Related Questions

In a double pipe (concentric) heat exchanger, the hydraulic radius for heat transfer (for a fluid flowing through the annulus) would be
A Same as that for fluid flow
B Less than that for fluid flow
C More than that for fluid flow
D D2 - D1 (D1 and D2 are I.D. of inner and outer pipes respectively)
Read the following passage carefully and then choose the right word to complete the sentence that follows. Rockets are very expensive as it can be used only once. Appled scientists have therefore develped a reusable space craft called a space shuttle which takes off like a rocket; however, does no get destroyed as it returns to earth. It can also be used to lunch satellired into space, retrieve them from space if any repairing os required and allow around 8 scientists to crryout experiments in space. The space shuttle does not get.
A flattened
B enlarged
C ruined
D developed
Two fluids are flowing through two similar pipes of the same diameter. The Reynold's number is same. For the same flow rate if the viscosity of a fluid is reduced to half the value of the first fluid, the pressure drop will
A Increase
B Decrease
C Remain unchanged
D Data insufficient to predict relative pressure drop
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
Pressure drop (Δp) for a fluid flowing in turbulent flow through a pipe is a function of velocity (V) as
A V1.8
B V-0.2
C V2.7
D V2
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 $$\frac{{{{\text{d}}_1} + {{\text{d}}_2}}}{{{{\text{d}}_2}}}$$
In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid
A Varies directly as the area and the LMTD
B Directly proportional to LMTD and inversely proportional to the area
C Varies as square of the area
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

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