3. Air flows through a long duct of constant area at 0.15 kg/sec. A short section of the duct is cooled by liquid nitrogen that surrounds the duct. The rate of heat loss in this section is 15.0 kJ/sec from the air. The absolute pressure, temperature and velocity entering the cooled section are 188 kPa, 440 K and 210 m/sec, respectively. At the outlet, the absolute pressure and temperature are 213 kPa and 351 K. Find the duct cross-sectional area and the changes in enthalpy, internal energy and the entropy for the flow. Section 1 Section 2 P₁=188 kPa P₂=213 kPa T₁=440 K V₁ =210 m/sec T₂=351 K