Minimum thermal efficiency of a steam boiler may be around ____________________ percent ?

Related Mcqs:

1. White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is_______?

   A. Tar
   B. Sulphide Coke
   C. Coke Oven Gas
   D. Pulverised coke

   Submitted by: Muhammad Mutsadiq Umer

2. Dryness factor of steam is defined as the ratio of the mass of vapor in the mixture to the mass of the mixture. Dryness factor of steam is measured by a _______________ calorimeter ?

   A. Bomb
   B. Throttling
   C. Junker’s
   D. Boy’s

3. Which of the following identities can be most easily used to verify steam table data for superheated steam ?

   A. (∂T/∂V)S = (∂p/∂S)V
   B. (∂T/∂P)S = (∂V/∂S)P
   C. (∂P/∂T)V = (∂S/∂V)T
   D. (∂V/∂T)P = -(∂S/∂P)T

4. Dryness fraction of wet steam is defined as the ratio of mass of vapour in the mixture to the mass of mixture ______________ calorimeter is not used for measuring the dryness fraction of steam?

   A. Bomb
   B. Separating
   C. Bucket
   D. Throttling

5. Steam undergoes isentropic expansion in a turbine from 5000 kPa and 400°C (entropy = 6.65 kJ/kg K) to 150 kPa) (entropy of saturated liquid = 1.4336 kJ/kg. K, entropy of saturated vapour = 7.2234 kJ/kg. K) The exit condition of steam is_______________?

   A. Superheated vapour
   B. Partially condensed vapour with quality of 0.9
   C. Saturated vapour
   D. Partially condensed vapour with quality of 0.1

6. Thermal efficiency of a Carnot engine can approach 100%, only when the temperature of the__________________?

   A. Cold reservoir approaches zero
   B. Hot reservoir approaches infinity
   C. Either A. or B
   D. Neither A. nor B

7. Which of the following has the least thermal efficiency ?

   A. Steam engine
   B. Carnot engine
   C. Diesel engine
   D. Otto engine

8. The following heat engine produces power of 100,000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is____________________?

   A. 100,000 kW
   B. 160,000 kW
   C. 200,000 kW
   D. 320,000 kW

9. In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about _____________ percent?

   A. 0.25
   B. 0.5
   C. 0.75
   D. 1

10. Tri-sodium phosphate is used in boiler water treatment to reduce____________________?

    A. Turbidity
    B. Caustic embrittlement
    C. Suspended silica
    D. Dissolved oxygen