Thermodynamics Flashcards
7 cards from real BME practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Thermodynamics flashcards as text
Which thermodynamic process occurs at constant entropy?
Answer: Isentropic
An isentropic process is reversible and adiabatic, meaning entropy remains constant throughout.
The Clausius inequality states that for any cycle, the cyclic integral of δQ/T is:
Answer: Less than or equal to zero
The Clausius inequality states ∮(δQ/T) ≤ 0, with equality holding only for reversible cycles.
In a Brayton cycle, increasing the compressor pressure ratio (up to the optimal value) generally:
Answer: Increases thermal efficiency
Higher pressure ratio increases the thermal efficiency of the Brayton cycle because more compression raises the average temperature of heat addition.
For an ideal gas undergoing a polytropic process PVⁿ = C, if n equals the ratio of specific heats γ, the process is:
Answer: Isentropic
When n = γ (= Cp/Cv), the polytropic process becomes isentropic (reversible adiabatic).
The coefficient of performance (COP) of a heat pump is related to COP of a refrigerator operating between the same temperatures by:
Answer: COP_HP = COP_R + 1
COP_HP = COP_R + 1, because the heat pump delivers both the heat removed from the cold reservoir plus the work input.
Which statement correctly describes the Joule-Thomson effect for an ideal gas?
Answer: Temperature remains unchanged during throttling
For an ideal gas, the Joule-Thomson coefficient is zero, so throttling causes no temperature change.
The exergy (availability) of a system at the dead state is:
Answer: Zero
At the dead state (equilibrium with the environment), a system has zero exergy because no work can be extracted from it.