Thermal shock produced by cooling is more dengerous/deleterious than that produced by heating a surface, because of the reason that

In self cooled motors the cooling time constant is about ______ than the heating time constant because cooling conditions are worse at standstill.

A

2 to 3 times greater

B

3 to 4 times greater

C

4 to 5 times greater

D

none of the above

In condensers used in thermal power plants, steam is normally used in shell side and cooling water on the tube side, because of the reason that

A

Compared to the mass flow rate of cooling water, the rate of condensation of steam is invariably smaller

B

Maintaining vacuum on tube side is more difficult than that on the shell side

C

Water velocity can be increased conveniently to increase the overall heat transfer co-efficient because of its lower specific volume compared to steam

D

Condenser can act as a storage unit for condensed steam

L is older than M and taller than N. O is younger than P, older than N and shorter than Q. R is older than S, younger than N, shorter than S and taller than Q. S is older than L, M, O, P, Q, R and S is necessarily false?

A

O is the shortest of the group.

B

N is the second tallest of the group.

C

L is the tallest of the group.

D

Q is the third oldest of the group.

There are five statements given below: i. karim earns more than Rahim but less than Raihan ii. Tarique earns more than Farid iii. Rahim earns more than Rariq iv. Raihan and Rarique earn equal amounts v. Farid earns the least amount which of the above statements prove that Tarique earns more money than Rafiq?

A

I, II and III

B

II, III and IV

C

III, IV and V

D

I, III and IV

In heating the ferromagnetic material by induction heating, heat is produced due to

A

Induced current flow through the charge

B

Hysteresis loss taking place below Curie temperature

C

Due to hysteresis loss as well as eddy current loss taking place in the charge

D

None of the above factors

Noise produced by cooling fans (employed in air cooled heat exchangers or cooling tower) is mainly caused due to the turbulence created by blade passage through air. It can be reduced by use of a slower fan

A

With greater number of blades

B

Of increased diameter

C

Both A & B

D

Neither A nor B

Thermal conductivity based continuous flue gas analyser makes use of varying thermal conductivity of the constituents of flue gases. Which of the following constituents of flue gases has the maximum thermal conductivity?

A

CO₂

B

N₂

C

O₂

D

CO

Heating wet steam at constant temperature is heating it at constant

A

Volume

B

Pressure

C

Entropy

D

Enthalpy

In a regenerative feed heating cycle, the optimum value of the fraction of steam extracted for feed heating

A

Decreases with increase in Rankine cycle efficiency

B

Increases with increase in Rankine cycle efficiency

C

Is unaffected by increase in Rankine cycle efficiency

D

None of the above

In resistance heating highest working temperature is obtained from heating elements made of

A

Nickel copper

B

Nichrome

C

Silicon carbide

D

Silver

Thermal shock produced by cooling is more dengerous/deleterious than that produced by heating a surface, because of the reason that

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