101. Diameter of rivet hole (d, mm) and the plate thickness (t, mm) are related by Unwin's formula as

102. What is the minimum recommended ligament for square pitch arrangement in case of heat exchangers?

103. Theoretically calculated diameter of the stripping section of the continuous rectification column is __________ that of the enriching section.

104. In a double pipe concentric heat exchanger, the equivalent diameter of annulus for heat transfer would be (where, D

_{1}and D_{2}are I.D. of inner and outer pipes)105. For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is

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