The air flow through a four-cylinder, four-stroke gasoline engine was measured by means of a 7.5-cm diameter accurate flow-measuring device with its discharge coefficient of 0.66. During a Power Plants laboratory trial on this engine the following data were noted down as follows: Bore (d) = 110 mm Stroke (Ls) = 12 cm Shaft speed (Ns) = 180000 rev/h Mass flow rate of fuel used (m& f ) = 166.67 g/min Brake power (W&b ) = 40 kW Higher calorific value (HCVf) = 44 MJ/kg Heat carried away by water vapours in the exhaust (qsteam) = 2000 kJ/kg Pressure drop across the measuring device (hw), by a water manometer = 4 cmH2O Atmospheric pressure (Pa) = 1.01 bar Atmospheric temperature (ta) = 23 C Determine: the brake thermal efficiency (b, th ), the brake mean effective pressure (Pb, m ) , and the volumetric efficiency (vol, free-air cond.) based on free air conditions. For air: Ra = 0.287 kJ/(kg·K) and the mass density if water, w 987kg/m3 and the local acceleration due to gravity, g = 9.79 m/s2.
The air flow through a four-cylinder, four-stroke gasoline engine was measured by means of a 7.5-cm diameter accurate flow-measuring device with its discharge coefficient of 0.66. During a Power Plants laboratory trial on this engine the following data were noted down as follows:
|
Bore (d) |
= |
110 |
mm |
|
Stroke (Ls) |
= |
12 |
cm |
|
Shaft speed (Ns) |
= |
180000 |
rev/h |
|
Mass flow rate of fuel used (m& f ) |
= |
166.67 |
g/min |
|
Brake power (W&b ) |
= |
40 |
kW |
|
Higher calorific value (HCVf) |
= |
44 |
MJ/kg |
|
Heat carried away by water vapours in the exhaust (qsteam) |
= |
2000 |
kJ/kg |
|
Pressure drop across the measuring device (hw), by a water manometer |
= |
4 |
cmH2O |
|
Atmospheric pressure (Pa) |
= |
1.01 |
bar |
|
Atmospheric temperature (ta) |
= |
23 |
C |
Determine:
- the brake thermal efficiency (b, th ),
- the brake mean effective pressure (Pb, m ) , and
- the volumetric efficiency (vol, free-air cond.) based on free air conditions.
For air: Ra = 0.287 kJ/(kg·K) and the mass density if water, w 987kg/m3 and the local acceleration due to gravity, g = 9.79 m/s2.
NOTE: In the beginning of your Solution after Data, draw the actual P-v diagram for the engine per cycle and a simple schematic diagram of the test rig with the names of all the salient parts as well as the given property values properly labelled at appropriate locations near the parts. The marks allocated for P-v and schematic diagrams will be deducted if you do not draw these.
(Please send in two hours only three hours remaing )
Trending now
This is a popular solution!
Step by step
Solved in 4 steps with 11 images
