Which of the following forced convection heat transfer equation
accounts for the liquid viscosity effect for viscous liquids?
(A) Dittus-Boelter equation
(B) Sieder-Tate equation
(C) Nusselt equation
(D) None of these
Description : The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re 0.8 , where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient ... pipe diameter (D) as (A) D-1.8 (B) D-0.2 (C) D0.2 (D) D1.8
Last Answer : (B) D-0.2
Description : Dittus-Boelter equation used for the determination of heat transfer coefficient is valid (A) For fluids in laminar flow (B) For fluids in turbulent flow (C) When Grashoff number is very important (D) For liquid metals
Last Answer : (B) For fluids in turbulent flow
Description : The Dittus-Boelter equation for convective heat transfer [(i.e. h = 0.023 (K/D) (Re) 0.8 (Pr) 0.4 ] cannot be used for (A) Low Reynold's number (B) Very low Grashoff number (C) Molten metals (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Dittus-Boelter equation cannot be used for molten metals mainly due to its very low (A) Prandtl number (B) Grashoff number (C) Thermal conductivity (D) Viscosity
Last Answer : (A) Prandtl number
Description : For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus-Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of (A) 1 (B) 1.74 (C) 6.1 (D) 37
Last Answer : (C) 6.1
Description : Nusselt number (for forced convection heat transfer) is a function of the __________ number. (A) Prandtl (B) Reynolds (C) Both (A) & (B) (D) Neither (A) nor (B)
Last Answer : (C) Both (A) & (B)
Description : Pick out the wrong statement. (A) In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2 (B) Sherwood number in mass transfer corresponds to ... tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side
Last Answer : (C) Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger
Description : Leidenfrost point is a term concerned with the (A) Condensation of the saturated vapor on a cold surface (B) Concentration of a corrosive solution by evaporation (C) Heat transfer between two highly viscous liquids (D) Boiling of a liquid on a hot surface
Last Answer : (D) Boiling of a liquid on a hot surface
Description : In forced convection, the Nusselt number is a function of (A) Re and Pr (B) Re and Gr (C) Pr and Gr (D) Re and Sc
Last Answer : (A) Re and Pr
Description : Nusselt number is a function of Prandtl number and __________ number of fluid in natural convection heat transfer. (A) Grashoff (B) Biot (C) Stanton
Last Answer : (A) Grashoff
Description : Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8 . Pr n , is not valid, if the value of (A) n = 0.4 is used for heating (B) n = 0.3 is used for cooling (C) Reynolds number for the flow involved is > 10000 (D) Reynolds number for the flow involved is < 2100
Last Answer : (D) Reynolds number for the flow involved is < 2100
Description : When warm and cold liquids are mixed, the heat transfer is mainly by (A) Conduction (B) Convection (C) Radiation (D) Both (A) & (C
Last Answer : (B) Convection
Description : Pick out the wrong statement. (A) A fluid mass is free from shearing forces, when it is made to rotate with a uniform velocit (B) Newton's law of viscosity is not applicable to the ... types of bearings (D) Rise of water in capillary tubes reduces with the increasing diameter of capillary tubes
Last Answer : (B) Newton's law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution
Description : The Fourier number (defined as a.t/L 2 ) is used in the analysis of problem involving heat transfer by (A) Forced convection (B) Natural convection (C) Transient conduction (D) Steady state conduction
Last Answer : (C) Transient conduction
Description : In which mode of heat transfer, the Biot number is important? (A) Transient heat conduction (B) Natural convection (C) Forced convection (D) Radiation
Last Answer : (A) Transient heat conduction
Description : Pick out the wrong statement. (A) In case of heat transfer by purely forced convection, GR /Re 2 ≤ 1 (B) The equivalent diameter of heat transfer for a duct of ... nucleate boiling depends basically on the ease with which the bubbles are formed and detached from the heating surface
Last Answer : (B) The equivalent diameter of heat transfer for a duct of square crosssection (having each side as 'x') is equal to 4x
Description : Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called (A) Radiation (B) Natural convection (C) Forced convection (D) Conduction
Last Answer : (C) Forced convection
Description : Mode of heat transfer involved in the cooling of air cooled internal combustion engine is (A) Conduction (B) Natural convection (C) Forced convection (D) None of these
Last Answer : (B) Natural convection
Description : In forced convection, the heat transfer depends on (A) Re, Pr (B) Re, Gr (C) Mainly Gr (D) Re only
Last Answer : (A) Re, Pr
Description : If heat transfer rate varies with the time, it is termed as (A) Forced convection (B) Steady state conduction (C) Monochromatic radiation (D) None of these
Last Answer : (D) None of these
Description : View factor is important in heat transfer by (A) Steady state conduction (B) Natural convection (C) Forced convection (D) Radiation
Last Answer : (D) Radiation
Description : When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is: (A) Free convection (B) Entry length problem in laminar forced ... (developing thermal boundary layer) (C) Mixed convection (both free and forced) (D) Forced convection
Last Answer : (C) Mixed convection (both free and forced)
Description : Heat transfer by __________ may not necessarily require the presence of a medium. (A) Conduction (B) Natural convection (C) Forced convection (D) Radiation
Description : Pick out the correct statement. (A) 1 kcal/hr.m.°C is equal to 1 BTU/hr. ft.°F (B) In steady state heat conduction, the only property of the substance which determines the ... in the direction of temperature rise (D) In heat transfer by forced convection, Grashoff number is very important
Last Answer : (B) In steady state heat conduction, the only property of the substance which determines the temperature distribution, is the thermal conductivity
Description : Forced recirculation of furnace gases is practised (A) To increase heat transfer by convection (B) To ensure uniform temperature (C) In furnaces, operating below 750°C (D) All (A), (B) and (C)
Description : In a furnace with heating element temperature at 1700°C, the dominant mechanism of heat transfer will be (A) Conduction (B) Radiation (C) Natural convection (D) Forced convection
Last Answer : (B) Radiation
Description : In pipe flow, heat is transferred from hot wall to the liquid by(A) Conduction only (B) Forced convection only (C) Forced convection and conduction (D) Free and forced convection
Last Answer : (C) Forced convection and conduction
Description : Explain with reason through which side of shell and tube heat exchanges, the following liquids are directed. (i) viscous liquid (ii) high pressure liquid (iii) corrosive liquid
Last Answer : Viscous liquid : Viscous liquid is passed through shell side Reason: because of the presence of baffles in the shell induce turbulence and hence increases heat transfer rate. High pressure liquid: High ... To avoid expensive alloy shells (in order to save the cost of expensive material for shell).
Description : Heat transfer by natural convection is enhanced in system with (A) High viscosity (B) High co-efficient of thermal expansio
Last Answer : (B) High co-efficient of thermal expansion
Description : Heat transfer occurs by natural convection because change in temperature causes difference in (A) Viscosity (B) Density (C) Thermal conductivity (D) Heat capacity
Last Answer : (B) Density
Description : Forced circulation evaporators are normally used for concentrating liquids having (A) Scaling characteristics (B) High viscosity (C) Both (A) & (B) (D) Neither (A) nor (B)
Description : Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when (A) Extracting solvent is cheaply & abundantly available ... very high (D) One of the liquid components has very high affinity towards the solvent
Last Answer : (D) One of the liquid components has very high affinity towards the solvent
Description : Which of the following is not applicable to liquid fuels? a) the viscosity of a liquid fuel is a measure of its internal resistance to flow. b) the viscosity of all liquid fuels decreases with ... the viscosity of liquid fuels, higher will be its heating value d) viscous fuels need heat tracing
Last Answer : c) higher the viscosity of liquid fuels, higher will be its heating value
Description : Nusselt number is related to Grashoff number (Gr) in turbulent & laminar flow respectively, in respect of free convection over a vertical flat plate as (A) Gr0.25, Gr (B) Gr0.25, Gr0.33 (C) Gr, Gr0.25 (D) Gr0.33, Gr0.25
Last Answer : Option A
Description : The Euler's equation for the motion of liquids is based upon the assumption that (A) The fluid is non - viscous, homogeneous and incompressible (B) The velocity of flow is uniform over the section (C) The flow is continuous, steady and along the stream line (D) All of the above
Last Answer : Answer: Option D
Description : Viscous & heat sensitive liquids are concentrated in __________ evaporators. (A) Open pan (B) Long tube (C) Agitated film (D) None of these
Last Answer : (C) Agitated film
Description : Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by (A) Eddies current (B) Conduction (C) Convection (D) None of these
Last Answer : (B) Conduction
Description : Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Sherwood (B) Schmidt (C) Peclet (D) Stanton
Last Answer : (A) Sherwood
Description : Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations. (A) Sherwood number in mass transfer is analogous to Nusselt number in heat transfer ... heat transfer (D) Reynolds number remains the same in both heat and mass transfer
Last Answer : (C) Reynolds number in mass transfer is analogous to Grashoff number in heat transfer
Description : jH factor for heat transfer is not a function of the __________ number. (A) Reynolds (B) Nusselt (C) Grashoff (D) Both (B) & (C)
Last Answer : (D) Both (B) & (C)
Description : Which of the following is concerned with both heat and mass transfer? (A) Lewis relationship (B) Nusselt number (C) Kutateladze number (D) Froude number
Last Answer : (A) Lewis relationship
Description : The rate of heat transfer is a product of overall heat transfer coefficient, the difference in temperature and the (A) Heating volume (B) Heat transfer area (C) Nusselt number (D) None of these
Last Answer : (B) Heat transfer area
Description : Value of Nusselt number [Nu = (hD/k)] for the heat transfer byconduction from a droplet or a spherical particle to a surrounding stagnant film is (A) 0.5 (B) 2 (C) 10 (D) 100
Last Answer : (B) 2
Description : jH factor for heat transfer depends upon the __________ number. (A) Biot (B) Nusselt (C) Reynolds (D) Prandtl
Last Answer : (C) Reynolds
Description : The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is (A) Nusselt number (B) Sherwood number (C) Schmidt number (D) Stanton numbe
Last Answer : (C) Schmidt number
Description : Nusselt number/Biot number varies (A) Inversely with thermal conductivity (B) Directly with heat transfer co-efficient (C) Directly with thermal conductivity (D) Inversely with the dimension of the solid
Last Answer : (A) Inversely with thermal conductivity
Description : The non-dimensional temperature gradient in a liquid at the wall of a pipe is the (A) Heat flux (B) Nusselt number (C) Prandtl number (D) Schmidt number
Last Answer : (A) Heat flux
Description : The ratio of kinematic viscosity to thermal diffusivity is called the __________ number. (A) Peclet (B) Prandtl (C) Stanton (D) Nusselt
Last Answer : (B) Prandtl
Description : Vacuum filter is most suitable for the (A) Removal of fines from liquid (B) Liquids having high vapour pressure (C) Liquids of very high viscosity (D) None of these
Description : During agitation of liquids, power consumption during laminar flow is not proportional to the (A) Density of the liquid (B) Viscosity of the liquid (C) Cube of impeller diameters (D) Square of rotational speed
Last Answer : (A) Density of the liquid