Thermodynamics Multiple Choice Questions on “Binary Vapor Cycles”.
1. Which of the following fluid can be used in place of water?
a) diphenyl ether
b) aluminium bromide
c) mercury
d) all of the mentioned
Answer: d
Clarification: These fluids are better than water in high temperature range.
2. Which of the following statement is true?
a) only mercury has been used in place of water
b) diphenyl ether decomposes at high temperatures
c) both of the mentioned
d) none of the mentioned
Answer: c
Clarification: Also aluminium bromide is a possibility which can be considered.
3. Mercury is a better fluid in high temperature range.
a) true
b) false
Answer: a
Clarification: This is because its vaporization pressure is relatively low even at higher temperatures.
4. Why is mercury unsuitable at low temperatures?
a) its saturation pressure becomes very high
b) its specific volume is very low at such a high pressure
c) both of the mentioned
d) none of the mentioned
Answer: d
Clarification: Its saturation pressure becomes very low and specific volume is very large.
5. In a binary cycle, ____ cycles with ____ working fluid are coupled.
a) two, same
b) two, different
c) three, same
d) three, different
Answer: b
Clarification: In a binary cycle, heat rejected by one can be utilized by other.
6. To vaporize one kg of water, ____ kg of mercury must condense.
a) 5-6
b) 6-7
c) 7-8
d) 8-9
Answer: c
Clarification: This depends on the properties of mercury and water.
7. When mercury cycle is added to the steam cycle,
a) the mean temperature of heat addition increases
b) efficiency decreases
c) maximum pressure is high
d) all of the mentioned
Answer: a
Clarification: The increase in the mean temperature of heat addition increases the efficiency and the maximum pressure is also low.
8. Initially in a reciprocating steam engine,
a) a binary cycle was used
b) steam was used in the high temperature
c) ammonia or sulphur dioxide was used in the low temperature range
d) all of the mentioned
Answer: d
Clarification: Steam from engine at higher temperature and pressure was used to evaporate sulphur dioxide or ammonia which operated in another cycle.
9. In a mercury-steam cycle, mercury cycle is called ____ and steam cycle is called ____
a) bottoming cycle, topping cycle
b) topping cycle, bottoming cycle
c) both are called bottoming cycle
d) both are called topping cycle
Answer: b
Clarification: The mercury-steam cycle represents a two-fluid cycle.
10. We can get a tertiary cycle if a sulphur dioxide cycle is added to mercury-steam cycle.
a) true
b) false
Answer: a
Clarification: In this three-fluid cycle, sulphur dioxide cycle is added in the low temperature range.