# Thermodynamics Questions and Answers – Thermodynamics of Coupled Cycles

This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Thermodynamics of Coupled Cycles”.

1. The efficiency of a binary cycle is given by(here E=efficiency)
a) E = (1-E1)(1-E2)
b) E = 1 – (1-E1)(1-E2)
c) E = 1 / (E1-1)(E2-1)
d) none of the mentioned

Explanation: Here E1 is the efficiency of topping cycle and E2 is the efficiency of bottoming cycle.

2. For n cycles, overall efficiency would be
a) E = (1-E1)(1-E2)(1-E3)……(1-En) – 1
b) E = 1 / (1-E1)(1-E2)(1-E3)……(1-En)
c) E = (1-E1)(1-E2)(1-E3)……(1-En)
d) E = 1 – (1-E1)(1-E2)(1-E3)……(1-En)

Explanation: Hence we can say total loss = product of losses in all cycles.

3. By combining two cycles in series, we can get high combined efficiency even if the individual efficiencies are low.
a) true
b) false

Explanation: Such a high efficiency cannot be achieved by a single cycle.

4. How can we generate required power and required quantity of steam in a single process?
a) by modifying initial steam pressure
b) by modifying exhaust pressure
c) both of the mentioned
d) none of the mentioned

Explanation: We require modification in both the pressures.

5. In a back pressure turbine,
a) exhaust steam from turbine is used for process heating
b) the process heater replaces the condenser of Rankine cycle
c) exhaust pressure from turbine is the desired saturation pressure
d) all of the mentioned

Explanation: In a back pressure turbine we modify both initial steam pressure and exhaust pressure.
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6. A cogeneration plant produces,
a) power
b) process heat
c) both power and process heat
d) none of the mentioned

Explanation: In cogeneration plant, both power and process heat are produced.

7. In a by-product power cycle,
a) the basic need is power produced and process steam is a by-product
b) the basic need is process steam and power produced is a by-product
c) both process steam and power is the basic need
d) both process steam and power is a by-product

Explanation: Here, power produced is a by-product and the basic need is process steam.

8. In a by-product power cycle, condenser losses is ____
a) high
b) low
c) zero
d) infinity

Explanation: In a normal steam plant, this is the biggest loss but in a by-product power cycle it is zero.

9. The fraction of energy utilized in a by-product power cycle is ____
a) very high
b) very low
c) zero
d) infinity

Explanation: The reason being the condenser losses is zero.

10. The power available from back pressure turbine through which the heating steam flows is very less.
a) true
b) false

Explanation: The reason being relatively high back pressure or maybe small heating requirement.

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