Power Plant Engineering Multiple Choice Questions on “Regenerative Feedwater Heating”.
1. In an ideal regenerative cycle, heat input is at?
a) Boiler
b) Turbine
c) Condenser
d) Pump
Answer: a
Clarification: In a regenerative cycle, the heat input is at Boiler (from the flow chart of an ideal regenerative cycle).
2. In an ideal regenerative cycle, heat output is at?
a) Boiler
b) Turbine
c) Condenser
d) Pump
Answer: c
Clarification: In a regenerative cycle, the heat output is at the Condenser (from the flow chart of an ideal regenerative cycle).
3. In an ideal regenerative cycle, the work output is at?
a) Boiler
b) Turbine
c) Condenser
d) Pump
Answer: b
Clarification: In a regenerative cycle, the work output is at the Condenser (from the flow chart of an ideal regenerative cycle).
4. In an ideal regenerative cycle, the work input is at?
a) Boiler
b) Turbine
c) Condenser
d) Pump
Answer: d
Clarification: In a regenerative cycle, the work input is at the Condenser (from the flow chart of an ideal regenerative cycle).
5. What effect does the heating of feedwater by steam ‘bled’ from the turbine has on the Rankine Cycle?
a) it rankinises the Rankine Cycle
b) it carnotinises the Rankine Cycle
c) it reheats the Rankine Cycle
d) none of the mentioned
Answer: b
Clarification: The heating of feedwater by steam ‘bled’ from the turbine, known as regeneration, carnotinises the Rankine cycle.
6. What is the effect of increase in regeneration on steam rate?
a) steam rate increases
b) steam rate decreases
c) steam rate isindependent of regeneration
d) none of the mentioned
Answer: a
Clarification: More steam has to circulate per hour to produce unit shaft output.
7. If h1 & h10 are the enthalpies at the inlet & at the exhaust, s1 & s10 are the enthalpies at the inlet & exhaust, the mean temperature of heat addition, Tml with regeneration is?
a) (h1 + h10)/(s1 + s10)
b) (h1 + h10)/(s1 – s10)
c) (h1 – h10)/(s1 + s10)
d) (h1 – h10)/(s1 – s10)
Answer: d
Clarification: The expression for mean temperature of heat addition is given as,
T = (h1 – h10)/(s1 – s10).
8. If Q represents the heat input, P represents the heat output; the efficiency n in terms of Q & P is given by?
a) n = QP
b) n = (Q-P)/Q
c) n = (P-Q)/Q
d) n = Q/(Q-P)
Answer: b
Clarification: The expression of efficiency in terms of heat input & output is given by,
n = (Q-P)/Q.
9. If q represents the work output, r represents the work input, Q represents the heat input, the efficiency n in terms of q & r is given by?
a) n = (q-r)/Q
b) n = ( q+r)/Q
c) n = (qr)/Q
d) n = (qr x qr)/Q
Answer: a
Clarification: The efficiency in terms of work input, work output & heat input is given by,
n = (q-r)/Q.
10. What is the effect of increase in steam rate on boiler size?
a) boiler size increases
b) boiler size increases
c) boiler size is independent of steam rate
d) none of the mentioned
Answer: a
Clarification: Increase in steam rate increases by regeneration, i.e., more steam has to circulate per hour to produce unit shaft output. Hence, it increases boiler size.