1. How can we differentiate Rankine cycle from Carnot cycle?
a) Heat addition process of Rankine cycle is reversible isothermal whereas heat addition process of Carnot cycle is reversible isobaric
b) Heat addition process of Rankine cycle is reversible isobaric whereas heat addition process of Carnot cycle is reversible isothermal
c) Heat addition process of Rankine cycle is reversible isentropic whereas heat addition process of Carnot cycle is reversible isothermal
d) Both cycles are identical except the working fluid used
Answer
Answer: b [Reason:] Heat addition process of Rankine cycle is reversible isobaric whereas heat addition process of Carnot cycle is reversible isothermal. This is one of the major differences in both the cycles.
2. What is the relation between efficiencies of Rankine cycle and Carnot cycle for the same pressure ratio?
a) (ηr) = (ηc)
b) (ηr) > (ηc )
c) (ηr) < (ηc )
d) none of the mentioned
Answer
Answer: c [Reason:] The relation between efficiencies of Rankine cycle and Carnot cycle for the same pressure ratio is given by,
(ηr) < (ηc ).
3. If Tm be the mean temperature of heat addition in Rankine cycle as shown in diagram,
what will the formula for efficiency of Rankine cycle?
a) (ηr) = ( T3 / Tm)
b) (ηr) = 1 – (T3 / Tm)
c) (ηr) = 1 – (T2 / Tm)
d) (ηr) = (T2 / Tm)
Answer
Answer: b [Reason:]The required formula becomes
(ηr) = 1 – (T3 / Tm).
4. The maximum efficiency of Rankine cycle (ηr) is the function of
a) the mean temperature of heat addition (Tm) only
b) the mean temperature of heat addition (Tm) and temperature of steam at the exit of the turbine
c) the mean temperature of heat addition (Tm) and temperature of steam at the entry of the turbine
d) the mean temperature of heat addition (Tm) and temperature of steam at exit of the condenser
Answer
Answer: a [Reason:] The maximum efficiency of Rankine cycle (ηr) is the function of
the mean temperature of heat addition (Tm) only.
5. What is the effect of superheated steam on efficiency of Rankine cycle?
a) efficiency of Rankine cycle decreases with increase in superheat of the steam
b) efficiency of Rankine cycle increases with increase in superheat of the steam
c) efficiency of Rankine cycle is not affected by change in superheat of the steam
d) none of the mentioned
Answer
Answer: b [Reason:] The effect of superheated steam on efficiency of Rankine cycle is that the efficiency of Rankine cycle increases with increase in superheat of the steam.
6. What is the effect of increase in pressure at which heat is added on the pump work in the Rankine cycle?
a) the pump work increases with increase in pressure of heat addition
b) the pump work decreases with increase in pressure of heat addition
c) the pump work does not change with increase in pressure of heat addition
d) the pump work either increases or decreases with increase in pressure of heat addition
Answer
Answer: a [Reason:] The effect of increase in pressure at which heat is added on the pump work in the Rankine cycle is that the pump work increases with increase in pressure of heat addition.
7. When the pressure at which heat is added in Rankine cycle increases, the moisture content at the turbine exhaust
a) increases
b) decreases
c) remains same
d) cannot say
Answer
Answer: a [Reason:] With an increase in the pressure at which heat is added in Rankine cycle increases, the moisture content at the turbine exhaust increases.
8. What is the condition for increasing the chances of corrosion of blades of turbine?
a) decrease in the pressure difference between which the Rankine cycle operates
b) increase in the pressure difference between which the Rankine cycle operates
c) both a and b
d) none of the mentioned
Answer
Answer: b [Reason:] The condition for increasing the chances of corrosion of blades of turbine is an increase in the pressure difference between which the Rankine cycle operates.
9. What is the maximum content of moisture allowed at the turbine exhaust in the steam power plant?
a) 50 %
b) 60 %
c) 30 %
d) 15 %
Answer
Answer: d [Reason:] The maximum content of moisture allowed at the turbine exhaust in the steam power plant is 15 %.
10. Which of these is a binary cycle?
a) Mercury-steam cycle
b) Mercury-water cycle
c) Mercury-Sodium cycle
d) None of the mentioned
Answer
Answer: a [Reason:] The binary cycle is mainly a Mercury-Steam cycle.
