This set of Heat Transfer Operations Multiple Choice Questions & Answers (MCQs) focuses on “Direct Contact Condensers”.
1. Tubular condensers used in power plant to condense exhaust steam are known as ____________
a) Surface Condenser
b) Spray Condenser
c) Baffled column
d) Packed column
View Answer
Explanation: These tubular condensers are called surface condensers because they act as a barrier to the exhaust surface and hence condense it, thus it their cool surface that most of the condensation occurs.
2. Which one of the following is not a direct contact condenser?
a) Spray
b) Baffled column
c) Packed column
d) Shell and tube
View Answer
Explanation: The different types direct contact condensers are –
- The Spray Condenser
- The Baffled Column
- The Packed Column
- The Jet Condenser
- The Sparge Pipe
3. The condenser is one in which the coolant is not brought into contact with the vapour. Which one of the following is one of them?
a) Packed Column
b) Baffled shell and tube Column
c) Jet Condenser
d) Spray Condenser
View Answer
Explanation: The baffled column has a shell in which the hot fluid flows and the tubes carrying the coolant, condensation occurs at the surface of the tubes. Hence the coolant does not come into direct contact.
4. Which one of the following condenser matches to this description-‘The nozzles and vessel are designed to produce a fine spray of liquid to give a large interfacial area for heat transfer and a long enough residence time of liquid droplets in the vessel’?
a) Spray Column
b) Tray
c) Packed
d) Baffled
View Answer
Explanation: The spray column best matches this description as is visible from the given figure.
5. Which one of the following condenser matches to this description-‘This condenser is similar to the spray condenser, with the only difference that the coolant is directed to flow over a series of trays in a column’?
a) Spray Column
b) Tray
c) Packed
d) Baffled
View Answer
Explanation: The baffled column is as shown –
It has trays that obstruct the direct fall of the coolant and also increases the residence time of the coolant, hence increasing the efficiency of the condenser.
6. A ___________ consists of tightly-packed cold metal rings where heat transfer with vapour stream occurs and the vapour is condensed to its way upward.
a) Spray Column
b) Tray Column
c) Packed Column
d) Baffled Column
View Answer
Explanation: The packed column can be represented as –
where the hot air comes directly in contact with the substance or the cold material, which condenses the vapour and releases the dry gas from top.
7. Which of the following direct contact condenser has the maximum pressure drop as compared to other condensers?
a) Spray Column
b) Tray Column
c) Packed Column
d) Baffled Column
View Answer
Explanation: The major and governing demerit of a packed column condenser is that the pressure drop is in such setups are much higher than the other direct-contact condensers available in the market. The packed column Condenser looks like
8. Which one of the following condenser matches to this description-‘This condenser uses a jet of coolant liquid forced into a hot vapour stream, usually with the objective of de-superheating the vapour and hence condensing it’?
a) Jet Condenser
b) Tray Column
c) Packed Column
d) Baffled Column
View Answer
Explanation: The jet condenser can be represented as –
The diagram best explains the description as we see a jet of coolant liquid forced into a hot vapour stream, de-superheating the vapour and hence condensing it.
9. In a jet condenser, the liquid is usually injected in __________ to the vapour.
a) Counter-flow
b) Co-current flow
c) Haphazard flow
d) Oscillating flow
View Answer
Explanation: The liquid is injected from the top and the gas is fed from the bottom, hence the overall setup is a counter-flow setup of condenser.
10. The __________ consists of a pipe with holes for injecting bubbles of vapour into a pool of cold liquid.
a) Jet Condenser
b) Sparge pipe condenser
c) Packed Column
d) Baffled Column
View Answer
Explanation: This condenser is total opposite to that of a spray column wherein the gas to be condensed is passed into the coolant as bubbles which condense and gather at the surface of the coolant.
11. ____________ is an unstable condition in a condenser when the vapour flow is such that the downward flow of condensate is interrupted and held up.
a) Overflowing
b) Flooding
c) Clogging
d) Flogging
View Answer
Explanation: Flooding is the condition when the condensation has occurred beyond the holding capacity of the condenser, technically said – it is an unstable condition in a condenser when the vapour flow is such that the downward flow of condensate is interrupted and held up.
12. Which one of the following pairs has similar working principles?
a) Spray and sparged
b) Sparged and baffled
c) Spray and Baffled
d) Tray and sparged
View Answer
Explanation: The spray column and the baffled column are totally similar except that in baffled column there exist some blockage in the path of falling coolants.
Sanfoundry Global Education & Learning Series – Heat Transfer Operations.
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