K). Actually, I would expect ΔT to be a centigrade degree or two higher at the higher temperature.