Technical information

ABB TurbochargingControlled pulse turbocharging of medium speed 5-cylinder diesel engines

2

Controlled pulse turbocharging of medium speed 5-cylinder diesel engines E. Codan a,1, I. Vlaskosa, N. Kyrtatos b,2, N. Alexandrakisb

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 turbocharger’s com-pressor.

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.

Key Words: Smoke emissions; pulse turbocharging; jet assist;control system

Contents

1 Introduction 3

2 Test engine 4

3 Controlled pulse turbocharging 6

4 Jet assist operation 9

5 Engine measurements 10

6 Combination of measures 13

7 Summary 14

Bibliography 15

a ABB Turbo Systems AG, Bruggerstrasse 71a, CH-5401 Baden, Switzerlandb National Technical University of Athens – Laboratory of Marine Engineering

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

Translation of the paper:Die Aufladung eines mittelschnelllaufenden 5-Zylinder Dieselmotors mit geregelter Stossaufladung. (10th Turbocharging Conference, Dresden, 22 – 23 September 2005)

3

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.

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.

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.

It is known that pulse turbocharging, which was patented 80 years ago by A. Büchi (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].

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].

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

Marine Engineering– Germanischer Lloyd AG

The project is to end this year (2005). Its current status isreported in the following.

1 Introduction

4

2 Test engine

The basic data of the test engine in the Laboratory of MarineEngineering at the National Technical University of Athens canbe seen in Table 1.

Table 1: Main data of 5L16/24 NTUA test bed engine

Configuration In-line

Number of cylinders 5

Power output 500 kW

Rotational speed 1200 rpm

Bore 160 mm

Stroke 240 mm

Compression ratio 15.5 :1

Maximum combustion pressure 180 bar

Mean effective pressure 20.7 bar

Mean piston speed 9.6 m/s

Turbocharging System Constant pressure

Turbocharger ABB TPS 48-EX

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.

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),

with the turbine end arranged as standard and with a prototype compressor stage adapted for the engine.

– The engine’s 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.

4.0

4.4

4.8

5.2

�c [-]

V298 [m3/s]1.2 2.0 2.8 3.6 4.4

Com

pre

ssor

pre

ssur

e ra

tio

Volume flow

F31

F32

F33

TPS

48-

TPS

52-

TPS

57-

TPS

61-

TPS . .-E

TPS . .-D

Fig. 1a: Operating range of TPS. . -D/E/F [1, 2]. Fig. 1b: Cross sectional view of TPS. . -F [2].

5

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.

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.

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.

Power

NOx D

CO D

Opacity

HC W

0

10000

20000

30000

40000

0

1.0

2.0

3.0

4.0

10:01 10:59 11:57 12:54 13:52 14:49 15:47

Pow

er [k

W],

NO

x [p

pm

/10]

, H

C [p

pm

]

Op

acity

[%];

CO

[pp

m*1

00]

Time

Fig. 3: Example of dynamic measurement on a container ship.

Fig. 2: Ships for the load profiles and emission measurements by GL.

CMV Tokyo Express, main engine, 2002-12-27 – 2003-12-28

6

3 Controlled pulse turbocharging

Modifications to the pipe system and turbine stage are neces-sary to provide controlled pulse turbocharging of the engine.These are described below.

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.

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 �øbetween two cylinders in the same group satisfies the follow-ing conditions:�ø ≤ 120 °KW or �ø ≥ 240 °KW

3-pulse turbocharging satisfies the conditions and providesthe best compromise between pulse effect at part load andacceptable loss of efficiency at high engine power.

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.

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 2–2–1 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.

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.

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].

CYL3

CB 1

JCT 1PE 1 JCT 2 JCT 3 JCT 4 JCT 5

CB 2

CB 3COM 1

TUR1

CYL4

CYL5

CYL2

CYL1

Pipe 1

Pipe 11 Pipe 10 Pipe 9 Pipe 8 Pipe 7 Pipe 6

Pipe 2 Pipe 3 Pipe 4 Pipe 5

CYL3

CB 1

JCT 1

JCT 6 BL 1

BL 2 JCT 2

JCT 3

JCT 4

JCT 5

CB 2

CB 3COM 1

TUR 1

CYL4

CYL5

CYL2

CYL1

Pipe 1

Pipe 12Pipe 13

Pipe 14

Pipe 15

Pipe 11

Pipe 10 Pipe 9

Pipe 8Pipe 7

Pipe 6

Pipe 2 Pipe 3 Pipe 4 Pipe 5

Fig. 4: Original and optimized topology.

7

Fig. 6: Test engine with controlled pulse turbocharging.

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.

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.

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).

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.

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

possible

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.

1.5

220

bsfc [g/kWh]

100 %

210

200

2.0

2.5

�v

50 60 70

+4%

+1%

80 [mm]

Dpipe

1.5

220

bsfc [g /kWh]

40 %

VCL = Valves closed VO = Valves open SPS = Single pipe exhaust system

210

200

2.0

2.5

�v

50 60 70

+30 %

+20 %

80 [mm]

Dpipe

Fig. 5: Influence of the exhaust pipe diameter.

Control valves

8

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).

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.

During engine operation, every turbine inlet producesunsteady pressure curves with phase differences. Engine

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, sector transition losses caused by unequal admis-sion must also be taken into account.

Since measurement of these losses is extremely complex aprocedure involving loss models is used, being calibrated onthe basis of partial admission measurements. Measurementsunder partial admission conditions for a radial turbine withthree gas inlets were performed for the first time within thescope of the “SMOKERMEN” project (Fig. 8).

It can be seen that the efficiency loss of around 10 % at 2⁄3and 25 % at 1⁄3 admission is considerable. These are extremevalues, however, which do not occur during engine operationand are only used for calibration of the loss models.

Fig. 7: 3-inlet casing for TPS 48. Fig. 8: Measured turbine efficiencies with full and partial admission.

– 0.5

– 0.3

– 0.1

0.1

0.2

[-]

1.5 2 2.5 3 3.5 [-]

Turb

ine

effic

ienc

y lo

sses

Turbine pressure ratio

Full admission

Partial admission 2/3

Partial admission 1/3

TPS 52 turbine measurements

9

Fig. 10: Jet assist power referred to the turbine power. Fig. 11: Compressor model.

0

4

8

12

16

[-]

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 [-]

pA

ir In

j/P

T*10

0

n298/nref

pAir Inj

2.0 bar

4.0 barSimulation

Measurement

1

2

3

4

5

�V*[-]

1 2 3

0.464

0.652

0.781

0.868

n298/nref = 0.929

4 5 6

Measurement

Calculation

V298 [m3/s]

Fig. 12: Compressor simulation with and without jet assist.

1.0

2.0

3.0

4.0

5.0

�v* [-]

1

0.464

0.652

0.781

0.868

2 3 4 5 6

Without jet assist

With jet assist

V298 [m3/s]

n298/nref = 0.929

0

10

15

5

0.5 0.6 0.7 0.8

Air injection pressure = 4.5 bar

Additional torque [Nm]

n298

/nref

0.5

0.9

1.1

0.7

�sV

* [-]

1 2 3 4 5 6 V298

[m3/s]

Without jet assist

With jet assist

The injection of compressed air into the compressor channelsis a well-known measure ([5, 6]) for supporting turbochargeracceleration during transient operation of the engine. To allowthis a new insert wall was designed and produced for thecompressor stage (Fig. 9).

The solution included the flow-optimized design of the nozzlesand their optimum distribution around the periphery of theinsert wall. Special attention was paid to ensuring that inad-missible oscillations of the blades were avoided.

The system was initially tested on the turbocharger test bed in order to deduce the change in compressor behavior (Fig. 10). The most important changes observed are: – An additional torque on the turbocharger shaft. The cause

of this is firstly reduced loading of the compressor wheel(the compressor needs to take in and compress less airthan during normal operation to deliver the same outlet volume at the same pressure), and secondly the momentumtransmitted by the compressed air being blown onto thecompressor blades.

– A minor displacement of the compressor map (referred tothe outlet mass flow) towards higher pressure ratios andflow rates.

While the experimental tests were under way, a one dimensionalcompressor model was developed which, with the help of thediscretized compressor geometry as well as various loss models,firstly allows reproduction of the compressor map in normaloperation with a one dimensional flow calculation (Fig. 11) andsecondly serves to simulate with sufficient accuracy the addi-tional mass flow in jet assist mode and its effects (Fig. 12).

4 Jet assist operation

Fig. 9: Insert wall for jet assist.

10

5 Engine measurements

5.1 Steady-state engine operationImportant results are obtained from a comparison of the reference measurements carried out on the engine with theundivided standard exhaust gas pipe system and the meas-urements performed with a pulse exhaust gas pipe system.The turbocharger specification was the same for all measure-

ments, only the gas inlet casing being changed. The curves in Fig. 13 show the measured data without any correction. Itshould be noted in particular that the charge air temperatureis 30 °C higher in the reference data. The data should be nor-malized to allow a direct comparison.

20 40 60 80

Load

[%]

20

40

0

�bsfc

[g /kWh]

1 3

2

1

prec

[bar]

pc,max

[bar]

150

200

100

2

3

�v, eng.

400

500

600

TTI

[C]

Pulse system – valves closed

Pulse system – valves open

Constant pressure system

Fig. 13a: Engine measurements – generator curves.

20 40 60 80

Load

[%]

20

40

0

�bsfc

[g /kWh]

1 3

2

1

prec

[bar]

pc,max

[bar]

150

200

100

2

3

�v, eng.

400

500

600

TTI

[C]

Pulse system – valves closed

Pulse system – valves open

Constant pressure system

Fig. 13b: Engine measurements – propeller curves.

11

The results are briefly described below:

Upper load range, constant pressure turbocharging versus controlled

pulse turbocharging: The results for constant pressure turbocharging and

controlled pulse turbocharging with open valves are comparable. The

minor differences are due to the higher charge air temperature in the case

of constant pressure turbocharging.

Generator operation: Controlled pulse turbocharging with closed valves

exhibits up to 0.4 bar more charge pressure compared with constant pres-

sure turbocharging. The combustion air ratio therefore shifts from the opti-

mum range to higher values, so that fuel consumption rises. The exhaust

gas temperature is lowered slightly by the increased combustion air ratio.

Propeller operation: Operation with controlled pulse turbocharging and

closed valves results in an up to 30 % increase in the combustion air ratio

and 5 % reduced fuel consumption compared with constant pressure

turbocharging operation. The exhaust gas temperature is reduced by up to

200 °C. It should be noted that the layout of the constant pressure

turbocharging system for propeller operation is not optimal: in the normal

case, engines with constant pressure turbocharging for marine applica-

tions are provided with a waste gate and bypass. With a layout of this

kind, constant pressure turbocharging would behave in a similar way to

controlled pulse turbocharging at part load. In full load operation, however,

controlled pulse turbocharging would reveal advantages over constant

pressure turbocharging.

The absolute values of �v remain about 10 % lower than fore-cast in Fig. 5. This was expected, however, and can be attrib-uted to the losses due to unequal admission of the turbine.Further simulations taking account of these losses agree rea-sonably well with the values measured.

Valuable information concerning the behavior of the turbineand the pulse pipe system is provided by pressure measure-ments at the turbine inlets (Fig. 14). Examples are given ofpressures at the turbine inlet flanges at 60 % power on thepropeller curve with valves open and closed as a function ofthe crank angle. The typical pattern of pulse turbochargingwith large firing intervals can be recognized during operationwith closed valves. A peak in the blow-down phase, followedby a marked rise in pressure during discharge and a fall inpressure during the scavenging phase can be seen in all fivecylinders. This behavior favors scavenging of the cylindersand transmission of the pressure energy to the turbine. Thehigh counter-pressure during the exhaust cycle of the cylin-ders, however, is also responsible for relatively high gasexchange losses.

With the valves open it can be seen that the pressure peaksare only slightly reduced, but that in between a well balancedpressure is applied to all turbine sectors. This behavior isqualitatively similar to that of a multi-pulse system.

100

150

200

250

300

p after IC[kPa]

– 270 – 180 – 90 0 90 180 270 °CA

Pre

ssur

e b

efor

e tu

rbin

e

pinlet1

pinlet2

pinlet3

Fig. 14a: Engine measurements – pressure curves at turbine inlet.

Propeller law, 60 % load, valves closed

100

150

200

250

300

p after IC[kPa]

0 90 180 270 °CA

Pre

ssur

e b

efor

e tu

rbin

e

pinlet1

pinlet2

pinlet3

– 270 – 180 – 90

Fig. 14b: Engine measurements – pressure curves at turbine inlet.

Propeller law, 60 % load, valves open

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5.2 Transient operationA major objective of the “SMOKERMEN” project is the reduc-tion of smoke emission, particularly in transient operation.Numerous measurements were therefore carried out to deter-mine the load variations in generator as well as in propelleroperation.

Fig. 15 shows the engine behavior during a load step fromidling to a mean effective pressure of bmep = 9.3 bar at constant speed. The measured data are compared for engineoperation with the following turbocharging systems: – Constant pressure turbocharging– Constant pressure turbocharging with jet assist

(air pressure = 4 bar, injection duration = 6 seconds) – Controlled pulse turbocharging

It can be seen that with air injected the recovery time ofaround 9 is more than halved to 4 s. The maximum speeddrop changes less, however, from 9 % to 7 % and smokeemission cannot be avoided. The duration is in fact reducedfrom around 8 to 3 s, but opacity still reaches 100 %. To avoid this, the air injection would have to be switched on inadvance, which is not always possible, or the filling limit would have to be set lower.

The comparison of the reference configuration and pulse turbocharging exhibits somewhat poorer results for recoverytime and speed drop than with jet assist operation. The following deviations from the reference case can be found: 1. A higher initial pressure, 2. A higher or at least equal pressure gradient and3. Different torque gradients

The reason for the differences lies in the different tuning of thebrake controller. It can be expected with comparable settingsthat the engine with controlled pulse turbocharging will ex-hibit a similar behavior to constant pressure turbochargingand jet assist operation.

The opacity curve in the case of controlled pulse turbocharg-ing is noteworthy: although the engine is more heavily loadedcompared with the other cases, the maximum value remainsclearly below 100 %. The effect of pulse turbocharging isclearly apparent here, which also ensures good scavenging ofall cylinders immediately after the load is applied [3].

Fig. 16 shows the results of two load steps on the engine withCPT, namely from idling to an effective mean pressure ofbmep = 9.3 bar and 9.83 bar. It can be seen that even smallbmep differences can have a considerable influence on thetransient behavior of the engine.

0

25

50

75

100

[%]

1 2 3 4 5

Time

6 7 8 9 [s]

Op

acity

80

100

120

140

160

[kPa]

1 2 3 4 5

Time

6 7 8 9 [s]

p a

fter

IC

– 15

– 10

–  5

0

[%]

1 2 3 4 5

Time

6 7 8 9 [s]

Sp

eed

dro

p

0

1

2

3

[kNm]

1 2 3 4 5

Time

6 7 8 9 [s]

Torq

ue

SPS

SPS + jet assist

CPT

Fig. 15: Load acceptance test, bmep = 0 – 9.3 bar with and without jet assist.

0

20

40

60

80

[%]

1 2 3 4 5

Time

6 7 8 9 [s]

Op

acity

100

120

140

160

180

[kPa]

1 2 3 4 5

Time

6 7 8 9 [s]

p a

fter

IC

– 15

– 11

–  7

–  3

[%]

1 2 3 4 5

Time

6 7 8 9 [s]

Sp

eed

dro

p

0

1

2

3

[kNm]

1 2 3 4 5

Time

6 7 8 9 [s]

Torq

ue

0 – 47.5 %

0 – 45.0 %

Fig. 16: CPT/Load acceptance tests, bmep = 0 – 9.3 bar and bmep = 0 – 9.83 bar.

13

6 Combination of measures

The results from the previous chapter indicate that a significantreduction in smoke emission is possible with the measuresexamined.

The project target of “a smokeless engine” must be tackled at two levels. Firstly, a concept must be found for the turbo -charged engine, by which the engine develops as little smokeas possible in transient operation. Possibilities for this wereindicated in this article. Secondly, the engine control mecha-nisms available must be controlled with a suitable device, sothat operating conditions critical for smoke development areavoided. Associated control strategies are to be investigatedin a further phase of the project.

The following specific topics are to be examined:– Steady-state operation: For the control of pulse turbo-

charging the conditions for closing the valves must bedefined. To do this, the system behavior with intermediatepositions of the valves must be examined. So far, only theextreme positions of the valves have been tested (open and closed positions). In the intermediate range a certainthrottling in the connecting pipe can be beneficial.

– Transient operation: The control system must be designedsuch that in the event of large target /actual value devia-tions in engine speed or charge air pressure the valves areclosed, and so permit faster acceleration of the turbo-charger. Account must also be taken of the dynamics of the valves.

The effect of air injection and its parameters must also bedetermined experimentally for the engine with pulse turbo -charging.

At the same time, control algorithms must be prepared andtested to optimum checking of:– The valve positions for controlling the pulse system and air

injection– The filling limit for the injection system in steady-state and

transient engine operation.

14

7 Summary

A controlled pulse turbocharging system was designed,implemented and tested in the “SMOKERMEN” project.

The tests performed indicate that controlled pulse turbo-charging in steady-state part load operation as well as in transient operation allow efficient use to be made of theadvantages of pulse turbocharging. In the upper load rangeefficiencies comparable with those of constant pressure turbocharging can be achieved by opening the shutoff valves.The full potential of the presented pulse turbocharging system, however, can only be fully exhausted by means ofsuitable controls.

It was further shown that air injection also represents an efficient aid to acceleration with constant pressure systems. It is expected that the transient behavior of the engine will be significantly improved by the combined application of controlled pulse turbocharging and air injection.

AcknowledgementsThe SMOKERMEN project was made possible by financialsupport from the EU Commission and the Federal Departmentof Education and Science in Switzerland. The work was suc-cessfully performed in close collaboration with university andindustrial partners.

The authors wish to thank all project partners for the coopera-tive way in which the project was conducted.

15

Bibliography

[1] Born, H., R. Meier, M. Kahi & M. Seiler, 1997, Turbocharging Modern Diesel & Gas Engines up to 3200 kW, ASME, Fall Technical Conference, ICE-Vol. 29-1.

[2] Born, H., Ch. Roduner, M. Meier, 2004, TPS . . -F: A new series of small turbochargers for highest pressure ratios, CIMAC Congress, Kyoto, Paper no.: 34.

[3] Codan, E., 1993, Optimierung des Aufladesystems unddes Betriebsverhaltens von Grossdieselmotoren durchComputersimulaton, 5. Aufladetechnische Konferenz,Augsburg, pp. 19 – 36.

[4] Codan, E., 2000, Die Aufladung zukünftiger Gross-motoren, 7. Aufladetechnische Konferenz, Dresden, pp. 209 – 228.

[5] Codan, E., I. Vlaskos, O. Bernard & P. Neuenschwander,2002, Massnahmen zur Verbesserung des transientenBetriebs von turboaufgeladenen Grossmotoren, 8. Aufladetechnische Konferenz, Dresden.

[6] Ledger, J.D., R.S. Benson & H. Furukawa, 1973, Performance Characteristics of a Centrifugal Compressorwith Air Injection, Proc. I.Mech.E Vol 187 35 /73.

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ABB Turbocharging Service network

ABB Turbo Systems LtdBruggerstrasse 71 aCH-5401 Baden/SwitzerlandPhone: +41 58 585 7777Fax: +41 58 585 5144E-mail: turbocharging@ch.abb.com

www.abb.com/turbocharging

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