Study of Cyclic Variability in Diesel-Hydrogen Dual Fuel Engine Combustion

Transcription

1 Iteratioal Joural of Mechaical & Mechatroics Egieerig IJMME-IJENS Vol:2 No:04 52 Study of Cyclic Variability i Diesel-Hydroge Dual Fuel Egie Combustio Widodo Budi. Satoso, Rosli Abu. Bakar, Sugeg. Ariyoo, ad Nur. Cholis Abstract Amog the alterative fuels, hydroge shows great potetial i the ear future. I the preset study, the cyclic variability of a diesel egie fueled with hydroge ad igited by diesel spray was studied. To ivestigate the combustio characteristics of this dual fuel egie, a sigle cylider diesel research egie was coverted to utilize hydroge as fuel. Hydroge was itroduced to the itake maifold usig a mixer before eterig the combustio chamber. The egie was ru at a costat speed of 2000 rpm ad variable loads. At each load step the flow rate of hydroge was varied. A egie idicatig system was used to measure ad record the cylider pressure up to 60 cosecutive combustio cycles. The combustio data for each operatig coditios were aalyzed for the maximum cylider pressure ad idicated mea effective pressure (IMEP). The cycle-by-cycle variatio is expressed as the mea value, stadard deviatio, coefficiet of variatio of these two parameters. It is foud that cyclic variability is reduced at higher egie load operatio Idex Term diesel, hydroge, dual fuel, cyclic variability. I. INTRODUCTION Developmet of ew eergy resources has become a importat ageda i relatio to eergy security ad evirometal aspects. Efforts have bee delivered to utilize those eergy resources strategically, icludig itesificatio, diversificatio, ad coservatio. Alterative fuels such as alcohol, gas (CNG, LPG, biogas, producer gas, ad hydroge) have bee studied itesively. Amog the alterative fuels, hydroge shows great potetial i the ear future. The advatages of usig hydroge as fuel for iteral Widodo Budi. Satoso is PhD Studet at Uiversiti Malaysia Pahag, Peka, Pahag, Malaysia wbsatoso@gmail.com Rosli. Abu Bakar is Professor at Uiversiti Malaysia Pahag, Peka, Pahag, Malaysia rosli@ump.edu.my Sugeg. Ariyoo, is Seior Lecturer at Politekik Negeri Semarag, Semarag, Idoesia s.ariyoo@gmail.com Nur. Cholis is Master Studet at Uiversiti Malaysia Pahag, Peka, Pahag, Malaysia r.chls@gmail.com combustio egie is amogst other a log-term reewable ad less pollutig fuel, o-toxic, odorless, ad has wide rage flammability []. Hydroge caot be used directly i a diesel egie because its autoigitio temperature is higher tha that of diesel fuel. Oe alterative method is to use hydroge i erichmet or iductio. Hydroge is mixed with air or ijected i the itake maifold before eterig combustio chamber. Small amout of diesel fuel, called pilot fuel, is ijected to promote igitio. This dual fuel egie, or is ofte called diesel pilot-igited hydroge egie has the advatage to switch back to covetioal diesel operatio i case of shortfall i gas supply. These beefits lead researchers worldwide ivestigated the utilizatio of gas icludig hydroge as fuel for diesel egie It is obvious that cycle-by-cycle variatio occurred i spark igitio iteral combustio egie. Cyclic variatios i the combustio process are caused by variatios of mixture motio withi the cylider, variatios i the amouts of air ad fuel fed to the cylider each cycle, ad variatios i the mixig of fresh mixture ad residual gases withi the cylider each cycle [2]. I cotrast to spark igitio egies, the combustio process of compressio igitio egie is regarded as beig stable. However, more detailed ivestigatios o combustio process reveal cyclic variability i diesel egie fueled with pure diesel or diesel/biodiesel bledig [3]-[6]. There have bee may studies cocerig cycle-by-cycle variatio ad combustio stability of spark igitio egies fueled with gaseous fuels, either sigle gas or bleded gas [7]- [9]. The characteristics of mixture formatio, igitio, ad combustio process of the fuel-air mixture that greatly iflueces the cycle variatio are well uderstood. However, i the dual fuel egie i which the diesel fuel igites the hydroge-air mixture, the igitio characteristics of the gaseous fuel are ot well uderstood. I additio to the cause of cyclic variatios exist i diesel egie, dual fuel egies appear to be more proe to cyclic variability i combustio oise due to existece of gaseous fuel with compressed air [0]. Therefore, it was cosidered ecessary to study the cycle variatio of the diesel-hydroge dual fuel egie that was ot covered before. The purpose is to ivestigate the effect of hydroge additio ad egie operatig coditio o cycle

2 Iteratioal Joural of Mechaical & Mechatroics Egieerig IJMME-IJENS Vol:2 No:04 53 variatio of the dual fuel egie. II. METHODOLOGY To ivestigate the combustio characteristics of this dual fuel egie, a sigle cylider diesel egie with the specificatios as show i Table was coverted to utilize hydroge as fuel. Hydroge was itroduced to the itake maifold by a mixer before eterig the combustio chamber. It was supplied from a high-pressure cylider (50 bar) ad the reduced to a pressure of.5 bar usig a pressure regulator. Hydroge was passed through a fie cotrol valve to adjust the flow rate ad the through a gas flow meter that metered the flow of hydroge. The hydroge was passed through a flash back arrestor (flame arrestor) prevetig reverse flow of hydroge ito the system. Next, the hydroge was allowed to pass through a flame trap, used to suppress flash-back ito the itake maifold. TABLE I ENGINE SPECIFICATIONS Egie Type Sigle cylider air-cooled DI diesel egie Rated power rpm Maximum torque rpm Bore x stroke 00 mm x 85 mm Corod legth 36.5 mm Swept volume liter Compressio ratio 20.5: The egie was coupled to a SCHENCK eddy-curret dyamometer with a rated power of 70 kw. Egie torque ad speed were measured by the dyamometer. I-cylider pressure was measured usig a Kistler water-cooled piezo electric pressure trasducer ad was sampled every degree crak agle. Start of ijectio ad ijectio duratio were measured by a eedle lift sesor. Pressure traces ad eedle lift data were recorded ad aalyzed usig a egie idicatig system. Diesel fuel cosumptio was measured usig gravimetric fuel balace AVL 733S. Hot film aemometer was used to measure air cosumptio. The egie was started with diesel fuel at 2000 rpm ad 5 Nm load. After allowig the egie to reach the steady state coditios, the followig parameters were measured ad recorded: fuel (diesel ad hydroge) cosumptio, air cosumptio, exhaust gas temperature, eedle lift, ad cylider pressure. Hydroge was itroduced at the flow rate of 2.4 l/miute. Egie speed was kept costat by adjustig the ijectio pump lever positio. The above parameters were measured ad recorded agai. This procedure was repeated for differet loads ad hydroge flow rates. A egie idicatig system was used to measure ad record the cylider pressure up to 60 cosecutive combustio cycles. The combustio data for each operatig coditios were aalyzed for the maximum cylider pressure ad idicated mea effective pressure (IMEP). The cycle-by-cycle variatio is expressed as the mea value, stadard deviatio, ad coefficiet of variatio of these two parameters. Statistical calculatio was coducted usig a Excel spreadsheet program. Mea value, stadard deviatio, ad coefficiet of variatio of maximum cylider pressure (P max ) are defied respectively as follows: =, i () σ P max COV = i= 2 (, i ) (2) σ = (3) P i= max Similarly, these three equatios were applied for statistical calculatio of IMEP. III. RESULTS AND DISCUSSION I this ivestigatio, the combustio characteristics of a DI diesel egie are studied by usig hydroge erichmet. The percetage of diesel eergy at each load coditio whe hydroge was itroduced is depicted i Fig. 2. As expected, part of diesel fuel was replaced by hydroge. Hydroge was itroduced at the same flow rate icremet for each load coditio. Hece, at the same hydroge flow rate, the percetage of diesel fuel at a higher load is bigger.. Hydroge surge tak 7. Gravimetric fuel meter 2. Barometer 8. Crak agle ecoder 3. Digital gas flow meter 9. Sigal coditioig 4. Flash back arrestor 0. Egie idicatig system 5. Flame trap. PC 6. Hot film air flow meter Fig.. Schematic of the experimetal setup The egie was ru at a costat speed of 2000 rpm ad variable loads. At each load the hydroge was itroduced at the flow rate of 2.4, 28.5, 36.2, 42.8, ad 49.6 liter/miute. Fig. 2. Diesel eergy replacemet by hydroge additio The respose of diesel ijector whe hydroge was itroduced at 2000 rpm ad 5 Nm is show i Fig. 3. The reductio of diesel fuel was represeted by the ijector eedle lift over the crak agle. Start of diesel ijectio is almost the same for all

3 Iteratioal Joural of Mechaical & Mechatroics Egieerig IJMME-IJENS Vol:2 No:04 54 coditio. Diesel reductio is show by a smaller distace of eedle lift ad the earlier ed of ijectio. oted that the cylider peak pressures resulted from dual fuel combustio are higher tha that of diesel combustio. Previous study [] showed that i this operatig coditio, the percetage of diesel fuel is more tha 30% ad idicated efficiecy is slightly icreased at higher hydroge flow rate. This portio of diesel fuel is sufficiet to produce efficiet dual fuel combustio. Igitio delay is a little bit loger ad most combustio is i the form of premixed combustio. Fig. 3. Needle lift at 2000 rpm, 5 Nm (a) (a) (b) Fig. 4. Cylider pressure variatio i diesel (a), ad dual fuel egie (b) at 5 Nm load Fig. 4 shows the cylider pressure variatio for 36 cosecutive cycles i diesel ad dual fuel operatio at egie load of 5 Nm. Hydroge was added at 49.6 l/mi for dual fuel operatio. More hydroge erichmet resulted i lower cylider pressure. The average of maximum cylider pressure for 60 cycles i diesel operatio was 7.0 bar, compared to that of bar i dual fuel operatio. The combustio process was promoted by the autoigitio of diesel fuel. I such a lower load, diesel percetage o eergy basis reduced sigificatly with a icrease i hydroge. The amout of diesel fuel to igite the premixig of hydroge with air was reduced ad resulted i a late start of combustio ad the combustio istability. I cotrast to low load operatio, the cyclic variability at high load operatio was ot so obvious, as depicted i Fig. 5. It is (b) Fig. 5. Cylider pressure variatio i diesel (a), ad dual fuel egie (b) at 20 Nm load Fig. 6 depicts IMEP variatio whe hydroge was itroduced at the flow rate of 2.4 l/mi ad 49.6 l/mi. The egie operated at 5 Nm load ad 2000 rpm. There is a sigificat variability betwee these two cases but the mea values are almost the same. The availability of diesel fuel eeded to igite the premixig of hydroge with air resulted i combustio istability as discussed above. O eergy basis, the percetage of diesel fuel at 2.4 l/mi hydroge erichmet was aroud 46%. A further icrease i hydroge erichmet at 49.6 l/mi reduced the percetage of diesel fuel to 3%. This portio of diesel is ot sufficiet to produce a efficiet combustio.

4 Iteratioal Joural of Mechaical & Mechatroics Egieerig IJMME-IJENS Vol:2 No:04 55 Fig. 6. IMEP variatio due to hydroge additio at 5 Nm load Cyclic variability of IMEP whe the egie is operated at higher load is show i Fig. 7. Hydroge additio slightly icreased the average value of IMEP from 8.69 to 9.8 bar due to the icrease of the cylider peak pressure. The amout heat released is icreased with the icrease of hydroge additio due to the better idicated efficiecy. It is oted that cyclic variability was slightly reduced. Hydroge additio reduced the percetage of diesel fuel, but it is sufficiet to produce the efficiet combustio. Fig. 8. Coefficiet of Variatio of IMEP at variable load ad hydroge flow rate CONCLUSIONS This experimetal work presets a statistical aalysis of the cycle-by-cycle variatio of a sigle cylider diesel-hydroge dual fuel egie. Cyclic variability teds to icrease with the icrease of hydroge erichmet. It is obvious especially at low load ad hydroge erichmet more tha 30 l/mi. It is foud that cyclic variability is reduced at higher egie load operatio. This is due to the icreasig the diesel portio that promote the autoigitio ad resulted i stable combustio from oe cycle to aother cycle. The ivestigatio ca be exteded to wider egie operatio rages. The relatios of cyclic variability o egie oise ad emissios ca be ivestigated for further research. ACKNOWLEDGMENT The authors wish to thak Uiversiti Malaysia Pahag for supportig this research uder GRS Fully support from Iteral Combustio Egie Laboratory LIPI by providig the experimet facilities are grateful ackowledged. Fig. 7. IMEP variatio due to hydroge additio at 20 Nm load Fig. 8 depicts the coefficiet of variatio (COV) of idicated mea effective pressure (IMEP) for all loads applied ad hydroge erichmet. As stated above, the cyclic variability teds to icrease with a icrease i hydroge additio at low load. It is oted that combustio stability was achieved at higher loads. The combustio process was promoted by the autoigitio of diesel fuel. At higher load ad the same hydroge flow rate, diesel percetage o eergy basis icreased. The amout of diesel fuel to igite the premixig of hydroge with air was icreased ad resulted i better combustio stability. REFERENCES [] J. Fulto, F. Lych, ad R. Marmora, "Hydroge for reducig emissios from alterative fuel vehicle," SAE Techical Paper, vol. No. 9383, 993. [2] J. B. Heywood, Iteral Combustio Egie Fudametals. Sigapore: McGraw-Hill Iteratioal Editios, 988. [3] A. K. Se, R. Logwic, G. Litak, ad K. Górski, "Aalysis of cycle-tocycle pressure oscillatios i a diesel egie," Mechaical Systems ad Sigal Processig, vol. 22, pp , [4] A. B. V. Barboza, N. Yagesh Sharma, ad C. V. Sudhir, "Cyclic combustio studies of a CI egie operatig o jatropha B20 fuel," i It. Cof. o Mechaical ad Electrical Techology, Sigapore, 200, pp [5] K. Bizo, G. Cotiillo, K. C. Leister, E. Macaruso, ad B. M. Vaglieco, "POD-based aalysis of cycle-to-cycle variatios i a optically accessible diesel egie," Proceedigs of the Combustio Istitute, vol. 32, pp , 2009.

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