Archive | 2021
Relative Change in SI Engine’s Emission and Performance Parameters Using New Locally Made Octane Enhancer
Abstract
In this study, a new gasoline Octane enhancer was made in Al-Doura refinery in Baghdad and was used with the Iraqi pool gasoline. The main objective of this study was to find an Octane booster to the low Octane Gasoline produced by Al-Doura refinery that does adversely affect its chemical, physical or combustion properties. This additive was then added to gasoline in different percentages (2.5% till 15% Vol) and the blend’s properties e.g. calorific value, density, Octane number (RON and MON), gum content, sulfur content were measured. These blends were then tested against the performance of the original pool gasoline using previously calibrated and tested software. The relative change in the engine performance was then observed and compared. It was found that the octane number of gasoline significantly improved after addition of the additive, its gum content decreased, its calorific value decreased while the sulfur content was slightly increased. No major change in the engine performance was noticed except for the decrease in peak cylinder temperature and the sulfur dioxide and nitrogen oxides level at 2.5% then increased with additives. Keyword: Gasoline antiknock additives, Octane number enhancing, TEL phase out, engine performance, engine emission. No.16 Journal of Petroleum Research & Studies (JPR&S) E10 Introduction The properties of gasoline are influenced by the origin of the crude oil, the refinement processes and the presence of additives, which are added for improving the performance and reducing the emissions of automotive vehicles [1–4]. The addition of oxygenates to gasoline became widespread after the elimination of the tetraethyl lead compounds [5]. Brazil was one of the pioneers in the removal of this compound through its substitution for alcohol (ethanol). The improved combustion achieved by using oxygenated additives (alcohols and tertiary ethers) in place of aromatic compounds grows interest in the former [6]. The composition of a gasoline can influence the emission of organic compounds. Gasolines containing high proportions of aromatic hydrocarbons such as benzene, toluene, xylenes, and olefins produce relatively high concentrations of reactive hydrocarbons [7, 8]. The occurrence of knock in internal combustion engines strict limitations on their efficiency and fuel economy. Knock may be minimized by engine design and adjustment of operating conditions or by the use of high octane gasoline. The required levels of antiknock quality in motor gasoline are obtained by modification of refinery processing and the blending of gasoline as well as by the use of antiknock additives. By far the most widely used additives for control of knock were the lead alkyls [9]. Antiknock agents – is a gasoline additive that works to reduce engine knocking while trying to increase the octane rating of the fuel. The mixture of air and gas in a traditional car engine has a problem with igniting too early and when it does, it causes a knocking noise. Some of the antiknock agents are: Tetra-ethyl lead, Methylcyclopentadienyl manganese tricarbonyl, Ferrocene, Iron pentacarbonyl, Toluene, Isooctane [10]. Refiners add tetraethyl lead (TEL) and tetramethyl lead (TML) to gasoline to increase octane. In most situations, adding lead is the least expensive means of providing incremental octane to meet gasoline specifications. At sufficiently high levels, addition of lead can increase octane as much as 10 to 15 control octane numbers [11]. No.16 Journal of Petroleum Research & Studies (JPR&S) E11 Alcohols, in comparison, burn nearly pollution-free. Alcohols already contain oxygen integral with the fuel, which can lead to a more homogenous combustion. Alcohols burn with a faster flame speed than gasoline, and they do not contain additional elements such as sulphur and phosphorus [12]. Several researchers tested many additives to improve the knocking characteristics of gasoline. Poulopoulos et.al [13] examined the effect of using MTBE as an additive to gasoline upto 11% into gasoline on the automotive’s exhaust emissions especially CO, HC and MTBE before and after the 3-way catalyst. They reported that the addition of MTBE into gasoline resulted in a decrease in CO and HC emissions only at high engine loading. During cold-startup of the engine, MTBE, HC, CO emissions were significant and increased with MTBE addition into fuel. At the catalytic converter outlet MTBE was detected when its concentration in fuels was greater than 8% and only as long as the catalytic converter operates at low temperatures. Osman et.al [14] also found the same effect on the exhaust emissions on his test conducted on Opel 4-cylinder engine. They used higher concentrations of MTBE e.g. 10, 15 and 20% by volume. Their results have shown that MTBE blends gave slightly better engine performance than the unleaded gasoline as evidenced by the power output. Further, they reported better carbon monoxide and hydrocarbon emissions for all MTBE blends tested than unleaded gasoline. A higher carbon dioxide exhaust emission of the blends than the unleaded gasoline also confirms their better combustion. The 20 vol % MTBE blend gave the lowest carbon monoxide and hydrocarbon emissions of all blends used. Another additive to improve the knocking behavior of gasoline tested was ethanol. Koc et.al [15] studied the effects of unleaded gasoline (E0) and unleaded gasoline–ethanol blends (E50 and E85) on engine performance and pollutant emissions in a single cylinder four-stroke sparkignition engine at two compression ratios (10:1 and 11:1). The engine speed was varied from 1500 to 5000 rpm at wide open throttle (WOT). They reported that ethanol addition to unleaded gasoline increased the engine torque, power and fuel consumption and reduced carbon monoxide (CO), nitrogen oxides (NOx) and hydrocarbon (HC) emissions. They also found that ethanol– gasoline blends suppressed knocking at higher compression ratios. No.16 Journal of Petroleum Research & Studies (JPR&S) E12 Gouli et.al [16] studied the effect of two different oxygenates namely Furan Derivatives and Pcresol on the engines emissions. They reported that these additives were very effective as antiknock compounds, reduced the aromatic content of the exhaust without affecting the gasoline properties. Besides the many other chemicals tested as antiknock agents e.g. ETBE addition [17], methanol [18] hydrogen as supplement fuel [19] and others. The main problem with the use of oxygenates is its rusting effect on the fuel supply system. Hence, there was urgent need for change in the materials used for fuel supply in the vehicle. This instilled the quest for finding an alternative from within the petroleum refinery process that can solve this issue and improve the antiknock behavior of gasoline. This agent was thought of to be locally manufactured and should not harm the engine performance and emission characteristics. This locally made improve was made in AlDoura Oil Refinery in Iraq. Experimental work The first part of this research was related to the manufacturing of the additives. Al-Doura gasoline pool in Baghdad contains 45% Reformate, 25% Power Former, and 30% light Naphtha, the antiknock additives was prepared from reformate fractionation by the following procedure: Reformate was first distilled by simple distillation unit, and the distill (180-E.Bp) was collected. Then reformate cut “R3” was added to gasoline pool (RON =84.5) in six ratios (2.5, 5, 7.5, 10, 12.5 and 15 %volume) with continuous stirring. After preparation of the blends, gasoline pool, and all blends were tested using Grabner IROX 2000 Portable Gasoline Analyzer shown below in Figure (1). No.16 Journal of Petroleum Research & Studies (JPR&S) E13 Fig. (1)Grabner IROX 2000 Portable Gasoline Analyzer. The device used several ASTM test methods for gasoline properties [20]. As an example ASTM D4814 Standard Specification for Automotive Spark-Ignition Engine Fuel, ASTM D2699 Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel and ASTM D2700 Standard Test Method for Motor Octane Number of Spark-Ignition Engine Fuel. Further, the blend mixture’s RON was measured using the Cooperative Fuel Research (CFR) engine. This single cylinder engine is used extensively throughout the world for testing, research, and instruction in the performance of fuels and lubricants for the internal combustion engine. Finally, the effect of these mixtures on the engine’s performance was studied using wellestablished and calibrated software called Diesel-RK. The study was conducted on Ricardo E6/T, spark ignition, single cylinder, four-stroke, water-cooled variable compression engine. The engine speed was varied from 750 rpm to 3000rpm at 250rpm increment. The equivalence ratio was fixed at the stoichiometric and angle of ignition to be 20 before top dead center (bTDC). The compression ratio was fixed at 8.5:1 to simulate most of the vehicles used in Iraq. The engine has bore = 76.2mm, stroke 111.125mm, inlet valve opens at 9 before TDC, closes at 36 after bottom dead center (aBDC), the exhaust valve opens at 41before BDC and closes at 8 aTDC. The parameters studied for the sake of this study were: brake power (kW), brake specific No.16 Journal of Petroleum Research & Studies (JPR&S) E14 fuel consumption (kg/kW-hr), maximum cylinder pressure (bar), nitrogen oxides (ppm) and sulfur dioxide (g/kW-hr) levels in the exhaust. Brake Power is the power actually available at the engine shaft. It is usually obtained from measurement of the engine torque when a driving against a brake and it is given by the following formula: