20601. A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be
20602. Which area is used in case of heat flow by conduction through a cylinder ?
20603. Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer can not take place
20604. The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is
20605. Finned tube heat exchangers
20606. The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation.
20607. Which one gives the monochromatic emissive power for black body radiation ?
20608. For what value of Prandtl number, St = f/2?
20609. In a shell and tube heat exchanger,
20610. Dietus-Boelter equation used for the determination of heat transfer co-efficient is valid
20611. The equation, , corrosponds to __________ analogy.
20612. For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it
20613. Out of the following four assumptions used in the derivation of the equation for LMTD , which one is subject to the largest deviation in practice ?
20614. Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because
20615. Resistance to heat flow by conduction is proportional to (where, t & ρ are thickness & density of the material respectively and A = area normal to the direction of heat flow. )
20616. Temperature profile in steady state heat transfer is
20617. For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it
20618. When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as __________ boiling.
20619. Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter)
20620. Stefan-Boltzman law which describes the radiation heat transfer states that, it is proportional to (where, t = temperature in °C T = absolute temperature in ° K )
20621. The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is
20622. What is the unit of thermal conductivity ?
20623. The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of 'n' is exactly 4 for
20624. It is not preferable to use superheated steam in evaporators, because of its very
20625. It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is
20626. LMTD for counterflow and prallel flow heat exchanger will be the same, when the
20627. For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number)
20628. The range of electromagnetic spectrum important in heat transfer by radiation is __________ microns.
20629. Use of transverse baffles in a shell and tube heat exchanger is done to increase the
20630. The actual temperature drop across the heating surface of an evaporator depends on the
20631. Economy of a multiple effect evaporator depends upon the
20632. The Graetz number is concerned with the
20633. Solid angle subtended by the finite surface at the radiating element is
20634. Which river is known as Nile of Kerala?
20635. In forced convection, the heat transfer depends on
20636. With increase in temperature, the thermal conductivity of most liquids
20637. Heat transfer by __________ may not necessarily require the presence of a medium.
20638. Who established Atmavidya Sangham?
20639. In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used
20640. Stefan-Boltzman law applies to __________ body.
20641. The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is
20642. A perfect black body is a perfect __________ of radiation.
20643. In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid.
20644. The non-dimensional temperature gradient in a liquid at the wall of a pipe is the
20645. An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a
20646. Which of the following is directly concerned with the heat transfer ?
20647. Who won the MV Pylee Award 2016?
20648. Planck's distribution law is valid for __________ bodies.
20649. For hot feed, forward feeding as compared to backward feeding results in __________ economy.
20650. Radiation energy is emitted by all the substances, which are above