A gas is heated in a duct as it flows over a resistance heater. Consider a 101 kW electric heating system. The gas enters the heating section of the duct at 100 kPa and 27 ºC with a volume flow rate

Q. A gas is heated in a duct as it flows over a resistance heater. Consider a 101 kW electric heating system. The gas enters the heating section of the duct at 100 kPa and 27 ºC with a volume flow rate of 15 m³/s. If heat is lost from the gas in the duct to the surroundings at a rate of 51 kW, the exit temperature of the gas is (Assume constant pressure, ideal gas, negligible change in kinetic and potential energies and constant specific heat; Cp = 1 kJ/kg·K; R = 0.5 kJ/kg·K.)

             (A) 32 ^oC           (B) 37 ^oC                    (C) 53 ^oC                   (D) 76 ^oC

Ans:32 ^oC  

Sol: