An electric heating coil is immersed in a stirred tank. The shaft work of the stirrer is 560 W. A solvent at 15 C with heat capacity of 2.1J/g C is fed into the tank at 15 kg/h. Heated solvent is discharged, simultaneously, at the same flow rate. The tank is filled initially with 125 kg cold solvent at 10 C. The heating rate of the electric coil is 2.0 kW. Calculate the time required for the temperature of the solvent to reach 60 C.