Fuel-air Equivalence Ratio Research Articles

Thick reaction zones in non-flamelet turbulent premixed combustion

Internal structure of extremely turbulent flames is investigated experimentally using simultaneous planar laser-induced fluorescence of formaldehyde molecule and hydroxyl radical as well as stereoscopic particle image velocimetry. The mean bulk flow velocity is changed from 5 to 35 m/s. The fuel-air equivalence ratio is 0.7 for all tested conditions. Three different turbulence generating mechanisms leading to a wide range of turbulence intensity with the corresponding Reynolds and Karlovitz numbers ranging from 19 to 2729 and 0.3 to 76.0, respectively, are examined. Preheat and reaction zone thicknesses for the tested flames are calculated and compared with those of the laminar flame to quantify deviation from flamelet behavior. It is shown that the preheat and reaction zone thicknesses increase to values that are about 6.2 and 3.9 times the laminar flame counterparts, respectively. While broadening of the preheat zone is reported in the literature, broadening of the reaction zone for a relatively large diameter Bunsen burner is reported for the first time in this study. The broadening of the reaction zones is related to non-flamelet behavior of the tested flames, and a parameter proposed earlier by the authors is used to quantify this non-flamelet behavior. Swirling strength contours are overlaid on the cold reactants and preheat zones to study the reason for the reported broadening. The results show that positive correlations exist between the preheat/reaction zone thicknesses and the mean value of eddy swirling strength inside the reactants and preheat zone. These correlations as well as the estimated turbulent kinetic energy of these eddies suggest that energetic eddies may potentially penetrate into the preheat and reaction zones causing broadening of these zones.

Importance of flue gas cooling conditions in particulate matter formation during biomass combustion under conditions pertinent to pulverized fuel applications

Laboratory-scale experiments pertinent to pulverised fuel (PF) combustion are often carried out in drop-tube furnaces (DTFs) at air-fuel equivalence ratios and cooling rate for quenching flue gas that are much higher than those in PF boilers. This paper reports the effect of flue gas cooling conditions on the properties of PM with aerodynamic diameter of <10 µm (PM10) from biomass combustion. This study considers four cooling rates (1000, 2000, 6000 and 20,000 °C/s) and two biomass feeding rates (0.05 and 0.25 g/min) that represents flue gases with significantly-different concentrations of inorganic vapours. The PSDs of PM10 have a bimodal distribution with a fine mode within PM with aerodynamic diameter of <1 µm (PM1) and a coarse mode within PM with aerodynamic diameter of 1–10 µm (PM1–10). All experimental conditions produce PM10 with similar PM1 and PM1–10 yields (∼0.8 and ∼1.6 mg/g_biomass, respectively) and similar coarse mode diameters (i.e. 6.863 µm). However, at a biomass feeding rate of 0.05 g/min, the fine mode diameter shifts from 0.022 to 0.077 µm when the cooling rate decreases from 20,000 to 1000 °C/s, indicating more profound heterogeneous condensation at a lower cooling rate. As the biomass feeding rate increases to 0.25 g/min, the fine mode diameter further shifts to 0.043 µm and at 20,000 °C/s but remained at 0.077 µm at 1000 °C/s though a clear shift of PSD to larger diameters is evident. These are attributed to enhanced heterogeneous condensation and coagulation of small particulates resulting from increased particle population density in hot flue gas. Chemical analyses show PM1 contains dominantly volatile elements (i.e. Na, K and Cl) while PM1–10 consists of mainly Ca. Similar trends are also observed for elemental PSDs and yields. It is also observed that slow cooling of hot flue gas leads to an increased yield of Cl in PM1–10 due to enhanced chlorination of Ca species.

Experimental investigation of wastewater microalgae in a pilot-scale downdraft gasifier

Microalgae are potential feedstock for biofuels due to higher heating value and rapid growth rate. It can be cultivated in sewage, avoiding costs associated with clean water and nutrients, making the possibility of energy generation from wastewater treatment plants appealing. Compact microgeneration systems involving biomass gasifiers are already commercialized for small-scale projects and could be adapted for use with microalgae in wastewater. In this study, an experimental investigation of a commercial downdraft gasifier was conducted using microalgae produced in a wastewater treatment plants. The effects of the air-fuel equivalence ratio on syngas composition, higher heating value, and production rates were evaluated. An increasing and then decreasing trend in equivalence ratio with a peak was observed, indicating that the optimum equivalence ratio for the best performance is 0.23. The cold gas efficiency was 87%, higher heating value was 6.2 MJ/Nm3, and the production rate was 2.8 Nm3/kg dry biomass. The syngas composition was 11.9% H2, 19.5% CO, 8.5% CxHy, and 9.8% CO2. The H2/CO ratio observed in the syngas was 0.61, which is very close to the 0.60 recommended for synthetic fuel production (Fischer-Tropsch gasoline and diesel).

An experimental investigation on combustion and performance characteristics of supercharged HCCI operation in low compression ratio engine setting

This study investigates the effects of boost pressure on combustion and performance of an early direct injection homogenous charge compression ignition (HCCI) engine at a low compression ratio (CR). A 2.0 L, four-cylinder, four-stroke, gasoline direct injection engine was converted to operate in early direct injection HCCI mode. In addition, a supercharger unit was developed for engine boosting. The experiments were performed at different intake manifold absolute pressures (MAP) from 1.0 to 1.6 bar at different engine loads using n-heptane fuel. The effects of boost pressure were investigated on HCCI combustion and engine performance characteristics using volumetric efficiency, in-cylinder pressure, heat release rate (HRR), maximum in-cylinder pressure and gas temperature, CA50 (crank angle by which 50% of the fuel is burnt), combustion duration, apparent combustion efficiency, indicated mean effective pressure (IMEP), brake mean effective pressure (BMEP), friction mean effective pressure (FMEP), indicated thermal efficiency (ITE), brake thermal efficiency (BTE), heat loss, exergy of heat loss, coefficient of variation of IMEP (COVIMEP), maximum pressure rise rate (MPRR) and ringing intensity (RI). The experimental results showed that high-efficiency HCCI operation is feasible at an engine compression ratio as low as 9.2 once the engine variables are properly optimized and an appropriate level of supercharging is utilized. An increase in indicated thermal efficiency was seen as boost pressure increased. In addition, combustion phasing advanced by increasing boost pressure or increasing air–fuel equivalence ratio values. Combustion events with CA50 2–3 °CA aTDC show the highest thermal efficiency especially at low boost pressure conditions. In addition, the pressure rise rate and ringing intensity increased by increasing air–fuel equivalence ratio and MAP. The test results also showed that HCCI operating range can be extended with the increase of intake manifold pressure especially at high load limits.

Efficiency and raw emission benefits from hydrogen addition to methane in a Prechamber–Equipped engine

Providing high ignition energies to low reactivity (hard-to-ignite) fuels in premixed combustion modes is a challenging task. This is especially true if diluted combustion and high compression ratios are applied which are desirable for achieving high efficiency levels. One promising technology is to decouple the ignition process from the conditions in the main chamber using a prechamber, which is able to ignite the charge in the engine's main combustion chamber using turbulent jets. In this study, experimental results of a prechamber-equipped four-cylinder engine with 2 L displacement are discussed. The engine is designed to provide high efficiency using natural gas as a fuel. The prechamber is able to be fueled externally (called active prechamber mode), e.g. the air–fuel equivalence ratio λ can be decoupled from the λ in the main combustion chamber. Besides of pure methane operation, the engine is operated with the addition of 22.5 mol% (3.5 mass%, 8.0 energy%) hydrogen to methane. The results show that it is beneficial to use auxiliary fueling of the prechamber in pure methane operation mode in order to achieve highest possible efficiency at low NOx levels at λ of around 1.7. When adding hydrogen, λ of around 1.7 still provides highest efficiency but auxiliary fueling of the prechamber is not necessary any more to enable fast and robust combustion. Compared to the active prechamber operation with methane, the 3.5 mass% (8.0 energy%) addition of hydrogen is able to reduce the engine's fuel energy demand by 1.3–3.3% in relevant engine operating points, which leads to tailpipe CO2 reductions of 9.2–11%. Additionally, hydrogen addition is able to disproportionately lower the engine's unburned hydrocarbon (HC) emissions: The addition of 3.5 mass% hydrogen lowers HC mass emissions by impressive 30–40%. Simultaneously, at the lean conditions considered, CO and NOx emissions are lowered by around 20%.

Large eddy simulations of turbulent combustion of kerosene-air in a dual swirl gas turbine model combustor at high pressures

In advanced gas turbine engines, high-pressure combustion generally occurs with combustion chamber pressure exceeding the critical pressure of the engine fuel. In this paper, large eddy simulations are conducted in a dual swirl gas turbine model combustor to analyze the effects of different fuel-air equivalence ratios and chamber pressures on swirling injection and turbulent combustion. Numerical results reveal that intricate interactions exist between swirling flows and high-pressure turbulent flame. Strong swirling injection of air could cause reverse flows in the inner injector, which lead to a V shaped partially premixed turbulent flame at a chamber pressure of 3 MPa. As the operating pressure increases to 5 MPa, decreased injection velocity would prevent reverse flows in the inner injector, leading to the turbulent diffusive flame. On the other hand, combustion causes flow acceleration, gaseous expansion, and strong thermophysical property variations, which would influence the reverse flows, increase the expansion angle in swirling injection, and dictate the size of central recirculation zone and the oscillation frequency of precessing vortex core. Results obtained herein would help gain fundamental understanding on high-pressure swirling flows and flame dynamics in advanced gas turbine engines.

Parametric Knocking Performance Investigation of Spark Ignition Natural Gas Engines and Dual Fuel Engines

Both spark ignition (SI) natural gas engines and compression ignition (CI) dual fuel (DF) engines suffer from knocking when the unburnt mixture ignites spontaneously prior to the flame front arrival. In this study, a parametric investigation is performed on the knocking performance of these two engine types by using the GT-Power software. An SI natural gas engine and a DF engine are modelled by employing a two-zone zero-dimensional combustion model, which uses Wiebe function to determine the combustion rate and provides adequate prediction of the unburnt zone temperature, which is crucial for the knocking prediction. The developed models are validated against experimentally measured parameters and are subsequently used for performing parametric investigations. The derived results are analysed to quantify the effect of the compression ratio, air-fuel equivalence ratio and ignition timing on both engines as well as the effect of pilot fuel energy proportion on the DF engine. The results demonstrate that the compression ratio of the investigated SI and DF engines must be limited to 11 and 16.5, respectively, for avoiding knocking occurrence. The ignition timing for the SI and the DF engines must be controlled after −38°CA and 3°CA, respectively. A higher pilot fuel energy proportion between 5% and 15% results in increasing the knocking tendency and intensity for the DF Engine at high loads. This study results in better insights on the impacts of the investigated engine design and operating settings for natural gas (NG)-fuelled engines, thus it can provide useful support for obtaining the optimal settings targeting a desired combustion behaviour and engine performance while attenuating the knocking tendency.

Experimental investigation of burning of pulverized peat in a bidirectional vortex combustor

The paper reports on the results of experimental research of bidirectional vortex combustor operation at different modes. This combustor implements a new idea of burning solid pulverized fuel in a bidirectional swirling flow. The experimental results confirmed the thesis about a wide range of stable operation of the combustor, as well as its environmental friendliness: the values of exhaust emission of CO and NOx are significantly lower than those for the direct-flow combustor. Besides, such combustor can operate in two modes: as an igniter or stabilizer of boiler furnace, where it generates a stable high-enthalpy flame as well as an independent device with low emission values. A summary of research results defines that the most environmentally friendly operating mode is achieved at the net air-fuel equivalence ratio λΣ = 1.3 and the ratio of primary and secondary air mass flow rates n = 2.7.

Experimental investigation of the ignition characteristics of vaporized RP-3 kerosene in supersonic flow

The ignition characteristics of vaporized RP-3 kerosene were experimentally investigated in a cavity-based Mach 2.52 scramjet combustor. The simulated flight condition was Ma 5.5 at 25 km, while the entrance had a stagnation temperature of 1486 K and a total pressure of 1.6 MPa. With high-speed photography and chamber pressure measurement, the effects of fuel temperature on ignition performance were studied under a lean fuel condition, and the mechanism of ignition failure during the fuel temperature increasing was investigated. The results showed that increasing the injection temperature could accelerate the atomization and evaporation processes of the fuel droplets, reduce the ignition delay time, and enhance combustion in the cavity. However, a critical point (about 567 K) was found in vaporized kerosene ignition. When the injection temperature approached this point, the phase of the kerosene jet transited sharply, and the penetration depth increased. It decreased the fuel-air equivalence ratio in the cavity, deteriorating the reaction environment and causing ignition failure. The blow-out process had a similar evolution at different injection temperatures. Flame in-cavity was repeatedly stretched and merged with dissipating heat, and eventually blown off near the bottom. The flame residence time was closely related to the discharge time of the spark plug.

A numerical simulation of burning of pulverized peat fuel in a bidirectional vortex combustor

Bidirectional (or countercurrent) vortex combustors are some of the most promising vortex-flow devices in terms of the fuel and oxidizer mixing efficiency, the combustion efficiency, the emission characteristics, and the combustion stability. This paper suggests a new arrangement principle for combustion of solid pulverized peat in conditions of vortex countercurrent flow which has never been studied earlier; we developed a combustion unit implementing this principle and carried out a numerical analysis of the combustion process with various operating parameters. The calculation results confirmed the possibility of combustion within a wide range of parameters and showed that varying the air-fuel equivalence ratio from λ = 0.5 to λ = 5.05 results in significant change in both the structure of the limited vortex flow and the distribution of total pressure and temperature, as well as the averaged volume concentration of fuel particles. We calculated the boundaries of lean and rich flame blowouts where the gas-dynamic flow loses its stability and the toroidal vortex is disrupted. At the same time, secondary vortex structures are formed throughout the combustor volume.

Optimization of operation strategies of a syngas-fueled engine in a distributed gasifier-generator system driven by horticulture waste

This work optimized the operation of a syngas-fueled spark ignition (SI) engine in the gasifier-generator (GG) system to achieve improved combustion performance and reduced emission adapting to the electrical power output. The combustion performance and emissions of the SI engine were modeled by an experimentally validated 3D KIVA4-CHEMKIN model with a detailed GRI 3.0 mechanism. Effects of the ignition timing (IT), fuel–air equivalence ratio (FAER), inlet temperature, and power load on the energetic, knock and environmental performance of the SI engine were investigated by analyzing the in-cylinder pressure, heat release, indicated thermal efficiency (ITE), NOx emission, peak temperature and maximum pressure derivative (MPD). When IT increases from 14 to 50 crank angle degrees (CAD) before top dead center (BTDC), the ITE first increases and then decreases, while the NOX emission, peak temperature, and MPD keep increasing. In the range of IT from 14 to 50 CAD, FAER from 0.5 to 0.9, inlet temperature from 300 to 407 K, potential space of optimization variables was figured out in the phase diagram of NOx emission vs. ITE at each power load of 4–10 kW. The optimal IT, FAER, and intake air temperature parameters were selected from the Pareto front of the potential optimization space using the ideal point method. The results show that the load-related control strategy can achieve high ITE values of 39.01–39.69% and satisfactory nitrogen oxide emissions of 0.6–1.55 g/kWh. The optimization method and optimal operation parameters provide references for improving engine performance in the GG system.

Experimental study on combustion of CH4/NH3 fuel blends in an industrial furnace operated in flameless conditions

This paper presents the results of an experimental study on the combustion process of methane mixed with NH3 in flameless mode. At a time of striving for CO2-free power, NH3 became a potential energy storage carrier fuel from renewable sources. Flameless combustion features low emissions and is a very efficient technology used in the power sector, as well as steel production, ceramics, etc. Industrial furnaces were tested in the context of pure methane combustion with an addition of NH3, up to 5%. Flameless combustion conditions were achieved with a regenerative gas burner system (high regenerative system). The burner consists of four ceramic regenerators allowing for continuous preheating of air, even up to 50 K lower than the temperature of the combustion chamber wall. Constant power of the introduced fuel was kept at 150 kW and the fuel-air equivalence ratio ranged from 0.75 to 0.95. The results have shown a growth of molar fraction of NO in flue gases when NH3 content in the fuel rose. The increase is more significant for the tests with a higher amount of oxygen in the combustion chamber (a lower fuel-air equivalence ratio). An addition of 5% of NH3 into the fuel caused an emission of NO at the levels of 113 ppmv and 462 ppmv (calculated to O2 = 0%), respectively for low and high fuel-air equivalence ratios.

The Effect of Fuel Injection Location on Supersonic Hydrogen Combustion in a Cavity-Based Model Scramjet Combustor

Supersonic combustion experiments were performed using three different hydrogen fuel-injection configurations in a cavity-based model scramjet combustor with various global fuel–air equivalence ratios. The configurations tested were angled injection at 15° to the flow direction upstream of the cavity, parallel injection from the front step, and upstream injection from the rear ramp. Planar laser-induced fluorescence of the hydroxyl radical and time-resolved pressure measurements were used to investigate the flow characteristics. Angled injection generated a weak bow shock in front of the injector and recirculation zone to maintain the combustion as the equivalence ratio increased. Parallel and upstream injections both showed similar flame structure over the cavity at low equivalence ratio. Upstream injection enhanced the fuel diffusion and enabled ignition with a shorter delay length than with parallel injection. The presence of a flame near the cavity was determined while varying the fuel injection location, the equivalence ratio, and total enthalpy of the air flow. The flame characteristics agreed with the correlation plot for the stable flame limit of non-premixed conditions. The pressure increase in the cavity for reacting flow compared to non-reacting flow was almost identical for all three configurations. More than 300 mm downstream of the duct entrance, averaged pressure ratios at low global equivalence ratio were similar for all three injection configurations.

Efficient light-duty engine using turbulent jet ignition of lean methane mixtures

Diesel engines use diffusion-controlled combustion of a high-reactivity fuel and offer high efficiencies because they combine lean combustion with a high compression ratio. For low-reactivity fuels such as gasoline or natural gas, premixed combustion is used, which leads to lower efficiency levels as usually stoichiometric combustion is combined with lower compression ratios. Trying to apply diesel-like process parameters to low-reactivity fuels inevitably leads to problems with classical spark ignition systems as they are not able to establish robust flame propagation for such hard-to-ignite conditions. One possibility to enable fast combustion for diluted mixtures at high pressure levels is to establish ignition in a prechamber and ignite the charge of the main combustion chamber using the turbulent jets exiting the prechamber. In this study, the experimental results of a prechamber-equipped four-cylinder natural gas engine with 2 L displacement are discussed in detail. In the majority of the engine map, auxiliary fueling is used in the prechamber and a global air–fuel equivalence ratio λ is set to 1.7. At full load, a λ of 1.5 is applied without auxiliary prechamber fueling. The experiments show that such a setup is able to achieve brake efficiency levels of above 45% while maintaining peak brake mean effective pressure levels above 20 bar. At high load conditions, cylinder pressure levels at ignition timing achieve more than 80 bar and cylinder peak pressures of around 180 bars occur. The technology proved to enable robust and very fast combustion at comparably low NOxlevels. A remaining challenge for the on-road use of such a technology is the reduction of the methane emissions at lean conditions.

Exploring the potential of ethanol, CNG, and syngas as fuels for lean spark-ignition combustion - An experimental study

In this study, experiments were carried out on a single-cylinder Cooperative Fuel Research (CFR) engine with different fuel-air equivalence ratio (φ) and compression ratio to explore its performance and emissions using four different fuels, E10, natural gas, ethanol, and syngas, at 1200 rev/min and 75 kPa intake pressure. The compression ratio was varied from 9 to 11 for E10 and syngas, and from 9 to 13 for natural gas and ethanol. The combustion characteristics were analyzed on the basis of enabling lean flame propagation. It was found that higher compression ratio resulted in higher engine efficiency and improved lean burn capability for all fuels studied. However, the use of ethanol, natural gas, and syngas helped to extend the lean misfire limit. Syngas enabled combustion at considerably lean operating conditions and achieved the leanest misfire limit. Spark ignition combustion with natural gas showed better lean combustion capability than gasoline and ethanol. Ethanol offered a wider lean limit than E10 and achieved higher fuel conversion efficiency than E10 and natural gas. Combustion with E10 was limited by end gas knock at high compression ratio, which necessitated spark retard and reduced engine efficiency and performance.

An experimental and modeling study on the reactivity of extremely fuel-rich methane/dimethyl ether mixtures

Chemical reactions in stoichiometric to fuel-rich methane/dimethyl ether/air mixtures (fuel air equivalence ratio ϕ = 1–20) were investigated by experiment and simulation with the focus on the conversion of methane to chemically more valuable species through partial oxidation. Experimental data from different facilities were measured and collected to provide a large database for developing and validating a reaction mechanism for extended equivalence ratio ranges. Rapid Compression Machine ignition delay times and species profiles were collected in the temperature range between 660 and 1052 K at 10 bar and equivalence ratios of ϕ = 1–15. Ignition delay times and product compositions were measured in a shock tube at temperatures of 630–1500 K, pressures of 20–30 bar and equivalence ratios of ϕ = 2 and 10. Additionally, species concentration profiles were measured in a flow reactor at temperatures between 473 and 973 K, a pressure of 6 bar and equivalence ratios of ϕ = 2, 10, and 20. The extended equivalence ratio range towards extremely fuel-rich mixtures as well as the reaction-enhancing effect of dimethyl ether were studied because of their usefulness for the conversion of methane into chemically valuable species through partial oxidation at these conditions. Since existing reaction models focus only on equivalence ratios in the range of ϕ = 0.3–2.5, an extended chemical kinetics mechanism was developed that also covers extremely fuel-rich conditions of methane/dimethyl ether mixtures. The measured ignition delay times and species concentration profiles were compared with the predictions of the new mechanism, which is shown to predict well the ignition delay time and species concentration evolution measurements presented in this work. Sensitivity and reaction pathway analyses were used to identify the key reactions governing the ignition and oxidation kinetics at extremely fuel-rich conditions.

The Emission of CO and NOx from Boilers Supplied by a Pellet Under the Influence of Changes in the Air-Fuel Equivalence Ratio

The Emission of CO and NOx from Boilers Supplied by a Pellet Under the Influence of Changes in the Air-Fuel Equivalence Ratio

Multivariate analysis of performance and emission parameters in a diesel engine using biodiesel and oxygenated additive

Rising concerns over environmental and health issues of internal combustion engines, along with growing energy demands, have motivated investigation into alternative fuels derived from biomasses, such as biodiesel. Investigating engine and exhaust emission behaviour of such alternative fuels is vital in order to assess suitability for further utilisation. Since many parameters are relevant, an effective multivariate analysis tool is required to identify the underlying factors that affect the engine performance and exhaust emissions. This study utilises principal component analysis (PCA) to present a comprehensive correlation of various engine performance and emission parameters in a compression ignition engine using diesel, biodiesel and triacetin. The results show that structure-borne acoustic emission is strongly correlated with engine parameters. Brake specific NOx, primary particle diameter and fringe length increases by increasing the rate of pressure rise. Longer ignition delay and higher engine speeds can increase the nucleation particle emissions. Higher air-fuel equivalence ratio can increase the oxidative potential of the soot by increasing fringe distance and tortuosity. The availability of oxygen in the cylinder, from the intake air or fuel, can increase soot aggregate compactness. Fuel oxygen content reduces particle mass and particle number in the accumulation mode; however, they increase the proportion of oxygenated organic species. PCA results for particle chemical and physical characteristics show that soot particles reactivity increases with fuel oxygen content.

Investigation of self-induced thermoacoustic instabilities in gas turbine combustors

The self-induced thermoacoustic instabilities in partially premixed combustors remain a significant challenge which has received a limited research attention. This numerical work investigates the effect of air-fuel equivalence ratio ∅ on exciting thermoacoustic instabilities and its impact on the characteristics of both the acoustic and combustion fields in a partially premixed swirl combustor. For this purpose, three sets of numerical investigations are studied. The first set is a comparison between the present numerical study and previous experimental work considering the normalized combustor wall temperature. The second set of simulations is performed to predict the behavior of the reacting and non-reacting flows with regard to pressure fluctuations, power spectral density, and the sound pressure levels. The third set of simulations considered the effect of the air-fuel equivalence ratio on the acoustics and combustion characteristics. The results reveal that at an equivalence ratio of 0.5, the sound pressure level for the non-reacting and reacting flows are 98 and 118 dB, respectively. It is concluded that the equivalence ratio plays a crucial rule on exciting combustion instabilities at various amplitudes and frequencies. The sound pressure levels increase with increasing in the air-fuel equivalence ratio due to increase the heat release rate.

Evaluation of P. moriformis oil and its blends with diesel fuel as promising contributors to transportation energy

An extensive experimental study was conducted on the 1Z-type CI engine that was running on low, average and high load modes at n = 2000 rpm and used diesel fuel, P. moriformis microalgal oil (PMO100), and their 30% and 70% blends (PMO30, PMO70). Variation of five different parameters of the engine’s operational performance (BSFC, net efficiency, air mass flow, exhaust gas temperature, air-fuel equivalence ratio) and emissions of five chemical compounds (smoke, NOx, HC, CO2, O2) were established. The aforementioned parameters were repeatedly assessed for the engine running at low load conditions, with the advancement or retardation of the start of fuel injection timing (SOI) every 2° of the crankshaft rotation angle from −16° to +4° relative to TDC. The test results revealed that PMO100, PMO30/D70, and PMO70/D30 are more or less equally sensitive to key engine parameters, compared to diesel if proper regulation of SOI is applied. In order to explain the ongoing thermochemical processes within engine cylinders and to support the experimental findings, in-cylinder pressure, in-cylinder pressure rise rate, in-cylinder temperature, mass fraction burnt, in-cylinder temperature rise rate and in-cylinder heat release rate were assesed by using AVL BOOST software that indicated good agreement between simulation and experimental results.