All Free Chemical Engineering MCQs with Answers

• A. Orifice
• B. Segmental
• C. Disk and ring
• D. Independent of the type of

Explanation: Orifice baffles force the shell-side stream through restricted openings, producing strong jetting and the greatest pressure loss among the…

• A. 1/2 and 8
• B. 1/64 and 1/8
• C. 1/8 and 1/64
• D. 1/2 and 5

Explanation: The usual tube-sheet hole groove dimensions are about 1/8 inch in width and 1/64 inch in depth.

• A. It makes condenser compact
• B. More thinner tubes can be used
• C. Pressure drop is reduced
• D. It reduces heat transfer area

Explanation: Using multiple tube-side passes increases the cooling-water velocity and therefore the tube-side heat-transfer coefficient, reducing the…

• A. Hold baffle in space
• B. Fix the tubes in position
• C. Account for thermal strain
• D. None of these

Explanation: Tie rods run through the tube bundle and maintain the spacing of the segmental baffles, usually together with spacer tubes.

• A. 0.01 to 1
• B. 1.5 to 2.5
• C. 5 to 10
• D. 10 to 20

Explanation: Rotary dryers are generally designed economically for a modest number of heat-transfer units, about 1.5 to 2.5.

• A. Tube dia is 3-6 cms, while tube length in 3-6 metres
• B. Steam is fed to the shell, whereas the liquor is filled inside the tube
• C. None of these
• D. Liquor level is maintained at 1/3rd to 1/2 of the height of the tube

Explanation: All three statements describe normal features of a long-tube vertical evaporator: steam is outside the tubes, liquor flows inside them…

• A. 4(0.86P2 - πd2/4)/πd
• B. (P2 - πd2/4)/πd
• C. 4(0.86P2 - πd2)/πd
• D. (4P2 + πd2/4)/πd

Explanation: Equivalent diameter is four times the flow area divided by the wetted perimeter.

• A. Reducing scale deposition
• B. Creating turbulence
• C. Fixing the tubes
• D. Increasing pressure drop

Explanation: Shell-side baffles force the fluid to flow across the tubes rather than straight along the shell, increasing mixing and turbulence and…

• A. Equal to
• B. Four times
• C. Twice
• D. Half

Explanation: Segmental baffles must be stiff enough to support the tube bundle and resist vibration, so their thickness is commonly about twice the…

• A. Triangular pitch
• B. Square pitch
• C. Diagonal square pitch
• D. Heat transfer rate is independent of tube arrangement

Explanation: Triangular pitch packs more tubes into a given shell area and produces stronger shell-side turbulence, giving a higher heat-transfer rate…

• A. (kcal/hr.m2.°C)-1
• B. (BTU/hr.ft2. °F)-1
• C. (W/m2.°K)-1
• D. (kcal/hr. m. °C)-1

Explanation: A cooling-water fouling resistance is commonly about 0.001 to 0.003 hr·ft²·°F/Btu, representing the added resistance caused by deposits on…

• A. Half
• B. Twice
• C. Thrice
• D. Five times

Explanation: For comparable conditions, condensate drains more effectively from a horizontal tube surface and the condensation coefficient is commonly…

• A. Heat transfer co-efficient is proportional to 0.8th power
• B. Pressure drop is proportional to the square
• C. Neither A. nor B.
• D. Both A. & B.

Explanation: For turbulent flow in the tube side, the heat-transfer coefficient commonly varies approximately as mass velocity to the 0.8 power, while…

• A. 4 to 8
• B. 3 to 5
• C. 2 to 3
• D. 6 to 12

Explanation: For liquid shell-and-tube heat exchangers, a tube length several times the shell diameter is preferred for economical design and…

• A. hG = 1.004G0.37
• B. 1.004G0.8
• C. hG = 0.0176G0.37
• D. 0.0176G1.37

Explanation: For air flowing perpendicular to the drying surface, the empirical correlation changes to hG = 1.004G^0.37.

• A. 25 cms
• B. 40% of the I.D. of the shell
• C. 5 cms
• D. I.D. of the shell

Explanation: Baffle spacing should not be reduced below about 5 cm, because closer spacing increases shell-side pressure drop and makes fabrication and…

• A. 0.3 to 0.8
• B. 8 to12
• C. 3.5 to 7.0
• D. 1.25 to 3.125

Explanation: Corrugated plates for conventional plate heat exchangers are commonly specified in the approximate 1.25 to 3.125 mm range in this…

• A. 0.5 to 1
• B. 1 to 1.5
• C. 1.5 to 2
• D. 2 to 2.5

Explanation: In a calandria evaporator, the downcomer or downtake cross-sectional area is typically about 0.5 to 1 times the total tube-flow area.

• A. 75% cut segmental baffle
• B. 25% cut segmental baffle
• C. Orifice baffle
• D. Disk and doughnut baffle

Explanation: The 25% cut segmental baffle is the usual industrial choice because it provides effective cross-flow over the tubes without imposing…

• A. Equal to
• B. Half
• C. One fourth
• D. Three fourth

Explanation: The ligament is the clear distance between adjacent tubes, and standard exchanger practice takes its minimum as about one-fourth of the…