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This quiz contains multiple-choice problems on heat transfer mechanisms, pressure drop calculations, bed temperature profiles and heat transfer coefficients of packed and fluidised beds.
Packed bed reactors are __ heat exchangers.
Indirect contact
Direct contact
Tubular
Plate-type
Which one of the following is not a use of packed bed?
Regenerators
Stripping
Mixing
Solid matrix heat exchangers
Why is heating or cooling required in packed beds if we do not use them as heat exchangers?
To cool exothermic reactions
To cool water by using ice as pellets
To cool petroleum by using ice as pellets
To heat exothermic reactions
It has been discovered that wall-cooled operations on packed beds show more effective heat transfer rates than wall-heated operations. True or false?
True
False
Both wall heated packed beds and wall cooled packed beds have more or less the same correlation. True or false?
True
False
Why are packed-bed heat exchangers the same as direct contact-type heat exchangers?
Because they create heavy mixing
Uses two fluids to transfer heat by dissolving into each other
Gas-liquid system where they are brought to direct contact
Gas-gas system where they are brought to direct contact
Which of the following is not a valid operation of packed bed reactors?
Shell-and-tube setup
Indirect contact setup
Feedwater heater
Direct contact setup
For an endothermic reaction, which of the following operations is best suited to support the reaction?
Shell and tube with hot fluid in shell and packed bed in tube
Shell and tube with cold fluid in shell and packed bed in tube
Shell and tube with hot fluid in tube and packed bed in shell
Shell and tube with cold fluid in tube and packed bed in shell
For an exothermic reaction, which of the following operations is best suited to support the reaction?
Shell and tube with hot fluid in shell and packed bed in tube
Shell and tube with cold fluid in shell and packed bed in tube
Shell and tube with hot fluid in tube and packed bed in shell
Shell and tube with cold fluid in tube and packed bed in shell
As indirect contact heat exchangers, packed beds have __ fluid flow.
Continuous
Constant
Intermittent
Reversing
Packed beds are one of the most common heat exchangers because of their very
High bed side heat transfer coefficient
High wall side heat transfer coefficient
High conductivity
Low heat transfer rate
In a packed bed shell-and-tube heat exchanger, the pellets are usually kept
At tube side
At shell side
At any side as required
At floor of the shell
The temperature profile in a packed bed reactor surrounded by a cooling liquid is
Fully parabolic
Parabolic near the walls
Flat at the centre
Concave downward near the walls and upward at the centre
The velocity profile in a packed bed reactor is
Fully parabolic
Parabolic near the walls
Flat at the centre
Concave downward near the walls and upward at the centre
The pressure drop in a packed bed __ for a given length.
Is constant
Exponentially increases
Parabolically increases
Linearly increases
