This set of Thermal Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Surface Condensers”.
1. Which of the following is NOT a type of surface condenser?
a) Regenerative type
b) Evaporative type
c) Inverted-flow type
d) Ejector type
View Answer
Explanation: Ejector condenser is a type of jet condenser and not a surface condenser. Surface condensers are classified into down-flow type, central-flow type, inverted-flow type, regenerative type and evaporative type.
2. Which of the following condensers is also called cross-surface condenser?
a) Inverted-flow type
b) Evaporative type
c) Down-flow type
d) Central-flow type
View Answer
Explanation: In down-flow type surface condensers the direction of steam flow is perpendicular to the direction of flow of water, hence they are also called cross-surface condensers. Exhaust stream passes over a series of tubes having cold water flow in it, and thus condenses.
3. Radial flow of steam is observed in _____
a) down-flow type surface condenser
b) central-flow type surface condenser
c) regenerative type surface condenser
d) evaporative Surface condenser
View Answer
Explanation: In central-flow type surface condenser, the suction pipe of air extraction pump is located at the center of the tubes. This results in radial flow of the steam. In this case the pressure drop of steam is less.
4. Which of the following condensers has air suction located at the top?
a) Down-flow type surface condenser
b) Central-flow type surface condenser
c) Inverted-flow type surface condenser
d) Evaporative condenser
View Answer
Explanation: Inverted-flow type surface condenser has air suction at the top. The steam enters the condenser shell from the bottom, it rises up and then flows down. The condensate is collected at the bottom.
5. In Inverted-flow type surface condensers, where is the pipe of condensate extraction pump located?
a) At the top of the condenser shell
b) At the bottom of the condenser shell
c) Near the middle portion of the condenser shell
d) Between the middle and the top portion of the condenser shell
View Answer
Explanation: The steam enters the condenser from the bottom, it rises to the top and then flows down to the bottom getting condensed the whole time. The condensate is collected at the bottom of the condenser shell; hence the pipe of condensate extraction pump is located at the bottom of the condenser shell.
6. In regenerative type surface condensers, the condensate before being used as feed water for the boiler is heated using the entering exhaust steam.
a) True
b) False
View Answer
Explanation: In case of regenerative type surface condensers, the condensate is passed though the entering exhaust steam so as to heat it before it goes back to the boiler as feed water. A regenerative method of heating of condensate is used in this condenser.
7. _____ works best when the availability of cooling water is limited.
a) Down-flow type surface condenser
b) Regenerative type surface condenser
c) Inverted-flow type surface condenser
d) Evaporative condenser
View Answer
Explanation: In evaporative condensers, the quantity of cooling water required is less as the circulating water is caused to evaporate under small partial pressure. Hence, it will work best when the availability of cooling water is low or limited.
8. In down-flow type surface condensers, the plate that separates the water box into two sections is called _____
a) baffle plate
b) separating plate
c) partitioning plate
d) divider
View Answer
Explanation: Baffle plate acts as the partition between the two sections in the water box. Cold water enters into the condenser through one section and leaves through the other. Baffle plate ensures that the inlet water doesn’t come in contact with the water leaving the water box.
9. Which of the following statements is FALSE about down-flow type surface condensers?
a) Cold water flows through the tubes and the exhaust steam flows around the tubes
b) The condenser shell is usually made cylindrical
c) Cold water doesn’t come in direct contact with the exhaust steam
d) It is also called barometric condenser
View Answer
Explanation: High level counter flow type jet condenser is also known as barometric condenser. Down-flow type surface condensers are also called cross-surface condenser since the flow of exhaust steam is at right angle to the direction of the water flow.
10. Where is the suction pipe of the air suction pump located in central-flow type surface condensers?
a) At the centre of the tubes
b) At the top of condenser shell
c) At the bottom of the condenser shell
d) Near the pipe of condensate extraction pump
View Answer
Explanation: In central-flow type surface condensers, the suction pipe of the air suction pump is located at the centre of the tubes. Due to this placement of the pipe of air suction pump, the exhaust stema flows radially.
Sanfoundry Global Education & Learning Series – Thermal Engineering
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