Two heat transfer questions (fins) I am unsure of

[engineer23]

Homework Statement

A fin is 80% efficient. Which design change would improve the heat transfer the most, assuming all other variables were held
constant?
(a) double the number of fins
(b) double the length of the fins
(c) find a new material with twice the conductivity
(d) double the heat transfer coefficient

Homework Equations

No = 1 - NAf/At (1-Nf), where N is number of fins, Af is area of fin, At is area of primed surface, Nf is efficiency of single fin

Nf = qf/hAf(Tb-T*), where qf is heat transfer rate of fin, Tb is temperature of fin base, and T* is the ambient temperature

The Attempt at a Solution

increasing the number of fins definitely improves the heat transfer rate, but if you add too many the spacing between fins becomes small and flow is impeded

doubling the length of the fins also increases efficiency, but there is an upper limit (2.65/m), where m = sqrt(hP/kAc), beyond which improvement is not very significant

doubling the heat transfer coefficient (h) is not always practical, depending on the power required to force air at velocity v through the system

So I want to say the answer is (c)...?

 

[KataKoniK]

Finding a new material with twice the conductivity would have the greatest impact on improving heat transfer. This is because the heat transfer rate of a fin is directly proportional to the thermal conductivity of the material it is made of (Nf = qf/hAf(Tb-T*)). Therefore, doubling the thermal conductivity of the material would result in a doubling of the heat transfer rate, improving the overall efficiency of the fin. Additionally, finding a material with higher thermal conductivity would not require any changes to the design or added costs for additional fins or increased length.

 

[piercas]

Yes, (c) finding a new material with twice the conductivity would improve the heat transfer the most. This is because the efficiency of a single fin is directly proportional to the conductivity of the material. Therefore, doubling the conductivity would result in a significant increase in efficiency and ultimately improve heat transfer. Additionally, this option does not have any potential limitations or trade-offs like the other options do.