Q. An insulated storage tank contains 1000 kg liquid of specific heat 10 kJ kg-1 K-1. The liquid is heated by saturated steam, condensing in a helical coil at a temperature of 180 oC. The heat transfer area of the coil is 0.1 m2. If the overall heat transfer coefficient is constant at 1000 W m-2 K-1, then the time (in hours) required to raise the temperature of the liquid in the tank from 20 oC to 80 oC is
Ans: 12.75 to 13.25