Process Equipment and Plant Design

121. In a double pipe (concentric) heat exchanger, the hydraulic radius for heat transfer (for a fluid flowing through the annulus) would be

1. Same as that for fluid flow
2. Less than that for fluid flow
3. More than that for fluid flow
4. D₂ - d₁ (d₁ and D₂ are I.D. of inner and outer pipes respectively)

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122. In a double pipe concentric heat exchanger, the equivalent diameter of annulus for heat transfer would be (where, d₁ and D₂ are I.D. of inner and outer pipes)

1. (D₂² - D₁²)/D₁²
2. D₂ - D₁
3. (D₂² - D₁²)/D₂²
4. None of these

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123. In a heat exchanger, shell side fluid velocity can be changed by changing the tube

1. Layout
2. Pitch
3. Both (A) & (B)
4. Neither (A) nor (B)

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124. In a multipass shell and tube heat exchanger, the baffles on shell side is primarily provided for

1. Reducing scale deposition
2. Increasing pressure drop
3. Fixing the tubes
4. Creating turbulence

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125. In a multipass shell and tube heat exchanger, the shell side cross flow area does not depend upon

1. Baffle spacing
2. Clearance
3. Pitch
4. None of these

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126. In a multiple effect evaporator system having 'n' effects, the amount of water evaporated per unit surface area in approximately equal to _________ times that in a single effect.

1. nth
2. (1/n)th
3. 0.5 nth
4. 1.5 nth

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127. In a pressure vessel containing multiple openings of various dimensions at different parts, stress concentration at the edges of the opening is maximum which becomes negligibly small beyond the area covered by _________ times the hole diameter.

1. Two
2. Five
3. Ten
4. Twenty

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128. In a rotary drier, the average retention time of solid is (where Z = length of the drier, metres ρ = apparent solid density, kg/m3 L = flow rate of dry solids, kg/see. m² drier crosssection H = hold up of solid.)

1. Z.H.ρ/L
2. L/Z.H.ρ
3. H.ρ/L
4. Z.H/ρL

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129. In a shell and tube heat exchanger for a given heat transfer surface area, smaller diameter tubes are favoured as compared to larger diameter ones; because the smaller diameter tubes

1. Are easier to clean
2. Are less prone to fouling
3. Can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less
4. None of these

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130. In a shell and tube heat exchanger having square pitch, the shell side equivalent diameter is given by (where, P = pitch, d = outside diameter of the tube)

1. 4(P² - π#960;d²/4)/πd
2. (P² - rd²/4)/rd
3. 4P²/πd
4. πd/4P²

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