An insulated storage tank contains 1000 kg liquid of specific heat 10 kJ kg-1 K-1. The liquid is heated by saturated steam

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