At Wray and Nephew large volumes of hot water are stored in tanks. There is currently an issue with the main storage tank which is 80 cm in diameter and 2 .0 111 high and contains water at 80C. The tank is 95. percent full. and insulation is to be added so that the 1water temperature will not drop more than 2'C' per hour. a. Derive a relation for the critical radius of insulation for a cylindrical tank b. Specify an insulating material and calculate the thickness required for the specied cooling rate