Technical information ABB Turbocharging Controlled information ABB Turbocharging Controlled pulse turbocharging of medium speed 5-cylinder diesel engines

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<ul><li><p>Technical information</p><p>ABB TurbochargingControlled pulse turbocharging of medium speed 5-cylinder diesel engines </p></li><li><p>2</p><p>Controlled pulse turbocharging of medium speed 5-cylinder diesel engines E. Codan a,1, I. Vlaskosa, N. Kyrtatos b,2, N. Alexandrakisb</p><p>AbstractThe smoke emissions of turbocharged marine engines can besubstantial under severe transient load-change conditions.This is already causing problems in certain port areas, and itis to be expected that visible smoke will not be tolerated in anumber of coastal regions in the near future. The EU projectSMOKERMEN was therefore set up to study the application oftwo measures for reducing smoke emissions: controlled pulseturbocharging and air injection into the turbochargers com-pressor.</p><p>This paper reports on the design of the two systems that weredeveloped and on the first engine test results, as well as onthe investigated systems potential for reducing smoke emis-sions. The combined effect of the two measures, as well asthe final configuration of the control system, will be studied inthe end phases of the project.</p><p>Key Words: Smoke emissions; pulse turbocharging; jet assist;control system</p><p>Contents</p><p>1 Introduction 3</p><p>2 Test engine 4</p><p>3 Controlled pulse turbocharging 6</p><p>4 Jet assist operation 9</p><p>5 Engine measurements 10</p><p>6 Combination of measures 13</p><p>7 Summary 14</p><p>Bibliography 15</p><p>a ABB Turbo Systems AG, Bruggerstrasse 71a, CH-5401 Baden, Switzerlandb National Technical University of Athens Laboratory of Marine Engineering</p><p>P.O. Box 64033, 157 10 Zografos, Athens Greece1 E-mail: ennio.codan@ch.abb.com, www.abb.com/turbocharging2 E-mail: nkyrt@naval.ntua.gr, www.lme.naval.ntua.gr</p><p>Translation of the paper:Die Aufladung eines mittelschnelllaufenden 5-Zylinder Dieselmotors mit geregelter Stossaufladung. (10th Turbocharging Conference, Dresden, 22 23 September 2005)</p></li><li><p>3</p><p>The development goal of higher power densities for modernlarge diesel engines remains a permanent challenge for theturbocharging system. One possibility to increase the meanpiston speed has so far found little application. Increasingmean pressures and therefore increasing turbocharging pres-sure ratios have therefore still to be confronted.</p><p>At the same time, the Miller process has proved successful asa means of improving engine efficiency while simultaneouslyreducing NOx emissions. An effective Miller process requireseven higher turbocharging pressures, however, with the resultthat single stage turbocharging is pushed to its maximum limits. Two stage turbocharging, which has often been consid-ered as an alternative in the past, has never met with as muchinterest as it does today. </p><p>This development can result in the diesel engine receiving toolittle air from the turbocharging system in both steady-stateand transient part load operation a situation associated withhigher thermal loading and severe smoke emissions. </p><p>It is known that pulse turbocharging, which was patented 80 years ago by A. Bchi (Swiss patent 122664, 1925), canmake a contribution towards improving the problem outlinedabove. The high pressure amplitudes which occur in small volume pipe systems at high turbine mean expansion ratioslead, however, to high dynamic loading of the turbine blades inthe upper power range and unacceptable losses in efficiency.One possibility for extending the application limits of pulse turbocharging is controlled pulse turbocharging [4].</p><p>A further possibility for improving the transient behavior of theturbocharged diesel engine is the injection of compressed airat the compressor wheel of the turbocharger [5].</p><p>The potential of both measures, together with a suitable control strategy, was investigated experimentally in theresearch project SMOKERMEN (SMOKe Emissions Reductionin Marine ENgines). SMOKERMEN is an EU project within the scope of the 5th Framework Programme, and is scheduledto last 42 months. The project partners are: Greek CIMAC Association ABB Turbo Systems AG Woodward Governor Nederland B.V. National Technical University of Athens Laboratory of</p><p>Marine Engineering Germanischer Lloyd AG</p><p>The project is to end this year (2005). Its current status isreported in the following.</p><p>1 Introduction</p></li><li><p>4</p><p>2 Test engine</p><p>The basic data of the test engine in the Laboratory of MarineEngineering at the National Technical University of Athens canbe seen in Table 1.</p><p>Table 1: Main data of 5L16/24 NTUA test bed engine</p><p>Configuration In-line</p><p>Number of cylinders 5</p><p>Power output 500 kW </p><p>Rotational speed 1200 rpm</p><p>Bore 160 mm</p><p>Stroke 240 mm</p><p>Compression ratio 15.5 :1</p><p>Maximum combustion pressure 180 bar</p><p>Mean effective pressure 20.7 bar</p><p>Mean piston speed 9.6 m/s</p><p>Turbocharging System Constant pressure</p><p>Turbocharger ABB TPS 48-EX</p><p>The engine is connected to a 4-quadrant electric brake fromAEG, allowing any desired transient load profiles to be pro-grammed. In its original state, the engine was fitted with aconstant pressure turbocharger combined with jet assist forload acceptance as well as with a conventional controller. </p><p>The reference status of the engine is defined by the fitting ofthe following components. A TPS 48-EX from ABB was used as turbocharger (Fig. 1),</p><p>with the turbine end arranged as standard and with a prototype compressor stage adapted for the engine.</p><p> The engines mechanical governor was replaced by a highlyefficient ATLAS electronic controller from the Woodwardcompany. This controller can be coupled as required to aconventional UG8 actuator (mechanical-hydraulic) or to anall-electronic Pro-Act actuator. </p><p>4.0</p><p>4.4</p><p>4.8</p><p>5.2</p><p>c [-]</p><p>V298 [m3/s]1.2 2.0 2.8 3.6 4.4</p><p>Com</p><p>pre</p><p>ssor</p><p> pre</p><p>ssur</p><p>e ra</p><p>tio </p><p>Volume flow</p><p>F31</p><p>F32</p><p>F33</p><p>TPS</p><p>48-</p><p>TPS</p><p>52-</p><p>TPS</p><p>57-</p><p>TPS</p><p>61-</p><p>TPS . .-E</p><p>TPS . .-D</p><p>Fig. 1a: Operating range of TPS. . -D/E/F [1, 2]. Fig. 1b: Cross sectional view of TPS. . -F [2].</p></li><li><p>5</p><p>The measuring method was adapted to the requirements ofthe project. The AVL INDISET system is used to record andevaluate the data. A torque measuring system from the Manner company permits periodic recording of the enginetorque.</p><p>Germanischer Lloyd is responsible for measuring the emis-sions. The following components were measured: NOx, HC,CO, opacity in transient engine operation, and additionally theparticle emissions in quasi-steady-state operation.</p><p>The main engine power and emissions were measured onthree different ships (Fig. 2) in order to characterize typical collective loadings and emission spectra for marine engines.Operation of the auxiliary generators was also included in themeasurements on two of the ships. Representative operatingconditions were defined on the basis of these measurements(Fig. 3), which were later tested on the test bed.</p><p>Power</p><p>NOx D</p><p>CO D</p><p>Opacity</p><p>HC W</p><p>0</p><p>10000</p><p>20000</p><p>30000</p><p>40000</p><p>0</p><p>1.0</p><p>2.0</p><p>3.0</p><p>4.0</p><p>10:01 10:59 11:57 12:54 13:52 14:49 15:47</p><p>Pow</p><p>er [k</p><p>W], </p><p>NO</p><p>x [p</p><p>pm</p><p>/10]</p><p>, H</p><p>C [p</p><p>pm</p><p>]</p><p>Op</p><p>acity</p><p> [%]; </p><p>CO</p><p> [pp</p><p>m*1</p><p>00]</p><p>Time</p><p>Fig. 3: Example of dynamic measurement on a container ship.</p><p>Fig. 2: Ships for the load profiles and emission measurements by GL.</p><p>CMV Tokyo Express, main engine, 2002-12-27 2003-12-28</p></li><li><p>6</p><p>3 Controlled pulse turbocharging</p><p>Modifications to the pipe system and turbine stage are neces-sary to provide controlled pulse turbocharging of the engine.These are described below. </p><p>3.1 Exhaust gas pipe systemBefore describing the detailed layout of the pulse pipe system,it is useful to provide a brief survey of the basic principles ofpulse turbocharging. </p><p>Pulse turbocharging in scavenged engines requires cylindergroups in which the individual cylinders do not mutually interfere during scavenging. It is known from experience thatdisturbances may not be expected if the firing interval between two cylinders in the same group satisfies the follow-ing conditions: 120 KW or 240 KW</p><p>3-pulse turbocharging satisfies the conditions and providesthe best compromise between pulse effect at part load andacceptable loss of efficiency at high engine power. </p><p>Groups of four cylinders are highly problematic for pulse turbocharging, with the result that various types of pulseconverter have been developed. 2-pulse turbocharging satis-fies the conditions described above and has a very goodpulse effect at part load. The highly irregular turbine admissionleads to a relatively high loss of efficiency in the upper loadrange. </p><p>Large engines rarely have 5 cylinders, one reason being thatthe turbocharging is problematic. The firing interval 144 CAdoes not satisfy the above conditions. An undivided systemcan be considered as a weakened form of 5 pulse turbo -charging. The division 2 3 is not possible unless specialmeasures are taken. The only alternative to a constant pres-sure system is then the 221 division. This is comparable toa 2-pulse-turbocharger. The irregularity is increased by themissing cylinder and high efficiency losses in the upper loadrange can be expected. </p><p>The system is also not symmetrical and therefore the questionis often raised as to whether the turbine stage must be dividedevenly. The answer, in practice, is yes, since the pulses enterthe turbine in succession and not simultaneously. Therefore,every exhaust gas path should be dimensioned for one pulse,regardless of how many pulses there are in one cycle.</p><p>It can be seen from the above that designing a pulse pipesystem for a 5-cylinder engine is particularly difficult. Thiscase represents a major challenge when considering theapplication of controlled pulse turbocharging, which has beenfully described for 2 and 3 pulses [4].</p><p>CYL3</p><p>CB 1</p><p>JCT 1PE 1 JCT 2 JCT 3 JCT 4 JCT 5</p><p>CB 2</p><p>CB 3COM 1</p><p>TUR1</p><p>CYL4</p><p>CYL5</p><p>CYL2</p><p>CYL1</p><p>Pipe 1</p><p>Pipe 11 Pipe 10 Pipe 9 Pipe 8 Pipe 7 Pipe 6</p><p>Pipe 2 Pipe 3 Pipe 4 Pipe 5</p><p>CYL3</p><p>CB 1</p><p>JCT 1</p><p>JCT 6 BL 1</p><p>BL 2 JCT 2</p><p>JCT 3</p><p>JCT 4</p><p>JCT 5</p><p>CB 2</p><p>CB 3COM 1</p><p>TUR 1</p><p>CYL4</p><p>CYL5</p><p>CYL2</p><p>CYL1</p><p>Pipe 1</p><p>Pipe 12Pipe 13</p><p>Pipe 14</p><p>Pipe 15</p><p>Pipe 11</p><p>Pipe 10 Pipe 9</p><p>Pipe 8Pipe 7</p><p>Pipe 6</p><p>Pipe 2 Pipe 3 Pipe 4 Pipe 5</p><p>Fig. 4: Original and optimized topology.</p></li><li><p>7</p><p>Fig. 6: Test engine with controlled pulse turbocharging.</p><p>The topology of the engine with controlled pulse turbocharg-ing (CPT) and with constant pressure turbocharging is shownin Fig. 4. It is seen that the two 2-pulse pipes are connected to the third pipe by valves. The valves are closed in the partload range for optimum utilization of the pulse energy and areopened in the upper load range, so that the pressure fluctua-tions are reduced, which significantly improves the turbineefficiency. </p><p>Fig. 5 shows the curves of fuel consumption and combustionair ratio v for various exhaust pipe diameters for the twoengine load points 100 % (left) and 40 % (right) on the pro-peller curve. Also shown are the values for the reference configuration of an undivided pipe system (horizontal greenlines), those for a conventional layout of the pulse pipes(diameter 70 mm) and for the dimensions chosen for the pipes of the controlled pulse turbocharging system (diameter60 mm), in each case marked by circles. </p><p>The conventional layout with fixed geometry would lead to a 20 % improvement in air ratio at part load and a 40 % worsening of the fuel consumption at full load compared withthe reference (SPS).</p><p>The air ratio can be increased by 30 % with the controlledsolution with closed valves at part load. With open valves atfull load the additional consumption is less than 1 %. It shouldbe pointed out that the reference configuration would not besuitable for propeller operation with heavy oil: v would haveto be increased from 1.7 to around 1.9 with the aid of a wastegate and with a new layout of the turbocharging system. Inthis case the fuel consumption at full load with the waste gateopen would be higher than with the controlled pulse system. </p><p>After the system layout had been determined, the next stepwas to define the details. The choice of the cylinder whichremains in 1-pulse operation, the arrangement of the pipeconnections and the position of the valves (Glo Tech fromWoodward) were all optimized. The targets here were: Optimum cylinder filling Minimum gas exchange losses Same scavenging conditions for all cylinders, for as long as</p><p>possible</p><p>The power system was subsequently manufactured by WTZ inRosslau and mounted on the engine (Fig. 6). The design ofthe pipe system aimed at simplicity and accessibility fordemonstrations. In the event of series production it would benecessary to rework the packaging and insulation. Also con-ceivable would be the use of a special 3-way valve instead ofthe two butterfly valves. </p><p>1.5</p><p>220</p><p>bsfc [g/kWh]</p><p>100 %</p><p>210</p><p>200</p><p>2.0</p><p>2.5</p><p>v</p><p>50 60 70</p><p>+4%</p><p>+1%</p><p>80 [mm]</p><p>Dpipe</p><p>1.5</p><p>220</p><p>bsfc [g /kWh]</p><p>40 %</p><p>VCL = Valves closed VO = Valves open SPS = Single pipe exhaust system</p><p>210</p><p>200</p><p>2.0</p><p>2.5</p><p>v</p><p>50 60 70</p><p>+30 %</p><p>+20 %</p><p>80 [mm]</p><p>Dpipe</p><p>Fig. 5: Influence of the exhaust pipe diameter.</p><p>Control valves</p></li><li><p>8</p><p>3.2 TurbineThe TPS series turbine is suitable for pulse turbocharging sothe impeller could be used for the application without anyproblems. The casing with three gas inlets, however, was notavailable as a series component for the TPS 48 and thereforehad to be specially developed (Fig. 7).</p><p>The concept of peripheral division was taken over from theTPS, i. e. each gas inlet duct consists of a spiral casing thatdirects the gas to a 120 sector of the turbine stage. This permits a relatively simple construction, good separation ofthe pulses between the sectors of the turbine stage, and onlya moderate increase in frictional losses in the casings at fulladmission. The alternative concept with a 3-channel 360 casing is not considered for the TPS. The pulse effect wouldthen be more comparable with a pulse converter solution. In addition, the design of a casing of this kind would be moreexpensive and the efficiency with full admission would beworse owing to the increased wall friction. </p><p>During engine operation, every turbine inlet producesunsteady pressure curves with phase differences. Engine</p><p>operation is simulated using both the steady-state turbinecharacteristic and the instantaneous status in each segment (quasi-steady-state treatment of the turbine). Thiscorresponds to a division of the turbines into three independ-ent turbine stages which have only the outlet pressure andspeed in common. The accuracy of this treatment is suffi-cient for an initial performance calculation (the curves in Fig. 5were calculated using this method). For greater accuracy,however, sec...</p></li></ul>

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