Diploma Thermal and Automobile Engineering Board Exam Answer key Unit 1

Diploma Thermal and Automobile Engineering Board Exam Answer key

Subject : Thermal & Automobile Engineering         Scheme : M

Unit – 1: Thermal power plant, steam Turbines and condenser, Refrigeration & Air

                                                Answer key 2/3 marks

  1. State two merits & demerits of thermal power plant
  • The plant life is more when compared to diesel power plant
  • The unit capacity of thermal power plant is more.
  • There is no transmission losses in thermal power plant since they are located near load centers.
  1. Define condenser

Condenser is a heat exchanging apparatus used to condense substance in a gaseous state to its liquid state by cooling. 

  1. State the necessity for compounding and types of compounding of steam turbines.
  • Compounding of steam turbine is used to reduce the rotor speed. It is the process by which rotor speed come to its desired value. A multiple system of rotors are connected in series keyed to a common shaft and the steam pressure or velocity is absorbed in stages as it flows over the blades. Generally, three different types of compounding are used to reduce the rotor speed of steam turbine.
  1. Velocity Compounding
  2. Pressure Compounding
  3. Pressure Velocity Compounding
  4. State the advantages of fluidized bed combustion.
  • high fuel flexibility, including the capability of using fuels with a high content of sulfur or ash;
  • the capability for firing low-grade fuels, e.g., biomass, refuse-derived fuels, and wastes, and for co-firing different types of fuels
  •  intense heat transfer characteristics, allowing for a compact boiler arrangement
  1. Draw the P-V diagram and T.S. diagram of a modified rankine cycle and indicate the various process involved in the cycle.

6. State the function of electrostatic precipitator

An electrostatic precipitator (ESP) is defined as a filtration device that is used to remove fine particles like smoke and fine dust from the flowing gas. It is the commonly used device for air pollution control. They are used in industries like steel plants, thermal energy plants.

  1. Define vacuum efficiency of a condenser.

Vacuum efficiency of actual vacuum present at the steam inlet to the maximum vacuum obtained in perfect condensing plant.

  1. State the difference between impulse turbine & reaction turbine.

Impulse Turbines

  • In impulse turbine steam flows through the nozzle and impinges in moving blades.
  • The steam hits on the buckets with Kinetic energy.
  • The steam pressure remains constant.
Reaction turbines:
  • Steam flows initially from guide mechanism and then from moving blades.
  • Steam glides over moving blades.
  • Steam pressure is reduced during its flow.
  1. State the sources of air present in condenser.

(i) Leakage of air from atmosphere at the joints of the parts which are at pressure less than atmospheric pressure.

(ii) Air is coming from the boiler along with steam. This air enters in the dissolved form in the feed water.

(iii) In case of jet condenser, quantity of air accompanies the injection of water.


  1. What are the elements of a condensing plant.
  1. 1. Condenser.
  2. Air extraction pump.
  3. Condensation extraction pump.
  4. Circulating pump.
  5. Cooling tower.
  6. Define C.O.P

The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work required.

  1. What is the function of a cyclone separator.

Cyclonic separation is a method of removing particulates from an air, gas or liquid stream, without the use of filters, through vortex separation. When removing particulate matter from liquid, a hydrocyclone is used; while from gas, a gas cyclone is used. Rotational effects and gravity are used to separate mixtures of solids and fluids. The method can also be used to separate fine droplets of liquid from a gaseous stream.

  1. State the difference between vapour compression and vapour absorption system of refrigeration.

14. Write the uses of cyclone separator

  •     Cyclone separator is used to remove dust particles from flue gases of the thermal power plant 
  1. Define COP of a refrigerator.

The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work required.

  1. Classify the types of condenser

           There are two types of condensor

  1.                 jet Condensor                                 2. Surface Condensor

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