Home
Current Affairs January 2024

What is the correct answer?

4

In a De-Laval nozzle expanding superheated steam from 10 bar to 0.1 bar, the pressure at the minimum cross-section (i. e. pressure at throat, p₂) will be

A. 3.3 bar

B. 5.46 bar

C. 8.2 bar

D. 9.9 bar

Correct Answer :

B. 5.46 bar


Related Questions

What is the correct answer?

4

A packaged boiler is one in which various parts like firing equipment, fans, feed pumps and automatic controls are

A. Supplied by same manufacturer loose and assembled at site

B. Supplied mounted on a single base

C. Purchased from several parties and packed together at site

D. Packaged boiler does not exist

What is the correct answer?

4

Fire tube boilers are

A. Internally fired

B. Externally fired

C. Internally as well as externally fired

D. None of these

What is the correct answer?

4

The Locomotive boiler has

A. 137 fire tubes and 44 superheated tubes

B. 147 fire tubes and 34 superheated tubes

C. 157 fire tubes and 24 superheated tubes

D. 167 fire tubes and 14 superheated tubes

What is the correct answer?

4

During polytropic process

A. Heat transfer takes place across cylinder walls

B. Work is done

C. Steam may be wet, dry or superheated after expansion

D. All of the above

What is the correct answer?

4

On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by

A. Horizontal straight line

B. Vertical straight line

C. Straight inclined line

D. Curved line

What is the correct answer?

4

The pressure of steam __________ while flowing through a nozzle.

A. Increases

B. Decreases

C. Remains constant

D. None of these

What is the correct answer?

4

Benson boiler requires

A. No drum

B. One drum

C. Two drums

D. Three drums

What is the correct answer?

4

The heat loss in a boiler takes place in the form of

A. Heat carried away by flue gases

B. Heat carried away by ash

C. Moisture present in fuel and steam formed by combustion of hydrogen in fuel

D. All of the above

What is the correct answer?

4

The fusible plug in small boilers is located

A. In the drum

B. In the fire tubes

C. Above steam dome

D. Over the combustion chamber

What is the correct answer?

4

In accelerated circulation type boiler

A. Heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum

B. Water is supplied in drum and through down comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam

C. Feed pump is employed to supplement natural circulation in water wall type furnace

D. Water is converted into steam in one pass without any recirculation

What is the correct answer?

4

The flow of steam is supersonic

A. At the entrance to the nozzle

B. At the throat of the nozzle

C. In the convergent portion of the nozzle

D. In the divergent portion of the nozzle

What is the correct answer?

4

Lancashire boiler is used where working pressure and power required are

A. Low

B. Moderate

C. High

D. None of these

What is the correct answer?

4

The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is

A. Less

B. More

C. Equal

D. May be less or more depending on temperature

What is the correct answer?

4

In a reaction turbine, when steam flows through the moving blades,

A. Pressure increases while velocity decreases

B. Pressure decreases while velocity increases

C. Pressure and velocity both decreases

D. Pressure and velocity both increases

What is the correct answer?

4

In reaction turbines, the axial thrust is due to

A. Pressure drop across the rotor

B. Change in axial velocity

C. Both (A) and (B)

D. None of these

What is the correct answer?

4

It is required to produce large amount of steam at low pressure. Which boiler should be used?

A. Pulverised fuel fired boiler

B. Cochran boiler

C. Lancashire boiler

D. Babcock and Wilcox boiler

What is the correct answer?

4

The isentropic enthalpy drop in moving blade is two-third of the isentropic enthalpy drop in fixed blades of a turbine. The degree of reaction will be

A. 0.4

B. 0.56

C. 0.67

D. 1.67

What is the correct answer?

4

At which pressure the properties of water and steam become identical

A. 0.1 kg/cm²

B. 1 kg/cm²

C. 100 kg/cm²

D. 225.6 kg/cm²

What is the correct answer?

4

The steam temperature with increase in load in case of a boiler fitted with radiation superheater

A. Increases

B. Decreases

C. Remain unaffected

D. First increases and then decreases

What is the correct answer?

4

The economiser is used in boilers to

A. Increase thermal efficiency of boiler

B. Economise on fuel

C. Extract heat from the exhaust flue gases

D. Increase flue gas temperature

What is the correct answer?

4

Efficiency of Rankine cycle can be increased by

A. Decreasing initial steam pressure and temperature

B. Increasing exhaust pressure

C. Decreasing exhausts pressure

D. Increasing the expansion ratio

What is the correct answer?

4

The ratio of the actual vacuum to the ideal vacuum in a condenser is called

A. Condenser efficiency

B. Vacuum efficiency

C. Nozzle efficiency

D. Boiler efficiency

What is the correct answer?

4

Degree of reaction is defined as the ratio of

A. Heat drop in fixed blades to the heat drop in moving blades

B. Heat drop in moving blades to the heat drop in fixed blades

C. Heat drop in moving blades to the heat drop in fixed blades plus heat drop in moving blades

D. Heat drop in fixed blades plus heat drop in moving blades to the heat drop in moving blades

What is the correct answer?

4

In fire tube boilers

A. Water passes through the tubes which are surrounded by flames and hot gases

B. The flames and hot gases pass through the tubes which are surrounded by water

C. Forced circulation takes place

D. None of these

What is the correct answer?

4

The cylinder condensation or missing quantity may be reduced by

A. The efficient steam jacketing of the cylinder walls

B. Superheating the steam supplied to the engine cylinder

C. Keeping the expansion ratio small in each cylinder

D. All of the above

What is the correct answer?

4

The stage efficiency (ηS) is given by (where ηB = Blading efficiency, and ηN = Nozzle efficiency)

A. ηS = ηB × ηN

B. ηS = ηB / ηN

C. ηS = ηN / ηB

D. None of these

What is the correct answer?

4

The ratio of heat utilised to produce steam and the heat liberated in furnace is known as

A. Boiler effectiveness

B. Boiler evaporative capacity

C. Factor of evaporation

D. Boiler efficiency

What is the correct answer?

4

The critical pressure ratio (p₂/p₁) is given by

A. (p₂/p₁) = [2/(n - 1)] n/(n + 1)

B. (p₂/p₁) = [2/(n + 1)] n/(n-1)

C. (p₂/p₁) = [(n - 1)/2] n + (1/n)

D. (p₂/p₁) = [(n + 1)/2] n - (1/n)

What is the correct answer?

4

Which of the following statement is wrong?

A. The factor of evaporation for all boilers is always greater than unity.

B. The amount of water evaporated in kg per kg of fuel burnt is called equivalent evaporation from and at 100° C.

C. The ratio of heat actually used in producing the steam to the heat liberated in the furnace is called boiler efficiency.

D. None of the above

What is the correct answer?

4

The efficiency of the plant __________ with the mechanical draught.

A. Increases

B. Decreases

C. Remains constant

D. None of these