Chemical Engineering - MCQ Practice Questions

Which of the following is the SI unit of thermal conductivity?

In heat conduction through a composite wall, the overall heat transfer rate is determined by which principle?

Which dimensionless number represents the ratio of buoyancy forces to viscous forces in natural convection?

Which of the following best describes the behavior of thermal conductivity with temperature for most metals?

The thermal diffusivity (α) has dimensions of which of the following?

The Biot number (Bi) is defined as the ratio of which resistances in transient heat conduction?

The Fourier number (Fo = αt/L²) in unsteady-state conduction represents the ratio of:

The Stefan-Boltzmann constant (σ) has SI units of:

The Rayleigh number (Ra) in natural convection is defined as Ra = Gr·Pr. When Ra < 10⁹ for vertical surfaces, the heat transfer is primarily:

The dimensionless Stanton number (St = h/(ρ·v·c_p)) in heat transfer represents:

In a parallel flow heat exchanger, hot fluid enters at 80°C and exits at 50°C while cold fluid enters at 20°C and exits at 40°C. Calculate the Log Mean Temperature Difference (LMTD).

Which of the following dimensionless numbers is used to predict the transition from laminar to turbulent flow in forced convection?

In the context of thermal radiation, the Stefan-Boltzmann constant has a value of:

A horizontal cylindrical pipe carries hot water at 80°C through ambient air at 20°C. The convective heat transfer coefficient is 25 W/m²·K and pipe diameter is 50 mm. Calculate heat loss per unit length if the pipe is not insulated.

Which of the following materials would be most suitable for a heat sink application requiring high thermal conductivity and low cost?

In a shell-and-tube heat exchanger, what is the primary advantage of using baffles?

The Nusselt number (Nu) relationship for laminar flow in a circular pipe is given by Nu = 3.66. What does this value represent?

In radiation heat transfer, the Stefan-Boltzmann constant σ has a value of 5.67 × 10⁻⁸ W/(m²·K⁴). A black body at 500 K radiates heat. If the temperature is doubled to 1000 K, by what factor does the radiated heat increase?

A flat-plate solar collector has a black absorber plate maintained at 80°C. The ambient temperature is 20°C and the heat loss coefficient (overall U value including radiation and convection) is 8 W/(m²·K). For a collector area of 4 m², what is the heat loss rate to the surroundings?

What is the SI unit of thermal conductivity?