Thermodynamics and Heat Transfer Flashcards
6 cards from real ME or MEng Master of Engineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Thermodynamics and Heat Transfer flashcards as text
The effectiveness-NTU method in heat exchanger analysis defines effectiveness as:
Answer: Ratio of actual heat transfer to maximum possible heat transfer
Effectiveness ε = Q_actual / Q_max, where Q_max is the heat transferred if one fluid underwent the maximum possible temperature change.
In the Rankine cycle used in steam power plants, which component increases the pressure of the working fluid?
Answer: Pump
The pump raises the pressure of the condensate from condenser pressure to boiler pressure, requiring work input.
Stefan-Boltzmann Law states that thermal radiation emitted by a blackbody is proportional to:
Answer: T⁴
A blackbody emits radiation q = σT⁴, where σ is the Stefan-Boltzmann constant (5.67 × 10⁻⁸ W/m²K⁴).
Superheat in a Rankine cycle is added primarily to:
Answer: Increase turbine efficiency and reduce moisture content
Superheating raises the turbine inlet temperature, increasing cycle efficiency and reducing moisture that erodes turbine blades.
The Biot number in heat transfer is defined as:
Answer: hL/k, ratio of convective to conductive resistance
Bi = hL_c/k compares internal conductive resistance (L_c/k) to external convective resistance (1/h) for a solid body.
In a refrigeration cycle, the Coefficient of Performance (COP) is defined as:
Answer: Heat removed from the cold space divided by work input
COP_refrigerator = Q_L / W_net, measuring how much heat is removed per unit of work input.