Chapter 6, Problem 6.88P

Refrigerant 134a enters an insulated diffuser as a saturated vapor at 60oF with a velocity of 1000 ft/s. The inlet area is 1.4 in2. At the exit, the pressure is 400 lbf/in2 and the velocity is negligible. The diffuser operates at steady state and potential energy effects can be neglected.Determine the mass flow rate, in lb/s, and the exit temperature, in oF.

Refrigerant 134a enters an insulated diffuser as a saturated vapor at 80oF with a velocity of 1200 ft/s. The inlet area is 1.4 in2.  At the exit, the pressure is 400 lbf/in2 and the velocity is negligible. The diffuser operates at steady state and potential energy effects can be neglected. Determine the mass flow rate, in lb/s, and the exit temperature, in oF.

One can store energy by compressing air and use it later to power a turbine to create energywhen needed. The air must be heated to make this effective, which can be accomplished by compressing the air under adiabatic conditions. This is called adiabatic compressed air energy storage (CAES). Inside a typical power plant, 5.8×10^6 kg of N2 gas is at 25 °C is compressed from atmospheric to pressure into a volume of 300,000 m3 (they use abandoned salt mines). The process is done reversibly and adiabatically. What is q, n, Vi, Pf, T, U,w, and H and for this process? (Cp,m = 29.12 J/K/mol and Cv,m = 20.80 J/K/mol for N2). Assume perfect gas behavior.

Carbon dioxide gas is compressed at a steady state from a pressure of 16 lbf/in2 and a temperature of 32oF to a pressure of 50 lbf/in2 and a temperature of 130oF. The gas enters the compressor with a velocity of 30 ft/s and exits with a velocity of 80 ft/s. The mass flow rate is 3500 lb/hr. The magnitude of the heat transfer rate from the compressor to its surroundings is 5% of the compressor power input. Use the ideal gas model with cp = 0.21 Btu/lb·oR and neglect potential energy effects. A.) Determine the flow area at the inlet, in ft2, B.) and the power required by the compressor to work, in horsepower. Show complete solutions.

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Steam enters a turbine operating at steady state at 850oF and 450 lbf/in2 and leaves as a saturated vapor at 1.4 lbf/in2. The turbine develops 12,000 hp, and heat transfer from the turbine to the surroundings occurs at a rate of 2 x 106 Btu/h. Neglect kinetic and potential energy changes from inlet to exit. Determine the exit temperature, in oF, and the volumetric flow rate of the steam at the inlet, in ft3/s.

A pump is used to circulate hot water in a home heating system. Water enters the well-insulated pump operating at steady state at a rate of 0.42 gal/min. The inlet pressure and temperature are 14.7 Ibf/in.², and 180°F, respectively; at the exit the pressure is 120 Ibf/in.2 The pump requires 1/ 15 hp of power input. Water can be modeled as an incompressible substance with constant density of 60.58 Ib/ft3 and constant specific heat of 1 Btu/lb · °R. Neglecting kinetic and potential energy effects, determine the temperature change, in °R, as the water flows through the pump. AT = i °R

Water contained in a closed, rigid tank, initially at 100 lbf/in2, 800oF, is cooled to a final state where the pressure is 20 lbf/in2.Determine the quality at the final state and the change in specific entropy, in Btu/lb·oR, for the process.