At steady state, air at 200 kPa, 51.85C and a mass flow rate of 4.02 kg/s enters an insulated duct having differing inlet and exit cross-sectional areas. At the duct exit, the pressure of the air is 100 kPa, the temperature is 82C, the velocity is 255 m/s, and the cross-sectional area is 2 x 10-3 m. Assuming the ideal gas model, determine the rate of entropy production within the duct, in W/K.