While the total emissivity of a perfect black body is unity, the same for a real body is__________________?
A. 0
B. 1
C. > 1
D. Between 0 and 1
Month: March 2019
Crystal size in a continuous crystalliser depends upon the___________________?
Crystal size in a continuous crystalliser depends upon the___________________?
A. Rate of heat transfer
B. Degree of turbulence
C. Degree of super-saturation
D. All A., B. and C
Boiling of milk in an open vessel is an example of ______________ boiling?
Boiling of milk in an open vessel is an example of ______________ boiling?
A. Film
B. Sub-cooled
C. Saturated nucleate
D. None of these
Black liquor generated during paper manufacture is concentrated in a___________________?
Black liquor generated during paper manufacture is concentrated in a___________________?
A. Single effect evaporator
B. Single effect evaporator followed by a crystalliser
C. Multiple effect evaporator
D. Multiple effect evaporators followed by a crystalliser
What is Nusselt number ?
What is Nusselt number ?
A. CP. μ/k
B. hD/k
C. h. CP/μ
D. CP. μ/h
In the equation Q = UAΔt; Δt is_________________________?
In the equation Q = UAΔt; Δt is_________________________?
A. Geometric mean temperature difference
B. Arithmetic mean temperature difference
C. Logarithmic mean temperature difference
D. The difference of average bulk temperatures of hot and cold fluids
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 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately ?
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 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately ?
A. 32
B. 37
C. 45
D. 50
Graetz number is given by__________________?
Graetz number is given by__________________?
A. mCp/kL
B. kL/mCp
C. mCp/kμ
D. kμ/mCp
Reynold’s analogy states that_________________?
Reynold’s analogy states that_________________?
A. Nst α f
B. Nst α NRe
C. NNu α f
D. NRe α f
Which of the following has the minimum thermal conductivity ?
Which of the following has the minimum thermal conductivity ?
A. Nitrogen
B. Steel
C. Carbon black
D. Tar