Effect of hydroxy and hydrogen gas addition on diesel engine fuelled with microalgae biodiesel

Owing to high growth rate, being non-edible, and environmental friendliness; microalgae is a promising third generation biodiesel raw material. In this study, hydrogen and hydroxy gas aspirated compression ignition engine which was fuelled with microalgae biodiesel and low sulphur diesel fuel blend were investigated in order to evaluate their combined effect. The results showed that the brake power and torque output of the test engine decreased with microalgae biodiesel usage. Moreover, microalgae biodiesel addition results in lower carbon monoxide and nitrogen oxides emissions, and higher carbon dioxide. The introduction of hydrogen and hydroxy gas compensated the decrement of torque and power output and increment of carbon dioxide emission. The study enlightened that usage of microalgae biodiesel with hydrogen and hydroxy gas addition is a very promising combination from the environmental viewpoint.     

Influence of hydrogen co-combustion with diesel fuel on performance,smoke and combustion phases in the compression ignition engine

The main objective of this study was to examine impact of hydrogen addition to the compression ignition engine fueled with either rapeseed methyl ester (RME) or 7% RME blended diesel fuel (RME7) on combustion phases and ignition delay as well as smoke and exhaust toxic emissions. Literature review shows in general, hydrogen in those cases is used in small amounts below lower flammability limits. Novelty of this work is in applying hydrogen at amounts up to 44% by energy as secondary fuel to the compression ignition engine. Results from experiments show that increase of hydrogen into the engine makes ignition delay shortened that also affects main combustion phase. In all tests the trends of exhaust HC and CO toxic emissions vs. hydrogen addition were negative. The trend of smokiness decreased steadily with increase of hydrogen. Amounts of hydrogen addition by energy share were limited to nearly 35% due to combustion knock occurring at nominal load.     

Direct injection of hydrogen main fuel and diesel pilot fuel in a retrofitted single-cylinder compression ignition engine

Up to 90% hydrogen energy fraction was achieved in a hydrogen diesel dual-fuel direct injection (H2DDI) light-duty single-cylinder compression ignition engine. An automotive-size inline single-cylinder diesel engine was modified to install an additional hydrogen direct injector. The engine was operated at a constant speed of 2000 revolutions per minute and fixed combustion phasing of ?10 crank angle degrees before top dead centre (°CA bTDC) while evaluating the power output, efficiency, combustion and engine-out emissions. A parametric study was conducted at an intermediate load with 20–90% hydrogen energy fraction and 180-0 °CA bTDC injection timing. High indicated mean effective pressure (IMEP) of up to 943 kPa and 57.2% indicated efficiency was achieved at 90% hydrogen energy fraction, at the expense of NO_x emissions. The hydrogen injection timing directly controls the mixture condition and combustion mode. Early hydrogen injection timings exhibited premixed combustion behaviour while late injection timings produced mixing-controlled combustion, with an intermediate point reached at 40 °CA bTDC hydrogen injection timing. At 90% hydrogen energy fraction, the earlier injection timing leads to higher IMEP/efficiency but the NO_x increase is inevitable due to enhanced premixed combustion. To keep the NO_x increase minimal and achieve the same combustion phasing of a diesel baseline, the 40 °CA bTDC hydrogen injection timing shows the best performance at which 85.9% CO₂ reduction and 13.3% IMEP/efficiency increase are achieved.     

Hydrogen supplemented natural gas effect on a DI diesel engine operating under dual fuel mode with a biodiesel pilot fuel

In order to slow down the continuing environmental deterioration, regulations for pollutant emissions limitations are increasingly rigorous. The development of new alternative fuels for internal combustion engines is a very interesting solution not only to overcome the pollution problem but also because of the petroleum shortage. In this context, the present work investigates the improvement of a DI diesel engine operating at constant speed (1500 rpm) and under dual fuel mode with eucalyptus biodiesel and natural gas (NG) enriched by various H₂ quantities (15, 25 and 30 by v%). The eucalyptus biodiesel quantity injected into the engine cylinder is kept constant, to supply around 10% of the engine nominal power, for all examined engine loads. The engine load is further increased using only the gaseous fuel (NG+H₂), which is introduced with the intake air. The effect of H₂/NG blending ratio on the combustion parameters, performance and pollutant emissions of the engine is investigated and compared with those of pure NG case. An important benefit in terms of brake specific fuel consumption, reaching a decrease of 4–10% with the 25% H₂ blend compared to the pure NG case, is achieved. Concerning the pollutant emissions, NG enrichment with H₂ is an efficient solution to enhance the combustion process and hence reduce carbon monoxide, unburned hydrocarbon and soot emissions at high loads where they are important for pure NG. However for the nitrogen oxide emissions, NG blending with H₂ is attractive only at low and medium loads where their levels are lower than pure NG.     

A review of ammonia as a compression ignition engine fuel

During the past decades, the diesel engine has been through times of upheaval, boom and bust. At the beginning of the century, almost 50% of the new vehicle registrations in the European market were diesel-powered. However, the news of deadly diesel NO_x emissions supported by the diesel emission scandals caused a shock to the diesel engine market, and the sustainability of the diesel engine is currently in dispute.Recently major automotive manufacturers announced the development of diesel-powered vehicles with negligible NO_x emissions. Moreover, the NO_x emissions production is of lower concern for heavy-duty, marine or power generations applications where the implementation of advanced aftertreatment systems is feasible. However, despite the tackle of NO_x emissions, the decarbonisation of the automotive, marine and power generation markets is mandatory for meeting greenhouse gas emissions targets and limiting global warming.The decarbonisation of the diesel engine can be achieved by the implementation of a carbon-free fuel such as ammonia. This paper provides a detailed overview of ammonia as a fuel for compression ignition engines. Ammonia can be combusted with diesel or any other lower autoignition temperature fuel in dual-fuel mode and lead to a significant reduction of carbon-based emissions. The development of advanced injection strategies can contribute to enhanced performance and overall emissions improvement. However, ammonia dual-fuel combustion currently suffers from relatively high unburned ammonia and NO_x emissions because of the fuel-bound nitrogen. Therefore, the implementation of aftertreatment systems is required. Hence, ammonia as a compression ignition fuel can be currently seen as a feasible solution only for marine, power generation and possibly heavy-duty applications where no significant space constraints exist.     

An experimental study of a direct injection compression ignition hydrogen engine

This paper describes the development of an experimental setup for the testing of a diesel engine in the direct injection hydrogen-fuelled mode. Test results showed that the use of hydrogen direct injection in a diesel engine gave a higher power to weight ratio when compared to conventional diesel-fuelled operation, with the peak power being approximately 14% higher. The use of inlet air heating was required for the hydrogen-fuelled engine to ensure satisfactory combustion, and a large increase in the peak in-cylinder gas pressure was observed. A significant efficiency advantage was found when using hydrogen as opposed to diesel fuel, with the hydrogen-fuelled engine achieving a fuel efficiency of approximately 43% compared to 28% in the conventional, diesel-fuelled mode. A reduction in nitrogen oxides emission formation of approximately 20% was further observed.     

Effect of hydrogen enrichment in the intake air of diesel engine fuelled with honge biodiesel blend and diesel

In the current investigation, the enrichment of hydrogen with the honge biodiesel blend and diesel is used in a compression ignition engine. The biodiesel is derived from the honge oil and mixed with diesel fuel by 20% (v/v). Thereafter, hydrogen at different volume flow rates (10 and 13 lpm) is introduced into the intake manifold. The outcomes by enrichment of hydrogen on the performance, combustion and emission characteristics are investigated by examining the brake thermal efficiency, fuel consumption, HC, CO, CO₂, NOₓ emissions, in-cylinder pressure, combustion duration, and rate of heat release. The engine fuelled with honge biodiesel blend is found to enhance the thermal efficiency, combustion characteristics. Compare to diesel, the BTE increased by 2.2% and 6% less fuel consumption for the HB20 + 13H₂ blend. Further, reduction in the emission of exhausts gases like CO and HC by 21% and 24%, respectively, are obtained. This is due to carbon-free structure in hydrogen. Moreover, due to high pressure in the cylinder, there is a slight increase in oxides of nitrogen emission compare to diesel. The combustion characteristics such as rate of heat release, combustion duration, and maximum ₂rate of pressure rise and in-cylinder pressure are high due to hydrogen.     

Effect of fuel opening injection pressure and injection timing of hydrogen enriched rice bran biodiesel fuelled in CI engine

Fuel opening injection pressure and injection timing are important injection parameters, and they have a significant influence on engine combustion, performance, and emissions. The focus of this work is to improve the performance and emissions of single-cylinder diesel engines by using injection parameters in engines running with rice bran biodiesel 10% blend (RB10+H₂) and 20% blend (RB20+H₂) with a fixed hydrogen flow rate of 7 lpm. In addition, hydrogen and biodiesel are excellent alternatives to conventional fuels, which can reduce energy consumption and strict emission standards. The investigation is conducted for three different opening injection pressure of 220, 240, 260 bar, and four different injection timings of 20°, 22°, 24°, and 26° bTDC. Results indicate that the sample ‘RB10+H₂’ provides 3.32% higher BTE and reduces the fuel consumption by 13% as diesel fuel. The blend RB10+H₂ attributes a maximum cylinder pressure of 68.7 bar and a peak HRR value of 49 J/ºCA. Further, compared to diesel, RB10+H₂ blend emits lower CO, HC, and smoke opacity by 17%, 22%, and 16%, respectively. However, an almost 12% increase of nitrogen oxides for the RB10+H₂ blend is observed. However, with advanced injection timing and higher opening injection pressure, NOx emissions is slightly increased.     

The utilization of hydrogen in hydrogen/diesel dual fuel engine

A hydrogen fueled internal combustion engine has great advantages on exhaust emissions including carbon dioxide (CO₂) emission in comparison with a conventional engine fueling fossil fuel. In addition, if it is compared with a hydrogen fuel cell, the hydrogen engine has some advantages on price, power density, and required purity of hydrogen. Therefore, they expect that hydrogen will be utilized for several applications, especially for a combined heat and power (CHP) system which currently uses diesel or natural gas as a fuel.A final goal of this study is to develop combustion technologies of hydrogen in an internal combustion engine with high efficiency and clean emission. This study especially focuses on a diesel dual fuel (DDF) combustion technology. The DDF combustion technology uses two different fuels. One of them is diesel fuel, and the other one is hydrogen in this study. Because the DDF engine is not customized for hydrogen which has significant flammability, it is concerned that serious problems occur in the hydrogen DDF engine such as abnormal combustion, worse emission and thermal efficiency.In this study, a single cylinder diesel engine is used with gas injectors at an intake port to evaluate performance swung the hydrogen DDF engine with changing conditions of amount of hydrogen injected, engine speed, and engine loads. The engine experiments show that the hydrogen DDF operation could achieve higher thermal efficiency than a conventional diesel operation at relatively high engine load conditions. However, it is also shown that pre-ignition with relatively high input energy fraction of hydrogen occurred before diesel fuel injection and its ignition. Therefore, such abnormal combustion limited amount of hydrogen injected. Fire-deck temperature was measured to investigate causal relationship between fire-deck temperature and occurrence of pre-ignition with changing operative conditions of the hydrogen DDF engine.     

Effect of hydrogen and LPG addition on the efficiency and emissions of a dual fuel diesel engine

This paper presents some experimental investigations on dual fuel operation of a 4 cylinder (turbocharged and intercooled) 62.5 kW gen-set diesel engine with hydrogen, liquefied petroleum gas (LPG) and mixture of LPG and hydrogen as secondary fuels. Results on brake thermal efficiency and emissions, namely, un-burnt hydrocarbon (HC), carbon monoxide (CO), NO_x and smoke are presented here. The paper also includes vital information regarding performances of the engine at a wide range of load conditions with different gaseous fuel substitutions. When only hydrogen is used as secondary fuel, maximum enhancement in the brake thermal efficiency is 17% which is obtained with 30% of secondary fuel. When only LPG is used as secondary fuel, maximum enhancement in the brake thermal efficiency (of 6%) is obtained with 40% of secondary fuel. Compared to the pure diesel operation, proportion of un-burnt HC and CO increases, while, emission of NO_x and smoke reduces in both cases. On the other hand, when 40% of mixture of LPG and hydrogen is used (in the ratio 70:30) as secondary fuel, brake thermal efficiency enhances by 27% and HC emission reduces by 68%. Further, shortcoming of low efficiency at lower load condition in a dual fuel operation is removed when a mixture of hydrogen and LPG is used as the secondary fuel at higher than 10% load condition.     

Genetic programming approach to predict torque and brake specific fuel consumption of a gasoline engine

This study presents genetic programming (GP) based model to predict the torque and brake specific fuel consumption a gasoline engine in terms of spark advance, throttle position and engine speed. The objective of this study is to develop an alternative robust formulations based on experimental data and to verify the use of GP for generating the formulations for gasoline engine torque and brake specific fuel consumption. Experimental studies were completed to obtain training and testing data. Of all 81 data sets, the training and testing sets consisted of randomly selected 63 and 18 sets, respectively. Considerable good performance was achieved in predicting gasoline engine torque and brake specific fuel consumption by using GP. The performance of accuracies of proposed GP models are quite satisfactory (R² = 0.9878 for gasoline engine torque and R² = 0.9744 for gasoline engine brake specific fuel consumption). The prediction of proposed GP models were compared to those of the neural network modeling, and strictly good agreement was observed between the two predictions. The proposed GP formulation is quite accurate, fast and practical.     

Prediction of torque and specific fuel consumption of a gasoline engine by using artificial neural networks

This study presents an artificial neural network (ANN) model to predict the torque and brake specific fuel consumption of a gasoline engine. An explicit ANN based formulation is developed to predict torque and brake specific fuel consumption of a gasoline engine in terms of spark advance, throttle position and engine speed. The proposed ANN model is based on experimental results. Experimental studies were completed to obtain training and testing data. Of all 81 data sets, the training and testing sets consisted of randomly selected 63 and 18 sets, respectively. An ANN model based on a back-propagation learning algorithm for the engine was developed. The performance and an accuracy of the proposed ANN model are found satisfactory. This study demonstrates that ANN is very efficient for predicting the engine torque and brake specific fuel consumption. Moreover, the proposed ANN model is presented in explicit form as a mathematical function.     

Performance and combustion characteristic of CI engine fueled with hydrogen enriched diesel

The combustion of hydrogen–diesel blend fuel was investigated under simulated direct injection (DI) diesel engine conditions. The investigation presented in this paper concerns numerical analysis of neat diesel combustion mode and hydrogen enriched diesel combustion in a compression ignition (CI) engine. The parameters varied in this simulation included: H₂/diesel blend fuel ratio, engine speed, and air/fuel ratio. The study on the simultaneous combustion of hydrogen and diesel fuel was conducted with various hydrogen doses in the range from 0.05% to 50% (by volume) for different engine speed from 1000 – 4000 rpm and air/fuel ratios (A/F) varies from 10 – 80. The results show that, applying hydrogen as an extra fuel, which can be added to diesel fuel in the (CI) engine results in improved engine performance and reduce emissions compared to the case of neat diesel operation because this measure approaches the combustion process to constant volume. Moreover, small amounts of hydrogen when added to a diesel engine shorten the diesel ignition lag and, in this way, decrease the rate of pressure rise which provides better conditions for soft run of the engine. Comparative results are given for various hydrogen/diesel ratio, engine speeds and loads for conventional Diesel and dual fuel operation, revealing the effect of dual fuel combustion on engine performance and exhaust emissions.     

Comparative performance analysis of diesel engine fuelled with hydrogen enriched edible and non-edible biodiesel

In the present study, a comparative analysis of enrichment of hydrogen alongside diesel fuel and two different sources of biodiesel namely rice bran oil is an edible oil, and karanja oil being non-edible is tested. Hydrogen at a fixed flow rate of 7 lpm is inducted through the intake manifold. A total of six fuel samples are considered: diesel (D), hydrogen-enriched diesel (D + H₂), hydrogen-enriched 10, and 20% rice bran biodiesel blend (RB10 + H₂ and RB20 + H₂), and hydrogen-enriched 10 and 20% karanja biodiesel blend (KB10 + H₂ and KB20 + H₂). Results indicate that enrichment of hydrogen improves combustion and results in 2.5% and 1.6% increase in the brake thermal efficiency of diesel fuel and rice bran biodiesel, respectively. For karanja biodiesel the increment is negligible. Fuel consumption of the D + H? is 6.35% lower and for RB10 + H? and KB10 + H? it is decreased by 2.9% and 1.3%, respectively. The Presence of hydrogen shows the 4–38% lower CO emissions and 6–14% lower UHC emission due to better combustion. The blends RB10 + H? and KB10 + H? produce up to 6–13% higher NOx emission and that for the blends RB20 + H? and KB20 + H? it goes up to 25%. Overall rice bran oil is found to provide better performance than karanja biodiesel.     

Effects of hydrogen addition on engine performance in a spark ignition engine with a high compression ratio under lean burn conditions

In this study, the effects of hydrogen addition on the engine performance were investigated using spark ignition engine fueled gasoline with a compression ratio of 15 at an air excess ratio (λ) of 1.8 and above. At λ = 1.8, the indicated thermal efficiency at the spark timing of the knock limit reached the maximum level under the conditions in which the hydrogen fraction was set to 4% of the heating value of the total fuel. Based on a heat balance analysis, the best hydrogen fraction was found as a balance between the improvement in the burning efficiency and the increase in heat loss. The lean limit was extended when the hydrogen fraction was increased from λ = 1.80 to λ = 2.28. The hydrogen addition achieved the maximum indicated thermal efficiency at spark timing of the knock limit was obtained at λ = 2.04, where the hydrogen fraction was 10%.     

Optimization of exhaust emissions,vibration, and noise of a hydrogen enriched fuelled diesel engine

In this study, the effects of various input parameters are examined on exhaust emissions, vibration, and noise of an unmodified diesel engine. The primary aim of this study is to optimize the vibration, noise, and exhaust emissions of the engine to get optimal configuration parameters. Experiments were carried out on a four-stroke, four-cylinder, diesel engine fuelled with diesel-biodiesel-hydrogen blends. To minimize the number of experiments Box-Behnken design (BBD) has been adopted. Optimum desirability is found as 0.862 with hydrogen addition of 4.63 L/min, fuel blend of 26.8% and 1500 rpm engine speed for the diesel engine. When the diesel engine is operated at 1500 rpm engine speed and fuelled with 4.63 L/min hydrogen addition and 26.8% biodiesel blend ratio; the optimum responses of CO, CO₂, NO_x, vibration, and noise are established as 214 ppm, 1.35%, 90.4 ppm, 38.6 m/s², and 91.3 dB[A], respectively. The predicted values were confirmed experimentally and the errors in predicted values are found in a limit range.     

A comprehensive study on performance,emission and combustion behavior of a compression ignition engine fuelled with WCO (waste cooking oil) emulsion as fuel

This work aims at evaluating the performance, emission and combustion of a diesel engine fuelled with WCO (waste cooking oil obtained from palm oil) and its emulsion as fuel. A single cylinder water-cooled diesel engine was used. Base data was generated with diesel and neat WCO as fuels. Subsequently, WCO oil was converted into its emulsion and tested. Neat WCO resulted in higher smoke, hydrocarbon and carbon monoxide emissions as compared to neat diesel. Significant reduction in all emission was achieved with the WCO emulsion. Cylinder peak pressure and maximum rate of pressure rise were found to be higher with WCO emulsion as compared to neat WCO mainly at high power outputs. Ignition delay was found as higher with neat WCO and its emulsion. It is concluded that WCO emulsion can be used in diesel engines without any modifications in the engine with superior performance and reduced emissions at high power outputs.     

Experimental investigation on effect of misfire and postfire on backfire in a hydrogen fuelled automotive spark ignition engine

This study investigates the effect of misfire and postfire on backfire in a hydrogen-fuelled automotive spark ignition engine. Backfire is a preignition phenomenon and the flame propagates toward the engine's intake manifold during the suction stroke. Postfire is a post-ignition phenomenon occurring in the exhaust manifold during the exhaust stroke and the flame propagates towards the exhaust manifold or backflow to the combustion chamber or combined both. Misfire occurs when cranking the engine (starting), fouled spark plug, and unoptimized spark timing. Several misfire cycles lead to an increase in the accumulation of unburnt hydrogen-air charge inside the cylinder and 13% hydrogen leaves the exhaust manifold resulting in postfire occurrence in a subsequent cycle. The postfire in the current cycle acting as an external ignition source for the preignition of the accumulated hydrogen-air charge results in backfire in the immediate next cycle. The misfire, postfire and backfire stall the engine operation due to a drop in indicated mean effective pressure. The experimental data indicates the backfire limiting equivalence ratio (BLER) should decrease with an increase in the engine speed as the equivalence ratio varies from 0.91 at 2000 rpm to 0.4 at 4900 rpm. As too advancement of spark timing increases the probability of misfire leading to postfire and backfire, the engine must be operated at backfire limiting spark timing to avoid misfire, postfire, and backfire occurrence. An important point emerged from this study that misfire without postfire does not lead to backfire occurrence. Physical mechanisms and mitigative measures for misfire, postfire and backfire are discussed in detail.     

Effect of natural antioxidant additive on hydrogen-enriched biodiesel operated compression ignition engine

The environmental degradation and depletion of fossil fuel, urges the need of renewable fuel for IC engines. Among the renewable fuel, biodiesel are widely used as alternative fuel but for recent years hydrogen is also considered as alternative fuel because of zero emission but it possess higher auto ignition temperature. In order to reduce the self-ignition temperature of hydrogen and another liquid fuel is mixed and operated as a dual fuel mode condition in CI engine. The current investigation aims to analyse the impact of natural antioxidant additive on hydrogen-enriched biodiesel operation in a diesel engine. During the experimentation process hydrogen is admitted at the intake manifold and B20 blend of juliflora biodiesel is injected in combustion cylinder. The three test fuel samples are used for the experimentation process such as diesel, B20 and B20 with hydrogen in different flow rates such as 8, 10, 12, 16,20lpm. B20 with hydrogen shows an increment of brake thermal efficiency (BTE). Among the test fuels B20 + 16lpm and B20 + 20lpm blends have better improvement of BTE of 28.815% and 28.32%, which is higher than the conventional engine at maximum load CO, HC emission is also lower for B20 + 16lpm and B20 + 20lpm than other blends but the NO_x emission increases of 26 and 28% than diesel respectively. In order to minimize the NO_x emission, natural antioxidant additive Melia Azedarach (MA) of 1000 ppm is added to B20 + 16lpm and found that B20 + 16lpm with MA shows an improvement of BTE 2.17% higher than B20 + 16lpm without additive and the NO_x emission for B20 + 16lpm with additive is 1079 ppm, which is 21.9% lower than B20 + 16lpm without additives. Therefore B20 + 16lpm with additive is superior than other test blends.     

Investigations on the combustion parameters of a dual fuel diesel engine with hydrogen and LPG as secondary fuels

This paper presents a detailed experimental investigations on the combustion parameters of a 4 cylinder (turbocharged and intercooled) 62.5 kW gen-set duel fuel diesel engine (with hydrogen and LPG as secondary fuels). A detailed account on maximum rate of pressure rise, peak cylinder pressure, heat release rate in first phase of combustion and combustion duration at a wide range of load conditions with different gaseous fuel substitutions has been presented in the paper. When 30% of hydrogen alone is used as secondary fuel, maximum rate of pressure rise increases by 0.82 bar/deg CA as compared to pure diesel operation, while, peak cylinder pressure and combustion duration increase by 8.44 bar and 5 deg CA respectively. When 30% of LPG alone is used as secondary fuel, the enhancements in maximum rate of pressure rise, peak cylinder pressure and combustion duration are found to be 1.37 bar/deg CA, 6.95 bar and 5 deg CA respectively. It is also found that heat release rate in first phase of combustion reduces at all load conditions as compared to the pure diesel operation in both types of fuel substitutions.One important finding of the present work is significant enhancement in performances of dual fuel engine when hydrogen-LPG mixture is used as the secondary fuel. The highlight of this case is that when the mixture of LPG and hydrogen (40% in the ratio LPG: hydrogen = 70:30) is used as secondary fuel, maximum rate of pressure rise (by 0.88 bar/deg CA) and combustion duration reduces (by 4 deg CA), while, peak cylinder pressure and heat release rate in first phase of combustion increase by 5.25 bar and 35.24 J/deg CA respectively.