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.Management Sciences
Category: Heat Transfer
In free con-vection heat transfer, Nusselt number is function of________________?
A. Grashoff no. and Reynold no
B. Grashoff no and Prandtl no.
C. Prandtl no. and Reynold no
D. Grashoff no., Prandtl no and Reynold no
E. none of the above
Thermal conductivity of air with rise in temperature__________________?
A. increases
B. decreases
C. remains constant
D. may increase or decrease depending on temperature
E. none of the above
Joule sec is the unit of_________________?
A. universal gas constant
B. kinematic viscosity
C. thermal conductivity
D. Planck’s constant
E. none of the above
According to Stefan’s law, the total radiation from a black body per second per unit area is proportional to____________________?
A. absolute temperature
B. T2
C. T5
D. t
E. l/T
The emissive power of a body depends upon its___________________?
A. temperature
B. wave length
C. physical nature
D. all of the above
E. none of the above
Thermal conductivity of air at room temperature in kcal/m hr °C is of the order of__________________?
A. 0.002
B. 0.02
C. 0.01
D. 0.1
E. 0.5
A non-dimensional number generally associated with natural convection heat transfer is________________?
A. Grashoff number
B. Nusselt number
C. Weber number
D. Prandtl number
E. Reynold number
Log mean temperature difference in case of counter flow compared to parallel flow will be________________?
A. same
B. more
C. less
D. depends on other factors
E. none of the above
All radiations in a black body are___________________?
A. reflected
B. refracted
C. transmitted
D. absorbed
E. partly reflected and partly absorbed
Film coefficient is defined as Inside diameter of tube________________?
A. Equivalent thickness of film
B. Thermal conductivity Equivalent thickness of film Specific heat x Viscocity
C. Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity
D. Film coefficient x Inside diameter Thermalconductivity
E. none of the above
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