Lowerspeeds,largerboresxxiFIGUREI.11Cross-sectionofSulzerSD72two-strokeengine (1943).Eachcylinderhad itsownscavengepump,leverdrivenoffthecrosshead.ThepistonswereoilcooledtoavoidtheearlierproblemofwaterleaksintothecrankcaseEnvironmentalpressuresarealso stimulatingthedevelopmentandwiderapplication of dual-fuel diesel and gas engines, which have earned break-throughs in offshore support vessel, ferry and LNG carrier propulsion.LOWERSPEEDS,LARGERBORESSpecificoutputthresholdshavebeenboostedto6950kW/cylinderbyMANDiesel's 1080mm bore MANB&W MC/ME two-stroke designs.A single14-cylinder model can thus deliver up to 97300kW for propelling the largest
Environmental pressures are also stimulating the development and wider application of dual-fuel diesel and gas engines, which have earned breakthroughs in offshore support vessel, ferry and LNG carrier propulsion. Lower speeds, larger bores Specific output thresholds have been boosted to 6950 kW/cylinder by MAN Diesel’s 1080mm bore MAN B&W MC/ME two-stroke designs. A single 14-cylinder model can thus deliver up to 97300kW for propelling the largest Lower speeds, larger bores xxi Figure I.11 Cross-section of Sulzer SD72 two-stroke engine (1943). Each cylinder had its own scavenge pump, lever driven off the crosshead. The pistons were oil cooled to avoid the earlier problem of water leaks into the crankcase
xxiiIntroduction:ACenturyofDiesel Progressprojected container ships with service speeds of 25 knots-plus. (The largestcontainer ships of the 1970s typically required twin 12-cylinder low-speedengines developing a combined 61760kW).Both MAN Diesel and WartsilaCorporation have extended their low-speed engine programmes from the tradi-tional 12-cylinder limit to embrace 14-cylinder models.Engine development has also focused on greater fuel economy achievedbyacombinationof lowerrotational speeds,highermaximum combustionpressures and more efficient turbochargers. Engine thermal efficiency hasbeen raised to over 54per cent and specific fuel consumptions can be as lowas 155g/kWh.At the same time,propeller efficiencies have been considerablyimproved due to minimum engine speeds reduced to as low as 55rev/min.The pace and expense of development in the low-speed engine sector havebeen such that only three designer/licensors remain active in the internationalmarket.The roll call of past contenders include names either long forgotten orliving on in other fields: AEG-Hesselman, Deutsche Werft, Fullagar, Krupp,McIntosh and Seymour,Neptune,Nobel,North British,Polar,RichardsonsWestgarth, Still, Tosi,Vickers, Werkspoor and Worthington.The most recentcasualties were Doxford, Gotaverken and Stork, some of whose productsremainat sea indwindlingnumbers.These pioneering designers displayed individual flair within generic classifi-cations which offered two- or four-stroke, single- or double-acting,and single- oropposed-piston arrangements. The Still concept even combined the Diesel prin-ciple with a steam engine: heat in the exhaust gases and cooling water was usedto raise steam which was then supplied to the underside of the working piston.Evolution has decreed that the surviving trio of low-speed engine design-ers (MAN Diesel, Mitsubishi and Sulzer) should all settle-for the present atleast-on a common basic philosophy:uniflow-scavenged,single hydraulicallyactuated exhaust valve in the head, constant pressure turbocharged, two-strokecrosshead engines exploiting increasingly high stroke/bore ratios (up to 4.4:1)and low operating speeds for direct coupling to the propeller (Figures IL.12 andI.13).Bore sizes range from260mm to1080mm (FigureI.14).In contrast the high-/medium-speed engine market is served by numerouscompanies offering portfolios embracing four-stroke,trunk piston, uniflow-orloop-scavenged designs, and rotating piston types, with bore sizes up to 640 mm.Wartsila's 64 engine-the most powerful medium-speed design-offers a ratingofover2000kW/cylinderfrom the in-linemodels (FiguresL15and 1.16)Recent years have seen the development of advanced medium-and high-speed designs with high power-to-weight ratios and compact configurations upto V20 cylinders forfast commercial vessel and warshippropulsion.THEFUTUREIt is difficult to envisage the diesel engine being seriously troubled by alterna-tive prime movers in the short-to-medium term but any regulation- or market-driven shift to much cleaner fuels (liquid or gas) could open the door to
xxii Introduction: A Century of Diesel Progress projected container ships with service speeds of 25 knots-plus. (The largest container ships of the 1970s typically required twin 12-cylinder low-speed engines developing a combined 61 760kW). Both MAN Diesel and Wärtsilä Corporation have extended their low-speed engine programmes from the traditional 12-cylinder limit to embrace 14-cylinder models. Engine development has also focused on greater fuel economy achieved by a combination of lower rotational speeds, higher maximum combustion pressures and more efficient turbochargers. Engine thermal efficiency has been raised to over 54 per cent and specific fuel consumptions can be as low as 155g/kWh. At the same time, propeller efficiencies have been considerably improved due to minimum engine speeds reduced to as low as 55rev/min. The pace and expense of development in the low-speed engine sector have been such that only three designer/licensors remain active in the international market. The roll call of past contenders include names either long forgotten or living on in other fields: AEG-Hesselman, Deutsche Werft, Fullagar, Krupp, McIntosh and Seymour, Neptune, Nobel, North British, Polar, Richardsons Westgarth, Still, Tosi, Vickers, Werkspoor and Worthington. The most recent casualties were Doxford, Götaverken and Stork, some of whose products remain at sea in dwindling numbers. These pioneering designers displayed individual flair within generic classifications which offered two- or four-stroke, single- or double-acting, and single- or opposed-piston arrangements. The Still concept even combined the Diesel principle with a steam engine: heat in the exhaust gases and cooling water was used to raise steam which was then supplied to the underside of the working piston. Evolution has decreed that the surviving trio of low-speed engine designers (MAN Diesel, Mitsubishi and Sulzer) should all settle—for the present at least—on a common basic philosophy: uniflow-scavenged, single hydraulically actuated exhaust valve in the head, constant pressure turbocharged, two-stroke crosshead engines exploiting increasingly high stroke/bore ratios (up to 4.4:1) and low operating speeds for direct coupling to the propeller (Figures I.12 and I.13). Bore sizes range from 260mm to 1080mm (Figure I.14). In contrast the high-/medium-speed engine market is served by numerous companies offering portfolios embracing four-stroke, trunk piston, uniflow- or loop-scavenged designs, and rotating piston types, with bore sizes up to 640mm. Wärtsilä’s 64 engine—the most powerful medium-speed design—offers a rating of over 2000kW/cylinder from the in-line models (Figures I.15 and I.16). Recent years have seen the development of advanced medium- and highspeed designs with high power-to-weight ratios and compact configurations up to V20 cylinders for fast commercial vessel and warship propulsion. The future It is difficult to envisage the diesel engine being seriously troubled by alternative prime movers in the short-to-medium term but any regulation- or marketdriven shift to much cleaner fuels (liquid or gas) could open the door to
884WS-15050VF9074VTF14084-VT2BF180K80GFThefutureOAbt.19301940195019601970FIGUREI.12DevelopmentofBurmeister&Wainuniflow-scavengedenginedesignsxxili
The future xxiii 884WS–150 50VF–90 74VTF–140 84–VT2BF–180 K80GF Abt. 1930 1940 1950 1960 1970 Figure I.12 Development of Burmeister & Wain uniflow-scavenged engine designs
xxivIntroduction:ACenturyofDieselProgressg/BHPh4158154.7154150.6150146142139.5139.5138136134134.5130131128126125122LGFK-GFL-GFCL-GFCAL-GBE1973197619781979/801982/83ImpulseTurbocharged-ConstantPressureTurbochargedFIGUREI.13AdvancesinspecificfuelconsumptionbyBurmeister&Wainuniflowscavengedtwo-strokeenginedesigns(9o0mmboremodels)FIGUREI.14Burmeister&Wainuniflow-scavengingsystem
xxiv Introduction: A Century of Diesel Progress 158 154 150 146 142 138 134 130 126 122 g/BHPh 154.7 150.6 139.5 139.5 134.5 136 131 128 125 K–GF 1973 L–GF 1976 L–GFC 1978 L–GFCA 1979/80 L–GBE 1982/83 Impulse Turbocharged Constant Pressure Turbocharged Figure I.13 Advances in specific fuel consumption by Burmeister & Wain uniflowscavenged two-stroke engine designs (900mm bore models) Figure I.14 Burmeister & Wain uniflow-scavenging system
ThefutureXXVFIGUREI.15 Cross-sectionofa modern large-boretwo-strokelow-speedengine,theWartsilaRTA96Cthwarted rivals, such as gas engines and gas turbines.Fuel cells will seek ashipboard foothold, initially in low auxiliary power applications.As well as stifling coal- and oil-fired steam plant in its rise to dominance incommercialpropulsion,thedieselengineshrugged off challengesfromnuclear(steam) propulsion and gas turbines. Both modes found favour in warships,however,and aero-derived gas turbines carved niches in fast ferry and cruisetonnage. A sustained challenge from gas turbines has been undermined byfuel pricerises (although combined diesel and gas turbinesolutionsremain anoption for high-powered installations) and diminishing fossil fuel availabilitymayyetsee nuclearpropulsion revived inthe longerterm
thwarted rivals, such as gas engines and gas turbines. Fuel cells will seek a shipboard foothold, initially in low auxiliary power applications. As well as stifling coal- and oil-fired steam plant in its rise to dominance in commercial propulsion, the diesel engine shrugged off challenges from nuclear (steam) propulsion and gas turbines. Both modes found favour in warships, however, and aero-derived gas turbines carved niches in fast ferry and cruise tonnage. A sustained challenge from gas turbines has been undermined by fuel price rises (although combined diesel and gas turbine solutions remain an option for high-powered installations) and diminishing fossil fuel availability may yet see nuclear propulsion revived in the longer term. The future xxv Figure I.15 Cross-section of a modern large-bore two-stroke low-speed engine, the Wärtsilä RTA96C