15. At a given point in a thin-walled heat exchanger, the shell-side fluid is at 100C and the tube side fluid is at 20C. Ignoring any fouling resistances and the resistance of the wall, determine the wall temperature for the following cases: a. The inside and outside heat transfer coefficients are equal. b. The inside coefficient has a value 3 times that of the outside coefficient. c. The inside coefficient has a value 1/3 that of the outside coefficient. d. The inside coefficient is limiting