Although over the years significant advances have been made in reducing diesel engine emissions, the new stringent emission standards and legislation and the challenge to protect society, animals and nature against air pollution motivate the scientists to perform further studies and research to comply with the new regulations and reduce diesel engine emissions.

The basic engineering methods used by engine manufacturers to control emissions involve combustor design modifications ^[13], optimizing the in-cylinder operating parameters and exhaust after-treatment techniques. However, redesigning a combustor would be a viable option only for future engine design since retrofit costs would apply in this case. Also optimizing the in-cylinder operating parameters by doing some combustor modifications or changing operating conditions would very often result in reduced particle emissions and increased NO_X^[14].There have been trials to produce a very stable emulsion that stays in suspension over a long period of time. If the fuel remains still for many days, larger droplets of the chemically coated water may settle to the bottom of a tank. There have been water-diesel emulsions from Lubrizol and other companies ^[26] for the NOx and PM reduction purpose. They have produced diesel-water emulsion with the aid of emulsifying agents and additives to keep the emulsion stable they produced 20% water-diesel emulsion and achieved 30% reduction in NOx and 50% reduction in PM.

EMULSION FUEL HISTORY:

Engineers have known for years that adding water to fuel brings benefits; water was used in World War II for fueling aircraft. Emulsion fuels has a history going back 82 years beginning in 1931 when Joseph Vance suggested application related to process for making liquid fuel use in heating apparatus or combustion engines. Many researches focused in using water with fuel as an emulsified fuel. Rumours exist that Germany experimented with water in fuel emulsions and synthetic fuels after much of their fuel supply was destroyed during WWII. For the sake of demonstrability we will stick to more easily available documented sources of Emulsified Fuels History ^{[49, 50-52, 27]}

EMULSION FUEL FORMATION

1) water-in-diesel emulsions.

The applications of emulsification technique are generally applied in pharmaceutical, cosmetic, and food production. The potential of using emulsion as an alternative fuel for combustion equipments is worthy of further evaluation. Since the content and quantity of the emulsifier, hydrophilic–Lipophilic balance (HLB), or additives can affect the formation rate and emulsification stability (ES) of the emulsions, systematic investigation on the suitable proportions of diesel oil, emulsifier and additive combination needed to improve emulsification characteristics and fuel properties is required ^[7]. Water fuel emulsion consists of base fuel and water doped with or without a trace content of surfactant. The emulsion is essentially a multi-component fuel that its base fuel and water are not miscible at the molecular level. The immiscibility plays an important role in the phase transformation and shows the phenomena which are qualitatively different from that in the combustion of pure fuel or miscible multi-component fuel. The emulsions of the water in diesel have been investigated by Rudolf W. Gunnerman. The presence of the dispersed water droplet phase within a continuous diesel fuel phase leads to the formation of water-in-diesel emulsion (W/D emulsion). Combustion of a diesel/water emulsion may allow reduction of both NOx and particulates due to two different mechanisms. Reduction of particulates comes from reduction of their non-soluble carbon content and reduction in the sulphur dioxide. ^[3,4,]

2) Diesel-in-water-in-diesel emulsions.

Double emulsions of the type oil/water/oil (O/W/O), where oil is diesel, have been investigated by Lin and Wang. It was found that the viscosity of the double emulsions was higher than for the normal emulsions but the higher viscosity was not a problem in the use of the formulation as a fuel ^[27]. The benefits in terms of reduced emissions obtained with water in-diesel emulsions were obtained also with the O/W/O formulations. The double emulsions seemed to give even lower levels of NOx and CO than the regular emulsions although the differences were relatively small. With regard to engine performance and combustion characteristics the double emulsions gave a higher exhaust gas temperature. The O/W/O emulsions prepared by the ultra-sonic vibrator were shown to have a larger number of smaller dispersed-phase droplets that were more evenly distributed in the outer oil phase, larger emulsion viscosity, and lower separating rates of the water droplets from the emulsions than those emulsions prepared by the mechanical homogenizer. The O/W/O emulsions prepared by the ultra-sonic vibrator were found to cause a more intensive micro-explosion phenomenon, resulting in higher burning efficiency, lower fuel consumption rate and lower, brake specific fuel consumption than those prepared by the mechanical homogenizer. The O/W/O emulsions were found to have a higher fuel consumption rate, brake specific fuel consumption, CO emission, and black smoke opacity than the W/O emulsions. ^[27-30]

3.) Water-in-diesel microemulsions.

Microemulsions are alternatives to emulsions as a method to include water in a very fuel. The terms “microemulsion” and “emulsion” appear to imply that such systems are terribly similar, differing simply within the size of the distributed element; however that's not the case. There are many basic variations between a microemulsion associated an emulsion ^[32]. Microemulsion-based fuel formulations go back to 1976 once Gillberg and Friberg revealed a paper on the employment of water in-diesel microemulsions as fuel ^[33]. Since microemulsions accommodates a lot of smaller domain sizes than emulsions, one could anticipate that superior to emulsions with relevancy the atomization method however there are indications that the other holds true. As mentioned on top of, Qingguo and Gollahalli have reported that macroemulsions, i.e., traditional emulsions, created smaller drops within the flame than microemulsions^[^38]. Within the experiments they used 100% water in supposed Jet-A fuel in each variety of formulations. The overall characteristics of emulsions with relevancy emission levels appear to carry true additionally for microemulsions, i.e., NO_x and CO emissions are reduced compared to neat diesel as fuel ^[34], makes an attempt have additionally been created to feature vegetable oils into water-in-diesel microemulsions, therefore combining two approaches: replacement of hydrocarbons by glyceride oils and introducing water into the fuel^[^35]. Systematic studies are created on combustion of microemulsions supported hydrocarbons of variable chain lengths ^[36-37]. Special attention was paid to the vaporization behavior beneath dynamic heating conditions. The results indicated that the microstructure of the microemulsion contend a job within the physical effects associated with the micro explosion, and, thus, to the combustion method. Not a lot of has been revealed on water-in-diesel microemulsions in recent years. it's most likely faithful say that the benefits of the microemulsion approach, specifically the thermo dynamical stability, don't complete the disadvantage of the a lot of higher loading of surfactants required microemulsion formulation compared to an emulsion formulation. The microemulsion route is maybe too pricey

4) Water-in-diesel Nanoemulsion.

Nanoemulsions are a class of emulsions that can be transparent or translucent (droplet size range of 50 to 200 nm) or ‘milky’ (up to 500 nm). ^[39] Unlike microemulsions, which are transparent and thermodynamically stable, nanoemulsions are only kinetically stable. ^[43], However, W/O nanoemulsions are receiving increased attention since they were first reported by Landfester et al^{. [45]} Depending on the preparation method, different droplet size distributions are achieved, explaining why the route of preparation can remarkably influence the emulsion stability. Due to their small droplet size, nanoemulsions may appear transparent, and Brownian motion prevents sedimentation or creaming, hence receive increased stability. The formation of emulsions with droplet size in the nanometer range (typically in the range of 50 to 200 nm) can be achieved either by high-energy emulsification methods (e.g., by high-shear stirring, high-pressure homogenizers or ultrasound generators) ^[47]. In the experiments they used 14% water in so-called diesel fuel formulations. The general characteristics of emulsions with regard to emission levels seem to hold true also for nanoemulsion, i.e., NOx and CO emissions are reduced compared to neat diesel as fuel. The stability of the studied emulsions increases with increasing the total emulsifier concentration at low water content. Regarding the emission characteristics, it was found that a lower concentration of nitric oxide (NO) was emitted, when the emulsions were used as the engine fuel. Also, the concentration of the CO2 emission is higher in emulsion fuel when compared to pure diesel fuel. The emulsions had lower exhaust gas temperatures and lower Calorific values as expect ^[26].

5.) Water-in-biodiesel emulsions

Biodiesel has attractive fuel properties such as excellent biodegradability and lubricity, almost no emissions of sulfur oxides, PAH and n-PAH, reduced CO2, PM and CO emission, superior combustion efficiency, etc. However, burning of biodiesel generally produces higher levels of NOx emissions, primarily due to its high oxygen content. The emulsification technology has been considered to reduce the NOx emission level of fossil fuel. The majority of water-in-fuel emulsions relate to diesel and other hydrocarbon fuels, but there are also a few papers that deal with the combustion characteristics and the emissions from emulsions of water-in-triglycerides, i.e., water-in-biodiesel. In a study where soybean, sunflower, palm oil emulsions were compared with diesel emulsions it was shown that engine performance, fuel consumption and wear resistance were all comparable for the two types of fuels ^[57].It was found that water-in-biodiesel fuel, containing15%water, gave lower NOx and smoke emissions than plain biodiesel, which is in line with comparisons of emissions from water-in-diesel emulsions and neat diesel, ^[58]. In addition, the W/O biodiesel emulsion was found to have a smaller mean droplet size, lower volumetric fraction of the dispersed and the highest heating value among the test fuels, if the water content is deducted from the calculation of the heating value It was found that NOx emissions were generally lower for vegetable oils than for regular diesel and the values were reduced for both fuels when water was included in the form of an emulsion. CO emissions were higher for the vegetable oil emulsions than for the diesel emulsions although both values were low. ^[55]

6.) Biodiesel -in-Water-in- Biodiesel (O/W/O) emulsions.

Biodiesel, which is produced from vegetable oils, animal fats or used cooking oils, can be used as an alternative fuel for diesel engines. The high oxygen content of biodiesel not only enhances its burning efficiency, but also generally promotes the formation of more nitrogen oxides (NOx) during the burning process. Biodiesel, produced by means of Transesterification reaction accompanied with a per-oxidation process, was emulsified to form three-phase O/W/O emulsions. The effects of the emulsification variables such as hydrophilic Lipophilic balance (HLB), and water content on the fuel properties and emulsion characteristics of O/W/O emulsions were investigated. The kinematic viscosity, specific gravity and carbon residual of the biodiesel emulsions were larger than those of the neat biodiesel. If the water content is deducted from the calculation of the heating value the biodiesel product was then emulsified with distilled water and emulsifying surfactant by a high-speed mechanical homogenizer to produce a three-phase oil-droplets-in-water-droplets-in-oil (i.e. O/W/O) biodiesel emulsion. A four-stroke diesel engine, in combination with an eddy-current dynamometer, was used to investigate the engine performance and emission characteristics of the biodiesel, the O/W/O biodiesel emulsion, The experimental results show that the O/W/O emulsion has the lowest carbon dioxide (CO2) emissions, exhaust gas temperature, and heating value, and the largest brake specific fuel consumption, fuel consumption rate, and kinematic viscosity of the four tested fuels. The increase of engine speed causes the increase of equivalence ratio, exhaust gas temperature, CO2 emissions, fuel consumption rate, and brake specific fuel consumption, but a decrease of NOx emissions.^[^53-54]

7.) Water-biodiesel-diesel nanoemulsions

The presence of water in fuel emulsions can reduce the NOx emissions. The interaction of biodiesel and surfactant concentrations of water-biodiesel-diesel emulsions on diesel engine exhaust emissions are unclear and need investigation.. Attempts have also been made to add biodiesel into water-in-diesel nanoemulsion, thus combining two approaches: replacement of hydrocarbons by triglyceride oils and introducing water into the fuel. The biggest difference between our nano-emulsion fuel and other emulsion fuel is in the size of the water particles. Compared to a water particle diameter of about 10 μm in conventional emulsion fuel, the size of the water particles in our nano-emulsion fuel is only about 300 nm. As a result, even with the same amount of water added, our nano-emulsion fuel contains 37,000 times more water particles with 33 times more contact surface area compared to conventional emulsion fuel. Consequently, the water-oil boundaries increase drastically and the effects of emulsion fuel are increased substantially. When the size of the water particles becomes smaller, the stability of the emulsion improves drastically. The separation of water and oil is largely due to the differences in relative weight (density) between the two. As a result, water which has a larger density, will precipitate, agglomerate and become one. In this case, the speed of the precipitation is directly proportional to the square of the diameter of the water particle according to Stokes Law. [40-42] the results showed that biodiesel nanoemulsions reduced the NOx emissions compared to biodiesel blends at the same biodiesel concentrations. Increasing the surfactant concentration at constant water (10%) and biodiesel concentrations produced higher engine powers. However, biodiesel nanoemulsions significantly increased the BSFC compared to the biodiesel-diesel blends and diesel fuels. Biodiesel nanoemulsions reduced the NOx emissions and exhaust temperature but increased the BSFC and CO emissions. ^[56]

WATER-IN-DIESEL AND CHARCOAL EMULSION FUEL:

Coal contains carbon particles and its higher calorific value is good comparatively. Use of coal can be easy by gasification and liquefaction process. But using coal-in- diesel oil with the help of emulsion process can be a new concept in the path of an alternative fuel. Coal is non-renewable sources so it restricts the use of coal-in- diesel oil as an alternate fuel. By microemulsion of coal particles in diesel oil with proper surfactant, coal-oil can be prepared. Charcoal can be emulsified in diesel and better stability can be obtained by selecting proper surfactants .Wood charcoal has bit less calorific value as compare to the gasoline and diesel but low ash content wood can burned effectively. Emulsification process is the most important in study of charcoal slurry, Stability of charcoal-diesel slurry must be as more as possible. In support of this, Jamil Ghojel, et al from Melbourne, Australia had checked Performance, emissions and heat release characteristics of direct injection diesel engine operating on diesel oil emulsion in 2006. In this paper they presented measurements of the performance and NOx and hydrocarbon emissions of a diesel engine operating on a typical diesel oil emulsion and examine through the use of heat release analysis differences found during its combustion relative to standard diesel in the same engine. Viscosity can be obtained nearer to 30 cP which is almost nearer to diesel oil. Water is added in slurry to provide some time during injection and reduce combustion temperature which ultimately reduces the production of NOx Fuel. The data reveal that the sulfur and wax contents decreased as water or water plus charcoal content increased, with no noticeable effect on the density, calorific value and pour point relative to those of the pure fuel oil. The viscosity of the fuel oil-water emulsion fuels decreased as the water content increased. On the other hand, the viscosity of the fuel oil-water-charcoal emulsion fuels increased as the charcoal content increased. ^{[46, 47, 48]}

WATER-IN-DIESEL AND ALUMINA NANO-PARTICLES EMULSION FUEL:

Water/diesel emulsion fuel is prepared by the emulsification method by adding the alumina nano-particles. The alumina nano-particles are blended with the water–diesel emulsion fuel in the mass fractions systematically. The nano particles are made by applying a plasma arc to aluminum nano-powder submerged in water. The average diameter of the aluminum nano-particles is about 40–60 nm and they are covered with thin layers of aluminum oxide due to the high oxidation activity of pure aluminum. This provides a large contact surface area with water and high activity for the decomposition of hydrogen from water during the combustion process. During combustion the alumina serves as a catalyst and the coated aluminum nano-particles are denuded and decompose the water to yield the hydrogen. The combustion of the diesel fuel mixed with aqueous aluminum nano-fluid shows the following phenomena: total combustion heat increases while the concentration of smoke and nitrous oxide in the exhaust emission from diesel engine are decreased Aluminum nano-powder has a very high activity and can react with water at temperatures from 400 to 660 °C to generate hydrogen and improve fuel combustion. The cited studies have shown that aluminum nano-powder promotes fuel combustion. Therefore, in this study, homemade nano-fluid in the form of aluminum nano-particles coated by alumina submerged in water is added to diesel fuel to explore the effects on fuel consumption, exhaust emission, and combustion features of a diesel engine. Aluminum nano-powder can react with water at high temperature and generate hydrogen, promoting the combustion of the fuel. Because the aluminum is nanometer size, it has more surface area and higher activity to decompose the hydrogen from water and increase combustion heat. Making aqueous aluminum nano-fluid for combustion involves the use of an ultrasonic vibrator to produce emulsified nano-aluminum liquid in a molecule structure of H₂O.Al₂O₃ an agitator is applied to constantly agitate the nano-aluminum solution and diesel fuel before the mixed fuel is injected into the combustion cylinder. The experiments are conducted at a constant speed of 1500 rpm and the results revealed a substantial enhancement in the performance and reduction in the harmful pollutants due to the incorporation of alumina nano-particles in the water–diesel emulsion fuel. Biodiesel emulsions are considered as the propitious alternative fuels for diesel engines. Henceforth, the present study provides a tangible pathway to prepare and to ameliorate the biodiesel emulsion fuel on incorporating potential alumina nano-particles. ^[59-63]

WATER-IN-DIESEL AND OXYGENATED EMULSION FUEL:

Pollutants emitted from diesel engines, especially nitrogen oxides and particulate matter, which can be detrimental to human health and to the ecological environment, attract much research interest. A further promising approach to reduce PM emissions by modifying the fuel composition involves the addition of oxygenated compounds to the normal diesel fuel. Fuel additives and blends have been investigated to limit the increase in PM emissions that often accompanies the reduction in NO_X (e.g. in combination with EGR). Oxygen can be added to the fuel bound to various types of oxygen containing compounds including ethers, alcohols, carbonates, acetates glycols and esters have been tested in engines to determine the effects of oxygenates on exhaust emissions. Oxygenates are range from light molecules such as ethanol to heavy methyl esters of vegetable oils with up to 20 carbon atoms. There have been many studies that investigate how each of these might influence exhaust emissions. While these studies used a variety of test engines, testing cycles and diagnostic methods, they consistently found a significant reduction of particulate emissions that has been correlated to the amount of oxygen added ^[65]. However, the conclusions differ related to the significance of the type of oxygenate used ^[64-66], An experimental and numerical investigation conducted, ^{[67, 69]} on the influence of fuel structure and of fuel molecule bound oxygen on soot formation and oxidation processes within laminar diffusion flames, showed the influence of the addition of the oxygenated compound dimethyl ether (DME) to the base fuels (ethylene and ethane). The oxygenated fuel inhibits the particle growth and lowers the particle number. The results point out that in DME containing flames the soot oxidation begins before the OH-radical zone in the flame, which indicates the presence of an additional soot oxidation mechanism with respect to that of the base fuel without oxygen. The influence of the addition of oxygenated hydrocarbons to diesel fuels has been studied ^[68].

COMMERCIAL AVAILABLE OF EMULSION FUEL:

In spite of some difficulties, certain emulsion fuels have been translated into commercial products, available in the market for use. Some commercial emulsion fuel are listed in Table [2]. We believe that we have successfully overcome all of these. Unlike any other technology, we can cost-effectively emulsified diesel fuel, kerosene and heavy fuel oil (HFO) with no required modification to equipment.

Table 2 : Commercial available of emulsion fuel.

Sr. No	Fuel	Commerical name	Company name
1	Diesel	PuriNOx	Lubri-zol
2	Diesel	Aquazole	TotalFinaElf
4	Diesel	Aquadiesel	Shell
5	Diesel	Proformix	Chevron
6	Diesel	E-diesel	Singapore Emulsion Fuel Pte Ltd
7	Kerosene	E-kerosene	Singapore Emulsion Fuel Pte Ltd
8	Heavy oil	MSAR®:	Ecostar Co., Ltd.
9	Heavy oil	PENTOMuls®	PENTOMuls

ADVANTAGES OF DIESEL/WATER EMULSION:^[^{2, 3, 6]}

· It has all the advantages of diesel as a compression ignition fuel while achieving reductions in the concentration of diesel’s major regulated pollutants: NOx and particulates

· It doesn’t affect the concentration of unregulated pollutants such as aldehydes, ketones and PAHs

· Switching from standard diesel to diesel/water emulsion requires no modifications to the engine or fuel injection system, independent of the engine’s age and technology

· Since standard diesel is used as the base fuel, the manufacturing of the diesel/water emulsion requires no alterations to the refining process, distribution network and storage facilities

· Standard tap water can be used in the emulsion, instead of distilled water, which reduces preparation costs

· The presence of water increases the flash point of the emulsion by ~ 40ºC which, in turn, increases the safety of the mixtures storage facilities, operators and drivers

· It gives slightly better combustion efficiency which may, in principle, reduce fuel consumption and CO₂

· Owing to the emulsification many kinds of the waste oils, from machine and food, can be recycled as the useful fuels in many forging.

DISADVANTAGES OF DIESEL/WATER EMULSION:^[^6,70]

· It is more expensive than standard diesel fuel.

· The presence of water in the diesel/water emulsion affects engine performance by reducing engine torque by up to 10%; this may require adjustment of the fuel delivery which, however, will increase fuel consumption

· Careful consideration should be given to the effect of the water present in the mixture on engine wear and lubricant performance.

· To prevent long-term stratification of the diesel/water emulsion a pump may have to be installed in the storage tank to re-circulate the mixture and prevent water separation at the bottom of the tank. An alternative and probably simpler method is to lower inside the tank the aspiration tube which is connected to the distributor pump.

SUMMARY:

When one looks at the recent history and current events, it still suggests that the fuels of the foreseeable future will still be gasoline and diesel, but improved, cleaner burning versions. These cleaner fuels will produce minimal emissions. Crude oil supplies tend to be more plentiful than estimated due to technology improvements. In addition, the technology and economic hurdles to convert other alternative energy sources into diesel and gasoline-like fuels continues to improve. The water emulsification has the potential to improve significantly the thermal efficiency and to suppress the formation of thermal NO, PACs, soot and carbonaceous residue, the practical combustion applications. The advent of the innovative emulsifier is opening up a new perspective for emulsion fuels. Further experiments are recommended to be continued for optimizing the emulsion formulation in terms of water content and internal structure of emulsion for various properties of base fuel and types of combustors. Water emulsification causes the same order of reduction of soot yielded in the spray flame and the droplet flame under micro-gravity. It would be significant to elucidate the basic mechanism of soot formation common to both flame. The fire resistant nature of emulsion is also important and interesting from the practical point of view. Experimental investigation is required to identify the dominant mechanism responsible for these unique properties

REFERENCE:

1. Abu-Zaid, M., “Performance of Single Cylinder Direct Injection Diesel Engine Using Water Fuel Emulsions,” Energy Converse. Manage. Vol. 45, No. 5, 2004, pp. 697–705.

2. Barnaud, F., Schmelzle, P., and Schulz, P., “Aquazole: An Original Emulsified Water-Diesel Fuel for Heavy Duty Applications,” Society of Automotive Engineerers, Inc., 2000-01-1861, pp. 95–101.

3. Harbach, J. and Agosta, V., “Effects of Emulsified Fuel on Combustion in a Four-Stoke Diesel Engine,”J. Ship Res, Vol. 35, No. 4, 1991, pp. 356–363.

4. Tsukahara, M. and Yoshimoto, Y., “Reduction of NOx, Smoke, BSFC, and Maximum Combustion Pressure by Low Compression Ratio in a Diesel Engine Fueled by Emulsion Fuel,” International Congress and Exposition, Detroit, 1992, pp. 71–77.

5. Law, C. K., “A Model for the Combustion of Oil/Water Emulsion Droplets, “Combust. Sci. Technol., Vol. 17, Nos. 1 and 2, 1977, pp. 29–38.

6. Anna Lif, Krister Holmberg, Water-in-diesel emulsions and related systems, Advances in Colloid and Interface Science 123–126 (2006) 231–239.

7. Nadeem M., C. Rangkuti, K. Anuar, M. Haq, I. B. Tan and S. Shah, Diesel engine performance and emission evaluation using emulsified fuels stabilized by conventional and gemini surfactants, Fuel, Volume 85, Issues 14-15, October 2006, Pages 2111-2119.

8. Samec, N., B. Kegl, and R.W. Dibble, Numerical and experimental study of water/oil emulsified fuel combustion in a diesel engine, Fuel, Volume 81, Issue 16, 2002, Pages 2035-2044.

9. Park JW, KY. Huh, JH. Lee, Reduction of NOx, smoke and brake specific fuel consumption with optimal injection timing and emulsion ratio of water-emulsified Diesel. Proc Inst Mech Eng 2001; 215:83–93.http.dx.doi.org/10.1243/0954407011 525476

10. Park JW, Huh KY and Park KH., 2000, Experimental study on the combustion characteristics of emulsified Diesel in a rapid compression and expansion machine. Proc Inst Mech Eng; 214(Part D):579–86.

11. DOE/EIA (Department of Energy/Energy Information Agency) Annual Energy Outlook, DOE, Washington, DC. (2008).

12. Stone, R., “Introduction to internal combustion engines”.: Society of Automotive Engineers (SAE), Warrendale, PA, 1999.

13. Avinash Kumar Agarwal, Biofuels (alcohols and biodiesel) applications as fuels for internal combustion engines‟ Department of Mechanical Engineering, Indian Institute of Technology, Kanpur-208 016, India November 2006.

14. Jiafeng Sun, Jerald A. Caton, Timothy J. Jacobs „Oxides of nitrogen emissions from biodiesel-fuelled diesel engines, Progress in Energy and Combustion Science, 36, 677-695 (2010). http.dx.doi.org/10.1016/j.pecs.2010.02.004

15. Dryer, F.L. Water Addition to Practical Combustion Systems-Concepts and Applications. Proc.Combust.Inst. Vol.16, pp. 279-295, 1976.

16. Sjorgen, A.: Burning of Water-in-Oil Emulsions, Proc. Combust. Inst., Vol.16, pp. 297-305, 1976.

17. Jacques,M.T. et al.: The Combustion of Water-in-Oil Emulsions and The Influence of Asphaltene Content, Proc. Combust. Inst., Vol.16,pp. 307-319, 1976.

18. Hall, R.E.: The Effect of Water/Residual Oil Emulsions on Air Pollutant Emissions and Efficiency of Commercial Boilers, Journal of Engineering for Power, Transactions of ASME October,pp. 425-433, 1976

19. Jacques, M.T.: Transient Heating of a Emulsified Water-in-Oil Droplet, Combustion and Flame, Vol.29, pp. 77-85, 1977.

20. Birchley, J.C.and Riley, N.: Transient Evaporation and Combustion of a Composite Water-Oil Droplet, Combustion and Flame, Vol. 29, pp. 145-165, 1977.

21. Law,C.K.: AModel forthe Combustion of Oil/Water Emulsion Droplets, Comb.Sci. And Tech., Vol. 17, pp. 29-38, 1977.

22. Weatherford Jr., W.D., et al.: Army Fire-Resistant Diesel Fuel, SAE Technical PaperSeries, No. 790926, 1979.

23. Kadota, T.and Yamasaki, H.: Recent Advances in the Combustion of Water Fuel Emulsion, Progress in Energy and Comb. Sci., Vol. 28, pp. 385-404, 2002.

24. Kufferath, A., et al.: Continuous Generation and Air-Assisted Atomization of Fuel Oil-Water-Emulsions, Comb. Sci. and Tech., Vol. 148, pp. 17-26, 1999

25. Lin, C.Y., Pan, J.Y., 2001. The effects of sodium sulfate on the emissions characteristics of an emulsified marine diesel oil-fired furnace. Ocean Eng. 28 (4), 347–360

26. Musculus, M. P., Dec, J. E., Tree, D. R., Ryan III, T. W., Matheaus, A. C., Daly, D., and Langer, D.. Effects of water-fuel emulsions on spray and combustion processes in a heavy-duty DI diesel engine. SAE 2002-01-2892. SAE Power train & Fluid Systems Conference & Exhibition, San Diego, CA, 2002, October 21–24.

27. Lin C-Y, Wang K-H. Fuel 2003; 82:1367.

28. Lin C-Y, Wang K-H. Fuel 2004; 83:507.

29. Lin C-Y, Wang K-H. J Environ Sci Health Part A Toxic/Hazard Subst Environ Eng 2004; 39:1345.

30. Lin C-Y, Wang K-H. Energy Fuels 2004; 18:477.

31. Lin C-Y, Wang K-H. Fuel 2004;83:537

32. Holmberg K, Jönsson B, Kronberg B, Lindman B. Surfactants and Polymers in Aqueous Solution. 2nd ed. Chichester: Wiley; 2003. p. 139.

33. Gillberg G, Friberg S. Symp on Evaporation and Combust of Fuel Droplets, Aug 29–Sep 3 1976, vol. 21; 1976. p. 731.

34. Ahmad I, Gollahalli SR. J Propuls Power 1994; 10:744.

35. Neuma de Castro Dantas T, da Silva AC, Neto AAD. Fuel 2001; 80:75.

36. Adiga KC. Energy-Sources Technology Conference and Exhibition, Jan 26–30 1992, vol. 41. New York: ASME; 1992. p. 9.

37. Adiga KC, Shah DO. Combust Flame 1990; 80:412.

38. Qingguo L, Gollahalli SR. Proceedings of the Energy-Sources Technology Conference, Jan 23–26 1994, vol. 57. New York, NY, USA: ASME; 1994. p. 15.

39. Lee, G.W. and Tadros, T.F. (1982) Colloids Surf. 5: 105–115.

40. Khalilia .a, shekarriz m. , pirzadeh y. ,haji ali akbarif ,yar kazemifar a. ,taghipoor s. effect of diesel nanoemulsion fuel on reduction of exhaust pollutants in comparison with conventional fuel petroleum research; spring 2012; 22(69);42-52

41. Mudhafar Kareem Abdullah, A. Bulent Koc, Exhaust emissions of a diesel engine fueled with Water-biodiesel-diesel nanoemulsions, An ASABE Meeting Presentation Paper Number: 1111195,

42. A. M. Al-Sabagh,Mostafa M. Emara , M. R. Noor El-Din,W. R. Aly, Preparation of Water-in-Diesel Fuel Nanoemulsions Using High-Energy Emulsification Method and a Study of Some of Their Surface Active Properties , Journal of Dispersion Science and Technology(2012), 33:7, 970-976

43. Ruckenstein, E. and Chi, J.C. (1960) J. Chem. Soc., Faraday Trans., 71: 2.

44. Agarwal, A. K. 2007. Biofuels (alcohols and biodiesel) applications as fuels for internal combustion engines. Progress in Energy and Combustion Science33(3):233-271

45. Landfester, K., Willert, M., and Antonietti, M. (2000) Macromolecules, 33: 2370.

46. Fawzi A. Al-Amrousi, Ahmed M. Al-Sabagh and Magda M. Osman Physicochemical characterization of emulsion fuel from fuel oil-water-charcoal and surfactants Fuel 1996 Volume 75 Number 10.

47. Vaghela kalpesh investigation of suitability of wood charcoal as an alternative fuel for diesel engine international journal of advanced engineering research and studies vol. I/ issue ii/january-march, 2012/48-50

48. vaghela kalpesh, dabhi shyam,review of charcoal-diesel slurry: an Alternative fuel for compession ignition engine, international journal of advanced engineering research and studies vol. I/ issue iii/april-june, 2012/143-147

49. Sayel M. Fayyad, Suleiman Abu-Ein, Ghazi Al-Marahleh, W aleed Al-Momani, Muntaser Al-Momani, Zaid Abulghanam, Omar Badran and Taiseer Abu-Rahmah, Experimental Emulsified Diesel and Benzen Investigation, Research Journal of Applied Sciences, Engineering and Technology 2(3): 268-273, 2010.

50. http://www.swri.edu/9what/releases/Pre1996/fireresi.htm

51. http://web.mit.edu/invent/iow/gunnerman.html

52. Cherng-Yuan Lin, Shiou-An Lin, Effects of emulsification variables on fuel properties of two and three-phase biodiesel emulsions, Fuel 86 (2007) 210-217 doi:10.1016/j.fuel.2006.06.007

53. C.-Y. Lin, H.-A. Lin / Engine performance and emission characteristics of a three-phase emulsion of biodiesel produced by per oxidation Fuel Processing Technology 88 (2007) 35–41 doi:10.1016/j.fuproc.2006.07.008

54. T. Kandasamy kannan and marappan rakkiyanna gounder, thevetia peruviana, biodiesel emulsion used as a fuel in a single cylinder diesel engine reduces nox and smoke thermal science, year 2011, vol. 15, no. 4, pp. 1185-1191.

55. Mudhafar Kareem Abdullah, A. Bulent Koc 2011 ASABE Annual International Meeting Exhaust emissions of a diesel engine fueled with water-biodiesel-diesel nanoemulsions An ASABE Meeting Presentation Paper Number: 1111195

56. Masjuki H, Abdulmuin MZ, Sii HS, Chua LH, Seow KS. J Energy Heat Mass Transfer 1994;16:295.

57. Kinoshita E, Hamasaki K, Jaqin C, Takasaki K. SAE Spec Publ 2004;SP-1887:15.

58. Jamil Ghojel, Damon Honnery, Khaled Al-Khaleefi, “Performance, emissions and heat release characteristics of direct injection diesel engine operating on diesel oil emulsion”, Laboratory for Turbulence Research in Aerospace and Combustion, Department of Mechanical Engineering, Monash University, Melbourne, Australia

59. J. Sadhik Basha and R. B. Anand,Role of nanoadditive blended biodiesel emulsion fuel on the working characteristics of a diesel engine, journal of renewable and sustainable energy 3, 023106 (2011)(alumin)

60. j. Sadhik Basha & R. B. Anand (2011): An Experimental Study in a CI Engine Using Nanoadditive Blended Water–Diesel Emulsion Fuel, International Journal of Green Energy, 8:3, 332-348

61. Mu-Jung Kao, Chen-Ching Ting, Bai-Fu Lin, and Tsing-Tshih Tsung, Aqueous Aluminum Nanofluid Combustion in Diesel Fuel Journal of Testing and Evaluation, Vol. 36, No. 2 Paper ID JTE100579

62. Mench, M. M., Yeh, C. L., and Kuo, K. K., “Propellant Burn-ing Rate Enhancement and Thermal Behavior of Ultra-Fine Aluminum Powder (Alex),”Proceedings of the 29th International Annual Conference of ICT, Karlsruhe, Federal Republic of Germany, 1998, pp. 30/1–30/15.

63. Kao, M. J., Lin, B. F., and Tsung, T. T., “The Study of High-Temperature Reaction Responding to Diesel Engine Performance and Exhaust Emission by Mixing Aluminum Nano-fluid in Diesel Fuel,” 18th Internal Combustion Engine Symposium Jeju, Korea, 2005.

64. Litzinger T.; Stoner M.; Hess H.; Boehman A.: Effects of oxygenated blending compounds on emissions from a turbocharged direct injection diesel engine, International Journal on Engine Research, IMechE, 2000, Vol 1, No 1, 57-70

65. Lombaert K.; Le Moyne L.; Tardieu de Maleissye J.; Amouroux J.: Analysis of diesel particulate: influence of air-fuel ratio and fuel composition on polycyclic aromatic hydrocarbon content, International Journal of Engine Research, IMechE, 2002, Vol 3, No 2, 103-114

66. Miyamoto N.; Ogawa H. et al.: Improvement of diesel combustion and emissions with addition of various oxygenated agents to diesel fuels, SAE Paper 962115, 1996

67. Miyamoto N.; Ogawa H.; Nurun N.; Obata K.; Arima T.: Smokeless, Low NOX , High Thermal Efficiency, and Low Noise Diesel Combustion with Oxygenated agents as main Fuel, SAE Paper 980506, 1998

68. Curran H.; Fisher E.; Glaude P.; Marinov M.; Pitz j.; Westbrook C.; Layton D. et al.: Detailed Chemical Kinetic Modeling of Diesel Combustion with Oxygenated Fuels, SAE Paper 2001-01-0653, 2001

69. Spreen B.; Ullman T. et al.: Effects of Cetane Number, Aromatics, and Oxygenates on Emissions from a 1994 Heavy-Duty Diesel Engine with Exhaust Catalyst , SAE Paper 950250, 1995.

70. Barnaud F, Schmelzle P, Schulz P. SAE Spec Publ 2000;SP-1551:95.

Received on 27.06.2013 Accepted on 15.08.2013

Research J. Science and Tech 5(4): Oct.- Dec.., 2013 page 396-403

Sr.no.	Date	Patents on emulsion fuel
1	24 June 1931	Joseph A. Vance filed for a U. S. Patent
2	26 August 1935	Autoxygen Inc. a New York corporation applied for a patent.
3	8 February 1943	The Bristol Aeroplane Company Limited Filed a patent
4	28 January 1944	Sol B. Wiezer and Vaman R. Kokatnur applied for a patent.
5	29 January 1951	Bernard Magui and Andre Gerard, applied for a U. S. patent
6	1 March 1971	Eric C. Cottell of Long Island N. Y. filed a patent.
7	20 September 1979	"Fire Resistant Diesel Fuel" Southwest Research Institute
8	5 October 1987	Zugol AG applied for patent
9	17 May 1988	Microemulsion fuel system, Edward A. Hazbun et al Filed a patent
10	3 May 1991	Rudolf W. Gunnerman filed a U. S. patent
11	18 June 1991	Super heavy oil emulsion fuel Moriyam Filed a patent
12	21 sep 1993	Emulsion fuel engine Shimada et .al Filed a patent
13	11 May 1999	Multiple emulsion and method for preparing same Hercillion Rivas Filed a patent
14	9 May 2000	Methods for adding value to heavy oil Motasimur Rashid khan Filed a patent
15	22May 2001	Combustion of nano-partitioned fuel Ahern Filed a patent
16	2 October 2001	Water /oil emulsion fuel Hirotsugu Nohara Filed a patent
17	2001	California Air Resources Board (ARB) verifies PuriNOx as Alternate diesel fuel first emulsion fuel brand.
18	25 July 2002	Microemulsion fuel additive, Richard H.Hicks Filed a patent
19	9 September 2002	California Air Resources Board (ARB) verifies Aquazole as Alternate diesel fuel.
20	20 Jan 2003	European Emulsion Fuels Manufacturers Association (EEFMA) formed
21	26 June 2008	Multiple polydispersed fuel emulsion Brunelle Filed a patent
22	14 July 2009	Manufacture method of water emulsion fuel Hiroyasu Sato Filed a patent
23	12 Jan 2010	High stability fuel composition. Coleman Filed a patent
24	5 February 2010	The opening of Asia's First Clear Nano-Emulsion Diesel Plant Opened by Singapore Emulsion Fuel Ltd.

ADVANTAGES OF DIESEL/WATER EMULSION:[2, 3, 6]

DISADVANTAGES OF DIESEL/WATER EMULSION:[6,70]

ADVANTAGES OF DIESEL/WATER EMULSION:^[^{2, 3, 6]}

DISADVANTAGES OF DIESEL/WATER EMULSION:^[^6,70]