In forced convection, the heat transfer depends on _______________?
In forced convection, the heat transfer depends on _______________?
A. Re, Pr
B. Re, Gr
C. Mainly Gr
D. Re only
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The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by ______________ times, when the number of tube passes is increased to 8?
The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by ______________ times, when the number of tube passes is increased to 8?A. 20.8
B. 40.8
C. 40.4
D. 20.4Absorptivity and reflectivity of a perfect black body are respectively _______________?
Absorptivity and reflectivity of a perfect black body are respectively _______________?A. 1 and 0
B. 0 and 1
C. 1 and ∞
D. 0 and 0.5Baffle spacing ____________________?
Baffle spacing ____________________?A. Is not the same as baffle pitch
B. Should be less than one fifth the diameter of the shell
C. Should be less than the inside diameter of the shell
D. None of theseThe inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C- 1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m-2.°C-1. The rate of heat loss from the outer surface in W.m-2is__________________?
The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C- 1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m-2.°C-1. The rate of heat loss from the outer surface in W.m-2is__________________?A. 165.4
B. 167.5
C. 172.5
D. 175When vaporisation takes place directly at the heating surface, it is called________________?
When vaporisation takes place directly at the heating surface, it is called________________?A. Film boiling
B. Nucleate boiling
C. Vapour binding
D. None of theseWater is normally used as a coolant in the heat exchange equipments mainly because of its___________________?
Water is normally used as a coolant in the heat exchange equipments mainly because of its___________________?A. Abundance & high heat capacity
B. Low density
C. Low viscosity
D. High fluidity