The theoretical mechanical efficiency of a jet engine (neglecting frictional and thermal losses), when driving a vehicle has its maximum

1.   Only when the vehicle moves at sonic velocity

2.  When outlet gases approach zero absolute velocity

3.  When the vehicle speed approaches the magnitude of the relative velocity of gases at nozzle exit

4.  Only when the relative velocity at nozzle exit is at its maximum

4

When outlet gases approach zero absolute velocity

Explanation :
No Explanation available for this question

A turbo – charged four-stroke direct injection diesel engine has a displacement volume of 0.0259 m3 (25.9 litres). The engine has an output of 950 kW at 2200 rpm. The mean effective pressure (in Mpa) is closest to

1.   2

2.  1

3.   0.2

4.  0.1

4

2

Explanation :
No Explanation available for this question

The crank radius of a single-cylinder I.C. engine is 60mm and the diameter of the cylinder is 80mm. The swept volume of the cylinder in cm3 us

1.  48

2.  96

3.  302

4.  603

4

603

Explanation :
No Explanation available for this question

If a mass of moist air in airtight vessel in heated to a higher temperature, then

1.  Specific humidity of the air increases

2.  Specific humidity of the air decreases

3.   Relative humidity of the air increases

4.   Relative humidity of the air decreases

4

Relative humidity of the air decreases

Explanation :
No Explanation available for this question

The pressure, dry bulb temperature and relative humidity of air in a room are 1 bar, 30°C and 70%, respectively. If the saturated steam pressure at 30°C is 4.25 kPa, the specific humidity of the room air in kg water vapour/kg dry air is

1.   0.0083

2.  0.0101

3.  0.0191

4.   0.0232

4

0.0191

Explanation :
No Explanation available for this question

Wet bulb depression, under saturated ambient air conditions

1.   Is always positive

2.  Is always negative

3.  Is always zero

4.  May have a value depending upon the dew point temperature

4

Is always zero

Explanation :
No Explanation available for this question

Wet bulb depression, under saturated ambient air conditions

1.   Is always positive

2.  Is always negative

3.  Is always zero

4.  May have a value depending upon the dew point temperature

4

Is always zero

Explanation :
No Explanation available for this question

Atmospheric air from 40°C and 60 percent relative humidity can be brought to 20°C and 60 percent relative humidity by;

1.  Cooling and dehumidification process

2.  Cooling and humidification process

4.  Sensible cooling process

4

Cooling and dehumidification process

Explanation :
No Explanation available for this question

If moist air is cooled by sensible heat removal, which of the following is true

1.  Neither relative humidity nor specific humidity changes

2.  Specific humidity changes but not relative humidity

3.  Both relative humidity and specific humidity change

4.  None of the above

4

None of the above

Explanation :
No Explanation available for this question

1.  67%

2.  55%

3.  83%

4.  71%

4