EIT Thermodynamics 3

Question 1

In a steady-flow system, the energy equation per unit mass is: h1 + V1²/2 + gz1 + q = h2 + V2²/2 + gz2 + w. For an adiabatic nozzle with negligible elevation change and no work, which simplification applies?

Accepted Answer

h1 + V1²/2 = h2 + V2²/2

Answer

With q = 0, w = 0, and Δz ≈ 0, the energy equation reduces to h1 + V1²/2 = h2 + V2²/2.

Question 2

Which of the following is a valid statement of the second law of thermodynamics?

Accepted Answer

No heat engine can have 100% thermal efficiency

Answer

The Kelvin-Planck statement of the second law prohibits any cyclic device from converting heat entirely to work.

Question 3

For a van der Waals gas, the equation of state is (P + a/v²)(v - b) = RT. The term a/v² accounts for:

Accepted Answer

Intermolecular attractive forces

Answer

The term a/v² corrects for intermolecular attractive forces that reduce the effective pressure.

Question 4

In a Rankine cycle, what component increases the pressure of the working fluid?

Accepted Answer

Pump

Answer

The pump increases the pressure of the liquid condensate from condenser pressure to boiler pressure.

Question 5

For an ideal gas, the internal energy is a function of temperature only. This means that (∂u/∂v)_T equals:

Accepted Answer

0

Answer

For an ideal gas, internal energy depends only on temperature, so (∂u/∂v)_T = 0.

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EIT Thermodynamics 3