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Post a comment. Latest Heat Transfer Questions and Answers pdf free download 1. Unit of thermal conductivity in M. Ans: b 2. Unit of thermal conductivity in S. Ans: e 3. Ans: b 4. Ans: b 5. Ans: c 6.
Ans: a 7. Ans: c 8. Sensible heat is the heat required to a change vapour into liquid b change liquid into vapour c increase the temperature of a liquid of vapour d convert water into steam and superheat it e convert saturated steam into dry steam.
Ans: c 9. Ans: b Which of the following is the case of heat transfer by radiation a blast furnace b heating of building c cooling of parts in furnace d heat received by a person from fireplace e all of the above.
Ans: d Ans: c Pick up the wrong case. Heat flowing from one side to other depends directly on a face area b time c thickness d temperature difference e thermal conductivity. Metals are good conductors of heat because a their atoms collide frequently b their atoms-are relatively far apart c they contain free electrons d they have high density e all of the above.
Ans: a Which of the following is a case of steady state heat transfer a I. Ans: e Total heat is the heat required to a change vapour into liquid b change liquid into vapour c increase the temperature of a liquid or vapour d convert water into steam and superheat it e convert saturated steam into dry steam.
Thermal conductivity of water in general with rise in temperature a increases b decreases c remains constant d may increase or decrease depending on temperature e none of the above. Heat flows from one body to other when they have a different heat contents b different specific heat c different atomic structure d different temperatures e none of the above.
The amount of heat flow through a body by conduction is a directly proportional to the surface area of the body b directly proportional to the temperature difference on the two faces of the body c dependent upon the material of the body d inversely proportional to the thickness of the body e all of the above. Which of the following has least value of conductivity a glass b water c plastic d rubber e air. According to Prevost theory of heat exchange a it is impossible to transfer heat from low temperature source to t high temperature source b heat transfer by radiation requires no medium c all bodies above absolute zero emit radiation d heat transfer in most of the cases takes place by combination of conduction, convection and radiation e rate of heat transfer depends on thermal conductivity and temperature difference.
Heat transfer by radiation mainly depends upon a its temperature b nature of the body c kind and extent of its surface d all of the above e none of the above. Thermal diffusivity is a a dimensionless parameter b function of temperature c used as mathematical model d a physical property of the material e useful in case of heat transfer by radiation.
Thermal diffusivity of a substance is. 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. 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.
Heat conducted througfi unit area and unit thick face per unit time when temperature difference between opposite faces is unity,is called a thermal resistance b thermal coefficient c temperature gradient d thermal conductivity e heat-transfer. 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. 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.
In heat exchangers, degree of approach is defined as the difference between temperatures of a cold water inlet and outlet b hot medium inlet and outlet c hot medium outlet and cold water inlet d hot medium outlet and cold water outlet e none of the above. A steam pipe is to be insulated by two insulating materials put over each other.
Fourier's law of heat conduction is valid for a one dimensional cases only b two dimensional cases only c three dimensional cases only d regular surfaces having non-uniform temperature gradients e irregular surfaces. According of Kirchhoff's law, a radiant heat is proportional to fourth power of absolute temperature b emissive power depends on temperature c emissive power and absorptivity are constant for all bodies d ratio of emissive power to absorptive power is maximum for perfectly black body e ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body.
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. The value of Prandtl number for air is about a 0.
The value of the wavelength for maximum emissive power is given by — a Wien's law b Planck's law c Stefan's law d Fourier's law e Kirchhoff's law. The energy distribution of an ideal reflector at higher temperatures is largely in the range of a shorter wavelength b longer wavelength c remains same at all wavelengths d wavelength has nothing to do with it e none of the above. Total emissivity of polished silver compared to black body is a same b higher c more or less same d very much lower e very much higher.
According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to a absolute temperature b square of temperature c fourth power of absolute temperature d fourth power of temperature e cube of absolute temperature. Which of the following property of air does not increase with rise in temperature a thermal conductivity b thermal diffusivity c density d dynamic viscosity e kuiematic viscosity.
In free con-vection heat transfer, Nusselt number is function of a Grashoff no. The thermal diffusivities for gases are generally a more than those for liquids b less than those for liquids c more than those for solids d dependent on the viscosity e same as for the liquids.
The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. The total emissivity power is. If the transmissivity of the body be 0. The amount of radiation mainly depends on a nature of body b temperature of body c type of surface of body d all of the above e none of the above.
Absorptivity of a body will be equal to its emissivity a at all temperatures b at one particular temperature c when system is under thermal equi-librium d at critical temperature e for a polished body.
A perfect black body is one which a is black in colour b reflects all heat c transmits all heat radiations d abslprbs heat radiations of all wave lengths falling on it e fully opaque. Planck's law holds good for a black bodies b polished bodies c all coloured bodies d all of the above e none of the above. Ans: d. Posted by engineering raju Email This BlogThis! Newer Post Older Post Home. Subscribe to: Post Comments Atom.
Heat conduction is a mechanism of heat transfer from a region of high temperature to a region of low temperature within a medium [solid, liquid or gases] or different medium in direct physical contact. State Fouriers law of conduction. The rate of heat conduction is proportional to the area measured normal to the direction of heat flow and to the temperature gradient in that direction. Define Thermal conductivity. Thermal conductivity is defined as the ability of a substance to conduct heat. Write down the equation for conduction of heat through a slab or plane wall. Write down the equation for conduction of heat through a hollow cylinder.
One should spend 1 hour daily for months to learn and assimilate Heat Transfer comprehensively. Navigate to your page and exercise. Read the instructions on the answer sheets. In other heat exchangers, heat transfer between fluids takes place through a separating wall or into and out of a wall in a transient manner. A physical property of a substance that characterises the ability of the substance to transfer heat. Electrostatic printing is all done with machines. Heat transfer co-efficient for the cooling water, whether on shell side or tube side is the same.
Diffusion heat transfer is due to random molecular motion. Neighboring molecules move randomly and transfer energy between one another - however there is no bulk motion. Radiation heat transfer, on the other hand, is the transport of heat energy by electromagnetic waves. All bodies emit thermal radiation. In particular, notice that unlike diffusion, radiation heat transfer does not require a medium and is thus the only mode of heat transfer in space.
Heat Transfer Viva Questions - Free download as Word Doc .doc /.docx), PDF File .pdf), Text File .txt) or read online for free. Heat Transfer.
Define heat transfer? Heat transfer can be defined as the transmission of energy from one region to another due to temperature difference. What is conduction? Heat conduction is a mechanism of heat transfer from a region of high temperature to a region of low temperature within a medium [solid, liquid or gases] or different medium in direct physical contact. The rate of heat conduction is proportional to the area measured normal to the direction of heat flow and to the temperature gradient in that direction.
Heat conduction is a mechanism of heat transfer from a region of high temperature to a region of low temperature within a medium [solid, liquid or gases] or different medium in direct physical contact. State Fouriers law of conduction. The rate of heat conduction is proportional to the area measured normal to the direction of heat flow and to the temperature gradient in that direction. Define Thermal conductivity.
Heat transfer rate per unit area by conduction is proportional to the normal temperature gradient. A physical property of a substance that characterises the ability of the substance to transfer heat. The ratio of product of thermal conductivity and area and the wall thickness. Walls of several heterogeneous layers. Mean rndius for heat transfer by conduction through hollow cylinder of radii r1 and r2.
Post a comment. Latest Heat Transfer Questions and Answers pdf free download 1. Unit of thermal conductivity in M. Ans: b 2. Unit of thermal conductivity in S. Ans: e 3.
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Define Heat Transfer. Heat transfer can be defined as transmission of energy from one region to another region due to temperature difference. What are the modes of heat transfer?
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