Process Equipment and Plant Design

131. In a shell and tube heat exchanger having triangular pitch, the shell side equivalent diameter is given by

1. 4(0.86P² - πD₂/4)/πd
2. (P² - πD₂/4)/πd
3. 4(0.86P² - πD₂)/πd
4. (4P² + πD₂/4)/πd

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132. In a shell and tube heat exchanger, the 'tube pitch' is defined as the

1. O.D. of the tube for square pitch
2. Shortest distance between two adjacent tube holes
3. Shortest centre to centre distance between adjacent tubes
4. None of these

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133. In a shell and tube heat exchanger, the clearance of the tube is generally

1. Not less than one-fourth of the tube diameter or 3/16"
2. More than the tube diameter
3. Equal to the tube diameter
4. More in case of triangular pitch as compared to the square pitch tube layout

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134. In a shell and tube heat exchanger, the overall heat transfer co-efficient is proportional to the tube side (volumetric flow rate)0.8. This is valid, only when the ratio of the tube side film resistance to the total resistance is almost equal to

1. ∞
2. 1
3. 20.8
4. 2

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135. In a shell and tube heat exchanger, the shortest centre to centre distance between the adjacent tubes is

1. Called tube pitch
2. Called tube clearance
3. Always less than the diameter of the tube
4. None of these

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136. In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement

1. Results in higher shell side pressure drop
2. Can accomodate less number of tubes for a given shell diameter
3. Facilitates easier shell side cleaning; hence is more suitable for handling high dirt factor shell side fluid
4. Creates relatively lower turbulence on the shell side resulting in lower shell side heat transfer

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137. In a shell and tube heat exchanger, tube side _________ of the mass velocity.

1. Heat transfer co-efficient is proportional to 0.8th power
2. Pressure drop is proportional to the square
3. Both 'a' & 'b'
4. Neither 'a' nor 'b'

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138. In a thin cylindrical shell, the hoop stress is _________ stress.

1. Radial
2. Circumferential tensile
3. Compressive
4. Longitudinal

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139. In a vertical short tube evaporator (Calandria type), the

1. Tube dia of 2.5-7.5 cms, tube length of 75-200 cms and cylindrical drum dia of 1-6 metres are normally used
2. Area of central downtake is equal to 40 to 100% of total cross-sectional area of the surrounding tube
3. Liquor is inside the tube while the steam is outside the tube
4. All (A), (B) & (C)

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140. In actual operation of a bubble cap distillation tower, the _________ at the bottom of the tower is more than that at the top of the tower.

1. Molal flow rate of vapour
2. Vapour molecular weight
3. Pressure and temperature
4. All (A), (B) and (C)

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