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-   -   How to measure total Heat Power (http://www.cfd-online.com/Forums/ansys/80725-how-measure-total-heat-power.html)

myyahaha October 5, 2010 01:41

How to measure total Heat Power
 
1 Attachment(s)
Hi every body .
I'm learning to use Ansys ICepak to solve Heat problem . How ever I don't know to measure or get information about the most important thing in Ansys Icepak_ Heat power.
I'm searching some datasheets about : transistor, capacity and fan. However i don't know how to see the heat power because i'm ameatur . CAn you help me?
Thanks you very much.


Here is an example of a transistor's datasheet that i attached.

myyahaha October 6, 2010 10:13

Can anyone help me please?

bighead October 26, 2010 10:30

Usually, objects such as transistors are not modeled in ICEPAK. What you could do is to either modeled it as a planar (2d) or volumetric (3d) heat source. For most packages, such as BGA where the heating is usually a very thin layer, a 2D source is a gd simplification. For others where the temperature gradient in the block is important, den assigning a power to a block with thermal conductivity is good enough. However, if that is not important but you wanna retain the geometric characteristics of the block (for flow analysis), then you can use a 3D source.

After solving, you may wanna check how much of the heat flow goes to each of the 6 sides. So you can go to report summary and choose the object and indicate its high/low side. If all 6 sides are needed, than you can unchecked the combined values.

For fans/opening, you can do the same as well.

maybe you can describe in more details what you wanna model, and I can help you further.

myyahaha October 27, 2010 12:31

Quote:

Originally Posted by bighead (Post 280813)
Usually, objects such as transistors are not modeled in ICEPAK. What you could do is to either modeled it as a planar (2d) or volumetric (3d) heat source. For most packages, such as BGA where the heating is usually a very thin layer, a 2D source is a gd simplification. For others where the temperature gradient in the block is important, den assigning a power to a block with thermal conductivity is good enough. However, if that is not important but you wanna retain the geometric characteristics of the block (for flow analysis), then you can use a 3D source.

After solving, you may wanna check how much of the heat flow goes to each of the 6 sides. So you can go to report summary and choose the object and indicate its high/low side. If all 6 sides are needed, than you can unchecked the combined values.

For fans/opening, you can do the same as well.

maybe you can describe in more details what you wanna model, and I can help you further.


Hi Bighead. I appriciate that you answer my question. However I think you maybe misunderstand. I already know how to model an Ansys Model but my question is "how to get information about the heat source?" . How to measure total heat power of an object by someway such as datasheets.. to fill information in Ansys model.
Can you help me please?
If you don't mind we can contact by email. Myemail is "clbhtsvnguyenmanhcuong@gmail.com".
Thank you very much. Have a nice day.

chaos_zzy October 28, 2010 10:50

Quote:

Originally Posted by myyahaha (Post 281050)
Hi Bighead. I appriciate that you answer my question. However I think you maybe misunderstand. I already know how to model an Ansys Model but my question is "how to get information about the heat source?" . How to measure total heat power of an object by someway such as datasheets.. to fill information in Ansys model.
Can you help me please?
If you don't mind we can contact by email. Myemail is "clbhtsvnguyenmanhcuong@gmail.com".
Thank you very much. Have a nice day.

The real power loss (heat) normally need Electronics Engineer to calculate for you. if you konw the real working model of component, you also can calculated by yourself, such as switch frequency, currrent, voltage. Google it there are many formula telling you how to do it for different types of component. Or you can measure it when component working.

myyahaha October 30, 2010 06:14

OK. thank for your help. I think i must ask my tutor. ^^

bighead November 16, 2010 07:43

Sorry for my misunderstanding.

For most packages, there is usually a thermal design power (TDP) for steady state calculation. For transistors, its usually related to the current at the gates (Joule heating). These can be used as a starting point till you get more info from measurements. There are plenty of work done at the device level in thermal modeling. I think your answer can be found in the publications there.

myyahaha November 17, 2010 00:43

Quote:

Originally Posted by bighead (Post 283612)
Sorry for my misunderstanding.

For most packages, there is usually a thermal design power (TDP) for steady state calculation. For transistors, its usually related to the current at the gates (Joule heating). These can be used as a starting point till you get more info from measurements. There are plenty of work done at the device level in thermal modeling. I think your answer can be found in the publications there.

Thanks. However my tutor said that it wasn't a problem because i am engineer and i can allow how many total power i want. :D

chaos_zzy November 17, 2010 09:47

Quote:

Originally Posted by myyahaha (Post 283713)
Thanks. However my tutor said that it wasn't a problem because i am engineer and i can allow how many total power i want. :D

However, in many cases, your enemy Electronic Engineer always want give you more heat.:D


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