MEAN PISTON SPEED AFFECTING FUEL CONSUMPTION

-
MEAN PISTON SPEED:-
          It is the average speed of the piston in a reciprocating engine.
 MPS  = 2LN/ 60
 For constant stroke length
 MPS          is proportional to               N ............................(1)
Now,
    Power = PLAN/ 60
For constant L and A
    Power     is proportional to            PN .............................(2)
                                                                             2/3                      3
 But, Power    is proportional to       (displacement)        (Speed)
For constant displacement,
                                                                  3
  Power        is proportional to         (speed)  ........................(3)
 But speed,
   V        is proportional to             Pitch * N,      So for constant pitch,
    V       is proportional to              N ...................................(4)

From (1), (2), (3) and (4)
                                                           3
    Power    is proportional to    ( MPS)   ....................................(5)
Now, Fuel consumed / unit time   is proportional to     Power ................................(6)

From (5) and (6)
                                                                               3
  Fuel consumed/ unit time   is proportional to (MPS)

MPS LIMITATION:-

  1. Increase in MPS will increase the dynamic forces and moments and this will affect bearings, bearing bolts etc.
  2. If MPS is high time available for fuel consumption is less.
  3. If  MPS is low, compression will be isothermal but we want compression to be adiabatic. Low MPS will cause compression temperature to be low resulting in incomplete combustion and increase in fuel consumption.
  4. Speed decreases service life of frictional parts.
MPS play an important role in exchange of gases. Beyond a certain piston speed the efficiency of the gas exchange process drops sharply there by resulting in poor combustion.

ASCERTAINING OPTIMUM USE OF FUEL OIL:-
1) Factors affecting scavenging to be maintained.
  • Scavenge ports to be kept clean.
  • turbo charger air filter to be kept clean.
  • Air cooler both air and water side clean
  • exhaust valve maintenance as per PMS
2) Engine parameters must be closely monitored.
  • Exhaust temperature and colour of smoke.
  • Engine peak pressure and performance.
  • Inspection through scavenge ports.
  • Scavenge temperature.

Comments

Post a Comment

Popular posts from this blog

CRITICAL EQUIPMENT AND OPERATION UNDER ISM CODE.

-
Critical equipments are equipments whose failure will lead to a potential hazardous situation or an accident, thereby causing injury to personnel or loss of life or damage to marine environment or property. This causes deviation or failure of the ISM objective 1.2.2 of ISM code. PROVISION IN ISM :- Element 10.3 of ISM code states----      The company should establish procedures in its safety management system to identify equipment and technical system, the sudden operational failure of which may result in hazardous situation. The SMS should provide for specific measures aimed at promoting the reliability of such equipment or systems. These measures should include the regular testing of standby arrangement or equipment or technical systems that are not in continuous use.      Hence SMS must have with respect to the critical equipment have procedures:- 1) To identify them 2) To ensure their test and functional reliability 3) To establish and use the alternative arrangements on
Read more

Various codes of PSC inspection and how to present to PSCO in case IOPP equipment is not working

-
Following are the various codes which are used to represent Action to be taken by vessel against the deficiency reported:- Deficiency Action Codes 10 deficiency rectified 15 rectify deficiency at next port 16 rectify deficiency within 14 days 17 rectify deficiency before departure 18 rectify deficiency within 3 months  30 detainable deficiency 99 other (specify) Note: For ISM deficiencies, only code 10, 18 and 30 can be used. Restrictions on Updating Codes Both codes 15 and 16 can only be updated to code 10. Code 17 can only be updated to code 10, 15, 16 and 99. Code 18 can only be updated to code 10. Code 30 can only be updated to: - code 10 or 18 (ISM def.) - code 10 or 99 (non - ISM def.) Code 18 can only be updated to code 10. We will discuss one case where 15 ppm equipment has started malfunctioning just before the arrival of the port. After investigating it was found that the  coalescer filter has become very dirty and because of this th
Read more

CLEAR GROUND FOR DETAILED INSPECTION DURING PSC INSPECTION

-
CLEAR GROUNDS:- Evidence that the ship, its equipment or its crew does not correspond substantially with requirement of relevant convention or that the master or crew members are not familiar with essential shipboard procedures relating to the safety of ship or prevention of pollution.     Clear grounds to conduct a more detailed inspection include:- 1) The absence of principal equipment or arrangements required by convention :- e.g. MARPOL annex 1 requires that ship above 400 GRT and above must have an OWS with automatically stopping device, if effluent exceeds 15 ppm. Absence of this principal equipment will lead to detention. 2) Evidence from a review of the ship's certificate that it is clearly invalid: - e.g. Safety equipment certificate found invalid since no renewal survey was carried out. 3) Evidence that the ship's logs, manuals or other required documentation are not on board, are not maintained or falsely maintained:- e.g. ORB part 1 not present on board or in
Read more