Chapter 6, Problem 6.72P

Air expands adiabatically in a piston–cylinder assembly from an initial state where p1 = 100 lbf/in.2, v1 = 3.704 ft3/lb, and T1 = 1000 °R, to a final state where p2 = 20 lbf/in.2 The process is polytropic with n = 1.4. The change in specific internal energy, in Btu/lb, can be expressed in terms of temperature change as Δu=(0.171)(T2 - T1).Determine the final temperature, in °R.Kinetic and potential energy effects can be neglected.

6.72 WP Figure P6.72 shows data for a portion of the ducting in a ventilation system operating at steady state. The ducts are well in- sulated and the pressure is very nearly 1 atm throughout. Assuming the ideal gas model for air with c, = 0.24 Btu/lb · °R, and ignoring kinetic and potential energy effects, determine (a) the temperature of the air at the exit, in °F, (b) the exit diameter, in ft, and (c) the rate of entropy production within the duct, in Btu/min· °R. %3D D = 4 ft V = 400 f/min T = 80°F page2 3 V= 400 ft/min T3 = ? D3 = ? Insulation = 2000 ft/min (AV)2 V2 = 600 f/min T2 = 40°F

The figure shows data for a portion of the ducting in a ventilation system operating at steady state. The ducts are well insulated and the pressure is very nearly 1 atm throughout. The volumetric flow rate entering at state 2 is AV2 = 2000 ft3/min. Assume the ideal gas model for air with c, = 0.24 Btu/lb-°R and ignore kinetic and potential energy effects. (AV)1 = 5000 ft/min 1 Air, Cp = 0.24 Btu/lb°R T = 80°F p=1 atm 3 V3 = 400 ft/min T3 = ? Insulation ft/min (AV)2 Tz = 40°F Determine the temperature of the air at the exit, in °F, and the rate of entropy production within the ducts, in Btu/min.°R.

The figure shows data for a portion of the ducting in a ventilation system operating at steady state. The ducts are well insulated and the pressure is very nearly 1 atm throughout.  The volumetric flow rate entering at state 2 is AV2 = 4000 ft3/min.  Assume the ideal gas model for air with cp = 0.24 Btu/lb·oR and ignore kinetic and potential energy effects.  Determine the temperature of the air at the exit, in oF, and the rate of entropy production within the ducts, in Btu/min·oR.

The figure shows data for a portion of the ducting in a ventilation system operating at steady state. The ducts are well insulated and the pressure is very nearly 1 atm throughout. The volumetric flow rate entering at state 2 is AV2 = 2800 ft³/min. Assume the ideal gas model for air with c, = 0.24 Btu/lb•°R and ignore kinetic and potential energy effects. 1 (AV)1 = 5000 ft /min Air, Co = 0.24 Btu/lb°R T, = 80°F p=1 atm 3 V3 = 400 ft/min T3 = ? 2 (AV)2 Tz = 40°F -Insulation ft/min Determine the temperature of the air at the exit, in °F, and the rate of entropy production within the ducts, in Btu/min-°R.

The figure shows data for a portion of the ducting in a ventilation system operating at steady state. The ducts are well insulated and the pressure is very nearly 1 atm throughout. The volumetric flow rate entering at state 2 is AV2 = 2000 ft/min. Assume the ideal gas model for air with c, = 0.24 Btu/I6•°R and ignore kinetic and potential energy effects. (AV)1 = 5000 ft³/min Air, Cp = 0.24 Btu/lb°R 1 T = 80°F p=1 atm 3 V3 = 400 ft/min T3 = ? Insulation ft/min (AV)2 T2 = 40°F Determine the temperature of the air at the exit, in °F, and the rate of entropy production within the ducts, in Btu/min-°R.

A fixed-mass system contains mass, m = 1.0 kg of air. A thermodynamic process occurs from state one to state two, where T₁ = 300 °K, P₁ = 100 kPa; T₂ = 2700 °K, P₂ = 204.9953251 kPa. Determine S₂ - S₁ = m (S₂-S₁) in kJ / °K. Note: You are required to assume constant specific heats in this problem, with Cpo = 1.004 kJ/(°K * kg); for air, the gas constant is R = 0.287 kJ/(°K * kg).

An oil pump operating at steady state delivers oil at a rate of 11 lb/s through a 1-in.-diameter exit pipe. The oil, which can be modeled as incompressible, has a density of 70 Ib/ft³ and experiences a pressure rise from inlet to exit of 40 Ibf/in?. There is no significant elevation difference between inlet and exit, and the inlet kinetic energy is negligible. Heat transfer between the pump and its surroundings is negligible, and there is no significant change in temperature as the oil passes through the pump. Determine the velocity of the oil at the exit of the pump, in ft/s, and the power required for the pump, in hp.

Thermo 12