Related Questions

The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are
A Re.Gz
B Nu, Pr
C Nu, Pr, Re
D Nu, Gz
A tank is filled by three pipes with uniform flow. The first two pipes operating simultaneously fill the tank in the same time during which the tank is filled by the third pipe alone. The second pipe fills the tank 5 hours faster than the first pipe and 4 hours slower than the third pipe. The time required by the first pipe is:
A 6 hours
B 10 hours
C 15 hours
D 30 hours
A water tank with 64-gallon capacity is filled by pipe A and emptied by pipe B. If the rate of water flow through pipe A is 2 gallons per hour, how many gallons per hour should flow through pipe B so that when both pipes are open, the initially empty tank shold be full in exactly 96 hours?
A 3/8
B 4/3
C 2/3
D 8/3
Water flows into an empty 64-gallon drum through pipe A and flows out through pipe B. If the rate of flow through A is 2 gallons/hour, how many gallons per hour must flow out through pipe B so that the drum is full in exactly 96 hours?
A 3/8
B 1/2
C 2/3
D 4/3
In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by
A Convection
B Radiation
C Conduction
D Both convection and conduction
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)
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
When a liquid is flowing through a pipe, the velocity of the liquid is
A Maximum at the centre and minimum near the walls
B Minimum at the centre and maximum near the walls
C Zero at the centre and maximum near the walls
D Maximum at the centre and zero near the walls
The velocity profile for a Bingham plastic fluid flowing (under laminar conditions) in a pipe is
A Parabolic
B Flat
C Flat near the wall and parabolic in the middle
D Parabolic near the wall and flat in the middle

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