Description : Prandtl number for most of dry gases is about (A) 0.001 (B) 0.72 (C) 70 (D) 150
Last Answer : (B) 0.72
Description : A mixture of 10% C6H6 vapour in air at 25°C and 750 mm Hg has a dew point of 20°C. Its dew point at 30°C and 700 mm Hg will be around __________ °C. (A) 21.7 (B) 20 (C) 27.3 (D) 18.7
Last Answer : (D) 18.7
Description : A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The ... = 283 s (B) t = 356 s (C) t = 400 s (D) t = 800 s
Last Answer : (D) t = 800 s
Description : Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3 /min) of density 800 kg/m3 and specific heat of ... mean temperature difference in °C is approximately (A) 32 (B) 37 (C) 45 (D) 50
Last Answer : (A) 32
Description : A batch adiabatic reactor at an initial temperature of 373°K is being used for the reaction, A → B. Assume the heat of reaction is - 1kJ/mole at 373°K and heat capacity of both A and B to be constant and equal ... rise after a conversion of 0.5 will be: (A) 5°C (B) 10°C (C) 20°C (D) 100°C
Last Answer : (B) 10°C
Description : Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is (A) 0.1 (B) > 1 (C) < 1 (D) 1
Last Answer : (A) 0.1
Description : Prandtl and Reynold's analogies are identical for Prandtl number value of (A) 0 (B) 0.5 (C) 1 (D) 5
Last Answer : (C) 1
Description : Prandtl and Reynolds analogy are same, when Prandtl number is (A) 0.5 (B) 1 (C) > 2 (D) 1.5
Last Answer : (B) 1
Description : Colburn analogy is applicable for the value of Prandtl number from (A) 0.001 to 1 (B) 0.6 to 120 (C) 0.5 to 5 (D) 120 to 400
Last Answer : (B) 0.6 to 120
Description : . For what value of Prandtl number, the Col-burn analogy is (A) 0.06 to 120 (B) 0.6 to 120 (C) 1 to 103 (D) 1 to 50
Description : Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is (A) 0.2 (B) 0.4 (C) 0.6 (D) 0.8
Last Answer : (C) 0.6
Description : At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe? (A) 0.5 (B) < 0.5 (C) > 0.6 (D) < 0.1
Last Answer : (C) > 0.6
Description : Value of Prandtl number for water ranges from (A) 1 to 2 (B) 5 to 10 (C) 100 to 500 (D) 1000 to 2000
Last Answer : (B) 5 to 10
Description : Which has the lowest Prandtl number? (A) Liquid metal (B) Aqueous solution (C) Water (D) Lube oi
Last Answer : (A) Liquid metal
Description : Which of the following has the lowest Prandtl number? (A) Molten sodium (a coolant used in fast breeder reactor) (B) Water (C) Transformer oil (D) Dilute H2SO4
Last Answer : (A) Molten sodium (a coolant used in fast breeder reactor)
Description : 3.0 ml of raw sewage is diluted to 300 ml. The D.O. concentration of the diluted sample at the beginning of the test was 8 mg/l. After 5 dayincubation at 20°C, the D.O. concentration was 5 mg/l. The BOD of raw sewerage is A. 100 mg/l B. 200 mg/l C. 300 mg/l D. 400 mg/l
Last Answer : ANS: C
Description : Onion seeds can germinate at a temperature of : a. 0-1°C b. 1-5°C c. 5-11°C d. 15-20°C
Last Answer : 1-5°C
Description : Temperature and gage pressure maintained during the manufacture of cold SBR (styrene butadiene rubber) are (A) 5°C and 1 kgf/cm2 (B) - 20°C and 1 kgf/cm2 (C) 0°C and 1 kgf/cm2 (D) 0°C and 3 kgf/cm
Last Answer : (A) 5°C and 1 kgf/cm
Description : Extractor temperature is maintained at -20°C in Edeleanu process to reduce the __________ of kerosene. (A) Smoke point (B) Paraffins (C) Aromatics (D) Naphthenes
Last Answer : (B) Paraffins
Description : Normal temperature and pressure (N.T.P.) corresponds to (A) 0°C and 760 mm Hg (B) 15°C and 760 mm Hg (C) 20°C and 760 mm Hg (D) 0°C and 1 kgf/cm2
Last Answer : (C) 20°C and 760 mm Hg
Description : Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Schmidt (B) Sherwood (C) Peclet (D) Stanton
Last Answer : (A) Schmidt
Description : Which of the following plays an important role in problems of simultaneous heat and mass transfer (A) Lewis number (B) Schmidt number (C) Prandtl number (D) Sherwood number
Last Answer : (A) Lewis number
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 : 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 : Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is (A) 1 (B) < 1 (C) > 1 (D) > 5
Last Answer : (B) < 1
Description : Prandtl number is the ratio of (A) Mass diffusivity to thermal diffusivity (B) Momentum diffusivity to thermal diffusivity (C) Thermal diffusivity to mass diffusivity (D) Thermal diffusivity to momentum diffusivity
Last Answer : (B) Momentum diffusivity to thermal diffusivity
Description : At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical? (A) 1 (B) < 1 (C) > 1 (D) None of these
Last Answer : (A) 1
Description : Which of the following is unimportant in forced convection? (A) Reynolds number (B) Prandtl number (C) Grashoff number (D) None of these
Last Answer : (C) Grashoff number
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 : . If Prandtl number is greater than the Schmidt number, then the (A) Thermal boundary layer lies inside the concentration boundary layer (B) Concentration boundary layer lies inside the thermal boundary ... (D) Hydrodynamic (i.e., momentum) boundary layer is thicker than the other two
Last Answer : (A) Thermal boundary layer lies inside the concentration boundary layer
Description : The ratio of momentum diffusivity to thermal diffusivity is the __________ number. (A) Prandtl (B) Nusselt (C) Stanton (D) Grashoff
Last Answer : (A) Prandtl
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 : Natural convection is characterised by (A) Grashoff number (B) Peclet number (C) Reynolds number (D) Prandtl number
Last Answer : (A) Grashoff number
Description : Prandtl number is the ratio of (A) Momentum diffusivity to mass diffusivity (B) Momentum diffusivity to thermal diffusivity (C) Thermal diffusivity to mass diffusivity (D) Thermal diffusivity to momentum diffusivity
Description : Prandtl number is given by (A) CP µ/a (B) hD/k (C) CP µ/k (D) µ/h CP
Last Answer : (C) CP µ/k
Description : For __________ Prandtl number values, the heat conduction will be negligible in the buffer zone. (A) Extremely low (B) Low (C) High (D) No
Last Answer : (C) High
Description : jH factor for heat transfer depends upon the __________ number. (A) Biot (B) Nusselt (C) Reynolds (D) Prandtl
Last Answer : (C) Reynolds
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 : 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 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 : Cpµ/K is termed as the __________ number. (A) Grashoff (B) Nusselt (C) Prandtl (D) Stanton
Last Answer : (C) Prandtl
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 : 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) (A) NPr (B) NPr 1/3 (C) NPr -1 (D) NPr -1/3
Last Answer : (B) NPr 1/3
Description : For what value of Prandtl number, St = f/2? (A) 1.5 (B) 1 (C) > 1 (D) < 1
Description : Prandtl number is the reciprocal of (A) Thermal diffusivity/Momentum diffusivity (B) Thermal diffusivity × Momentum (C) Thermal diffusivity × Mass diffusivity (D) Mass diffusivity × Momentum diffusivity
Last Answer : (A) Thermal diffusivity/Momentum diffusivity
Description : Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer. (A) Grashoff (B) Reynolds (C) Both 'a' & 'b' (D) Prandtl & Grashoff
Last Answer : (D) Prandtl & Grashoff
Description : Cp /Cv is termed as (A) Adiabatic constant (B) Mach number (C) Weber number (D) Prandtl number
Last Answer : (A) Adiabatic constan
Description : The hydrodynamic and thermal boundary layers will merge, when (A) Prandtl number is one (B) Schmidt number tends to infinity (C) Nusselt number tends to infinity (D) Archimedes number is greater than 10000
Last Answer : (A) Prandtl number is one
Description : Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of (A) Grashoff number (B) Grashoff number & Reynolds number (C) Reynolds number (D) Grashoff number & Prandtl number
Last Answer : Option D
Description : Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low ... Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers
Last Answer : (A) Mechanical agitation is required, if the system has low interfacial tension