How do you calculate fin efficiency and what factors affect it?

Fin efficiency (η_f) is the ratio of actual heat transfer to the heat transfer if the entire fin were at base temperature. For a straight rectangular fin: η_f = tanh(mL)/(mL), where m = √(hP/kA_c), h is convective coefficient, P is perimeter, k is conductivity, and A_c is cross-sectional area. Factors affecting efficiency: high thermal conductivity increases efficiency, longer fins reduce efficiency, higher convective coefficient reduces efficiency, thicker fins are more efficient. Typical efficiencies range from 70-95%. Design optimization balances fin length, material, and geometry for maximum heat dissipation per unit weight.