xviIntroduction:ACenturyofDieselProgressFIGUREI.7AB&W840-Dfour-strokedouble-acting engine powered SwedishAmericaLine'sGripsholmin1925GOODBYETOBLASTINJECTIONIt was towards the end of the1920s that most designers concluded that theblast air-fuel injection diesel engine-with its need for large, often trouble-someand energy-consuminghigh-pressurecompressors-should bedisplacedby the airless (or compressor-less) type.Air-blastfuel injection called forcompressed airfromapressure bottletoentrain the fuel and introduce it in a finely atomized state via a valve needle intothe combustion chamber. The air-blast pressure, which was only just slightlyabove the ignition pressure in the cylinder, was produced by a water-cooled compressor driven off the engine connecting rod by means of a rocking lever
xvi Introduction: A Century of Diesel Progress Goodbye to blast injection It was towards the end of the 1920s that most designers concluded that the blast air–fuel injection diesel engine—with its need for large, often troublesome and energy-consuming high-pressure compressors—should be displaced by the airless (or compressor-less) type. Air-blast fuel injection called for compressed air from a pressure bottle to entrain the fuel and introduce it in a finely atomized state via a valve needle into the combustion chamber. The air-blast pressure, which was only just slightly above the ignition pressure in the cylinder, was produced by a water-cooled compressor driven off the engine connecting rod by means of a rocking lever. Figure I.7 A B&W 840-D four-stroke double-acting engine powered Swedish America Line’s Gripsholm in 1925
GoodbyetoblastinjectionxviFIGUREI.8Sulzer's1S100single-cylinderexperimentaltwo-strokeengine(1912)featureda1000mmboreRudolf Dieselhimselfwasneverquite satisfied withthis concept (whichhe called self-blast injection)since it was complicated and hence susceptible tofailure-andalsobecausethe‘airpump'tappedasmuchas15percentoftheengineoutput.Diesel hadfiledapatentasearlyas1905coveringaconceptforthesolidinjection of fuel, with a delivery pressure of several hundred atmospheres. Akey feature was the conjoining of pump and nozzle and their shared accommo-dation in the cylinder head.One reason advanced for the lack of follow-up wasthatfew of the manyengine licensees showed any interest
Rudolf Diesel himself was never quite satisfied with this concept (which he called self-blast injection) since it was complicated and hence susceptible to failure—and also because the ‘air pump’ tapped as much as 15 per cent of the engine output. Diesel had filed a patent as early as 1905 covering a concept for the solid injection of fuel, with a delivery pressure of several hundred atmospheres. A key feature was the conjoining of pump and nozzle and their shared accommodation in the cylinder head. One reason advanced for the lack of follow-up was that few of the many engine licensees showed any interest. Goodbye to blast injection xvii Figure I.8 Sulzer’s 1S100 single-cylinder experimental two-stroke engine (1912) featured a 1000mm bore
xviliIntroduction:ACenturyofDieselProgressArenewed thrust came in 1910 whenVickers'technical directorMcKechnie(independently of Diesel, and six months after a similar patent from Deutz inGermany)proposed in anEnglishpatentan'accumulator systemforairless directfuel injection'at pressures between 140bar and 420bar.By 1915he had devel-oped andtested an'operational'diesel engine withdirect injection,and is thusregarded as the main inventor of high-intensity direct fuel injection. Eight yearslaterithad becomepossibletomanufacturereliableproductioninjectionpumpsfor high pressures, considerably expanding the range of applications (Figure L.9).The required replacement fuel injection technology thus had its roots in thepioneering days (a Doxford experimental engine was converted to airless fuelFIGUREI.9AB&W662-WF/40two-strokedouble-actingengine,firstinstalledasasix-cylindermodelintheAmerika(1929)
xviii Introduction: A Century of Diesel Progress A renewed thrust came in 1910 when Vickers’ technical director McKechnie (independently of Diesel, and six months after a similar patent from Deutz in Germany) proposed in an English patent an ‘accumulator system for airless direct fuel injection’ at pressures between 140bar and 420bar. By 1915 he had developed and tested an ‘operational’ diesel engine with direct injection, and is thus regarded as the main inventor of high-intensity direct fuel injection. Eight years later it had become possible to manufacture reliable production injection pumps for high pressures, considerably expanding the range of applications (Figure I.9). The required replacement fuel injection technology thus had its roots in the pioneering days (a Doxford experimental engine was converted to airless fuel Figure I.9 A B&W 662-WF/40 two-stroke double-acting engine, first installed as a six-cylinder model in the Amerika (1929)
Heavyfuel oilsxixinjection in 1911) but suitable materials and manufacturing techniques had tobe evolved for the highly stressed camshaft drives and pump and injector com-ponents.The refinement of direct fuel injection systems was also significantfor the development of smaller high-speed diesel engines.ABOOSTFROMTURBOCHARGINGA major boost to engine output and reductions in size and weight resultedfrom the adoption of turbochargers. Pressure charging by various methods wasapplied by most enginebuilders in the 1920s and 1930s to ensure an adequatescavenge air supply: crankshaft-driven reciprocating air pumps, side-mountedpumps driven by levers off the crossheads, attached Roots-type blowers orindependently driven pumps and blowers. The pumping effect from the pistonunderside was also used for pressure charging in some designs.The Swiss engineer Alfred Bichi, considered the inventor of exhaust gasturbocharging, was granted a patent in 1905 and undertook his initial turbo-charging experiments at Sulzer Brothers in 1911/1915.It was almost 50 yearsafterthat first patent, however,before the principle could be applied satisfactor-ily to large marine two-stroke engines.The first turbocharged marine engines were 10-cylinder Vulcan-MAN four-stroke single-acting models in the twin-screw Preussen and Hansestadt Danzig,commissioned in 1927. Turbocharging under a constant pressure system byBrownBoveriturboblowersincreased theoutputof these540mmbore/600mmstrokeenginesfrom1250kWat240rev/minto1765kWcontinuouslyat275rev/min,withamaximum of 2960kW at317rev/min.Bichiturbocharging waskeenly exploited by large four-stroke engine designers, and in 1929 some 79engines totalling 162000kW were in service or contracted with the systemIn 1950/1951 MAN was the forerunner in testing and introducing high-pressure turbocharging for medium-speed four-stroke engines for which boostpressures of 2.3barweredemanded and attained.Progressive advances in the efficiency of turbochargers and systems deve-lopment made it possible by the mid-1950s for the major two-stroke engine-builders to introduce turbocharged designs.Amorerecentcontributionof turbochargers,withoverall efficienciesnowtopping 70 per cent, is to allow some exhaust gas to be diverted to a powerrecovery turbine and supplement the main engine effort or drive a generator.A range of modern power gas turbines is available to enhance the competitive-ness of two-stroke and larger four-stroke engines, yielding reductions in fuelconsumption or increased power.HEAVYFUELOILSAnother important step in strengthening the status of the diesel engine inmarine propulsion was R&D enabling it to burn cheaper, heavier fuel oils.Progress was spurred in the mid-1950s by the availability of cylinder lubricantsabletoneutralizeacid combustionproductsand hencereducewearratesto
injection in 1911) but suitable materials and manufacturing techniques had to be evolved for the highly stressed camshaft drives and pump and injector components. The refinement of direct fuel injection systems was also significant for the development of smaller high-speed diesel engines. A boost from turbocharging A major boost to engine output and reductions in size and weight resulted from the adoption of turbochargers. Pressure charging by various methods was applied by most enginebuilders in the 1920s and 1930s to ensure an adequate scavenge air supply: crankshaft-driven reciprocating air pumps, side-mounted pumps driven by levers off the crossheads, attached Roots-type blowers or independently driven pumps and blowers. The pumping effect from the piston underside was also used for pressure charging in some designs. The Swiss engineer Alfred Büchi, considered the inventor of exhaust gas turbocharging, was granted a patent in 1905 and undertook his initial turbocharging experiments at Sulzer Brothers in 1911/1915. It was almost 50 years after that first patent, however, before the principle could be applied satisfactorily to large marine two-stroke engines. The first turbocharged marine engines were 10-cylinder Vulcan-MAN fourstroke single-acting models in the twin-screw Preussen and Hansestadt Danzig, commissioned in 1927. Turbocharging under a constant pressure system by Brown Boveri turboblowers increased the output of these 540mm bore/600mm stroke engines from 1250kW at 240rev/min to 1765kW continuously at 275rev/ min, with a maximum of 2960kW at 317rev/min. Büchi turbocharging was keenly exploited by large four-stroke engine designers, and in 1929 some 79 engines totalling 162000kW were in service or contracted with the system. In 1950/1951 MAN was the forerunner in testing and introducing highpressure turbocharging for medium-speed four-stroke engines for which boost pressures of 2.3 bar were demanded and attained. Progressive advances in the efficiency of turbochargers and systems development made it possible by the mid-1950s for the major two-stroke enginebuilders to introduce turbocharged designs. A more recent contribution of turbochargers, with overall efficiencies now topping 70 per cent, is to allow some exhaust gas to be diverted to a power recovery turbine and supplement the main engine effort or drive a generator. A range of modern power gas turbines is available to enhance the competitiveness of two-stroke and larger four-stroke engines, yielding reductions in fuel consumption or increased power. Heavy fuel oils Another important step in strengthening the status of the diesel engine in marine propulsion was R&D enabling it to burn cheaper, heavier fuel oils. Progress was spurred in the mid-1950s by the availability of cylinder lubricants able to neutralize acid combustion products and hence reduce wear rates to Heavy fuel oils xix
xxIntroduction:ACenturyofDieselProgressFIGUREI.10 Direct fuel injection system introduced by Sulzer in 1930, showing thereversing mechanism and cam-operated starting air valve.Airless fuel injection hadbeen adoptedby all manufacturers of largemarine engines by the beginning of the1930s:amajordrawbackofearlierengineswastheblastinjectionsystemand itsrequirementforlarge,high-pressureaircompressors whichdictatedconsiderablemaintenance and added to parasitic powerlosseslevels experienced with diesel oil-burning. All low-speed two-stroke and manymedium-speed four-stroke engines are now released for operation on low-gradefuelsofupto700cSt/50°Cviscosity,anddevelopment workis extendingthecapability tohigher speed designsCombating the deterioration in bunker quality is just one example of howdiesel enginedevelopers-in association with lube oil technologists and fueltreatment specialists-have managed successfully to adapt designs to contem-porary market demands (Figures 1.10 and 1.11).ENVIRONMENTALPRESSURESA continuing effort to reduce exhaust gas pollutants is another challengefor enginedesignerswho facetightening international controls in the yearsahead on nitrogen oxide, sulphur oxide, carbon dioxide and particulate emis.sions.In-engine measures (e.g.retarded fuel injection) can cope with theIMO's NOx requirements while direct water injection, fuel emulsification andcharge air humidification can effect greater curbs.Selective catalytic reduc-tion (SCR)systems,however, may be dictated to meet the toughestfutureregional limits.Demands for'smokeless'engines,particularly from cruise operatorsin pollution-sensitive arenas,have been successfully addressed-commonrail fuel injection systems playing a significant role-but the development ofengines withlowerairborne sound levelsremainsachallenge
xx Introduction: A Century of Diesel Progress levels experienced with diesel oil-burning. All low-speed two-stroke and many medium-speed four-stroke engines are now released for operation on low-grade fuels of up to 700 cSt/50°C viscosity, and development work is extending the capability to higher speed designs. Combating the deterioration in bunker quality is just one example of how diesel engine developers—in association with lube oil technologists and fuel treatment specialists—have managed successfully to adapt designs to contemporary market demands (Figures I.10 and I.11). Environmental pressures A continuing effort to reduce exhaust gas pollutants is another challenge for engine designers who face tightening international controls in the years ahead on nitrogen oxide, sulphur oxide, carbon dioxide and particulate emissions. In-engine measures (e.g. retarded fuel injection) can cope with the IMO’s NOx requirements while direct water injection, fuel emulsification and charge air humidification can effect greater curbs. Selective catalytic reduction (SCR) systems, however, may be dictated to meet the toughest future regional limits. Demands for ‘smokeless’ engines, particularly from cruise operators in pollution-sensitive arenas, have been successfully addressed—common rail fuel injection systems playing a significant role—but the development of engines with lower airborne sound levels remains a challenge. Figure I.10 Direct fuel injection system introduced by Sulzer in 1930, showing the reversing mechanism and cam-operated starting air valve. Airless fuel injection had been adopted by all manufacturers of large marine engines by the beginning of the 1930s: a major drawback of earlier engines was the blast injection system and its requirement for large, high-pressure air compressors which dictated considerable maintenance and added to parasitic power losses