Q: An insulated piston–cylinder device initially contains 300 L of air
An insulated piston–cylinder device initially contains 300 L of air at 120 kPa and 17°C. Air is now heated for 15 min by a 200-W resistance heater placed inside the cylinder. The pressure of air is ke...
See AnswerQ: A piston–cylinder device contains 0.75 kg of nitrogen
A piston–cylinder device contains 0.75 kg of nitrogen gas at 140 kPa and 37°C. The gas is now compressed slowly in a polytropic process during which PV1.3 = constant. The process ends when the volume...
See AnswerQ: When a system is adiabatic, what can be said about the
When a system is adiabatic, what can be said about the entropy change of the substance in the system?
See AnswerQ: Reconsider Prob. 8–79. Using appropriate software, investigate
Reconsider Prob. 8–79. Using appropriate software, investigate the effect of varying the polytropic exponent from 1 to 1.4 on the entropy change of the nitrogen. Show the processes on a common P-v dia...
See AnswerQ: A mass of 25 lbm of helium undergoes a process from an
A mass of 25 lbm of helium undergoes a process from an initial state of 50 ft3/lbm and 60°F to a final state of 20 ft3/lbm and 240°F. Determine the entropy change of helium during this process, assumi...
See AnswerQ: One kg of air at 200 kPa and 127°C is
One kg of air at 200 kPa and 127°C is contained in a piston–cylinder device. Air is now allowed to expand in a reversible, isothermal process until its pressure is 100 kPa. Determine the amount of he...
See AnswerQ: An insulated rigid tank is divided into two equal parts by a
An insulated rigid tank is divided into two equal parts by a partition. Initially, one part contains 12 kmol of an ideal gas at 330 kPa and 50°C, and the other side is evacuated. The partition is now...
See AnswerQ: Air at 27°C and 100 kPa is contained in a
Air at 27°C and 100 kPa is contained in a piston–cylinder device. When the air is compressed adiabatically, a minimum work input of 1000 kJ will increase the pressure to 600 kPa. Assuming air has con...
See AnswerQ: Air at 3.5 MPa and 500°C is expanded
Air at 3.5 MPa and 500°C is expanded in an adiabatic gas turbine to 0.2 MPa. Calculate the maximum work that this turbine can produce in kJ/kg.
See AnswerQ: Air is compressed in a piston–cylinder device from 90 kPa
Air is compressed in a piston–cylinder device from 90 kPa and 20°C to 600 kPa in a reversible isothermal process. Determine (a) the entropy change of air and (b) the work done.
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