Chemical Engineering PE Exam Flashcards
6 cards from real NCEES practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Chemical Engineering PE Exam flashcards as text
On the NCEES PE Chemical exam, which equation describes the relationship between mole fractions in vapor-liquid equilibrium for an ideal system (Raoult's law)?
Answer: yi × P = xi × Pi_sat
Raoult's law states that for ideal mixtures, the partial pressure of component i equals its mole fraction in the liquid (xi) times its pure-component vapor pressure (Pi_sat): yi × P = xi × Pi_sat.
In the NCEES PE Chemical exam, what does the 'LMTD' (log mean temperature difference) method calculate in heat exchanger design?
Answer: The effective driving force for heat transfer when temperature difference varies along the exchanger length
LMTD is the logarithmic average of the terminal temperature differences in a heat exchanger, providing the correct mean driving force for calculating required heat transfer area: Q = U × A × LMTD.
For the NCEES PE Chemical exam, what is the 'residence time distribution (RTD)' concept used for in reactor design?
Answer: To characterize mixing behavior and deviation from ideal reactor models in real reactors
RTD analysis (using tracer experiments) characterizes how long different fluid elements spend in a reactor, revealing mixing patterns and deviations from ideal CSTR or PFR behavior.
On the NCEES PE Chemical exam, which dimensionless number characterizes the ratio of convective heat transfer to conductive heat transfer in a fluid?
Answer: Nusselt number
The Nusselt number (Nu = hL/k) is the dimensionless convective heat transfer coefficient, representing the enhancement of heat transfer by convection relative to conduction through the same fluid layer.
In the NCEES PE Chemical exam, what is the 'Fanning friction factor' used to calculate in pipe flow?
Answer: The pressure drop due to friction in a pipe per unit length
The Fanning friction factor f (or Darcy-Weisbach friction factor) is used in the Darcy-Weisbach equation to calculate frictional pressure drop in pipe flow: ΔP = f(L/D)(ρV²/2).
For the NCEES PE Chemical exam, what does 'adiabatic flame temperature' represent in combustion engineering?
Answer: The maximum theoretical temperature achieved when fuel burns completely with no heat loss to surroundings
Adiabatic flame temperature is the theoretical upper limit of combustion temperature calculated from energy balance assuming all heat of combustion heats the products with zero heat loss.
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