Practice Pakistan's most useful MCQs for competitive exams

Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low___________________?

• (A)  Hardness
• (B)  Dissolved solids content
• (C)  Suspended solids content
• (D)  All

Answer

Submitted By :Ali Uppal

_______________ paint has the maximum absorption coefficient ?

• (A)  Black
• (B)  Yellow
• (C)  White
• (D)  Grey

Answer

Submitted By :Ali Uppal

Baffles are provided in heat exchangers to increase the________________?

• (A)  Fouling factor
• (B)  Heat transfer area
• (C)  Heat transfer co-efficient
• (D)  Heat transfer rate

Answer

Submitted By :Ali Uppal

The rate of heat transfer through a pipe wall is given by, q = 2π k (Ti – T0)/ln (ri/r0). For cylinder of very thin wall, q can be approximated by__________________?

• (A)  q = [2π k (Ti + T0)/2]/ln (ri/r0)
• (B)  q = 2π ri k (Ti – T0)/(r0/ri)
• (C)  q = 2π k (Ti – T0)/(r0/ri)
• (D)  q = 2π k (Ti – T0)/[(r0 + ri)/2]

Answer

Submitted By :Ali Uppal

If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will ________________?

• (A)  Increase by 1.8 times
• (B)  Decrease by 22
• (C)  Increase by 216
• (D)  Remain unchanged

Answer

Submitted By :Ali Uppal

A measure of the extent to which viscous heating is important relative to the heat flow resulting from the impressed temperature difference is represented by the _______________ number?

• (A)  Condensation
• (B)  Grashoff
• (C)  Stanton
• (D)  Brinkman

Answer

Submitted By :Ali Uppal

The Fourier number (defined as a.t/L2) is used in the analysis of problem involving heat transfer by_______________?

• (A)  Forced convection
• (B)  Natural convection
• (C)  Transient conduction
• (D)  Steady state conduction

Answer

Submitted By :Ali Uppal

Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for_________________?

• (A)  Cube
• (B)  Cylinder
• (C)  Sphere
• (D)  Equal for all the three

Answer

Submitted By :Ali Uppal

Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids ?

• (A)  Dittus-Boelter equation
• (B)  Sieder-Tate equation
• (C)  Nusselt equation
• (D)  None of these

Answer

Submitted By :Ali Uppal

For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then__________________?

• (A)  hf = hd
• (B)  hf > hd
• (C)  hf < hd
• (D)  hf could be greater or smaller than hd

Answer

Submitted By :Ali Uppal