Automatic optimization of marine diesel engine performance using loop control of the cylinder pressure process has been under development for a number of years at both MAN Diesel & Turbo and Wärtsilä. Targeting the slow speed two stroke engines, the key to successful implementation of automatic loop control is reliable sensors able to accurately measure cylinder pressure, providing key data to evaluate the fuel efficiency and engine conditions. For every one bar increase in average maximum cylinder firing pressure there is a corresponding decrease of between 0.20 to 0.25 g/kWh in specific fuel consumption

The problem is that without automatic loop control, ship engines are tuned manually to operate within safe limits while leaving a safety margin for variations in fuel properties and operating conditions. Less than 15 per cent of new delivered ships have online cylinder pressure monitoring equipment. According to observations of MAN Diesel & Turbo, engines are poorly balanced between cylinders and are often outside recommended deviation limits. They are also operating with a low maximum cylinder pressure level. The combined  result is an increase in fuel consumption and higher CO2 emissions.

The benefit of auto tuning is that the cylinder pressures are balance and at the highest acceptable pressure offering a potential fuel consumption reduction up to 3 g/kWh with an average of 1 g/kWh and emission potential of 2 per cent CO2 reduction. Additional advantages are  reduced maintenance costs, increased reliability and ease of  workload on the crew.

MAN Diesel & Turbo, ABB, and A.P.Moller have together been running loop control projects since autumn 2007. Under the Danish industry’s Green Ship of the Future project, MAN Diesel & Turbo and A.P.Moller have been field testing an auto tuning system on the MAN B&W 6S60ME-C propulsion engine of the MV Maersk Wizard (present name MV Höegh Kobe) vehicle carrier since early 2008 and the tests continue.