A. The condensing film co-efficient is about 3 times lower for vertical condenser as compared to the equivalent horizontal condenser for identical situation
B. Film co-efficient for vaporisation decreases as a result of vapor binding
C. In industrial practice, sub-cooling of condensate is required, when the condensate is a volatile
liquid and is to be transferred for storage
D. Overall heat transfer co-efficient in a heat exchanger is controlled by the value of the film coefficient,
which is higher
Related Mcqs:
- Pick out the wrong statement ?
A. Heat transfer from a hot body to cold body by the emission of heat waves is called radiation
B. Filmwise condensation takes place on non-wettable surfaces
C. The boiling point of a solution is affected by liquid head as well as boiling point elevation
D. None of these - 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 Nusselt number in heat transfer and Schmidt number to Prandtl number
C. Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger
D. Hot gases at moderate pressure are usually in the shell side of shell and tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side - Pick out the wrong statement/
A. The emissivity of a surface decreases, if it gets corroded by atmospheric environment
B. The emissivity of a surface increases with increase in surface roughness
C. The emissivity of a polished surface is quite low
D. The emissivity of a non-metallic surface decreases with increase in the temperature - Pick out the wrong statement?
A. In process heat exchangers, saturated steam is preferred over the superheated steam
B. The maximum is the emissive power of a surface at a temperature T1 occurs at a wavelength
of λ1. If the surface temperature is halved, the maximum in the emissive power would occur at
a wavelength of 0.5 λ1
C. When a vertical plate is heated in infinite air environmental under natural convection
conditions, the velocity profile in air, normal to the plate, exhibits a maximum
D. A body at 925 K emits an energy of 1.42 x 1011ζW/m2 (ζ is the Stefan-Boltzmann constant) in
the wavelength band between 3 μm to 4 μm. The fraction of this energy in the total energy
emitted over the entire wavelength range is equal to emissivity - Pick out the wrong statement ?
A. With change in temperature, the radiant energy emitted by a black body remains unchanged
B. Absorptivity of a body approaches unity in case of diffuse reflection
C. Absorptivity of a perfectly black body is unity
D. Value of Stefan-Boltzmann constant is 4.876 × 10-8 KCal/m2.hr.°K4 - Pick out the wrong statement?
A. Reciprocal of the resistance to heat flow is called thermal conductance
B. Unit of thermal conductance is W/°K
C. Thermal conductance of a wall of thickness ‘L’, thermal conductivity ‘k’ and heat flow area ‘A’ is kL/A
D. None of these - Pick out the wrong statement?
A. Swenson-Walker crystalliser is a batch crystalliser
B. Super saturation of the solution is the driving potential for a crystal growth
C. The liquor left after the removal of crystals from a solution is called mother liquor
D. The first stage of crystal formation is called nucleation - Pick out the wrong statement ?
A. Heat transfer by radiation cannot occur across an absolute volume
B. In case of a shell and tube heat exchanger, the pressure drop through the shell is proportional to the number of times the fluid crosses the bundle between baffles
C. Propagation velocity for travel of heat radiation through vacuum is equal to the velocity of the light
D. The amount of heat involved in the condensation or vaporisation of 1 kg of a fluid is the same - 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 square cross-section (having each side as
‘x’) is equal to 4x
C. Distillation process is not the same as evaporation
D. The effectiveness of nucleate boiling depends basically on the ease with which the bubbles are
formed and detached from the heating surface - Pick out the wrong statement?
A. The capacity of an evaporator is reduced by the boiling point elevation
B. Corrosive liquid is normally passed through the tubes in a shell and tube heat exchanger
C. Steam jet ejector is used for vapor compression in a thermal recompression evaporator
D. Heat sensitive materials should be concentrated in high pressure evaporators
