Related Questions

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
A $$\frac{{{{\text{d}}_1}}}{{{{\text{d}}_1} + {{\text{d}}_2}}}$$
B $$\frac{{{{\text{d}}_2}}}{{{{\text{d}}_1} + {{\text{d}}_2}}}$$
C $$\frac{{{{\text{d}}_1} + {{\text{d}}_2}}}{{{{\text{d}}_1}}}$$
D $$\frac{{{{\text{d}}_1} + {{\text{d}}_2}}}{{{{\text{d}}_2}}}$$
The scales form in heat exchanges after a period of operation and provide additional resistance to heat transfer with some heat transfer coefficient . The reciprocal of this scale heat transfer coefficient is called .
A scaling factor
B forming factor
C resisting factor
D fouling factor
Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the
A Surrounding temperature
B Average temperature of the fin
C Temperature of the fin end
D Constant temperature equal to that of the base
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
A Are easier to clean
B Are less prone to fouling
C Can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less
D None of these
The ratio of the useful heat drop to the isentropic heat drop is called
A Condenser efficiency
B Nozzle efficiency
C Boiler efficiency
D Vacuum efficiency
Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because
A Convection becomes important
B Conduction becomes important
C Radiation becomes important
D Sub-cooled boiling occurs
The ratio of total useful heat drop to the total isentropic heat drop, is called
A Stage efficiency
B Internal efficiency
C Rankine efficiency
D None of these
Applying a pressure drop across a capillary results in a volumetric flow rate 'Q' under laminar flow conditions. The flow rate for the same pressure drop, in a capillary of the same length but half the radius is
A $$\frac{{\text{Q}}}{2}$$
B $$\frac{{\text{Q}}}{4}$$
C $$\frac{{\text{Q}}}{8}$$
D $$\frac{{\text{Q}}}{{16}}$$
The equivalent diameter for fluid flow through square cross section channel of side 'x', for pressure drop calculation purpose is given by
A 4x
B 2x
C x
D $$\sqrt {\text{x}} $$
For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus-Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of
A 1
B 1.74
C 6.1
D 37

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