Power Plant Engineering Multiple Choice Questions on “Mean Temperature of Heat Addition – 1”.
1. 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
Answer: a
Clarification: Efficiency = 1 – Tmin / Tm.
2. 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)
Answer: c
Clarification: Increasing condensor pressure decreases turbine exit temperature which in turn increases mean temperature of heat addition.
3. 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
Answer: d
Clarification: Practical analysis shows that Internal irreversibility of Rankine cycle depends upon above stated factors.
4. 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
Answer: a
Clarification: Efficiency = 1 – Tmin / Tm.
5. 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
Answer: d
Clarification: Pulverized coal also known as powdered coal or coal dust since it is as fine as face powder in cosmetic make-up.
6. What is caking in Power Plants?
a) making cakes of coal out of fine powders
b) a variety of free burning coals
c) coal produced from burning of wood in inert atmosphere
d) in boiler furnace some coals become plastic and form lumps or masses of coal
Answer: d
Clarification: When many bituminous coals are heated, they soften and form a plastic mass that swells and re solidifies into a porous solid.
7. Water gas is a mixture of ___________
a) CO2 and O2
b) O2 and H2
c) H2, N2 and O2
d) CO, N2 and H2
Answer: b
Clarification: Water gas is basically HHO that is H2 and O2.
8. Critical pressure of water is ___________
a) 1 kg / cm2
b) 100 kg / cm2
c) 155 kg / cm2
d) 217.7 kg / cm2
Answer: d
Clarification: The critical pressure of a substance is the pressure required to liquefy a gas at its critical temperature.
9. Coal used in power plant is also known as ___________
a) steam coal
b) charcoal
c) coke
d) soft coal
Answer: a
Clarification: Because this coal is used to generate steam.
10. The temperature to which air must be cooled in order to become saturated is the ___________
a) minimum temperature
b) dew point temperature
c) wet-bulb temperature
d) freezing point
Answer: b
Clarification: The dew point is the temperature at which the water vapour in air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates.