ME or MEng Master of Engineering Thermodynamics and Heat Transfer 2

Question 1

The effectiveness-NTU method in heat exchanger analysis defines effectiveness as:

Accepted Answer

Ratio of actual heat transfer to maximum possible heat transfer

Answer

Effectiveness ε = Q_actual / Q_max, where Q_max is the heat transferred if one fluid underwent the maximum possible temperature change.

Question 2

In the Rankine cycle used in steam power plants, which component increases the pressure of the working fluid?

Accepted Answer

Pump

Answer

The pump raises the pressure of the condensate from condenser pressure to boiler pressure, requiring work input.

Question 3

Stefan-Boltzmann Law states that thermal radiation emitted by a blackbody is proportional to:

Accepted Answer

T⁴

Answer

A blackbody emits radiation q = σT⁴, where σ is the Stefan-Boltzmann constant (5.67 × 10⁻⁸ W/m²K⁴).

Question 4

Superheat in a Rankine cycle is added primarily to:

Accepted Answer

Increase turbine efficiency and reduce moisture content

Answer

Superheating raises the turbine inlet temperature, increasing cycle efficiency and reducing moisture that erodes turbine blades.

Question 5

The Biot number in heat transfer is defined as:

Accepted Answer

hL/k, ratio of convective to conductive resistance

Answer

Bi = hL_c/k compares internal conductive resistance (L_c/k) to external convective resistance (1/h) for a solid body.

ME or MEng Master of Engineering Practice Test