Performance Of Combustion Engines Research Articles

Effects of different gas energy shares on combustion and emission characteristics of compression ignition engine fueled with dual-fossil fuel and dual-biofuel

This study systematically investigates the energetic and environmental performance of a four-cylinder compression ignition (CI) engine fueled by gaseous and liquid dual-fuel (D-F), utilising various combinations of fossil fuels and biofuels. Fossil diesel or pure hydrotreated vegetable oil (HVO) – new generation biodiesel was used as the pilot fuel to initiate ignition of the gaseous fuel. The gaseous fuels used were natural gas (NG) and simulated biogas (BG) composed of 60 % NG and 40 % CO2 by volume, injected into the intake manifold at varying gas energy shares (GES) of 40 %, 60 %, and 80 %. Reference values were provided from conventional combustion of diesel fuel and HVO. This study used numerical simulations to examine indicators of combustion, such as ignition delay, premixed combustion phase, diffusion combustion phase, and subsequent combustion phases, across diverse fuel combinations. Within lean dual-fuel mixtures, when the gaseous fuel remained below the flammability threshold, the peak pressure was diminished, the rate of pressure rise was lowered, and the combustion process decelerated, facilitating a faster transition to the diffusion phase. As the engine load and GES increased, the excess air ratio decreased, bringing the air-fuel mixture closer to the flammability limit, which in turn altered the combustion characteristics and engine performance trends. Combustion with increasing BG content showed partial similarities to that of NG, though the high CO2 content in biogas was found to suppress combustion, functioning similarly to an exhaust gas recirculation. The study also compared brake thermal efficiency (BTE), as well as specific emissions of CO, HC, NOX, CO2, and smoke for the D-F engine operation against pure diesel and HVO at different loads and GES levels. Additionally, an overlimit function was used to assess the emission levels of D-F engines with reference to emission limits.

Organic Rankine Cycle System Design by Utilizing The Waste Heat of Internal Combustion Engine Based on Numerical Simulation

Abstract Most of the energy supply for today’s human activities still comes from fossil energy. Energy based on fossil fuels can cause an increase in greenhouse gas (GHG) emissions. Therefore, increasing the efficiency of energy conversion systems based on fossil fuels is necessary to mitigate pollutant emissions. The internal combustion engine (ICE) is one energy conversion machine that still consumes fossil energy to work in the transportation sector. Losses during internal combustion engine operation result in reduced engine thermal efficiency. Exhaust gas heat loss is one of the relatively significant losses. It leads to the waste of heat, which could be utilized and converted into valuable energy in the form of electrical energy that the engine can use, resulting in a considerable amount of primary fuel that could be saved. An organic Rankine cycle (ORC) system is considered in this analysis as a heat recovery unit from the Diesel ICE. The Aspen Plus simulation software was chosen to design the system consisting of an ORC unit integrated with a Diesel ICE unit. The working fluid for ORC used in this analysis is R-141B, R-123, and R-245fa. The simulation results show that the heat the ORC unit receives from the ICE via turbocharger is around 366 °C. Thus, the system has a thermal efficiency of 11.11% when using R-141B as the working fluid, 8.41% if R-123 as the working fluid, and 6.63% when using R-245fa as the working fluid. This study also obtained a condenser design as part of the ORC unit. The condenser can be considered a plate heat exchanger, with 53 plates needed to support the process.

Effect of ignition timing on combustion characteristics and emissions of an X-type rotary engine with the high efficiency hybrid cycle

X-type rotary engines (XREs), using the high efficiency hybrid cycle, possess advantages of simple structure, high power-to-weight ratio, and high theoretical efficiency, making XREs as potential power sources in hybrid vehicles and small unmanned aerial vehicles. Typically, ignition timing has a promising potential to improve the combustion performance of spark ignition engines. In this work, the effects of ignition timing on flame propagation, combustion characteristics, and pollutants formation were studied adopting a three-dimensional simulation method. The results showed that at different engine speeds, significantly different flow forms and flow velocities in the larger chamber recess of the XRE were formed, resulting in large differences in flame propagation velocities at leading side and trailing side of the combustion chamber. Advancing ignition timing increased the flame propagation velocity at the given engine speed. Ignition timing had a more significant effect on peak pressure at medium-high speeds compared to low engine speeds. At 3000 RPM and 5000 RPM, the peak pressure was increased significantly with advancing ignition timing, but when ignition timing was advanced to -30 °CA, the increment in the in-housing pressure was minimal. As ignition timing was retarded, the ignition delay was slowly reduced. The effect of ignition timing on ignition delay was more significant for low speeds than for medium-high speeds. However, the influence of ignition timing on combustion duration showed the opposite trend. Delayed ignition showed a slight increase in indicated thermal efficiency and indicated mean effective pressure at low speeds, while the opposite was true at medium-high speeds. Nevertheless, the effect of ignition timing and engine speed on indicated specific fuel consumption is opposite to the trend of the above laws. With the increase of ignition timing, the NOx mass fraction first increased and then decreased at low speeds, with the maximum occurred at -30 °CA, but the NOx mass fraction continued to increase at high speeds. Soot and CO productions were slightly affected by ignition timing. To sum up, this XRE, setting the ignition timing of -30 °CA, achieved better flame propagation and engine performance at the price of a smaller increment of NOx emissions.

Impact of Soybean Biodiesel Blends with Mixed Graphene Nanoparticles on Compression Ignition Engine Performance and Emission: An Experimental and ANN Analysis

The extensive use of fuels in power generation plants, industries, and transportation has led to a scarcity of fossil fuels and has contributed to global warming. This has prompted researchers to focus on improving internal combustion engine performance, as the transportation system accounts for 50% of global fuel consumption. Soybean biodiesel plays a vital role in reducing emissions and fuel consumption in engines. In the current work, a blend of soybean oil is used as a biodiesel (B20, B40, and B60), with and without the addition of graphene nanoplatelets (GNPs) examined on a constant-speed compression ignition (CI) engine with respect to pure diesel. The blends are denoted as B20GNP10, B20GNP20, B20GNP40, B20GNP60, B20GNP80, and B20GNP100, according to their proposition of biodiesel and graphene nanoplatelets. Similar blends were prepared for B40 and B60 combinations with similar GNPs concentrations. The prepared blend properties were measured, and good thermophysical properties were found. The trial includes testing the engine emissions and performance at altering loads ranging from 0 to 12 kg for all blends. The artificial neural network (ANN) tool is used to forecast the accuracy of experimental results. Compared to pure diesel, the B60GNP100 blend at 12 kg load condition showed the lowest brake specific fuel consumption at 12.58 % and the highest brake thermal efficiency at 27.13%. Emissions were estimated using a gas analyzer, and the outcomes indicated that the biodiesel blends have controlled levels of CO, CO2, NOx, and HC compared to pure diesel. The ANN model with 99.99% accuracy was developed using experimental data, confirming the accuracy of the experimental results with lower simulation time and cost. Additionally, the B60GNP100 blend yielded better results compared to previous studies.

Effects of alcohol fuels on SACI engine and analyze of prediction of SACI engine performance by artificial neural networks

The combustion characteristics of spark assistant compression ignition mode under different loads and fuels were explored, as well as by constructing artificial neural networks(ANN) model, the prediction ability of different algorithms for engine performance was discussed. Burning methanol and n-butanol can help to improve IMEP and induce earlier spontaneous combustion. The knock intensity(KI) of engine fueled with methanol was highest followed by n-butanol and gasoline, but maximum amplitude of filtered pressure oscillation(MAPO) shows the opposite trend. KI showed great positive liner correlation with ignition timing. Methanol showed the most outstanding tolerance on the compression ignition state. Fueled with methanol can decreased equivalent brake specific fuel consumption(ESFC) up to 52.9 % compared with the initial SI gasoline engine. N-butanol can improve BSNOx, BSTHC and BSCO concurrently, however fueled with methanol will worsen BSNOx. ANN model for engine combustion, economy and emissions performance was built. The prediction accuracy of Bayesian regularization algorithm for engine performance predicting was highest, but it have no advantage in the calculating times when the amount of data was large while the Levenberg-Marquardt algorithm would be the ideal efficient. The mean square error of ESFC and emissions parameters under scaled conjugate gradients algorithm always poorest.

Diesel Engine Turbocharger Monitoring by Processing Accelerometric Signals through Empirical Mode Decomposition and Independent Component Analysis

In this study, a method for the monitoring of internal combustion engine operation by vibration signals is proposed. The work falls within the context of the increasingly stringent standards relating to the environmental impact of engines and the development of monitoring and control techniques to ensure increased engine performance as well as fuel saving and reduction of pollutant emissions. Experimentation was performed on a turbocharged light-duty compression ignition direct-injection engine. Two monoaxial accelerometers were installed on the engine compressor case, the speed of which has been demonstrated to be closely related to the engine operation. Vibration measurements of the engine compressor case have been processed by combining the Empirical Mode Decomposition technique with Independent Component Analysis and Short Time Fourier Transform to indirectly estimate the turbocharger speed. The obtained traces have been compared to the direct turbocharger velocity measures during the stationary running of the engine (speed and load conditions varied in the complete engine’s range of operation). The results point out the potentiality of the methodology in algorithms devoted to identifying modifications of the combustion development regarding regular operation via indirect turbocharger speed monitoring.

Unveiling the impact of date-specific analytics on vehicle fuel consumption and emissions: A case study of Shiraz city

Understanding the factors affecting internal combustion engine performance is crucial for improving emissions and fuel efficiency in real traffic. This paper investigates the influence of date-specific factors, such as working days and holidays on fuel consumption and emissions of a representative internal combustion engine in the context of Shiraz city. The data was collected by measuring the speed of vehicle on a specific route during peak traffic times on both working days and holidays. The determined route was calculated by a qualitative and quantitative method. K-means clustering and principal component analysis are employed to design representative driving cycles, then combining micro-trips and smoothing them to develop driving cycles. Characteristics of both driving cycles, emissions such as HC, NOx, CO, and fuel consumption were specified under a simulated vehicle model of Peugeot 206 and placed through both real driving cycles by using advanced vehicle simulation software. It has been observed that variations in fuel consumption and emissions between holidays and working days can be attributed to distinct driving patterns and characteristic parameters, such as acceleration, speed, and driving time. Contrary to common assumptions, the study found that fuel consumption was approximately 8 % higher on holidays compared to working days, primarily due to increased driving time and higher average speeds. Moreover, higher acceleration and speed on holidays led to a significant increase in CO emissions (about 36 %) and NOx emissions (about 4 %) compared to working days. However, HC emissions was found to be 27.03 % higher on working days according to lower speed. This study helps in reducing fuel consumption and emissions by uncovering internal combustion engine factors, optimizing driving patterns, and promoting sustainable transport on working days and holidays.

A comprehensive experimental and theoretical study of thermal response mechanisms of TKX-50 and HMX

TKX-50 and HMX, as two highly promising energetic materials, are widely used in rocket propellants. TKX-50/HMX cocrystal can also improve the defects of TKX-50 and HMX and vastly expand their application scope. Their response mechanisms to the same thermal stimulation, including reactivity and decomposition and combustion behavior, are important in understanding their combustion characteristics and engine performance. This study systematically investigates the thermal response mechanisms of TKX-50 and HMX under the same thermal stimulations based on experimental measurements and theoretical analysis. Ignition delay times and burn times of TKX-50 and HMX with different particle sizes at various temperatures and pressures are measured in shock tube experiments. ReaxFF MD simulations are performed to analyze the thermal decomposition of TKX-50 and HMX in terms of potential energy evolution, intermediate and final products, and possible reaction pathways. Ab initio kinetics of hydrogen atom abstraction reactions of TKX-50 and HMX with three highly active species, Ḣ, ȮH, and NO2, are studied. The barrier heights, reaction enthalpies and rate coefficients for all reactions are further analyzed. The results show that: (1) the ignition delay time and burn time of TKX-50 (128, 138, and 55 µm) are measured to be 200–600 µs and 40–400 µs respectively, which are almost the same as those of HMX (6 and 0.8 µm) in the same temperature range; (2) the burn time of TKX-50 is less affected by pressure but more affected by particle size, whereas both pressure and particle size have a significant effect on the burn time of HMX; (3) TKX-50 is shown to be readily decomposed and less affected by temperature changes than HMX under the same conditions; (4) ȮH is generated more rapidly in the TKX-50 system, but more persistently in the HMX system; (5) H atom abstraction reactions from TKX-50 by all species are less endothermic but more exothermic than those from HMX.

The Influence of Pre-Chamber Parameters on the Performance of a Two-Stroke Marine Dual-Fuel Low-Speed Engine

With increasing environmental pollution from ship exhaust emissions and increasingly stringent International Maritime Organization carbon regulations, there is a growing demand for cleaner and lower-carbon fuels and near-zero-emission marine engines worldwide. Liquefied natural gas is a low-carbon fuel, and when liquefied natural gas (LNG) is used on ships, dual-fuel methods are often used. The pre-chamber plays a key role in the working process of dual-fuel engines. In this paper, an effective three-dimensional simulation model based on the actual operating conditions and structural characteristics of a marine low-pressure dual-fuel engine is established. In addition, the effects of changing the Precombustion chamber (PCC) volume ratio and the PCC orifice diameter ratio on the mixture composition, engine combustion performance, and pollutant generation were thoroughly investigated. It was found that a small PPC volume ratio resulted in a higher flame jet velocity, a shorter stagnation period, and an acceleration of the combustion process in the main combustion chamber. When the PCC volume was large, the Nitrogen oxygen (NOx) ratio emission was elevated. Moreover, the angle of the PCC orifice affected the flame propagation direction of the pilot fuel. Optimizing the angle of the PCC orifice can improve combustion efficiency and reduce the generation of NOx. Furthermore, reasonable arrangement of the PCC structure can improve the stability of ignition performance and accelerate the flame jet velocity.

Study on the integration of hydrogen in a multi-cylinder low heat rejection diesel engine using a ternary blend

Among alternative fuels, hydrogen (H2) holds significant promise as both a fuel and an energy carrier. It is expected to become a key alternative fuel in the near future to meet stringent pollution standards. H2 is used in internal combustion (IC) engines, gas turbines, and the aerospace industry due to its non-toxic and odorless nature, high calorific value (CV), and wide temperature range of combustibility. Additionally, it is a long-term renewable energy source that produces fewer pollutants. This study explores the impact of different H2 ratios on combustion behavior, engine performance, and emission characteristics in a dual-fuel compression ignition (CI) diesel engine. The current research focuses on the effect of TB of ethanol, Jatropha methyl ester, and diesel with the induction of H2 with different flow rates in diesel engine in dual fuel mode (DFM). The tests were performed at different engine loads, 25%, 50%, 75%, and 100% at a constant engine speed of 2500 rpm. H2 is inducted at different flow rates like 2, 4, and 6 Litres per minute (lpm). Partially stabilized zirconia (PSZ) is used to coat the cylinder head, piston crown, and valves with a thickness of 0.5 mm. The combined effect of TB fuel and H2 in a CI engine improves combustion and engine performance. At full load condition, brake thermal efficiency (BTE) is improved by 11.5% for TB fuel with H2 at 6 lpm, and exhaust gas temperature (EGT) increased by 12.7%. The cylinder pressure (CP) and heat release rate (HRR) are increased by 7.5% and 10.6% at TB fuel with 6 lpm of H2 induction. The utilization of H2 as an alternative energy source has significant consequences for the future of green energy production.

Effects of using nanosecond repetitively pulsed discharge and turbulent jet ignition on internal combustion engine performance

Robust ignition of hard-to-ignite fuels is essential for future spark ignited internal combustion engines, particularly for introducing efficiency-enhancing diesel-like process parameters like air excess or high amounts of exhaust gas recirculation (EGR). On the one hand, novel plasma-based ignition systems like Nanosecond Repetitively Pulsed Discharge (NRPD) are promising in extending the ignition limits and the early flame development speed. On the other hand, Turbulent Jet Ignition is effective for shortening the combustion duration and decreasing the unburned hydrocarbon emissions.This article investigates experimentally the combination of NRPD ignition and TJI. The aim is to use a technology for robust inflammation (NRPD) in combination with a technology for fast combustion of the bulk charge (TJI). For this purpose, a turbocharged light-duty four-cylinder engine operated with natural gas is used. The engine can be fitted with a classical Open Chamber (OC) spark plug or with Pre-Chambers (PC). The PCs can be filled uniquely with fuel and air coming from the Main Chamber (MC) (“passive PC”), or additional fuel can be added to the PCs (“active PC”). The air-to-fuel ratio and EGR rate can be freely controlled. Five different combustion strategies are investigated with NRPD ignition and compared against an inductive discharge ignition system. The combustion strategies are passive PC with air and EGR dilution, active PC with air dilution, and Open Chamber (OC) with air and EGR dilution. HRR evaluations and a loss analyses are performed to interpret the results.Despite the faster inflammation present with NRPD ignition, similar peak efficiencies and emissions are reached in OC configuration using the inductive discharge and NRPD ignition systems, which are achieved by varying air-to-fuel ratios (AFR) and EGR rates. Above dilution levels for peak efficiency, the efficiency using NRPD ignition decreases at a slower pace and tolerates higher AFR and EGR rates, thanks to a more complete and shorter combustion.For the PC experiments using NRPD ignition, an efficiency increases and a reduction of emissions compared to inductive discharge ignition are present for the investigated AFR and EGR rates for both active and passive PC operations. The efficiency increase is present due to a stronger pre-chamber discharge and thanks to a faster end phase of combustion. Actively fueling the PC results in faster and more complete combustion that is overcompensated by the increased wall heat losses, reducing the overall efficiency. The results show that passive PC with NRPD ignition may be an ideal ignition concept that maximizes engine efficiency and minimizes emissions.

The impact of scavenging air state on the combustion and emission performance of marine two-stroke dual-fuel engine

The scavenging process significantly affects the combustion and emission performance of marine low-speed two-stroke dual-fuel engines. Optimizing scavenging air pressure and temperature can enhance the engine's combustion efficiency and emission control performance, thereby achieving more environmentally friendly and efficient operation of dual-fuel engines. This study focuses on marine low-speed two-stroke dual-fuel engines, analyzing the effects of scavenging air pressure (3.0 bar, 3.25 bar, 3.5 bar, and 3.75 bar) and scavenging air temperature (293 K, 303 K, and 313 K) on engine performance and emission products. The results indicate that scavenging air pressure has a greater impact on engine performance than scavenging air temperature. An increase in scavenging air pressure leads to higher thermal efficiency and power. As the scavenging air pressure increases from 3 to 3.75 bar, the indicated thermal efficiency (ITE) increases from 44.02 to 53.26%, and indicated mean effective pressure (IMEP) increases by approximately 0.35 MPa. Increased scavenging air pressure improves nitrogen oxide (NOx) and hydrocarbons (HC) emissions. For every 0.25 bar increase in scavenging air pressure, NOx emissions decrease by 3.53%, HC emissions decrease by 33.35%, while carbon dioxide (CO2) emissions increase by 0.71%. An increase in scavenging air temperature leads to lower ITE and IMEP. As the air temperature changes from 293 to 313 K, the ITE decreases by approximately 1%, and IMEP decreases by about 0.04 MPa. Increased scavenging air temperature improves CO2 emissions. For every 10 K increase in the air temperature, the CO2 emissions decrease by 0.02%, while NOx emissions increase by 4.84%, HC emissions increase by 34.39%. Therefore, controlling scavenging air pressure is more important than scavenging air temperature in the operational management of marine two-stroke engines. Higher power and lower NOx and HC emissions can be achieved by increasing the scavenging air pressure.

Integrated catalytic systems for simultaneous NOx and PM reduction: a comprehensive evaluation of synergistic performance and combustion waste energy utilization.

The global transition towards sustainable automotive vehicles has driven the demand for energy-efficient internal combustion engines with advanced aftertreatment systems capable of reducing nitrogen oxides (NOx) and particulate matter (PM) emissions. This comprehensive review explores the latest advancements in aftertreatment technologies, focusing on the synergistic integration of in-cylinder combustion strategies, such as low-temperature combustion (LTC), with post-combustion purification systems. Selective catalytic reduction (SCR), lean NOx traps (LNT), and diesel particulate filters (DPF) are critically examined, highlighting novel catalyst formulations and system configurations that enhance low-temperature performance and durability. The review also investigates the potential of energy conversion and recovery techniques, including thermoelectric generators and organic Rankine cycles, to harness waste heat from the exhaust and improve overall system efficiency. By analyzing the complex interactions between engine operating parameters, combustion kinetics, and emission formation, this study provides valuable insights into the optimization of integrated LTC-aftertreatment systems. Furthermore, the review emphasizes the importance of considering real-world driving conditions and transient operation in the development and evaluation of these technologies. The findings presented in this article lay the foundation for future research efforts aimed at overcoming the limitations of current aftertreatment systems and achieving superior emission reduction performance in advanced combustion engines, ultimately contributing to the development of sustainable and efficient automotive technologies.

Density-Gibbs energy correlation models for binary biofuel mixtures

The density of binary biofuel mixtures significantly influences fuel properties, directly affecting internal combustion engine performance. This research aims to develop correlational models to calculate densities in binary biofuel mixtures, leveraging the Gibbs energy mixing rule. Two correlation models are proposed: the ideal Gibbs energy mixing rule and the Gibbs energy quadratic mixing rule. These models aim to enhance the cross-interaction of Gibbs energy of activation (ΔG12) to improve predictive performance. Importantly, the constants of the existing models are directly related to thermodynamic parameters. To assess the accuracy of the models, observed densities were collected from four different binary systems: biodiesel + diesel, pure fatty acid ethyl ester + alcohol, biodiesel + alcohol, and alcohol binary mixtures, amounting to 2242 data points obtained from the literature. Based on mole fractions, both models were compared to earlier approaches. The examination revealed that the equation formulated by the quadratic mixing rule exhibited heightened precision and efficacy. Our data demonstrate that the extended ΔG12 provided the most accurate results.

Investigation of the Effect of TiO2 Nanoparticles on Engine Performance and Emission Characteristics in Diesel Engines

This study aimed to examine the changes in performance and emission values in a four-stroke and three-cylinder diesel engine by using pure diesel fuel and fuels created by adding TiO2 nanoparticles. Adding TiO2 nanoparticles to the fuel aimed to improve the combustion characteristics of the diesel engine and reduce the harmful effects of exhaust emissions. Pure diesel and TiO2 nanoparticle added fuel samples in three distinct amounts, 25 ppm, 50 ppm, and 75 ppm, were prepared in magnetic and ultrasonic mixers as D100, D100+25TiO2, D100+50TiO2, and D100+75TiO2. All fuel samples used in the research were tested at a constant speed of 1800 revolutions per minute (rpm) at 25%, 50%, 75%, and 100% full loads. When TiO2-added fuels were compared to pure diesel, there was a 15.12% rise in brake thermal efficiency at %25 load and a 13.36% drop in brake specification fuel consumption at %25 load. EGT values also increased with the increase in load and adding TİO2. The amount of CO2 in exhaust emissions increased by 5% at maximum load in the fuel with the highest TiO2 additive according to neat diesel. There was an average increase of 11.44% in NOX emissions for all loads with TiO2 addition. The results show that the fuel mixture created by adding TiO2 nanoparticles can be used in certain proportions in diesel engines and that the TiO2 addition positively improves the combustion properties, engine performance, and exhaust gas emissions.

Towards optimized excess air ratio and substitution rate for a dual fuel HPDI engine

The diesel-piloted high-pressure direct-injection (HPDI) natural gas engine is a significant application of natural gas in heavy-duty engines. However, there is limited research focusing on quantitative optimization of the excess air coefficient and natural gas substitution rate of HPDI engines. In order to support the design and development of HPDI engines, this article investigates the effects of excess air coefficient and substitution rate on a dual fuel HPDI engine combustion performance and emission characteristics. Results show that increasing the excess air coefficient results in higher cylinder pressure, but it has minimal effect on the heat release rate. A higher excess air coefficient can also lead to higher nitrogen oxides (NOx) emissions, lower soot emissions, methane (CH4) and total hydrocarbon (THC) emissions significantly decrease at 50% loads (Case2 and Case4), but these increase at 70% loads (Case1 and Case3). Furthermore, increasing the substitution rate markedly reduces greenhouse gas emissions, though it comes with the drawback of heightened combustion instability, and there is a trade-off between engine combustion cycle variations and greenhouse gas emissions as the substitution rate changes. The above research findings will provide optimization guidance for the engineering development of HPDI engines.

Influence of hydrogen-assisted combustion in compression ignition engines fueled with fuel blends of pine oil and waste cooking oil biodiesel using toroidal combustion chamber

In this research study, fuel blends of pine oil and waste cooking oil biodiesel (P/WCO) were examined for combustion analysis, engine performance, and emission characteristics tests. Improved combustion and engine performance were achieved using a toroidal re-entrant combustion chamber (TCC) and hydrogen supply as a dual fuel. The combustion behavior of fuel blends and hydrogen fuel was examined by varying the engine load at a constant speed. The results revealed that significant reduction in the specific fuel consumption for rich pine oil. Thus, a slightly lesser energy share from the fuel blends and a higher energy share from the hydrogen fuel was required for the engine to maintain the same brake power. Lower viscosity, higher flash point, and presence of oxygen in the pine oil enhance the combustion rate and brake thermal efficiency. Furthermore, hydrogen induction in the engine improves the flame velocity. A lesser crevice volume in the TCC can trap the unburnt fuel which can further increase the combustion efficiency. Thus, rich pine oil with the support of hydrogen induction in TCC causes advanced ignition, improved combustion, and more heat release during the combustion. The investigation results revealed that hydrogen induction increases the heat release rate and peak pressure by 7.4% and 2.67%, respectively. Similarly, the maximum of 24.55% increase in BTE and 18.22% reduction in BSFC was observed due to a constant 10 lpm hydrogen induction. Furthermore, hydrogen fuel significantly reduces the emissions such as CO, HC, CO2, and smoke. However, more NOx was generated due to more heat release rate during combustion. Thus, pine oil and waste cooking oil biodiesel blends with the support of hydrogen induction in TCC improve the engine performance and mitigate the toxic pollutants and can be a suitable alternative to diesel fuel.

Implementation of various injection rate shapes in an ammonia/diesel dual-fuel engine with special emphasis on combustion and emissions characteristics

As the problem of global warming continues to intensify, carbon-free fuel ammonia is crucial for internal combustion engines, and a potential ammonia combustion route is dual-fuel mode. The impact of various injection rate shapes (trapezoid, wedge, slope, triangle, and rectangle) on engine combustion and emissions performance with 0 %, 20 %, and 40 % ammonia energy fractions were estimated. Under the identical ratio of the ammonia-doped schemes, the fuel injection gross mass and fuel injection duration are the same. The results indicate that the triangle injection rate shape can make the mixture of diesel and ammonia gas more uniform, leading to combustion in the combustion chamber closer to homogeneous combustion. When the injection shape is the triangle, the indicated mean effective pressure in the cylinder is the highest at 10.29 bar, which is 4.04 % higher than that of the pure diesel original injection shape. The triangle injection shape makes the ammonia-diesel dual fuel burn more concentrated, resulting in lower unburned ammonia loss and higher thermal efficiency. Under the 40 % ammonia energy fraction and triangle injection shape, the highest thermal efficiency reaches 40.57 %, 1.58 % higher than the pure diesel original injection shape. Additionally, it significantly reduces unburned ammonia emissions. The injection rate shapes have a minor impact on CO2 emissions. The rapid increase in-cylinder average temperature can substantially reduce N2O emissions, thereby lowering total greenhouse gas emissions. Among them, the total greenhouse gas emissions of 40 % ammonia energy fraction and triangle injection shape are the lowest, at 81619 ppm, which is 11.3 % lower than that of pure diesel original injection shape. On the contrary, it will increase NOx emissions. Conversely, the slopes exhibit the lowest NOx emissions at 220.8 ppm, representing an 88 % reduction compared to the pure diesel original injection shape.

Impact of ammonia energy fraction on improving thermal efficiency and emissions of ammonia/biodiesel in dual fuel diesel engine

Ammonia (NH3) and Cashew Nut Shell Oil (CNSO) biodiesel blends are used in a four-stroke, single-cylinder Internal Combustion (IC) engine to examine combustion characteristics, engine performance, and emissions. NH3 is an encouraging alternative fuel, considering its high energy density and carbon neutrality. Biodiesel derived from cashew nut shells is an environmentally friendly fuel option with substantial unsaturated fatty acid content. An investigation was executed with NH3 at a flow rate of 3 and 6 liters per minute (LPM) at 50 % CNSO, 50 % diesel (50CNSO50D), and 100 % CNSO. With the addition of NH3 to diesel, peak in-cylinder pressures increased from 63.412 bar to 68.87 bar at 3 LPM and 70.239 bar at 6 LPM, respectively. In comparison to diesel, CNSO biodiesel exhibited a minor decrease in peak pressure (62.034 bar) and a slight delay in ignition. Compared to diesel, thermal efficiency increased significantly with NH3, rising from 31.1 % to 33.3 % and 34.8 % at 3 and 6 LPM NH3, respectively.CO emissions analysis revealed that CNSO biodiesel reduced emissions to 17 g/kWh, comparatively diesel's 19 g/kWh, with NH3 further reducing them. The NOx emissions from CNSO biodiesel blends are higher (16 g/kWh for CNSO) than diesel (13 g/kWh), but the addition of NH3 reduces NOx emissions across all fuels. The low energy content of CNSO leads to higher CO2 emissions, but NH3 reduces these emissions. CNSO and NH3 blends had lower hydrocarbon (HC) emissions than diesel. It has been found that using NH3 and CNSO biodiesel improves the performance of diesel engines and reduces emissions, contributing to the reduction of global emissions and helping to create a more sustainable future.

Effects of the fuel blend flow rate on engine combustion performance

Effects of the fuel blend flow rate on engine combustion performance