Homogeneous Charge Research Articles

Gaussian-Transform for the Dirac Wave Function and its Application to the Multicenter Molecular Integral Over Dirac Wave Functions for Solving the Molecular Matrix Dirac Equation

Gaussian-transform formula is derived for the Dirac wave function. Using it, one can derive the multicenter molecular integral over Dirac wave functions for any physical quantity. As the first application of it, multicenter molecular integrals over Dirac wave functions are derived for the homogeneous charge density distribution model and the Gauss-type charge density distribution model. Such integrals are necessary for solving the gauge-invariant molecular matrix Dirac equation with using the restricted magnetic balance.

Surface Planarization-Epitaxial Growth Enables Uniform 2D/3D Heterojunctions for Efficient and Stable Perovskite Solar Modules.

Two-dimensional/three-dimensional (2D/3D) halide perovskite heterojunctions are widely used to improve the efficiency and stability of perovskite solar cells. However, interfacial defects between the 2D and 3D perovskites and the poor coverage of the 2D capping layer still hinder long-term stability and homogeneous charge extraction. Herein, a surface planarization strategy on 3D perovskite is developed that enables an epitaxial growth of uniform 2D/3D perovskite heterojunction via a vapor-assisted process. The homogeneous charge extraction and suppression of interfacial nonradiative recombination is achieved by forming a uniform 2D/3D interface. As a result, a stabilized power output efficiency of 25.97% is achieved by using a 3D perovskite composition with a bandgap of 1.55eV. To demonstrate the universality of the strategy applied for different perovskites, the champion device based on a 1.57eV bandgap 3D perovskite results in an efficiency of 25.31% with a record fill factor of 87.6%. Additionally, perovskite solar modules achieve a designated area (24.04 cm2) certified efficiency of 20.75% with a high fill factor of 80.0%. Importantly, the encapsulated uniform 2D/3D modules retain 96.9% of the initial efficiency after 1246h operational tracking under 65 °C (ISOS-L-3 protocol) and 91.1% after 862h under the ISOS-O-1 protocol.

Natural gas-fueled HCCI engine performance and emission analysis and comparison with SI and spark-assisted operations

ABSTRACT The homogeneous charge compression ignition (HCCI) engine is a promising technology in terms of both soot and NOx emission. Natural gas (NG) is advantageous especially for HCCI engines with its single stage combustion, low C/H ratio, and high octane number. Since the main challenge of HCCI technology is stability and transient operations, using HCCI for constant speed operations may be advantageous. In this study, a CI diesel engine, which is used as a generator at constant speed, was modified and converted into an NG-fuelled, SI engine. Then, the engine was supplied with NG for SI, HCCI, and spark-assisted HCCI experiments. Spark-assisted operations were executed by using 3, 5, and 7 degree ignition advance values to assist HCCI combustion. In-cylinder pressure variations, exhaust temperature, specific fuel consumption, and emission values were investigated for comparison of different strategies. Experimental results showed that using the HCCI strategy and retardation of ignition advance of spark-assisted HCCI operations reduced maximum pressure. Therefore, these strategies improved NOx emissions, while HC emissions were slightly increased. The spark-assisted HCCI strategy improves the stability of operation while increasing CO emission. The specific fuel consumption value of HCCI was slightly higher than that of SI operation, while it was lower than spark-assisted strategies.

Adoptability assessment of HCDI and RCCI modes in plug-in parallel hybrid electric vehicles using sustainable fuels and model-based torque structure calibration strategies

In this research, a comparative analysis of plug-in hybrid electric vehicle (PHEV) engine was conducted with two advanced low temperature combustion (LTC) techniques viz. Homogeneous charge with direct injection (HCDI) and reactivity-controlled compression ignition (RCCI), utilizing alternative fuels diethyl ether (DEE) and ethanol. This was attempted to exhibit the promising potential of LTC based PHEV to achieve the highest efficiency and low emissions. The experimental results disclosed that DEE powered HCDI can achieve superior thermal efficiency with an impressive peak torque of 14 Nm. On the other hand, ethanol powered RCCI produced a peak torque of 17.5 Nm with remarkable emission reduction characteristics, especially CO2. It was vindicated that HCDI-PHEV outperformed the RCCI-PHEV in terms of fuel economy despite both HCDI and RCCI being lower than the conventional diesel PHEV. The NOx emissions from HCDI were almost negligible. About 20 % lower nitrogen oxide (NOx) emissions were recorded for RCCI respectively as compared to diesel (36 g/s). HCDI and RCCI showcased about 2 and 1.3 times higher soot emissions than diesel (7.12 g/s). Fuel economy was improved by 15 % and 43 % respectively under HCDI and RCCI modes over the conventional diesel mode of PHEV operation. When the PHEV was operated continuously for about 3.5 h, the battery's SOC dropped from 80 % to 45 % under diesel operation, whereas it only reached 50 % and 60 % under RCCI and HCDI mode operation. Low fuel consumption characteristics, acceptable torque production capabilities and ultralow NOx reduction potential established HCDI as the preferable choice for PHEV over RCCI.

Exergetic investigation of the influence of injector location in HCCI engines utilizing DEE as pilot fuel and biogas as primary fuel

To address the global demand for sustainable energy, integrating biogas into internal combustion engines is becoming more important. Homogeneous Charge Compression Ignition (HCCI) engines, known for high efficiency and low emissions, offer a promising solution. This study investigates the optimal injector location for using biogas in HCCI engines, with diethyl ether (DEE) as the pilot fuel, evaluating three positions: (i) at the port, (ii) 6 cm away (Manifold 1), and (iii) 10 cm away (Manifold 2). Through experiments and simulations, the impact of injector location on engine performance is analyzed across various parameters, including methane fractions, engine loads, and exhaust gas compositions. Results show that port injection achieves the highest first law and exergy efficiencies but increases emissions of hydrocarbons (HC), carbon monoxide (CO), and smoke. At 15 Nm load, Manifold 1 shows a 27.34 % reduction in exergy efficiency compared to port injection, while Manifold 2 exhibits an 18.49 % decrease at higher loads. Despite lower efficiencies, Manifold 1 effectively reduces harmful emissions. The study also considers exergo-economic and sustainability aspects, highlighting that while port injection is optimal for efficiency, Manifold 1 excels in minimizing HC and CO emissions, with a 50 % reduction in HC and 71.43 % reduction in CO emissions at 15 Nm load compared to port injection. Manifold 2 achieves the lowest smoke emissions across all loads. This investigation provides crucial insights into optimizing HCCI engines for biogas utilization, emphasizing injector location, fuel composition, and operating parameters to enhance performance and reduce environmental impact.

Performance of a Methanol-Fueled Direct-Injection Compression-Ignition Heavy-Duty Engine under Low-Temperature Combustion Conditions

Low-temperature combustion (LTC) concepts, such as homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC), aim to reduce in-cylinder temperatures in internal combustion engines, thereby lowering emissions of nitrogen oxides (NOx) and soot. These LTC concepts are particularly attractive for decarbonizing conventional diesel engines using renewable fuels such as methanol. This paper uses numerical simulations and a finite-rate chemistry model to investigate the combustion and emission processes in LTC engines operating with pure methanol. The aim is to gain a deeper understanding of the physical and chemical processes in the engine and to identify optimal engine operation in terms of efficiency and emissions. The simulations replicated the experimentally observed trends for CO, unburned hydrocarbons (UHCs), and NOx emissions, the required intake temperature to achieve consistent combustion phasing at different injection timings, and the distinctively different combustion heat release processes at various injection timings. It was found that the HCCI mode of engine operation required a higher intake temperature than PPC operation due to methanol’s low ignition temperature in fuel-richer mixtures. In the HCCI mode, the engine exhibited ultra-low NOx emissions but higher emissions of UHC and CO, along with lower combustion efficiency compared to the PPC mode. This was attributed to poor combustion efficiency in the near-wall regions and engine crevices. Low emissions and high combustion efficiency are achievable in PPC modes with a start of injection around a crank angle of 30° before the top dead center. The fundamental mechanism behind the engine performance is analyzed.

Erratum: Experimental Study on the Diesel Injection Pressure of Homogeneous Charge Induced Ignition for Multi-cylinder Operation

Erratum: Experimental Study on the Diesel Injection Pressure of Homogeneous Charge Induced Ignition for Multi-cylinder Operation

Combustion Test for the Smallest Reciprocating Piston Internal Combustion Engine with HCCI on the Millimeter Scale

Micro reciprocating piston internal combustion engines are potentially desirable for high-energy density micro power sources. However, complex subsystem functions hinder the downsizing of reciprocating piston internal combustion engines. The homogeneous charge compression-ignition (HCCI) combustion mode requires no external ignition system; it contributes to structural simplification of the reciprocating piston internal combustion engines under a micro space constraint but has not been adequately verified at the millimeter scale. The study used a millimeter-scale HCCI reciprocating piston internal combustion engine fueled by a mixture of kerosene, ether, castor oil, and isopropyl nitrate for combustion investigation. The test engine with a displacement of 0.547 cc is the smallest reciprocating piston internal combustion engine known to have undergone in-cylinder combustion diagnosis. It is observed that the HCCI combustion mode at the millimeter scale can realize stable combustion with excellent cooperation for the thermodynamic cycle under appropriate structural and operating conditions, which is essentially not inferior to those in conventional-sized reciprocating piston internal combustion engines. This finding helps the next step of scaling down reciprocating piston internal combustion engines.

From nickel–metal hydride batteries to advanced engines: A comprehensive review of hydrogen's role in the future energy landscape

Hydrogen has emerged as a disruptive force in the energy landscape, poised to revolutionise the automotive sector with its use in both fuel cell and internal combustion engines. This article covered two topics: application of metal hydrides for hydrogen storage and use of cutting-edge engine technology in hydrogen-powered vehicles. This article begins with discussing the different characteristics of materials that are used to store hydrogen. Metal hydrides, rare earth elements, and carbon-based compounds are among the materials that are carefully studied in this work. Understanding how effectively these materials can store hydrogen was another goal of this research. In order to fully utilize hydrogen's potential, it is imperative to compare them with conventional fossil fuels highlighting their significance. Additionally, this study explains how hydrogen can be used to power existing and newer automobile vehicles. Also discussed are the viability and potential mechanisms of operation for various hydrogen-using engine technologies, such as compression ignition and spark ignition engines. Cutting-edge on vehicles with fuel cell and engine technology powered by hydrogen along with their challenges are explained. They include discussions of several techniques such as homogenous charge compression ignition (HCCI), dual-fuel, and reactivity-controlled combustion ignition (RCCI). Additionally, the advantages and disadvantages of utilizing hydrogen in these state-of-the-art engine technologies are discussed. This research offers insights on the future of automobiles in addition to hydrogen storage. This study points the path towards a more creative and sustainable energy environment in which hydrogen plays a major role in the storage and utilization for automobile vehicles.

Effect of direct water injection timing and quantity on combustion, performance, and emission characteristics of a homogeneous charge compression ignition engine − A CFD analysis

Direct water injection in an HCCI engine is a promising strategy to extend the operating load limit. The advantage of water injection depends on the percentage of water evaporated inside the cylinder, which further depends on the time available for the evaporation and the interaction of water spray plumes with the in-cylinder air-flow field. Here, CFD investigations are done to find the effect of water injection timing (WIT) and quantity on the load limit and performance and emission characteristics of the HCCI engine. Various WITs are considered for the study, varying from 100° CA before TDC to 20° CA before TDC. The water-to-fuel ratio is varied from 0 to 1 in steps of 0.2. A three-dimensional computational fluid dynamics model is used for the study, and CFD models used are validated from the available experimental data in the literature. The results show that WITs before 650° CA and after 670° CA are inappropriate for the HCCI engine, as heat release rate and MRPR are high in these cases. Also, the evaporation rate of water increases when the water injection is done in the region where the direction of the air-flow field is opposite to the direction of water injection. At the WIT of 60°, the HRR and MRPR are minimal, and the water vapor distribution is good compared to other cases. Also, it is seen that a water-to-fuel ratio of 0.8 gives more scope for extending the upper load limit with a marginal penalty of the IMEP; hence, a WIT of 60° with the water-to-fuel ratio of 0.8 is considered optimum. With the optimum case, it is feasible to increase the ER from 0.74 to 0.95, resulting in an increase of IMEP from 3.23 bar to 4.92 bar, which is 52.3 % more than without a water injection case at the ER of 0.74. Also, it showed minimum NOx emissions in all the water injection cases. Hence, these results address the primary challenges associated with HCCI engines, demonstrating that direct water injection can substantially improve the combustion controllability and operational range of HCCI engines.

Computational analysis of ammonia-hydrogen blends in homogeneous charge compression ignition engine operation

Ammonia (NH3) is considered a promising alternative fuel due to its renewable and carbon-free nature. The addition of hydrogen (H2) significantly improves its flammability, making it suitable for use in internal combustion engines. The homogeneous charge compression ignition (HCCI) technique offers a practical solution for high-efficiency NH3-H2 operation, but it is not extensively discussed in existing literature. To enhance the understanding of NH3-H2 HCCI engines, this study employs a zero-dimensional model validated against experimental results to investigate engine efficiency and nitrogen oxides (NOx) emissions. The results indicate that an ammonia-dedicated HCCI mode would misfire at a 22:1 compression ratio and an engine speed of 1500 rpm if the intake pressure and temperature are insufficient. Hydrogen addition can help overcome the misfire issue and reduce the intake pressure and temperature required for combustion initiation. However, higher hydrogen addition ratios decrease thermal efficiency and increase NOx emission levels. In lean NH3-H2 HCCI operation, NOx emissions are primarily driven by fuel-borne mechanisms and peak at an equivalence ratio of around 0.5. A higher hydrogen addition ratio should be avoided as it increases the risk of ringing, thereby reducing the maximum allowable equivalence ratio and engine load. As a result, a moderate hydrogen addition ratio, such as 20 %, is preferable for NH3-H2 HCCI engines. Additionally, an equivalence ratio of approximately 0.3 is optimal, balancing multiple performance indicators such as thermal efficiency, NOx emission levels, and engine operating stability. These findings suggest that the operating range of NH3-H2 HCCI engines is limited, making them more suitable for off-road applications, such as power generation.

Controllability of Pre-Chamber Induced Homogeneous Charge Compression Ignition and Performance Comparison with Pre-Chamber Spark Ignition and Homogeneous Charge Compression Ignition

This paper presents an experimental and numerical evaluation of the pre-chamber induced HCCI combustion concept (PC-HCCI) in terms of engine performance, emissions, and controllability. In this concept, a spark-initiated combustion in the pre-chamber is utilized to trigger the kinetically controlled combustion of an ultra-lean mixture in the main combustion chamber. The experimental measurements were performed on a single-cylinder engine with a custom-made active pre-chamber. A high compression ratio of 17.5 was used, which limits the maximum achievable engine load due to high knocking tendency but enables both standard PCSI combustion (flame propagation) at very high dilution levels and HCCI combustion at reasonable intake temperatures. The analysis of combustion characteristics and the resulting performance is performed at indicated mean effective pressures (IMEPs) of 3.5 and 3.0 bars, and three different intake temperatures of 80 °C, 90 °C, and 100 °C. The variation in engine load was achieved by adjusting the excess air ratio in the main chamber. On each combination of intake temperature and engine load, a spark sweep and an injected PC fuel mass sweep were performed to obtain the highest indicated efficiency while satisfying the restrictions in terms of combustion stability and knock intensity. It was shown that, unlike in a conventional HCCI engine, the combustion phasing can be directly and reliably controlled by adjusting either spark timing or the reactivity of the pre-chamber mixture, ensuring adequate combustion stability and eliminating potential misfires. A similar indicated efficiency as with conventional HCCI combustion was obtained, while the NOx emissions, although slightly elevated, are still insignificant. Compared to PCSI combustion at the same engine load, a 4-percentage-point increase in indicated efficiency and two times lower NOx emissions were achieved. Compared to the most efficient PCSI operating point, it was 1 percentage point lower, indicating that efficiency was achieved, but the specific NOx emissions are reduced by approximately 70%. Most importantly, very similar performance was obtained with significant variations in intake temperature, proving the reliability and adaptability of this combustion concept.

Intertwined charge and spin density waves in a topological kagome material

Using neutrons and x rays we show the topological kagome antiferromagnet Mn3Sn for T<285K forms a homogeneous spin and charge ordered state comprising a longitudinally polarized spin density wave with wave vector kβ=kβĉ, a helical modulated version of the room temperature antichiral magnetic order with kχ=kχĉ, and charge density waves with wave vectors 2kβ,2kχ, and kβ+kχ. Though kχ and kβ coincide for 200K<T<230K, they exhibit distinct continuous Tdependencies before locking to commensurate values of kβ=112c* and kχ=548c* at lowT. Density functional theory indicates this complex modulated state may be associated with the nesting of Fermi surfaces from correlated flat kagome bands, which host Weyl nodes that are annihilated as it forms. Published by the American Physical Society 2024

Phased transition from methane to hydrogen in internal combustion engines: Utilizing hythane and direct injection jet ignition for enhanced efficiency and reduced emissions

A strategic pathway to decarbonizing internal combustion engines and advancing toward sustainable energy includes the transition from conventional fuels to methane combustion, followed by methane-hydrogen mixtures, and ultimately to hydrogen-only combustion. This progression leverages the miscibility of hydrogen and methane, enabling the use of Hythane, a fuel blend that combines the advantages of both gases. Methane's widespread availability and existing infrastructure facilitate a cost-effective transition, while its combustion produces lower emissions compared to gasoline and diesel. Hydrogen's high reactivity and clean combustion properties enhance engine efficiency and reduce emissions, making it a crucial component in this phased transition. Challenges in homogeneous charge compression ignition (HCCI) combustion of CH₄-H₂ mixtures, such as controlling ignition timing and managing stable combustion, are addressed by the direct injection jet ignition (DIJI) technique. DIJI creates stratified air-fuel mixtures that ensure rapid and complete combustion, minimizing quenching and reducing heat losses. This study presents a comprehensive analysis of the combustion properties of methane and hydrogen, the benefits of phasing the transition with the availability of green hydrogen, and the technical challenges and solutions in developing HCCI and DIJI combustion systems for Hythane. The research underscores the potential of DIJI to enhance engine performance, efficiency, and emissions control, paving the way for a sustainable energy future in transportation.

The Green Energy Effect on an HCCI Engine from Used Cooking Oil-based Biodiesel from Malaysia

Emissions from internal combustion engines (ICEs) significantly impact the environment, leading continents worldwide to work towards reducing them. The industry is increasingly leaning towards electric powertrains. However, power plants still utilize ICEs as generators, contributing to global pollution. Consequently, ICE emissions are garnering international attention. Alternatives like the Homogeneous Charge Compression Ignition (HCCI) engine and biodiesel fuels are being explored. HCCI engines have not been extensively tested with Used Cooking Oil (UCO) biodiesel. This study investigates the performance and emissions of HCCI engines using UCO-based biodiesel. This study tested an air-cooled, single-cylinder, 4-stroke diesel engine operating at 3600 rpm with a displacement of 0.219 liters. The HCCI mode was activated during preheating and run at 2700 rpm under varying biodiesel blend percentages and intake temperatures. In HCCI mode, brake-specific fuel consumption (BSFC) increased, peaking at a 90°C intake temperature. Diesel fuel in-cylinder pressure reached a maximum of 81 bars at 90°C, decreasing to 79 bars at 70°C. The HCCI mode resulted in lower NOx, CO, and UHC emissions. Higher biodiesel blend ratios further reduced CO emissions. Raising the intake air temperature to 90°C lowered NOx emissions by 96.66%, from 150 ppm to 5 ppm. Using green energy sources as fuel in HCCI engines significantly reduced emissions in this study, suggesting their potential as a future fuel for advanced engines.

Applying fischer tropsch and its pentanol blends into an aviation compression ignition engine for PM emissions control

The aviation industry is recovering from COVID-19 to regain rapid growth at an increasing rate of over 5 % annually. Aviation compression ignition (CI) engines attributed to their economic fuel consumption and adorable reliability, have been widely utilized in the general aviation (GA) industry. To fill in the knowledge gap of the compatibility of Fischer Tropsch (FT) blended with long-chain oxygenated fuel applied into the aviation engines, this research focuses on analyzing the combustion performance and particle matter (PM) emissions of an aviation CI engine by burning FT alternative fuel and its pentanol blends (FT80P20 - 80 % FT + 20 % pentanol), in comparison with baseline diesel/pentanol-diesel blends (D80P20 - 80 % diesel + 20 % pentanol). It was found that FT80P20 significantly increases the indicated thermal efficiency (ITE) by 6.5 %, and remarkably decreases the indicated specific fuel consumption (ISFC) by 12 % in contrast to neat diesel at high load (8.5 bar IMEP), which is due to better homogeneous charge that alternates heterogeneous combustion. Moreover, the PM size-resolved number distributions of emissions were characterized. It was observed that the integrated PM emissions from diesel were predominant (∼1.4 × 1014 #/kg∙fuel), while those from FT80P20 were significantly reduced by nearly 85 % (∼0.2 × 1014 #/kg∙fuel). Concurrently, the particulate geometric mean diameter (GMD) were decreased apparently from 80 nm to 35 nm correspondingly. The research findings reveal that “main diffusion combustion” was predominant as burning diesel, while “main premixed combustion” was prominent as using FT80P20, which has a promising impact on effective engine-work promotion with superior PM mitigation.

Evaluating the feasibility of machine learning algorithms for combustion regime classification in biodiesel-fueled homogeneous charge compression ignition engines

The present study explores the feasibility of machine-learning algorithms in classifying the combustion regimes in a homogenous charge compression ignition (HCCI) engine fueled with biodiesels from diverse sources. A distinctive feature of this research is the extensive database of HCCI combustion regimesgenerated for neat biodiesel fuels of different compositions. The engine experiments reveal significant variability in the load range of operation of HCCI engines across different biodiesel fuels. Strategies including compression ratio variation and charge dilution were employed to achieve higher engine loads, and the results confirm that the interplay of fuel reactivity and engine load, along with compression ratio and charge dilution, dictates the combustion stability. This complex phenomenon necessitates ascertaining the prevailing combustion type under a given engine load for biodiesel fuels derived from diverse sources. Thus, the present study aims to investigate the applicability of machine learning algorithms for developing models that classify combustion regimes in a neat biodiesel-fueled light-duty HCCI diesel engine. Models are developed to categorize biodiesel HCCI combustion into four groups: engine misfire, stable combustion without dilution, stable combustion with dilution, and knocking combustion. Biodiesel composition (13 different methyl esters), compression ratio and engine load are considered the input variables for the machine learning (ML) models. The results show that Naive Bayes and logistic regression models exhibit poor applicability among the investigated ML models due to a low F1 score (<0.8). The k-NN and SVM models demonstrate practical suitability with reasonably good F1 scores. However, the decision tree model outperforms all, precisely classifying 94 % of calibration and validation samples. It could precisely classify all the validation samples corresponding to misfire combustion, 21 of 22 samples to stable combustion, 4 of 6 samples to stable combustion with dilution, and 30 of 31 to knocking combustion. Thus, it emerges as the best approach to classify the combustion regimes of HCCI engines operated with neat biodiesel fuels.

Improving the combustion process of a homogeneous charge compression ignition engine running with triple fuel blend using response surface methodology

Improving the combustion process of a homogeneous charge compression ignition engine running with triple fuel blend using response surface methodology

Eco-FL: Enhancing Federated Learning sustainability in edge computing through energy-efficient client selection

In the realm of edge cloud computing (ECC), Federated Learning (FL) revolutionizes the decentralization of machine learning (ML) models by enabling their training across multiple devices. In this way, FL preserves privacy and minimizes the need for centralized data by processing data near the source. From a communication standpoint, only the model weights are exchanged between devices. By avoiding the need to send data to a centralized location for processing, FL reduces the energy required for data transfer and supports more efficient use of computing resources at the edge. FL is particularly advantageous for resource-constrained devices, such as smartphones and IoT devices. However, this limited computational power and battery capacity and the challenge of energy consumption are critical aspects of FL systems. This paper introduces Eco-FL, an innovative methodology designed to optimize energy consumption in FL systems, in the field of Green Edge Cloud Computing (GECC). Our approach employs a device selection process that considers the entropy of the data held by the devices and their available energy reserves. This ensures that devices with lower energy availability are less likely to participate in the training rounds, prioritizing those with higher energy capacities. To evaluate the efficacy of our methodology, we utilize FedEntropy, an entropy-based aggregation method, alongside established aggregation methods such as FedAvg and FedProx for performance comparison. The effectiveness of Eco-FL in reducing energy consumption without compromising the accuracy of the FL process is demonstrated through analyses conducted on three distinct datasets. These analyses vary the β parameter of the Dirichlet distribution and account for scenarios with both homogeneous and heterogeneous initial device charges. Our findings validate Eco-FL’s potential to enhance the sustainability of FL systems by judiciously managing client participation based on energy criteria, presenting a significant step forward in the development of energy-efficient FL.

Realisation of Low Temperature Combustion in an Unmodified Diesel Engine

Heavy-duty diesel engines are an essential part of road transportation. Since viable alternatives are not expected in the short and medium term, the problematic emission characteristics of compression ignition engines have to be addressed. Low temperature combustion (LTC) is an alternative combustion method for compression ignition engines that allows low particulate matter and nitrogen oxide emissions while improving efficiency. To overcome the difficulties of market introduction, the realization of such alternative combustion methods should come with marginal engine modifications. Thus, this work investigates the possible realization of LTC in an unmodified diesel engine. LTC methods with and without injection strategy modifications were also studied to provide sufficient recommendations for other researchers. It was concluded that techniques requiring early direct injection, such as homogeneous charge compression ignition (HCCI) require a narrow cone angle injector to reduce wall impingement. It was also concluded that modulated kinetics (MK) type LTC can be easily achieved by applying a conventional injection strategy and high amounts of cooled exhaust gas recirculation. The realized MK combustion resulted in an enhanced NOx-PM trade-off and a lower peak pressure rise rate compared to normal operation.