Combustion Performance of Palm-Diesel Blends in an Oil Burner

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1 Combustion Performance of Palm-Diesel Blends in an Oil Burner * a,b MOHAMAD SHAIFUL ASHRUL ISHAK, a MOHAMMAD NAZRI MOHD. JAAFAR, a WAN ZAIDI WAN OMAR a Department of Aeronautics, Automotive and Ocean Engineering, Faculty of Mechanical Engineering. Universiti Teknologi Malaysia, UTM Skudai, Johor, MALAYSIA. b School of Manufacturing Engineering, Universiti Malaysia Perlis. PO Box 77, Pejabat Pos Besar, Kangar, Perlis, MALAYSIA. * mshaiful@unimap.edu.my Abstract: - The problems of global warming and the unstable price of petroleum oils have led to a race to develop environmentally friendly biofuels, such as palm oil diesel or ethanol derived from corn and sugar cane. Biofuels are a potential replacement for fossil fuel, since they are renewable and environmentally friendly. This paper evaluates the combustion performance and emission characteristics of Refined, Bleached, and Deodorized Palm Oil (RBDPO)/diesel blends B5, B10, and B15 by volume, using an industrial oil burner. Emissions released were measured at the exit to the chamber using a gas analyser. The results show that the B15 blend generated the lowest emission with a 69% reduction in carbon monoxide (CO), 44% in oxide of nitrogen (NO X ) and 34% in unburned hydrocarbon compared to conventional diesel fuel (CDF). However, the temperature profile for B15 is the lowest implying that the heat released is much lower than the other blends. Biodiesel blend of B5 showed the highest temperature profile besides diesel, which gave the highest temperatures. Key-Words: - Combustion, Oil Burner, Biofuel, RBDPO, emission constituents 1 Introduction The continuing reduction in known petroleum reserves and the continuously increasing demand for energy is making renewable energy resources more attractive. One possible candidate to replace diesel fuels in diesel engines is biodiesel. The major advantage that biodiesel has over gasoline and petroleum diesel is its environmental friendliness. Biodiesel burns better compared to petroleum diesel in terms of regulated pollutants, and biodiesel has better efficiency than gasoline [1, 2]. On the other hand, biodiesel has lower energy content compared to the conventional diesel fuel (CDF). Biodiesel derived from vegetable oils also displays great potential to replace petroleum diesel in compression-ignition engines. Biodiesel nowadays is mainly made from soybean, rapeseed and palm oils. Economic benefits of biodiesel industry would include value added to the feedstock, increased number of rural manufacturing jobs, increased income taxes and rural investments in plant and equipment. The production and utilization of biodiesel are also facilitated, firstly through the agricultural policy of subsidizing the cultivation costs of non-food crops. Secondly, biodiesel is exempted from the oil tax in most countries. The European Union accounted for nearly 89% of all biodiesel production worldwide in In the future, the United States is expected to become the world's largest single biodiesel market, accounting for roughly 18% of world biodiesel consumption, followed by Germany [2]. 2 Biodiesel Blends Effect on Emissions Generally, biodiesel is an oxygenated fuel with low cetane numbers. Even though this property implies lower flame temperatures, hence generating higher NO X emissions from the fuel NO X pathway, few researchers found the enigma of increased NO X emissions when utilizing biodiesel fuels. This paper present an introductory method to comprehend the combustion characteristics of palm based biodiesel when combusted in open air [3]. Thermal, prompt and fuel NO X are the main pathways that contribute to the overall NO X emissions based on Zeldovich Mechanism [4]. The main contributor to NO X emissions is through the thermal NO route formed in the combustion ISBN:

2 chamber. This type of NO X is generally formed during fuel combustion with atmospheric air since air consists primarily of oxygen and nitrogen [4, 5]. Studying the temperature profiles of combustion flames can be helpful in determining the formation of NO X during the combustion of biodiesel. In principle, there are two methods to control the formation of NO X emission in an oil burner: those that retard its formation [8-11] and those that destroy it from the products of combustion [11-13]. The technique that retards NO X formation involves modifications to the burner configurations or operating condition to accommodate the usage of biodiesel instead of diesel. Several earlier tests in liquid spray combustion on palm biodiesel blends to determine its usage as alternative fuel [3, 14, 15] found that biodiesel blends with lower palm oil contents such as B5 and B10 performed quite satisfactorily as compared to diesel. However, the droplet size is larger and the combustion temperature drops slightly [15]. The current study extends these researches further to include combustion testing. 4 Research Methodology This experiment investigates the combustion performances of biodiesel blends compared to diesel fuel at different equivalent ratios. This experiment was conducted by using different types of biodiesel blends derived from RBDPO and diesel fuel at different equivalent ratios. Equivalent ratios are defined as the actual airfuel ratio to the stoichiometric air-fuel ratio. This experimental test rig set-up for the combustion test is shown in Figure 1. The burner and combustion chamber is an open ended type, placed horizontally on a fixed structure. For all tests, the exhaust sampling probe is mounted at the end of the pipe. The model of the gas analyzer used in these tests was KM9106 Quintox. The combustion chamber was made from rolled 2 mm thick mild steel with 8 cm external with cast cement to insulate the combustion chamber. Fig. 1 Schematic of the experimental set-up 3 Results and Discussions The experimental tests were run for three different equivalent ratios of 0.8, 1.0 and 1.4. The combustion tests were conducted to determine the emissions concentrations from the burner system. The emission characteristics will indicate the suitability of the biodiesel blend as the replacement fuel for diesel. The emission profile is essential to make sure less harm to the environment if diesel is replaced with bio-diesel. The emission results obtained from the combustion of biodiesel blends and diesel are discussed in the following sections. ISBN:

3 3.1 Carbon monoxide (CO) Carbon monoxide, CO is a light toxic gas that can form during incomplete combustion. CO is colorless, odorless and extremely harmful to the respiratory system. Over exposure to CO can cause headache, dizziness and sometimes death. Thus, it is important to measure CO emissions to understand the impact to the environment due to bio-diesel combustion. Figure 2 shows the CO emissions for diesel and Biodiesel blends at different equivalent ratios. Generally the CO emission reduces as the equivalent ratio approaches 1, then increase again past EQR 1. The CO emissions of Biodiesel blends are well below the level of diesel fuel, with the emission of B15 dropping to 8 ppm from 28 ppm for diesel at EQR 1. During combustion process, most of the carbon reacts to form carbon dioxide, however some of the carbon stays in the intermediary stage as carbon monoxide. 3.2 Oxide of Nitrogen (NO X ) Oxides of nitrogen or NO X, is the generic term for a group of highly reactive gases, which contain nitrogen and oxygen in various amount and chemical configurations. Most of the nitrogen oxides are colourless and odourless. Figure 3 shows the NO X emissions from the combustor burning diesel and Biodiesel blends at various equivalent ratios. This shows that NOx emission is lower for Biodiesel blends compared to CDF, with B15 producing 42 ppm at EQR 1, B10 producing 57 ppm and B5 producing 59 ppm, while CDF produced 78 ppm. Similar results were obtained for other equivalent ratios. NO X generally increases with increasing equivalent ratio up to EQR 1, then decreases with equivalent ratio past EQR1. This could be explained by the fact that oxides of nitrogen mainly formed by fuel combustion at high temperature, which in these cases occur at equivalent ratio of 1.0 which is the most efficient combustion condition. The result in Figure 3 also disobeys the theoretical values where the plot should go down rapidly almost like the after equivalent ratio of 1.0. But in this case, the level of NO X emission increases with equivalent ratio. This is due to contaminants which were left by earlier combustion inside the combustion chamber that influence the gas analyser readings. It is impossible to clean the combustion chamber after every Biofuel blend testing because the contaminants were trapped and plugged to the inner chamber wall between the stripped metal pieces. 3.3 Unburned Hydrocarbons (UHC) Unburned hydrocarbons, UHC, consist of fuels that exist in the form of vapour or droplets. The presence of UHC manifested itself in the exhaust by thick sooty smog. This is mainly due to incomplete combustion. Figure 4 shows the emission of UHC for diesel and biodiesel blends at different equivalent ratios. The emission of UHC for all biodiesel blends is lower than the diesel fuel, with B15 recording the lowest UHC emissions. At equivalent ratios lower than 1, the UHC decreases with the increase of the equivalent ratio, reaching lowest values at EQR 1. Thereafter, the UHC increases with increasing equivalent ratios. Fig. 2 Carbon Monoxide emissions from combustions of CDF and ISBN:

4 Fig. 3 Nitrogen Oxides emission from combustions of CDF and Fig. 4 Unburned Hydrocarbon emissions from combustions of CDF and 4 Conclusion In this experiment, the behaviour of each emission is fairly distinguished at equivalent ratio 1.0. Let s take a look at B15 emission, due to its high palm oil content. It has 69% reduction of carbon monoxide, CO, 44% reduction of oxides of nitrogen, NO X and 34% of unburned hydrocarbon compared to diesel fuel. This shows significant amount in lethal gas reduction and shows positive improvement to the environment. Experiment done also show that B5 performs slightly better than the CDF due to its calorific value. Even so, the performance of B10 and B15 is still acceptable. From this study, it can be concluded that biodiesel is ready to hit the commercial market. Some of the biodiesels perform even better than the diesel such as B5. Acknowledgements The authors would like to thank the Ministry of Education of Malaysia & Research Management Center (project number: 01G60) for awarding a research grant to undertake this project. The authors would also like to thank the Faculty of Mechanical Engineering, Universiti Teknologi Malaysia for providing the research facilities and space to undertake this work. References: [1] Moser, B.R., Influence of Blending Canola, Palm, Soybean, and Sunflower Oil Methyl Esters on Fuel Properties of Biodiesel. Energy and Fuels, 2008: p [2] Sawarimuthu, S. and Jaafar, M.N.M., Performance of Various Biofuel Blends on ISBN:

5 Burner System. Jurnal Mekanikal, : p [3] Mantari, M.H.A.R. and Jaafar, M.N.M., Performance of Oil Burner System Utilizing Various Palm Biodiesel Blends. International Journal of Mechanical and Materials Engineering, (3): p [4] Lefebvre, A.H., Gas Turbine Combustion. 1990, New York: McGraw-Hill. [5] Lefebvre, A.H., Atomization and Sprays. 1978: Purdue University West Lafayette, Indiana, Taylor & Francis. [6] Stebler, H., Bouchoulos, K., Eberle, M.K., Geist, M., and Vlaskos, I., Reduction of NOx-emissions of a medium-speed DI Diesel engine using Miller system, exhaust gas recirculation, variable nozzle turbocharger and common rail fuel injection. International Congress in Combustion Engineering Proceedings, (4): p [7] Tat, M.E., Wang, P.S., Van Gerpen, J.H., and Clemente, T.E., Exhaust Emissions from an Engine Fueled with Biodiesel from High-Oleic Soybeans. Journal of The American Oil Chemists Society, (9): p [8] Eide, L.I. and Bailey, D.W., 60 (3),, Precombustion Decarbonisation Processes. Oil Gas Sci. Technol. - Rev. IFP, (3): p [9] Fukushima, S. and Suzukawa, Y., Eco- Friendly Regenerative Burner Heating System Technology Application and Its Future Prospects. NKK Tech. Rev., : p [10] Jaafar, M.N.M., Ishak, M.S.A., and Saharin, S., Removal of NOx and CO from a Burner System. Environ. Sci. Technol., : p [11] Jaafar, M.N.M., Modulated and Staged Low NOX Burner. Department of Fuel and Energy. PhD. 1997: University of Leeds, Leeds, United Kingdom. [12] Abul Hossain, K., Mohd-Jaafar, M.N., Mustafa, A., Appalanidu, K.B., and Ani, F.N., Application of Selective Non- Catalytic Reduction of NOx in Small-Scale Combustion Systems. Atmos. Environ., : p [13] Saharin, S. and Mohd-Jaafar, M.N., Emissions Reduction of an Oil Burner by Air Staging, in International Conference on Environment [14] Hasagaya, M.A.A., Jaafar, M.N.M., and Ishak, M.S.A., Investigation of oil burner combustion performance when utilizing palm biodiesel blends. International Review of Mechanical Engineering, (3): p [15] Abdul Halim, A.K., Jaafar, M.N.M., and Ishak, M.S.A., Bio-fuel atomizer design for micro-gas turbine. International Review of Mechanical Engineering, (4): p ISBN: