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The value of Prandtl number for air is about _______________________?
Related MCQs
Total emissivity of polished silver compared to black body is__________?
The value of the wavelength for maximum emissive power is given by __________?
The unit of overall coefficient of heat transfer is__________?
All radiations in a black body are__________?
According to Kirchoff’s law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a __________?
Joule sec is the unit of__________?
The concept of overall coefficient of heat transfer is used in case of heat transfer by__________?
In counter flow heat exchangers__________?
Fourier’s law of heat conduction is valid for__________?
LMTD in case of counter flow heat exchanger as compared-to parallel flow heat exchanger is __________?
According of Kirchhoff’s law__________?
A steam pipe is to be insulated by two insulating materials put over each other . For best results__________?
In heat exchangers, degree of approach is defined as the difference between temperatures of__________?
A non-dimensional number generally associated with natural convection heat transfer is__________?
Emissivity of a white polished body in comparison to a black body is__________?
Two balls of same material and finish have their diameters in the ratio of 2 : 1 and both are heated to same temperature and allowed to cool by radiation. Rate of cooling by big ball as compared to smaller one will be in the ratio of__________?
Heat conducted througfi unit area and unit thick face per unit time when temperature difference between opposite faces is unity,is called__________?
A grey body is one whose absorptivity__________?
The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as __________?
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__________?
Unit of thermal diffusivity is__________?
Film coefficient is defined as Inside diameter of tube__________?
Thermal conductivity of wood depends on__________?
Thermal diffusivity is __________?
Moisture would find its way into insulation by vapour pressure unless it is prevented by __________ ?
Heat transfer by radiation mainly depends upon__________?
Which of the following has maximum value of thermal conductivity__________?
The amount of heat flow through a body by conduction is__________?
Heat flows from one body to other when they have__________?
Which of the following has least value of conductivity__________?
Thermal conductivity of glass-wool varies from sample to sample because of variation in __________ ?
According to Prevost theory of heat exchange __________?
Thermal diffusivity of a substance is __________?
The ratio of heat flow Q1/Q2 from two walls of same thickness having their thermal conductivities as ATj – 2K2 will be __________?
Heat is transferred by all three modes of transfer, viz, conduction, convection and radiation in __________?
Thermal conductivity of a material may be defined as the__________?
Which of the following is expected to have highest thermal conductivity__________?
In heat transfer, conductance equals conductivity (kcal/hr/sqm/°C/cm) divided by __________?
The time constant of a thermocouple is__________?
Thermal conductivity of water at 20°C is of the order of__________?
Total heat is the heat required to__________?
Thermal conductivity of air with rise in temperature__________?
Thermal conductivity of air at room temperature in kcal/m hr °C is of the order of__________?
Cork is a good insulator because it has__________?
Metals are good conductors of heat because__________?
Temperature of steam at around 540°C can be measured by __________?
Thermal conductivity of water in general with rise in temperature __________?
Which of the following is a case of steady state heat transfer __________?
Which of the following is the case of heat transfer by radiation __________?
Heat flowing from one side to other depends directly on __________?
Heat transfer in liquid and gases takes place by__________?
The value of Prandtl number for air is about _______________________?
A. 0.1
B. 0.3
C. 0.7
D. 1.7
E. 10.5
Correct Answer:
0.7
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Last Updated:
January 24, 2019