Search

The objective of this study is to develop a 1D CFD simulation model to identify the optimal design parameters, using GT-POWER prior to the optimization of a new rotary engine derived from a three-lobe gerotor pump (GP3 RTE) based on 3D CFD simulation. The models were compared based on their respective development stages (steps 1–4) to ascertain the impact of each parameter on performance. The step 4 model, which exhibited a similar trend to that observed in the 3D CFD results, was selected for further analysis and validation. The developed model accurately predicted GP3 RTE performance in terms of fuel consumption, indicated power, efficiency, and exhaust gas reticulation (EGR) behavior, approaching the accuracy of the CONVERGE model. Furthermore, the optimal intake/exhaust port locations and operating conditions of the GP3 RTE were derived using the developed step 4 model. The model provided a convenient and powerful tool for obtaining basic information regarding the unique behavior of the GP3 RTE, thereby enabling the optimization of the design parameters without the necessity for time-consuming three-dimensional design modifications. [ABSTRACT FROM AUTHOR]

Diesel generators are widely used to produce electricity and heat in remote communities. However, their use contributes to harmful pollutant and greenhouse gas (GHG) emissions, negatively impacting the environment and public health. Syngas, which is a sustainable fuel, can play an important role in the transition from petroleum to renewable fuels. When used in dual-fuel diesel engines, it can contribute to reducing GHG emissions and the cost of transporting diesel, especially for rural and remote communities. This study investigates the effects of optimizing the diesel direct injection (DI) and exhaust gas recirculation (EGR) strategies on the combustion and emission performance of a syngas-diesel dual-fuel generator at constant load. The experiments were conducted using a 30-kW generator with a four-stroke, four-cylinder, turbocharged, and electronically controlled direct-injection diesel engine. The intake manifold of the engine was modified to allow introducing syngas upstream of the turbocharger. The syngas was simulated using individually controlled flow rates of hydrogen (H 2), carbon monoxide (CO), carbon dioxide (CO 2), and nitrogen (N 2). The syngas flow rate was adjusted to replace 40% of the energy provided by diesel fuel while optimizing the diesel DI parameters such as the pilot injection timing, main injection timing and diesel direct injection rail pressure, as well as the EGR rate. The findings of this study reveal that optimizing diesel injection strategy and appropriately raising the EGR rate have a positive impact on the engine performance and emissions. • Optimizing diesel injection strategies and EGR rate of a syngas-diesel dual-fuel diesel engine. • Hydrogen-rich syngas enhances combustion efficiency and emissions control. • Fine-tuning of pilot injection timing and duration improved the engine efficiency and emissions. • Increasing EGR rate stabilized emissions, with notable reductions in NOx and CO levels. • Adjustment of the main injection timing positively impacted combustion characteristics. • Increasing the injection pressure resulted in notable reductions in CO and PM emissions. [ABSTRACT FROM AUTHOR]

When compared to other internal combustion engine types (SI engine, CI engine), the gasoline compression ignition engine (GCI engine) offers a promising and efficient way to enhance heat efficiency and less harmful emissions. The development of new engine technologies is aimed at optimizing the performance of GCI engines by allowing them to operate more efficiently at part load and using lower octane gasoline fuel under higher compression ratios. The GCI engine struggles to cope with a large amount of smoke, soot, HC and CO, and it is not very stable when operating at a low load or when it is exposed to high load conditions, which can cause autoignition. This study will introduce certain technologies, such the strategy for dealing with exhaust gas recirculation (EGR) and oxygen content, that assist in resolving the issues faced by the GCI engine. The research results show that the ignition delay tends to decrease with an increase in EGR. The ignition delay reaches its minimum value at 20% EGR with GB05 fuel. The maximum pressure in the combustion chamber of a GB05-fueled engine can be improved at 20% EGR. The engine's thermal efficiency and NOx emissions decrease, while CO and HC emissions increase with increasing EGR. The increase in oxygen content led to a decrease in ignition delay and lift-off length. [ABSTRACT FROM AUTHOR]

As a novel ignition approach, nanosecond repetitively pulsed discharge (NRPD)-based non-thermal plasma offers significant benefits such as low energy consumption, and lean operating conditions. However, there is no investigation conducted on the early flame kernel formation and development induced by non-thermal plasma. Therefore, in this paper, experiments of conventional spark and non-thermal plasma ignition systems in constant volume combustion chamber (CVCC) are conducted under gasoline engine relevant conditions: wide initial ambient pressures (6.5, 8.3, 11.3 bar), a range of equivalence ratios (0.7–1.0), EGR rates (10−25%), and cross flow speeds (0–30 m/s). The discharge energy of non-thermal plasma is of around 210 mJ, while a single spark event can generate energy from 65 mJ to 83 mJ depending on ambient conditions. A consecutive spark strategy is adopted to guarantee comparable total input energy to non-thermal plasma. The ignition delay and combustion phase obtained from the chamber pressure history are calculated. In the meanwhile, flame kernel radius, flame propagation rate, and flame front length ratio via schlieren images are quantified and analyzed. Results showed that the flame initiated by non-thermal plasma can maintain a robust flame kernel and propagates fast. Under high-speed cross flow and high EGR rate conditions, non-thermal plasma can maintain a robust flame kernel at early stage supporting the initial flame kernel to survive and improve its ignition probability. Considering the effects of the EGR ratio and high-speed cross flow on flame kernel development, non-thermal plasma ignition can efficiently enhance the flame propagation and ignition probability. It is also concluded that non-thermal plasma can successfully ignite under lean (equivalence ratio between 0.7–1.0), high-diluted mixture (25% EGR), and high-speed cross flow of 30 m/s within the range of current study. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the interrelationships between key harmful emission components, nitrogen oxides (NOx), and particulate numbers (PNs) in diesel engine exhaust and the control actuators of diesel engines. This research involved conducting a series of experiments under fixed parameters within an engine brake laboratory environment to elucidate these correlations. The objectives of this study were to conduct a comprehensive review of the relevant emissions technology literature and a comparative assessment of particle measurement methods based on dilution ratios and develop innovative aerosol preparation principles tailored to condensation particle measurement. Additionally, this research involved designing and implementing an aerosol preparation unit based on the newly developed principles, along with the creation of test cell control programs using the AVL PUMA Open TST editor interface and Visual Basic. Furthermore, this study was concerned with conducting evaluations of fixed-parameter engine dynamometer tests to explore the functional relationships between the emission of 10/23 nm particles, NOx emissions, common rail pressure variations, and exhaust gas recirculation levels. This study aimed to enhance the understanding of diesel engine emissions dynamics and contribute valuable insights for developing more efficient and environmentally friendly engine control strategies. [ABSTRACT FROM AUTHOR]

This article presents a novel approach to the analysis of heat release in a hydrogen-fueled internal combustion spark-ignition engine with exhaust gas recirculation (EGR). It also discusses aspects of thermodynamic analysis common to modeling and empirical analysis. This new approach concerns a novel method of calculating the specific heat ratio (cp/cv) and takes into account the reduction in the number of moles during combustion, which is characteristic of hydrogen combustion. This reduction in the number of moles was designated as a molar contraction. This is particularly crucial when calculating the average temperature during combustion. Subsequently, the outcomes of experimental tests, including the heat-release rate, the initial combustion phase (denoted CA0-10) and the main combustion phase (CA10-90), are presented. Furthermore, the impact of exhaust gas recirculation on the combustion process in the engine is also discussed. The efficacy of the proposed measures was validated by analyzing the heat-release rate and calculating the mean combustion temperature in the engine. The application of EGR in the range 0-40% resulted in a notable prolongation of both the initial and main combustion phases, which consequently influenced the mean combustion temperature. [ABSTRACT FROM AUTHOR]

In this article, the authors refer to the measurement of acoustic emission, where they found that this methodology can determine the combustion characteristics in the combustion chamber of the engine and thus it is possible to confirm a better combustion process and overall reduction of engine noise after decarbonization. The formation of diesel exhaust soot is also supported by the authors' paper, in which they describe how such soot is formed and what effect the addition of special mixtures to the combustion process has on the formation of such carbon deposits. The article uses BG technologies for deep engine decarbonization, including intake and exhaust parts. This technology is one of many on the market, but it was only with this technology that the authors managed to achieve the relevant results that this article will introduce to. For the test, we selected vehicles that had a problem to pass at the emission control. [ABSTRACT FROM AUTHOR]

The current research investigates the impact of a split fueling strategy combined with several flow rates of exhaust gas recirculation (EGR) on the combustion and emission characteristics of a diesel engine running on B20 waste cooking oil (WCO) biodiesel. A four‐stroke single‐cylinder common rail direct injection engine was employed for experiments. It operates with a B20 blend of WCO biodiesel at 600 bar pressure for varying pilot fueling conditions of 10%, 20%, and 30%. The B20 blend with 30% pilot fuel injection (B20P30) showed excellent performance and emission characteristics compared with B20 blend with 10% pilot fuel injection (B20P10) and B20 with 20% pilot fuel injection (B20P20). However, B20P30 had greater levels of nitrogen oxide (NOx) emissions than those by diesel. EGR discharge levels in 5% increments, ranging from 0% to 15% were introduced to address this issue. The experimental findings revealed that both cylinder peak pressure and heat release rate showed a reduction when the EGR flow rate was enhanced. The recirculation of exhaust gas into the combustion chamber led to a slight increase in the emission levels of hydrocarbon (HC), carbon monoxide (CO), and smoke, as well as a decrease in carbon dioxide (CO2). Nevertheless, the introduction of EGR significantly decreased NOx emissions by 22.94%, 35.05%, and 47.96% for EGR flow rates of 5%, 10%, and 15%, respectively, when compared with the engine operating without EGR. Overall, the two‐stage fueling strategy, B20P30 blended with 10% EGR corroborated to be beneficial in reducing NOx emissions with minimal performance penalties. Although there was a slight uptick in certain emissions, the overall trade‐off between emission reduction and performance was favorable. The culmination of this study is targeting the objectives of sustainable development goal 7 (clean energy) and goal 13 (climate action) to be achieved by 2030. [ABSTRACT FROM AUTHOR]

The primary aim of this research study was to examine the effectiveness and environmental consequences of using Delonix regia biodiesel (DRB) in combination with butanol (BUT), exhaust gas recirculation (EGR), and diesel fuel (D) on a direct injection compression ignition engine operating at a constant speed. This study involved the formulation of five distinct biodiesel blends, namely DRB10% + D90%, DRB20% + D80%, DRB10% + BUT10% + D80%, DRB10% + BUT20% + D70%, and DRB20% + D80% + EGR10%. The inclusion of n‐butanol in a biodiesel blend serves to tackle the problem of inadequate combustion in fuel blends by alleviating the oxygen deficiency that occurs during the combustion process. The findings of the study revealed that the combination of DRB at 10%, BUT at 20%, and D at 70% produced in a significant reduction in specific fuel consumption (SFC) by 11.19% and brake thermal efficiency by 2.62%. Additionally, this combination led to a decrease in exhaust emissions of CO and Smoke, with the exception of HC and NOx, when compared to the use of diesel fuel. The control of HC and NOx emissions can be achieved through the implementation of an exhaust gas recirculation system. The results of this investigation suggest that Delonix regia biodiesel, in combination with a 20% concentration of n‐butanol, has potential as a viable alternative fuel choice that may be utilized without necessitating any engine modifications. [ABSTRACT FROM AUTHOR]

Purpose: The mainstay of treatment for metabolic dysfunction-associated steatotic liver disease (MASLD) is weight loss. Endoscopic gastric remodeling (EGR) and glucagon-like peptide-1 receptor agonist (GLP-1RA) are effective weight loss therapies. This study aims to assess the effect of combining EGR with GLP-1RA on liver-related outcomes and weight profile. Materials and Methods: This is a retrospective study of a prospectively collected registry of patients with MASLD and compensated advanced chronic liver disease (cACLD) who underwent EGR. Patients were categorized as (1) monotherapy: EGR alone and (2) combination therapy: GLP-1RA prescribed within 6 months prior to or after EGR. Outcomes included changes in noninvasive tests of hepatic fibrosis, weight profile, and insulin resistance status at 12 months. Results: Thirty patients (body mass index 40.7 ± 9.3 kg/m2) were included. Of these, 12 patients (40%) underwent EGR monotherapy, and 18 patients (60%) underwent EGR + GLP-1RA combination therapy. Combination therapy group experienced greater improvements in fibrosis compared to monotherapy group (alanine aminotransferase: reduction by 55 ± 23% vs 29 ± 22% (p = 0.008), NAFLD fibrosis score: reduction by 181 ± 182% vs 30 ± 83% (p = 0.04), liver stiffness measurement on transient elastography: reduction by 54 ± 12% vs 14 ± 45% (p = 0.05)). There were greater reductions in hemoglobin A1c and homeostatic model assessment for insulin resistance in combination therapy compared to monotherapy (p < 0.05). At 12 months, the combination therapy group experienced 18.2 ± 6.6% TWL, while monotherapy group experienced 9.6 ± 3.3% TWL (p = 0.004). Conclusions: In patients with MASLD and cACLD, combination of EGR with GLP-1RA is associated with greater improvements in hepatic fibrosis, weight profile, and insulin resistance compared to EGR alone. [ABSTRACT FROM AUTHOR]

The application of mechanisms such as exhaust gas recirculation (EGR) coupled with variable valve timing (VVT) and a variable geometry turbocharger (VGT) can improve engine efficiency; however, the energy laws and loss distribution after EGR, VVT, and VGT changes are unclear, restricting the optimization of engine structures and corresponding strategies. Herein, a six-cylinder engine is studied, revealing that the cooling loss of the high-pressure (HP) EGR loop is an important factor affecting the engine energy distribution. The cooling loss accounts for 10.00%–20.00% of the total energy, with an average increase of 1.73%, surpassing other energy losses growth rates. The low-pressure (LP) EGR loop considerably reduces cooling losses. The cooling loss of the LP EGR loop is only 64.05% of the HP EGR loop at a 20% EGR rate. When the EGR rate is . 10%, the resulting lower cooling losses effectively improve the engine efficiency and the indicated thermal efficiency (ITE) of the LP EGR loop is 0.20%–0.33% higher than that of the HP EGR loop; when the EGR rate is 21%, the ITE of the LP EGR loop reaches 49.52%. By studying the variation in exergy with operating parameters, it is found that while increasing the EGR rate from 15% to 20%, the proportion of available exergy increases by adjusting the VVT to 285 crank angle after top dead center (CA ATDC) or adjusting the VGT to 47.5% under the original operating scheme of the LP EGR loop (2146 CA ATDC; VGT = 42.5%). The available exergy increases from 71.22%–71.42% (2146 CA ATDC; VGT = 42.5%; original device) to 71.88%–71.58% (2146 CA ATDC; VGT = 47.5%) and 72.02%–72.21% (285 CA ATDC; VGT = 42.5%). This study explores the energy distribution under different operating schemes, providing theoretical guidance for further improving the thermal efficiency of the entire device. [ABSTRACT FROM AUTHOR]

The present study utilized the ab initio atomistic thermodynamics technique to assess the stability of pure carbon dioxide and pure methane on the calcite(10.4) systems. The stability of configurations 0.5 ML-A2, 0.75 ML-A2, and 0.75 ML-A1 in CH4/calcite (10.4) systems was shown to be considerable, but only within a limited range of chemical potential. The 1.0 ML-A1 and 1.0 ML-A2 systems of CH4/calcite (10.4) demonstrated remarkable stability throughout a wide range of chemical potentials. The predominant stable forms for CO2/calcite (10.4) systems are the 1.0 ML-B2 and 1.0 ML-A4 structures. The surface free energy phase diagrams demonstrate that CO2 is more favourable than CH4 for adsorption on the calcite (10.4) surface. Paper type: Short communication paper [ABSTRACT FROM AUTHOR]

This paper comprehensively reviews the role of geomechanical and petrophysical studies in CO2- enhanced gas recovery and/or CO2 storage following CO2 injection in shale gas reservoirs. In order to achieve CO2-enhanced gas recovery (CO2-EGR) from shale reservoirs and/or CO2 storage in shale reservoirs, numerical models and designs rely on an effective appraisal of the target reservoir. This paper analysed the geomechanical and petrophysical characteristics that were taken into account while constructing models for a successful CO2-EGR, in addition to examining assessments of shale reservoirs undertaken in diverse fields of research. The factors were weighted based on their importance in distinct shale reservoir settings. Natural fracture system, fracture conductivity, hydraulic fracture halflength, unconfined compressive strength (UCS), Young's modulus, Poisson's ratio, and other geomechanical and petro-physical parameters are important throughout the entire process, which also includes CO2 injection, residual hydrocarbon mobilisation, variations in stress and strain during hydrocarbon production, and the subsequent impact on fracture network conductivity. This research will also give recommendations on how to improve the previously described geomechanical and petrophysical characteristics in order to achieve effective CO2-enhanced gas recovery and/or CO2 storage in shale gas reservoirs. The energy sector's goal is to continue employing unconventional resources to provide sustainable energy. As a result, this review study will contribute significantly to our understanding of how to reduce subsurface failure in CO2-EGR fracturing and injection, as well as refracturing and CO2 injection in depleted shale gas reservoirs for CO2 storage. [ABSTRACT FROM AUTHOR]

Equivalent combustion natural gas engines typically utilize exhaust gas recirculation (EGR) systems to tackle their high thermal burden and NOx emissions. Variable nozzle turbochargers (VNT) can increase the engine intake and EGR rate simultaneously, resulting in NOx reduction while ensuring robust power performance. Using a VNT along with engine bench testing, the impact of VNT- and EGR-coordinated control on the performance and emissions of equivalent combustion natural gas engines was investigated under different operating conditions. Subsequently, multi-objective optimization was performed using a support vector machine. The results demonstrated that the use of VNTs in equivalent combustion natural gas engines could bolster the capacity to introduce EGR under several operative conditions and extend the scope of EGR regulation, thereby decreasing the engine's thermal burden, improving fuel efficiency, and curbing emissions. Owing to the implementation of a multi-objective optimization method based on a support vector regression model and NSGA-II genetic algorithm, VNT and EGR control parameters could be optimized to slightly improve the economy and significantly reduce NOx emissions while maintaining the original engine power performance. At 20 operating points optimized for validation, brake-specific fuel consumption (BSFC) and NOx decreased by 0.94% and 47.0%, respectively, and CH4 increased by 3.7%, on average. [ABSTRACT FROM AUTHOR]

Due to the common operating characteristics of medium duty (MD) gasoline engines, achieving higher load at the expense of fuel efficiency is not an acceptable tradeoff. EGR dilution-stoichiometric combustion can suppress the knocking and improve the thermal efficiency, but has problems such as slow combustion rate and poor combustion stability, which have limitations in optimizing combustion for MD gasoline engines with strong swirl. The experimental investigations in this study focus on the interaction of charge motion and EGR on anti-knock performance and thermal efficiency under different load conditions, and verifies the potential to improve the thermal efficiency of inclined swirl combustion system. The results show that at low-medium load, the tumble-dominated inclined swirl scheme can enhance the effectiveness of EGR in knock suppression, thus reducing the introduction of EGR to avoid its adverse effects on the combustion duration. At medium-high load, although the above benefit wears off, it can enhance the anti-knock performance and thus advance the spark timing by increasing the EGR tolerance. The EGR ratio corresponding to the highest thermal efficiency increases with higher load. The difference in the in-cylinder flow field will affect the combustion rate in a high EGR dilution and high load condition. The scheme adopting the compound intake ports and inverse cuneiform-shaped combustion chamber can improve both EGR tolerance and initial combustion rate under high EGR dilution, with the most significant improvement in thermal efficiency, and the improvement range will increase along with the increase of load. [ABSTRACT FROM AUTHOR]

The simultaneous reduction of Green-House Gases (GHG) and criteria pollutants is the main target of current Internal Combustion Engines (ICE) development. Hydrogen (H2) fueling is one of the best options available in both regards, as it does not emit tailpipe CO2 as well as significantly abates all criteria pollutants already at engine-out level. However, optimizing hydrogen combustion in order to exploit the fuel proprieties at best is a challenging task due to the very particular properties of the fuel. In fact, H2 combustion in ICE promotes a very clean, fast and complete combustion process, with extremely low HC, CO, and PM engine-out emissions stemming only from lubricant oil. The usage of lean-boosted and EGR-diluted combustion strategies can significantly contribute to raise the brake thermal efficiency and lower the NOx emission to extremely low levels. To this end, the Authors tested a 0.5 L single cylinder engine featuring an optimized PFI layout and dedicated piston bowl profile for a retrofitted Diesel operating as H2 monofuel, in SI mode. In this paper, the authors discuss the effect of the main engine parameters, extensively investigated by means of Design of Experiments (DoE) techniques, as well as the effect of dilution and EGR to promote clean and efficient hydrogen combustion, in order to recommend the most effective practices. [ABSTRACT FROM AUTHOR]

The objective of this study is to develop a 1D CFD simulation model to identify the optimal design parameters, using GT-POWER prior to the optimization of a new rotary engine derived from a three-lobe gerotor pump (GP3 RTE) based on 3D CFD simulation. The models were compared based on their respective development stages (steps 1–4) to ascertain the impact of each parameter on performance. The step 4 model, which exhibited a similar trend to that observed in the 3D CFD results, was selected for further analysis and validation. The developed model accurately predicted GP3 RTE performance in terms of fuel consumption, indicated power, efficiency, and exhaust gas reticulation (EGR) behavior, approaching the accuracy of the CONVERGE model. Furthermore, the optimal intake/exhaust port locations and operating conditions of the GP3 RTE were derived using the developed step 4 model. The model provided a convenient and powerful tool for obtaining basic information regarding the unique behavior of the GP3 RTE, thereby enabling the optimization of the design parameters without the necessity for time-consuming three-dimensional design modifications.

This study deals with enhancing the energy efficiency with ultra-low emissions and extending the operating range (maximum load limit) of dimethyl ether (DME) fueled homogeneous charge compression ignition (HCCI) engine using hydrogen and exhaust gas recirculation (EGR). In the neat DME mode, the possible maximum load limit with controlled auto-ignition (CAI) was found as 24% (BMEP of 1.67 bar). Beyond 24% load, the knocking was observed with an advanced combustion phase, and shortened combustion duration resulted in uncontrolled auto-ignition (UAI) combustion. The addition of EGR extended the maximum load limit to 52% (BMEP of 3.62 bar) (60% EGR). Near-zero levels of NO x , zero smoke, and marginal CO and HC emissions reduction were observed with the optimized EGR rate (35%). The hydrogen fuel addition along with DME at an optimized EGR rate resulted in combustion phase retardation with the elimination of the low-temperature reaction (LTR) region. The energy efficiency (EE) and indicated thermal efficiency (ITE) increased along with zero smoke emission, ultra-low NO x , CO, and HC, and lower CO 2 emissions till 12% of hydrogen energy share (HES). Thus, the combined strategy of EGR and hydrogen could effectively extend the operating range with ultra-low emissions levels. • EGR extended the maximum load limit and control knock in DME HCCI engine. • Higher energy efficiency and indicated thermal efficiency with hydrogen. • Zero smoke emission with Ultra-Low NO x , CO, CO 2 , and HC emissions. • Elimination of cool-flame (LTR) region with hydrogen. • DME and hydrogen could be a dual fuel combination for HCCI combustion. [ABSTRACT FROM AUTHOR]

Hydrogen is seen as a prime choice for complete replacement of gasoline so as to achieve zero-emissions energy and mobility. Combining the use of this alternative fuel with a circular economy approach for giving new life to the existing fleet of passenger cars ensures further benefits in terms of cost competitiveness. Transforming spark ignition (SI) engines to H2 power requires relatively minor changes and limited added components. Within this framework, the conversion of a small-size passenger car to hydrogen fueling was evaluated based on 0D/1D simulation. One of the methods to improve efficiency is to apply exhaust gas recirculation (EGR), which also lowers NOx emissions. Therefore, the previous version of the quasi-dimensional model was modified to include EGR and its effects on combustion. A dedicated laminar flame speed model was implemented for the specific properties of hydrogen, and a purpose-built sub-routine was implemented to correctly model the effects of residual gas at the start of combustion. Simulations were performed in several operating points representative of urban and highway driving. One of the main conclusions was that high-pressure recirculation was severely limited by the minimum flow requirements of the compressor. Low-pressure EGR ensured wider applicability and significant improvement of efficiency, especially during partial-load operation specific to urban use. Another benefit of recirculation was that pressure rise rates were predicted to be more contained and closer to the values expected for gasoline fueling. This was possible due to the high tolerance of H2 to the presence of residual gas. [ABSTRACT FROM AUTHOR]

Due to the increasingly stringent emission regulations and the growing concern about energy hazard, natural gas (NG) has emerged as an alternative fuel with abundant reserves, low cost, high combustion performance and low pollutant emissions. In this study, a NG high pressure direct injection (HPDI) model is embedded in a Cummins ISX marine medium-speed four-stroke natural gas-diesel dual fuel (NGDDF) engine model. The strategies with different injection overlap of NG and pilot diesel oil (PDO) and different exhaust gas recirculation (EGR) were investigated, the following conclusions are drawn. At the same EGR rate, the injection start point of NG (SOING) has impact on the compression end pressure to some extent, while the injection end point of the pilot diesel oil (EOIPDO) makes little difference to the compression end pressure. With the increase of SOING, the maximum pressure (PMax) rises gradually. When the SOING remains unchanged, the longer the pilot diesel oil (PDO) injection lasts, the higher the PMax. The heat release rate (HRR) of HPDI engine has two peaks. The first one decreases as the EGR rate rises, while the other is inversely proportional only to the EGR rate. As the EGR rate increasing, the position of the second peak of HRR is increasingly delayed, irrespective of the injection strategy used. At the same EGR rate, the overlapping injection strategy has only a limited impact on the maximum in-cylinder temperature (about 42 K) and the soot emission (about 0.003 g/kwh). The first stage of nitrogen oxides (NOX) generation is closely related to the EGR rate. The higher the EGR rate, the longer the interval between the first and second stage of NOX generation. Though both reasonable injection overlap and delay of EOIPDO are conducive to reduce pollutant emissions, it remains necessary to delay the position of the overlap angle as much as possible, and the emission reduction effect of injection overlap will diminish as the EGR rate increasing. Either the injection overlap formed by delaying EOIPDO or advancing SOING has a positive impact on indicated mean effective pressure (IMEP). The introduction of EGR will increase indicated specific fuel consumption (ISFC) of the engine, while the injection overlap strategy can be used to reduce it by 5.35 g/kwh. In order to meet the Tier III standard, the combination of injection strategy B and 18% EGR can be considered as the most effective solution for soot, ISFC and IMEP factors. [ABSTRACT FROM AUTHOR]

The natural gas high pressure direct injection (HPDI) engines have attracted attention due to their high combustion stability and thermal efficiency comparable to diesel. However, the nitrogen oxides (NOx) emissions from HPDI engines remain high. In this study, the coupling effects of the exhaust gas recirculation (EGR) and pilot diesel quantity were investigated on a four stroke HPDI engine by simulation. Three pilot diesel quantities and four EGR rates were involved, and the combustion and emission characteristics of the engine were compared and discussed. The results show that with increasing EGR rate, the maximum combustion pressure (Pmax) decreases with different pilot diesel quantity, and the crank angle corresponding to the maximum combustion pressure (CPmax), the crank angle corresponding to the maximum heat release rate (CHRRmax) and the crank angle corresponding to the 50% cumulative heat release (CA50) are all pushed back. NOx emissions decrease gradually with the increase of EGR rate, but soot, unburned hydrocarbon (HC) and carbon monoxide (CO) emissions and methane escape all increase and the indicated thermal efficiency (ITE) decreases. The traditional "trade-off" relationship between NOx and soot emissions still exists on HPDI engine and becomes more obvious as the quantity of pilot diesel increases. NOx and soot emissions can be well balanced at moderate EGR rate. Increasing the quantity of pilot diesel can partially offset the hysteresis effect of EGR on the combustion process. And when the EGR rate is controlled within 30%, increasing the quantity of pilot diesel is beneficial to reduce HC and CO emissions and methane escape. By increasing the quantity of pilot diesel coupled with a moderate level of EGR rate, it is possible to significantly reduce NOx emissions while maintaining the ITE, methane escape and unburned diesel, HC and CO emissions at the same level as without EGR. But soot emissions will increase substantially. [ABSTRACT FROM AUTHOR]

In this present work, the impacts of exhaust gas recirculation (EGR) on exhaust emissions of a diesel engine powered with the blending of butanol with mineral diesel under different engine loads were studied. Experimental tests were performed using butanol‐diesel blends on a single cylinder, constant speed, direct injection (DI) unmodified diesel engine at different proportions by vol%. A higher alcohol—Butanol of 10%, 20%, and 30% blended with mineral diesel fuel. Three different EGR rates of 10 to 30% were employed to reduce the oxides of nitrogen (NOx) emissions that prevailed at higher engine loads. Experimental results revealed that by increasing the EGR rates reduces nitrogen oxide emissions by up to 32% at higher loads. Whereas smoke opacity barely raised to an EGR rate of 20%. There was a rise in hydrocarbon (HC) emissions and a slight surge in carbon monoxide (CO) emissions found with butanol‐diesel blends rather than mineral diesel. NOx emissions were decreased by 29% for 70% Diesel + 30% Butanol (Bu30) blend with EGR 30% than mineral diesel fuel. There is an increase in smoke opacity with engine load because of the burning of a higher amount of energy to generate higher brake power. Smoke opacity is decreased to 68.9% using Bu30 than conventional diesel. Overall, it was found that blends of 30% of butanol and 70% of diesel can be employed in existing unmodified diesel engines. [ABSTRACT FROM AUTHOR]

The global automotive industry is facing significant challenges, including dwindling fossil fuel reserves, rising crude oil prices, and increasingly strict emission regulations. To address these concerns, this study investigates the impact of the compression ratio (CR) and exhaust gas recirculation (EGR) on the performance and emissions of a common rail direct injection (CRDI) diesel engine fuelled with a 20% blend of tamarind seed methyl ester (TSME 20) biodiesel. The study employed an open-type electronic control unit to implement pilot fuel injection at a rate of 30%, 23° before the top dead centre (TDC), and at a higher pressure of 600 bar. Three CRs (16:1, 18:1, 20:1) and two types of EGR (hot and cold EGR at 10%) were evaluated. Diesel fuel at CR 18 was used as a baseline for comparison. The experimental procedure involved conducting tests with TSME 20 at CR 16, 18, and 20. Subsequently, TSME 20 at CR 20 + Hot EGR 10% and TSME 20 at CR 20 + Cold EGR 10% were examined. The results showed that TSME 20 operated at a higher CR (CR 20) exhibited improved diesel engine performance and significant reductions in harmful exhaust emissions. Additionally, cold EGR at 10% was more effective in reducing CO, CO2, and NOx emissions from TSME 20 than hot EGR. The findings of this study provide valuable insights into optimizing diesel engine operation to achieve a balance between performance enhancement and emission reduction through tamarind seed biodiesel blends and different EGR techniques. The implementation of these strategies holds considerable potential in addressing the automotive industry's challenges, including ecological considerations and fuel price fluctuations. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the interrelationships between key harmful emission components, nitrogen oxides (NOx), and particulate numbers (PNs) in diesel engine exhaust and the control actuators of diesel engines. This research involved conducting a series of experiments under fixed parameters within an engine brake laboratory environment to elucidate these correlations. The objectives of this study were to conduct a comprehensive review of the relevant emissions technology literature and a comparative assessment of particle measurement methods based on dilution ratios and develop innovative aerosol preparation principles tailored to condensation particle measurement. Additionally, this research involved designing and implementing an aerosol preparation unit based on the newly developed principles, along with the creation of test cell control programs using the AVL PUMA Open TST editor interface and Visual Basic. Furthermore, this study was concerned with conducting evaluations of fixed-parameter engine dynamometer tests to explore the functional relationships between the emission of 10/23 nm particles, NOx emissions, common rail pressure variations, and exhaust gas recirculation levels. This study aimed to enhance the understanding of diesel engine emissions dynamics and contribute valuable insights for developing more efficient and environmentally friendly engine control strategies.

This article presents a novel approach to the analysis of heat release in a hydrogen-fueled internal combustion spark-ignition engine with exhaust gas recirculation (EGR). It also discusses aspects of thermodynamic analysis common to modeling and empirical analysis. This new approach concerns a novel method of calculating the specific heat ratio (cp/cv) and takes into account the reduction in the number of moles during combustion, which is characteristic of hydrogen combustion. This reduction in the number of moles was designated as a molar contraction. This is particularly crucial when calculating the average temperature during combustion. Subsequently, the outcomes of experimental tests, including the heat-release rate, the initial combustion phase (denoted CA0-10) and the main combustion phase (CA10-90), are presented. Furthermore, the impact of exhaust gas recirculation on the combustion process in the engine is also discussed. The efficacy of the proposed measures was validated by analyzing the heat-release rate and calculating the mean combustion temperature in the engine. The application of EGR in the range 0-40% resulted in a notable prolongation of both the initial and main combustion phases, which consequently influenced the mean combustion temperature.

Abstract Rapid depletion of fossil fuels required the development of alternate and sustainable fuel sources that could replace conventional fuel while having no negative environmental impact. Combining hydrogen induction with biodiesel ensures strict emission standards and lowers energy consumption compared to conventional fuels. In this study, the performance, emissions, and combustion of a CI engine for Syzygium cumini (B20) were assessed and compared to diesel fuel while using a fixed amount of hydrogen flow rate (6L/m). Throughout the experiment, an exhaust gas recirculation (EGR) technology of 10% and 20% and a constant engine speed of 1500 rpm at varying engine load circumstances were used. When hydrogen is added to B20, it decrease the emissions of carbon monoxide (CO), unburned hydrocarbons (UHC), brake thermal efficiency (BTE), and brake specific energy consumption (BSEC). At maximum load, the use of the EGR system decreased the exhaust gas temperature (EGT) by 13.4% and nitrogen oxide (NOX) emission by 25%, but it had a negative impact on BTE, BSEC, as well as other emission parameters including CO and UHC. Therefore, using hydrogen in dual fuel mode in a CI engine enhances performance and lowers exhaust emissions, while using the EGR approach reduces NOX emissions.

A mixture of diesel, biodiesel (from algae), and butanol was mixed with nano-titanium dioxide at 50 and 100 parts per million in this study under post-injection (PI) strategy and two rates (10 % and 20 %) of exhaust gas recirculation (EGR). In the literature, few studies have investigated how PI strategies effect on engine emissions and combustion performance from mixture of B16M20 by butanol (16 %), microalgae biodiesel (15 %) and diesel with variable EGR rates. To gain a better understanding of the effects of EGR rates on diesel engines running with B16M20 mixture, this study was conducted. The final fuel type test used B16M20 treated with 50 ppm and 100 ppm of nano-TiO2. Fuel specific fuel consumption (BSFC) increased by 3 % for both diesel and B16M20 when EGR was used, but PI reversed this trend. Nanoparticles added to B16M20 blend significantly contributing in decreased BSFC to 6.47 %. 100 ppm nano-TiO2 added to 10 % of EGR, along with PI, can achieve the same or enhance better brake thermal efficiency (BTE) by 4.53 % than pure diesel. The lowest NOX levels by 26.48 % were achieved with 100 ppm nano-TO2 and B16M20 with 20 % EGR. Because of EGR's high heat capacity and dilution effect, higher EGR rates result in higher soot levels. As a result of the PI strategy, the soot levels emitted from B16M20 reduced by 28.57 % compared with diesel fuel. At PI strategy presence (W PI) and adding 100 ppm nano-TiO2 into the B16M20 blend resulted in the lowest PM concentrations by 59 % compared to the diesel and without PI (W/O PI). PM emissions were significantly reduced at temperatures below 600 °C from B16M20 blend combustion with delay injection, 10 % EGR, and 100 ppm nano-TiO2. Soot oxidation was minimized through EGR, and enhanced by nano-TiO2. Adding this 100 ppm of nanoparticles to diesel fuel produced more reactive soot than diesel fuel alone.

The efficient application of oxygen-containing clean fuels in engines has always been a research focus. With the increase in ethanol production, the output of fusel as a co-product is also increasing. The application of fusel is also an effective way to lessen the consumption of fossil fuels. Therefore, the influences of fusel on performance and emissions were investigated in the current study on a six-cylinder heavy-duty compression-ignition engine and revolved around the WHSC test cycle. The three test fuels were diesel, F20NW (the volume proportion of anhydrous fusel is 20%, and the rest is pure diesel), and F20WW (the volume proportion of hydrous fusel is 20%). The addition of fusel improved BTE, reduced NOx and soot emissions, and thermal efficiency and emissions were further improved in combination with EGR optimization. In terms of WHSC, the improvement effect of hydrous fusel was the best. The equivalent fuel consumption, NOx, soot, and CO2 emissions of F20WW were reduced by 1.77%, 37.49%, 17.38%, and 1.32%, respectively, with the optimization of EGR compared with pure diesel. The addition of 20% hydrous fusel combined with the introduction of EGR can be directly applied to existing diesel engines and achieve a simultaneous reduction in fuel consumption and emissions. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of compression ratio (CR) with the use of exhaust gas recirculation (EGR) technology on the performance of combustion characteristics at different CRs and engine loads; the brake thermal efficiency (BTE), specific fuel consumption (SFC), volumetric efficiency (VOL.EFF), exhaust gas temperature, carbon dioxide emission (CO2), hydrocarbons (HC), nitrogen oxides (NOx), and oxygen content (O2). The single‐cylinder, four‐stroke compression ignition engine was run on a mixture of diesel and biodiesel prepared from Iraqi waste cooking oil at (B0, B10, B20, and B30). A comparison has been achieved for these combustion characteristics at different blends, load, and CRs (14.5, 15.5, and 16.5) at 1500 rpm constant engine speed. The transesterification process is used to produce biodiesel and ASTM standards have been used to determine the physical and chemical properties of biodiesel and compare them to net diesel fuel. The preliminary conducting tests indicated that engine performance and emissions improved with the B20 mixture. Experimental test results showed an increase in BTE when CR increased by 17% and SFC increased by 23%. It also found a higher VOL.EFF by 6% at higher pressure ratios. A continuous decrease in BTE values and an increase in SFC were sustained when the percentage of biodiesel in the mixture was increased. Emissions of carbon dioxide, HC, and NOx increased by 12%, 50%, and 40%, respectively, as CR reached high values. NOx increased with the addition of biodiesel to 35%, which necessitated the use of EGR technology at rates of 5% and 10%. The results indicated that the best results were obtained in the case of running the engine with a mixing ratio of B20 with the addition of 10% EGR, NOx decreased by 47% against a slight increase in other emissions. [ABSTRACT FROM AUTHOR]

The effects of fuel components on EGR and lean limits in multi-cylinder gasoline engines were investigated. The combustion stabilities for various fuel components varying the olefin contents and adding oxygenate components such as ethanol and ETBE were especially evaluated. The experimental results show that the fuel components have a significant impact for the EGR and lean limits. It was found that the fuel containing a large volume of olefin with ethanol could extend not only EGR and lean limit but also knock limit. We revealed the potentiality for improving thermal efficiency with adjusting fuel components. [ABSTRACT FROM AUTHOR]

Traditional selective catalytic reduction aftertreatment technologies used to reduce N O x are very limited at exhaust temperatures below 175 ° C. Therefore, under these low engine load conditions, having effective in-cylinder control of N O x emissions is important. Previous work by the authors explored the effect of fuel physical properties on the ability to control N O x in-cylinder. That work was limited to one direct injection near top dead center. Modern diesel high-pressure fuel systems have the capability of five or more injections in one engine cycle. A higher-volatility diesel fuel and high amounts of exhaust gas recirculation to delay ignition could provide an opportunity for reduction in engine-out N O x through an increased level of fuel premixing. By appropriately timing multiple short injections, a more optimal distribution of fuel in-cylinder may be achieved, which could reduce N O x while maintaining an efficient combustion phasing. A computational fluid dynamics model previously validated against experimental data was used to explore several injection strategies with increased levels of fuel premixing to assess the potential trade-offs between N O x and CO/unburned hydrocarbon (UHC) emissions and thus reduce reliance on the aftertreatment system for N O x control. The results show that the devised injection strategies resulted in an increased level of fuel premixing. However, none of the attempted injection strategies resulted in significant N O x reductions, and all strategies showed a significant increase in CO and UHC emissions. [ABSTRACT FROM AUTHOR]

With increasingly stringent emissions regulations, there are growing demands for the transient performance of diesel engines. This study conducted a transient bench test on a two-stage turbocharged heavy-duty diesel engine to optimize its performance during a load increase (20% to 100% in 1 s) at a constant speed (1200 RPM) transient process. The results showed that the transient control scheme using the low-pressure EGR system resulted in a 42.1% reduction in the peak value of soot emission, a 24.8% decrease in the peak value of NOx emission, a 9.14% decrease in ISFC and a 30.6% increase in maximum IMEP achieved in 1 s, compared to the steady-state optimization control scheme without EGR. Transient control scheme using the high-pressure EGR system resulted in a 24.4% reduction in the peak value of soot emission, a 31.8% reduction in the peak value of NOx emission, a 9.52% reduction in ISFC, and a 31.7% increase in maximum IMEP achieved in 1 s. The comparison of high and low-pressure EGR systems revealed that the low-pressure EGR system produced lower compromising emissions, while alterations in control parameters for the diesel engine with a high-pressure EGR system had a more significant impact on the transient process performance. [ABSTRACT FROM AUTHOR]

The collaborative control of intake parameters coupled with pilot injection timing (PIT) can extend the working load range of pilot diesel injection (PDI) ignition natural gas engines with high efficiency and clean combustion. The author conducted the test under heavy load conditions where the engine speed was 1000 r/min and the indicated mean effective pressure was 1.7 MPa. Based on the experimental results of combustion and emission characteristics, the simulation results of the generation and consumption process of active groups as well as the chemical reaction kinetics analysis, the results indicate that increasing the intake pressure (pin) can improve the overall activity of the mixture in the cylinder, resulting in higher ITEg and lower emissions; the application of exhaust gas recirculation (EGR) can inhibit the oxidation reaction of fuel and knock occurrence. High pin, suitable EGR rate, and advanced PIT can achieve high thermal efficiency and low total hydrocarbon and carbon monoxide emissions. For example, when pin was 0.34 MPa, the EGR rate was 40%, the PIT was −4°CA ATDC, and the ITEg can reach 50.46%. Simultaneously, the total hydrocarbon emission was 3.99 g/kWh, the carbon monoxide emission was 2.75 g/kWh, and the nitrogen oxides emission was 0.42 g/kWh. [ABSTRACT FROM AUTHOR]

Aiming to the global energy insecurity due to extensive dependence on fossil fuels, hydrogen is supposed to provide relief by researchers. However, employed to combustion engines, this green fuel leaves hazardous NOx and limits output due to low volumetric energy content. Hence, improving operating parameters like compression ratio and manifold pressure, and NOx mitigating technique like EGR may prove a boon. Therefore, in the present study, combustion and NOx emission behavior of the SI-engine is studied under variable manifold air pressure (MAP) (up to 130 kPa) and EGR (up to 15%) at compression ratio 14:1. The outcomes shows the flame development increased by 1.24%, while flame propagation is increased by 1.63% by MAP boosting due to increased air and fuel supply. Cylinder pressure and heat-release rate (HRR) are also surged due to the increased fuel supply to maintain excess-air ratio (λ). However, peak cylinder pressure is retarded due to elongated combustion. The exhaust gas temperature (EGT) is increased by 19.4%, while elevated Tmax is observed to shoot up NOx by 40%. Combustion in improved at low EGR due to reduced λ, and also the specific NOx. At higher EGR rate deteriorated combustion due to increased heterogeneity by high dilution, increasing combustion duration, cooling losses and reducing cylinder pressure, Tmax and EGT. A 9.33% and 5.67% increase in CA10 and CA10–90 respectively is observed for 130 kPa at 15% EGR than no EGR. The rapid reduction in oxygen and higher heterogeneity reducing residence time, resulted in rapid drop (33% at N/A to 42.68% at 130 kPa for 15% EGR) in NOx by EGR. The coefficient variation is reduced by boosting MAP but increased severely at higher EGR, which restricts operating EGR rate. [ABSTRACT FROM AUTHOR]

In this study, the effects of intake port injection of methane and direct of injection diesel on emissions and the combustion of a light-duty RCCI engine were numerically researched. In this way, AVL Boost software was used for 1-dimensional simulation of the combustion process and emission estimation. Higher octane number methane gas was mixed with air from the intake port, while lower octane number diesel fuel was injected directly into the combustion chamber during the compression stroke. Methane gas was injected at a rate of 65% and diesel fuel at a rate of 35%. The diesel injected directly into the combustion chamber was sprayed at a rate of 5% between 0 and 35 °CA with 8 different injection timings after the main injection. In the model engine, 50% high EGR rate was applied in all combustion modes. The results showed that these parameters have significant effects on performance and emissions. The results in summary; NOx emission reduced at all engine speeds with delayed diesel post-injection timing. The maximum drop of NOx emission was 57.34% with Post15. Although the addition of methane slightly increased the soot emission, it was significantly reduced by the simultaneous addition of methane and application of post-injection strategies of diesel fuel. The soot emission was reduced by 58.85% with the Post35 injection strategy.

Equivalent combustion natural gas engines typically utilize exhaust gas recirculation (EGR) systems to tackle their high thermal burden and NOx emissions. Variable nozzle turbochargers (VNT) can increase the engine intake and EGR rate simultaneously, resulting in NOx reduction while ensuring robust power performance. Using a VNT along with engine bench testing, the impact of VNT- and EGR-coordinated control on the performance and emissions of equivalent combustion natural gas engines was investigated under different operating conditions. Subsequently, multi-objective optimization was performed using a support vector machine. The results demonstrated that the use of VNTs in equivalent combustion natural gas engines could bolster the capacity to introduce EGR under several operative conditions and extend the scope of EGR regulation, thereby decreasing the engine’s thermal burden, improving fuel efficiency, and curbing emissions. Owing to the implementation of a multi-objective optimization method based on a support vector regression model and NSGA-II genetic algorithm, VNT and EGR control parameters could be optimized to slightly improve the economy and significantly reduce NOx emissions while maintaining the original engine power performance. At 20 operating points optimized for validation, brake-specific fuel consumption (BSFC) and NOx decreased by 0.94% and 47.0%, respectively, and CH4 increased by 3.7%, on average.

In the present research work an optimisation stuy of the Exhaust gas recirculation (EGR) rate for MIS adopted POME fueled CRDI Diesel Engine fitted with TRCC was carried out. The engine was operated with injection parameters such as 900 bar, 7 holes and 10° BTDC which have been optimized for better performance and lower emissions from our previous study. The experiments were carried out by employing an RSM-based D-optimal design, and the relationship between input and output was determined using an ANOVA. Using RSM-ANOVA, mathematical models were built for each result, and the predicted and actual outcomes were compared. With an R2 value greater than 99.34%, the prediction models were discovered to have a strong prediction efficiency. The desirability approach-based optimisation was used to determine the ideal engine operating parameters. EGR rate was varied from 0% to 20% and an MIS of 40 + 20+40 has been adopted for the engine. An EGR rate of 10% is optimized from the viewpoint of NOx reduction and penalty in power output which results in a decrease in brake thermal efficiency by 2.90%, peak pressure by 4.8%, heat release rate by 8.8% and oxides of nitrogen (NOx) by 1.35%. A drastic increase in emissions such as carbon monoxide by 5.8%, unburnt hydrocarbon by 13.3% and smoke by 20.6% was also observed. Both the ANN and RSM models correctly fit the experimental data, producing R2 values that ranged from 95.5% to 98.5%, respectively. The findings show that RSM and ANN are both highly accurate modelling approaches. Additionally, as compared to RSM, the ANN model's predictive accuracy was marginally better. This research could have a wide range of applications in CI engine-powered transportation systems.

Rapid depletion of fossil fuels required the development of alternate and sustainable fuel sources that could replace conventional fuel while having no negative environmental impact. Combining hydrogen induction with biodiesel ensures strict emission standards and lowers energy consumption compared to conventional fuels. In this study, the performance, emissions, and combustion of a CI engine for Syzygiumcumini (B20) were assessed and compared to diesel fuel while using a fixed amount of hydrogen flow rate (6L/m). Throughout the experiment, an exhaust gas recirculation (EGR) technology of 10% and 20% and a constant engine speed of 1500 rpm at varying engine load circumstances were used. When hydrogen is added to B20, it decrease the emissions of carbon monoxide (CO), unburned hydrocarbons (UHC), brake thermal efficiency (BTE), and brake specific energy consumption (BSEC). At maximum load, the use of the EGR system decreased the exhaust gas temperature (EGT) by 13.4% and nitrogen oxide (NOX) emission by 25%, but it had a negative impact on BTE, BSEC, as well as other emission parameters including CO and UHC. Therefore, using hydrogen in dual fuel mode in a CI engine enhances performance and lowers exhaust emissions, while using the EGR approach reduces NOX emissions. [ABSTRACT FROM AUTHOR]

In compliance with proposed targets of green energy and reduced emissions during the Glasgow summit, the study of blended fuels in internal combustion engines is of great significance. To address this issue, a detailed study of the engine performance and exhaust emissions has been conducted with ternary fuel blends of diethyl ether (DEE), waste soybean cooking oil (WSCO) biodiesel, and ultra-low sulfur diesel (ULSD). Ternary blends were prepared by adding 0–15% v/v DEE with the B35 blend (35% v/v WSCO biodiesel + 65% v/v ULSD), and tests were carried out with 15% EGR. The RSM based modeling and experimental approaches have been used for analysis. With a desirability of 0.961, the ternary blend DEE10B35EGR15 (10% v/v DEE + 90% v/v B35 at 15% EGR) was found to be an optimal blend. The measured responses are 0.272 kg/kWh, 31.47%, 18.94 HSU%, 91 ppm, 0.030%, and 24 ppm for brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), smoke, nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbon (HC) emissions, respectively. An innovative approach to analysis and quantifying the responses to ternary blends with EGR has been presented in the form of mathematical equations for future use and scope. [ABSTRACT FROM AUTHOR]

A single cylinder low powered diesel engine of 3.5kW was modified to run on Common rail direct injection high pressure split injection system. This modified engine was tested to run on the neat diesel with ultra-cooled exhaust gas recirculation. The adjustable working parameters i.e., injection pressures 200bar, 230bar, 250bar, 300bar and 350bar, retarded injection -11°, split injection -54°and -11°. After Top dead center position, Exhaust gas recirculation flow rates 5% & 10% respectively are tested on this engine under two typical operating conditions of ? full load of 0.875kW and ? full load of 2.625kW respectively. Single factor and multifactor orthogonal quadratic regression analysis has been carried to determine the effect of these 4 working parameters on engine emissions NOx. The mathematical equations characterizing the relationship between these 4 operating variables are formed. The equation of the NOx and noise was from the orthogonal regressive test under 1/4 Full load and ? Full load conditions was set as the objective function and the ranges of these 4 working variables are given as the constraint condition. Models of non-linear programming were then formulated and solved by using statistical analytical software. Test results showed that 10% Single Injection generates NOx of 194.87 parts per million while 10% Multiple fuel injection generates 199 while the minimum NOx that can be produced is 134.27. [ABSTRACT FROM AUTHOR]

Major energy production all over the world depends on fossil fuels. Recent research on alternative energy sources has raised major concerns about environmental impacts, future availability, and cost. Pollution from diesel engines also affects the environment negatively. As a result, there is a worldwide concern about reducing the pollutants emitted by diesel engines. In comparison to diesel fuel, biodiesel combustion produces reduced carbon monoxide (CO2) and unburned hydrocarbon (UHC) emissions but higher nitrogen oxide (NOx) emissions. The current study aims to investigate the thermal and chemical effects of exhaust gas recirculation (EGR) on the features of a diesel engine for environmental sustainability. The punnai oil was produced from kernels of punnai seeds and transesterified in two phases using alcohol with the existence of a catalyst. The higher viscosity of punnai oil biodiesel is diluted by mixing it with diesel fuel. Our previous investigation indicated that neat punnai oil biodiesel is a potential fuel; however, the findings showed that the addition of diesel is necessary to obtain acceptable engine performance. In this study, punnai oil biodiesel was mixed at a rate of 20% with diesel (B20) and run in a diesel engine with varied EGR rates under five different engine loads. This combined impact enhanced the maximum heat release rate (HRR) and maximum combustion pressure, according to the findings. The premixed burning fractions were commonly higher at all engine loads, whereas the diffusion combustion fractions were lower. When the centre of the HRR changed toward the top dead centre (TDC), combustion durations remained rather constant. The experimental results revealed the B20 blend at a 10% EGR flow rate produced 6.57% lower BTE, 37.04% higher BSEC, 2.47% higher EGT, 5.13% lower CO, 31.11% higher CO2, 3.13% higher UHC, 8.36% lower NOx, and 4% higher smoke opacity when compared with diesel in a standard diesel engine. [ABSTRACT FROM AUTHOR]

The developments in the field of nano-additives have increased in the recent years due to the desire to reduce the level of exhaust emissions in diesel engines. The soot characteristics of particulate matter (PM) and nitrogen oxides (NOX) were experimentally investigated using two concentrations of titanium dioxide (TiO2) as nano-additives (25 ppm and 40 ppm) blended with C20D (composed of 20% castor oil methyl ester and 80% diesel fuel) and 30% exhaust gas recirculation (EGR). The combustion of C20D + TiO2 increases brake thermal efficiency (BTE) by 2.8% in comparison with neat C20D, while a significant reduction was obtained in BSFC 6.5% and NOX emissions were maintained at a level parallel with diesel. The results indicated that the technique involving a high EGR rate and the addition of 25 ppm and 40 ppm of TiO2 nanoparticles to the C20D exhibits better reductions in NOX emissions by 17.34% and 21.83%, respectively, compared to the technique comprising the use of C20D + TiO2 and C20D. The reduction in the total concentration of PM via the addition of TiO2 nanoparticles to the C20D was 26.74% greater than neat C20D and diesel. In contrast, the incorporation of a high rate of EGR with C20D +TiO2 increased the PM concentrations by 16.85% compared to the technique without EGR. Furthermore, the high concentrations of TiO2 nanoparticles (40 ppm) in the C20D produced 19 nm smaller soot nanoparticles compared to the 23 nm larger soot nanoparticles produced from the low concentrations of TiO2 nanoparticles (25 ppm) added into the C20D. The current investigation reveals that the reduction in NOX emissions and the production of soot nanoparticles notably improved due to the synergic effect of EGR, the TiO2 nanoparticles, and biodiesel. [ABSTRACT FROM AUTHOR]

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 x ) emission. Technical solutions applied to bring main engines into compliance with current NO x 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.