Chemical Engineering - MCQ Practice Questions

In heat exchanger design for petrochemical plants, fouling resistance (Rf) is critical. For a crude oil preheater, the typical internal fouling resistance is 0.0005 m²·K/W. If the design duty is 5 MW, what is the maximum temperature difference loss due to fouling on a surface area of 100 m²?

The thermal entrance length for laminar flow in a pipe is given by x_th/D ≈ 0.05·Re·Pr. For water flowing in a 25 mm diameter pipe with Reynolds number of 1000 and Prandtl number of 7, what is the thermal entrance length?

In a parallel-flow heat exchanger with hot inlet temperature Th,in = 100°C, cold inlet temperature Tc,in = 30°C, and hot outlet temperature Th,out = 60°C, what is the hot fluid capacity rate ratio if the cold outlet temperature is 50°C?

The Colburn factor (j) for heat transfer is related to the Nusselt number. For turbulent flow over a flat plate, the typical correlation is j ≈ 0.037·Re^(-0.2). What does the Colburn factor represent?

In the design of a heat recovery steam generator (HRSG) for a combined cycle power plant, the approach temperature is 5°C. If the exhaust gas inlet temperature is 450°C and the approach temperature represents the difference between exhaust gas exit and steam outlet temperatures, what is the steam outlet temperature?

The effectiveness-NTU (Number of Transfer Units) method is preferred over LMTD method when designing heat exchangers because:

For turbulent flow in a rough pipe, the friction factor is determined by both Reynolds number and relative roughness (ε/D). According to the Moody chart, in the complete turbulence zone, the friction factor becomes independent of:

The Peclet number (Pe = Re·Pr) is used to determine the relative importance of convection to conduction. For Pe << 1, which heat transfer mechanism is dominant?

A shell-and-tube heat exchanger with one shell pass and two tube passes (1-2 STHE) has a correction factor F. What is the typical range of F values?

In convective heat transfer, which dimensionless number represents the ratio of buoyant to viscous forces?

For radiation heat transfer between two surfaces, increasing the absolute temperature of the hot surface by 10% will increase radiative heat transfer by approximately what percentage?

The overall heat transfer coefficient U in a composite system (series resistances) is determined by which method?

In pool boiling, the critical heat flux (CHF) occurs at which point on the boiling curve?

The Prandtl number (Pr = Cp·μ/k) represents the ratio of which two transport properties?

In a multipass heat exchanger design, increasing the number of shell passes from 1 to 2 will predominantly affect which parameter?

For turbulent flow in rough pipes at high Reynolds numbers, which friction factor equation is most applicable?

Water flows through a venturimeter with inlet diameter 0.1 m and throat diameter 0.05 m. The pressure difference is 5 kPa. Assuming ideal flow, calculate the velocity at the inlet (ρ = 1000 kg/m³).

Which type of pump is most suitable for high-head, low-flow applications?

What is the relationship between Fanning friction factor (f) and Darcy friction factor (fD)?

In a packed bed, if particle diameter increases while maintaining constant bed porosity and superficial velocity, the pressure drop will: