Thank you in advance An electronic chip 48 mm by 48 mm dissipates 25 W and is co

Question

Thank you in advance

An electronic chip 48 mm by 48 mm dissipates 25 W and is cooled by air (25 degree C). Reliability and life of chip can be improved if the surface temperature is lowered. This can be achieved by adding a finned heat sink to increase the surface area for convective heat transfer. For (a) determine the surface temperature of the chip for the unfinned configuration with a convective heat transfer coefficient of 200 W/m2.K. For (b) determine the surface temperature if a copper finned heat sink is attached with 8 equally spaced fins (2mm thick, 20 mm high and 48 mm long) are attached to the chip. The convective heat transfer coefficient is reduced to 150 W/m2.K due to fins.

Explanation / Answer

I am writing here how to solve this problem, but i can't solve now as i don't have my calculator with me rite now... really sorry for that.

(a) We know, for convective heat transfer,
E=h*A*(t-T)
where E=25 W

h= convective heat transfer coefficient=200 W/m^2.K
A= surface area=48*48 mm^2
t= surrounding temperature= 25 deg C
Solve to get T

(b) Everything remains same as (a), only h and A changes.
Here, h=150 W/m^2.K

A=(48*48)+(16*(20*48))+(16*(20*2)) mm^2
solve to get T

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