NCEES Chemical Engineering PE Exam

Question 1

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)?

Accepted Answer

yi × P = xi × Pi_sat

Answer

yi = xi × Ki where Ki = Hi / P

Answer

yi / xi = exp(A/T)

Answer

P_total = Σ(xi × Hi)

Question 2

In the NCEES PE Chemical exam, what does the 'LMTD' (log mean temperature difference) method calculate in heat exchanger design?

Accepted Answer

The effective driving force for heat transfer when temperature difference varies along the exchanger length

Answer

The maximum operating temperature of the heat exchanger

Answer

The log-scale pressure drop across the tube bundle

Answer

The ratio of hot to cold fluid flow rates

Question 3

For the NCEES PE Chemical exam, what is the 'residence time distribution (RTD)' concept used for in reactor design?

Accepted Answer

To characterize mixing behavior and deviation from ideal reactor models in real reactors

Answer

To determine the startup time for a batch reactor

Answer

To calculate the recycle ratio in distillation columns

Answer

To measure heat removal from exothermic reactors

Question 4

On the NCEES PE Chemical exam, which dimensionless number characterizes the ratio of convective heat transfer to conductive heat transfer in a fluid?

Accepted Answer

Nusselt number

Answer

Reynolds number

Answer

Prandtl number

Answer

Grashof number

Question 5

In the NCEES PE Chemical exam, what is the 'Fanning friction factor' used to calculate in pipe flow?

Accepted Answer

The pressure drop due to friction in a pipe per unit length

Answer

The drag force on particles settling in a fluid

Answer

The heat transfer enhancement in turbulent flow

Answer

The pump efficiency at off-design conditions

Question 6

For the NCEES PE Chemical exam, what does 'adiabatic flame temperature' represent in combustion engineering?

Accepted Answer

The maximum theoretical temperature achieved when fuel burns completely with no heat loss to surroundings

Answer

The minimum temperature for ignition of the fuel-air mixture

Answer

The temperature of the exhaust gas after heat recovery

Answer

The autoignition temperature listed in safety data sheets