ME or MEng Master of Engineering Thermodynamics and Heat Transfer 3

Question 1

Which heat transfer mode does NOT require a medium (can occur in a vacuum)?

Accepted Answer

Radiation

Answer

Thermal radiation is electromagnetic energy transfer that requires no medium, allowing heat transfer across a vacuum.

Question 2

In a gas turbine (Brayton) cycle, the ideal thermal efficiency depends on:

Accepted Answer

Pressure ratio

Answer

Brayton cycle efficiency η = 1 − r_p^((1−γ)/γ), depending only on the pressure ratio r_p and the specific heat ratio γ.

Question 3

The first law of thermodynamics applied to an open steady-flow system is expressed as:

Accepted Answer

Q − W_s = Δh + ΔKE + ΔPE

Answer

For steady-flow open systems, the energy balance per unit mass is Q − W_s = Δh + ΔKE + ΔPE (shaft work, enthalpy, kinetic and potential energy changes).

Question 4

A fin on a heat sink increases heat dissipation primarily by:

Accepted Answer

Increasing the surface area for convection

Answer

Fins extend surface area available for convective heat transfer, increasing the rate of heat dissipation from the base surface.

Question 5

Exergy (availability) in thermodynamics represents:

Accepted Answer

Maximum useful work obtainable relative to the environment

Answer

Exergy is the maximum theoretical work that can be extracted as a system comes to equilibrium with its surroundings.

ME or MEng Master of Engineering Practice Test

ME or MEng Master of Engineering Practice Test

ME or MEng Master of Engineering Thermodynamics and Heat Transfer 3