1. The overall efficiency noverall of a steam power plant is given by?
a) noverall = (power available at the generator terminals / (Fuel burning rate x Calorific Value of the fuel))
b) noverall = (power available at the generator terminals + (Fuel burning rate x Calorific Value of the fuel))
c) noverall = (power available at the generator terminals – (Fuel burning rate x Calorific Value of the fuel))
d) none of the mentioned
Explanation: The overall efficiency noverall of a steam power plant is given by,
noverall = (power available at the generator terminals / (Fuel burning rate x Calorific Value of the fuel)).
2. Which of the following shows the correct relation? (nboiler denotes efficiency of a boiler)
a) nboiler = (rate of energy absorption by water to form steam / rate of energy released by the combustion of fuel)
b) nboiler = (rate of energy absorption by water to form steam + rate of energy released by the combustion of fuel)
c) nboiler = (rate of energy absorption by water to form steam – rate of energy released by the combustion of fuel)
d) nboiler = (rate of energy absorption by water to form steam x rate of energy released by the combustion of fuel)
Explanation: The efficiency of a boiler is given by the following expression,
nboiler = (rate of energy absorption by water to form steam / rate of energy released by the combustion of fuel).
3. The mechanical efficiency of a turbine is given by? (ntm denotes the mechanical efficiency)
a) ntm = (brake output of the turbine x internal output of the turbine)
b) ntm = (internal output of the turbine / break output of the turbine)
c) ntm = (brake output of the turbine / internal output of the turbine)
d) ntm = (brake output of the turbine – internal output of the turbine)
Explanation: The expression for the turbine mechanical efficiency is given by,
ntm = (brake output of the turbine / internal output of the turbine).
4. If Q1 represents the rate of heat addition to the cycle and Wnet represents net cycle work output, the expression for net cycle heat rate is?
a) Q1 + Wnet
b) Q1 / Wnet
c) Q1 / (1/Wnet)
d) Q1 x Wnet
Explanation: The expression for the net cycle heat rate is given by,
Net cycle heat rate(HR) = Q1 / Wnet.
5. The generator efficiency n of the electric alternator is?
a) n = (electrical output at generator terminals / Brake output of the turbine)
b) n = (electrical output at generator terminals x Brake output of the turbine)
c) n = (electrical output at generator terminals / (1/ Brake output of the turbine))
d) none of the mentioned
Explanation: The generator efficiency of the electric alternator is defined as the ratio of electrical output at generator terminals to the brake output of the turbine.
6. Which of these is not an auxiliary equipment in a power plant?
a) Fans
b) Crushers
c) Galvanisers
d) Conveyors
Explanation: The auxiliary equipment in a power plant are those equipment which are driven by the electricity taken from the generated power of the plant.
7. Which of these shows the formula for the efficiencies of the auxiliaries n1?
a) n1 = (net power transmitted by the generator x gross power produced by the plant)
b) n1 = (net power transmitted by the generator / gross power input to the plant)
c) n1 = (net power transmitted by the generator / gross power produced by the plant)
d) n1 = (net power transmitted by the generator / gross power transferred by the plant)
Explanation: The auxiliary equipment or auxiliaries in a power plant are those equipment which are driven by the electricity taken from the generated power of the plant. Their efficiency is given by,
n1 = (net power transmitted by the generator / gross power produced by the plant).
8. What approximate percentage of energy in the fuel is converted to electricity?
a) 55%
b) 45%
c) 35%
d) 25%
Explanation: Only 34% of the energy stored in the fuel is converted to electricity & 66% is lost. The maximum loss of energy takes place in the condenser where heat is rejected to cooling water.
9. Heat rejection in a condenser is to?
a) cooled water
b) coolant
c) cooling water
d) none of the mentioned
Explanation: The maximum loss of energy takes place in the condenser where heat is rejected to cooling water. This is the loss due to heat to work energy conversion in the cycle or the loss due to second law.
10. Heat rate indicates?
a) heat added per unit volume
b) heat added per unit of work produced
c) heat added per unit of mass stored
d) heat added per unit area
Explanation: The parameter which readily affects the fuel economy is the heat rate which is inversely proportional to the efficiency, and hence the lower its value the better. It broadly indicates the heat added per unit of work produced.