Super-Long stroke
advantages
- Low quality fuel can be burnt
(since more time is available for fuel
combustion).
- Slow rpm is possible
(-->so large diameter propeller can be used -->propeller
efficiency increases.)
- More time for heat dissipation to cooling water.
-better scavenging
-higher compression ratio can be achieved.
(so more fuel can be burnt per stroke and more power
developed)
-reduced exhaust temperature
-reduced fouling, smoke, NOx
-increased thermal efficiency
(heat converted into useful work / total heat
supplied)
-power to weight ratio is more.
Classification based on
stroke/bore ratio (For Man B&W)
Short stroke : 2.6-3.2
Long stroke : 3.2-4.0
Super-Long stroke : 4.0-4.7
Ultra-Long stroke : >4.7
Can u please justify point number 2
ReplyDeleteSLS increases piston travel time,thereby reducing c/s speed , hence more time for combustion
DeleteHow exhaust temperature is reduced nd how nox, fouling and smoke is reduced... Can u plz explain
ReplyDeleteThere will be less unburnt fuel left in exhaust gas
Deletewith increase in stroke length we have an advantage of burning dirty fuel/low grade fuel at min rev/low speed with good efficiency. this will result in proper utilization of fuel resulting in reduction of nox content.also with increase in stroke length heat generated is consumed in reciprocation action of piston resulting in low exhaust temperature.
ReplyDeletewhat is the disadvantage of super long strock
ReplyDeleteThere is no disadvantage but yes there is a limitation as longer the stroke bigger will be crank throw and wider will be the width of engine room.we want as long stroke as possible but economically we settle for what is now trending ..
DeleteIncreased lateral force on guides due to relatively short connecting rods
DeleteEnter your comment..can you show some sketches
ReplyDeletePlease mention any disadvantages like difficulty in cooling or so...
ReplyDelete