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.Management Sciences
Category: Heat Transfer
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
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
E. none of the above
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