Consider the following statements pertaining to large heat transfer rate using fins
1. Fins should be used on the side where heat transfer coefficient is small.
2. Long and thick fins should be used.
3. Short and thin fins should be used.
4. Thermal conductivity of fin material should be large.
Which of the following statements are correct?

Correct option is B

· Fins increase the effective surface area. When the convective heat transfer coefficient h is small (e.g., air side), the thermal resistance of convection is large and adding area via fins is most beneficial. On the side where h is already large (e.g., liquid cooling with high h), fins give little incremental benefit.
· Short, thin fins maintain higher fin efficiency, allowing more fins to be placed in a given space (e.g., in heat exchangers, car radiators, electronic heat sinks). This increases effective area without significant conduction losses.
· A high thermal conductivity k reduces axial temperature drop in the fin, improves fin efficiency, and allows heat produced at the base to be conducted to the fin surfaces more effectively. That is why aluminum and copper are common fin materials.