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Effect of direct water injection during compression stroke on thermal efficiency optimization of common rail diesel engine
Available online at www.sciencedirect.com
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Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Available Energy Energy Procedia Procedia 00 00 (2017) (2017) 000–000 000–000
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Energy Procedia 142 Energy Procedia 00(2017) (2017)1251–1258 000–000 www.elsevier.com/locate/procedia
9th International Conference on Applied Energy, ICAE2017, 21-24 August 2017, Cardiff, UK
Effect of direct water injection during compression stroke on 15th International Symposium on District Heating and Cooling thermal The efficiency optimization of common rail diesel engine a a demand-outdoor Assessing theKang feasibility of ausing theChao heat Zhehao Zhanga, Zhe , Lang Jiang , Yuedong , Jun Denga, Zongjie Hua, temperature function for a long-term Liguang Lia, Zhijundistrict Wua,* heat demand forecast a aSchool
School of of Automotive Automotive Studies Studies Tongji Tongji University, University, Shanghai Shanghai and and 201804, 201804, China China
I. Andrića,b,c*, A. Pinaa, P. Ferrãoa, J. Fournierb., B. Lacarrièrec, O. Le Correc a
IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal Abstract b Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France c
Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France
The increasingly strict emissions regulations put forward higher request of NOx emissions control to diesel engines. Water addition is considered to be an effective way to reduce NOx emissions. However, most studies around the world concerned mainly about the effect of water addition on NOx reduction. The effect of water addition on diesel engine efficiency was not paid asAbstract much attention as on emissions. A series of experiments were carried out on test bench based on a two cylinder diesel engine with the modifications of adding common rail system and direct water injection system. The effects of direct water injection on diesel combustion and indicated thermal addressed efficiency inoptimization studied theeffective mechanism of thermal efficiency District heating networks are commonly the literaturewere as one of theand most solutions for decreasing the improvement due to compression stroke water injection was revealed. The influences of water injection duration and water greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat injection timing arechanged also studied. showed compression stroke directheat water injection is beneficial to decrease, thermal sales. Due to the climateResults conditions and that, building renovation policies, demand in the future could efficiency. test conditions up to 4.08% indicated thermal efficiency enhancement is achieved. The thermal efficiency prolongingUnder the investment return period. enhancement is mainly the reduction of negative stroke’s work due to the heat absorption ofdemand water The main scope of this attributed paper is totoassess the feasibility of usingcompression the heat demand – outdoor temperature function for heat evaporation and the increment of positive power stroke’s work due to the addition of working fluid. For small water injection forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 duration, injection timing in the compression leads Three to higher thermal efficiency, injection at and late stage the buildingsearlier that vary in both construction period andstroke typology. weather scenarios (low,while medium, high) three in district compression stroke is were more developed suitable for(shallow, larger water addition quantity. at first until reaches its peak renovation scenarios intermediate, deep). ToThermal estimateefficiency the error, rises obtained heat demand values were value, and with thenresults drops from witha dynamic increasingheat water injection increasing water by injection duration deteriorates compared demand model,duration. previouslyFurther developed and validated the authors. combustion and has negative impact on thermal efficiency. The highest thermal efficiency enhancement is achieved 0.4ms The results showed that when only weather change is considered, the margin of error could be acceptable for someunder applications water injection duration and 180°CA BTDC water timing condition. (the error in annual demand was lower than 20%injection for all weather scenarios considered). However, after introducing renovation ©scenarios, 2017 Thethe Authors. Published by Elsevier Ltd. (depending on the weather and renovation scenarios combination considered). error value increased up to 59.5% © 2017 The Authors. Published by Elsevier Ltd. committee of the 9th International Conference on Applied Energy. Peer-review under responsibility of the scientific The value of slope coefficient of increased on average within the 9th range of 3.8% up to 8% per corresponds to the Peer-review under responsibility the scientific committee of the International Conference ondecade, Appliedthat Energy. decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and Keywords: Direct water Diesel engine, Thermal efficiency Keywords: Direct water injection, injection, DieselOn engine, Compression stroke, Thermal efficiency renovation scenarios considered). the Compression other hand, stroke, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and ** Corresponding Corresponding author. author. Tel.: Tel.: +86-139-1674-7031 +86-139-1674-7031 Cooling. E-mail E-mail address: address: [email protected] [email protected]
Keywords: Heat demand; Forecast; Climate change 1876-6102 © 1876-6102 © 2017 2017 The The Authors. Authors. Published Published by by Elsevier Elsevier Ltd. Ltd. Peer-review Peer-review under under responsibility responsibility of of the the scientific scientific committee committee of of the the 9th 9th International International Conference Conference on on Applied Applied Energy. Energy.
1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling.
1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 9th International Conference on Applied Energy. 10.1016/j.egypro.2017.12.514
Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
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1. Introduction Supplying water into the cylinder is considered to be one of the most promising internal measures of diesel engines to reduce NOx emissions. Generally, fuel water emulsion, intake water injection and direct water injection are the three main approaches utilized to provide water into combustion chamber. In water fuel emulsion fuel and specific ratio of water are mixed by a trace content of surfactant. By using water fuel emulsion, NOx, PM and soot emissions are reduced simultaneously[1]. The micro- explosion phenomena in the emulsion spray induced by volatility differences between fuel and water improve the air entrainment, which lead to better atomization[2,3]. D.T.Hountalas et al. utilized a multi-zone combustion model to compare and evaluate EGR, intake water injection and fuel water emulsion in NOx reduction and found out that, at the same NOx reduction level, only soot emissions of fuel water emulsion decreased[4]. The drawback of water fuel emulsion is the restrict of fixed water to fuel ratio since there are different best water to fuel ratios for different engine operating conditions[3,5]. Intake water injection is the easiest method to introduce water to cylinder, which needs the minimal modification to the existing engine structure. S. Brusca and R. Lanzafame investigated the effect of water injection on a CFR Cetane Engine with water to fuel mass ratio varying from 0 to 1.5 and reported that NOx concentration in exhaust gas decreases as water to fuel mass ratio increases. Maximum NOx reduction up to 40% was achieved when W/F ratio was 1.5[6]. The effect of intake manifold water injection of a CI engine fueled with biodiesel was studied by B.Tesfa et al. Results showed that water injection does not show clear effect on BSFC and thermal efficiency at intermediate and higher engine loads, but has a negative impact of maximum 4% reduction of BSFC at low engine loads. They also found out that water injection leaded to NOx reduction by up to 50% over entire operating range[7]. One of the biggest advantages of direct water injection is the variable suitable water to fuel ratio depending on different engine operating conditions. Arto Sarvi et al. investigated the effect of direct water injection (DWI) on the emissions on large-scale medium-speed turbo-charged diesel engines and found out that DWI results in significant NOx and slight HC emissions reduction and slight soot and PM emissions increment[8]. Rudolf H. Stanglmaier et al. developed a diesel water coinjection system and mounted it on a production Volvo D-12 heavy duty engine. A conclusion is drawn that fuel water coinjection is effective for steady state NOx, HC, CO and smoke emissions[9]. The effect of water injection on combustion can be wildly divided into three parts: thermal effects, chemical effects and dilution effects [10]. In regard to thermal effects, evaporation cooling of water in air charge increases the density and air mass of intake charge. Water vapor in the cylinder also causes higher specific heat capacity of the intake charge. Both give rise to lower combustion temperatures and lower NOx emissions[6,10,11]. In cylinder water dilution effect refers to the reduction of concentration of oxygen per unit volume or mass of charge caused by inert medium introduction[12,13]. The chemical effect is that supplied water decreases the concentration of atomic oxygen and suppresses NO formation reactions[14,15]. Most researches focused on emissions and a widely accepted conclusion is that the introduction of water has great benefits on NOx reduction with little or slight effect on thermal efficiency. This study concentrated on engine thermal efficiency and revealed the mechanism of efficiency enhancement contributed by water injection. 2. Experimental Setup The test is conducted on a common rail diesel engine retrofitted from a two cylinder mechanical pump diesel engine. Engine specifications are shown in Table 1. Table 1. Engine Specifications. Type
Value
Type
Value
Displaced volume
808ml
Number of Valves
2
Stroke
114mm
Exhaust Valve Open
225°BTDC
Bore
95mm
Exhaust Valve Close
15°ATDC
Connecting Rod
255mm
Inlet Valve Open
15°BTDC
Compression Ratio
17:1
Inlet Valve Close
225°ATDC
Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
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The schematic diagram of diesel engine direct water injection test bench is shown in Fig 1. A fuel supply system provided from 200bar to 1600bar high pressure diesel. A Bosch diesel injector was utilized to inject diesel directly into one test cylinder while the other cylinder had no diesel supply. The self-designed high pressure water supply system consisted of air booster, gas-liquid booster, high pressure water rail, rail pressure gauge, rail temperature controller and direct water injector. The direct water injector was modified from a Bosch diesel injector. The gasliquid booster with a boost ratio 1:60 was used to pressurize the water in the high pressure water rail. The initial high pressure gas was supplied by an air booster with an output range from 1 to 8 bar. The water injection pressure in the whole test was 35MPa. The schematic of combustion chamber layout is presented in Fig 2.
Fig. 1. Schematic of test bench.
Fig 2. Schematic of combustion chamber layout
A Kistler cylinder pressure sensor was mounted on the top of combustion chamber. An optical encoder was used to track engine position and gave a TTL signal each 0.5°CA. Cylinder pressure, intake temperature and pressure, exhaust temperature, fuel injection timing and duration, water injection timing and duration, emissions were all acquired by corresponding sensors and collected by NI PCI-6250 acquisition card utilizing trigger sampling mode with a sample interval of 0.5 °CA. The controller platform of direct water injection common rail diesel engine test bench was established on the basis of NI CompactRIO system. NI CompactRIO consists of a real-time controller, reconfigurable FPGA chassis and C-series modules. In our test bench, two Drivven DI modules were selected to control diesel direct injection and water direct injection separately. 3. Test Procedure The engine was first started without water injection and no measurement would be carried out until the engine reached a steady state. After reaching a stable condition, the data acquisition began. Around 100 cycles, first 50 cycles without water injection and the last 50 cycles with water injection were recorded each time. Some related engine operation conditions were given in Table 2. Table 2. Engine operation conditions. Type
Value
Diesel injection timing
8°CA BTDC
Diesel injection duration
0.85ms
Engine speed
1000rpm
Water injection timing
180°,150°,120°,90°,60°,30°CA BTDC
Water injection duration
0.3ms,0.4ms, 0.8ms
Water injection pressure
35MPa
Water injection temperature
Ambient temperature(15℃)
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Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
4. Results and Discussion 4.1. Effect of Water Injection on Combustion Characteristics Fig 3 depicts the comparison of P-V diagrams of water injection cycle and no water injection cycle. Diesel is injected 8°CA BTDC with the injection duration of 0.85ms . Water is injected 180°CA BTDC with the injection duration of 0.4ms. The IMEP of no water injection cycle is 0.8931MPa, while the IMEP of water injection cycle is 0.9296. The IMEP of water injection cycle is increased by 4.09% compared with no water injection cycle under the same diesel injection timing and duration, which means indicated thermal efficiency is improved by 4.09%.
Fig. 3. Comparison of cylinder pressure under water cycle and dry cycle
As shown in Fig3, the cylinder pressure of water injection cycle is lower than that of dry cycle in the compression stroke, which means the negative work of compression stroke is reduced. The negative work of compression stoke is reduced by 2.33%. Meanwhile the cylinder pressure of water injection cycle is higher than that of dry cycle in the power stroke, which means positive work of power stroke is enhanced. The increment of power stroke negative work is 1.76%. The work variation in intake and exhaust stroke is negligible. The work reduction of compression stroke and the work increment of power stroke are the main sources of thermal efficiency enhancement. The heat absorption of injected water contributes mainly to the lower cylinder pressure of compression stroke. The cylinder pressure of power stroke of water cycle becomes higher because additional working fluid is added into cylinder. Combustion is retarded slightly after water injection as is shown in Fig 4. CA10 is retarded from 358.5°CA to 359°CA. Analysis suggests that the lower cylinder temperature and pressure in the late compression stroke resulting from heat absorption of the injected water results in the slight combustion start phase delay. CA50 is also retarded slightly from 363.5°CA to 365°CA. The minor differences of CA10, CA50 between water injection and dry cycles illustrates that small amount of water injection in the compression stroke has little retardation effect on combustion.
Fig. 4. Comparison of cylinder pressure and heat release rate under water cycle and dry cycle
Fig. 5. Comparison of heat release rate and cumulative heat release of water cycle and dry cycle
Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
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The thermal efficiency enhancement comes from heat absorption of water evaporation in the compression stroke and the additional working fluid mass increment in the power stroke. All these lead to a conclusion that physical effect dominates under little amount of water injection in compression stroke conditions. The heat release rates and cumulative heat releases of water injection and dry cycle are compared in Fig5. The start phase of cumulative heat release of water injection cycle is later compared with no water injection cycle. Then both cumulative heat releases begin to increase. The cumulative heat release of water injection cycle increases faster. The cumulative heat release of water injection cycle becomes higher than no water injection cycle after around 364°CA until the end phase, which means more heat is absorbed by the working fluid. 4.2. Effect of Water Injection Timing on Thermal Efficiency The indicated efficiency enhancements of different water injection timings under same engine operating condition are compared in Fig 6. The water injection duration is 0.4ms. It is noticed that the thermal efficiency enhancement decreases from 4.09% to 2.10% as the water injection timing retards.
Fig. 6. Indicated thermal efficiency enhancements of different water injection timings
Cylinder pressures of same water injection duration with different injection timings are compared in Fig 7. It is observed that the cylinder pressures of compression stroke are different from each other, while cylinder pressures from 15°CA ATDC to the end of power stroke are quite close to each other. The injected water has a strong cooling effect that changes the compression pressures significantly. It takes time for the injected water to evaporate. However, after 15°ATDC, it is definite that all the in-cylinder water evaporates no matter the how late the injection timing is. The reason is that after the occurrence of combustion the cylinder temperature becomes so high that the evaporation speed is tremendously accelerated. Enough time is provided for water to evaporate.
Fig. 7. Cylinder pressures of different water injection timings
Fig. 8. Comparison of the reduction of negative compression stroke’s work and the increment of positive power stroke’s work
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Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
Fig 8 illustrates the negative work reductions of compression stroke and positive work increments of power stroke of same water injection duration (0.4ms) at different injection timings. It is noticed that the positive work increments of power stroke of different injection timing operating points are close to each other except for the 30°CA injection timing operating point, while the negative work reductions of compression stroke goes down as the injection timing retards. Water starts to absorb heat and evaporate in cylinder after being injected, which gives rise to the drop of cylinder pressure. It is obvious that the later water is injected, the later the cylinder pressure starts to drop, and the smaller quantity of cumulative reductions of negative work of compression stroke is realized. With enough time provided, which means the injection timing is not too late, all injected water will evaporate to become steam before diesel combustion starts. In the power stroke, the working fluid mass and components are also almost the same and the heat released by the fuel combustion process is also similar if the injected water has no significant chemical influence on the combustion process. Similar working fluid components and mass with similar heat release in the power stroke result in similar cylinder pressure. So it can be proved by the close to each other expansion pressure lines that, small amount of water injection in the compression stroke with enough time to evaporate before combustion starts does not have significant chemical effect on the combustion process and the influences on combustion process is dominated by the heat absorption and the addition of working fluid. Test points with 0.3ms water injection duration share the same tendency with different injection timings. However, when injection timing retards to 30°CA BTDC, the evaporation process doesn’t finish before diesel combustion starts. The local evaporation and endothermic effect of water cause uneven temperature distribution and oxygen concentration distribution, which have a significant chemical effect on diesel combustion process. So the positive work of power stroke with 30°CA BTDC injection timing is different from other test points. When the water injection duration increases to 0.8ms, the trend of thermal efficiency enhancement varying with water injection timing is different from that of short injection durations of 0.3ms and 0.4ms. As can be seen in Fig 9, the thermal efficiency enhancements are all below 1% except for -30°CA BTDC point, which means no significant changes of thermal efficiency appear when water injection timing varies from 180°CA BTDC to 60°CA BTDC.
Fig. 9. Indicated thermal efficiency enhancements of different water injection timings
Fig. 10. Comparison of cylinder pressure under water cycle and dry cycle
More detailed information is revealed in the P-φ diagram. The P-φ diagram of -90°CA BTDC injection timing is shown in Fig 10 as an example. It is noted that the cylinder pressures of water injection and no water injection cycles have no obvious differentiations. Other operating points with injection timings varying from 180°CA BTDC to 60°CA BTDC are similar. Analysis suggests that, the spray penetration is much longer when the injection duration increases to 0.8ms. Spray wall impingement phenomenon occur when injection timing is too early in the compression stroke with low ambient pressure. The mixing of injected water and engine oil will lead to emulsification of engine oil, which has negative impact on engine performance. When water injection timing retards to 30°CA BTDC, the thermal efficiency enhancement rises to 2.42%. The increase of in-cylinder pressure at injection timing suppresses the occurrence of spray wall impingement. Fig 11 shows the P-φ diagram of 30°CA BTDC injection timing. 2 °CA after injection timing, the cylinder pressure curves of water injection cycle and no water injection cycle begin to separate. The heat absorption of water evaporation reduces the cylinder pressure, retards the combustion process and extends the expansion line in power stroke.
Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
Fig. 11. Comparison of cylinder pressure under water cycle and dry cycle
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Fig. 12. Comparison of the reduction of negative compression stroke’s work and the increment of positive power stroke’s work
As is shown in Fig 12, the reduction of negative compression stroke’s work is 0.81J, very little compared with 16.86J, the increment of positive power stroke’s work. The thermal efficiency enhancement mainly comes from combustion retardation and working fluid addition. In general, for small water injection durations, early injection timing is more beneficial, while for large water injection durations, late injection timing is more beneficial. 4.3. Effect of Water Injection Duration on Thermal Efficiency Since spray wall impingement occurs in most injection timings with 0.8ms water injection duration, this part will focus on 0.3 and 0.4ms injection durations. The correlation between indicated thermal efficiency and water injection timing with 0.3 and 0.4ms water injection duration are given in Fig 13. Both injection durations share the same trend. As the water injection retards, the indicated thermal efficiency decreases. The indicated thermal efficiency enhancement of 0.3ms duration is always lower than that of 0.4ms with the same water injection timing.
Fig. 13. Comparison of Indicated thermal efficiency enhancement under 0.3ms water injection duration and 0.4ms water injection duration
Fig. 14. Comparison of the reduction of negative compression stroke’s work and the increment of positive power stroke’s work under 0.3ms water injection duration and 0.4ms water injection duration.
The detailed reason is revealed by fig 14. The reduction of compression stroke work of 0.3ms duration is always lower than that of 0.4ms at the same injection timing, while the enhancement of power stroke work of 0.3ms is also lower than that of 0.4ms in most same injection timing conditions. Less water absorbs less heat and also provides less working fluid addition in the power stroke. However, as the water injection duration rises to 0.8ms, the indicated thermal efficiency enhancement is not significant at most injection timings due to the water spray wall impingement and engine oil emulsification. If the water injection further increases, the combustion is deteriorated and the indicated thermal efficiency decreased. Under test conditions, when the water injection duration is more than 1.4ms, the indicated thermal efficiency of water cycle becomes lower than that of dry cycle whatever the injection
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Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
timing is. In short, as the injection duration increases, the indicated thermal efficiency goes up first until reach the peak, and then goes down. Under test conditions, the best water duration is 0.4ms. 5. Conclusion The effect of early direct water injection on the indicated thermal efficiency of diesel engine is investigated in this study. Conclusions drawn are summarized as follows: 1. Compression stroke direct water injection has a slight retardation effect on diesel combustion. 2. Small amount of direct water injection in the compression stroke improves the indicated thermal efficiency. The heat absorption of water evaporation reduces cylinder temperature and pressure and leads to the reduction of negative compression stroke’s work. Water evaporates to become steam and add to the working fluid in cylinder. Positive stroke’s work is increased due to the addition of working fluid. 3. Large amount of direct water injection in the early stage of compression stroke has no effect on indicated thermal efficiency in that the wall impingement occurs with relatively low in-cylinder pressure. 4. Early injection timing is beneficial for small water injection duration, while late injection timing is beneficial for relatively larger water injection duration. 180°CA BTDC is the best water injection timing of operating conditions with 0.3 and 0.4ms water injection duration during compression stroke. 5. With increasing water injection duration, the indicated thermal efficiency goes up first until reaches the peak and then goes down. Further increasing water injection duration deteriorates combustion process and has negative impacts on thermal efficiency. The highest thermal efficiency enhancement is achieved under 0.4ms water injection duration and 180°CA BTDC water injection timing condition with 4.08% thermal efficiency enhancement. References [1] Matheaus, A., Ryan, T., Daly, D., Langer, D. et al., "Effects of PuriNOx™ Water-Diesel Fuel Emulsions on Emissions and Fuel Economy in a Heavy-Duty Diesel Engine," SAE Technical Paper 2002-01-2891, 2002, doi:10.4271/2002-01-2891. [2] Kadota T, Yamasaki H. Recent advances in the combustion of water fuel emulsion. Progress in Energy and Combustion Science 2002;28(5):385e404. [3] “Impacts of Lubrizol’s PuriNOx Water/Diesel Emulsion on Exhaust Emissions from Heavy-Duty Engines”, EPA report 420-P-02-007, 2002. [4] Hountalas, D., Mavropoulos, G., and Zannis, T., "Comparative Evaluation of EGR, Intake Water Injection and Fuel/Water Emulsion as NOx Reduction Techniques for Heavy Duty Diesel Engines," SAE Technical Paper 2007-01-0120, 2007, doi:10.4271/2007-01-0120. [5] Andrews, G.E., Bartle, K. D., Pang, S.W., et al. The reduction of Diesel Particulate Emissions, SAE Technical Paper No.880348, 1988. [6] Brusca, S. and Lanzafame, R., "Evaluation of the Effects of Water Injection in a Single Cylinder CFR Cetane Engine," SAE Technical Paper 2001-01-2012, 2001, doi:10.4271/2001-01-2012. [7] B. Tesfa, R. Mishra, F. Gu, A.D. Ball, Water injection effects on the performance and emission characteristics of a CI engine operating with biodiesel, Renewable Energy, Volume 37, Issue 1, January 2012, Pages 333-344, ISSN 0960-1481. [8] Arto Sarvi, Pia Kilpinen, Ron Zevenhoven, Emissions from large-scale medium-speed diesel engines: 3. Influence of direct water injection and common rail, Fuel Processing Technology, Volume 90, Issue 2, February 2009, Pages 222-231, ISSN 0378-3820 [9] Stanglmaier RH, Dingle PJ, Stewart DW. Cycle-Controlled Water Injection for Steady-State and Transient Emissions Reduction From a Heavy-Duty Diesel Engine. ASME. J. Eng. Gas Turbines Power. 2008;130(3):032801-032801-7. doi:10.1115/1.2830856. [10] Shah, S., Maiboom, A., Tauzia, X., and Hétet, J., "Experimental Study of Inlet Manifold Water Injection on a Common Rail HSDI Automobile Diesel Engine, Compared to EGR with Respect to PM and Nox Emissions and Specific Consumption," SAE Technical Paper 2009-01-1439, 2009, doi:10.4271/2009-01-1439. [11] Samec, N., Dibble, R.W, Chen, J.H., Pagon, A.“Reduction of NOx and Soot Emission by Water Injection During combustion in a diesel engine”, FISITA Automotive Congress paper F2000A075, 2000 [12] Hoppe, F., Thewes, M., Baumgarten, H., & Dohmen, J. (2016). Water injection for gasoline engines: Potentials, challenges, and solutions.International Journal of Engine Research, 17(1), 86-96. [13] Chadwell, C.J., “Effect of diesel and water coinjection with real-time control on diesel engine performance and emissions”, SAE paper 2008-01- 1190, 2008 [14] Chybowski L, Laskowski R, Gawdzińska K. An overview of systems supplying water into the combustion chamber of diesel engines to decrease the amount of nitrogen oxides in exhaust gas[J]. Journal of Marine Science and Technology, 2015, 20(3): 393-405. [15] Gronowicz J (2004) Ochrona środowiska w transporcie lądowym. ITE, Radom
ScienceDirect
Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Available Energy Energy Procedia Procedia 00 00 (2017) (2017) 000–000 000–000
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Energy Procedia 142 Energy Procedia 00(2017) (2017)1251–1258 000–000 www.elsevier.com/locate/procedia
9th International Conference on Applied Energy, ICAE2017, 21-24 August 2017, Cardiff, UK
Effect of direct water injection during compression stroke on 15th International Symposium on District Heating and Cooling thermal The efficiency optimization of common rail diesel engine a a demand-outdoor Assessing theKang feasibility of ausing theChao heat Zhehao Zhanga, Zhe , Lang Jiang , Yuedong , Jun Denga, Zongjie Hua, temperature function for a long-term Liguang Lia, Zhijundistrict Wua,* heat demand forecast a aSchool
School of of Automotive Automotive Studies Studies Tongji Tongji University, University, Shanghai Shanghai and and 201804, 201804, China China
I. Andrića,b,c*, A. Pinaa, P. Ferrãoa, J. Fournierb., B. Lacarrièrec, O. Le Correc a
IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal Abstract b Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France c
Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France
The increasingly strict emissions regulations put forward higher request of NOx emissions control to diesel engines. Water addition is considered to be an effective way to reduce NOx emissions. However, most studies around the world concerned mainly about the effect of water addition on NOx reduction. The effect of water addition on diesel engine efficiency was not paid asAbstract much attention as on emissions. A series of experiments were carried out on test bench based on a two cylinder diesel engine with the modifications of adding common rail system and direct water injection system. The effects of direct water injection on diesel combustion and indicated thermal addressed efficiency inoptimization studied theeffective mechanism of thermal efficiency District heating networks are commonly the literaturewere as one of theand most solutions for decreasing the improvement due to compression stroke water injection was revealed. The influences of water injection duration and water greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat injection timing arechanged also studied. showed compression stroke directheat water injection is beneficial to decrease, thermal sales. Due to the climateResults conditions and that, building renovation policies, demand in the future could efficiency. test conditions up to 4.08% indicated thermal efficiency enhancement is achieved. The thermal efficiency prolongingUnder the investment return period. enhancement is mainly the reduction of negative stroke’s work due to the heat absorption ofdemand water The main scope of this attributed paper is totoassess the feasibility of usingcompression the heat demand – outdoor temperature function for heat evaporation and the increment of positive power stroke’s work due to the addition of working fluid. For small water injection forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 duration, injection timing in the compression leads Three to higher thermal efficiency, injection at and late stage the buildingsearlier that vary in both construction period andstroke typology. weather scenarios (low,while medium, high) three in district compression stroke is were more developed suitable for(shallow, larger water addition quantity. at first until reaches its peak renovation scenarios intermediate, deep). ToThermal estimateefficiency the error, rises obtained heat demand values were value, and with thenresults drops from witha dynamic increasingheat water injection increasing water by injection duration deteriorates compared demand model,duration. previouslyFurther developed and validated the authors. combustion and has negative impact on thermal efficiency. The highest thermal efficiency enhancement is achieved 0.4ms The results showed that when only weather change is considered, the margin of error could be acceptable for someunder applications water injection duration and 180°CA BTDC water timing condition. (the error in annual demand was lower than 20%injection for all weather scenarios considered). However, after introducing renovation ©scenarios, 2017 Thethe Authors. Published by Elsevier Ltd. (depending on the weather and renovation scenarios combination considered). error value increased up to 59.5% © 2017 The Authors. Published by Elsevier Ltd. committee of the 9th International Conference on Applied Energy. Peer-review under responsibility of the scientific The value of slope coefficient of increased on average within the 9th range of 3.8% up to 8% per corresponds to the Peer-review under responsibility the scientific committee of the International Conference ondecade, Appliedthat Energy. decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and Keywords: Direct water Diesel engine, Thermal efficiency Keywords: Direct water injection, injection, DieselOn engine, Compression stroke, Thermal efficiency renovation scenarios considered). the Compression other hand, stroke, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and ** Corresponding Corresponding author. author. Tel.: Tel.: +86-139-1674-7031 +86-139-1674-7031 Cooling. E-mail E-mail address: address: [email protected] [email protected]
Keywords: Heat demand; Forecast; Climate change 1876-6102 © 1876-6102 © 2017 2017 The The Authors. Authors. Published Published by by Elsevier Elsevier Ltd. Ltd. Peer-review Peer-review under under responsibility responsibility of of the the scientific scientific committee committee of of the the 9th 9th International International Conference Conference on on Applied Applied Energy. Energy.
1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling.
1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 9th International Conference on Applied Energy. 10.1016/j.egypro.2017.12.514
Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
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1. Introduction Supplying water into the cylinder is considered to be one of the most promising internal measures of diesel engines to reduce NOx emissions. Generally, fuel water emulsion, intake water injection and direct water injection are the three main approaches utilized to provide water into combustion chamber. In water fuel emulsion fuel and specific ratio of water are mixed by a trace content of surfactant. By using water fuel emulsion, NOx, PM and soot emissions are reduced simultaneously[1]. The micro- explosion phenomena in the emulsion spray induced by volatility differences between fuel and water improve the air entrainment, which lead to better atomization[2,3]. D.T.Hountalas et al. utilized a multi-zone combustion model to compare and evaluate EGR, intake water injection and fuel water emulsion in NOx reduction and found out that, at the same NOx reduction level, only soot emissions of fuel water emulsion decreased[4]. The drawback of water fuel emulsion is the restrict of fixed water to fuel ratio since there are different best water to fuel ratios for different engine operating conditions[3,5]. Intake water injection is the easiest method to introduce water to cylinder, which needs the minimal modification to the existing engine structure. S. Brusca and R. Lanzafame investigated the effect of water injection on a CFR Cetane Engine with water to fuel mass ratio varying from 0 to 1.5 and reported that NOx concentration in exhaust gas decreases as water to fuel mass ratio increases. Maximum NOx reduction up to 40% was achieved when W/F ratio was 1.5[6]. The effect of intake manifold water injection of a CI engine fueled with biodiesel was studied by B.Tesfa et al. Results showed that water injection does not show clear effect on BSFC and thermal efficiency at intermediate and higher engine loads, but has a negative impact of maximum 4% reduction of BSFC at low engine loads. They also found out that water injection leaded to NOx reduction by up to 50% over entire operating range[7]. One of the biggest advantages of direct water injection is the variable suitable water to fuel ratio depending on different engine operating conditions. Arto Sarvi et al. investigated the effect of direct water injection (DWI) on the emissions on large-scale medium-speed turbo-charged diesel engines and found out that DWI results in significant NOx and slight HC emissions reduction and slight soot and PM emissions increment[8]. Rudolf H. Stanglmaier et al. developed a diesel water coinjection system and mounted it on a production Volvo D-12 heavy duty engine. A conclusion is drawn that fuel water coinjection is effective for steady state NOx, HC, CO and smoke emissions[9]. The effect of water injection on combustion can be wildly divided into three parts: thermal effects, chemical effects and dilution effects [10]. In regard to thermal effects, evaporation cooling of water in air charge increases the density and air mass of intake charge. Water vapor in the cylinder also causes higher specific heat capacity of the intake charge. Both give rise to lower combustion temperatures and lower NOx emissions[6,10,11]. In cylinder water dilution effect refers to the reduction of concentration of oxygen per unit volume or mass of charge caused by inert medium introduction[12,13]. The chemical effect is that supplied water decreases the concentration of atomic oxygen and suppresses NO formation reactions[14,15]. Most researches focused on emissions and a widely accepted conclusion is that the introduction of water has great benefits on NOx reduction with little or slight effect on thermal efficiency. This study concentrated on engine thermal efficiency and revealed the mechanism of efficiency enhancement contributed by water injection. 2. Experimental Setup The test is conducted on a common rail diesel engine retrofitted from a two cylinder mechanical pump diesel engine. Engine specifications are shown in Table 1. Table 1. Engine Specifications. Type
Value
Type
Value
Displaced volume
808ml
Number of Valves
2
Stroke
114mm
Exhaust Valve Open
225°BTDC
Bore
95mm
Exhaust Valve Close
15°ATDC
Connecting Rod
255mm
Inlet Valve Open
15°BTDC
Compression Ratio
17:1
Inlet Valve Close
225°ATDC
Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
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The schematic diagram of diesel engine direct water injection test bench is shown in Fig 1. A fuel supply system provided from 200bar to 1600bar high pressure diesel. A Bosch diesel injector was utilized to inject diesel directly into one test cylinder while the other cylinder had no diesel supply. The self-designed high pressure water supply system consisted of air booster, gas-liquid booster, high pressure water rail, rail pressure gauge, rail temperature controller and direct water injector. The direct water injector was modified from a Bosch diesel injector. The gasliquid booster with a boost ratio 1:60 was used to pressurize the water in the high pressure water rail. The initial high pressure gas was supplied by an air booster with an output range from 1 to 8 bar. The water injection pressure in the whole test was 35MPa. The schematic of combustion chamber layout is presented in Fig 2.
Fig. 1. Schematic of test bench.
Fig 2. Schematic of combustion chamber layout
A Kistler cylinder pressure sensor was mounted on the top of combustion chamber. An optical encoder was used to track engine position and gave a TTL signal each 0.5°CA. Cylinder pressure, intake temperature and pressure, exhaust temperature, fuel injection timing and duration, water injection timing and duration, emissions were all acquired by corresponding sensors and collected by NI PCI-6250 acquisition card utilizing trigger sampling mode with a sample interval of 0.5 °CA. The controller platform of direct water injection common rail diesel engine test bench was established on the basis of NI CompactRIO system. NI CompactRIO consists of a real-time controller, reconfigurable FPGA chassis and C-series modules. In our test bench, two Drivven DI modules were selected to control diesel direct injection and water direct injection separately. 3. Test Procedure The engine was first started without water injection and no measurement would be carried out until the engine reached a steady state. After reaching a stable condition, the data acquisition began. Around 100 cycles, first 50 cycles without water injection and the last 50 cycles with water injection were recorded each time. Some related engine operation conditions were given in Table 2. Table 2. Engine operation conditions. Type
Value
Diesel injection timing
8°CA BTDC
Diesel injection duration
0.85ms
Engine speed
1000rpm
Water injection timing
180°,150°,120°,90°,60°,30°CA BTDC
Water injection duration
0.3ms,0.4ms, 0.8ms
Water injection pressure
35MPa
Water injection temperature
Ambient temperature(15℃)
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Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
4. Results and Discussion 4.1. Effect of Water Injection on Combustion Characteristics Fig 3 depicts the comparison of P-V diagrams of water injection cycle and no water injection cycle. Diesel is injected 8°CA BTDC with the injection duration of 0.85ms . Water is injected 180°CA BTDC with the injection duration of 0.4ms. The IMEP of no water injection cycle is 0.8931MPa, while the IMEP of water injection cycle is 0.9296. The IMEP of water injection cycle is increased by 4.09% compared with no water injection cycle under the same diesel injection timing and duration, which means indicated thermal efficiency is improved by 4.09%.
Fig. 3. Comparison of cylinder pressure under water cycle and dry cycle
As shown in Fig3, the cylinder pressure of water injection cycle is lower than that of dry cycle in the compression stroke, which means the negative work of compression stroke is reduced. The negative work of compression stoke is reduced by 2.33%. Meanwhile the cylinder pressure of water injection cycle is higher than that of dry cycle in the power stroke, which means positive work of power stroke is enhanced. The increment of power stroke negative work is 1.76%. The work variation in intake and exhaust stroke is negligible. The work reduction of compression stroke and the work increment of power stroke are the main sources of thermal efficiency enhancement. The heat absorption of injected water contributes mainly to the lower cylinder pressure of compression stroke. The cylinder pressure of power stroke of water cycle becomes higher because additional working fluid is added into cylinder. Combustion is retarded slightly after water injection as is shown in Fig 4. CA10 is retarded from 358.5°CA to 359°CA. Analysis suggests that the lower cylinder temperature and pressure in the late compression stroke resulting from heat absorption of the injected water results in the slight combustion start phase delay. CA50 is also retarded slightly from 363.5°CA to 365°CA. The minor differences of CA10, CA50 between water injection and dry cycles illustrates that small amount of water injection in the compression stroke has little retardation effect on combustion.
Fig. 4. Comparison of cylinder pressure and heat release rate under water cycle and dry cycle
Fig. 5. Comparison of heat release rate and cumulative heat release of water cycle and dry cycle
Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
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The thermal efficiency enhancement comes from heat absorption of water evaporation in the compression stroke and the additional working fluid mass increment in the power stroke. All these lead to a conclusion that physical effect dominates under little amount of water injection in compression stroke conditions. The heat release rates and cumulative heat releases of water injection and dry cycle are compared in Fig5. The start phase of cumulative heat release of water injection cycle is later compared with no water injection cycle. Then both cumulative heat releases begin to increase. The cumulative heat release of water injection cycle increases faster. The cumulative heat release of water injection cycle becomes higher than no water injection cycle after around 364°CA until the end phase, which means more heat is absorbed by the working fluid. 4.2. Effect of Water Injection Timing on Thermal Efficiency The indicated efficiency enhancements of different water injection timings under same engine operating condition are compared in Fig 6. The water injection duration is 0.4ms. It is noticed that the thermal efficiency enhancement decreases from 4.09% to 2.10% as the water injection timing retards.
Fig. 6. Indicated thermal efficiency enhancements of different water injection timings
Cylinder pressures of same water injection duration with different injection timings are compared in Fig 7. It is observed that the cylinder pressures of compression stroke are different from each other, while cylinder pressures from 15°CA ATDC to the end of power stroke are quite close to each other. The injected water has a strong cooling effect that changes the compression pressures significantly. It takes time for the injected water to evaporate. However, after 15°ATDC, it is definite that all the in-cylinder water evaporates no matter the how late the injection timing is. The reason is that after the occurrence of combustion the cylinder temperature becomes so high that the evaporation speed is tremendously accelerated. Enough time is provided for water to evaporate.
Fig. 7. Cylinder pressures of different water injection timings
Fig. 8. Comparison of the reduction of negative compression stroke’s work and the increment of positive power stroke’s work
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Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
Fig 8 illustrates the negative work reductions of compression stroke and positive work increments of power stroke of same water injection duration (0.4ms) at different injection timings. It is noticed that the positive work increments of power stroke of different injection timing operating points are close to each other except for the 30°CA injection timing operating point, while the negative work reductions of compression stroke goes down as the injection timing retards. Water starts to absorb heat and evaporate in cylinder after being injected, which gives rise to the drop of cylinder pressure. It is obvious that the later water is injected, the later the cylinder pressure starts to drop, and the smaller quantity of cumulative reductions of negative work of compression stroke is realized. With enough time provided, which means the injection timing is not too late, all injected water will evaporate to become steam before diesel combustion starts. In the power stroke, the working fluid mass and components are also almost the same and the heat released by the fuel combustion process is also similar if the injected water has no significant chemical influence on the combustion process. Similar working fluid components and mass with similar heat release in the power stroke result in similar cylinder pressure. So it can be proved by the close to each other expansion pressure lines that, small amount of water injection in the compression stroke with enough time to evaporate before combustion starts does not have significant chemical effect on the combustion process and the influences on combustion process is dominated by the heat absorption and the addition of working fluid. Test points with 0.3ms water injection duration share the same tendency with different injection timings. However, when injection timing retards to 30°CA BTDC, the evaporation process doesn’t finish before diesel combustion starts. The local evaporation and endothermic effect of water cause uneven temperature distribution and oxygen concentration distribution, which have a significant chemical effect on diesel combustion process. So the positive work of power stroke with 30°CA BTDC injection timing is different from other test points. When the water injection duration increases to 0.8ms, the trend of thermal efficiency enhancement varying with water injection timing is different from that of short injection durations of 0.3ms and 0.4ms. As can be seen in Fig 9, the thermal efficiency enhancements are all below 1% except for -30°CA BTDC point, which means no significant changes of thermal efficiency appear when water injection timing varies from 180°CA BTDC to 60°CA BTDC.
Fig. 9. Indicated thermal efficiency enhancements of different water injection timings
Fig. 10. Comparison of cylinder pressure under water cycle and dry cycle
More detailed information is revealed in the P-φ diagram. The P-φ diagram of -90°CA BTDC injection timing is shown in Fig 10 as an example. It is noted that the cylinder pressures of water injection and no water injection cycles have no obvious differentiations. Other operating points with injection timings varying from 180°CA BTDC to 60°CA BTDC are similar. Analysis suggests that, the spray penetration is much longer when the injection duration increases to 0.8ms. Spray wall impingement phenomenon occur when injection timing is too early in the compression stroke with low ambient pressure. The mixing of injected water and engine oil will lead to emulsification of engine oil, which has negative impact on engine performance. When water injection timing retards to 30°CA BTDC, the thermal efficiency enhancement rises to 2.42%. The increase of in-cylinder pressure at injection timing suppresses the occurrence of spray wall impingement. Fig 11 shows the P-φ diagram of 30°CA BTDC injection timing. 2 °CA after injection timing, the cylinder pressure curves of water injection cycle and no water injection cycle begin to separate. The heat absorption of water evaporation reduces the cylinder pressure, retards the combustion process and extends the expansion line in power stroke.
Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
Fig. 11. Comparison of cylinder pressure under water cycle and dry cycle
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Fig. 12. Comparison of the reduction of negative compression stroke’s work and the increment of positive power stroke’s work
As is shown in Fig 12, the reduction of negative compression stroke’s work is 0.81J, very little compared with 16.86J, the increment of positive power stroke’s work. The thermal efficiency enhancement mainly comes from combustion retardation and working fluid addition. In general, for small water injection durations, early injection timing is more beneficial, while for large water injection durations, late injection timing is more beneficial. 4.3. Effect of Water Injection Duration on Thermal Efficiency Since spray wall impingement occurs in most injection timings with 0.8ms water injection duration, this part will focus on 0.3 and 0.4ms injection durations. The correlation between indicated thermal efficiency and water injection timing with 0.3 and 0.4ms water injection duration are given in Fig 13. Both injection durations share the same trend. As the water injection retards, the indicated thermal efficiency decreases. The indicated thermal efficiency enhancement of 0.3ms duration is always lower than that of 0.4ms with the same water injection timing.
Fig. 13. Comparison of Indicated thermal efficiency enhancement under 0.3ms water injection duration and 0.4ms water injection duration
Fig. 14. Comparison of the reduction of negative compression stroke’s work and the increment of positive power stroke’s work under 0.3ms water injection duration and 0.4ms water injection duration.
The detailed reason is revealed by fig 14. The reduction of compression stroke work of 0.3ms duration is always lower than that of 0.4ms at the same injection timing, while the enhancement of power stroke work of 0.3ms is also lower than that of 0.4ms in most same injection timing conditions. Less water absorbs less heat and also provides less working fluid addition in the power stroke. However, as the water injection duration rises to 0.8ms, the indicated thermal efficiency enhancement is not significant at most injection timings due to the water spray wall impingement and engine oil emulsification. If the water injection further increases, the combustion is deteriorated and the indicated thermal efficiency decreased. Under test conditions, when the water injection duration is more than 1.4ms, the indicated thermal efficiency of water cycle becomes lower than that of dry cycle whatever the injection
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Zhehao Zhang et al. / Energy Procedia 142 (2017) 1251–1258 Author name / Energy Procedia 00 (2017) 000–000
timing is. In short, as the injection duration increases, the indicated thermal efficiency goes up first until reach the peak, and then goes down. Under test conditions, the best water duration is 0.4ms. 5. Conclusion The effect of early direct water injection on the indicated thermal efficiency of diesel engine is investigated in this study. Conclusions drawn are summarized as follows: 1. Compression stroke direct water injection has a slight retardation effect on diesel combustion. 2. Small amount of direct water injection in the compression stroke improves the indicated thermal efficiency. The heat absorption of water evaporation reduces cylinder temperature and pressure and leads to the reduction of negative compression stroke’s work. Water evaporates to become steam and add to the working fluid in cylinder. Positive stroke’s work is increased due to the addition of working fluid. 3. Large amount of direct water injection in the early stage of compression stroke has no effect on indicated thermal efficiency in that the wall impingement occurs with relatively low in-cylinder pressure. 4. Early injection timing is beneficial for small water injection duration, while late injection timing is beneficial for relatively larger water injection duration. 180°CA BTDC is the best water injection timing of operating conditions with 0.3 and 0.4ms water injection duration during compression stroke. 5. With increasing water injection duration, the indicated thermal efficiency goes up first until reaches the peak and then goes down. Further increasing water injection duration deteriorates combustion process and has negative impacts on thermal efficiency. The highest thermal efficiency enhancement is achieved under 0.4ms water injection duration and 180°CA BTDC water injection timing condition with 4.08% thermal efficiency enhancement. References [1] Matheaus, A., Ryan, T., Daly, D., Langer, D. et al., "Effects of PuriNOx™ Water-Diesel Fuel Emulsions on Emissions and Fuel Economy in a Heavy-Duty Diesel Engine," SAE Technical Paper 2002-01-2891, 2002, doi:10.4271/2002-01-2891. [2] Kadota T, Yamasaki H. Recent advances in the combustion of water fuel emulsion. Progress in Energy and Combustion Science 2002;28(5):385e404. [3] “Impacts of Lubrizol’s PuriNOx Water/Diesel Emulsion on Exhaust Emissions from Heavy-Duty Engines”, EPA report 420-P-02-007, 2002. [4] Hountalas, D., Mavropoulos, G., and Zannis, T., "Comparative Evaluation of EGR, Intake Water Injection and Fuel/Water Emulsion as NOx Reduction Techniques for Heavy Duty Diesel Engines," SAE Technical Paper 2007-01-0120, 2007, doi:10.4271/2007-01-0120. [5] Andrews, G.E., Bartle, K. D., Pang, S.W., et al. The reduction of Diesel Particulate Emissions, SAE Technical Paper No.880348, 1988. [6] Brusca, S. and Lanzafame, R., "Evaluation of the Effects of Water Injection in a Single Cylinder CFR Cetane Engine," SAE Technical Paper 2001-01-2012, 2001, doi:10.4271/2001-01-2012. [7] B. Tesfa, R. Mishra, F. Gu, A.D. Ball, Water injection effects on the performance and emission characteristics of a CI engine operating with biodiesel, Renewable Energy, Volume 37, Issue 1, January 2012, Pages 333-344, ISSN 0960-1481. [8] Arto Sarvi, Pia Kilpinen, Ron Zevenhoven, Emissions from large-scale medium-speed diesel engines: 3. Influence of direct water injection and common rail, Fuel Processing Technology, Volume 90, Issue 2, February 2009, Pages 222-231, ISSN 0378-3820 [9] Stanglmaier RH, Dingle PJ, Stewart DW. Cycle-Controlled Water Injection for Steady-State and Transient Emissions Reduction From a Heavy-Duty Diesel Engine. ASME. J. Eng. Gas Turbines Power. 2008;130(3):032801-032801-7. doi:10.1115/1.2830856. [10] Shah, S., Maiboom, A., Tauzia, X., and Hétet, J., "Experimental Study of Inlet Manifold Water Injection on a Common Rail HSDI Automobile Diesel Engine, Compared to EGR with Respect to PM and Nox Emissions and Specific Consumption," SAE Technical Paper 2009-01-1439, 2009, doi:10.4271/2009-01-1439. [11] Samec, N., Dibble, R.W, Chen, J.H., Pagon, A.“Reduction of NOx and Soot Emission by Water Injection During combustion in a diesel engine”, FISITA Automotive Congress paper F2000A075, 2000 [12] Hoppe, F., Thewes, M., Baumgarten, H., & Dohmen, J. (2016). Water injection for gasoline engines: Potentials, challenges, and solutions.International Journal of Engine Research, 17(1), 86-96. [13] Chadwell, C.J., “Effect of diesel and water coinjection with real-time control on diesel engine performance and emissions”, SAE paper 2008-01- 1190, 2008 [14] Chybowski L, Laskowski R, Gawdzińska K. An overview of systems supplying water into the combustion chamber of diesel engines to decrease the amount of nitrogen oxides in exhaust gas[J]. Journal of Marine Science and Technology, 2015, 20(3): 393-405. [15] Gronowicz J (2004) Ochrona środowiska w transporcie lądowym. ITE, Radom