1. Which of the following methods can be used to increase efficiency of a Brayton cycle?
a) Regeneration
b) Increasing pressure ratio
c) Heat exchanger
d) All of the mentioned
Explanation: A heat exchanger that acts as a counter-flow energy recovery device positioned within the supply and exhaust air streams of an air handling system, in order to recover the waste heat.
2. For the same maximum pressure and heat input, the most efficient cycle is?
a) Brayton cycle
b) Carnot cycle
c) Rankine cycle
d) Dual cycle
Explanation: Efficiency of a Brayton cycle is directly proportional to pressure ratio
3. The compression ratio is the ratio of ____________
a) Swept volume to total volume
b) Total volume to swept volume
c) Total volume to clearance volume
d) None of the mentioned
Explanation: According to definition, compression ratio is the ratio of swept volume to total volume
4. A Sterling engine uses an energy source whose temperature is 727°C and an energy sink whose temperature is 27°C. How much heat must be added to the engine to produce 1 unit of work?
a) 1.10
b) 1.19
c) 1.43
d) 2.0
Explanation: Since the Sterling engine is totally reversible, its thermal efficiency is the same as that of a Carnot engine, η = 1 – Tl / Th = 0.7. Now, the definition of the thermal efficiency gives Qin / Wout = 1 / η = 1.43.
5. Which of the following is not a component of Brayton cycle?
a) Compressor
b) Combustion Chamber
c) Turbine
d) Pump
Explanation: Pump is used in Rankine cycle to circulate water from Condenser to Boiler.
6. For a given value of mean temperature of heat addition(Tm) is?
a) efficiency of Rankine is more if turbine exit temperature(Tmin) is less
b) efficiency of Rankine is less if turbine exit temperature(Tmin) is less
c) efficiency does not depend on turbine exit temperature
d) none of the mentioned
Explanation: Efficiency = 1 – Tmin / Tm.
7. Mean temperature of heat addition can be increased by?
a) decreasing the amount of heat added
b) increase the amount of heat added
c) increase condensor pressure
d) decreasing Turbine Inlet Temperature(TIT)
Explanation: Increasing condensor pressure decreases turbine exit temperature which in turn increases mean temperature of heat addition
8. Internal irreversibility of Rankine cycle is caused by?
a) fluid friction
b) throttling and mixing
c) expansion and compression process are quite rapid
d) all of the mentioned
Explanation: Practical analysis shows that Internal irreversibility of Rankine cycle depends upon above stated factors.
9. Which of the following statement is true?
a) efficiency is directly proportional to mean temperature of heat addition
b) efficiency is inversely proportional to mean temperature of heat addition
c) efficiency is exponential function of mean temperature of heat addition
d) efficiency does not depend on mean temperature of heat addition
Explanation: Efficiency = 1 – Tmin / Tm.
10. Pulverized coal is ____________
a) coal free from ash
b) non-smoking coal
c) coal which bums For long time
d) coal broken into fine particles
Explanation: Pulverized coal also known as powdered coal or coal dust since it is as fine as face powder in cosmetic make-up.