Find the efficiency of a pin fin with the following parameters: h = 50- W mK k = 120 W mK L = 2 cm D = 0.1 cm a) Efin = = 0.82 b) fin = = 0.97 c) fin = 9.25 d) fin = 15.2 Can the cylinder described below can be accurately modelled using lumped system analysis? r = 5 cm L = 20 cm p = 2500 kg c = 400 W 3 k = 50 W m h = 45- kgK mK mK = rL = 2rL + 22 Vcyl Acyl a) Yes, the Biot number is sufficiently small b) Yes, the Biot number is sufficiently large c) No, the time constant is too small d) No, the time constant is too large