This set of Thermal Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Classification of Steam Condensers”.
1. Steam condenser converts steam into water.
Explanation: Steam condenser is a device which converts steam into water or in which steam is condensed into water. The heat rejected by the steam during condensation is absorbed by cooling water.
2. Steam condensers help in maintaining high back pressure on the exhaust side of the piston of a steam engine.
Explanation: Steam condensers maintain very low back pressure at the exhaust side of the piston of a steam engine (or a turbine). This improves the quality of expansion of steam, steam expands to a greater extent and turbine efficiency is increased.
3. Sub-atmospheric pressure is also called _____
a) Gauge pressure
b) Absolute pressure
c) Vacuum pressure
d) High altitude pressure
Explanation: Sub-atmospheric pressure is vacuum pressure. Sub-atmospheric pressure is measured as the pressure depression below atmospheric pressure. Absolute pressure is measure taking perfect vacuum as reference.
4. Which of the following is NOT an element of a steam condensing plant?
a) Supply of cooling water
d) Wet air pump
Explanation: A steam condensing plant consists of a condenser, supply of cooling water, hot well, wet air pump and an arrangement for recooling of cooling water (for surface condensers). Hot well is where the condensate is discharged.
5. Discharging condensate to hot well improves plant efficiency because _____
a) condensate is not wasted
b) condensate cools down faster in the hot well
c) feed water for boiler is taken from the hot well
d) it increases the pressure in the hot well
Explanation: When the condensate is discharged into the hot well, the temperature of the water inside the hot well increases as it absorbs heat from the hot condensate. Since, the feed water temperature for the boiler is increased, the overall plant efficiency is increased.
6. Steam condensers are classified into _____
a) jet condensers and fast condensers
b) jet condensers and surface condensers
c) high condensers and surface condensers
d) slow condensers and jet condensers
Explanation: Condensers are mainly classified into two categories – Jet condensers and surface condensers. In case of jet condensers, the cooling water comes in direct contact with the exhaust steam while in surface condensers the cooling water and exhaust steam does not come in direct contact.
7. Cooling water is sprayed into the exhaust steam in _____
a) steam condensers
b) surface condensers
c) jet condensers
d) jet condensers and high condensers
Explanation: Usually in jet condensers, the cooling water is sprayed into the exhaust steam. This provokes rapid condensation of the steam. It can be observed that in jet condensers cooling water comes in direct contact with the exhaust steam.
8. Which of the following statements is TRUE about single-pass condenser?
a) It is a type of jet Condenser
b) The flow of water is in one direction only
c) The water flows in one direction through some tubes and returns through the remainder
d) It is not used to condense steam
Explanation: A single-pass condenser is a type of surface condenser. In this water flows in only one direction through the tubes. The cooling water does not come in direct contact with the exhaust steam.
9. Which of the following statements is FLASE about steam condensers?
a) Jet condensers are cheaper than surface condensers
b) Cooling water comes direct contact with the exhaust steam in jet condensers
c) Cooling water does not come in direct contact with exhaust steam in surface condensers
d) Jet condensers are further classified into single-pass and double-pass condensers
Explanation: Single-pass and Doubles-pass condensers belong to the category of surface condensers. In both type of condensers, the steam passes around tubes containing cooling water. The cooling water does not come in direct contact with the steam.
10. Which of the following statements is FALSE about double-pass condensers?
a) The water flows in one direction through some tubes and returns through the remainder
b) Exhaust steam flows through the tubes, while cooling water passes over the outer surface of the tubes
c) It is a type of surface condenser
d) Cooling water doesn’t come in contact with the exhaust steam
Explanation: Double-pass condensers are a type of surface condensers. Cooling water flows through the tubes and exhaust steam passes over the outer surface of the tubes. The water in the tubes flows in one direction through some tubes and returns through the remainder.
Sanfoundry Global Education & Learning Series – Thermal Engineering
To practice all areas of Thermal Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.
Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!