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An insight on hydrogen fuel injection techniques with SCR system for NOX reduction in a hydrogen–diesel dual fuel engine
Abstract
Internal combustion engines continue to dominate in many fields like transportation, agriculture and power generation. Among the various alternative fuels, hydrogen is a long-term renewable and less polluting fuel (Produced from renewable energy sources). In the present experimental investigation, the performance and emission characteristics were studied on a direct injection diesel engine in dual fuel mode with hydrogen inducted along with air adopting carburetion, timed port and manifold injection techniques. Results showed that in timed port injection, the specific energy consumption reduces by 15% and smoke level by 18%. The brake thermal efficiency and NOX increases by 17% and 34% respectively compared to baseline diesel. The variation in performance between port and manifold injection is not significant. The unburnt hydrocarbons and carbon monoxide emissions are lesser in port injection. The oxides of nitrogen are higher in hydrogen operation (both port and manifold injection) compared to diesel engine. In order to reduce the NOX emissions, a selective catalytic converter was used in hydrogen port fuel injection. The NOX emission reduced upto a maximum of 74% for ANR (ratio of flow rate of ammonia to the flow rate of NO) of 1.1 with a marginal reduction in efficiency. Selective catalytic reduction technique has been found to be effective in reducing the NOX emission from hydrogen fueled diesel engines.
... The Flame Speed of Hydrogen burning in the air is such greater than the natural gas, and the energy required to initiate the combustion is less. Mixture of hydrogen and air or combustible over an exceptionally wide range of compositions the flammability limits at ordinary temperatures extend from 4% to 74% by volume of hydrogen in air [10][11][12][13]. ...
... N.Saravanan and G.Nagarajan [12] used hydrogen air-gas mixture in dual fuel mode by adopting carburetion, timed out and manifold injection techniques in compression ignition engine. The combustion, performance and emission characteristics compared with baseline diesel operation are presented. ...
The restoration of energy and ecological effect of fossil fuels are hopful interst in the study of alternative fuels for internal combustion (IC) engines. The scope of hydrogen fuel in cupious amount and the near zero pollutants in its combustion are making hydrogen an attractive option. However, strange properties of hydrogen, high flame speed, high calorific value and low density.In this study, a diesel engine is operated using hydrogen diesel dual fuel, where hydrogen is introduced into the intake manifold using an LPG-CNG kit and pilot diesel is injected using diesel injectors. The performance of engine increased when compared with conventaional diesel engine with increased break thermal efficiency and reduced emissions of carbon monoxide (CO), unburn hydrocarbons (HC) and nitrogen oxides (Nox). In this review focused on injection timings, injection duriation, performance and emission charecterstics of hydrogen combustion. Index Terms Hydrogen combustion, Injection timing, emissions of ehgaust, mass fraction of air burn, net heat released rate.
... In the near term, the use of hydrogen in internal combustion engine may be feasible as a low cost technology to reduce emissions. Hydrogen can be adapted in both spark ignition engine and compression ignition engine [3]. The improved volumetric efficiency and the higher heat of combustion of hydrogen compared to gasoline, provides the potential for power density to be approximately 115% that of the identical engine operated on gasoline However, it is worthy to emphasize that while direct injection solves the problem of pre-ignition in the intake manifold, it does not necessarily prevent pre-ignition within the combustion chamber. ...
... We manually changed injection rate from −25% to 25% of the original. The engine system used in the experiment is a 4-cylinder 8-valve commercial engine New Sentra GA16DE, which is a 1600 cm 3 The specific values of input parameters including the AFR, engine speed, and injection timing were defined in the model [16]. Engine specifications for the base engine are tabulated in Table 1. ...
The present study focuses on the effect of air fuel ratio on the performance of hydrogen fueled direct injection internal combustion engine. In the current market, there is some cases that the fueled engine does not perform in optimum condition in which it leads to the problem statement of this study. The primary purpose of this study is to design and develop an optimized fuel engine. Various studies have been conducted in order to improve the existing engine in term of efficiency and environmentally-friendly. Efficiency and environmentally-friendly are the two key factors that the industry looked for in this era globalization whenever selection of engine has been made. According to the study, hydrogen fueled combustion engine is the popular choice among the variety of engine. Other than its outstanding performance, its low lean limit of flammability and ability to reduce power levels by limiting only at the rate at which the fuel is supplied are another reasons why hydrogen fuel engine is widely utilized in the industry. The brake mean effective pressure (BMEP), brake efficiency (BE), brake specific fuel consumption (BSFC) as well as the maximum cylinder temperature is among the parameter which is under monitoring in determination of fuel engine efficiency. With a series of experiment, air-fuel ratio of 35 is believed to enhance the performance of the engine. It is apparent that the developed model can evaluate the engine performance accurately and successfully.
... In the near term, the use of hydrogen in internal combustion engine may be feasible as a low cost technology to reduce emissions. Hydrogen can be adapted in both spark ignition engine and compression ignition engine [3]. The improved volumetric efficiency and the higher heat of combustion of hydrogen compared to gasoline, provides the potential for power density to be approximately 115% that of the identical engine operated on gasoline However, it is worthy to emphasize that while direct injection solves the problem of pre-ignition in the intake manifold, it does not necessarily prevent pre-ignition within the combustion chamber. ...
... We manually changed injection rate from −25% to 25% of the original. The engine system used in the experiment is a 4-cylinder 8-valve commercial engine New Sentra GA16DE, which is a 1600 cm 3 The specific values of input parameters including the AFR, engine speed, and injection timing were defined in the model [16]. Engine specifications for the base engine are tabulated in Table 1. ...
The present study focuses on the effect of air fuel ratio on the performance of hydrogen fueled direct injection internal combustion engine. In the current market, there is some cases that the fueled engine does not perform in optimum condition in which it leads to the problem statement of this study. The primary purpose of this study is to design and develop an optimized fuel engine. Various studies have been conducted in order to improve the existing engine in term of efficiency and environmentally-friendly. Efficiency and environmentally-friendly are the two key factors that the industry looked for in this era globalization whenever selection of engine has been made. According to the study, hydrogen fueled combustion engine is the popular choice among the variety of engine. Other than its outstanding performance, its low lean limit of flammability and ability to reduce power levels by limiting only at the rate at which the fuel is supplied are another reasons why hydrogen fuel engine is widely utilized in the industry. The brake mean effective pressure (BMEP), brake efficiency (BE), brake specific fuel consumption (BSFC) as well as the maximum cylinder temperature is among the parameter which is under monitoring in determination of fuel engine efficiency. With a series of experiment, air-fuel ratio of 35 is believed to enhance the performance of the engine. It is apparent that the developed model can evaluate the engine performance accurately and successfully.
... The study found that when the high pressure selective catalytic reduction reactor is employed, the engine's brake specific fuel consumption (BSFC) increases somewhat but does not surpass 1 g/kWh. The weighted specific NOx emission is 2.09 g/kWh [41,42]. EGR is the most common and cast effective NOx management method for vehicle engines [43]. ...
... Unburned hydrogen may also come out of the engine, but this is not a problem since hydrogen is non-toxic and does not involve in any smog producing reaction. NOx are the most significant emission of concern from a hydrogen engine [9]. ...
This article presents the state-of-the-art research on the hydrogen fueled internal combustion engine. First, the fundamentals of the hydrogen engine are described by studying the engine-specific properties of hydrogen, and then the existing literature is reviewed.
... Saravanan and Nagarajan [151] used carburetor, timing port and manifold injection technology, and dual-fuel induction hydrogen direct injection technology to study the performance and emission characteristics of diesel engine. They found specific energy consumption was reduced by 15 % and smoke was reduced by 18 % in timing port injection. ...
At present, the world petroleum resources are very scarce, and environmental pollution is very serious, which is closely related to the wide application of diesel engines. It encourages researchers to explore more environmentally friendly fuels. In recent years, the research on hydrogen as an alternative fuel has been deepened. Previous studies mostly focused on the influence of hydrogenation on combustion, performance and emission characteristics of internal combustion engines when operating parameters were changed or some technologies were adopted. However, few people have reviewed the combined effects of hydrogen and other alternative fuels on diesel engines. This paper makes an in-depth analysis of the research on the field of alternative fuels in recent years. Firstly, this paper introduces alternative fuels, hydrogen production technology and dual fuel technology. It also highlights the application of hydrogen as an alternative fuel in internal combustion engines. Secondly, the performance, combustion and emission characteristics of diesel engine are analyzed emphatically under dual-fuel mode. Then, the problems of high NOx emission and limited hydrogen energy share in the current dual-fuel engine research are also discussed. In addition, this paper also expounds the technology of homogeneous charge compression ignition (HCCI) strategy, water injection strategy and compression ignition to alleviate the shortcomings of diesel-hydrogen dual fuel engine. The purpose of this paper is to provide information for engineers and researchers interested in hydrogen. This paper summarizes a large number of high-quality journal literature, including the latest publications.
... This could support the development of a rened 'most likely' outcome for NO x emissions, which alongside real-world testing, may help to determine whether hydrogen-specic NO x standards and therefore additional aertreatment technologies are required. [103][104][105] A larger range of studies would be needed for this analysis if uncertainties in projections were to be narrowed. ...
As countries seek ways to meet climate change commitments, hydrogen fuel offers a low-carbon alternative for sectors where battery electrification may not be viable. Blending hydrogen with fossil fuels requires only modest technological adaptation, however since combustion is retained, nitrogen oxides (NOx) emissions remain a potential disbenefit. We review the potential air quality impacts arising from the use of hydrogen–diesel blends in heavy-duty diesel engines, a powertrain which lends itself to hydrogen co-fuelling. Engine load is identified as a key factor influencing NOx emissions from hydrogen–diesel combustion in heavy-duty engines, although variation in other experimental parameters across studies complicates this relationship. Combining results from peer-reviewed literature allows an estimation to be made of plausible NOx emissions from hydrogen–diesel combustion, relative to pure-diesel combustion. At 0–30% engine load, which encompasses the average load for mobile engine applications, NOx emissions changes were in the range −59 to +24% for a fuel blend with 40 e% hydrogen. However, at 50–100% load, which approximately corresponds to stationary engine applications, NOx emissions changes were in the range −28 to +107%. Exhaust gas recirculation may be able to reduce NOx emissions at very high and very low loads when hydrogen is blended with diesel, and existing exhaust aftertreatment technologies are also likely to be effective. Recent commercial reporting on the development of hydrogen and hydrogen–diesel dual fuel combustion in large diesel engines are also summarised. There is currently some disconnection between manufacturer reported impacts of hydrogen-fuelling on NOx emissions (always lower emissions) and the conclusions drawn from the peer reviewed literature (frequently higher emissions).
... The efficiency of SCR in reducing NOx emissions are about 80e90% [145]. SCR system with diesel-hydrogen dual-fuel combustion in CI engine is effective in reducing the NOx emissions to a greater extent without affecting the engine performance [146]. In summary, SCR is more effective in NOx emissions reduction, especially with hydrogen induction. ...
Compression ignition (CI) engines used in the transportation sector operates on fossil diesel and is one of the biggest causes of air pollution. Numerous studies were carried out over last two decades to substitute the fossil diesel with biofuels so that the net carbon dioxide (CO2) emission can be minimized. However, the engine performance with these fuel was sub-standard and there were many long-term issues. Therefore, many researchers inducted hydrogen along with the biofuels. The present study gives an outlook on the effect of hydrogen addition with biodiesel/vegetable oil from various sources in CI engine. Engine parameters (brake thermal efficiency, brake specific fuel consumption), combustion parameters (in-cylinder pressure and heat release rate) and emission parameters (unburned hydrocarbon (HC), carbon monoxide (CO), oxides of nitrogen (NOx) and smoke emissions) were evaluated in detail. The results show that hydrogen induction in general improves the engine performance as compared to biodiesel/vegetable oil but it is similar/lower than diesel. Except NOx emissions all other emissions showed a decreasing trend with hydrogen addition. To counter this effect numerous after-treatment systems like selective catalytic reduction (SCR), exhaust gas recirculation (EGR), selective non-catalytic reduction system (SNCR) and non-selective catalytic reduction system (NSCR) were proposed by researchers which were also studied in this review.
... Details regarding alternative fuels challenges are going to be developed in the next section. H 2 when burned in this engine generates by-products [36], and limiting its consideration to get a ZES yet from a transitional perspective is an option to reduce emissions from shipping. ...
Due to the increasing impact of ship emissions on the environment and the preventive mea- sures of current regulations introduced by the International Maritime Organization to significantly reduce them, the development of ocean-going all-electric ships has been addressed as a concept applied to achieve it. Being a promising technology considers the use of technology alternatives such as fuel cells, batteries, and supercapacitors together with the use of zero-carbon alternative fuels such as hydrogen (H2) and ammonia (NH3) as main energy sources. This article addresses a state-of-the-art on several challenges related to the ocean-going zero-emissions ship to achieve a zero-emissions shipping, based on the technology associated with hybrid and all-electric ship, and the zero-carbon fuels alternatives. In this respect, a transition from fossil fuel-based propulsion and auxiliary systems to a zero-emissions ship concept are related to the challenges to overcome the needs of energy density for these new alternatives energy sources compared to current fossil fuel options. The transitional process should consider a first step of hybridization of the propulsion and auxiliary systems of existing ships to get a baseline from where to move forward to a zero-emissions configuration for new designs.
... Another option is to implement a selective catalytic reaction (SCR) system. There have been ongoing several research on this topic as TWC is not feasible at lean operating conditions in SI engines [9,42,43,44,45,46,47]. However, it will not be discussed in detail in the current study. ...
The hydrogen internal combustion engine (H2ICE) has received increasing attention in various industry sectors as it produces nearly zero carbon emissions.
However, it has been reported that the power output is lower than the gasoline engine especially for port fuel injection (PFI) type hydrogen engines. It is mainly due to low density of the hydrogen which reduces volumetric efficiency. A turbo- charging system can improve the power output by pushing more air into the combustion chamber. However, it was observed that incorrect matching hampers the increment of the power output which results in low specific power (<30kW/L). To achieve the equivalent performance of a turbo- charged PFI gasoline engine, the required boosting system for the PFI H2ICE has been numerically investigated using
1D engine simulation. As a base engine, a 1.6L turbocharged PFI gasoline engine was used. The validated base engine model was modified for the hydrogen operation and the simulation was carried out at wide open throttle (WOT) from 1000 to 4000 RPM under the equivalence ratio (ϕ) of 0.55. It was iden- tified that the PFI H2ICE requires 50% higher mass flow and 90% higher boost pressure against the turbocharged gasoline engine. A single-stage charging system is not able to supply the required boost and mass flow over the wide range of opera- tion. Instead, a two-stage boosting system with VGT at high pressure stage could deliver such a high boost and mass flow. The boost and mass flow demand are mainly influenced by the operational lambda (λ) and target performance which should be considered in designing the boosting system for the PFI SI type H2ICE.
... Properties of diesel and hydrogen[34] ...
In this work, a thermodynamic model is used to analyze the influence of some usual engine parameters such as compression ratio, ambient temperature, turbocharger compressor pressure ratio, equivalence ratio, and engine speed on the performances of a diesel–hydrogen dual-fuel marine engine. The model takes into consideration the change in the composition of the working fluid resulting from the combustion cycle as well as the reactive mixture. This model considers also the dependence of the working fluid specific heat on temperature. Results show that the increase in the equivalence ratio yields to an improvement of the brake specific fuel consumption, the brake power output, the brake thermal, and exergy efficiencies with an increase in the exhaust gas temperature. Nevertheless, it produces a drop in volumetric efficiency. The engine speed has a slight effect on the brake thermal efficiency, exergy efficiency, and the brake specific fuel consumption. The engine speed affects the engine power output mainly at higher values of the fuel–air equivalence ratio due to the reduction in heat losses and the fuel energy consumed by the engine. The increase in the turbo-compressor pressure ratio has a significant effect on the improvement of engine performance. However, it has an insignificant effect on the exhaust gas temperature. The exergy destroyed in the engine dominates. It accounts for 88.2% of the total exergy destroyed in the overall system. The remaining components (turbo-compressor, intercooler, mixer, catalytic converter, and turbine) are responsible for only 11.2%.
... LPG-fueled dual fuel mode reduces the smoke formation. This is due to lower molecular weight, smaller C/C bonds (Miller Jothi, Nagarajan, and Renganarayanan 2007) and absence of carbon molecules (Saravanan and Nagarajan 2009). With the addition of hydrogen along with LPG and MO smoke emission decreased from 84% with 0 lpm HLPG to 10% with 11 lpm HLPG. ...
In this paper, the effects of hydrogen-blended LPG on performance, combustion, and emission behavior of mahua oil-fueled dual fuel engine were experimentally investigated and presented. Mahua oil (pilot fuel) was directly injected into the cylinder during compression stroke and gaseous fuels LPG and HLPG (primary fuel) was inducted into the intake manifold during suction stroke of the engine with variable flow rates such as 1,2,3, and 4 lpm (liter per minute) at 1-lpm interval. The investigation was carried out on diesel engine at speed of 1500 rpm with 3.7 kW rated power output. The following inferences were made from the experimental investigation. Brake thermal efficiency of the engine decreases for alternate fuel (neat mahua oil) mode of operation compared to conventional diesel fuel operation. On the other hand, brake thermal efficiency of neat mahua oil increases from 28% with single fuel operation to 29.3% under 5 lpm LPG dual fuel operation. Further improvement in brake thermal efficiency is noted when 1 lpm hydrogen is mixed with LPG flow. Eighty-three percent reduction in HC emission is observed for 11 lpm HLPG compared with 10 lpm LPG. Massive reduction in smoke formation is perceived for both LPG and HLPG flow rates. But NO emission is increased for both LPG and HLPG fuels compared to neat mahua oil. As a final point, the study abstracts that performance of the neat mahua oil-based compression ignition engine has been increased under dual mode by adding LPG and hydrogen.
... This is due to the admission of a higher amount of gaseous fuel and the corresponding reduction in RSO. Also, LPG has lower carbon to hydrogen ratio [29]. In addition, the molecular weight of LPG is low and the carbon-carbon bond is smaller in number [30] resulting in lowering of smoke levels. ...
In the present work, liquefied petroleum gas (LPG) is premixed with air for combustion in a compression ignition engine, along with neat rubber seed oil as the direct injected fuel. The LPG is injected directly into the intake manifold using an electronic gas injector. The variation in the LPG flow rate is from zero to the maximum tolerable value. The engine load was varied from no load to full load at regular intervals of 25% of full load. Experimental results indicate a reduction in thermal efficiency at low loads, followed by a small improvement in the thermal efficiency at 75% and 100% loads. Premixing of LPG prolongs the delay in the ignition with a simultaneous decrease in the duration of combustion. With an increase in the LPG flow rate, the maximum in-cylinder pressure increased at high outputs, whereas it decreased at low outputs. The heat release rate shows that the combustion rate increases with LPG induction. Carbon monoxide (CO) and hydrocarbon (HC) levels reduced at high outputs, whereas at all loads, the oxides of nitrogen (NOx) levels increased. The NOx level at full load increased from 6.9 g/kWh at no LPG induction to 10.36 g/kWh at 47.63% LPG induction. At all loads, the smoke level decreased drastically. The smoke level at full load decreased from 6.1BSU at no LPG induction to 3.9BSU at 47.63% LPG induction.
... Different hydrogen addition techniques and various fuel blends have been investigated and evaluated by many researchers in terms of engine performance, combustion, and emission characteristics. Saravanan and Nagarajan [15], studied hydrogen-diesel dual-fuel engine injection techniques. Fuel injected from 5-mm and 100-mm distance in front of the intake valve, which were defined as port and manifold injection techniques, respectively. ...
In this study, the effects of hydrogen addition on diesel-biodiesel-butanol fuel blends were investigated in terms of engine performance, combustion, and emission characteristics under different engine operating conditions. The experiments were performed with eight different fuel blends at a constant engine speed of 2000 rpm, which is the maximum torque value of all test fuels. The four operating conditions were at 25%, 50%, 75%, and 100% engine loads. Hydrogen was delivered to diesel-biodiesel-butanol fuel blends through the intake manifold with different rates of fuel mass consumption. The experiment results were compared with euro diesel and absence of hydrogen addition for all test fuels. The experimental results have revealed that at 2000 rpm engine speed, the brake torque, in-cylinder pressure, and exhaust gas temperature increased with the addition of hydrogen. Nevertheless, the brake-specific fuel consumption, carbon monoxide (CO), carbon dioxide (CO2), hydrocarbon (HC), nitrogen oxides (NOx), and smoke opacity emissions decreased under various engine conditions. The heat release rate was generally shown to be decreased with higher engine loads and increased with lower engine load conditions, while a rise in thermal efficiency was observed. Therefore, the addition of hydrogen in a diesel engine usually exhibited fewer emissions, improved the combustion process, and increased the brake torques of the engine by comparison to the absence of hydrogen addition.
... The hydrogen was inducted into the engine combustion chamber by using a gas carburetor at a constant rate of 10 lpm. The gas carburetor was used to get a readily available mixture of air and hydrogen due to its simplest delivering method (Saravanan and Nagarajan 2009). Before being inducted into the intake manifold, the gaseous fuel pass through the flame tap to extinguish the explosion or fire and making the system safer to operate. ...
Gaseous fuel as a combustion enhancer with a pilot fuel offers significant benefits in improving engine efficiency. Hydrogen and hydroxy are the two most common gaseous fuels that have been widely investigated in the CI engine but which one performs best is still inconvenient. In this study, hydrogen and hydroxy were injected with BD40 (v/v) separately in a common diesel engine to compare the performance and emission characteristics of these fuels. Engine performance parameters include brake thermal efficiency (BTE) and brake-specific energy consumption (BSEC), and exhaust emissions include hydrocarbon (HC), CO, CO2, NOx, and smoke opacity. The induction of both hydroxy and hydrogen with BD40 has a positive effect on engine performance and emissions except NOx when compared to neat diesel fuel and BD40. The BTE of hydroxy-rich BD40 increased by 7.2% while BSEC reduced by 7.6% as compared to BD40 with hydrogen. The CO, HC, and smoke opacity of hydroxy-operated engine was found to be better than hydrogen-inducted engine. The NOx emission increased with the induction of both gaseous fuels and hydroxy-enriched BD40 produced 12.5% more emission than hydrogen-operated BD40 engine. Thus, more concisely, hydroxy-operated biodiesel engine performed better than hydrogen engine in terms of BTE, BSEC, CO, HC, and smoke opacity.
... Different studies have used different secondary gaseous fuels, for example, producer gas [4], methane [5], hydrogen [6], LPG [2] etc. A study based on the experimental data for a homogeneous charge compression ignition (HCCI) engine fuelled with 85% iso-octane and 15% nheptane, evaluated two zero-dimensional codes used in the simulation of internal combustion engine (ICE) and concluded that each code had an advantage over the other with the advantages of the stochastic reactor model software leading to a better convergence of results [7]. ...
Improvements in life expectancy and standards of living, along with population growth, have contributed to the depletion of the planet's traditional energy sources. Such current dependence suggests that fossil fuels will continue to dominate the powering of internal combustion engines. Nevertheless, because of their adverse environmental impacts, stringent environmental legislation is in place today to regulate industries which use conventional fossil fuels. Hence, there is the necessity to seek viable, sustainable alternatives to power diesel engines. Therefore in this study, performance and emission characteristics are investigated using a diesel engine modified to function in dual-fuel mode (with diesel and liquefied petroleum gas). Engine cylinder pressure is obtained experimentally. A single-zone, zero-dimensional model is then developed and validated under different engine operating conditions. The performance and emission characteristics of the retrofitted diesel engine are investigated and analysed for various diesel-LPG ratios. The study reveals that, generally, the higher the engine speed, the higher the maximum in-cylinder pressure and vice versa. Also, increasing the LPG mass fraction from 50% to 60% at each operating regime, will lead to improvement in engine performance (efficiency, power, torque) and reduce NOx and HC emissions.
... Unburned hydrogen may also come out of the engine, but this is not a problem since hydrogen is non-toxic and does not involve in any smog producing reaction. NOx are the most significant emission of concern from a hydrogen engine [9]. ...
... The gaseous fuel, such as gasification gas, hydrogen, or natural gas, is mixed with air and carbureted into the air intake. The mixture is then compressed inside the combustion chamber similar to the normal CI engines, and it is combusted after injecting a small amount of pilot fuel at the end of the compression stage (Lambe and Watson 1992;Bika et al. 2009;Saravanan and Nagarajan 2009). The combustibility of the two used fuels in the dual fuel mode provides substantial energy with stable ignition. ...
Simulated syngas produced from biomass gasification was evaluated in a compression ignition (CI) engine under a dual fueling mode. Syngas is an economical solution with a carbon-neutral system that could replace petroleum diesel fuel. Syngas can be introduced into CI engines through a dual fueling process. However, syngas dual fueling combustion is very complicated because it consists of several combustion phases. In addition, CI engines operating under the syngas dual fueling mode suffer from low performance. Therefore, this study examined the performance of syngas dual fueling in a CI engine with blended biodiesel as pilot fuel. Two types of simulated syngas, namely typical syngas and high hydrogen syngas, were considered. The simulated high hydrogen syngas was assumed to be the product of biomass gasification with introduction of a carbon dioxide adsorption. The effect of carbon dioxide removal from syngas on the performance of syngas dual fueling in a CI engine at constant engine speed, half load, and different pilot fuel substitution rates was investigated. The combustion characteristics showed a maximum pilot fuel substitution of up to 47% with simulated syngas. Better engine performance was achieved with the simulated typical syngas in terms of brake specific energy consumption and brake thermal efficiency.
... To increase activity at low temperature can be possible to use different reductants or additives. H 2 has been used in many studies as an alternative fuel for internal combustion engines to eliminate pollutant emissions and improve engine performance [23,24]. The combustion of hydrogen in combustion chamber has improved activity of SCR systems enhancing NO 2 /NO x ratios [25]. ...
Diesel engines have been considered as a major source in nitrogen oxide (NOx) formation worldwide. The widespread use of diesel engines in consequence of their low fuel consumption, high durability and efficiency increases NOx emissions day by day. NOx emissions from diesel engines cause unavoidable damage on environment and people health. Although so many technologies such as exhaust gas recirculation (EGR), lean burn combustion, electronic controlling fuel injection systems, etc. have been developed to control NOx emissions from diesel engines, they couldn't meet the desired reduction in NOx emissions. In any case, Selective Catalytic Reduction (SCR) as one of the most promising aftertreatment-emission control technologies is an effective solution in restriction of NOx emissions. The use of SCR systems especially in heavy-duty diesel powered vehicles has been increasing nowadays. In these systems, to use of hydrogen (H2) as a reductant or promoter have been improved the conversion efficiency especially at low exhaust temperatures. Many researchers have been focused on the use of H2 in SCR systems for controlling NOx emissions.
... Unburned hydrogen may also come out of the engine, but this is not a problem since hydrogen is non-toxic and does not involve in any smog producing reaction. NOx are the most significant emission of concern from a hydrogen engine [9]. ...
The present scenario of the automotive and agricultural sectors is fairly scared with the depletion of fossil fuel. The researchers are working towards to find out the best replacement for the fossil fuel; if not at least to offset the total fuel demand. In regards to emission, the fuel in the form of gaseous state is much than liquid fuel. By considering the various aspects of fuel, hydrogen is expected as a best option when consider as a gaseous state fuel. It is identified as a best alternate fuel for internal combustion engines as well as power generation application, which can be produced easily by means of various processes. The hydrogen in the form of gas can be used in the both spark ignition and compression ignition engines for propelling the vehicles. The selected fuel is much cleaner and fuel efficient than conventional fuel. The present study focusing the various aspects and usage of hydrogen fuel in S.I engine and C.I engine
... emissions mitigation, as simple installations such like three way catalytic converters are not efficient during lean operation. For this reason, selective catalytic reduction (SCR) systems are used, with very high efficiency, but also much more expensive (Saravanan & Nagarajan, 2009 From ignition to completion, combustion was divided into three separate processes. The first phase was considered as a constant pressure increase (dp) rapid combustion, the second an isobaric process at maximum pressure ([p.sub.max]), and finally a slow burn phase, considered as an isothermal process, at maximum temperature ([T.sub.max]). ...
Converting compression ignition engines to run on biogas raises specific problems that need to be addressed before undergoing such transformations. A theoretical study was developed for evaluating various factors when considering the conversion of a heavy duty diesel engine to biogas fuelling in an installation featuring cogeneration of heat and power. Required biogas flow was calculated and other necessary modifications are covered by the paper, so that stable operation can be obtained, with a high overall thermal efficiency.
... Hence, the uncertainties in BSFC and BTE are based on the root mean square of the uncertainties of relevant measurable parameters. The uncertainties in BSFC and BTE for fuel blend B10-ZnO20 nm at an H 2 flowrate of 0.5 L/min are evaluated (Holman, 2012;Saravanan and Nagarajan, 2009) and are presented in Table 4. Appendix B shows the formulations with a sample calculation. At a 95% probability level (Figliola and Beasley, 2015), the uncertainties in the measurable and computed parameters for fuel blend B10-ZnO20 nm at an H 2 flowrate of 0.5 L/min for an engine load of 0.5 kW range from 0.15% to 3% (Tables 3 and 4). ...
Emissions from a Direct Injection (DI) diesel engine can be reduced by the addition of metallic fuel-borne additives. However, the effect of fuel-borne catalysts in a dual fuel engine with hydrogen (H2) as a secondary fuel is not well known. Hence, experimentation was carried out to investigate the effects of nano-metallic oxide fuel additives on the major physicochemical properties and performance of jatropha biodiesel blends in a DI diesel engine in dual fuel mode. Jatropha methyl ester (JME) biodiesel is produced from degummed crude jatropha oil after reducing the free fatty acid (FFA) content to less than 2% and performing transesterification using a 20 kHz frequency ultrasonicator with a sodium hydroxide (NaOH) catalyst. Zinc oxide (ZnO) nanoparticles at 100 ppm with a size of 20 and 40 nm were suspended in primary fuel of JME biodiesel. H2 as a secondary fuel with flowrates of 0.5 and 1.5 L/min was maintained during the experiments. The experimental results reveal that the nanoparticle size influences the engine performance and emissions. The presence of nanoparticles in the fuel blends reduced the nitrogen oxide (NOx) emissions. However, the effects of the size and concentration were marginal with an increasing H2 flowrate. With an increasing H2 flow rate, hydrocarbon (HC) emissions decreased for nanoparticles of size 20 nm, but increased for 40 nm. Smoke opacity was increased compared with pure biodiesel owing to the presence of surfactant Triton-X100.
... One alternative fuel to carbon-based fuels is hydrogen [1]. In the near term, the use of hydrogen in internal combustion engine may be feasible as a low cost technology to reduce emissions [2]. The in-cylinder gas flow characteristics have major influence on combustion process, fuel consumption, emission production and engine performance [3,4]. ...
Internal combustion engines continue to dominate in many fields like transportation, agriculture and power generation. Among the various alternative fuels, hydrogen is a long-term renewable and less polluting fuel (Produced from renewable energy sources). In the present experimental investigation, the performance and emission characteristics were studied on a direct injection diesel engine in dual fuel mode with hydrogen inducted along with air adopting carburetion, timed port and manifold injection techniques. Results showed that in timed port injection, the specific energy consumption reduces by 15% and smoke level by 18%. The unburnt hydrocarbons and carbon monoxide emissions are lesser in port injection. The oxides of nitrogen are higher in hydrogen operation (both port and manifold injection) compared to diesel engine. In order to reduce the NOX emissions, a selective catalytic converter was used in hydrogen port fuel injection. The NOX emission reduced upto a maximum of 74% for ANR (ratio of flow rate of ammonia to the flow rate of NO) of 1.1 with a marginal reduction in efficiency. Selective catalytic reduction technique has been found to be effective in reducing the NOX emission from hydrogen fueled diesel engines.
... Unburned hydrogen may also come out of the engine, but this is not a problem since hydrogen is non-toxic and does not involve in any smog producing reaction. NOx are the most significant emission of concern from a hydrogen engine [9]. ...
The danger posed by climate change and the striving for securities of energy supply are issues high on the political agenda these days. Governments are putting strategic plans in motion to decrease primary energy use, take carbon out of fuels and facilitate modal shifts. Man's energy requirements are touching astronomical heights. The natural resources of the Earth can no longer cope with it as their rate of consumption far outruns their rate of regeneration. The automotive sector is without a doubt a chief contributor to this mayhem as fossil fuel resources are fast depleting. The harmful emissions from vehicles using these fuels are destroying our forests and contaminating our water bodies and even the air that we breathe. The need of the hour is to look not only for new alternative energy resources but also clean energy resources. Hydrogen is expected to be one of the most important fuels in the near future to meet the stringent emission norms. The use of the hydrogen as fuel in the internal combustion engine represents an alternative use to replace the hydrocarbons fuels, which produce polluting gases such as carbon monoxide (CO), hydro carbon (HC) during combustion. Developing countries like India in particular are pushing for research and development of Hydrogen fuelled internal combustion engines (H2ICEs), powering two- and three-wheeler as well as passenger cars and buses to decrease local pollution at an affordable cost. This article offers a comprehensive overview of developing a dedicated hydrogen port injection kit to run a conventional 170 cc SI Engine on Hydrogen only. The comprehensive assessment was done to investigate the effects of hydrogen fuel compositions variation on brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), Exhaust gas temperature, Unburned Hydrocarbon emission (UHC), Carbon monoxide Emission (CO), Oxides of nitrogen emission (NOx) and Smoke opacity. Also, the measures taken to prevent knocking and ensure smooth running of hydrogen engine have been discussed.
... Unburned hydrogen may also come out of the engine, but this is not a problem since hydrogen is non-toxic and does not involve in any smog producing reaction. NOx are the most significant emission of concern from a hydrogen engine [9]. ...
... emissions mitigation, as simple installations such like three way catalytic converters are not efficient during lean operation. For this reason, selective catalytic reduction (SCR) systems are used, with very high efficiency, but also much more expensive (Saravanan & Nagarajan, 2009 From ignition to completion, combustion was divided into three separate processes. The first phase was considered as a constant pressure increase (dp) rapid combustion, the second an isobaric process at maximum pressure ([p.sub.max]), and finally a slow burn phase, considered as an isothermal process, at maximum temperature ([T.sub.max]). ...
Converting compression ignition engines to run on biogas raises specific problems that need to be addressed before undergoing such transformations. A theoretical study was developed for evaluating various factors when considering the conversion of a heavy duty diesel engine to biogas fuelling in an installation featuring cogeneration of heat and power. Required biogas flow was calculated and other necessary modifications are covered by the paper, so that stable operation can be obtained, with a high overall thermal efficiency.
... Dual fuel operation reduces the amount of pilot diesel fuel during diffusion-controlled combustion phase. Further, the initiation of combustion and longer period of premixed combustion phase may result in higher nitric oxide emissions due to higher in cylinder temperature [27]. It is observed that the NO x emission in Case IV is more than Case II and III due to higher mean gas temperature (Fig. 8). ...
Energy is an essential prerequisite for economical and social growth of any country. Skyrocketing of petroleum fuel cost s in present day has led to growing interest in alternative fuels like CNG, LPG, Producer gas, Biogas in order to provide suitable substitute to diesel for a compression ignition engine. This paper discusses some experimental investigations on dual fuel operation of a 4 cylinder (turbocharged and intercooled) 62.5 kW gen-set diesel engine with hydrogen, producer gas (PG) and mixture of producer gas and hydrogen as secondary fuels. Results on brake thermal efficiency and emissions, namely, un-burnt hydrocarbon (HC), carbon monoxide (CO), and NOx are presented here. The paper also contains vital information relating to the performances of an engine at a wide range of load conditions with different gaseous fuel substitutions. When only hydrogen is used as secondary fuel, maximum increase in the brake thermal efficiency is 7% which is obtained with 20% of secondary fuel. When only producer gas is used as secondary fuel, maximum decrease in the brake thermal efficiency of 8% is obtained with 30% of secondary fuel. Compared to the neat diesel operation, proportion of un-burnt HC and CO increases, while, emission of NOx reduces in all Cases. On the other hand, when 40% of mixture of producer gas and hydrogen is used (in the ratio (60:40) as secondary fuel, brake thermal efficiency reduces marginally by 3%. Further, shortcoming of low efficiency at lower load condition in a dual fuel operation is removed when a mixture of hydrogen and producer gas is used as the secondary fuel at higher than 13% load condition. Based on the performance studied, a mixture of producer gas and hydrogen in the proportion of 60:40 may be used as a supplementary fuel for diesel conservation.
... A hydrogen injection electronic control unit (ECU) was developed to operate a diesel engine operating in dual fuel mode using diesel oil and hydrogen [3,12]. The ECU allowed for tests varying the injection timing and the hydrogen mass injected. ...
This work presents an electronic control system developed for hydrogen injection in a diesel power generator. The full system is basically constituted by a gas fuel injection rail with injection valves, a speed sensor and an electronic control unit. The electronic injection system was installed and tested in a diesel power generator of 44 kW rated power. The tests were carried out with hydrogen injected in the intake manifold and diesel oil directly injected in the combustion chamber. The results show the injection valve opening periods necessary to obtain hydrogen mass flow rates equivalent to 5%, 10%, 15% and 20% of the diesel oil mass replaced. The measured hydrogen mass flow rate injected is presented as a function of load power demand and hydrogen concentration in the fuel.
The urgent need for decarbonization and emission reduction for marine engines is driving the development of alternative low-carbon fuels. One of the best alternative fuels for engines is natural gas, a clean energy source with vast reserves and a low price. However, low-pressure injection dual-fuel engines exhibit poor combustion characteristics at low engine loads, and extinction is likely to occur in the fuel mixture's dilution region. Thus, the Low Pressure Post Injection (LPPI) strategy was proposed in this paper. The major objective of the LPPI mode is to increase monocirculation combustion stability under low to moderate engine loads by achieving a reasonable distribution of NG in the combustion chamber. LPPI was compared with the Low Pressure Injection (LPI) strategy. Results indicate that the LPPI mode could successfully raise the swirl ratio in the cylinder up to 60.7 percent while perfectly avoiding the NG leakage phenomena. Additionally, with the aid of radial-wall distribution of NG and an improved swirl ratio in LPPI mode, the combustion duration is reduced by 33.6 percent, and the lean burn limit of the dual-fuel marine engine can be expanded to 0.30. Although local higher combustion temperature caused an large increase in NOx emission which is more than three times than LPI NOx emission, LPPI mode still meets Tier III NOx emission requirements.
The presented work concerns experimental research of a spark-ignition engine with variable compression ratio (VCR), adapted to dual-fuel operation, in which co-combustion of ammonia with hydrogen was conducted, and the energy share of hydrogen varied from 0% to 70%. The research was aimed at assessing the impact of the energy share of hydrogen co-combusted with ammonia on the performance, stability and emissions of an engine operating at a compression ratio of 8 (CR 8) and 10 (CR 10). The operation of the engine powered by ammonia alone, for both CR 8 and CR 10, is associated with either a complete lack of ignition in a significant number of cycles or with significantly delayed ignition and the related low value of the maximum pressure pmax. Increasing the energy share of hydrogen in the fuel to 12% allows to completely eliminate the instability of the ignition process in the combustible mixture, which is confirmed by a decrease in the IMEP uniqueness and a much lower pmax dispersion. For 12% of the energy share of hydrogen co-combusted with ammonia, the most favorable course of the combustion process was obtained, the highest engine efficiency and the highest IMEP value were recorded. The conducted research shows that increasing the H2 share causes an increase in NO emissions, for both analyzed compression ratios.
The hydrogen economy requires the right conditions to produce hydrogen by sustainable routes and provide it to local and international markets for suitable applications. This study evaluated the political, economic, social, technological, legal, and environmental (PESTLE) conditions that can be instrumental in adopting hydrogen technologies most effectively by encapsulating aspects relevant to key stakeholders from hydrogen technology developers through to end-users. For instance, the analysis has shown that countries within a government effectiveness index of 0.5 and −0.5 are leading the planning of hydrogen economies through strategic cooperation with hydrogen technology developers. Furthermore, the combination of a Doughnut and PESTLE analysis created a novel approach to assessing the adoption of hydrogen technologies while evaluating the impact of the hydrogen economy. For instance, the estimated ammonia demand in 2050 and subsequent anthropogenic nitrogen extraction rate will be about two and a half times more than the 2009 extraction rate.
In this study, low temperature activity of Ag–Ti–Cu/Cordierite catalyst was investigated with liquefied petroleum gas (LPG) and hydrogen-liquefied petroleum gas (H2-LPG) mixture as reductant. The selective catalytic reduction (SCR) catalyst was synthesized by impregnation method and characterized by Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analyzes. BET analysis of the catalyst revealed surface area as 12.89 m²/g. Silver (Ag), titanium (Ti) and copper (Cu) nanoparticles were observed on the catalyst surface with SEM analysis. XRD analysis showed high dispersion of catalytic elements. The SCR performance tests were carried out at 170–270 °C temperature range, 30,000 h⁻¹ and 40,000 h⁻¹ space velocities, 1 kW, 2 kW, 3 kW and 4 kW engine loads with diesel engine real exhaust gas sample. NOx conversion efficiency increased significantly in the presence of H2, especially at low exhaust temperatures. The maximum NOx conversion ratio was obtained as 89.53% with H2-LPG reductant at 270 °C, 4 kW engine load and 30,000 h⁻¹ space velocity.
The utilization of gaseous fuels in internal combustion (IC) engines is receiving more significant greater interest in recent years because of their better fuel mixing characteristics. Apart from potential gaseous fuels such as liquefied natural gas (LPG), compressed natural gas (CNG), and hydrogen, other alternatives are being explored for their utilization in IC engines. The reason for this exploration is mainly because of the durability and robust nature of compression ignition (CI) engines, and more research focuses on the utilization of a variety of gaseous fuels in CI engines. However, gaseous fuels need to be used in CI engines on dual fuel mode only. In this investigation, a single-cylinder, four-stroke, air-cooled diesel engine was converted into Acetylene run dual fuel CI engine by changing the intake manifold of the test engine. Acetylene at three flow rates viz., 2lpm, 4lpm, and 6lpm were introduced into the intake port by manifold induction technique while Jatropha biodiesel/diesel was injected directly into the cylinder. In this paper, the effect of manifold induction of Acetylene on the performance and emission characteristics of the test engine was assessed and compared with those of conventional diesel operation of the test engine.
Selective catalytic reduction of nitrogen oxides with loaded CH4N2O (low-temperature urea-SCR) is a novel and promising technology to remove nitrogen oxides from low-temperature oxygen-containing flue gas, which can avoid the problem of NH 3 escape. In the present study, a series of industrial-grade biomass-based activated carbon (AC)-supported transition metal oxide catalysts with urea loading were prepared by ultrasound-assisted impregnation, and the physicochemical properties of the catalysts were observed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), graphite furnace atomic absorption spectroscopy (GFAAS), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) analysis, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The influences of the AC type, reaction temperature, AC particle size, metal oxide loading, urea load level and loaded active element type on the catalytic activity were studied through experiments. Moreover, the NO adsorption capacities of the AC carrier at different temperatures were also tested and calculated. The results of NO adsorption tests show that the adsorption capacity of AC decreased with increasing temperature. The results of the catalytic performance tests indicate that the copper- and manganese-based catalysts with 6 wt% urea exhibited better activity than the other catalysts. The copper-based catalyst, in particular, yielded better than 93% NO conversion at low temperatures (50–100 °C). Finally, on the basis of the combined characterization results and thermodynamics analysis, a NO removal mechanism of the copper- and manganese-based catalysts was proposed and discussed; the electron transfers of Mn ⁴⁺ ⇌ Mn ²⁺ and Cu ²⁺ ⇌ Cu ⁰ promoted the low-temperature urea-SCR method.
This paper focuses on optimizing the hydrogen TMI (timed manifold injection) system through valve lift law and hydrogen injection parameters (pressure, injection inclination and timing) in order to prevent backfire phenomena and improve the volumetric efficiency and mixture formation quality of a dual fuel diesel engine operating at high load and high hydrogen energy share. This was achieved through a numerical simulation using CFD code ANSYS Fluent, developed for a single cylinder hydrogen-diesel dual fuel engine, at constant engine speed of 1500 rpm, 90% of load and 42.5% hydrogen energy share. The developed tool was validated using experimental data. As a results, the operating conditions of maximum valve lift = 10.60 mm and inlet valve closing = 30 °CA ABDC (MVL10 IVC30) prevent the engine from backfire and pre-ignition, and ensure a high volumetric efficiency. Moreover, a hydrogen start of injection of 60 °CA ATDC (HSOI60) is appropriate to provide a pre-cooling effect and thus, reduce the pre-ignition sources and helps to quench any hot residual combustion products. While, the hydrogen injection pressure of 2.7 bar and an inclination of 60° stimulate a better quality of hydrogen-air mixture. Afterwards, a comparison between combustion characteristics of the optimized hydrogen-diesel dual fuel mode and the baseline (diesel mode) was conducted. The result was, under dual fuel mode there is an increase in combustion characteristics and NOx emissions as well as a decrease in CO2 emissions. For further improvement of dual fuel mode, retarding diesel start of injection (DSOI) strategy was used.
This study investigates the combustion and emissions of a compression ignition (CI) engine operating with mixtures of hydrogen (H2) and carbon monoxide (CO) injected with the intake air. Hydrogen and carbon monoxide were chosen as the gaseous fuels, because they represent the main fuel component of synthesis gas, which can be produced by a variety of methods and feed stocks. However, due to varying feed stock and production mechanisms, syngas composition can vary significantly. It is currently unknown how a varying H 2/CO (syngas) ratio affects the cycle efficiency and gaseous emissions. The experiments were performed on an air-cooled, naturally aspirated, direct injection diesel engine. The engine was operated at 1800 RPM with a compression ratio of 21.2:1. Two load conditions were tested; 2 bar and 4 bar net indicated mean effective pressure (IMEPn). For all test conditions the added syngas demonstrated lower cycle efficiency than the diesel fuel baseline. The lower cycle efficiency is thought to directly come from the amount of unburned syngas escaping with the exhaust gases. For the 2 bar IMEPn condition the NOx emissions remained relatively constant for all conditions tested, however for the 4 bar IMEPn condition, the NOx emissions increased with diesel fuel substitution for all H2/CO proportions. The NO2/NOx ratio was found to significantly increase for all conditions tested, compared to the diesel base case. It is speculated that this increase is caused by the increase in HO2 radicals which increases the NO to NO2 conversion.
The mechanism of abnormal combustion of hydrogen fueled engines was discussed in this paper for controlling abnormal combustion of hydrogen fueled engines, and providing references to resolve the contradiction between abnormal combustion and power output. Moreover, the relationship between pre-ignition of hydrogen fueled engine and its pressure rise rate was analyzed, and diagnosed method on the pre-ignition was investigated. The experiment results showed that the time and the severe degree of pre-ignition under different pressure rise rate could be diagnosed by using the wavelet analysis method. Based on the experiment it is found that the most important factors effecting pressure rise rate of hydrogen fueled engines are spark advance and excess air ratio. Finally, the formulae between the pressure rise rate of the engine and spark advance, and between the pressure rise rate of the engine and excess air ratio, were respectively established by data fitting, so that control law about the pressure rise rate of the engine was also formed. This can provide a mensurable method for restraining the abnormal combustion of the engine.
The performance characteristics of a rice husk based integrated gasification combined cycle (IGCC) plant has been developed at the variable operating conditions of gasifier. A thermo-chemical model developed by the authors has been applied for wet fuel (fuel with moisture) for predicting the gas composition, gas generation per kg of fuel, plant efficiency and power generation capacity, and NOx and CO2 emissions. The effect of the relative air fuel ratio (RAFR), steam fuel ratio (SFR), and gasifier pressure has been examined on the plant electrical efficiency, power output, and NOx and CO2 emissions of the plant with and without supplementary firing (SF) between gas turbine (GT) outlet and heat recovery steam generator (HRSG). The optimum working conditions for efficient running of the IGCC plant are 0.25 RAFR, 0.5 SFR, and 11 bar gasifier pressure at the GT inlet temperature of 1200 degrees C. The optimum operational conditions of the gasifier for maximum efficiency condition are different compared to maximum power condition. The current IGCC plant results 264.5 MW of electric power with the compressor air flow rate of 375 kg/s at the existed conventional combined cycle plant conditions (Srinivas et al., 2011, "Parametric Simulation of Combined Cycle Power Plant: A Case Study," Int. J. Thermodyn. 14(1), pp. 29-36). The optimum compressor pressure ratio increases with increase in GT inlet temperature and decreases with addition of SF. [DOI: 10.1115/1.4006042]
Dimethyl Ether (DME) is an alternative liquid fuel developed mainly from coal and natural gas that can be used in compression ignition (CI) engines without major modifications to the diesel configuration. One of the advantages of DME combustion is the low emission levels of nitrous oxides (NOx) and particulate matter (PM) when compared to diesel combustion. Research so far were largely focused on tackling issues due to less viscosity and low heating capacity of DME as compared to diesel and in developing DME specific fuel system to overcome its incompatibility with rubber seals. In this paper, the body of experimental and numerical research on gaseous and PM emissions from DME combustion is reviewed, with the objective being to identify promising methods for emission control in DME engines. Gaseous emissions from DME combustion is a well-researched topic, while PM emissions has not yet been explored in detail. PM emissions, especially ultra-fine particulate matter (UFPM), are expected to become a major concern with the implementation of future emission norms. This review paper critically evaluates some of the novel methods of emission control in CI engines to meet future emission regulations using fuel injection strategies, combustion after-treatment and suggests future direction for DME research.
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), NOx 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 NOx 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.
In this paper, we analyze the feasibility of using urea for onboard hydrogen production to improve the efficiency of vehicles. Here, hydrogen is used as an additive to the primary fuel (gasoline, diesel). Urea is generally obtained in large quantities by combining ammonia with carbon dioxide in industry. The reverse reaction of decomposing urea into ammonia and carbon dioxide is widely known and currently used for production of ammonia in diesel vehicles where it serves as a NOx reduction agent. In the present system, the vehicle is equipped with a tubular urea tank as placed in the vicinity of the exhaust pipes. The heat recovered from the exhaust gases is used for catalytic conversion of urea into ammonia. The resultant ammonia is further flown over a catalytic membrane where hydrogen is separated from nitrogen. The highly pure hydrogen is then mixed with the fuel and combusted in the engine. We also study how engine efficiency, specific shaft work, specific fuel consumption and costs are affected by this process.
A 1.9 liter Volkswagen TDI engine has been modified to accomodate the addition of hydrogen into the intake manifold via timed port fuel injection. Engine out particulate matter and the emissions of oxides of nitrogen were investigated. Two fuels,low sulfur diesel fuel (BP50) and soy methyl ester (SME) biodiesel (B99), were tested with supplemental hydrogen fueling. Three test conditions were selected to represent a range of engine operating modes. The tests were executed at 20, 40, and 60 % rated load with a constant engine speed o 1700 RPM. At each test condition the percentage of power from hydrogen energy was varied from 0 to 40 %. This corresponds to hydrogen flow rates ranging from 7 to 85 liters per minute. Particulate matter (PM) emissions were measured using a scaning mobility particle sizer (SMPS) and a two stage micro dilution system. Oxides of nitrogen were also monitored. For most conditions of both diesel and biodiesel testing a reduction in total mass and umber PM emissions is observed with increasing amounts of hydrogen energy input. A small reduction of NO x emissions is observed with 5% hydrogen energy input at all load conditions. At all other conditions NOx emissions show little change with hydrogen energy input. At all conditions tested there is a significant increase in the ratio of NO2 to NOx in the engine out emissions with increasing amounts of hydrogen. The most notable changes occur with less than 10% hydrogen energy added. This phenomenon is seen with both diesel and biodiesel.
The requirement to significantly reduce NOxNOx and particulate matter (PM) emissions while maintaining efficient combustion performance is one of the main drivers for internal combustion engine research. Modern diesel and premixed charge compression ignition (PCCI) engines have improved engine fuel economy and significantly reduced NOxNOx and PM emissions achieved by advances in both combustion and exhaust aftertreatment technologies.To date, it has been shown that vehicle emissions can be further improved by several catalytic systems including fuel reformers (i.e. partial oxidation, autothermal, and exhaust gas reforming) and aftertreatment systems, such as the selective catalytic reduction (SCR) of NOxNOx under oxygen-rich conditions. Among the most promising on-board reforming technologies is the exhaust-gas reforming, which allows the fuel/air feed to the engine to be enriched with reformate containing H2H2 and CO. This method is a combination of reforming and exhaust-gas recirculation (EGR) and referred to as REGR.This paper reports on experimental results obtained when 1%Pt/Al2O31%Pt/Al2O3 low temperature hydrocarbon-SCR catalyst was used to treat exhaust gas from a diesel engine operating with addition of simulated REGR (two different compositions). It has been shown that while REGR can directly improve engine performance and emissions by promoting the PCCI combustion mode, it can also benefit the performance of the SCR catalysts due to the presence of unburnt H2H2 in the exhaust gas.
To achieve high power and high efficiency in a hydrogen fueled engine for all load conditions, the dual injection hydrogen fueled engine that can derive the advantage of both high efficiency from external mixture hydrogen engine and high power from direct cylinder injection hydrogen engine was introduced. For verifying the feasibility of the above engine, the high pressure hydrogen injector of ball valve type actuated by a solenoid was developed. A systematic experimental study was conducted by using a modified single cylinder dual injection hydrogen fueled engine which was equipped with both an intake injector and a high pressure in-cylinder injector. The results showed that (1) the developed high pressure hydrogen injector with a solenoid actuator had good gas-tightness and fine control performance, (2) the transient injection region, in which injection methods are changed from external fuel injection to direct-cylinder injection, ranged from 59 to 74 percent of the load, and (3) the dual injection hydrogen fueled engine had the maximum torque of direct-cylinder fuel injection and the maximum efficiency of external fuel mixture hydrogen engines.
To understand the occurrence of backfire in hydrogen fueled engines using art external (inducted) fuel supply, a fundamental study was completed using a modified experimental engine. A relation was found between the crevice volume in the combustion chamber and the occurrence of backfire. The results showed that the crevice around the spark plug electrode was not a major cause of backfire, but the combustion state of the mixture in the piston top land crevice, second land, and ring groove did have a direct affect on backfire occurrence. By increasing the top land crevice volume and the amount of flow-by gas, the equivalence ratio before backfire occurred was extended.
A hydrocarbon-selective catalytic reduction (HC-SCR) silver–alumina monolith catalyst has been prepared and tested for NOx emissions control in a diesel engine. The work is based on ongoing laboratory experiments, catalyst research, and process development. Hydrogen and actual reformate (i.e. H2 and hydrocarbon species produced in a partial and exhaust gas fuel reformer) significantly improved the passive control (i.e. no externally added hydrocarbons) NOx reduction activity over the SCR catalyst using the whole engine exhaust gas from a single-cylinder diesel engine. Optimisation of the reforming process is required for various engine conditions in order to maximise H2 production and minimise fuel penalty. When diesel fuel partial oxidation and exhaust gas reforming for SCR were implemented, the calculated fuel penalty was in the range of 5–10%, which is relatively high, as both reformers were not optimised yet. During HC-SCR of NOx over silver–alumina, the known promoting effect of H2 has been found to be sensitive to various factors, especially the engine exhaust gas temperature, H2 concentration, HC concentration, HC:NOx ratio, and space velocity. Under active control (i.e. hydrocarbon injection) SCR operation, powdered Ag–Al2O3 catalysts gave significantly higher initial NOx reduction, but the catalyst activity deteriorated rapidly with time due to poisoning species adsorption (e.g. HCs, nitrates, particulate matter (PM), etc.), whilst for the Ag–Al2O3-coated monolithic catalysts, NOx reduction activity was lower but remained constant for the duration of the tests. The improved physical (mass transfer, filtering of C-containing species) and chemical (reaction kinetics) processes during HC-SCR over powders compared to monoliths led to better initial catalyst activity, but it also accelerated catalyst deactivation which led to increased diffusion limitations.
In the presented work the selective catalytic reduction (SCR) of NOx in a real diesel engine exhaust gas (O2 present) from the engine operating at different conditions with and without H2 and CO additions were studied. The tests were carried out using real diesel engine exhaust gas over 1%Pt supported on alumina (Al2O3). The catalyst exhibits good NOx reduction activity at a narrow temperature range of 200 to 300∘C when there is only a HC present. The maximum NOx reduction of around 60% was achieved at temperature of 260∘C. Although, the engine operating with EGR improves the percentage of NOx converted in the SCR system due to increased HC:NOx ratio and reduced NOx concentration in the engine exhaust gas, the number of NOx-ppm reduced over the catalyst was reduced. The cause of this effect is not yet clear, but there are evidences that this attributes to (a) lower NOx coverage on the catalyst surface, which in turn makes its reduction by HC less probable and (b) the increased soot emissions which are blocking part of the catalyst active sites that are active in reducing NOx. Hydrogen addition expands the SCR activity window towards lower temperatures (100–300∘C) without affecting the maximum NOx conversion. In contradiction to H2 the CO addition is favourable to the H2 oxidation reaction and the poisoning of the catalysts active sites and the good low temperature NOx reduction activity cannot be seen. The incorporation of a mini-exhaust gas-reformer on-board a vehicle to provide the H2 in the SCR reactor will require catalyst design and reactor engineering to maximise H2 production and eliminate CO with the minimum penalty in the fuel economy.
Both intake port injection type and in-cylinder injection type hydrogen fuel supply systems are designed for a single-cylinder research engine to investigate the effect of mixture formation on the performance of the hydrogen-fuelled engines. The intake port injection is superior in thermal efficiency and engine operation stability at low load conditions. However, the in-cylinder injection is superior for high load condition. In an engine experiment with throttling condition, the engine with intake port injection operates more stably and efficiently when fuel–air equivalence ratio is maintained above a certain level despite the pumping loss due to stable combustion. Thus, the hydrogen-fuelled engines can be operated more stably with the in-cylinder injection at high load and more efficiently with the intake port injection at low load. Therefore, the optimised operation of the hydrogen-fuelled engines can be achieved with a dual injection system and throttle valve control.
In this investigation, an attempt was made to burn hydrogen in compression ignition engines that were operated on a dual fuel principle. Hydrogen was supplied along with intake air in small proportions and ignition was initiated by injecting diesel fuel in the conventional manner. A single cylinder compression ignition engine was operated throughout its load range inducting small proportions of hydrogen in intake air. Such an operation resulted in an increase of thermal efficiency at full load, a reduction in exhaust temperature and an increase in maximum pressure. Nitrogen oxides in the exhaust were observed to increase though the hydrocarbon emissions reduced as expected. Closed vessel explosions were conducted to study the effect of adding a hydrocarbon to a hydrogen-air mixture on the flame propagation velocities. The effect of increasing the proportion of hydrogen in the hydrogen-hydrocarbon-air mixture was observed to increase the flame propagation velocity.
The charged hydrogen engine with internal mixture formation as part of the HYPASSE (Hydrogen Powered Automobiles using Seasonal and weekly Surplus of Electricity) project will be presented. With direct hydrogen injection it is possible to solve the problems of hydrogen engines with external mixture formation. Those problems are knocking, glow ignition during compression stroke and backfiring past the intake valve. With the internal mixture formation system, the volumetric efficiency and the power output is equal to that of a diesel engine. To obtain low NOx emissions it is necessary to operate the H2-engine at excess air ratios λ ⩾ 2 by means of turbocharging. The discrepancy between late high-pressure injection together with diffusion flame propagation and early injection, i.e. to obtain a more homogeneous internal mixture formation, is studied by operating a single-cylinder research engine.
An ultra-low sulphur diesel (ULSD) fuel and a synthetic gas-to-liquid (GTL) fuel, besides different types of standard and reformed EGR, were evaluated in a single-cylinder, direct injection, diesel engine equipped with hydrocarbon-selective catalytic reduction (HC-SCR) aftertreatment system. The results obtained were statistically analysed (at 95% statistical significance) to identify the most significant factors that affect NOx emissions and to search for the optimum operation conditions in order to minimize these emissions. For that purpose, a fully crossed factorial experimental design was used, including two different engine speeds (1200 and 1500 rpm), two engine loads (25% and 50%), and four EGR/REGR ratios (0%, 10%, 20% and 30%) resulting in almost one hundred tests. An optimal combination of fuel type, REGR type and REGR ratio was proved to reduce around 89–95% of the reference NOx emissions. In general, at 25% engine load GTL fuelling combined with the reformed EGR with the highest hydrogen content was found the most desirable, as the hydrogen sharply increased the NOx conversion in the SCR catalyst. Differently, at 50% load standard EGR was sufficient to reach high NOx reductions. These findings may be used for the implementation of a system on-board capable to switch from EGR to REGR, which will help engine manufacturers to meet the future emission regulations.
A review is given of contemporary research on the hydrogen-fueled internal combustion engine. The emphasis is on light- to medium-duty engine research. We first describe hydrogen-engine fundamentals by examining the engine-specific properties of hydrogen and surveying the existing literature. Here it will be shown that, due to low volumetric efficiencies and frequent preignition combustion events, the power densities of premixed or port-fuel-injected hydrogen engines are diminished relative to gasoline-fueled engines. Significant progress has been made in the development of advanced hydrogen engines with improved power densities. We discuss several examples and their salient features. Finally, we consider the overall progress made and provide suggestions for future work.
In order to investigate the effect of hydrogen on the thermal stability of the amorphous ZrxNi1−x alloys, the crystallization of the hydrogenated alloys is examined using differential scanning calorimetry. By hydrogenation, the crystallization reaction is accelerated and the cubic ZrH2 phase is formed at first. At the next step, cubic ZrH2 is further transformed to the tetragonal structure. The corresponding mechanism is different from that of the as-received state and it is proposed to be related to the motion of nickel atoms, these having smaller atomic radius. When partially substituting titanium, the crystallization temperature and activation energy are greatly increased for both the as-received and the hydrogenated systems. This is thought to be caused by the retardation of the nickel diffusion and by hardening of the amorphous structure elastically, due to the presence of titanium atoms.
It is practically impossible to replace the internal combustion engines which have already become an indispensable and integral part of our present day life style, particularly in the transportation and agricultural sectors. Unfortunately, the survival of these engines has, of late, been threatened by the dual problems of the fuel crisis and environmental pollution. Therefore, to sustain the present growth rate of civilization, a non-depletable, clean fuel must be expeditiously sought. Hydrogen exactly caters to these specified needs. Hydrogen, even though “renewable” and “clean-burning” it does give rise to some undesirable combustion problems in an engine operation, such as backfire, pre-ignition, knocking and rapid rate of pressure rise. It has been experimentally evaluated that the fuel induction technique (FIT) does play a very dominant role in obtaining smooth engine operation. This paper discusses such various possible modes. Research work carried out by different investigators has been highlighted.
The autoignition and combustion of hydrogen were investigated in a constant-volume combustion vessel under simulated direct-injection (DI) diesel engine conditions. The parameters varied in the investigation included: the injection pressure and temperature, the orifice diameter, and the ambient gas pressure, temperature and composition. The results show that the ignition delay of hydrogen under DI diesel conditions has a strong, Arrhenius dependence on temperature; however, the dependence on the other parameters examined is small. For gas densities typical of top-dead-center (TDC) in diesel engines, ignition delays of less than 1.0 ms were obtained for gas temperatures greater than 1120 K with oxygen concentrations as low as 5% (by volume). These data confirm that compression ignition of hydrogen is possible in a diesel engine at reasonable TDC conditions. In addition, the results show that DI hydrogen combustion rates are insensitive to reduced oxygen concentrations. The insensitivity of ignition delay and combustion rate to reduced oxygen concentration is significant because it offers the potential for a dramatic reduction in the emission of nitric oxides from a compression-ignited DI hydrogen engine through use of exhaust-gas-recirculation.
This paper describes the experimental results on a hydrogen fueled single cylinder engine to study the characteristics of a solenoid-driven intake port injection type hydrogen injection valve. In experiments, the fuel-air equivalence ratio was varied from the lean limit at which stable operation was guaranteed to the rich limit at which flash-back occurred and spark timing was also changed. As a consequence, a hydrogen intake port injection system can be easily installed on a spark ignition engine only with simple modification and the flow rate of hydrogen supplied can also be controlled conveniently. In this case, the most serious problem is flash-back and it can be suppressed by accurate control of injection timing and elimination of hot spots on the surface of the combustion chamber.
A long-term hydrogen-based scenario of the global energy system is described in qualitative and quantitative terms here, illustrating the key role of hydrogen in a long-term transition toward a clean and sustainable energy future. In an affluent, low-population-growth, equity and sustainability-oriented B1-H2 world, hydrogen technologies experience substantial but plausible performance and costs improvements and are able to diffuse extensively. Corresponding production and distribution infrastructures emerge. The global hydrogen production system, initially fossil based, progressively shifts toward renewable sources. Fuel cells and other hydrogen-using technologies play a major role in a substantial transformation toward a more flexible, less vulnerable, distributed energy system which meets energy needs in a cleaner, more efficient and cost-effective way. This profound structural transformation of the global energy system brings substantial improvements in energy intensity and security of supply and results in an accelerated decarbonization of the energy mix, with subsequent relatively low climate impacts. Such energy-system path might still not be sufficient to protect against the risk of high climate sensitivities, but hydrogen-based technologies emerge as flexible options for the energy system and, thus, would be prime candidates for a risk management strategy against an uncertain climate future.
Active research in the development of hydrogen-fuelled low-emission engines is being pursued at the Engines and Unconventional Fuels Laboratory of the Indian Institute of Technology (IIT), for a period of close to two decades. This paper highlights the significant pursuits and attainments of the research and development (R&D) activities carried out in IIT, Delhi on hydrogen-operated engines. Both spark ignition (SI) and compression ignition engine test rigs have been developed and instrumented for the use of hydrogen fuel. Several existing petroleum-fuelled engine configurations have been modified by taking care to observe that the converted system does not need substantial hardware modifications. Various fuel induction techniques have been experimentally evaluated keeping in view the temperamental combustion characteristic of this fuel. Curative and preventive steps have been adopted and suitable retrofits and subsystems have been installed at the appropriate locations to preclude the possibility of any undesirable combustion phenomena such as backfire, knocking and rapid rate of pressure rise. Performance, emission and combustion characteristics of the systems have been determined. It has been observed that an appropriately designed timed manifold injection system can overcome the problem of backfire in a hydrogen engine. NOx emission level from a hydrogen-operated SI engine can be drastically reduced by way of lean engine operation.
Hydrogen is a versatile fuel with the unique potential of providing an ultimate freedom from an energy (fuel) crisis and environmental degradation. This paper describes some aspects of a series of experimental studies carried out in several configurations of hydrogen-operated engine, keeping in view the possibility of introducing hydrogen engine into the existing energy infrastructure. Optimum performance and low-emission characteristics have been experimentally identified and steps have been identified to get rid of undesirable combustion phenomena such as backfire, pre-ignition, knocking and rapid rate of pressure rise.As far as the introduction of hydrogen engine into the transportation sector is concerned, fuel-induction technique forms the most important aspect of development. Our studies show that timed manifold injection (TMI) has the potential of being the most appropriate fuelling strategy. A TMI-operated engine does not need any substantial modification in the existing system hardware and ensures high thermal efficiency and low specific fuel consumption without any symptoms of undesirable combustion. Experimental investigations carried out with a typical multi-cylinder automotive engine adopting exhaust gas recirculation (EGR) indicate that the NOx emission level can be drastically reduced over a wide range of operating conditions.Considering the prospects of introducing hydrogen engine into the agricultural sector or a decentralized energy units, this paper also deals with the performance improvement achieved by way of hydrogen substitution in a small horsepower diesel engine widely adopted in rural/agricultural sector of developing countries. It has been experimentally observed that the range of smooth engine operation can be increased and the level of energy contribution in such systems can be substantially enhanced by adopting a charge dilution technique.
The deteriorating quality of air due to exhaust emissions and the increasing number of motor vehicles in the world, is sending alarming waves throughout the world to try to do something to cut off or significantly reduce these emissions in order to save our planet. Scientists have found that hydrogen presents the best and unprecedented solution to this problem, for its superior combustion qualities and availability. This paper discusses analytically one aspect of combustion i.e. combustion duration and how it is affected by an engine’s operating parameters like compression ratio, equivalence ratio, spark plug location, spark timing and engine speed, and how it affects an engine’s performance parameters like brake specific fuel consumption, brake mean effective pressure, thermal efficiency, as well as emission characteristics.
Development of urea-SCR system for lightduty diesel passenger car
- Sung
- Choi
- Yung
- Yoon
- Seok
- Kim
- Gwon
- Yeo
- Hyun
- Han
Sung-mu Choi, Yung-kee Yoon, Seok-jae Kim, Gwon-koo Yeo, Hyun-sik Han. Development of urea-SCR system for lightduty diesel passenger car. SAE Transaction 2001-01-0519.
Crystallization behaviors of the hydrogenated Zr-rich amorphous Zr x Ni 1Àx : H alloys and the effects of titanium substitution i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 4 ( 2 0 0 9
- Th Jang
- Yg Kim
- Lee
Jang TH, Kim YG, Lee JY. Crystallization behaviors of the hydrogenated Zr-rich amorphous Zr x Ni 1Àx : H alloys and the effects of titanium substitution. International Journal of Hydrogen Energy 1992;17:951–4. i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 4 ( 2 0 0 9 ) 9 0 1 9 – 9 0 3 2 9032
Properties of hydrogen, Summer school of Hydrogen Energy conducted in IIT Madras
- B Nagalingam
Nagalingam B. Properties of hydrogen, Summer school of
Hydrogen Energy conducted in IIT Madras; 1984.