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4

By compounding the expansion of steam in two or more cylinders, the length of stroke

A. Does not change

B. Increases

C. Decreases

D. None of these

Correct Answer :

C. Decreases


Related Questions

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4

Fire tube boilers are limited to a maximum design working pressure of

A. 1 kg/cm

B. 6 kg/cm

C. 17 kg/cm²

D. 100 kg/cm²

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4

The diagram efficiency is the ratio of

A. Workdone on the blades to the energy supplied to the blades

B. Workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam

C. Energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam

D. None of the above

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4

De-Laval turbine is a

A. Single rotor impulse turbine

B. Multi-rotor impulse turbine

C. Impulse reaction turbine

D. None of these

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4

Hygrometry deals with the

A. Hygroscopic substances

B. Water vapour in air

C. Temperature of air

D. Pressure of air

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4

The compounding of turbines is done in order to

A. Reduce speed of rotor

B. Improve efficiency

C. Reduce exit losses

D. All of these

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4

The impulse reaction turbine has its driving force

A. As an impulsive force

B. As a reaction force

C. Partly as an impulsive force and partly as a reaction force

D. None of the above

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4

Water tube boilers are those in which

A. Flue gases pass through tubes and water around it

B. Water passes through the tubes and flue gases around it

C. Work is done during adiabatic expansion

D. Change in enthalpy

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4

When steam after doing work in the cylinder passes into a condenser, the engine is said to be a

A. Slow speed engine

B. Vertical steam engine

C. Condensing steam engine

D. Non-condensing steam engine

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4

In forced recirculation 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

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4

Curtis turbine is a

A. Simple reaction turbine

B. Velocity compounded turbine

C. Pressure compounded turbine

D. Pressure-velocity compounded turbine

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4

The ratio of heat actually used in producing the steam to the heat liberated in the furnace, is known as

A. Equivalent evaporation

B. Factor of evaporation

C. Boiler efficiency

D. Power of a boiler

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4

In a reaction turbine

A. The steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades

B. The expansion of steam takes place partly in the fixed blades and partly in the moving blades

C. The steam is expanded from a high pressure to a condenser pressure in one or more nozzles

D. The pressure and temperature of steam remains constant

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4

Calorific value of coal is of the order of

A. 200-400 kcal/ kg

B. 800-1200 kcal/ kg

C. 2000-4000 kcal/ kg

D. 5000-8000 kcal/ kg

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4

The high pressure and low pressure cylinders in a receiver type compound engine are regarded as having cranks

A. 180° to each other

B. 90° to each other

C. 0° to each other

D. None of these

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4

The cylinder dimensions of a compound engine may be designed on the basis of

A. Equal power developed in each cylinder for uniform turning moment

B. Equal initial piston loads on all pistons for obtaining same size of piston rod, connecting rod etc. for all cylinders

C. Equal temperature drop in each cylinder for economy of steam

D. All of the above

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4

Thermal efficiency of a thermal power plant is of the order of

A. 15 %

B. 20 %

C. 30 %

D. 45 %

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4

In a single acting steam engine

A. The steam is admitted on one side of the piston and one working stroke is produced during each revolution of the crankshaft

B. The steam is admitted, in turn, on both sides of the piston and one working stroke is produced during each revolution of the crankshaft

C. The steam is admitted on one side of the piston and two working strokes are produced during each revolution of the crankshaft

D. The steam is admitted, in turn, on both sides of the piston and two working strokes are produced during each revolution of the crankshaft

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4

The value of diagram factor depends upon

A. Initial conditions of steam

B. Back pressure

C. Initial pressure of steam

D. All of these

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4

The amount of water evaporated in kg per kg of fuel burnt is called

A. Evaporative capacity of a boiler

B. Equivalent evaporation from and at 100° C

C. Boiler efficiency

D. None of these

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4

In a boiler, the heat is lost

A. To dry flue gases

B. In moisture present in the fuel

C. To steam formed by combustion of hydrogen per kg of fuel

D. All of the above

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4

The ultimate analysis of fuel lists

A. Various chemical constituents, carbon, hydrogen, oxygen etc, plus ash as percents by volume

B. Various chemical constituents, carbon, hydrogen, oxygen, etc, plus ash as percents by weight

C. Fuel constituents as percents by volume of moisture, volatile, fixed carbon and ash

D. Fuel constituents as percents by weight of moisture, volatile, fixed carbon and ash

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4

The mechanical draught _________ with the amount of smoke.

A. Increases

B. Decreases

C. Does not effect

D. None of these

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4

An air preheater

A. Increases evaporative capacity of the boiler

B. Increases the efficiency of the boiler

C. Enables low grade fuel to be burnt

D. All of the above

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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)

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4

When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be

A. Choked

B. Under-damping

C. Over-damping

D. None of these

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4

The theoretical indicator diagram of a simple steam engine is based upon the assumption that

A. There is no pressure drop due to condensation

B. Steam is admitted at boiler pressure and exhausted at condenser pressure

C. The expansion (or compression) of the steam is hyperbolic

D. All of the above

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4

A double acting steam engine with a cylinder diameter of 190 mm and a stroke of 300 mm has a cut-off of 0.35. The expansion ratio for this engine is nearly

A. 1.05

B. 2.86

C. 6.65

D. 10.05

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4

Which of the following statement is correct?

A. A fire tube boiler occupies less space than a water tube boiler, for a given power.

B. Steam at a high pressure and in large quantities can be produced with a simple vertical boiler.

C. A simple vertical boiler has one fire tube.

D. All of the above

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4

Which of the following is a water tube boiler?

A. Lancashire boiler

B. Babcock and Wilcox boiler

C. Locomotive boiler

D. Cochran boiler

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4

The ratio of the clearance volume to the swept volume is called

A. Cut-off ratio

B. Expansion ratio

C. Clearance ratio

D. None of these