Increase In Nitrogen Oxides Research Articles

Investigation of bioethanol production from jatropha deoiled cake and its blending effects for environmental sustainability.

This paper describes the process of extracting ethanol from Jatropha curcas and its various blending effects on spark-ignited engine performance for environmental sustainability. Alternatives to conventional fuel sources have to be found because of the depletion of fossil fuels and stringent regulations. Every day, the growing population and improved transportation increase the energy demand. Bioethanol is an effective substitute for gasoline and SI engine diesel. Worldwide, passenger cars typically blend 10% bioethanol with gasoline. Some nations, like India, have stated plans to blend 20% bioethanol with gasoline starting shortly. From leftover jatropha deoiled cake (JDC), bioethanol was produced utilizing the fermentation and vacuum distillation methods. Four different blends were prepared on a volumetric basis at different engine speeds at a constant compression ratio of 10:1 and the wide-open throttle was tested for various performances and emissions. Bioethanol enrichments reduce CO and CO2 emissions but increase nitrogen oxide emissions. JDCE 15 was found to have the best engine performance out of all the fuel blends tested. This study suggests that, if NOx emission reduction measures are carried out, JDC can be used as a source for the manufacturing of second-generation bioethanol.

Increase in daily asthma medication sales in association with air pollution levels in Greater Stockholm.

We conducted a time-series study with data on asthma medication purchases and daily mean values of particulate matter ≤10 µm (PM10), nitrogen oxides (NOx), and ozone during 2018-2019. We used nonlinear distributed lag quasi-Poisson regression models to estimate the associations between air pollution levels and medication purchases, adjusting for meteorological variables, pollen levels, day of the week, and long-term trends. The models established linear relationships between air pollutants and the outcome, and potential delayed effects were smoothed with a spline across a lag period of 2 weeks. We applied separate models for each municipality (n = 21) in Greater Stockholm, and calculated pooled estimates to achieve combined results for the whole region. We observed associations between daily levels of air pollution and purchases of asthma medications, most clearly for PM10. The pooled estimates of the relative risks for asthma medication purchases across all 21 municipalities associated with a 10 μg m-3 increase in PM10 the same day (lag 0) was 1.7% [95% confidence interval (CI): 1.2%, 2.1%], a cumulative increase of 4.6% (95% CI: 3.7%, 5.6%) over one week (lag 0-6), and a 6.5% (95% CI: 5%, 8%) increase over 2 weeks (lag 0-13). The corresponding pooled effect per 10 μg m-3 increase in NOx and ozone were 2.8% (95% CI: 1.6%, 4.1%) and 0.7% (95% CI: 0%, 1.4%) over 2 weeks (lag 0-13), respectively. Our study revealed short-term associations between air pollution, especially PM10, and purchases of asthma medications.

Combustion and Emission of Castor Biofuel Blends in a Single-Cylinder Diesel Engine

Fossil fuels confront the problem of strategic resource depletion since they have been continuously utilized for more than 200 years and cause serious damages to the ecological environment of the planet. In this work, the transesterification of castor plant oil was utilized to make biodiesel, and castor biodiesel’s physicochemical qualities were assessed. On a single-cylinder, four-stroke, water-cooled agricultural diesel engine, an experimental study was conducted to compare and analyze the engine performance and emission characteristics of diesel and biodiesel blends in various amounts. The B20, B40, B60, and B80 biodiesel blends were evaluated at different engine speeds (1200, 1400, 1600, and 1800 rpm) with a constant engine load (50%). According to the experimental findings, the brake thermal efficiency (BTE) declines as the engine speed rises, and the biodiesel fuel blend has a lower brake thermal efficiency (BTE) than diesel fuel because of its higher density and viscosity and lower calorific value. The amount of gasoline required to create power increases as the speed does, and the brake-specific fuel consumption (BSFC) trend is upward. Due to their low calorific value and high viscosity properties, biodiesel blends have a greater brake-specific fuel consumption (BSFC) than diesel. The fuel’s exhaust gas temperature (EGT) has an upward trend with an increased rotational speed. The biodiesel blend’s high cetane number shortens the ignition delay and lowers the exhaust gas temperature (EGT) compared to diesel. A fuel with oxygen added, biodiesel enhances combustion, increases the combustion temperature, speeds up the oxidation process, and lowers carbon monoxide (CO) and hydrocarbon emissions. B80 produces the lowest carbon monoxide and hydrocarbon emissions at 1800 rpm, at 0.33%, and 30 ppm, respectively. On the other hand, increased carbon dioxide (CO2) emissions result from a high oxygen concentration. In addition, compared to diesel fuel, biodiesel’s greater combustion temperature causes the creation of increased nitrogen oxide (NOx) emissions. According to the research findings, a castor biodiesel fuel blend is an excellent alternative fuel for engines since it can be utilized directly without modifying the current engine construction and has good engine and exhaust emission performance.

Evaluation of CI Engine Performance, Emissions, and Combustion Characteristics Using Corn Biofuel Blend with Divergent Cr's and Exhaust Gas Recirculation

This thesis investigates the potential of corn oil biodiesel as a renewable alternative fuel for diesel engines. An experimental study is conducted to enhance the engine characteristics of corn oil blended diesel through various approaches, including adjusting the compression ratio, employing different exhaust gas recirculation (EGR) rates, and incorporating Nano additives into the fuel. Preliminary examinations of corn oil methyl ester (COME) blends at 10%, 20%, and 30% reveal that the COME20 blend outperforms the others, establishing it as the preferred blend for further investigation. Subsequently, the investigation proceeds with COME20 at different load and speed conditions. The experimental results demonstrate notable improvements in engine performance. Specifically, at a compression ratio of 20:1 (CR20:1) compared to 18:1 (CR18:1), brake thermal efficiency increases by 2.72%, and brake-specific fuel consumption (BSFC) decreases by 7.8%. Furthermore, significant reductions in exhaust emissions, including carbon monoxide (17.64%), unburnt hydrocarbons (13.8%), and smoke opacity (3.5%), are observed. However, there is an increase in nitrogen oxides (NOx) emissions. In terms of exhaust gas recirculation (EGR), the addition of 6% and 12% EGR to COME20-CR20 results in reduced NOx emissions compared to diesel. Notably, the 12% EGR exhibits a greater reduction in NOx emissions but compromises engine performance to a greater extent than the 6% EGR. In conclusion, this study highlights the potential of optimizing engine design (compression ratio), control (EGR rate), and fuel reformulation (COME biodiesel blending) to facilitate the efficient utilization of COME biodiesel blended diesel fuel in compression ignition (CI) engines. The findings contribute to the advancement of renewable fuel technologies and offer insights for future developments in the field of sustainable transportation. KEYWORDS: Corn oil biodiesel, Renewable alternative fuel, BSFC (Brake-specific fuel consumption), Compression ratio, Exhaust gas recirculation (EGR), Nano additives, COME20 blend

Engine performance and emissions evaluation of surfactant-free B30 biodiesel–diesel/water emulsion as alternative fuel

Malaysia is one of the top exporters of palm oil, and although currently facing fierce resistance towards palm oil imports in some parts of the globe, one of the ways to utilize this commodity is by increasing palm biodiesel content in local commercial diesel. However, due to the oxygen-rich nature of biodiesel, its utilization suffers from increased nitrogen oxides (NOx) emission compared to conventional diesel. To mitigate this issue and improve diesel engine performance and emissions using biodiesel–diesel blends, this study attempted to investigate implementation of a real-time non-surfactant emulsion fuel supply system (RTES) which produces water-in-diesel emulsion as fuel without surfactants. NOx reducing capability of water-in-diesel produced by RTES has been well documented. Therefore, in this study, 30% biodiesel–diesel (B30) was used as the base fuel while B30-derived emulsions consisting of 10 wt%, 15 wt% and 20 wt% water content were supplied into a 100 kVA, 5.9-L common rail turbocharged diesel engine electric generator. Fuel consumption and exhaust emissions were measured and compared with commercially available Malaysian low grade diesel fuel (D2M). Evidence suggested that emulsified B30 biodiesel–diesel produced by RTES was able to increase brake thermal efficiency (BTE) up to a maximum of 36% and reduce brake specific fuel consumption (BSFC) up to 8.70%. Furthermore, B30 biodiesel–diesel emulsions produced significantly less NOx, carbon monoxide and smoke at high engine load. In conclusion, B30 biodiesel–diesel emulsions can be readily utilized in current diesel engines without compromising on performance and emissions.

Can We Find an Optimal Fatty Acid Composition of Biodiesel in Order to Improve Oxidation Stability?

Air quality currently poses a major risk for human health. Currently, diesel is widely used as fuel and is a significant source of nitrogen oxides (NOx) and particulate matter (PM), both hazardous to human health. A good alternative for mineral diesel is biodiesel, not only for the improvement of hazardous components in the exhaust gases but also because it can be produced in view of a circular economy. Biodiesel consists of a mix of different fatty acid methyl esters, which can react with oxygen. As a consequence, the oxidation stability of biodiesel has to be studied, because the oxidation of biodiesel could affect the performance of the engine due to the wear of injectors and fuel pumps. The oxidation stability could also affect the quality of the exhaust gases due to increases in NOx and PM. The basic question we try to answer in this communication is: ‘Can we find an optimal fatty acid composition in order to have a maximal oxidation stability?’ In this article, we try to find the optimal fatty acid composition according to the five most common fatty acid methyl esters present in biodiesel in order to reach a maximal oxidation stability. The measurements and statistical analysis show, however, that there is no useful regression model because there are statistically significant two- and three-way interactions among the different fatty acids.

The impacts of nano fuels containing Fe-Ni-TiO2/activated carbon nanoparticles on diesel engine performance and emission characteristics

. Biofuels, which are widely used as alternative fuels to reduce fossil fuel consumption and replace them with fossil fuel-like energy sources, are increasingly being supplemented with nanoparticles (NP) to overcome their limitations, including lower energy content and higher emissions. The study aimed to examine the impact of Fe-Ni-TiO2/activated carbon (AC) nanoparticles, produced by the authors, on engine performance and emissions when added to diesel/biodiesel fuel blends. The produced Fe-Ni-TiO2/AC NP was employed as an additive in palm oil (PO)/diesel fuel blends at 50 and 100 ppm concentrations. The results revealed that compared to standard diesel, employing Fe-Ni-TiO2/AC NPs lowered emissions including smoke, carbon monoxide (CO), and hydrocarbon (HC) in all fuel blends while increasing nitrogen oxide (NOx). In the DNP30-100 fuel blend at 2500 W engine load, there was an increase in NOx by 8% and a decrease in CO, HC, and smoke emissions by 70.3%, 86.3%, and 57.5%, respectively, compared to standard diesel. Furthermore, a decrease of 11.38% was observed in brake-specific fuel consumption, while brake thermal efficiency increased by 16.59% compared to diesel. The overall results suggest that using Fe-Ni-TiO2/AC as an additive in a diesel–biodiesel fuel blend can improve engine performance and decrease emissions.

Experimental investigation of gasoline ethanol methanol iso-stoichiometric blends on SI engine

The current work presents the formulation and experimental investigation of E20 (Ethanol 20%, Gasoline 80% (v/v)) and its equivalent iso-stoichiometric GEM (Gasoline, Ethanol and Methanol) blends on performance and emission features of a single cylinder, four stroke SI engine. Experiments were carried out at constant engine load and at different engine speeds. The formulated blends were termed as binary blend E20 (G 80 E 20) and its equivalent GEM blends, E20_B1 (G 83 E 10 M 7), E20_B2 (G 85 E 5 M 10) and E20_B3 (G 87 E 0 M 13) respectively. The formulated E20 equivalent GEM blends have similar stoichiometric Air-Fuel ratio, Lower heating value and Octane number as binary E20 blend. The engine performance, emission values of blended fuels were measured and compared with pure gasoline, G. The results showed that the E20 equivalent GEM blends have similar brake thermal efficiency as the binary E20 blend and also improved compared to straight gasoline. And also exhaust emissions such as carbon monoxide (CO), unburned hydrocarbons (HC) show reduced values and increased nitrogen oxide (NOx) values for mixed fuels compared to pure gasoline.

Nanoparticles as Additive to the Diesel and Biodiesel along with Blends: A Review on Emission Characteristics and Performance of CI Engine

The depletion rate of fossil fuels are very high as well as they put negative impact on the environment. So the alternate fuels are required to meet the demand of the world. The bio based fuels and blends are the source which can be help for the sustainable development. The mild negatives of biodiesel, like its increased nitrogen oxide emissions, inconsistency with winter conditions, and frequent replacement cycles for engine parts like fuel filters, fuel tanks, and fuel lines owing to clogging, exceed its many advantages. By using nanoparticles as fuel additives, there is still room to improve the qualities of fuel and address its shortcomings. The role of nanoparticles additives increases the thermos-physical properties of the pure fuel, bio based fuel and blends. They directly affect how well the diesel engine performs. There are various nanoparticle additions that play diverse roles in the operation and emission process of the diesel engine. The common nanoparticles additives such as cerium oxide, aluminium oxide, magnesium, carbon nano tubes are the common additives which are directly used. This review article analyses the performance, emission traits, fuel characteristics, and issues with the nanoparticle additions. Additionally, this work aids researchers in their investigation of potential nanoparticle additions in the future.

Studies on the Performance of Engines Powered with Hydrogen-Enriched Biogas

Sustainability of energy supply has become a prime concern for energy producers and consumers alike. There is heightened awareness in the global community about the decreasing supply of conventional fossil fuels along with increasing fuel and energy demand and the consequent rise in unit energy cost. In addition to the sustainability aspect, the environmental impact of emissions from fossil fuel combustion is the focus of global targets for emissions reduction. In this context, the research and application of sustainable and non-polluting fuels become significant. Internal combustion (IC) engines are part of a significant energy-consuming sector, and the application of sustainable and non-polluting fuels within IC engines would be impactful. Biogas and hydrogen are viewed as sustainable and non-polluting alternatives to conventional fossil fuels. However, either of these used individually offer certain disadvantages. Experimental results and analysis of the performance and emissions characteristics of an IC engine fueled with biogas blended with 5, 10, and 15% hydrogen volume fractions are studied. An increase in hydrogen content increases the engine’s performance and power and reduces carbon monoxide (CO) and total hydrocarbons (THCs). However, nitrogen oxides (NOx) are found to increase due to higher combustion temperatures attributed to hydrogen. A 17.5% increase in brake power is observed for 15% hydrogen-enriched biogas, compared to plain biogas, at an equivalence ratio of 0.6. Similarly, a 17% increase in BTE, a 50% decrease in CO, a 68% decrease in UHC, but a 71% increase in NOx are observed for 15% hydrogen-enriched biogas.

Performance and emission characteristics of CI engine using hydrogen enrichment in biodiesel blend with additives—A review

It is an irresistible argument that there is a requirement for sustainable resources for energy production as there is an enormous rise in demand for energy. Various sectors involve a wide range of energy consumption shares. Conventional fuels are exhaustible and can be replaced with sustainable substitutes, i.e., biofuels including bio-ethanol, biogas, and biodiesel. Recently, biodiesel has gained popularity due to the availability and affordability of feedstock. To extract biodiesel from vegetable oils, the transesterification process is widely used. Biodiesel blends can be used as a direct substitute in diesel engines, which may result in a slight reduction in hydrocarbons, carbon monoxide, and an increase in oxides of nitrogen. The performance parameters may increase or decrease depending on the blend type and calorific value. The objective of this review is to analyze the performance and emission characteristics of second and third-generation biodiesel blends enriched with hydrogen and to explore techniques for improvement such as the addition of additives. Research has shown that the addition of hydrogen improves combustion, resulting in increased brake thermal efficiency and reduced brake specific fuel consumption. Similarly, the inclusion of additives can reduce the production of oxides of nitrogen during combustion. In conclusion, biodiesel blends enriched with hydrogen and additives can offer improved performance, combustion, and emission characteristics. To meet energy demand sustainably and reduce reliance on conventional fuels, further research is necessary to ensure the long-term viability of biodiesel as a sustainable energy source.

Investigation of ketal-acetin mixture synthesized from glycerol as a renewable additive for gasoline-ethanol fuel blend: Physicochemical characterization and engine combustion, performance, and emission assessment

Fossil fuel combustion in internal combustion engines, especially gasoline engines, leads to urban air pollution and contributes to greenhouse gas emissions and climate change. Ethanol has long been considered a promising option to replace gasoline and reduce the amount of associated pollution. Despite its advantages of improving fuel combustion and reducing pollutants, increasing nitrogen oxide emission is an environmental issue caused by using a high percentage of ethanol in fuel. Another challenge the biofuel industry faces is the crude glycerol produced as a by-product of the biodiesel production process, which requires a high-technology purification line, restricting biodiesel production capacity. Considering both challenges, the present study valorized glycerol into a fuel bio-additive, i.e., a ketal-acetin mixture, and developed gasoline-ethanol fuel formulations containing the synthesized bio-additive. To this end, the additive was synthesized through two-stage reactions, i.e., synthesizing acetin mixture using acetic acid and then ketalizing using acetone at specific reaction conditions. Afterward, different fuel samples were analyzed through a physicochemical study and tested in a spark-ignition engine setup. According to the results observed, adding a 2.5% ketal-acetin mixture to gasoline fuel containing 20% ethanol could improve brake power and thermal efficiency, especially at higher engine speeds. At higher engine speeds, there was a decrease in the brake specific fuel consumption values of the fuel sample containing a 2.5% ketal-acetin mixture. At the same time, besides maintaining the positive effects of ethanol presence in reducing engine exhaust emissions such as carbon monoxide and unburned hydrocarbons, this fuel blend reduced nitrogen oxides mean values by 34.5%.

A Hybrid Response Surface Methodology and Multi-Criteria Decision Making Model to Investigate the Performance and Emission Characteristics of a Diesel Engine Fueled With Phenolic Antioxidant Additive and Biodiesel Blends

AbstractOverconsumption of fossil fuels has accelerated global warming and raised environmental air pollution levels. Recent studies have looked into the potential use of alternative, environmentally friendly fuels for diesel engines in response to the rising need for oil. Biodiesel is a renewable alternative fuel that is environmentally friendly. The significant increase in nitrogen oxide (NOx) emissions is the most notable disadvantage of biodiesel. This study examined the effect of antioxidant-treated Jatropha biodiesel on the performance and exhaust emission parameters of a VCR diesel engine. For this study, diesel, Jatropha biodiesel (B30), and phenolic antioxidant additive diphenylamine at 100 ppm are added by weight to the B30 blend named as B30 + DPA fuel blend was used. A hybrid RSM was used in conjunction with CCD and MCDM approaches such as AHP and COPRAS techniques to produce a sustainable model to derive the most accurate optimum models for output responses. From experimental findings, the antioxidant significantly reduced NOx emission. The inclusion of DPA in the tested blend lowered the average NOx emissions and brake-specific fuel consumption (BSFC) by 7.4% and 7.8%, respectively as compared with B30. Also, the brake mean effective pressure (BMEP) of B30 + DPA is 5.01% and 0.38% higher than diesel and B30, maximum cylinder pressure (CPMax) is 0.9% higher than B30, but 3.4% lower than diesel. The optimal setting of engine input parameters is recorded at compression ratio of 15, 7.5% EGR-HOT, and 12 kg load, for optimum BP, BMEP, BSFC, CPMax, and NOx emissions. Therefore, the B30 + DPA blend is suitable for enhancing diesel engine performance and minimizing exhaust emissions.

Numerical simulation of a diesel engine performance powered by soybean biodiesel and diesel fuels

BackgroundThe present study presents a 3-D numerical simulation of a direct injection diesel engine powered by base diesel oil and soybean biodiesel fuel at different load conditions. The modeling was performed using commercial computational fluid dynamics (CFD) software linked to a chemical solver. A chemical kinetic reaction mechanism was developed to simulate the combustion and fuel spray processes. Base diesel oil results were verified using a single-cylinder, 4-stroke diesel engine.ResultsThe study showed that the usage of the soybean biodiesel fuel caused a reduction in carbon monoxide (CO) and hydrocarbon (HC) emissions by about 42.38% and 41.35%, compared with base diesel and an increase in nitrogen oxides (NOx) and carbon dioxide (CO2) emissions of about 21.8% and 11.2%, respectively. Exhaust gas temperature (EGT) is reduced by an average value of 9.4%, the brake-specific fuel consumption (BSFC) is increased by an average value of 11.8% and the brake thermal efficiency (BTE) is dropped by an average value of 11.3% for soybean biodiesel fuel.ConclusionsThe CFD model showed the effect of the unsaturated fatty acid methyl esters present in soybean biodiesel on the spatial distributed values of NOx, oxygen and temperature during the combustion in engine cylinder. It was observed that the combustion of soybean biodiesel began about 3.89 CAD earlier than base diesel, and the in-cylinder peak pressure was dropped by 8.25%. Soybean biodiesel fuel was optimized by performing four starts of injection (SOI) at timings of − 18, − 16, − 15 and − 13,5 bTDC, and it was found that the combustion characteristics of soybean biodiesel are optimum at SOI = − 15 bTDC. These results indicate that the biodiesel fuel can be used as an alternative and environmentally friendly fuel in the engine without any modifications.

Improving the energy and environmental performance of a diesel internal combustion engine by using a hydrogen-containing additive

BACKGROUND: The areas of hydrogen energetics development are analyzed. The main problems faced by Western automakers and which determine the ways to solve the problems of hydrogen vehicles are outlined. It is noted that small-scale production of hydrogen cars has already begun in Europe and the USA. The development of this direction requires the creation of a network of filling stations, which is related to the high financial cost of hydrogen fuel production technologies and the development of the appropriate infrastructure. The world economy transition to a new energy source requires the introduction of large electrical capacities.
 AIMS: Technologies of vehicle onboard hydrogen production with use of hydrogen-containing substances are of interest of the study, as they are highly safe, cheap in production and easy in service.
 METHODS: The experimental design developments on converting diesel and gasoline internal combustion engines to run on hydrogen, made by NAMI in the past years, are considered. In the development of this direction, MADI has developed an original method for vehicle onboard hydrogen production with hydrogen supply to the cylinders of a bifuel diesel internal combustion engine.
 RESULTS: During the tests, an increase in power indicators, an increase in the effective efficiency of the internal combustion engine and a decrease in the content of CH and CO in the exhaust gases of a diesel engine with a certain increase in nitrogen oxides were obtained.

Enhancement of the waste cooking oil biodiesel usability in the diesel engine by using n-decanol, nitrogen-doped, and amino-functionalized multi-walled carbon nanotube

The depletion of fossil fuels makes it necessary to find alternative fuels to diesel. Waste cooking oil biodiesel (WCO) has interesting properties and could replace diesel fuel. However, WCO biodiesel increased nitrogen oxides (NOx) at high loads compared to diesel. Thus, some fuel additives, such as functionalized MWCNTs and decanol, can be used as they are considered promising diesel fuel additives and significantly affect engine performance and exhaust emission levels. The functionalized MWCNTs, mainly Nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) and amino-functionalized multi-walled carbon nanotubes (NH2-MWCNTs), are excellent catalysts that have been used recently in many applications and have good properties that can be used in diesel engines. Thus, in the current research, an experimental investigation was performed by a CI engine working at a constant speed and different loads to study the effects of a WCO biodiesel-decanol blend on engine performance and exhaust gas emissions. First, n-Decanol was added to WCO biodiesel to enhance the biodiesel combustion properties (80 % biodiesel + 20 % n-decanol by volume). Then, two doses (50 and 75 ppm) for each type of functionalized MWCNTs were inserted into the WCO biodiesel-decanol blend to enhance the engine performance. The results illustrated that WCO biodiesel-decanol blend was close to diesel in engine performance, where the NOx and soot were reduced by about 8 % and 20 % for WCO biodiesel-decanol blends compared to diesel. Also, the addition of functionalized MWCNTs led to a significant reduction in the NOx, CO, and soot levels by around 35 %, 61 %, and 44 % compared to diesel. BTE was diminished by almost 10 %, and BSFC was raised by 15 % for WCO biodiesel-decanol blend compared to diesel. At the same time, these negative impacts have been alleviated with inserting functionalized MWCNTs into the WCO biodiesel-decanol combination. At 75 % load, WCO biodiesel-decanol blends raised the in-cylinder pressure and advanced the start of combustion by a three-crank angle degree. Therefore, it can be implied that WCODNH75 is a recommended combination considering combustion and emission characteristics.

Comparative analysis of the heat balance results of the selected Tier III-compliant gas-fuelled two-stroke main engines

Two-stroke engines are distinguished by the highest overall efficiency among all main engines. This is not only due to the low speed, and large piston stroke, but also to the high combustion temperature, which result in an increase in nitrogen oxides (NO<sub>x</sub>) emission. Technical solutions applied to bring main engines into compliance with current NO<sub>x</sub> emission standards set by the Tier III limits include the use of SCR and EGR systems, the implementation of the Otto cycle, and the application of liquified natural gas (LNG) as the low-emission fuel. Impact of the available Tier III-compliant technologies on the heat balance results is analysed using the example of the currently most popular dual-fuel main engines, i.e. WinGD X92DF and MAN G95ME-C10.5-GI. The possibilities of waste heat recovery in the electricity generation process and thereby improving the ship energy efficiency are discussed.

Investigation on combustion characteristics and gas emissions of a high-pressure direct-injection natural gas engine at different combustion modes

In the present study, the potential of natural gas pre-injection, mixing-limited combustion, and slightly premixed combustion modes were evaluated to achieve high thermal efficiency and low nitrogen oxides and carbon monoxide emissions. To this end, a dual direct injection model was established to perform numerical simulations. The obtained results revealed that in the natural gas pre-injection mode, the optimized natural gas pre-injection proportion and injection interval between the end of natural gas pre-injection and the start of diesel injection can significantly reduce carbon monoxide emissions and improve indicated thermal efficiency with a slight increase in nitrogen oxides. In the mixing-limited combustion mode, combustion phasing and indicated thermal efficiency are not sensitive to the variations of the injection interval between diesel and natural gas. Moreover, a larger injection interval between diesel and natural gas is beneficial to reduce carbon monoxide. In the slightly premixed combustion mode, as the injection interval between diesel and natural gas decreases, combustion phasing delays, carbon monoxide emissions reduce, and nitrogen oxides emissions increase first and then decrease. Advancing the start of natural gas injection increases maximum pressure rise rate and nitrogen oxides in both natural gas mixing-limited combustion and slightly premixed combustion modes but decreases carbon monoxide dramatically. The natural gas mixing-limited combustion mode has more potential to meet carbon monoxide limits imposed by the Euro VII standard with no need for extra after-treatment devices while improving thermal efficiency.

Response surface methodology-based optimization of the amount of cerium dioxide (CeO2) to increase the performance and reduce emissions of a diesel engine fueled by cerium dioxide/diesel blends

The supplement of metal nanoparticles to diesel fuel in specific amounts has been included as an innovative approach to the studies on reducing pollutant emissions of compression ignition engines. In present research, the impacts of adding cerium dioxide (CeO2) nanoparticles, which is a highly oxidizing and reactive additive, to diesel fuel in different amounts (25, 50, 75, and 100 ppm) were experimentally investigated at different engine loads (8, 12, 16, 20, and 25 Nm) and optimized using the response surface methodology (RSM). According to the experimental results, the supplement of CeO2 decreased the brake-specific fuel consumption (BSFC) and enhanced the brake-thermal efficiency (BTHE) and exhaust gas temperature (EGT). On the other hand, the addition of CeO2 caused a decrease in hydrocarbon (HC), carbon monoxide (CO), and smoke emissions, and on the contrary, an increase in nitrogen oxide (NOx) emissions. Under the RSM findings, determined the optimal CeO2 quantity and engine load as 100 ppm and 12 Nm, respectively. Optimum responses corresponding to optimal CeO2 and engine load were determined as 23.125%, 429.766 g/kWh, 335.143 °C, 0.257%, 130.898 ppm, 786.309 ppm, and 25.654% for BTHE, BSFC, EGT, CO, HC, NOx, and smoke, respectively. Optimal results were obtained with a high desirability value of 0.7115. A good agreement between the experimental and RSM-predicted response values indicates that the developed RSM design was successful.

Impact of additive ethylene glycol diacetate on diesel engine working with jatropha-karanja dual biodiesel

The present study investigates ethylene glycol diacetate as a prospective oxygenated additive for jatropha-karanja dual blended biodiesel for enhanced engine characteristics of a diesel engine. The experiments have been conducted at constant speed of 1500 rpm on a variable compression ratio diesel engine working with biodiesel having 10–30% of Jatropha and karanja oil methyl ester and 1–3% of additive. The brake thermal efficiency increased by 3.6–4.2% while the brake specific fuel consumption reduced by 0.08–0.24 kg/kWh for fuel blends by adding 3% additive. The hydrocarbon and carbon monoxide emissions reduced by a maximum of 7 ppm and 0.02% respectively with slight increase in nitrogen oxide over entire range of fuel blends. The peak cylinder pressure attained 53.2 bar with maximum heat release rate 63.7 J/oCA by addition of 3% additive. Thus, the ethylene glycol diacetate can be adopted as a suitable additive for jatropha-karanja blend dual biodiesel to achieve improved engine characteristics of diesel engines.