Thermo Final Exam Energy Balances

Question 1

• Wcv = 0
• If the change in potential energy from inlet to exit is negligible, g(z1 - z2) drops out.
• If the heat transfer with surroundings is negligible, Qcv drops out.

Answer 1

Nozzle / Diffuser

Question 2

• If the change in kinetic energy of flowing matter is negligible, ½(V1^2 - V2^2) drops out.
• If the change in potential energy of flowing matter is negligible, g(z1 - z2) drops out.
• If the heat transfer with surroundings is negligible, Qcv drops out.

Answer 2

Turbine

Question 3

• If the change in kinetic energy of flowing matter is negligible, ½(V1^2 - V2^2) drops out.
• If the change in potential energy of flowing matter is negligible g(z1 - z2) drops out.
• If the heat transfer with surroundings is negligible, Qcv drops out.

Answer 3

Compressor / Pump

Question 4

• Wcv = 0
• If the kinetic energies of the flowing streams are negligible, such that mi(Vi^2 / 2) and me(Ve^2 / 2) drop out.
• If the potential energies of the flowing steams are negligible, such that migzi and megze drop out.
• If the heat transfer with surroundings is negligible, Qcv drops out.

Answer 4

Heat Exchanger

Question 5

• Wcv = 0
• If the change in kinetic energy of the flowing matter upstream and downstream of the restriction is negligible, ½(V1^2 - V2^2) drops out.
• If the change in potential energy of flowing matter is negligible, g(z1 - z2) drops out.
• If the heat transfer with surroundings is negligible, Qcv drops out.

Answer 5

Throttling Device