Investigations on compression ignition engine durability through long-term endurance study using low viscous biofuel blends

These days, biomass-based low viscous renewable biofuel is very much popular for internal combustion engine applications due to its unique features compared to other form of biofuels. In this present work, a comparative analysis has been carried out to investigate the suitability of waste biomass-based low viscous biofuel through long-term durability study. A 256 h of long-term endurance test as per Indian Standard: 10,000, Part IX-1980 standard has been conducted using 10% and 20% by volume of waste biomass-based biofuel in two different phases, and the tested results are compared with the results of conventional diesel fuel. During this long-term endurance study, the variations in performance, emissions and behaviours are observed before and after the 256 h of operation in both the phases. The long-term endurance test has degraded the engine components which has reflected in engine performance. The carbon deposit would play a vital role in lowering the engine performance. It has been evident that lubricant oil degradation is deteriorates the engine performance. Furthermore, the durability study has also reflected that the diesel engine emissions are extremely higher after the endurance test when compared to fresh engine. On the other hand, the carbon monoxide and unburned hydrocarbon emissions are lower in waste biomass-based biofuel operation except oxides of nitrogen emissions. This is due to the clean burning ability of biofuel which has shown remarkable combustion behaviour compared to diesel fuel. The long-term tribological test has shown that the kinematic viscosity and flash point of lubricating oil are reduced during endurance study and this has reflected more severe for diesel fuel when compared to waste biomass-based biofuel. The ash content for 20% of lemon peel oil is 19% higher than diesel fuel and 10% of lemon peel oil blend. Higher rate of oxidation has resulted in significant reduction in total base number of lubricating oil which reveals that the low viscous biofuel has higher lube oil degradation. It is also evident that wear of engine components is deteriorated the life of the engine along with lubricant oil degradation. Piston rings wear is more in the lubricant collected from 20% of lemon peel oil blend as compared other fuels. Finally, it has been concluded that the low viscous biofuel has poor resistance on diesel engine wear and this could be rectified before its application.

Graphic abstract

     

Study on the effect of exhaust gas-based fuel preheating device on ethanol–diesel blends operation in a compression ignition engine

Rapid depletion of fossil fuels and stringent emission regulations compel the scientific community to search for alternative energy sources for the internal combustion engines. Among many alternative biofuels, ethanol is getting worldwide attention for compression ignition engine either in the form of partial substitute or complete replacement for diesel fuel. Ethanol fuel has certain undesirable properties like poor flammability limit which results in cold starting issues and higher hydrocarbon emission which restricts their use in compression ignition engine. This issue can be easily overcome by preheating of ethanol fuel before it gets admitted inside the engine cylinder. In the present study, a standard preheating device is designed and fabricated in accordance with engine specifications and simulations were carried out under various operating conditions to evaluate its performance. Furthermore, experimental investigations were carried out in a compression ignition engine fueled with ethanol blends of 20 and 30% with diesel by volume and the fuel blends were preheated using burned exhaust gases. In addition, a comparative study has been carried out for preheated and non-preheated blends of E20 (20% of ethanol and 80% of diesel) and E30 with baseline diesel. The experimental results show that the preheated E20 (20% of ethanol and 80% of diesel) blend has higher brake thermal efficiency of 36.28% with a significant reduction in brake specific fuel consumption when compared with all the other blends. Moreover, the preheated E20 blend reduces the carbon monoxide, unburned hydrocarbon and smoke emissions by 49, 48 and 10%, respectively. However, the NOx emission is increased by 6% as compared to the non-preheating effect. It is also noted that the preheating of ethanol blends produced better combustion results with a significant reduction in the ignition delay period. Hence, it can be concluded that the ethanol fuel can be effectively used in a diesel engine by means of preheating using exhaust gases and could be a viable option for diesel engine applications.     

Effect of advanced injection timing on the performance of natural gas in diesel engines

Concern over the environment and/or the increasing demand for conventional fossil fuel has promoted interest in the development of alternative sources of fuel energy for internal combustion (IC) engines. The effect of advanced injection timing on the performance of natural gas used as primary fuel in dual-fuel combustion has been examined. Satisfactory diesel engine combustion demands self-ignition of the fuel as it is injected near the top dead centre (TDC) into the hot swirling compressed cylinder gas. Longer delays between injection and ignition lead to unacceptable rates of pressure rise (diesel knock) because too much fuel is ready to burn when combustion eventually occurs. Natural gas has been noted to exhibit longer ignition delays and slower burning rates especially at low load levels hence resulting in late combustion in the expansion stroke. Advanced injection timing is expected to compensate for these effects. The engine has standard injection timing of 30° before TDC (BTDC). The injection was first advanced by 5.5° given injection timing of 35.5° BTDC. The engine ran for about 5 minutes at this timing and stopped. The engine failed to start upon subsequent attempts. The injection was then advanced by 3.5° (i.e. 33.5° BTDC). The engine ran smoothly on this timing but seemed to incur penalty on fuel consumption especially at high load levels.     

Influence of alumina nanoparticles additives into biofuel (water hyacinth)-diesel mixture on diesel engine performance and emissions

The using diesel and biodiesel blends as a fuel has been a recent field of study especially with nanoparticles additives. The addition of alumina nanoparticles to biodiesel was verified to reduce emissions, while engine performance was not given great attention to evaluate the effect of blending alumina nanoparticles with the diesel and biodiesel mixture on the performance characteristics of the diesel engine. Then performance and emission tests were carried out by using different fuel samples in a single cylinder diesel engine. The brake thermal efficiency for the alumina nanoparticles (50 ppm, 100 ppm) and biodiesel blends were lower than that of biofuel (D80B20) blends, it was decreased by 2.5 %, 6.05 % respectively as compared to the blend (D80B20). The rate of carbon monoxide emissions for the two biodiesel and alumina blends were lower than that of the biodiesel blend (D80B20) and the best reduction was for the blend (D80B20N50) and was 76.3 % as compared with the biodiesel blend (D80B20). Also, the nitrogen oxides emissions for all the blends with nanoparticles were lower than that of the blend D80B20 due to shortened ignition delay and less fuel was added during the combustion which lead to reduction in nitrogen oxides emissions.     

Combustion performance of rubber seed methyl ester using aromatic and phenolic antioxidants in a multi-cylinder diesel engine

This paper analyzes the effect of antioxidants on engine combustion performance of a multi-cylinder diesel engine fueled with rubber seed biodiesel blends. Four antioxidants, namely 2-tert-butylbenzene-1,4-diol, N,N′-diphenyl-1,4-phenylenediamine, 2(3)-tert-Butyl-4-methoxyphenol and N-phenyl-1,4-phenylenediamine, were added at concentrations of 1000 and 2000 ppm to rubber seed biodiesel blends. Antioxidants blends increased the brake power by 4.21% and decreased the brake-specific fuel consumption by 6.82% compared to base biodiesel blends. The NO emissions reduction percentage for antioxidants fuels was 9.78% compared to base line biodiesel. However, the treated biodiesel blends increased carbon monoxide, hydrocarbon and smoke opacity up to 32.20, 42.15 and 43.92%, respectively, compared to non-treated blends. Compared to diesel fuel, antioxidants fuels decreased the brake power and increased the brake-specific fuel consumption, cylinder pressure and heat release rate. But compared to biodiesel blends, the cylinder pressure and heat release rate with antioxidants were reduced by 4.17 and 6.87%, respectively. It can be concluded that antioxidants addition is effective in increasing the oxidation stability and controlling the NO emissions of rubber seed biodiesel fueled diesel engines.     

Design of piston bowl geometry for better combustion in direct-injection compression ignition engine

The current computational fluid dynamics (CFD) study presents the effect of piston bowl geometry on the performance and emissions of a direct-injection diesel engine. Different piston bowl profiles, namely, hemispherical combustion chamber (HCC), shallow depth combustion chamber (SCC) and toroidal combustion chamber (TCC), have been created with a baseline compression ratio of 17.5. CONVERGE^TM CFD code coupled with the SAGE combustion model was used for numerical analysis. It is observed that the TCC piston bowl geometry renders better air–fuel mixture inside the cylinder, which leads to a homogeneous charge. Further, numerical experiments are carried out to analyze suitable TCC piston bowl geometry by varying the depth of the bowl. Out of all the cases, the case with 1.26 mm decrease in depth of bowl from the baseline (TCC) design gives better emissions and performance characteristics.     

A novel pilot-scale production of fuel gas by allothermal biomass gasification using biomass micron fuel (BMF) as external heat source

A novel pilot-scale allothermal biomass gasification system integrating steam gasification, thermal cracking, and catalytic reforming aiming at fuel gas production was developed. Biomass micron fuel (BMF) was used as external heat source by combusting with air in the combustor. Biomass feedstock was gasified with steam, and then, tar in the produced gas was decomposed by thermal cracking and catalytic reforming. The waste heat of high-temperature flue gas and fuel gas was recovered and used for biomass feedstock pre-heating and steam generation, respectively. The fuel gas yield is 1.36 Nm³/kg with lower heating value of 11.61 MJ/Nm³. An overall energy analysis of the system was also investigated. The results showed that the cold gas efficiency and energy conversion efficiency in this system are 88.11 and 63.59 %, respectively. Meanwhile, combustion of BMF accounts for 25.66 % of the total energy input.     

Effect of compression ratio on performance,emission and combustion characteristics of diesel–acetylene-fuelled single-cylinder stationary CI engine

The present investigation aims to depict the effect of compression ratio on performance, emission and combustion characteristics of diesel–acetylene-fuelled stationary compression ignition engine. The optimum values for compression ratio, injection timing and injection pressure for diesel were experimentally found, and baseline data were established as 20, 23° before top dead centre and 210 bar, respectively. In order to investigate the effect of acetylene fuelling, acetylene gas was inducted at four different flow rates of 60, 120, 180 and 240 litres per hour at compression ratio 20. It was observed that the flow rate of 120 litres per hour gave the best performance with highest brake thermal efficiency of 25.09%. In order to find the optimum compression ratio for acetylene fuelling at 120 litres per hour, experimentation was done at different compression ratios of 18, 19, 20, 21 and 22. Experimental results showed that highest brake thermal efficiency of 25.72% was achieved at compression ratio 21 for diesel–acetylene fuelling which was much higher than 23.32% for pure diesel. Carbon monoxide, hydrocarbon and smoke emissions were also measured and found to be lower, while the NOx emissions were higher at optimized values in dual-fuel mode as compared to those for pure diesel. Peak cylinder pressure and net heat release rate were also calculated and found to be higher in dual-fuel mode compared to diesel mode.     

Injection Strategy in Natural Gas–Diesel Dual-Fuel Premixed Charge Compression Ignition Combustion under Low Load Conditions

Dual-fuel premixed charge compression ignition (DF-PCCI) combustion has been proven to be a viable alternative to conventional diesel combustion in heavy-duty compression ignition engines due to its low nitrogen oxides (NO_x) and particulate matter (PM) emissions. When natural gas (NG) is applied to a DF-PCCI engine, its low reactivity reduces the maximum pressure rise rate under high loads. However, the NG–diesel DF-PCCI engine suffers from low combustion efficiency under low loads. In this study, an injection strategy of fuel supply (NG and diesel) in a DF-PCCI engine was investigated in order to reduce both the fuel consumption and hydrocarbon (HC) and carbon monoxide (CO) emissions under low load conditions. A variation in the NG substitution and diesel start of energizing (SOE) was found to effectively control the formation of the fuel–air mixture. A double injection strategy of diesel was implemented to adjust the local reactivity of the mixture. Retardation of the diesel pilot SOE and a low fraction of the diesel pilot injection quantity were favorable for reducing the combustion loss. The introduction of exhaust gas recirculation (EGR) improved the fuel economy and reduced the NO_x and PM emissions below Euro VI regulations by retarding the combustion phasing. The combination of an NG substitution of 40%, the double injection strategy of diesel, and a moderate EGR rate effectively improved the combustion efficiency and indicated efficiency, and reduced the HC and CO emissions under low load conditions.     

E150柴油机缸内压缩温度场的全息干涉测量

介绍了采用激光双曝光全息干涉技术测取柴油机压缩温芳场的基本原理及实验过程。提出了利用绝热压缩缩区的温度作为计算干涉条纹的初始条件,从而为计算全息干涉条纹所对应温度提供了可行的方法。由柴油机压缩过程中缸内的温度场的测量结果可以看出,在柴油机压缩过程中,缸内温度变化幅度在４０Ｋ左右,最大温度梯度是在靠近燃烧室壁面大约０．５ｍｍ的区域内。本文的实验结果,为分析柴油机压缩过程缸内传热过程提供了依据;所使用     

The operation of a turbulence chamber diesel engine with LPG fumigation for exhaust emissions control

An experimental study is conducted to evaluate the use of liquefied petroleum gas (LPG) as a secondary fuel for a Ricardo E-6, naturally aspirated, four-stroke diesel engine having a turbulence combustion chamber (indirect injection). The gaseous LPG is introduced together with the aspirated air (fumigation) at various proportions with respect to the diesel fuel which constitutes the main part. The influence of fuel feed ratios (LPG/diesel), in a vast range of loads, on fuel consumption, pressure diagrams, exhaust smokiness and exhaust gas emissions (nitrogen oxides, hydrocarbons and carbon monoxide) is investigated, the baseline being the single diesel fuel operation. The study for this type of engine, which has not being reported in the literature, shows a promise of the present method and reveals that above 60 per cent of maximum load the whole effect is beneficial concerning specific fuel consumption and smoke reduction. The examination of gaseous pollutant levels shows an involved relation with respect to load and fuel proportions. The best results (coupled to acceptable cylinder pressure levels) is obtained at a diesel fuel substitution value of 75% of maximum load, with an LPG mass fraction in the range 10 to 15%.     

A numerical study on the performance,combustion and emission parameters of a compression ignition engine fuelled with diesel,palm stearin biodiesel and alcohol blends

A numerical simulation has been carried out in this study to evaluate the effect of alcohol addition to the blends of diesel and palm stearin biodiesel on the performance, combustion and emission of a diesel engine. The commercial software Diesel-RK has been used in this study to simulate a single-cylinder, naturally aspirated, direct injection, four-stroke diesel engine. The simulated results have been validated against experimental observation for the base fuel diesel. The effects of two alcohols, namely ethanol and methanol have been separately investigated and compared. The results indicate that although the brake-specific fuel consumption is slightly increased, the other performance characteristics and the entire combustion and emission parameters are improved with alcohol addition to diesel–biodiesel blends. The instantaneous heat release rate, ignition delay and oxides of nitrogen emission are found to be more with methanol than with ethanol. The diesel–biodiesel blend also shows better combustion and emission characteristics than that of diesel except oxides of nitrogen emission.     

An experimental investigation on the performance,combustion and emission characteristics of a variable compression ratio diesel engine using diesel and palm stearin methyl ester

An attempt has been made to use biodiesel prepared from non-edible portion of palm oil as fuel of a conventional mono-cylinder compression ignition engine. The present experimental investigation takes into account the combined effect of using blends of diesel–palm stearin biodiesel as fuels and the compression ratio on different performance, combustion and emission characteristics of the said engine. The experiments have been carried out on a single-cylinder, direct injection diesel engine at varying compression ratio of 16:1–18:1 in four steps. It is observed that the brake thermal efficiency reduces by 7.9% when neat biodiesel is used instead of diesel. But, it increases with the increase in compression ratio for all the blends. Brake specific fuel consumption and exhaust gas temperature increase with the addition of biodiesel to diesel and also with the increase in compression ratio. Heat release rate decreases with biodiesel, and it is minimum at the rated compression ratio of 17.5:1 for all the fuels considered here. On the other hand, ignition delay is found to be more with neat diesel, and it increases with the decrease in compression ratio. Significant reductions in emissions of carbon monoxide (CO), hydrocarbon (HC) and smoke are observed with biodiesel, while the emissions of oxides of nitrogen (NO_x) and carbon dioxide (CO₂) increase. The decrease in compression ratio increases the emissions of CO, HC and smoke, but the emissions of NO_x and CO₂ decrease with the decrease in compression ratio.     

Experimental investigation on performance and emission characteristics of a compression ignition engine fueled with biodiesel from waste tallow

Tallow oil being one of the non-edible oils can be explored for biodiesel production; however, limited information is available in literature regarding the use of tallow biodiesel as an alternate form of energy. This study deals with systematic characterization of tallow biodiesel to find its suitability for diesel engines. The chemical nature and composition of tallow biodiesel as determined by NMR, FTIR and GC analyses are closely related to established biodiesel properties. In this investigation, tallow biodiesel blends (B10, B20 and B100) were used to study the performance and emission of compression ignition engine at different loads (20, 40, 60, 80 and 100%), and the results were then compared with baseline results of conventional base diesel. The fuel properties of biodiesel and its blends were also determined which were comparable with that of diesel. Brake thermal efficiency for biodiesel blends were in comparable range with that of base diesel. The average reduction in carbon monoxide, hydrocarbon and smoke emission for B100 blend of biodiesel was observed to be 16.04, 28.09 and 28.57%, respectively, compared to base diesel. However, there was an average increase in NOx emission (15.34%) for B100 blend compared to diesel. The overall results show that tallow biodiesel could be recommended as a diesel fuel alternate.     

CO2 mitigation potential from biodiesel of castor seed oil in Indian context

Biodiesel has become an interesting alternative to be used in diesel engine, because it has similar properties to the traditional fossil diesel fuel and may, thus, substitute conventional fuel with none or very minor engine modification. This article deals with alkaline transesterfication of castor oil and their properties for engine application. The purpose of the transesterfication process is to lower the viscosity of the oil from 226.82 cS to 8.50 cS ‘at’ 38°C. The flash point values of castor methyl esters are lower than that of castor oil. The density and gross calorific value of castor methyl ester are much closer to those of diesel. If 10% of total production of castor seed oil is transesterfied into biodiesel, then about 79,782 tones of CO₂ emission can be saved on annual basis. The CO₂ released during combustion of biodiesel can be recycled through next crop production, therefore, no additional burden on environment.     

根据瞬时转速与冲击信号诊断柴油机故障的方法

建立多缸柴油机传动机构三维实体模型,理论上模拟柴油机正常以及异常发火情况下的瞬时转速波形图,分析其故障特征。以WP10.340E32型柴油机为研究对象,搭建柴油机故障模拟实验台以及柴油机运行在线监测系统,模拟、捕捉柴油机单缸不点火故障。从得到瞬时转速、特定相位缸体振动信号入手,对比正常情况下信号特征,分析失火故障与特征信号的内在联系。通过仿真和实测数据证明瞬时转速结合振动冲击相位信号可有效识别柴油机失火故障并且能准确定位故障缸所在位置,从而实现诊断过程的简化。     

Numerical prediction of the performance,combustion and emission characteristics of a CI engine using different biodiesels

An attempt has been made to investigate numerically the energetic, combustion and environmental performances of a single-cylinder naturally aspirated direct injection diesel engine using the commercial software, Diesel-RK. Diesel and five different biodiesels, namely jatropha biodiesel, soybean biodiesel, palm stearin biodiesel, karanja biodiesel and rapeseed biodiesel, are used separately as fuels in this study. Experiments have also been conducted with diesel and palm stearin biodiesel to validate the predicted results. The experimental and the numerical results match both qualitatively and quantitatively with slight deviations. The analysis of the numerical results shows that the engine performance deteriorates with the use of different biodiesels as fuels. Brake thermal efficiency decreases by 3% (maximum) in case of palm stearin biodiesel. On the other hand, brake specific fuel consumption and brake specific energy consumption increase and the maximum values are found to be 25.8 and 3.6%, respectively. Among the biodiesels, jatropha biodiesel showed the best performance and palm stearin biodiesel showed the worst. When the combustion characteristics were compared, it was noted that both the ignition delay period and the heat release rate decrease to some extent for different biodiesels compared to diesel. The use of biodiesel gives a cleaner exhaust compared to that of diesel, and jatropha biodiesel gives the cleanest exhaust in terms of particulate matter and smoke emissions. However, the formation of nitrogen oxides increases with the use of biodiesels and the maximum increase was noted with rapeseed biodiesel.     

Emission reduction on ethanol–gasoline blend using cerium oxide nanoparticles as fuel additive

In this study, the effect of ethanol–gasoline blend with cerium oxide nanoparticles as additive on a Tata Nano twin–cylinder SI engine was investigated. In this work, the combustion, performance and emission tests were conducted. The experiment fuels were prepared using 99.9% pure ethanol and gasoline with cerium oxide nanoparticles. The volumetric percentages of ethanol–gasoline blends with cerium oxide nanoparticles additive are in the ratio of E30, E40 and E50. These represent the ratios of ethanol amount in the total blend and the rest of gasoline. Additionally, 100?mg, 150?mg and 200?mg cerium oxide nanoparticles additive are mixed to E30, E40 and E50, respectively. The venture of this investigation was to reformulate the fuel to utilize the cerium oxide nanoparticles with ethanol and gasoline blend to develop the fuel’s performance and to decrease the pollution from the engine. The experimental results expose an increase in brake thermal efficiency for the nanoparticles blends. In the emission test CO, CO₂, HC and NOx are noticeably reduced, and O₂ increased for all the blends. In combustion analyses, the cylinder pressure is higher for nanoparticles blends, when compared to that of the sole fuel.     

New alternative (partially homogeneous) combustion process as a method for reduction of concentrations of nitric oxides and soot in combustion products of diesel

A new alternative (partially homogeneous) combustion process in diesel engines is proposed that provides changes in local values of the excess air coefficient and the temperature of the working substance in ranges lying beyond the area of the formation of nitric oxides and soot. It is important that the process is realized without significant changes in the serial construction. Modeling of the alternative process and the traditional diesel engine process is carried out on the basis of fundamental equations of three-dimensional nonstationary transfer in combination with models of combustion and formation of harmful substances: nitric oxides and soot. The set of equations for the model of the diesel cylinder with moving boundaries (valves, piston) is used in the Reynolds form and is closed by means of the k-ξ-f turbulence model considering the near-wall anisotropy of turbulence. The developed 3D models of the diesel engine work process are realized in the CFD code of the AVL-FIRE software complex. It is found that transition from the classic diesel engine process to partially homogeneous combustion makes it possible to block practically completely the formation of nitric oxides and to decrease soot emission substantially.     

柴油机工作不均匀性的振动检测方法

在某型号装备的柴油机上，采用断缸的方法模拟各缸工作不均匀试验，测量柴油机在不同工作状态下一个工作循环内的机体振动信号。利用局域波分解方法对柴油机振动信号进行时频分析，获得Hilbert时频谱。对柴油机在不同工作状态下振动信号的时频谱进行分析，对各缸段的振动信号频率变化进行统计分析，计算频率偏差，并分析其在不同工作状态下的变化趋势。分析结果表明，利用各缸段振动信号频率变化的偏差可以对柴油机工作不均匀性进行判别。