Heat is to be provided to a small room with the finned heater sketched in Fig. P.4.1. Circulating hot oil keeps the base of the fins at 140°F. The fins are made of iron with k = 40 BTU/h ft °F, and the convective heat transfer coefficient is h = 10 BTU/h ft² °F. The room air is at 65°F and can be considered to be well mixed. The room loses heat to the surroundings at the rate of 6,500 BTU/h. Determine the thermal efficiency of the fins in the heater, the fin tip temperature, and the number of fins required.

FIGURE P.4.1:

Transcribed Image Text:

12in. -5in. 2 in. 0.5 in. fin thickness