Conventional Combustion Research Articles

Parametric evaluation of ducted fuel injection in an optically accessible mixing-controlled compression-ignition engine with two- and four-duct assemblies

Ducted fuel injection (DFI) is a strategy to improve fuel/charge-gas mixing in direct-injection compression-ignition engines. DFI involves injecting fuel along the axis of a small tube in the combustion chamber, which promotes the formation of locally leaner mixtures in the autoignition zone relative to conventional diesel combustion. Previous work has demonstrated that DFI is effective at curtailing engine-out soot emissions across a wide range of operating conditions. This study extends previous investigations, presenting engine-out emissions and efficiency trends between ducted two-orifice and ducted four-orifice injector tip configurations. For each configuration, parameters investigated include injection pressure, injection duration, intake manifold pressure, intake manifold temperature, start of combustion timing, and intake-oxygen mole fraction. For both configurations and across all parameters, DFI reduced engine-out soot emissions compared to conventional diesel combustion, with little effect on other emissions and engine efficiency. Emissions trends for both configurations were qualitatively the same across the parameters investigated. The four-duct configuration had higher thermal efficiency and indicated-specific engine-out nitrogen oxide emissions but lower indicated-specific engine-out hydrocarbon and carbon monoxide emissions than the two-duct assembly. Both configurations achieved indicated-specific engine-out emissions for both soot and nitrogen oxides that comply with current on- and off-road heavy-duty regulations in the United States without exhaust-gas aftertreatment at an intake-oxygen mole fraction of 12%. High-speed in-cylinder imaging of natural soot luminosity shows that some conditions include a second soot-production phase late in the cycle. The probability of these late-cycle events is sensitive to both the number of ducted sprays and the operating conditions.

Centralized charging station planning for battery electric trucks considering the impacts on electricity distribution systems

To address environmental challenges resulting from transportation sector’s carbon emissions, replacing conventional internal combustion engine vehicles with electric vehicles is a key solution. Comprehensive electrification of heavy-duty trucks can promote the decarbonization of the freight transportation. The mismatch of supporting infrastructures is one of the major barriers to the deployment of battery-electric trucks (BET). BET charging behaviors and vehicle daily operations could influence the charging station planning and electricity distribution systems, which will cause the costs of upgrading distribution grid. This paper studies centralized BET charging station planning, considering the impacts of plug-in fast charging mode on the distribution systems. First, the BET model is proposed to capture BETs charging load profiles based on real-world operating data. Then, a mixed-integer programming model is formulated for charging station planning considering the upgrade requirements for distribution systems based on the BET model. After the co-optimization of centralized charging station planning and charging strategies of BET, the size of charging stations and charging schedules are determined. The results of numerical experiments indicate that charging demand from 50 BET can be met at current charging infrastructure technologies (>60 kW per charger) with a 37% reduction in the upgrade of distribution systems if incorporating managed charging strategy.

Thermal integration of styrene production process with chemical looping combustion to reduce the CO2 emission by omitting the conventional methane combustion furnaces

Upstream petrochemical units like olefins and aromatics are among the biggest emitters of greenhouse gasses Innovative technologies for carbon capture and storage have received increasing attention for adjusting the conventional methods of processes. The chemical-looping combustion (CLC) technology is an alternative method to supply the required heat for endothermic processes. In this work, we suggested the thermal coupling of the CLC process and the ethylbenzene dehydrogenation (EBDH) process, in a single-stage reactor. The two processes are integrated, and the porous medium of the fixed bed is used to simulate the reaction leading to styrene monomer. Then some critical parameters of the EBDH reactor and the CLC reactors are discussed and compared with valid results from previous simulations. Using a new structure and implementing several optimizations improved the yield of useful styrene monomer and key factors of the EBDH process.

Comprehensive Analysis of Power Systems for Hybrid Electric Vehicles

Now the pollution problem is becoming more and more serious, and the gas emitted by cars has seriously affected the environment. In order to reduce environmental pollution and Strength conservation and emission discount, sell the first-rate sustainable development of China's new electricity automobile industry, accelerate the development of vehicle strength, and the study of new energy vehicles is inevitable. New power vehicles are designed to use unconventional energy sources or indirectly use gasoline energy in a way that differs from conventional automotive internal combustion engines. The new power vehicle is the superior technology to complete the power control and driving of the vehicle which transcends the traditional technology and way. It is a vehicle with new technology as well as new structure. This paper mainly analyzes the energy conversion of hybrid electric vehicles, the advantages and disadvantages of the power system of hybrid electric vehicles, and also discusses the actual application of technology and the plate and management mode of power battery.

Investigation of Economical Design Strategies for the Solid Oxide Fuel Cell Afterburner Based on Computational Fluid Dynamics Simulation

This study simulates the computational fluid dynamics (CFD) to explore the design optimization strategies of the solid oxide fuel cell (SOFC) afterburner. The CFD modeling with combustion is carried out with the eddy dissipation concept (EDC), applying a three-step rate-dependent reaction mechanism to predict the determining step of the combustion reactions by changes of the control and design parameters. The implemented CFD model is validated by comparison of the precedent experimental data and CFD studies. The simulation results examine the temperature distribution and reactivity of the fuel inside the SOFC afterburner with design parameters at start-up operation, such as the equivalence ratio and swirl number. In particular, the results of the parametric study show the possibility of design optimization to minimize the wall temperature and constraints to reduce the emission of toxicants (i.e., CO and NOx). The alternative burner design derived from the parametric study, when starting the SOFC system, has been proven to keep on the stable thermal stress and fuel reactivity, despite lowering the maximum wall temperature to 80.9%, compared to the conventional burner design.

Optimal Planning of Electric Vehicle Charging Stations Considering Traffic Load for Smart Cities

The massive introduction of electric vehicles as a mobility alternative requires deploying an infrastructure of charging stations for electric cars (ICSEC). This new mobility concept will mitigate the environmental harm caused by the emission of CO2 generated by conventional internal combustion mobility methods. The sustainability of the ICSEC depends not only on the capacity to meet the demand for charging batteries for electric vehicles (EV) but also on an adequate number of public/private charging stations (CS) distributed in a geolocalized area. It is noted that the distribution of CS must respond to a set of real mobility constraints, such as vehicular flow capacity, road capacity, and trajectories. The planning, intelligent location of public charging stations (PCS), and contingency analysis will enable us to study the increase in demand for electrical distribution substations (EDS). Therefore, the present model explains the need to plan the massive introduction of EVs by observing the user’s conditions at the trajectory level through finite resource allocation processes, segmentation, and minimum spanning trees, by observing heterogeneous vehicular flow criteria through microscopic analysis, to understand the space–time relationship of vehicular flow in georeferenced scenarios. Consequently, the computational complexity of the model is of the combinatorial type, and it is defined as NP-Hard given the multiple variables and constraints within the transportation problem.

Charge Equalization System for an Electric Vehicle with a Solar Panel

Electric vehicles are environmentally friendly and more efficient than conventional combustion vehicles. However, from the point of view of energy vectors, they may use energy produced by less efficient and more polluting means. In this paper, an applicative methodology is used to develop a charging equalizer for an electric vehicle that makes it possible to efficiently use the energy produced by a 350 W photovoltaic panel to intelligently charge the five batteries of the vehicle. In addition, using a quantitative methodology, an analysis of the different physical and electrical parameters obtained by a series of sensors installed in the vehicle is presented, and the efficiency of the system is determined. Different routes were travelled within the city of Cuenca with and without the load equalization system, which made it possible to determine an increase in vehicle efficiency of up to 27.9%, equivalent to an additional travel distance of approximately 14.35 km. This is a promising result, since with small investments in solar panels and electronic materials, the performance of low-cost electric vehicles can be significantly improved.

Comparative evaluation of combustion, performance, exergy and emission characteristics in hydrogen-biodiesel dual fuel engine under RCCI mode

The present work focuses on the impact of combustion phase shifting from CDC (conventional diesel combustion) to RCCI (reactivity controlled compression ignition) mode of operation under various premixed ratios of hydrogen on the combustion, performance and exhaust emissions of a partially modified CI (compression ignition) engine. The hydrogen premix ratios are varied from 10% to 60% with 10% increment and the engine is tested at 0.9 kW, 1.8 kW, and 2.7 kW. The experimental results have shown that the hydrogen participation up to 40% premixed ratio improves the homogeneousness and stability of the combustion, resulting in 8.19% increase in cylinder pressure and 27.81% increase in heat release rate (HRR) at 2.7 kW brake power. It is also observed that the premix phase of combustion is faster with up to 40% hydrogen participation as the 50% mass burn is found to shift towards TDC. At the same operating point, the combustion is also found to be more stable with 72% reduction in COVIMEP. The brake thermal efficiency (BTE) increases by 10.07% when operating at 2.7 kW brake power with a 40% premix ratio, compared to diesel CDC operation. The unburned hydrocarbon (UHC), carbon monoxide (CO), and PM emissions are reduced by 9.17%, 21.68%, and 9.51%, respectively, for the hydrogen premixed ratio of 40%, with a marginal increase in the oxide of nitrogen (NOX) emissions.

A study on the combustion performance and NOx emissions characteristics of a novel U-type radiant tube based on MILD combustion theory

Based on the theory of moderate or intense low-oxygen dilution (MILD) combustion, a 3D steady-state CFD model coupling dual flue gas recirculation and dispersion combustion was developed to describe the flow field, combustion temperature field, wall temperature distribution, and NOx concentration field during the operation of a novel U-type radiant tube (N-URT). A user-defined function (UDF) method was implemented to simulate the dilution of O2 concentration in the combustion air due to external flue gas recirculation (E-FGR). The effects of the E-FGR ratio on combustion characteristics and NOx emission were evaluated. The simulated results were consistent with experimental results. The simulated NOx concentration at the outlet was reduced to 105.5 mg/m3 at 8% O2, which was about 35.2% lower than the conventional combustion method. The study found that when the E-FGR ratio was increased from 0 to 25%, the standard deviation of wall temperature decreased from 30.3 °C to 23.3 °C, and the non-uniformity coefficient decreased from 0.2598 to 0.2183, indicating an improvement in temperature uniformity. However, the thermal efficiency decreased from 82.1% to 76.2%. Moreover, at higher E-FGR ratios, the volume of the high-temperature region (above 1500 ℃) gradually decreased, and both the maximum flame temperature and the outlet NOx concentration decreased sharply. Regression equations for the E-FGR ratio (β) on the maximum combustion temperature (Tmax) and the outlet NOx concentration (CNOx) were obtained, and an E-FGR ratio greater than 13.4% was recommended to meet the emission requirements.

Additive manufacturing new piston design and injection strategies for highly efficient and ultra-low emissions combustion in view of 2030 targets

Internal combustion engines have been the most effective solution as the main mover for mobility. Despite the recent European regulations targeting zero tailpipe CO2 emissions for new passenger cars and light vans from 2035 onwards, the upcoming emission regulations still require further technology and fuel developments in the transport sectors. In recent years, studies on internal combustion engines have been increasingly shifting from performance and refinement through advanced fuel injection and air charging technologies to ultra-low emissions and efficiency. Particular attention has also been paid to carbon–neutral fuels. The problem merits further investigation since all are key factors for the powertrain competitiveness in the electrified automotive future, as the pollutants and the CO2 emissions will soon approach the Euro 7 regulation and the Fit to 55 standards, respectively. To this aim, the combustion system design is a crucial part of the internal combustion engine development in the view of exploiting renewable fuel characteristics. This study seeks to assess the effectiveness of a steel piston, realized through a specific design for additive manufacturing technologies, enabling an innovative bowl geometry. It features a highly re-entrant sharp-step and radial lips bowl profile enabling spray separation and radial mixing zone concept. A single-cylinder compression ignition engine has been employed to demonstrate the effectiveness of the innovative bowl shape to meet the challenging future ultra-low emission targets. The results confirm the additive manufacturing technology as a possible solution for innovative highly-stressed steel piston designs. The new bowl shape design, combined with optimised spray targeting and injection strategies, allows outstanding soot reductions, up to 80%, and ultra-low NOx emission levels compared to the conventional combustion system. Gains in fuel economy are also observed. Further emissions advantages are expected with renewable fuel applications.

Partially premixed combustion of diesel-di-ethyl ether blends in light-duty commercial engine

Diethyl ether (DEE) has evolved as a potential alternative for partial diesel replacement in compression ignition (CI) engines. In this study, a light-duty commercial diesel engine was operated in partially premixed combustion (PPC) mode. This work investigated the engine characteristics with lower and higher DEE-diesel blends in PPC mode. The split ratio and the start of the main injection (SoMI) timings were maintained at 70:30 (Main: Pilot) and 9° bTDC, respectively, while the start of the pilot injection (SoPI) timing was varied from 25 to 40° bTDC. The performance, combustion, and regulated emission characteristics of the PPC engine were compared with the conventional diesel combustion (CDC) mode as a baseline. The PPC mode exhibited higher/ comparable brake thermal efficiency (BTE) than the baseline CDC mode. The DEE-diesel blends exhibited higher BTE than the diesel in PPC mode generally. The DEE40 showed greater improvement in BTE than DEE20 at lower brake mean effective pressure (BMEP). PPC mode fuelled with diesel and diesel-DEE blends showed lower brake specific fuel consumption (BSFC) than baseline CDC mode at lower BMEP, but it was comparable at higher BMEP. PPC mode showed higher carbon monoxide (CO) emissions than baseline CDC mode. CO emissions increased with advancing SoPI timing for all BMEPs, except 5.6 bar. Although, the PPC mode exhibited higher hydrocarbon (HC) emissions than the CDC mode. Diesel-DEE blends showed slightly higher HC emissions than diesel in PPC mode at lower engine BMEPs. NOx emissions in the PPC mode were 1.5 to 2 times the baseline CDC mode. This indicated that the PPC mode engine performance requires further optimization similar to CDC mode, which had optimized exhaust gas recirculation (EGR), and significantly reduced the nitrogen oxide (NOx) emissions.

Experimental investigation on flame stability and emissions of lean premixed methane–air combustion in a developed divergent porous burner

Flame stability and pollutant emissions are issues of the greatest concern for low-calorific-value gas combustion. Although the conventional straight porous burner is conducive to improving the flame stability, it still cannot meet the industrial demand. To improve the flame stability and reduce the pollutant emissions during fuel-lean combustion, a divergent double-layer porous burner was creatively proposed in this study. The influences of the inlet velocity and equivalence ratio on the flame stability, temperature distributions, the emissions were experimentally investigated in detail. The results showed that the flame front gradually moved downstream, the preheating zone length increased as the inlet velocity increased. Compared with the traditional straight porous burner, the divergent porous burner extended the blowout limit by 300%. Since the burner was operated under fuel-lean conditions (the equivalence ratio range was 0.45–0.6), the CO emissions were relatively high when the inlet velocity was less than 0.4 m/s. When the inlet speed was equal to or greater than 0.4 m/s, the maximum CO emissions concentration was 132 ppm. The burner showed superior performances in terms of NO emissions, with emissions concentrations of less than 20 ppm under all test conditions. In summary, the great advantage of the divergent porous burner lies in extending the flame stability limit. For clean combustion it is recommended that the burner be operated at a higher velocity (greater than or equal to 0.4 m/s) to obtain lower CO and NO emission levels.

Molecularly-controlled high swirl combustion system for ethanol/1-octanol dual fuel combustion

To achieve future targets for reducing greenhouse-gas and pollutant emissions from internal combustion engines, alternative fuels as well as alternative combustion modes offer great potential. The simultaneous use of two different fuels offers additional degrees of freedom to realize highly efficient and low-emission combustion, but also poses further challenges. To this end, this paper presents the Molecularly-Controlled high swirl Combustion system, MCC, which involves dual direct injection of a low- and a high-reactivity fuel in combination with lean relative air-fuel-ratios, high compression ratio, and compression ignition. The principle centers on the generation of a strong “molecular spark” – a spacially confined area in the combustion chamber where the reactivity of the fuel mixture is sufficient to form a robust, controllable ignition source. Subsequently, combustion spreads to the rest of the combustion chamber. Ethanol was used as the low-reactivity fuel and 1-octanol or conventional diesel fuel as the high-reactivity fuel to investigate the combustion characteristics, efficiency, and raw emission potential under various operating conditions with a light-duty single-cylinder research engine. The results are compared with compression ignition operation of conventional diesel fuel and neat 1-octanol. The MCC system achieves a large reduction in soot-emissions, even at very low NOx-levels below 0.1 g/kWh and a considerable increase in indicated efficiency over conventional compression ignition combustion.

Strength, weakness, opportunities, and threats (SWOT) analysis of fuel cells in electric vehicles

Fuel cell electric vehicles have the advantages of simple assembly, higher efficiency, and quiet operation compared to any other propulsion method. While there is a clear road map on the future of fuel cell electric vehicles, there is still a need for a paradigm shift to relent on using fossil fuels as soon as possible. The majority of the reviewed literature focuses on enhancing the current performance of the fuel cell electric vehicle technology for the transportation sector. However, detailed information for policy makers and the research communities on the current state of the technology is evidently missing. This study presents a detailed and holistic examination of fuel cell electric vehicle technology's current state and prospects. A systematic SWOT analysis on the technology is presented to highlight major factors impeding the proliferation of the technology up to widespread commercialization. Despite the progress made, the uncertainty of market trends requires further studies to allow fuel cells to compete fairly with existing infrastructure like the one available for conventional internal combustion engines.

Reinforcement Learning-Enabled Electric Vehicle Load Forecasting for Grid Energy Management

Electric vehicles are anticipated to be essential components of future energy systems, as they possess the capability to assimilate surplus energy generated by renewable sources. With the increasing popularity of plug-in hybrid electric vehicles (PHEVs), conventional internal combustion engine (ICE)-based vehicles are expected to be gradually phased out, thereby decreasing greenhouse gases and reliance on foreign oil. Intensive research and development efforts across the globe are currently concentrated on developing effective PHEV charging solutions that can efficiently cater to the charging needs of PHEVs, while simultaneously minimizing their detrimental effects on the power infrastructure. Efficient PHEV charging strategies and technologies are necessary to overcome the obstacles presented. Forecasting PHEV charging loads provides a solution by enabling energy delivery to power systems based on anticipated future loads. We have developed a novel approach, utilizing machine learning methods, for accurately forecasting PHEV charging loads at charging stations across three phases of powering (smart, non-cooperative, and cooperative). The proposed Q-learning method outperforms conventional AI techniques, such as recurrent neural and artificial neural networks, in accurately forecasting PHEV loads for various charging scenarios. The findings indicate that the Q-learning method effectively predicts PHEV loads in three scenarios: smart, non-cooperative, and cooperative. Compared to the ANN and RNN models, the forecast precision of the QL model is higher by 31.2% and 40.7%, respectively. The Keras open-source set was utilized to simulate three different approaches and evaluate the efficacy and worth of the suggested Q-learning technique.

Combustion behavior study and flame zone analysis of biogas-fueled gas turbine combustor under O2/CO2 and O2/H2O oxidizing modes

Environmental problems resulting from the increment of greenhouse gases have raised the tendency toward using renewable energy sources alongside carbon-capturing technology via oxyfuel combustion. In this regard, numerical simulation on the feasibility of using renewable biogas in the gas turbine combustor under two combustion modes, namely, O2/CO2 and O2/H2O, at high operating pressure is investigated in the current research. Considering that conventional air-based combustion systems are not suitable for oxyfuel combustion regimes, the modification of the gas turbine combustor will be addressed to provide the necessary conditions for proper operation at higher power densities on an industrial scale. In this study, the focus is on investigating the influences of the primary diluent mass flow rate ratio (PDR) and the O2 content in the oxidizer composition on combustion and thermal behaviors of biogas flame such as distribution of reaction zone and temperature, combustion species, pattern factor, combustion efficiency, CO pollutant emission, and as well as flame stability in different combustion modes. The results indicated that the PDR parameter plays an essential role in the combustion stability within the gas turbine combustor due to its direct exposure to the vortices created in the recirculation zone. Moreover, combustion instabilities were observed for biogas flame at PDR = 15% in both combustion modes and in O2/H2O case at PDR < 25%. It was also found that CO emissions decrease significantly with increasing PDR, so in higher PDR values, CO pollutant levels were observed at 39 ppm and 21 ppm in O2/CO2 and O2/H2O cases, respectively.

A Novel Levy-Enhanced Opposition-Based Gradient-Based Optimizer (LE-OB-GBO) for Charging Station Placement

Transportation modes are shifting toward electric vehicles from conventional internal combustion engines to reduce pollution and dependency on conventional fuels. This reduces the fuel cost, while charging stations must be distributed across the locations to minimize range anxiety. Installing charging stations randomly across the distribution system can lead to violation of active power loss, voltage deviation, and reliability parameters of the power system. The problem of the optimal location of charging stations is a nonlinear optimization problem that includes the parameters of the distribution system and road network with their respective constraints. This work proposes a new metaheuristic optimization algorithm, a levy-enhanced opposition-based gradient-based optimizer (LE-OB-GBO), to solve the charging station placement problem. It has a balance between exploration and exploitation and fast convergence rate. The performance of the proposed algorithm was evaluated by solving CEC 2017 benchmark functions and charging station problem. The performance of the proposed algorithm was also compared with that of other state-of-the-art optimization algorithms and was found to outperform 17 out of 29 CEC 2017 functions. Statistical analysis of the charging station placement problem indicates the lowest mean values of 1.4912, 1.4783, and 1.5217 for LE-OB-GBO for considered cases 1 to 3, respectively, thus proving the efficacy of the proposed algorithm.

A CFD Study on the Effects of Injection Timing and Spray Inclusion Angle on Performance and Emission Characteristics of a DI Diesel Engine Operating in Diffusion-Controlled and PCCI Modes of Combustion

In three-dimensional (3D) computational fluid dynamics (CFD) simulations, the effects of injection timing and spray inclusion angle (SIA) on performance and emissions of diffusion-controlled and Premixed Charge Compression Ignition (PCCI) combustion in part load for a heavy-duty direct injection (HDDI) diesel engine are studied. The start of injection (SOI) of a 146° SIA injector is varied between −70 and −10 °crank angle (°CA) after top dead center (ATDC). For −50 °CA ATDC SOI with various SIAs between 80° and 146°, PCCI combustion reduces mono-nitrogen oxide (NOx) emissions significantly compared to conventional diesel combustion (CDC). Due to incomplete combustion in rich zones formed by droplet–cylinder wall interaction, early wide SIA injection deteriorates combustion efficiency (CE) and Indicated Mean Effective Pressure (IMEP) and increases soot and carbon monoxide (CO) emissions. Narrow-angle sprays interacting with the piston bowl elevate CE and IMEP and decrease soot and CO emissions but increases NOx emissions. Optimal combustion is achieved by avoiding fuel droplet–cylinder wall interaction. By spray-targeting at the stepped lip of the piston bowl, 100° SIA and −50 °CA ATDC SOI yield, respectively, the highest CE and IMEP: 97.8% and 3.37 bar and the lowest soot and CO emissions: 33.5 and 2.2 ppm, with acceptable NOx emissions.

Parametric optimization with Biodiesel-water emulsion under premixed lean combustion to achieve high efficiency and clean combustion

Advanced low temperature combustion (LTC) aids in simultaneously controlling exhaust emissions of oxides of nitrogen (NOx) and particulate matter (PM). However, LTC strategies are constrained by achievable load range restriction and higher levels of unburned hydrocarbon (HC) and carbon monoxide (CO). The present investigation envisages combining renewable biodiesel-water emulsions and an advanced premixed lean combustion strategy to curtail the higher HC and CO emissions without sacrificing engine performance. Non-edible Karanja oil was the source of biodiesel and the emulsion stabilizer. A production light-duty diesel engine is modified to run under premixed lean combustion conditions based on late injection using a fully-flexible electronic fuel injection system. The engine operating parameters were optimized, including fuel injection timing, EGR flow rate, and emulsion water concentration. Emulsions of neat biodiesel were prepared to contain 6, 12, and 18% water on a mass basis using 1 and 2% surfactant by mass. The fuel injection timing was varied from 2 to 4 degrees after the top dead centre, and up to 15% EGR flow rate was utilized. Design of experiments aided in minimizing the number of engine tests. The performance and emission parameters were the output responses. Taguchi Grey Relational Analysis established the optimal combination of input factors to improve engine performance and reduce exhaust emissions. Engine experiments at optimized operating conditions revealed that compared to conventional diesel combustion, the brake thermal efficiency and brake specific fuel consumption improved by 33 and 16%, respectively, at 5.08 bar BMEP. The NOx, smoke and HC emissions were reduced by 68, 73 and 46%, while CO emissions increased nearly two-fold.

Experimental Evaluation of Pilot and Main Injection Strategies on Gasoline Compression Ignition Engine—Part 1: Combustion Characteristics

&lt;div&gt;Climate change and stringent emission regulations have become major challenges for the automotive sector, prompting researchers to investigate advanced combustion technologies. Gasoline compression ignition (GCI) technology has emerged as a potential solution, delivering higher brake thermal efficiency with ultra-low nitrogen oxides (NOx) and particulate emissions. Combustion stability and controls are some of the significant challenges associated with GCI. This study investigates the combustion characteristics of a two-cylinder diesel engine in GCI mode. GCI experiments were performed using a low-octane fuel prepared by blending 80% (v/v) gasoline and 20% (v/v) diesel (G80). Baseline experiments were conducted in conventional diesel combustion (CDC) mode. These experiments investigated the effects of double pilot injection, first pilot fuel ratio, and the start of main fuel injection timing (10–8°CA before top dead center, bTDC). The results indicated that the GCI mode produced significantly lower (~10%) in-cylinder pressure than the CDC mode. Higher pilot fuel proportions exhibited a lower heat release rate (HRR) at low loads. Retarded main injection showed a lower heat release in the premixed combustion phase than the advanced main injection case at all loads. In addition, retarded main injection timing showed retarded start of combustion (SoC) and end of combustion (EoC). GCI mode exhibited higher cyclic variations than baseline CDC mode, which need to be addressed.&lt;/div&gt;