Chapter 7, Problem 3P

A gas mixture with a molar analysis of 40% CH4 (methane) and 60% air enters a control volume operating at steady state at location 1 with a mass flow rate of 5 kg/min, as shown in the figure below. Air enters as a separate stream at 2 and dilutes the mixture. A single stream exits with a mole fraction of methane of 5%. Assume air has a molar analysis of 21% O2 and 79% N2. (CH4, Air) m₁ = = 5 kg/min Air (21% O2, 79% N₂) 3 + (5% CH4, 95% Air)

Argon (Ar), at T₁ = 350 K, 1 bar with a mass flow rate of m₁ 3 kg/s enters the insulated mixing chamber shown in the figure below and mixes with carbon dioxide (CO2) entering as a separate stream at 575 K, 1 bar with a mass flow rate of 0.5 kg/s. The mixture exits at 1 bar. Assume ideal gas behavior with k = 1.67 for Ar and k = 1.25 for CO2. Argon (Ar) P₁ = 1 bar mT For steady-state operation, determine: (a) the molar analysis of the exiting mixture. (b) the temperature of the exiting mixture, in K. (c) the rate of entropy production, in kW/K. Insulation 3 + Mixture exiting P3 = 1 bar 2+ Carbon dioxide (CO2) T₂ = 575 K P2 = 1 bar m2 = 0.5 kg/s

Consider 0.65 kg of N2 at 300 K, 1 bar contained in a rigid tank connected by a valve to another rigid tank holding 0.3 kg of CO2 at 300 K, 1 bar. The valve is opened and gases are allowed to mix, achieving an equilibrium state at 290 K. Determine: (a) the volume of each tank, in m³. (b) the final pressure, in bar. (c) the magnitude of the heat transfer to or from the gases during the process, in kJ. (d) the entropy change of each gas and of the overall system, in kJ/K.