recent trends in internal combustion...

Advances in Mechanical Engineering

Recent Trends in Internal Combustion Engines

Guest Editors: Halit Yaşar, Hakan Serhad Soyhan, Adnan Parlak, and Nadir Yılmaz

Advances in Mechanical Engineering


Guest Editors: Halit Yaşar, Hakan Serhad Soyhan,Adnan Parlak, and Nadir Yılmaz

Copyright © 2014 Hindawi Publishing Corporation. All rights reserved.

This is a special issue published in “Advances in Mechanical Engineering.” All articles are open access articles distributed under theCreative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided theoriginal work is properly cited.

Editorial Board

Mehdi Ahmadian, USARehan Ahmed, UKMuhammad T. Akhtar, JapanNacim Alilat, FranceM. Affan Badar, USALuis Baeza, SpainR. Balachandran, UKAdib Becker, UKFilippo Berto, ItalyNoël Brunetière, FranceMustafa Canakci, TurkeyMarco Ceccarelli, ItalyFakher Chaari, TunisiaChin-Lung Chen, TaiwanLingen Chen, ChinaQizhi Chen, AustraliaLong Cheng, ChinaKai Cheng, UKHyung H. Cho, Republic of KoreaSeung-Bok Choi, KoreaAhmet S. Dalkilic, TurkeyJ. Paulo Davim, PortugalKangyao Deng, ChinaFrancisco D. Denia, SpainT. S. Dhanasekaran, USANihad Dukhan, USAFarzad Ebrahimi, IranAli Fatemi, USAMario L. Ferrari, ItalyLuı́s Godinho, PortugalRahmi Guclu, TurkeyTian Han, China

Ishak Hashim, MalaysiaDavood Jalali-Vahid, IranJiin Y. Jang, TaiwanXiaodong Jing, ChinaMitjan Kalin, SloveniaS.-W. Kang, Republic of KoreaMichal Kuciej, PolandYaguo Lei, ChinaZili Li, The NetherlandsYangmin Li, MacauJun Li, ChinaZhijun Li, ChinaJianguo Lin, UKCheng-Xian Lin, USAJian Liu, ChinaChen-Chi M. Ma, TaiwanSeyed N. Mahmoodi, USAOronzio Manca, ItalyRamiro Martins, PortugalFrancesco Massi, ItalyHua Meng, ChinaRoslinda Nazar, MalaysiaT. H. New, SingaporeCong T. Nguyen, CanadaHirosi Noguchi, JapanTakahito Ono, JapanHakan F. Oztop, TurkeyDuc T. Pham, UKIoan Pop, RomaniaJurij Prezelj, SloveniaXiaotun Qiu, USAPascal Ray, France

Robert L. Reuben, UKPedro A. R. Rosa, PortugalElsa de Sá Caetano, PortugalDavid R. Salgado, SpainMohammad R. Salimpour, IranSunetra Sarkar, IndiaPietro Scandura, ItalyA. S. Sekhar, IndiaLiyuan Sheng, ChinaXi Shi, ChinaSeiichi Shiga, JapanChow-Shing Shin, TaiwanAndrea Spagnoli, ItalyAnandThite, UKShan-Tung Tu, ChinaSandra Velarde-Surez, SpainJunwuWang, ChinaMoran Wang, ChinaJia-Jang Wu, TaiwanHongwei Wu, UKGongnan Xie, ChinaHui Xie, ChinaRuey-Jen Yang, TaiwanJianqiao Ye, UKChun-Liang Yeh, TaiwanBoming Yu, ChinaBo Yu, ChinaJianbo Yu, ChinaYufeng Zhang, ChinaMin Zhang, ChinaLing Zheng, ChinaZhaowei Zhong, Singapore

Contents

Recent Trends in Internal Combustion Engines, Halit Yaşar, Hakan Serhad Soyhan, Adnan Parlak,and Nadir YılmazVolume 2014, Article ID 143160, 1 page

Design and Implementation of the Control System of an Internal Combustion Engine Test Unit,Tufan Koç, Durmuş Karayel, Barış Boru, Vezir Ayhan, İdris Cesur, and Adnan ParlakVolume 2014, Article ID 914876, 9 pages

Trends of Syngas as a Fuel in Internal Combustion Engines, Ftwi Yohaness Hagos, A. Rashid A. Aziz,and Shaharin Anwar SulaimanVolume 2014, Article ID 401587, 10 pages

Simulation Analysis of Combustion Parameters and Emission Characteristics of CNG Fueled HCCIEngine, P. M. Diaz, N. Austin, K. Maniysundar, D. S. Manoj Abraham, and K. PalanikumarVolume 2013, Article ID 541249, 10 pages

Calibration and Validation of a Mean Value Model for Turbocharged Diesel Engine, Ruixue Li,Ying Huang, Gang Li, Kai Han, and He SongVolume 2013, Article ID 579503, 11 pages

Fuzzy Sets Method of Reliability Prediction and Its Application to a Turbocharger of Diesel Engines,Yan-Feng Li and Hong-Zhong HuangVolume 2013, Article ID 216192, 7 pages

EditorialRecent Trends in Internal Combustion Engines

Halit YaGar,1 Hakan Serhad Soyhan,1 Adnan Parlak,2 and Nadir YJlmaz3

1 Department of Mechanical Engineering, University of Sakarya, Esentepe Campus, Serdivan, 54187 Sakarya, Turkey2Marine Engineering Operations Department, Yıldız Technical University, 34349 Istanbul, Turkey3 Department of Mechanical Engineering, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA

Correspondence should be addressed to Halit Yaşar; [email protected]

Received 26 May 2014; Accepted 26 May 2014; Published 25 June 2014

Copyright © 2014 Halit Yaşar et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

This special issue is devoted to the recent trends in internalcombustion engines. Recent trends in internal combustionengines aim to reduce fuel consumption and also lowerexhaust gas emissions.The aim of this special issue is to bringall topics and all the scientific/technological approaches inrecent trends in internal combustion engines.

We, as editorial team, received several contributions asoriginal research articles and review articles that will stimu-late the continuing efforts to understand new technologies ininternal combustion engines (ICEs). The papers are “Designand implementation of the control system of an internalcombustion engine test unit” by T. Koç et al., “Trends of syngasas a fuel in internal combustion engines” by F. Y. Hagos et al.,“Simulation analysis of combustion parameters and emissioncharacteristics of CNG fueled HCCI engine” by P. M. Diazet al., “Calibration and validation of a mean value model forturbocharged diesel engine” by R. Li et al., “Fuzzy sets methodof reliability prediction and its application to a turbocharger ofdiesel engines” by Y.-F. Li and H.-Z. Huang.

Acknowledgments

We thank the authors for their contributions and the review-ers for their help in bringing this issue to its current form.We are grateful in this regard to the reviewers who helped usduring the reviewing process and selection of the papers.

Halit YaşarHakan Serhad Soyhan

Adnan ParlakNadir Yılmaz

Hindawi Publishing CorporationAdvances in Mechanical EngineeringVolume 2014, Article ID 143160, 1 pagehttp://dx.doi.org/10.1155/2014/143160

http://dx.doi.org/10.1155/2014/143160

Research ArticleDesign and Implementation of the Control System ofan Internal Combustion Engine Test Unit

Tufan Koç,1 DurmuG Karayel,1 BarJG Boru,1 Vezir Ayhan,2 Edris Cesur,2 and Adnan Parlak3

1 Department of Mechatronics Engineering, Technology Faculty, Sakarya University, 54187 Sakarya, Turkey2Department of Mechanics Engineering, Technology Faculty, Sakarya University, 54187 Sakarya, Turkey3 Department of Ship Machines Operating Engineering, Naval Architecture and Maritime Faculty, Yıldız Technical University,Istanbul, Turkey

Correspondence should be addressed to Barış Boru; [email protected]

Received 25 September 2013; Revised 2 December 2013; Accepted 5 December 2013; Published 10 February 2014

Academic Editor: Hakan Serhad Soyhan

Copyright © 2014 Tufan Koç et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Accurate tests and performance analysis of engines are required to minimize measurement errors and so the use of the advancedtest equipment is imperative. In other words, the reliable test results depend on themeasurement ofmany parameters and recordingthe experimental data accurately which is depended on engine test unit. This study aims to design the control system of an internalcombustion engine test unit. In the study, the performance parameters of an available internal combustion engine have beentransferred to computer in real time. A data acquisition (DAQ) card has been used to transfer the experimental data to the computer.Also, a user interface has been developed for performing the necessary procedures by using LabVIEW.The dynamometer load, thefuel consumption, and the desired speed can easily be adjusted precisely by usingDAQ card and the user interface during the enginetest. Load, fuel consumption, and temperature values (the engine inlet-outlet, exhaust inlet-outlet, oil, and environment) can beseen on the interface and also these values can be recorded to the computer. It is expected that developed system will contributeboth to the education of students and to the researchers’ studies and so it will eliminate a major lack.

1. Introduction

In recent years, an increase in the number of motor vehicleshas been witnessed. In parallel with this development, newissues such as energy saving, emission reduction, environ-mental protection, and demand for safety have been includedin the agenda of human beings.Thus, it has become necessaryto produce the engines which can meet these new require-ments.This case increases the importance of functional tests.Therefore, the researchers have focused their studies onthe development of new testing units. During engine tests,researchers have to control several parameters at the sametime and they need to record lots of data. By using PC-controlled and -automated engine test units, it is very easyto carry out tests with high precision. PC-controlled testunits are very expensive because of that many researchers donot have the ability to use them. In this study, we aimed to

implement a low-cost and fully automated engine controlsystem.

LabVIEW is a highly functional engineering graphicalprogramming environment which is widely used in research-es worldwide. LabVIEW has ability to connect several DAQcards and its program execution is based on data flow.Therefore, it is widely used for data acquisition, data analysis,and data control [1]. Using LabVIEW make it possible tocreate visual, flexible, and scalable laboratory programs. PC-controlled engine test unit should have lots of analog I/O anddigital I/O. In this study, a DAQ card has been chosen as PCI/O equipment. LabVIEWhas been chosen as a programmingenvironment because of its abilities.

A PC-controlled dynamical engine test and control couldbe used for engine’s transmission parts simulations. It is veryuseful for emission analysis and practical development ofemission preventing technologies [2]. Without using engine

Hindawi Publishing CorporationAdvances in Mechanical EngineeringVolume 2014, Article ID 914876, 9 pageshttp://dx.doi.org/10.1155/2014/914876

http://dx.doi.org/10.1155/2014/914876

2 Advances in Mechanical Engineering

test units, exhaust emission analysis has statistical and sys-tematic errors. By using PC-controlled engine test and con-trol unit some simulation procedures could be created andperformed.This is very accurate and robust way for emissionanalysis [3–5].

Bunker et al. [6] have been designed a control unit inorder to provide the control of an engine test unit and dyna-mometer. The diesel engine has been tested at the designedcontrol unit. As a result of experimental study successfulresults were obtained. Gubeli and Dorey [7] have designedan interface to control dynamometer at the engine test unit.Designed system can be made automatical according to dif-ferent working conditions.

Feng et al. [8] have designed an interface at the LabVIEWprogram to conduct engine test. The experiments have beencarried out on a SI engine. The system consists of the enginecontrol unit, DAQ card, computer, and some additional elec-tronic circuits as hardware. The system has tested basicallythree functions: ignition control, stepper motor control, andthrottle position control. As a result of the engine tests theengine that is designed ismore reliable and accurate data havebeen obtained from experiments.

Hafner et al. [9] have developed a software/hardwareenvironment for engine control systems.This dynamic enginetest stand has been qualified to perform functions such asdesign and tests for new control. The desired control settingshave been calculated by using the developed engine manage-ment system and developed optimization strategies bymeansof adequate models of the engine behavior with fast neuralnetworks. Benito et al. [10] have aimed to improve the real-time performance of some optimization algorithms used inengineering control units. A genetic algorithm (GA) has beenused to optimize the working parameters of a spark ignitionreciprocating engine. They have tried to find out the valuesof some engine control parameters such as intake pressure,intake pipe length, intake valve closing angle, and sparktiming that yield the requested engine power while requiringminimum specific fuel consumption. Wang et al. [11] havedesigned and developed a diagnostic tool based on KingtecStandard Diagnostic Protocol. A physical connection andlevel translation between personal computer (PC) and elec-tronic control unit (ECU) have been realized by using devel-oped special communication module. The system consistsof guidance service suggestion (GSS) function module andfundamental function module which have been designedwith Visual C++ and LabVIEW languages.They have showedthat the developed system could realize accurate and quickdata communication, online diagnostic management, real-time and dynamic measuring data refreshment, online pro-gramming data, and practical GSS.

Cerri et al. [12] have attempted to achieve high levels ofspecific power output and efficiency and so, they have carriedout an experimental activity to understand how each fuelsample could improve the performance of amodern naturallyaspirated SI (spark ignition) engine for passenger cars. Thisexperimental campaign has consisted in measurements ofthe maximum brake torque (MBT) curve up to knock onsetand the corresponding knock intensity, at wide open throttle(WOT) and partial load operating conditions, for each tested

gasoline sample. González et al. [13] have studied the simula-tion design of an engine control unit (ECU) for an Otto cycleengine with electronic fuel injection (EFI) using Simulinkand Stateflow.Their simulation includes a model for the ECUas well as physical parameters of the engine, which allowsclosed-loop control and monitoring of various systems. Thestudy allows controlling of various parameters of the ECUusing an open-loop control. They have used this simulationfor gas emission, fuel economy, and engine performanceimprovement purposes. Antonopoulos et al. [14] have real-ized an experimental investigation on a single cylinder dieseltest engine to identify the aforementioned problem. Theyhave recorded cylinder pressure and instantaneous speedduring the tests.The comparison of the two cylinder pressuretraces and the thermodynamic parameters derived fromthem reveals the introduction of an error which depends onengine load and speed. Taglialatela et al. [15] have proposedthe use of a multilayer perceptron neural network to modelthe relationship between the engine crankshaft speed andsome parameters derived from the in-cylinder pressure cycle.They have demonstrated an application of neural networkmodel on a single-cylinder spark ignition engine tested ina wide range of speeds and loads and have confirmed thata good estimation of some combustion pressure parame-ters can be obtained by means of a suitable processing ofcrankshaft speed signal.

Scattolini et al. [16] have presented a model and a simula-tion environment in order to characterize new throttle bodiesand to design the associated control algorithms. Thus, theycan properly regulate the additional air flow provided to theengine in idle speed conditions. Isermann and Müller [17]have explained the structure of a rapid control prototyping(RCP) system, which allows for fast measurement signalevaluation and rapid prototyping of advanced engine controlalgorithms. Providing efficient engine models for the pro-posed development tools, a dynamic local linear neural net-work approach has been explained and applied for modellingthe NOx emission characteristics of a direct injection dieselengine. Finally, they have presented the simulation resultsfor a 40-ton truck. Chung et al. [18] have proposed a real-time estimation algorithm of combustion parameters. Theproposed estimation algorithm uses the difference pressureonly instead of the in-cylinder pressure for calculation of thecombustion parameters and it requires only 51% of the execu-tion time to calculate the combustion parameters comparedto the conventional method. They have validated the pro-posed estimation algorithmwith an engine experiment under131 operating conditions that showed high linear correlationwith the original combustion parameters.

Franco et al. [19] have presented a real-time engine braketorque estimation model where the instantaneous measuredengine speed serves as the model input. The engine braketorque estimation has been separated into two parts: steadystate and transient in their study. They have provided valida-tion of the engine brake torque model using a computationalengine model for a 6-cylinder heavy duty diesel engine.Mart́ınez-Morales et al. [20] have presented a neural networkmodel of internal combustion engine in their work. At first,they have collected data of a 1.6 L gasoline engine which has

Advances in Mechanical Engineering 3

been used for deriving an engine neural model. Three inputssuch as engine speed, injection angle, and the amount ofinjected fuel have been included to the system into a specificvalue range and then emissions have been measured. Theresults obtained showed the effectiveness of the proposedapproach in modeling the studied gasoline engine.

Here, we have tried to choose the most relevant ones toour study of studies. Almost, all of the studies are originaland also they provide significant contribution to the worldof science. However, each of them is focused on one ora few parameters. Also, they have a rigid structure andto use them for other parameters on similar researches isdifficult. However, our available study has a flexible structurecompletely.The desired parameter can be added and removedvery easily. Therefore, the developed system can be adaptedto all engine tests with only a few arrangements. In thisrespect, this systemcan also be used for educational purposes,including distance education, as well as professional enginetests. In other words, the system has a universal structure andis suitable for both testing and control.This case is distinctivefeature of this study.

This study is organized as follows: at first, an introductionand literature review are presented. Section 2 gives mate-rial and methods. Section 3 illustrates experimental studies.Section 4 presents the results and discussion, and section fivedescribes the conclusions of the study and future works.

2. Materials and Methods

Framework and mechanical equipment of the test standof which the control system will be developed are alreadyavailable. The developed control system has been adapted tothis current mechanical system. LabVIEW software has beenused to design the control system. It is a highly productivedevelopment environment and is very suitable for real-timecontrol applications. The engine operating data such as load,temperature, speed, and instantaneous fuel consumptionhave been transferred to a computer by using data acquisitioncard in real time. At the same time, the engine throttle controlhas been controlled by a servomotor and also the load ofthe dynamometer has been controlled by applying voltage tothe setting input. These controls are real-time processes too.The USB-6251 DAQ card which produced by the NationalInstruments company has been used in the control system.The 6251 DAQ card has been preferred because it has theanalog/digital input and output channels and provides therequired specifications. Data to be read from the enginehave been received by means of analog/digital inputs of thedata acquisition card and then the parameters needed to beadjusted have been controlled by using analog/digital outputs.The overview of the designed engine test stand in Figure 1 andits block diagram in Figure 2 have been given respectively.

The prepared interface and program have been developedusing national instruments “LabVIEW” software. LabVIEWsoftware has a high capability for real-time data acquisitionoperations and can operate fully compatible with the dataacquisition card and so it has been preferred for this study.

Inlet and outlet temperatures of the engine coolant,engine oil temperature, and atmosphere temperatures have

Figure 1: Experimental setup.

been measured by NTC type thermistors. NTC thermis-tor’s resistance changes negatively according to temperatureincrease. Practically thermistor resistance value was mea-sured as analog voltage using a reference serial resistor. Inthis study, NTC thermistors are read by DAQ card analoginputs. Measured voltage converted the temperature by usingformula (1):

𝑇 = [1

𝑇𝑅

+1

𝛽ln( 𝑉(𝑉𝑖− 𝑉))]

−1

, (1)

where 𝛽 is the gain coefficient of thermistor (fixed), 𝑇𝑅is the

reference temperature (kelvin),𝑇 is actual thermistor temper-ature (kelvin), 𝑉 is thermistor voltage, 𝑉

𝑖is Input reference

voltage.Exhaust temperature is extremely high.Therefore, a ther-

mocouple with a maximum range of 1200∘C is used to mea-sure exhaust temperature. Thermocouple produces a voltageoutput according to temperature. But this voltage should befiltered and linearized. Therefore, in this study, a controldevice (EMKO ESM-4400) is used. This device produces 0–10V linear voltage output for measuring range of thermo-couple. Measured voltage for thermocouple converted thetemperature by using formula (2):

𝑇 =𝑉read0.0083, (2)

where 𝑇 is thermocouple temperature (celsius) and 𝑉read isthermocouple control device output voltage.

The engine speed has been read from the counter inlet ofthe DAQ card by means of encoder. The encoder measuresthe output pulse intervals from outlet of channel Z. ChannelZ of the encoder gives a pulse for every 3600. Hence, theinterval between the two pulses taken consecutively fromthe Z channel of the encoder represents the period taken tocomplete a cycle. Therefore, counter inlet of the DAQ cardand the Z channel pulse interval have been measured inseconds.Themeasured cycle time is divided by 60 and so it isconverted to rev/min. Load of the motor has been measuredwith a load cell connected to the dynamometer force arm.

The fuel consumption in mass has been measured byusing the load cell that has 0.1 g accuracy and connected to thefuel tank. The mass of the fuel tank during the test has been


Water tank

Engine

Emissiondevice

Dynamometer

Dynamometer

control

panelComputer

(labVIEW software)

Precision scale

Fuel tank

DAQ cardEncoder

ThermocoupleThermocouple control device

Thermistor 1

Thermistor 3

Thermistor 4

Thermistor 2Water inlet temperature

Water outlet temperature

Atmosphere temperature

Exhaust

USB 2.0RS-232

RS-232RS-232

Measuring

Dynamometer

Shaft

Water inletWater outlet

Servo motor

Throttle controlOil temperature

load amount

load setting

temperature

Figure 2: Experimental setup block diagram.

read at the beginning of the experiment and at the end of theexperiment and then the difference has been divided by totaltest time and so the instantaneousmass fuel consumption hasbeen measured as g/s.

The throttle control has been controlled by the servomo-tor and the servomotor has been controlled by using digitaloutputs of the data acquisition card too. This digital outputproduces a PWM signal for servomotor driving. The PWMsignal is produced by hardware timer module of DAQ card.

The control of motor load has been achieved by changingthe voltage value of the electric dynamometer. These voltagevalues have been controlled by using the analog outputs ofthe data acquisition card through the interface.Theminimumandmaximum voltage values of the dynamometer panel havebeen determined and these values have been entered to theinterface as the lower and upper limits.The interface can real-ize load control of the dynamometer by voltage control of thelower and upper limits. Ranges and tolerance of measuringdevices used in this study are given in Table 1.

In the experiments, an emission device branded BILSAhas been used to measure emissions. This device can com-municate with the designed interface by means of serial port(RS-232) in real time. The resulting emissions are recordedas log file. This electronically controlled test system providesthat the engine test steps are automated, the measured valuescan be seen on the interface, and the test results are recorded.Designed interface can be used for both modes as manualcontrol and full-load test mode.

After preparing experimental setup and LabVIEW pro-grams for measurement, systematic errors have been calcu-lated and are given in Table 2.

2.1. Manuel Control Mode. In the manual control mode,the test unit is controlled by the user manually. Positionof the throttle control and the voltage value applied to thedynamometer can be controlled by the user in real time whilethe program is in manual control mode. Whereby, adjustingprecisely the required speed and load can be possible. Fur-thermore, after setting the required speed and/or load, thedata are recorded to the computer as log file through “Importdata” button situated at the interface. Designed interface canbe operated into the two modes including manual controland a full-load test mode. Also, in manual control mode, toperform partial load tests is aimed. In this mode, the systemhas opportunity to perform experiments in the partial loadbecause load and speed are controlled by user.

2.2. Full-Load Test Mode. In full-load test mode, the controlof the system is taken from the user and all of the activities arecontrolled by the designed interface. In thismode, the desiredengine speed is entered into the interface of the system andthen the start button is pressed and so the designed interfacecontrols the throttle control in its initial state. At the sametime, the voltage value at ends of dynamometer is increasedand so reaching tomaximummotor speed is prevented. Afterthe throttle control arrives at the full throttle position, valueof the voltage applied to the dynamometer is changed bythe program until the desired speed is achieved. When thedesired motor speed is achieved by means of the program,the system waits to remain constant the exhaust temperaturedata and the data are saved to the computer as log file whenthe temperature reaches a constant value.

If a full-load test is required, after the mode is selected, itis sufficient that the user only enters the desired speed value.


Table 1: Sensor measuring ranges and tolerances.

Device Brand Range ToleranceThermocouple EMKO Max. 1200∘C ±2∘CThermocouple control devices EMKO ESM-4400 0–10V ±0.016VThermistor ENDA −50∘C–110∘C ±1∘CPrecision scales DIKOMSAN Max. 3000 g 0.01 gLoad cell ESIT S Type Max. 50 kg % ±0.05Incremental encoder Heidenhain ROD-426 3600 pulse/tour 1/20

Table 2: Systematic errors.

Parameters Systematic errors, ±Load, (𝑁) 0.1Speed, (d/d) 1.0Time, (s) 0.1Temperature, (∘C) 1Fuel consumption, (g) 0.01NO𝑥, (ppm) 5

CO, (%) 0.06HC, (ppm) 12CO2, (%) 0.5

Desired test conditions can be accomplished by obtainingthe desired speed value as a result of the load control. Theoperating principle of the full-load test mode is presented asthe block diagram in Figure 3.

In full-load test mode, a closed-loop control system hasbeen prepared to control the engine speed using the dyna-mometer load voltage. For the designed controller, the pro-portional control structure has been preferred. As is known,the response times of engine and dynamometer vary for dif-ferent combinations of load and motor speed. Therefore, theadaptation of time-dependent structures such as PD (propor-tional derivative) or PID (proportional integral derivative)controllers to this system is highly difficult while they canquickly reach stability state. The proportional controller hasbeen used because the accuracy is more important than theoperational time to create desired experimental conditions.The proportional controller has been used because the accu-racy ismore important than the operational time to create thedesired experimental conditions.

3. Experimental Studies

The experimental study has been performed on a two-cylinder and water cooled Lombardini SI engine. Engine teststand has been prepared with measurement devices men-tioned above according to software and interface design. Thecharacteristics of the engine used in the experiment have beenpresented in Table 3.

In this study, full-load test has been preferred as the firstexperiment and so the speed has only been entered in theuser interface and then all of the procedures took placeautomatically without any user interaction. In this mode,the designed program switches throttle control and the

Table 3: The Characteristics of the engine used in the experiment.

Engine type LombardiniPiston diameter (mm) 72Stroke (mm) 62Number of cylinders 2Stroke volume (dm3) 0.505Power (kW) 15Compression ratio 10.7Cooling type WaterInjectıon type Direct injection

dynamometer load to passive mode and does not allow userto interact. By entering speed value, the program sets to thedesired speed value of the engine by itself.The program trans-fers the measured data to the computer when the exhausttemperature arrives to a constant value. The interface of thesystem during a test step has been presented in Figure 4.

The experiments have been realized (carried out) in theengine speed range from 1600 rpm to 3600 rpm.The recordeddata have been also transferred to excel program. The screenoutput in excel programof the obtained data for full-load testshas been shown in Table 4.

The partial load tests have been performed at the manualcontrol mode. In partial load tests, the throttle control andthe dynamometer load are controlled by the user and thedesired speed and/or the dynamometer load adjusted by theuser. Data import process is realized by pressing the dataacquisition button when the engine speed and/or the loadreaches the desired values, if it is demanded by the user. Thepartial load tests have been also realized in the engine speedrange from 1600 rpm to 3600 rpmand the systemhas receiveddata at the beginning of each increase of 400 rpm as was donein the full-load test mode. Also, in this mode, the recordedexperimental engine speed data can be transferred to excelprogram as in the full-load mode.

4. Results and Discussion

A gasoline engine is used in the experiment. The full-loadlimit is point that consisted of knocking. After the engine isworked at theWOT (wide open throttle), the throttle is fixed.Full-load test is made by changing the setting of the load onthe control dynamometer. In this case, the load dynamometercontrol system is working to stabilize the cycles. Several tests


Table4:Th

edatao

btainedfro

mfull-load

tests

.

Speed

(rpm

)Lo

ad(kg)

Fuel

consum

ption(g)Instantaneou

sFuel

consum

ption(g/s)

Water

inlet(∘C)

Water

outlet(∘C)

Oil

(∘ C)

Atmosph

ere

(∘ C)

Exhaust

(∘ C)

O2

(%)

HC

(ppm

)CO (%

)CO

2(%

)NO𝑥

(ppm

)SO

2(%

)To

rque

(Nm)

Effectiv

epo

wer

(kW)

Specificfuel

consum

ption

1605.32

7.948.31

0.403

5261

6528

376

3.07

377

1.42

11.62

1753

0.0

29.44962

4.948228

293.1959

2005.15

8.1

61.20

0.510

5564

71.2

28456

1.98

356

1.25

12.51

2196

1.130.19

518

6.337134

289.7

209

2403.17

8.5

73.60

0.613

5767

7528

490

2.50

302

1.56

12.14

2232

1.231.6863

7.970112

276.8844

2806.238.4

86.74

0.723

6071

79.9

29522

2.61

287

1.48

11.98

2399

1.231.31

352

9.197368

282.994

3204.78

8.2

100.10

0.834

6273

8529

532

2.73

281

1.62

11.86

2427

1.430.56796

10.25352

292.8165

3606.12

7.8118

.180.985

6777

9630

548

1.68

286

4.02

10.99

1343

1.529.07684

10.97478

323.1045


Encoder

CounterPID controller

Analog Charging

voltage output

Requested speed (rpm)

EngineDynamometer control panel

ServomotorTimerRequested throttle level position

−+

Figure 3: Block diagram of full-load test.

Figure 4: The output of the interface taken during full-load test.

have been performed for verification performance of the con-trol systemdeveloped in this study. As a result of experiments,the engine speed has been fixed as error range of ±6 speed.

For verification, experiments are done with/without theengine control system in the same situations and results arecompared. Also, torque, instantaneous fuel consumption, andeffective power graphics have been drawn in excel. It hasbeen shown that the engine performance curves are correctaccording to the graphs and so the developed systemhas beenverified. Some of the performance and emission curves havebeen presented in Figure 5.

5. Conclusions

In this study, the design of the control system of an inter-nal combustion engine test unit has been developed andimplemented. The developed data acquisition and controlsystem have been successfully integrated with themechanicalstructure of the available test stand. Finally, the verificationtests have been realized by using the reference data provento be true their results. The experiment results have showedthat the designed system has a good performance to meetthe expected requirement. The conclusions drawn from thisstudy can be summarized as follows.

(i) Thanks to the developed system, researchers haveregained modern experimental environment. Hence-forth, all processes of the manual engine test benchcan be realized by the aid of computer in real time.

(ii) Engine performance parameters can be monitoredand analyzed on the computer screen in real time byusing the developed system.

(iii) The new system has superior properties such as thehigher measurement accuracy, reliability, and theshorter measurement period according to the classi-cal system. Also, themeasurement errors are reduced.

(iv) Thanks to the user interface, testing and control oper-ations have become easier so that even a person alonecan perform all the experiments.

(v) In addition to scientific studies, it will contribute toeducation and training activities especially in distanceeducation because it has rich visuals. It is usually diffi-cult to teach students who do not have an automationand engine background. However, to use this systemwill help students in understanding important testfunctions.

(vi) The measurements can be recorded easily, and so therelations between the different parameters can beobserved more easily.

(vii) The cost of the system is very low according to itscommercial competitive products which have similarcharacteristics.

(viii) Remote measurement capability of the system pro-vides noiseless and safer working environment to thetest personnel.

Wehope that the developed systemwill provide an impor-tant contribution for researchers, employees and education-training activities.The research results provided a foundationfor the further study. Future step based upon this work willbe on the internal combustion engine tests using artificialintelligence technologies as control algorithm.

Nomenclature

DAQ: Data acquisitionI/O: Input/outputSI: Spark ignitionNTC: Negative temperature coefficientPWM: Pulse-width modulationRS-232: Serial communication portPD: Proportional derivativePID: Proportional integral derivativeRPM: Revolutions per minuteWOT: Wide open throttle.


10.00

10.50

11.00

11.50

12.00

12.50

13.00

1600 2000 2400 2800 3200 3600

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STD

CO2

(%)

(a)

STD

0.00

0.50

1.00

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CO (%

)

(b)

STD

25

26

27

28

29

30

31

32

33

1600 2000 2400 2800 3200 3600

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Torq

ue (N

m)

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2

3

4

5

6

7

8

9

10

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12

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W)

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100

150

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(ppm

)

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500

1000

1500

2000

2500

3000

1600 2000 2400 2800 3200 3600

Engine speed (rpm)

STD

NO

x(p

pm)

(f)

Figure 5: Some of the performance and emission curves.

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper.

Acknowledgments

This study was supported through the interdisciplinaryproject numbered 2012-05-04-012 by Sakarya University,

Head of Scientific Research Commission. The authors grate-fully acknowledge the sponsoring of this work by SakaryaUniversity, Commission for Scientific Research Projects.

References

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Review ArticleTrends of Syngas as a Fuel in Internal Combustion Engines

Ftwi Yohaness Hagos,1 A. Rashid A. Aziz,1 and Shaharin Anwar Sulaiman2

1 Centre for Automotive Research and Electric Mobility (CAREM), Universiti Teknologi Petronas, Bandar Seri Iskandar,31750 Tronoh, Perak, Malaysia

2 Department of Mechanical Engineering, Universiti Teknologi Petronas, Bandar Seri Iskandar, 31750 Tronoh, Perak, Malaysia

Correspondence should be addressed to Ftwi Yohaness Hagos; [email protected]

Received 16 September 2013; Accepted 17 November 2013; Published 30 January 2014

Academic Editor: Nadir Yılmaz

Copyright © 2014 Ftwi Yohaness Hagos et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

Syngas from biomass and solid waste is a carbon-neutral fuel believed to be a promising fuel for future engines. It was widelyused for spark-ignition engines in theWWII era before being replaced with gasoline. In this paper, the technological development,success, and challenges for application of syngas in power generating plants, the trends of engine technologies, and the potentialof this fuel in the current engine technology are highlighted. Products of gasification vary with the variation of input parameters.Therefore, three different syngases selected from the two major gasification product categories are used as case studies. Their fuelproperties are compared to those of CNG and hydrogen and the effects on the performance and emissions are studied. Syngaseshave very low stoichiometric air-fuel ratio; as a result they are not suitable for stoichiometric application. Besides, syngases havehigher laminar flame speed as compared to CNG. Therefore, stratification under lean operation should be used in order to keeptheir performance and emissions of NOx comparable to CNG counterpart. However, late injection stratification leads to injectionduration limitation leading to restriction of output power and torque. Therefore, proper optimization of major engine variablesshould be done in the current engine technology.

1. Introduction

Scarcity of conventional petroleum resources and advance-ment in the solid-to-gas conversion technologies has revivedinterest in the use of solid fuels. Among the conversion tech-nologies, gasification is the most reliable and energy efficientwith advantages in both upstream and downstream flexibility[1]. It is a thermochemical conversion process that increasesthe hydrogen-to-carbon ratio of the feedstock by breakingcarbon bonds and adding hydrogen to the gaseous products[2]. When high carbon solid fuel reacts with a controlledamount of gasifying agent at an elevated temperature of morethan 600∘C, carbon monoxide (CO) and hydrogen (H

2) are

formed as depicted in (1). The process is called gasificationand the produced gas is called syngas.This process consists ofmany reactions and details about the gasification process canbe found elsewhere [2].This conversion process is believed to

be the major source of energy in the future, and instrumentalin the move from carbon based to hydrogen based energy [1]:

Carbonaceous Fuel + Limited air

= O +H2+ CH

4+ CO2+H2O +N

2

(1)

Syngas, an abbreviation for synthesis gas, is an endproduct of gasification. This is a name given for a mixturemainly comprised of CO andH

2at varied proportions. It also

consists of other gases like methane, nitrogen, and carbondioxide apart from thesemajor gases. It can be produced fromdifferent feedstock like coal, liquid hydrocarbons, biomass,and other waste products and the quality varies depending onthe feedstock and the gasification process.The name “syngas”is a general term for any gasification product. However,different names were used for different products at different

Hindawi Publishing CorporationAdvances in Mechanical EngineeringVolume 2014, Article ID 401587, 10 pageshttp://dx.doi.org/10.1155/2014/401587

http://dx.doi.org/10.1155/2014/401587


times in the past such as town gas, water gas, producer gas,and blast furnace gas [3].

The gasifying agent is the most significant parameter thataffects the yield from the thermochemical conversion process[2].Themain gasifying agents used in the process are oxygen,steam, and air. Syngas produced using steam or oxygenas a gasifying agent is called medium calorific value syngas(simply syngas) with its heating value range of 10–28MJ/Nm3[2]. On the other hand, syngas produced using air as a gasify-ing agent is called lower calorific value gas or “producer gas”and its heating value ranges from 4 to 7MJ/Nm3 [2]. Syngascan be used as a standalone fuel for power production or asan intermediate product in chemical industry for the pro-duction of synthetic natural gas, synthetic liquid petroleum,ammonia, and methanol [4].

A majority of research in the field of syngas utilizationhave been focused on its use as a direct fuel in integratedgasification combined cycle (IGCC) [4–10] and in the fuel andchemical production, where syngas is used as an intermediateproduct [4]. However, internal combustion engine (ICE) isthe most vital technological advancement, playing a majorrole in the distributed energy power generation for a variablepower output requirement. It has very flexible application inmoving and stationarymachineries. Compared to other typesof combustion technologies, ICE is believed to have benefitslike low capital cost, reliability, good part-load performance,high operating efficiency, and modularity and is quite safe touse. Because of this, utilization of syngas in these engines isnoteworthy; yet research in this area has been very limited[4, 11].The constituent of syngas that comes from gasificationlacks consistency. Besides, there were misconceptions aboutsyngas autoignition tendency at higher compression ratiosand power derating which later were explained elsewhere[11, 12]. These were the two reasons for the lack of adequateresearch in the area.

2. Technological Development

The era of using oils (such as olive, sesame, nut fish, whale,and beeswax) for lighting was transformed into gas lightingat the end of 18th century. Initially streets used to get lightfrom the hanging of door lamps facing the street. The ideaof public street lighting was initiated after the discovery offlammable gas from coal byWilliamMurdoch, who first usedit to light his house in 1792. This was further strengthenedby Frederick Albert Winsor, who got first patent in coal gaslighting in 1804 [17]. In 1799, a French engineer and chemist,Philippe Lebon patented his “thermolamp” which burned adistilled gas from wood [18]. This was the cornerstone fortechnological development of gasification and application ofits products for lighting. This technology was later expandedto elsewhere to theWestminster Bridge (London) in 1813 andthe city of Baltimore, MD, in the USA in 1816. It was furtherspread into major industries for lighting so that productivitycould be stretched into the night shift [3].

The application of this gas in automotive technologywas possible in the 1920s. In 1923, for instance, a Frenchinventor Georges Imbert (1884–1950) developed a wood gas

generator for mobile application [19]. Up to 9,000 vehicleswere produced with Imbert technology until the end of 1930s[20]. In the later years, mass production of automobiles withthis technology continued including companies like GeneralMotors, Ford, and Mercedes-Benz.

World War II led to the shortage of gasoline and as aresult development ofwood gas vehicles expanded all over theworld, which saw production of more than a million of suchvehicles [20].The number of cars running on producer gas atthe time of WW II was estimated at 7 million [21]. Germanywas leading with over 500,000 vehicles on the ground.Countries like Sweden, France, Denmark, Austria, Norway,and Switzerland were also on the list [20].

Petrol domination at the end of 1940s led to a quick exitof these Imbert-technology engines from the market. Sincethen, application of syngas shifted into integrated gasificationcombined cycle as a stationary power generation system.However, even at the moment, certain countries have nottotally given up on the use of such fuel inmobile engine appli-cations. USA is promoting the application of this technologyas a backup energy supply source in the event the countryfaces petroleum crisis [22].

3. Syngas in Stationary Power Plant

Since the end of World War II, research and development onsyngas application have shifted focus into stationary powergeneration. On top of this, coal, which is a prime fuel forsteam and gas power plants, has been branded the most envi-ronmentally pollutant fuel. This has forced countries to drawstringent regulations on direct firing of coal and other solidfuels [2]. These two factors led to research into upgrading ofsolid fuels. Besides reducing pollutant emissions, the upgrad-ing process of solid fuels through the gasification processhas other advantages such as easy handling and flexibilityof feedstock ranging from agricultural residue to municipalwaste. The earlier versions of gas turbines were primarilyfuelled on natural gas. However, since the oil crisis of 1970sthere have been many commercial installations of syngasfuelled integrated gasification combined cycle and gasifica-tion cofiring plants globally. The feedstock for most of themwas coal and petroleum coke. There are also some installa-tionswith biomass and solidwaste as feedstock. General Elec-tric (GE) has led in the technology development of syngas andother lower calorific value gas turbine technology in the last20 years. Up to 2007, GE was operating gas turbines with atotal capacity of more than 3GW in 15 plants (25 turbines)installed in USA, Canada, Singapore, Germany, Italy, TheNetherlands, and Czech Republic [23].

Gas turbine burners have been designed formonocompo-nent gaseous fuels (such as compressed natural gas (CNG))and as a result fuelling of syngas in such burners wouldlead to problems. The problems are associated with variedcomposition of component gases, high hydrogen content,and high volume flow rate requirements to maintain com-parable gas turbine efficiency [9, 24]. These issues, in turn,lead to flashback, flame oscillation under lean operation,autoignition of hydrogen at higher temperature and pressure,


component overheating, handling problem of high flow ratefuel in the combustor, and compressor instability. Summaryof these problems are explained elsewhere [24]. Besides, thereis risk of high nitrogen oxides (NOx) emission consequentto high reactivity of hydrogen component of the fuel. Manyresearch efforts have been undertaken globally to tackle theaforementioned problems [8, 9, 23, 25].

Direct coupling of gas production and power generationplants such as gas turbine or ICE have technical and economi-cal drawbacks.The gasifiermust be sized to fit the syngas end-use (gas turbine or ICE) [26]. Besides, such direct couplinglacks the flexibility to run the two plants separately.Therefore,introduction of syngas storage will enable utility stations tooperate their power plant during peak demandwhile runningthe gas production syngas as per production schedule. Thereare few researches on the introduction of a syngas storagesystem in an integrated gasification combined cycle and smallscale gasification plants, in which, gas production and powergeneration work separately and independently [26–28]. Yanget al. [29] reported that syngas can be stored with no effecton the chemical composition under temperature range of−15∘C to 45∘C and pressure up to 83 bar [29]. Introduction ofstorage has both technical and economic advantage accordingto a study by the National Energy Technology Laboratory(NETL) [26]. In comparison with other storage mechanisms,the study by the National Energy Technology Laboratory alsoemphasized that storage through compressed gas technologyhas some advantages such as its large-scale applicability andthe fact that is less expensive than other methods.

4. Syngas in Internal Combustion Engine

Engines are divided intomobile and stationary types depend-ing on their applications. The engines used in stationaryapplications are of both internal and external combustiontypes while mobile type engines are only of internal combus-tion types. ICE is the most vital technological advancement,playing a major role in distributed energy power generationespecially when there is a need for a variable power output.Theyhave very flexible application inmoving andnonmovingmachineries. ICE is believed to have benefits like low capitalcost, reliability, good part-load performance, high operatingefficiency, and modularity and are quite safe to use as com-pared to other types of combustion technologies [4].

The prospect of syngas as a fuel in ICE is believed to bevery promising and cost competitive when compared withnatural gas [4]. ICE is more tolerant towards contaminants ascompared to gas turbines. Even though they are not signif-icant in number like in the area of IGCC, there are someresearch works in the area of syngas utilization in ICE.These researches can be categorized into spark-ignition (SI)application specifically in the naturally aspirated carburetedand port injection type and dual-fuel compression ignition(CI) engines. Carbureted and port injection engines mixthe fuel and air prior to the combustion chamber and thevolumetric efficiency of the engine drops at the cost of thevoluminous syngas displacing air. Furthermore, they havehigher pumping and heat losses as compared to direct

injection (DI) SI engines, resulting in high fuel consumption[30]. Consequently, the theoretical power output of syngas-fuelled carbureted and port-injection engines is lower thanthose of gasoline and CNG. In DI systems, fuel is mixed withair in the combustion chamber and there is no restrictionto the amount of air aspirated into the chamber. Apart fromother engine operating parameters, syngas-fuelled enginewith a DI system is expected to have better engine poweroutput. However, based on an extended literature survey onDI SI fueled with syngas has never been studied.

4.1. Syngas as a Dual Fuel in CI Engine. Stringent regulationstowards the emissions from diesel engines are restrictingdevelopment of the most efficient ICE. Application of syngasin diesel engines is considered to be a viable alternative bothfor the emissions and energy crises. However, syngas has highself-ignition temperature (typically above 500∘C) and as aresult, it cannot be ignited by compression ignition in a dieselengine. A possible way of utilizing syngas in the CI engine isthrough dual fuelling, where diesel is injected as a pilot fuel toinitiate the ignition while syngas injected into the inductionsystem. The main motivation in using syngas and othergaseous fuels in diesel engine is as a substitute to diesel as thiscan consequently reduce cost, minimize emissions (NOx andparticulate matters), and increase the engine performance.

There aremany reports on research regarding syngas dualfuelling in CI engine. Azimov et al. [31] investigated the effectof H2and CO

2contents in syngas on the performance and

emission of a four-stroke single cylinder engine [31]. Dieselwas used to assist the autoignition of syngas in a pilot-fuelmode under lean condition for a wide range of equivalenceratio (𝜙). The engine was supercharged and operated in apremixedmixture ignition in the end-gas region (PREMIER).PREMIER combustion was observed for all syngas fuels,mainly when the pilot fuel used is very small. This combus-tionwas observed enhancing the performance and increasingthe efficiency of dual fuelling. Furthermore, they reportedthat an increase in hydrogen composition in syngas short-ened the main combustion duration and thereby causing anincreasing in the mean combustion temperature, indicatedmean effective pressure (IMEP), and efficiency. However,neither diesel could be completely substituted nor couldsyngas stand alone as a fuel in a diesel engine in the study.

Sahoo et al. [32] investigated the second law analysis ofa single cylinder DI CI engine fuelled with syngas under adual fuel mode, in which diesel served as a pilot fuel [32].Theeffect of H

2/CO ratio on the dual fuel engine performance

and thermomechanical availability of the engine was studied.The imitation syngas was composed of H

2and CO mixed

in a gas mixer and was charged into the gas carburetor.The experiment was conducted at different load conditionsranging from 20 to 100% with a 20% interval. They reportedthat the syngas dual fuel had a better work availability athigher loads as compared to diesel fuelling. Besides, anincrease in the content of hydrogen in syngas improved thework availability of the dual fuelling. In a separate study, thesame researchers [14] investigated the effect of H

2/CO ratio

on the performance of a dual fuel engine under the same


test conditions.The performance parameters examined in thestudy [14] were brake thermal efficiency, diesel substitution,pressure profile,maximumcylinder pressure, and exhaust gastemperature. In addition, the resulting emissions like CO,NOx, and hydrocarbon (HC) were also investigated. ThesyngasH

2andCO compositionwere 50 : 50, 75 : 25, and 100%

in volume percentage. They observed that an increase in H2

in the syngas results in an increase in the brake thermal effi-ciency. The highest diesel replacement with syngas and max-imum in-cylinder pressure was observed at 80% load with100% H

2. On emissions, NOx was observed to increase with

H2content in syngas. As anticipated, the CO emission was

directly related to the CO content in syngas.TheHC emissionwas found to be minimum with 100% H

2[14].

Wagemakers and Leermakers [33] reviewed the effect ofdual fuelling of diesel and different gaseous fuels on perfor-mance and emission [33]. CNG, liquid petroleum gas (LPG),syngas, and hydrogen were some of the gaseous fuels con-sidered in their review. They reported that all gaseous fuels,when applied in diesel fuel combustion as dual fuel, coulddecrease soot emissions except for syngas. Reduction inNOx was reported when both CNG and LPG were used asprimary fuels. However, combustion of syngas and hydrogenincreased the NOx level as compared to diesel. Unburnedhydrocarbons and CO emissions increased with dual fuellingof all the gaseous fuels as compared to diesel alone. Withregard to the effect of these fuels on efficiency, hydrogenand LPG affected positively while syngas and CNG affectednegatively [33].

The performance of a dual fuel mode compression igni-tion engine fueled by syngas with a composition of 10% H

2,

25% CO, 4% CH4, 12% CO

2, and 49% N

2and diesel (as pilot

fuel) was compared with that of methane under the sameduel fuel arrangement [34]. For both two fuel mixtures, ashift from diffusion flame combustion to propagation flamecombustion was reported with reduction of the pilot dieselfuel. Overall, methane was shown to perform better ascompared to syngas in the duel fuelling mode for dieselsubstitution [34].

In summary, a complete replacement of diesel fuel withsyngas could not be possible. Besides, the performance ofsuch dual-fuelling of syngas and diesel was poorer as com-pared to dual-fuelling of CNG and diesel. Therefore, syngascannot be a reliable substitute to diesel fuel in CI engines.However, it can be used as a supplementary fuel to reducecost and emissions of NOx and particulate matter.

4.2. Syngas Combustion in Carbureted and Port InjectionSI Engines. The research and development of wood gasautomotive technology have taken place since the last 100years. However, there are still key technoeconomic barriersthat hinder its commercialization [35]. To date, researchin this category has been more or less a continuation ofthe World War II wood gas engine development. There aremany researches on both experimental and numerical inves-tigations of fuelling syngas in naturally aspirated carburetedand port injection engines. The research works can bebroadly classified into comparison of syngas and CNG [36]

and comparison of syngas and diesel [21] more specificallyto the study of overall energy balance of syngas fuelling,performance, and emission studies. The fuelling setup usedwas a direct coupling of gasificationwith a carburetion systemof the engine with a subsequent cleaning and cooling sys-tem integrated. Most of the studies used the conventionalcarburetor. However, Sridhar et al. [12, 15, 21] used a locallymanufactured carburetor in their investigation to addressthe high volume flow rate of gaseous fuel [12, 15, 21]. Theymodified a diesel engine into spark-ignition configuration toobtain a higher compression ratio SI engine suitable for syn-gas combustion. The latest research studies on utilization ofsyngas (including producer gas and medium calorific valuesyngas) in carbureted and port injection SI engine aresummarized here.

Sridhar [15] studied utilization of biomass derived pro-ducer gas in a high compression SI engine experimentally andnumerically/analytically [15]. In their experimental investi-gation, they optimized the compression ratio for maximumbrake power and efficiency by varying the compression ratiosto 11.5 : 1, 13.5 : 1, 14.5 : 1, and 17 : 1. Besides, they analyzed theoverall energy balance and the emission levels of CO andNO. The syngas used in their study was a producer gas withgas composition of 19 ± 1% H

2, 19 ± 1% CO, 2% CH

4,

12 ± 1% CO2, 2 ± 0.5% H

2O, and rest N

2and calorific value

of 4.65 ± 0.15MJ/Nm3, respectively. They observed a smoothcombustion process with a very low cyclic pressure variation.The producer gas experienced a short combustion durationprompting a retardation of ignition timing. With respectto power and efficiency, it was compared with diesel andreportedwith a power drop of 16% and 32%, respectively. Fur-thermore, a higher overall heat loss was reported for producergas. NO emission was dependent on the compression ratioand ignition timing.MaximumNO emission was observed atthe highest compression ratio and advanced ignition timing.On the contrary, minimumCO emission was observed at thehighest compression ratio.Themain attribute of the emissionresults was high temperature due to high compression ratio.This experimental work was also reported elsewhere [12, 21].Even though the study clarified themisconceptions about theautoignition of producer gas, it was restricted to naturallyaspirated carburetor engines.The study was also limited onlyto lower calorific value syngas (producer gas) [12, 15, 21].

Ahrenfeldt [37] studied the fuelling of biomass producergas on a combined heat and power (CHP) engine and its long-term effect [37]. Emission, performance, efficiency, and otheroperating parameters were investigated when producer gasproduced from three different gasification plants with theirlower heating values 5.5, 6, and 12.1MJ/Nm3 were engagedin the combined heat and power operations. Based on theperformance study, it was reported that producer gas is anexcellent fuel for lean burn application; its lean limit was closeto an excess air ratio (𝜆) of 3.00. There was no effect ofvariation of ignition timing on the power and efficiency.However, ignition timing was observed to affect the emissionlevel of NOx. The emission level of NOx was reported to below. On the other hand, CO emission was observed to bevery high due to the higher content of CO in the fuel. On


the combustion study, the coefficient of variation (COV) ofthe IMEP and mass fraction burn (MFB) remained constantfor the producer gas even when 𝜆 increased.

Mustafi et al. [38] investigated performance and emissionof power gas in a variable compression ratio SI engine andfurther compared it with that of gasoline and CNG. Thecomposition of power gas was mainly H

2, CO, and CO

2sim-

ilar to that of medium calorific value syngas produced fromthe gasification of solid fuels. However, the production ofthis fuel was through Aqua-fuel process. The molar ratio ofthe fuel investigated was 0.52, 0.44, and 0.04 for CO, H

2

and N2, respectively. The lower heating value of the gas was

15.3MJ/kg. The stoichiometric air-fuel ratio of the gas wasobserved to be 4.2 as compared to 14.6 and 15.5 for gasolineand CNG, respectively. A Ricardo single cylinder SI enginewith a variable compression ratio wasmodified to accompanya gas mixer, gas regulator, and needle valve setting to accom-modate the fuel-air blending before the cylinder. On theircomparison of power output of this gas at different compres-sion ratios, an improvement of 22% was reported by increas-ing the compression ratio from 8 : 1 to 11 : 1.The power outputof this gas, gasoline and CNG was compared at constantspeed of 1500 rev/min. It was reported that the brake torqueof power gas was 30% and 23% lower than that of gasoline,and CNG, respectively. The fuel consumption was alsocompared and power gas was requiring 2.7 and 3.4 timesmore than that of gasoline and CNG, respectively. However,consumption was not affected with the change in compres-sion ratio. Emissions of total hydrocarbon (THC) and CO ofpower gas were observed lower than for gasoline and CNG.However, CO

2and NOx emissions were higher than all

these fuels. These experimental results were compared withsimulation model and were found to be consistent at allconditions [38].

Papagiannakis et al. [39] have numerically modeled thecombustion process of a four-stroke, turbocharged, water-cooled, multicylinder SI GE Jenbacher 320 engine fuelledwith syngas [39].The fuel is a product of gasification of woodwith a volume percentage composition of 19% H

2, 29% CO,

6% CH4, 8% CO

2, and 38% N

2. The two-zone model

predicted in-cylinder pressure profile, heat release rate, nitricoxide (NO), and CO concentrations. The model results werevalidated by the experimental results from the same engineoperated at constant speed of 1500 rev/min at four conditionsof 40, 65, 85, and 100% of full load. Their observation mainlyfocused on the validation of the numerical model. Moreover,they discussed the combustion, performance, and emissioncharacteristics of syngas in comparison with CNG. However,the study was more focused on the numerical model vali-dation than the effect of fuel property on the combustion,performance, and emissions. Similar reports on syngas withtheir main intention on predictive model validation could befound elsewhere [40–42].

A small-scale naturally aspirated single cylinder SI enginewith compression ratio of 9.4 and 11.9 was used to test the per-formance of low-BTU gases produced from gasification and atwo-step pyrolysis/reforming process.The gas produced fromgasification was hydrogen rich with a lower calorific value

(LCV) of 3.83MJ/Nm3 while from the two-step pyrolysis wasmethane rich with LCV of 4.2MJ/Nm3.The carburetor in thefuelling system was replaced with a gas mixer to adjust theair-fuel ratio. They reported that the two fuels had registereda similar thermal efficiency compared to CNG. Besides, thehydrogen-rich gas produced from gasification was reportedwith a wider stable engine operation 𝜆 up to 2.00. Comparedto both CNG and the methane-rich pyrolysis gas, NOx andHC emissions were quite low with the hydrogen-rich gas.With the methane-rich gas, NOx was reported quite low too.There was no information about BSFC performance of thetwo fuels [43]. The study was limited to low-BTU gases only.

Shah et al. [44] have investigated the performance ofa naturally aspirated, single-cylinder, four-stroke, SI enginewith a capacity of 5.5 kW fuelled with syngas [44]. Thisfuel composition was 16.2–24.2% CO, 13–19.4% H

2, 1.2–6.4%

CH4, 9.3–13.8% CO

2, and balance N

2with a lower heating

value of 5.79MJ/Nm3. It was compressed to a pressure of15 bar and stored in LPG tank before fueled in the engine.The performance parameters used in this study were poweroutput, overall efficiency, and run duration of the engine bysyngas. Emissions such as CO, CO

2, HC, and NOx were also

investigated. The overall efficiency of both syngas and gaso-line was reported to be similar at their respective maximumpower output (1.392 kW for syngas and 2.451 kW for gaso-line). On the exhaust emissions side, CO was observed tobe 30–96% lower with syngas compared to gasoline at eachoperation. This was attributed to the higher carbon contentand rich operation in gasoline. For syngas, the CO emissionwas observed to increase with an increase in flow rate. TheCO2concentration was reported to be 33–167% higher with

syngas compared to gasoline operation.Thiswas attributed tothe CO

2presence in syngas and the conversion of CO content

in the fuel upon combustion. The CO2concentration was

observed to increase with an increase in flow rate of syngas.Thehydrocarbon concentration of exhaust emission of syngaswas less than 40 ppm in all operations.This negligible contentwas attributed to the limited presence of HC in syngas. NOxemission in syngas operation was reported to be 54–94%lower compared to gasoline operation. This was attributed tolower cylinder temperature as a result of lower heating valueof syngas. The NOx concentration versus flow rate profilewas similar to that of power output curve. In this study,comparison was made only to gasoline. CNG was not con-sidered. However, comparison of gaseous fuel with liquidfuel in internal combustion has its own constraints as perSridhar andYarasu [45]. Combustion characteristics were notinvestigated in the study. Besides, effects of ignition timingand air-fuel ratio on the combustion, performance, andemissions were not properly addressed.

Bika [46] studied varied ratios of H2/CO syngas in a port

injection SI engine and variable compression (4 : 1–18 : 1) fortheir combustion characteristics and knock limit [46]. Thefuel was injected at 4 cms from the intake port. The fuelsinvestigated are pure H

2, 75% H

2/25% CO, and 50% H

2/50%

CO. The study was limited to 𝜙 = 0.6–0.8 and compressionratios of 6 : 1 to 10 : 1. It was reported that an increasein percentage of CO increased the knock limit of syngas.


The study also indicated that the increase in CO percentagehas advanced the ignition timing of MBT. Maximum heatrelease rate was observed with pure hydrogen. The peakpressure was, however, observed to be more influenced bythe compression ratio rather than by the CO percentage. TheMFB was also observed broader with an increase with COpercentage.The overall conclusion of the study was that therewas an increase in combustion duration with an increase inCO percentage. A maximum indicated thermal efficiency of32% was reported with 50% H

2/50% CO at 𝜙 = 0.6 and com-

pression ratio of 10 : 1. The study was limited to combustiononly. Performance and emissions of these fuels were notinvestigated.

In summary, reduction of torque was reported in most ofthe researches with syngas as compared to their fossil-basedcounterparts. This was more pronounced with the lowercolorific value syngases (producer gases) as it demands highervolume of gas to produce equal amount of power producedfrom higher calorific value gases such as CNG and gasoline.Besides other combustion parameters, the main attribute tosuch power reduction was the volumetric efficiency penalty.An appreciable amount of air gets displaced by the lowercalorific value syngas.

5. Current Engine Technologies

Over the years, ICE has passed through a lot of technologicaladvancements. The engine fuelling system was among otherparts which had huge attention. Early engines were fueledwith a surface carburetion system where air passes over astored fuel picking some from the surface [47]. Throughthe inspiration of this technology, other carburetion systemscame to light over the years. In 1875, Siegfried Marcusinvented a rotary-brush atomizer that operates through drop-ping of fuel in the air suction as a result of brush rotation overthe fuel storage surface. Even though this technology wasbetter at atomizing the fuel, the fuel entered into the com-bustion chamber without evaporation.This shortcoming wasaddressed through the invention of wick carburetor by Fred-erick William Lanchester in 1896. A wick was extended fromfuel storage chamber to the air passage chamber. As a result,fuel passed from the bottom of the wick into the upperchamber where it evaporated. The incoming air in the upperchamber mixed with the evaporated fuel and sucked into thecombustion chamber [48].The introduction of float type car-buretors by Wilhelm Maybach and Gottlieb Daimler as citedin Barach [48].

The float type carburetor, also called simply carburetor,was dominant technology over 90 years up to 1980s witha continuous upgrading over the years. This technologybecame very complex as it had to include many circuits toaccommodate the demands of high efficiency and low emis-sions. Even though it is still the cheapest fuelling technology,it has been phased out and replaced with other technologiesdue to its inefficiency and lack of attaining the current emis-sion standards. However, it is still operational in countrieswhere emission regulation is weak [49].

After the era of carburetor, fuel injection systems becamethe primary technology to deliver fuel into the chamber. Inthis technology, atomization of the fuel is done by forcing thefuel through a narrow nozzle with the help of high pumpingpressure. The early fuel injection system was a throttlebody fuel injection system where an electronically controlledinjection system was added to the throttle body. This designwas later modified into port injection system where everycylinder was equipped with fuel injectors that spray fuel nearthe inlet valve. Even though the multipoint/port injection isby far better technology than the carburetor in fuel metering,it still needs more time to completely mix fuel and air beforeentering the combustion chamber [50].This further impingesnegatively on the fuel efficiency of the engine. Such limitationhas prompted for the adaptation of DI technology from dieselengines. In the DI SI engine, high-pressure fuel is deliveredinto a common rail, from where it is injected direct intothe cylinder via fuel injectors. Due to the high pressure andinjector nozzle interaction, the fuel is atomized in the cylinderwith a varied degree of penetration depending on the angle ofthe injectors.This technology is fuel efficient, allowing precisecontrol system that puts century-old ICE still in a betterposition compared to hybrid and electric vehicles.

With the emergence of DI application in SI engines, leancombustion strategy has become a means for the reductionof greenhouse gas emissions and an increase in thermalefficiency [30, 51–53]. This strategy is mainly accompaniedwith fuel stratification so that variable air-fuel ratio occurredaround the combustion chamber. The stratification providesa relatively rich mixture near the igniter and a uniformlymixed ultralean mixture all over the cylinder [30]. Engineperformance reduction due to volumetric efficiency drop canalso be overcomeby injecting the fuel very late after inlet valvecloses (IVC). However, this may lead to insufficient time forfuel-air mixing and slow combustion rate. For the fast burn-ing type fuels, this is the type of fuel injection strategy thathas been adopted and it has attracted much attention thesedays.

CNG DI had been under intensified research and devel-opment since the 1970s. Previous research and developmentof natural gas vehicles (NGV) was focusing on modificationof the existing petrol engines. However, currently there isan increasing trend on the application of original equipmentmanufacturer (OEM) vehicles for natural gas vehicle (NGV)with DI technology getting mature and the demand ofNGV increasing [54]. Currently, the global NGV vehicle isestimated at 20.21 million with 21,400 refueling stations [55].However, syngas-fuelled DI engine has not been investigatedbefore.

6. Potential of Syngas in CurrentEngine Technologies

The success of syngas reported in old ICE needs to beinvestigated for the reinstatement of the fuel in the currentengine technology. Syngas produced from gasification ofbiomass lacks consistency in the percentage composition ofconstituent gases [21]. There are many varieties of syngas


Table 1: Supplied syngas composition.

Component Syn1 (V%) Syn2 (V%) Syn3 (V%)Hydrogen 50 40 19.16Carbon monoxide 50 40 29.60Methane 0 20 5.27Carbon dioxide 0 0 5.41Nitrogen 0 0 40.56

products stated in the literature. The quality of syngasproduced from gasification is mainly dependent on thegasifying agent used in the process. A low calorific valuesyngas (producer gas) of H

2, CO, CH

4, CO2, and N

2of varied

proportion as constituent gases are generated if air is usedas gasifying agent. If steam or oxygen is used instead ofair, a medium calorific value syngas with H

2, CO, and CH

4

of varied proportions as constituent gases are produced[2]. In order to understand the suitability of syngas in thecurrent engine technologies, representative of the abovemen-tioned category of syngases, various compositions of syngasesshould be investigated for their combustion characteristics.Table 1 shows three different syngases selected from the lowerand medium calorific value syngases for a case study.

Detailed knowledge of the properties of fuels helps selec-tion of appropriate operating parameters for an internal com-bustion engines. In this section, properties of three differenttypes of syngases were investigated for their properties. CNGand hydrogen twomajor gaseous fuels with their combustionand performance in the current engine technologies werewidely investigated. Their potential and foreseeable chal-lenges have been studied by different researchers [30, 56–60].The combustion of CNG is less complete resulting in lowerperformance coupled with higher CO and THC emissions.They are attributed to the lower laminar flame velocity,narrow combustible range, high ignition energy requirement,and higher self-ignition temperature [30]. Even with suchshortcomings, this fuel is currently serving its purpose asstated in Section 5. On the other hand, hydrogen has greateradvantage with the greenhouse gas emission due to its cleancombustion. However, usage of this fuel is hindered due toits high production cost, difficulty in its storage, high flamespeed, and high flame temperature leading to unstable com-bustion and knock [58].The properties of these syngases werecompared with those of CNG and hydrogen to assess thesuitability of this fuel in the current engine technologies.Table 2 shows the detailed comparison of properties of threesyngases, CNG, and hydrogen.

The fuel properties for the three syngases listed in Table 2are mostly calculated based on their species except for thelaminar flame velocity and autoignition temperature. Thehydrogen-to-carbon ratio (H/C) is the main factor in theproduction of the greenhouse gas emissions from the com-bustion of fuels [30]. An increase in H/C leads to reducedproduction of CO

2and increased production of H

2O in the

combustion products. To this end, hydrogen is free ofgreenhouse gas emissions. H/C of gasoline, CNG, Syn1, Syn2,

and Syn3 are calculated to be 1.85, 4, 2, 2.67, and 1.45, respec-tively. Syn1 and Syn2 have better greenhouse gas emissionperformance as compared to gasoline. Besides, syngases areconsidered to be carbon neutral fuels especially if they areproduced frombiomass and solidwaste gasification. Syngasesare also oxygenated fuels resulting in a clean burning and animproved power and efficiency.

Syngases have lower calorific value compared to CNG.However, all syngases have better stoichiometric mixtureenergy density as compared to CNG in an air aspirating(direct-injection) engines as shown in Table 2. The energyobtained from the combustion chamber is more influencedby the mixture energy density than by the lower calorificvalue of the fuel [13]. Therefore, the performance of a direct-injection syngas powered engine is expected to be improvedas compared to the naturally aspirated carbureted and portinjection engines.

Syngases have also wider flammability range as comparedto CNG.This property is responsible for COV of the IMEP ofthe combustion of the fuel. It is ameasure of the extent ofmis-firing of the combustion. Therefore, syngases are expected tohave lower COV.Additionally, syngases have higher autoigni-tion temperature as compared to hydrogen and CNG. Thiswill make them favorable for high compression engine appli-cation with no incident of knock. Similar observation wasreported by Sridhar et al. [21]. The moderate laminar flamevelocity of syngases improves the slow combustion reportedwith CNG and the unstable combustion reported withhydrogen.

Syngases, especially the medium calorific value syngases,have an adiabatic flame temperature close to that of hydrogenleading to higher NOx emissions. Moreover, syngases haveextremely low stoichiometric air-fuel ratio as compared toCNGandH

2.This could result in high brake specific fuel con-

sumption (BSFC). These fuels cannot be operated near stoi-chiometry as it is impossible to completely inject the amountof fuel that makes stoichiometric air-fuel ratio especially forfuels similar to Syn3. A lean charge direct-injection needs tobe adapted to avoid the high NOx emissions and the higherBSFC of such fuels. However, the mixture energy densityof a lean homogenous mixture of syngases will be very lowleading to misfiring and demanding higher ignition energy.A charge stratification strategy can be followed to reduce thecombustion misfiring. Such fuel stratification can only beattained through late injection of the charge after the inletvalve closes in the direct-injection spark-ignition engines.Nevertheless, late injection of syngases with low andmediumcalorific value leads to limitation of injection durationthereby limiting power output. Only the medium calorificvalue syngases (similar to Syn1 and Syn2) can deliver com-parable power and torque output to their CNG counterparts.The lower calorific value syngases (similar to Syn3) may befeasible in older engines such as the naturally aspirated carbu-reted and port injection engines. However, their demand forlonger injection duration in direct-injection engines and theirassociated lower mixture energy density at lean operationmakes them less favorable in current engine technology.


Table 2: Properties of different syngases and their comparison to CNG and H2.

Properties Syngases CNG H2Syn1 Syn2 Syn3Composition, weight %

Carbon 40.0 47.37 21.15 75.0 0.0Hydrogen 6.67 10.53 2.56 25.0 100Oxygen 53.3 42.1 28.3 0.0 0.0Nitrogen 0.0 0.0 48.5 0.0 0.0

Molecular weight (g/mol) 15.0 15.2 23.2 16.04 2.02Density at 0∘C and 1 atm (kg/m3) 0.67 0.68 1.04 0.75 0.09Specific gravity at 0∘C and 1 atm 0.52 0.53 0.8 0.58 0.07Stoichiometric air-fuel ratio

Molar basis 2.38 3.81 1.66 9.7 2.38Mass basis 4.58 7.23 2.07 17.2 34.3

Stoichiometric volume occupation in cylinder, % 29.6 20.8 37.6 9.35 29.6Lower calorific value

MJ/Nm3 11.65 16.48 7.67 38.0 10.7MJ/kg 17.54 24.4 7.47 47.1 120.2

Stoichiometric Mixture Energy density (MJ/Nm3)Mixture aspirated 3.3 3.25 2.73 2.9 [13] 3.2 [13]Air Aspirated 4.45 3.92 4.19 3.60 [13] 4.54 [13]

Flammability limit, % vol. of fuel in airLower 6.06 5.8 13.4 5.3 4.0Higher 74.2 41.4 57.9 15.0 74.2

Laminar flame velocity (cm/s) 180 [14] N/A 50 [15] 30 210Adiabatic flame temperature, K 2385 2400 2200 2220 2383Autoignition temperature, K 873–923 873–923 898 813 [16] 858 [16]

7. Conclusions

(i) The direct-injection fuelling system technology andhigh compression ratio of the latest spark-ignitionengines, improvement in conversion efficiency, andadvancement in the cleaning process of gasification,the introduction of syngas storage, and thereby sepa-ration of gas production and power generation are themotivating factors for syngas to be a fuel in currentengine technologies.

(ii) Stratified lean charge combustion is an effective wayof powering syngas in the current engine technologyto address the problems of stoichiometric chargeapplication caused due to very small stoichiometricair-fuel ratio. However, care should be taken tothe limitation on the power caused due to limitedinjection duration. Further investigation of the opti-mization of injection timing, fuel composition, air-fuel ratio, and ignition advance needs to be done forbetter performance and emissions.

(iii) The problem associated with the higher BSFC ofsyngases need to be addressedmainly on the design ofstorage systems.The calorific value of CNG is three toten times that of syngases. This has huge implicationon the storage system in order to have the samedriving range to CNG counterpart.

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper.

Acknowledgments

This work was supported by the Centre for Automo-tive Research and Electric Mobility (CAREM), UniversitiTeknologi PETRONA

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