A submarine is to be designed to provide a comfortable temperature for the crew of no less than 21°C. The submarine can be idealized by a cylinder 9 m in diameter and 61 m in length. The combined heat transfer coefficient on the interior is about 14 W/(m2K), while on the outside the heat transfer coefficient is estimated to vary from about 57 W/(m2K) (not moving) to 847 W/(m2K) (top speed). The sea water temperatures vary from 1.1 to 12.8°C during operation. For the construction of the wall, three different options need to be evaluated. 

(a) 2 cm aluminium

(b) 1.8 cm stainless steel with a 2.5 cm thick layer fiberglass insulation on the inside and

(c) sandwich construction with a 1.8 cm thickness of stainless steel, a 2.5 cm thick layer of fiberglass insulation, and a 0.6 cm thickness of aluminium on the inside. Determine the best option for the construction of the submarine.