Liquid Phase Penetration Research Articles

Liquid phase penetration sintering of garnet-type solid electrolyte LLZTO

Developing processes for manufacturing all-solid-state batteries that form ionic–conductive interfaces at low temperatures is crucial. In this study, dense ceramics garnet-type lithium ionconductors, Li6.5La3Zr1.5Ta0.5O12 (LLZTO) were prepared at low temperatures (500–800 °C) by reactive liquid phase penetration sintering (LPPS). In this process, pressed precursor oxides (La3Zr1.5Ta0.5O8.75) were exposed to the melt of lithium hydroxide monohydrate (LiOH·H2O). The garnet-type lithium ion conductor prepared by LPPS at 800 °C exhibited a total lithium ion conductivity of 2 × 10−4 S cm−1 at 25 °C. The prepared sample has a garnet crystalline network structure containing amorphous LiOH. The activation energy required for lithium-ion conduction of LLZTO prepared by the LPPS method (0.41 eV) is consistent with that of samples prepared by the conventional solid-phase sintering method at higher temperatures.

Large eddy simulation of spray and combustion characteristics of biodiesel and biodiesel/butanol blend fuels in internal combustion engines

Biofuel is a crucial renewable and environmentally friendly energy source for addressing greenhouse gas emissions and other energy-related issues. Biodiesel and butanol, among alternative biofuels, possess complementary physical and chemical properties, offering multiple possibilities for their use in existing internal combustion engines. However, biodiesel’s distinctly different physical and combustion properties from conventional diesel fuels make its combustion process substantially different. The complex composition of biodiesel presents significant challenges in accurately simulating its spray combustion characteristics. This paper presents a systematic evaluation of six single-component surrogate fuel models and a five-component model for the prediction of biodiesel spray characteristics under various conditions using large-eddy simulation (LES). The results show that single-component surrogate fuel models can only predict the gaseous penetration of biodiesel but not the liquid-phase penetration. A five-component fatty acid methyl ester surrogate fuel model is proposed, demonstrating an accurate simulation of biodiesel spray evaporation characteristics under different conditions. Based on the five-component evaporation model, LES is utilized to examine three strategies of biodiesel/butanol-fueled internal combustion engines: direct injection of pure biodiesel in conventional diffusion-controlled combustion (CDC) engines, direct injection of biodiesel–butanol blend in CDC engines, and biodiesel/butanol reactivity-controlled compression ignition (RCCI) engines. The simulation results are validated against engine experiment results, showing that the five-component model can successfully predict spray and combustion characteristics in internal combustion engines. The RCCI concept can significantly reduce NOx emissions; however, CO and UHC emissions are higher than in the CDC engines due to incomplete combustion in the fuel-lean butanol/air mixture.

Eulerian-Lagrangian simulation and validating experiment of n-butanol/biodiesel dual-fuel impinging sprays

The dual-fuel collision phenomenon is used to realize different concentrations and reactivity stratification in the dual direct injection technique. The present work developed a dual-fuel spray collision model in the computational framework of Eulerian-Lagrangian spray simulation by introducing an additional independent variable, the fuel fraction, to the droplet probability distribution function. This model was used to investigate the macroscopic and microscopic characteristics of n-butanol/biodiesel spray collision, for which experiments were also conducted for validation. Moreover, to investigate the influence of various fuel properties (fuel density, latent heat of evaporation, and vapor pressure) on the spray characteristics, a comprehensive parametric study was conducted. Results show that the simulation result shows a good agreement with the experiment data. As the n-butanol and biodiesel sprays collide, most droplets have a higher mass ratio of biodiesel. Larger SMD is linked to droplet coalescence. Among different fuel properties, the vapor pressure and latent heat of evaporation display a significant impact on the macroscopic characteristics (collision moment and liquid-phase penetration) and microscopic characteristics (droplet number percentage variation of different fuel fractions).

Hollow fiber nanoporous membrane contactors for evaporative heat exchange and desalination

The paper reports the performance of nanoporous polypropylene membrane contactors in water evaporative transfer processes, depending on membrane packing density, flow, and temperature conditions. The membrane evaporator's heat and mass transfer efficiency were evaluated in a wide range of partial pressure gradients and gas phase Reynolds numbers. A protocol for simple evaluation of evaporative heat flux to the heat exchange flux is introduced to reveal the efficiency of mass-to-heat transfer. It has been shown the evaporation efficiency significantly depends on gas flow conditions, increasing at Re ∼ 30 and exceeding 4.6 kg × m-2×h−1 (3.0 kW × m-2×h−1) at the temperature of inlet water of 60 °C. It is achieved by inducing convective flows in the gas phase, which enable the rise of effective heat transfer coefficient for membrane evaporator ∼250 W × m-2×K−1. The attained efficiency is confirmed to originate from heat extraction from the gaseous phase and the evaporation of water from the external surface of fibers. While exhibiting maximal heat flux the regime requires liquid phase penetration through the pores, leading to degradation of the membrane performance in desalination applications. To avoid penetration of ions thin (∼300 nm) graphene oxide coating was deposited onto the internal surface of the nanoporous evaporator, enabling to avoid liquid penetration through the pores and salts crystallization at the external surface, while exhibiting slightly lower performance of the membrane.

STUDY ON THE EFFECT OF THE PRESENCE OF FUEL VAPOR IN THE SURROUNDING GAS ON THE MIXING CONTROLLED VAPORIZATION OF FUEL SPRAY

In different combustion devices, liquid fuel is injected inside the combustion chamber. The liquid fuel spray atomizes, vaporizes, and mixes with the surrounding gas before combustion. The vaporization rate of the injected fuel is very important because it controls the air-fuel mixing and finally the combustion rate. Similar to droplet vaporization, the concentration of fuel vapor in the surrounding gas influences the spray vaporization process. It changes the maximum liquid phase penetration or liquid length (LL) of a vaporizing spray. Hence the liquid length model should consider the ambient fuel concentration effect, but has been ignored up until now. The present work studies the liquid lengths of vaporizing sprays at different fuel vapor concentrations in the surrounding gas. The effects of ambient fuel concentration on heating and vaporization of the spray are analyzed in the context of a mixing controlled vaporization model. The results shows that the fuel concentration in the surrounding gas changes the maximum liquid phase fuel temperature and the specific energy required for vaporization. It is observed that as the ambient fuel concentration effect is ignored in the existing mixing controlled model, it fails to predict liquid lengths when the surrounding gas is mixed with fuel vapor. A modified model is presented where the mass fraction of fuel vapor in the surrounding gas is included in the model. The modified model is able to predict the LL values more accurately when the surrounding gas is mixed with fuel vapor.

Effect of sintering and infiltration conditions on nanoscale dual network SiO2/polymethyl metacrylate composites mimicking human enamel

ObjectiveThe aim of this study was to achieve facile sintering conditions and rapid penetration of organic substances into the structure of sintered silica network on the nano-scale in order to prepare polymer infiltrated ceramic network mimicking human enamel. MethodsStepwise temperature programming (stepwise isothermal firing) was used to create a cohesive ceramic network containing interconnected pores, which is essential to provide polymer/ceramic dual networks. Liquid phase self-penetration, ultrasonic irradiation assisted liquid phase penetration and vapor phase penetration routes were used to infiltrate methyl methacrylate monomers and benzoyl peroxide reagent into the porous silica blocks. ResultsThe use of stepwise isothermal firing route, in comparison with high temperature sintering methods, significantly reduces the time and temperature required for the preliminary preparation of the SiO2 samples and reaching the appropriate interconnected porous structure. The most appropriate method for monomer and oxidant reagents infiltration is to use liquid phase infiltration assisted by ultrasound irradiation of pre-sintered nano-silica blocks. It was found that the amount of infiltrated monomer and oxidizing agent, degree of conversion of the monomer to the polymer and surface hardness of the samples strongly depend on the infiltration route. Clinical significanceThe use of inexpensive silica nanoparticles and low temperature sintering and the use of ultrasound waves to quickly and effectively penetrate methyl methacrylate monomers and increase the polymerization efficiency lead to the preparation of composites with a transparent appearance and mechanical properties similar to human tooth enamel.

Numerical and Experimental Investigations on the Ignition Behavior of OME

On the path towards climate-neutral future mobility, the usage of synthetic fuels derived from renewable power sources, so-called e-fuels, will be necessary. Oxygenated e-fuels, which contain oxygen in their chemical structure, not only have the potential to realize a climate-neutral powertrain, but also to burn more cleanly in terms of soot formation. Polyoxymethylene dimethyl ethers (PODE or OMEs) are a frequently discussed representative of such combustibles. However, to operate compression ignition engines with these fuels achieving maximum efficiency and minimum emissions, the physical-chemical behavior of OMEs needs to be understood and quantified. Especially the detailed characterization of physical and chemical properties of the spray is of utmost importance for the optimization of the injection and the mixture formation process. The presented work aimed to develop a comprehensive CFD model to specify the differences between OMEs and dodecane, which served as a reference diesel-like fuel, with regards to spray atomization, mixing and auto-ignition for single- and multi-injection patterns. The simulation results were validated against experimental data from a high-temperature and high-pressure combustion vessel. The sprays’ liquid and vapor phase penetration were measured with Mie-scattering and schlieren-imaging as well as diffuse back illumination and Rayleigh-scattering for both fuels. To characterize the ignition process and the flame propagation, measurements of the OH* chemiluminescence of the flame were carried out. Significant differences in the ignition behavior between OMEs and dodecane could be identified in both experiments and CFD simulations. Liquid penetration as well as flame lift-off length are shown to be consistently longer for OMEs. Zones of high reaction activity differ substantially for the two fuels: Along the spray center axis for OMEs and at the shear boundary layers of fuel and ambient air for dodecane. Additionally, the transient behavior of high temperature reactions for OME is predicted to be much faster.

Surface layer microstructure and mechanical characteristics analysis of cast iron during milling process under supercritical CO2-MQL

Compacted graphite cast iron (CGI) has a potential application for diesel engines in the automotive industry, but the poor machinability has further impeded the application of CGI. The supercritical CO2-based MQL (ScCO2-MQL), a combination of advantages in both ScCO2 and MQL, has excellent heat dissipation and lubrication performance. The effects of ScCO2-MQL on the surface integrity of CGI at different cutting parameters in the milling process were systematically investigated by experiments and modelling analysis. The variation of microstructure, nano-mechanical properties, and residual stress distribution in machined surface layers of CGI at dry and ScCO2-MQL with different cutting parameters are obtained. To further reveal the underlying reasons for cooling and lubrication effects of ScCO2-MQL in the milling of CGI. The cooling mechanism of ScCO2-MQL was explained by the introduction of the forced heat convection and coolant boundary layers. The heat transfer model of ScCO2-MQL was established. The temperature distribution along the tool surface is presented considering similarity theory analysis. The lubrication mechanisms are also revealed by the liquid phase penetration model. The results verified that the ScCO2-MQL, by the introduction of higher compressive stress amplitude/depths and large hardened layers, can improve anti-fatigue characteristics and service performance of the CGI component in the automotive industry.

Adsorption mechanism of oxide inclusions by microporous magnesia aggregates in tundish

The microporous refractory with low thermal conductivity shows a promising application prospect as tundish lining. In this study, the interactions between microporous magnesia aggregates and oxide inclusions in steel were explored. The experimental results and thermodynamic calculation show that the interaction process of microporous magnesia aggregates and oxide inclusions at high temperature can be divided into dissolution, reaction and post-reaction. The microporous magnesia aggregates can absorb the inclusions in steel by reaction and liquid phase penetration. The microporous magnesia aggregates have a strong adsorption for Al 2 O 3 and TiO 2 . Moreover, the microporous magnesia aggregates mainly absorb SiO 2 by penetration, but excessive SiO 2 will lead to the serious corrosion of microporous magnesia aggregates.

The Corrected Distortion model for Lagrangian spray simulation of transcritical fuel injection

In this work, we present a detailed implementation and validation of the droplet modeling framework proposed by Dahms and Oefelein (2016) into the engine commercial CFD software CONVERGE using the User Defined Function (UDF) interface. The model accounts for the nonlinear deformation and oscillation experienced by liquid spray droplet injected into high pressure and temperature. Lagrangian spray simulations of Engine Combustion Network (ECN) Spray A are performed. Model validation against standard experimental measurements of liquid velocity, vapor mixture fraction is conducted. To perform more rigorous model validation, new experimental measurements based on Diffused Back Illumination (DBI) are introduced. The new measurements are processed for Projected Liquid Volume (PLV), which offers as close as possible one-to-one model validation for liquid penetration while offering new insights into the spray physics. Comparison with a One-D model based on adiabatic mixing theory by Siebers (1999) and Desantes et al. (2007) are also conducted. Through these model validation exercises, it is shown that the new framework improves liquid-phase penetration predictions, following a tendency for enhanced evaporation, compared to the standard approach for both Reynolds Average Navier Stokes (RANS) and Large Eddy Simulation (LES). At the liquid length, maximum mixture fraction values predicted by the new approach are in good agreement those of an adiabatic mixing model. Qualitative analysis of the spray behaviors during the early stage of the injection process reveals that the proposed framework predicts significant increase in droplet evaporation rate with lower drop drag compared to the current standard approach.

Gasoline spray characteristics using a high pressure common rail diesel injection system by the method of laser induced exciplex fluorescence

The liquid and vapor phases of gasoline sprays were investigated using a common rail diesel injection system in a constant volume vessel by laser induced exciplex fluorescence (LIEF) and compared with diesel sprays. The effects of injection pressure and ambient pressure on gasoline sprays were measured under evaporating conditions. The results reveal that: the liquid phase penetration has a little change as the fuel is injected, while the vapor phase penetration increases constantly with obvious branch-like structures generated at the downstream vapor phase. The spray volume and mass of entrained gas both increase roughly linearly versus the mass of injected fuel. Compared with diesel sprays in similar conditions, gasoline sprays display a significantly shorter liquid penetration, while a smaller difference between the vapor penetration lengths of gasoline and diesel sprays is observed. The maximum equivalence ratio of gasoline sprays is still more than 2 at selected conditions. As the ambient pressure increases, the penetration lengths of liquid and vapor phases both reduce, and the mean equivalence ratio also decreases with a drop of spray volume. Conversely, the mass of entrained gas rises continually. With the increase of injection pressure, the liquid phase penetration length maintains almost no change. However, the vapor penetration length shows a declined trend during the injection pressure rise at iso-injected fuel mass condition. The spray volume and mass of entrained gas give a slight reduction when the injection pressure enhances. Oppositely, the mean equivalence ratio presents an increased tendency with similar mass of injected fuel.

Experimental study on spray characteristics of six-component diesel surrogate fuel under sub/trans/supercritical conditions with different injection pressures

The purpose of this study is to explore the spray characteristics of six-component diesel surrogate fuel under sub/trans/supercritical conditions with different injection pressures and provide a reference for numerical simulation. The experiments were conducted in a constant volume chamber. The liquid- and vapor-phase spray images were captured by backlight illumination and schlieren imaging technology, respectively. Some macroscopic parameters were obtained and analyzed, such as spray structure, spray penetration, liquid-core index, spray cone angle, gas entrainment mass, spray perimeter, spray area, and spray irregularity. Results show that the variation law of the liquid-phase penetration shows opposite trend with injection pressure depending on ambient temperature. The liquid-phase spray is more stable with a smoother surface under supercritical conditions. The spray cone angle is mainly related to ambient temperature and pressure. The gas entrainment mass increases with decreasing ambient temperature or increasing ambient pressure. When the ambient pressure is twice fuel’s critical pressure, the liquid-phase spray irregularity is smaller, but an increase in injection pressure can further increase the spray irregularity. When the ambient temperature is higher than the critical temperature, increasing the injection pressure or ambient pressure is conducive to increasing the ratio of pure vapor-phase spray and improving the spray characteristics.

The Effect of Elliptical Diesel Nozzles on Spray Liquid-Phase Penetration under Evaporative Conditions

Elliptical diesel nozzles affect the fuel–air mixing process, and thus combustion and exhaust emissions. Experiments were conducted to study biodiesel spray liquid-phase behaviors for elliptical and circular nozzles through the Mie-scattering method under evaporative conditions. Based on the measurements, the results show that the elliptical nozzle spray liquid-phase penetration is smaller than the circular one under steady-state conditions. The deformation and the axis-switching behaviors of the elliptical jet are helpful in accelerating the breakup of the liquid core. Moreover, the injection pressure has little impact on the penetration of the liquid-phase spray for either geometrical orifice. Additionally, increasing the ambient temperature can reduce the penetration of liquid-phase spray, because an increase in temperature increases the rate of evaporation. The differences in steady liquid-phase penetration between circular and elliptical sprays decrease as the ambient temperature increases. Additionally, increasing the backpressure can decrease the liquid-phase penetration. The differences in steady liquid-phase penetration between circular and elliptical nozzles are reduced with the increase in backpressure, probably due to the axis-switching and deformation behaviors of the elliptical jet being restrained under high-backpressure conditions. Finally, the application of an elliptical orifice is beneficial for decreasing the spray liquid-phase penetration, and thus avoiding the fuel impingement in small engine combustion chambers. The lower liquid-phase penetration for elliptical spray indicated higher fuel and air mixture quality, which is helpful for reducing the diesel engine exhaust soot emissions.

Assessment of n-pentanol additive and EGR rates effects on spray characteristics, energy distribution and engine performance

Owing to the high viscosity of biodiesel, it is not suitable for atomization and volatilization, and it has limitations in reducing emissions. As an alternative fuel with high oxygen content, n-pentanol mixed with biodiesel can reduce viscosity and improve volatility. Therefore, in this work, assessment of n-pentanol additive and EGR rates effects on spray characteristics, energy distribution and engine performance were investigated. The test fuels were pure diesel (D100), a mixture of 20% biodiesel and 80% diesel (BD20), and 20% n-pentanol, 16% biodiesel, and 64% diesel (BDP20). The results indicated that the addition of n-pentanol shortened the liquid phase penetration (LPP) of the mixed fuel and decreased the liquid phase spray cone angle (SCA); at the same time, the addition of n-pentanol could reduce the total particle mass concentration (TPMC) and the total particle number concentration (TPNC), and also reduce the energy loss of Soot and THC emissions, while the brake thermal efficiency (BTE) was not much different from D100 and BD20; further, with the EGR rate increased, the peak of the heat release rate (HRR) of BDP20 increased, and the trade-off relationship between NOx-Soot was improved.

Experimental and analytical study on liquid and vapor penetration of high-reactivity gasoline using a high-pressure gasoline multi-hole injector

Spray penetration length is an important parameter which is of great interest to both experimentalists and modelers. As it affects engine efficiency and emissions, measurement and prediction of spray penetration can significantly benefit engine optimization under various operating conditions. In this study, penetration length was investigated in a pre-burn constant volume combustion chamber using a gasoline multi-hole injector with high reactivity gasoline-like fuel designed explicitly for gasoline compression ignition (GCI) engines. Diffused back illumination (DBI) and shadowgraph were implemented for liquid and vapor phase penetration measurements, respectively. Different pre-burn gas mixtures are compared to investigate the influence of ambient gas properties on gasoline spray penetration under evaporating conditions. The liquid penetration under the gas composition of higher molecular weight tends to be longer. However, the vapor penetration showed insignificant effect under different gas compositions. Ambient gas temperature and gas composition were found to be an essential parameter for liquid phase penetration. Pressure difference was found to affect the vapor penetration length while its influence on liquid phase steady state penetration length at high ambient gas temperature is marginal. Statistical analysis was performed for both liquid and vapor phase penetration lengths, and a prediction model was developed with good agreement to the data under all test conditions.

Macroscopic non-reacting spray characterization of gasoline compression ignition fuels in a constant volume chamber

Recently, gasoline compression ignition (GCI) engines have become a topic of interest due to its benefits in high thermal efficiency and low emissions. Combustion in GCI engines is highly governed by the fuel stratification which is strongly associated with the spray characteristics like penetration length. Researchers have proposed both theoretical, and regression models for liquid penetration length of diesel and gasoline direct injection (GDI) spray at non-evaporating conditions. However, there are no models for gasoline sprays at elevated ambient gas temperatures, pressures, and injection pressures in literature. This research gap needs to be bridged, as it is crucial for GCI engine technology. In this study, penetration length was investigated using a high-pressure custom-made multi-hole gasoline injector. High reactivity low carbon fuel (RON 77), designed explicitly for GCI engines, and E10 certification fuel (RON 91) were used and compared. Diffused back illumination (DBI) and shadowgraph were implemented for liquid and vapor phase penetration measurement, respectively. It was found that the spray characteristics of high reactivity fuel were similar to E10 certification fuel under non-reacting conditions. Statistical analysis was performed for both liquid and vapor phase penetration lengths, and empirical models were developed with good agreements to the experimental data under high ambient gas pressure and temperature relevant to GCI engine operating conditions using GCI fuels at higher injection pressures. A ‘separation point’ was defined for the liquid phase after which it reaches a steady state, and it was demonstrated to be different from the ‘breakup time’ found in the literature.

Spray performance of air-assisted kerosene injection in a constant volume chamber under various in-cylinder GDI engine conditions

The performance of kerosene spray from an air-assisted system was investigated in a constant volume chamber by backlit imaging and shadowgraph technologies over various chamber pressures, temperatures, and fuel amount. The results show that the penetration decreases with the increase in the chamber pressures from 0.5 bar to 3.5 bar due to the reduction in the differential pressure between the air/fuel interface and ambience and the rise in the resistance to penetration as well. Liquid-phase penetration increases with an increase in temperature from 400 K to 500 K both at 1.0 bar and 3.0 bar for decreasing density of ambient gas. When ambient temperature was increased at 1.0 bar, there was no significant change in the vapor penetration. Therefore, increasing ambient temperature by internal EGR cannot reduce wall impingement when GDI engines fueled with kerosene. Furthermore, liquid-phase penetration decreases with the increase in fuel amount, while at the front end of spray the cross-sectional area increases since the spray is increasingly disturbed by the ambient gas.

Effects of the turbulence model and the spray model on predictions of the n-heptane jet fuel–air mixing and the ignition characteristics with a reduced chemistry mechanism

Reynolds-averaged Navier–Stokes simulations with an improved spray model and a realistic chemistry mechanism are performed for turbulent spray flames under diesel-like conditions in a constant-volume chamber. Comprehensive numerical analyses including two turbulence models (the renormalisation group k– ε model and the standard two-equation k– ε model) with different model coefficients are made. The distribution of the fuel mixture fractions is a very important factor affecting the combustion process. In this study, we also use the entrainment gas-jet model, modifications of the the spray model coefficient and two turbulence models to investigate extensively the influence of the gas-jet theory model on the fuel–air mixture process. First, a non-reacting case is validated by comparing the liquid-phase penetration and the vapour-phase penetration and also the mixture fractions at different axis positions. Second, approriate methods are confirmed according to accurate mixture fraction distributions to validate the combustion process. Because of the large number of species and reactions, the calculation of chemically reacting flows is unaffordable, particularly for three-dimensional simulations. Hence, the dynamic adaptive chemistry method for efficient chemistry calculations is extended in this work to reduce the computational cost of the spray combustion process when a reduced chemistry mechanism is used. The results show that, in the evaporation case, the gas-jet theory model can be used to obtain a relatively accurate fuel vapour penetration length with different influential factors and that improved numerical methods can effectively reduce the mesh dependence for the spray evaporation process. It is demonstrated that the Schmidt number Sc and the turbulence models significantly influence the mixture fraction distribution. Very good agreement with available experimental data is found concerning the ignition delay time and the flame lift-off length for different oxygen concentrations owing to the accurate fuel mixture fraction.

Modeling of the primary rearrangement stage of liquid phase sintering

The dimensional variations during the rearrangement stage of liquid phase sintering could have a detrimental effect on the dimensional tolerances of the sintered product. A numerical approach to model the liquid phase penetration into interparticle boundaries and the accompanied dimensional variations during the primary rearrangement stage of liquid phase sintering is presented. The coupled system of the Cahn–Hilliard and the Navier–Stokes equations is used to model the penetration of the liquid phase, whereas the rearrangement of the solid particles due to capillary forces is modeled using the equilibrium equation for a linear elastic material. The simulations are performed using realistic physical properties of the phases involved and the effect of green density, wettability and amount of liquid phase is also incorporated in the model. In the first step, the kinetics of the liquid phase penetration and the rearrangement of solid particles connected by a liquid bridge is modeled. The predicted and the calculated (analytical) results are compared in order to validate the numerical model. The numerical model is then extended to simulate the dimensional changes during primary rearrangement stage and a qualitative match with the published experimental data is achieved.

Application of jet propellant-8 to premixed charge ignition combustion in a single-cylinder diesel engine

The aviation fuel, jet propellant-8, was applied to premixed charge ignition combustion as well as conventional combustion in a single-cylinder diesel engine and was compared with diesel fuel. The engine performance and emissions were tested with and without exhaust gas recirculation under two operating conditions. The liquid- and vapor-phase penetration of diesel fuel and jet propellant-8 were also compared by Mie-scattering and Schlieren method under evaporating conditions using a constant-volume chamber. It was observed that jet propellant-8 exhibited slightly longer vapor-phase penetration and evidently shorter liquid-phase penetration compared with diesel fuel due to the lower distillation temperature and density of jet propellant-8. However, despite the faster evaporation rate of jet propellant-8, it was found that the ignition delay with jet propellant-8 was 2–3 crank angle degrees longer than that with diesel fuel due to its lower cetane number. This result was consistent for all operating conditions and combustion regimes. Jet propellant-8 also showed lower nitrogen oxides (NOx) and smoke emissions for both combustion regimes under the low-load condition because of locally leaner air–fuel mixture caused by longer ignition delay, higher volatility, and lower aromatic contents. As the engine load increased, jet propellant-8 emitted more NOx under conventional combustion regime due to the more vigorous premixed burn phase compared with diesel fuel. With exhaust gas recirculation, jet propellant-8 showed an improved trade-off relationship between NOx and smoke emissions for both combustion regimes due to its better evaporation characteristics and lower aromatic contents. Premixed charge ignition combustion with jet propellant-8 emitted lower smoke than conventional combustion with jet propellant-8 under near-zero NOx level.