Homogeneous Temperature Distribution Research Articles

Comparative Evaluation and Multi-Objective Optimization of Cold Plate Designed for the Lithium-Ion Battery Pack of an Electrical Pickup by Using Taguchi–Grey Relational Analysis

It is aimed to minimize carbon emissions and the spread of electric vehicles is supported for a more sustainable future. To increase the safety and life of these vehicles, cooling systems are added and developed to their energy storage systems. The aim of this study is to design and optimize the cooling plate for the lithium-ion battery pack used in a lightweight commercial electrical vehicle. Multi-objective optimization using Taguchi–grey relational analysis was performed by considering maximum temperature, the standard deviation of temperature, and pressure drop for the design of the cold plate. Channel number, channel height, and mass flow rate values were determined as parameters to be examined, and three different levels were selected for each parameter. Analysis was performed using water and 25% and 50% ethylene glycol–water solutions, which can work under sub-zero environmental conditions, employed as cooling fluid. It is shown that increasing the ethylene glycol ratio in the coolant allows it to work in colder environmental conditions, it is relatively worsening thermal performances in the cold plate applications. A new empirical correlation is proposed to predict the Nusselt number for the three coolants under all geometric and operating conditions considered in this study. Statistical analysis shows that the number of channels is the most effective parameter for the relatively low and homogenous temperature distribution on the cold plate surface. A sensitivity analysis was performed for Reynolds number ranges from 2500 to 15,000 using the optimum configurations of the three coolant fluids. It is shown that the same cooling effects could be obtained by using 1.56 times and 2.66 times more mass flow rates for 25% and 50% ethylene glycol–water solutions, respectively, compared to the water. However, rising mass flow rates result in a significant increase in the required pumping power.

Comparative analysis of ammonia/hydrogen fuel blends combustion in a high swirl gas turbine combustor with different cooling angles

In this study, numerical modeling of ammonia-hydrogen fuels (10%–50%) in a turbulent eddy gas turbine combustion chamber with different cooling angles (15, 30, 45) have been performed by using a computational fluid dynamics code. It has been observed that the maximum temperature levels in the combustion chamber decrease with the addition of ammonia and the flame moved towards the exhaust of the combustion chamber because of the lower burning rate of ammonia in the regions where the flame occurs. Although the addition of ammonia in the combustor increases the NOx levels in the flame core rapidly. The 45° provides a more homogeneous temperature distribution compared to other conditions with 15–30° inclination angles at the outlet. As a result, it can be concluded that ammonia-hydrogen blended fuels have a substantial possibility as an option and sustainable fuel in terms of combustion performance.

Experimental dynamic load cycling and current density measurements of different inlet/outlet configurations of a parallel-serpentine PEMFC

Proton-exchange membrane fuel cells (PEMFCs) in the transport sector require specific design and durability, and stable and reliable performance under varying cycling loads. In this study, experimental dynamic load cycling (DLC) tests and current density mapping (CDM) measurements of local current densities and temperatures were performed for different inlet/outlet configurations of reactants in a parallel-serpentine PEMFC. Results were analyzed in terms of the polarization and power curves and the DLC tests, indicating that the Inverse Hydrogen Flow configuration performed best. However, the differences with respect to the other inlet/outlet configurations (Normal Flow, Inverse Air Flow and Inverse Flow) were not significant with maximum relative voltage and power densities differences below 5% in the polarization and power curves. Also results of the experimented inlet/outlet configurations during the DLCs were similar, with maximum differences in terms of energy during the cycle below 10% comparing the best configuration (Inverse Hydrogen Flow) with the worst. CDM measurements showed an inverse bell-shaped distribution with higher current density values in the external part of the bipolar plate and lower values in the central part and a highly homogeneous temperature distributions in all configurations.

Experimental study and numerical simulation of a floor heating system in a three-dimensional model: Parametric study and improvement

In recent years, the installation of underfloor heating systems has increased considerably in many countries, due to their ability to be connected to a solar thermal collector in order to benefit from clean and renewable energy. This promising technology allows for reduced energy consumption, achieves a higher level of comfort, and ensures a more homogeneous temperature distribution than conventional heating systems. A huge loophole is detected in research works concerning the three-dimensional numerical modelling of the thermal behavior of underfloor heating by COMSOL Multiphysics software. The present study aims to reduce these knowledge gaps and to analyze the thermal behavior of the direct solar floor numerically and experimentally under the specific climatic conditions of Casablanca, Morocco. Visualize the thermal behavior of the underfloor heating system and the heating circuit as a 3D model using COMSOL Multiphysics software, based on the finite element method by investigating the influence of various design and operational parameters to select the best parameters that guarantee thermal comfort in the case of installing this heating system in traditional bathrooms.The results obtained by numerical simulation are then compared with those of the experimental measurements in order to verify the validity of the numerical model. The average deviation between the simulated and measured surface temperatures is approximately 1.04%, while the deviation in pipe temperature is around 3.13%, which shows a very good agreement between the numerical and experimental results. In addition, the results of the parametric study indicate that the key elements for enhancing the floor heating system are primarily a floor covered by tile with a minimum thickness of 5 mm, a pipe spacing of approximately 15 cm, a PER pipe diameter of 16/20 mm, and a thermal insulation layer with a thickness of 50 mm made of XPS or polystyrene. The incorporation of these improvements in the standard model ensures a surface temperature within the thermal comfort range of a less warm bathroom, approximately 34.13 °C, and a high heat flux emitted at the surface around 502.07 W compared to the standard model. In the literature, it was found that the comparison of architectural characteristics of direct solar floors receives minimal attention, with most studies only comparing systems in terms of thermal comfort or energy efficiency. In this study, the analysis and interpretation of the results obtained can be used to help engineers and designers select the type and dimensions of the best materials for heating floors installed in traditional bathrooms in Morocco.

2D-axisymmetrical modeling and experimental study of hydrogen absorption in copper coated metal hydride

The storage of hydrogen in metal hydride reactors is examined experimentally and numerically in this paper. In this respect, as-received LaNi5 powders are coated with different amounts of copper by using copper sulphate solution to accelerate the hydrogen charging processes. The thermal conductivity of the copper-coated storage material is found to reach up to 8 times of the uncoated powders. A two-dimensional axisymmetric model regarding complex heat and mass transfer occurring during hydrogen charging process in metal hydride reactors is numerically solved at macro level. The developed model is validated by using experimental data related to the amount of hydrogen stored and the reactor temperatures. In accordance with the experimental results, the simulation results show that more homogenous temperature distribution in the reactor can be obtained with the copper coating due to improved thermal properties. Moreover, charging time is also improved by the copper coating. However, since the reactor is loaded with coated/uncoated LaNi5 powders at the same weight of 65 g, the total amount of hydrogen stored decreases with the copper coating due to reduced amount of LaNi5.

Numerical investigation of thermal and flow characteristics of impinging synthetic jet with different nozzle geometries at low nozzle-to-plate distances

Synthetic impinging jets are potentially useful techniques in electronic cooling. In this paper, the fluid and heat transfer characteristics of impinging synthetic jets were analyzed numerically by using circular, square, and rectangular shaped nozzles under short nozzle-to-plate spacing and actuation frequencies. A three-dimensional model was built to investigate dimensionless nozzle-to-plate distance (H/D = 0.10 – 1.00), Reynolds number (Re = 1810–4140), and excitation frequency (f = 250 – 500 Hz) effects on flow and heat transfer for a single jet. Firstly, the results were compared with experimental results from the literature, and a fair agreement has been obtained. Afterwards, instantaneous images of velocity contours and streamlines were presented to show the flow characteristics. By using simulation results, time-averaged Nu number and time and area-averaged Nu number (Nuavg) values were presented. Finally, a correlation was proposed for different cases to describe the variation in Nuavg. It was observed that a more homogenous temperature distribution on the impingement surface could be obtained by decreasing H/D and increasing Re number, whereas by increasing the nozzle-to-plate distance, lower temperature values could be obtained at the impingement region. Nuavg is almost unaffected from the nozzle geometry under the present investigated conditions. Higher local Nu number values were obtained for 0.50 = H/D around the impingement region. On the other hand, for 0.10 ≤ H/D < 0.50, a more uniform temperature distribution was obtained which leads to higher Nuavg. This study provides significant knowledge about the flow and heat transfer characteristics of synthetic impinging jets at low nozzle-to-plate distances, which could provide guidance in the thermal design procedure of electronic components.

Effective Thermal Conductivity of Lithium‐Ion Battery Electrodes in Dependence on the Degree of Calendering

The thermal conductivity represents a key parameter for the consideration of temperature control and thermal inhomogeneities in batteries. A high‐effective thermal conductivity will entail lower temperature gradients and thus a more homogeneous temperature distribution, which is considered beneficial for a longer lifetime of battery cells. Herein, the impact of the microstructure within the porous electrode coating obtained by different compression rates and its thermal contact to the current collector is investigated as both factors significantly determine the overall conduction through the electrode. The effective thermal conductivity of two graphite anodes and two lithium nickel manganese cobalt oxide cathodes is evaluated at different compression rates. It is found that the thermal conductivity does not have a monotone dependence on the porosity with changing compression rates. The results show a strong correlation with the adhesion strength, thus a significant impact of the thermal contact resistance between the coating and current collector is assumed.

Investigation of the Structural Dependence of the Cyclical Thermal Aging of Low-Voltage PVC-Insulated Cables

The increasing penetration of distributed generation sources in low-voltage distribution grids, electric vehicles, and new appliances from the consumer side can generate short repetitive overloads on the low-voltage cable network. This work investigates the change in the dielectric properties of low-voltage cable insulation caused by short-term overloads, examining how the cable structure affects the dielectric characteristics of the cable specimens in the case of cyclic short-term thermal aging. PVC-insulated low-voltage cable samples were exposed to an accelerated aging test in a temperature-controlled oven after changing their structures by removing different layers. Three aging cycles, each of six hours, were applied to the samples. After each cycle, the tan δ and capacitance were measured by an Omicron DIRANA Dielectric Response Analyzer in the laboratory at room temperature 24 ± 0.5 °C. Furthermore, the polarization and depolarization currents were also studied. The results show that changing the cable structure impacts the dielectric parameters; in particular, the effect of the belting layer is significant. From the point of view of aging, the PVC belting layer protects the diffusion of the plasticizers of the inner structure. The findings of the study show that an asymmetric aging phenomenon can be observed in different polymeric components of the cables, even though the cables were aged in an air-circulated oven ensuring a homogeneous temperature distribution in the samples.

In situ tensile behavior of hybrid carbon and glass fibers reinforced PEEK laminates: Isothermal or fire testing conditions

This work aims at investigating the thermo-mechanical coupling under critical temperature conditions in hybrid carbon/glass fibers reinforced Poly Ether Ether Ketone (PEEK) laminates. Two testing conditions have been considered: (i) isothermal and (ii) fire condition. A tensile loading was applied in homogeneous and isothermal temperature distribution (Room temperature – 350 and 500 °C) by means of a high-temperature furnace to quantify the influence of temperature on the mechanical response and properties. Regarding the fire conditions, a one-of-a-kind bench-scale fire test combining an in situ tensile mechanical loading and a kerosene burner (a flame temperature of 1100 °C ± 80 °C and a heat flux of 116 kW/m2 ± 10 kW/m2) has been designed and instrumented to induce anisothermal temperature conditions. This prototype allows the evolution of various physical quantities to be tracked as a function of the flame exposure time (5-10-15 min). These include temperature, loss of mass, deformation, stress, which are fundamental for understanding the mechanisms brought into play. The decrease of the tensile properties under isothermal conditions is −38% ± 0.6% (axial stiffness) and −54% ± 0.3% (axial strength) with respect to the values obtained at room temperature. The tensile response under fire is similar to the one obtained in isothermal conditions at 500 °C. The creep behavior of CG/PEEK laminates was also investigated with different boundary conditions (with or without a protective shield reducing the delirious effect of flame in terms of damages within the laminates). Compared to virgin specimens, the residual tensile mechanical properties significantly decrease as a function of the flame exposure time (5-10-15 min): 30% ± 1.1% and −55% ± 1.6% in axial stiffness and strength, respectively.

Morphology Control of Metal Pool and Eutectic Carbides in Electroslag Remelted M2 HSS with an External Axial Static Magnetic Field

This study investigates the influence of a superimposed axial static magnetic field (ASMF) on the morphology of metal pool and eutectic carbides (ECs) in electroslag remelted M2 high-speed steel (HSS). The application of ASMF caused the metal pool to become shallower, and the solidified structure to expand axially, along with finer (i.e., more uniformly distributed and crystallographically oriented) ECs. Lorentz force-driven unidirectional circulation in slag pool was the primary cause of the metal pool’s morphological adjustment; this resulted in a more homogenous temperature distribution in slag pool. Thus, the heat transfer from the slag pool to the metal pool became more uniform, creating a metal pool that is shallower. Additionally, local solidification time (LST) became shorter, while the number of (Ti, V)N-Al2O3 inclusions serving as heterogeneous nuclei for EC formation increased due to ASMF, enabling finer EC with more crystallographic orientations in ESR ingots.

Burner-heated dehydrogenation of a liquid organic hydrogen carrier (LOHC) system

For a hydrogen-based economy, safe and efficient hydrogen storage is essential. Compared to other chemical hydrogen storage technologies, such as ammonia or methanol, liquid organic hydrogen carrier (LOHC) systems allow for a reversible storage of hydrogen while being easy to handle in a diesel-like manner. In our contribution, we describe for the first time the successful utilization of the exhaust gas enthalpy of a porous media burner to directly supply the dehydrogenation heat for a kW-scale dehydrogenation of the hydrogen-rich LOHC compound perhydro dibenzyltoluene (H18-DBT). Our setup demonstrates the dynamics of the dehydrogenation unit at a realized maximum hydrogen power of 3.9 kWth, based on the lower heating value of the released hydrogen. For the intended applications with fluctuating hydrogen demand, e.g. a hydrogen refueling station (HRS) or stationary heating in buildings, a dynamic hydrogen supply from LOHC is important. Methane, e.g. from a biogas plant, is utilized in our scenario as a fuel source for the burner. Hydrogen is released within 30 min after cold start of the system. The dehydrogenation unit exhibits a power density relative to the reactor volume of about 0.5 kWtherm l−1 based on the lower heating value of the hydrogen and a catalyst productivity of up to 0.65 gH2 gPt−1 min−1 for hydrogen release from H18-DBT. An analysis of the by-products and reaction intermediates shows low by-product formation (e.g. maximum 0.6 wt.-% for high boilers and 0.9 wt.- % for low boilers) and uniform distribution of intermediates after the reaction. Thus, a relatively homogeneous temperature distribution and a uniform LOHC flow in the reaction zone can be assumed. Our findings illustrate the dynamics (heating rates of about 10 K min−1) and performance of direct heating of a release unit with a burner and represent a significant step towards LOHC-based hydrogen provisioning systems at technically relevant scales.

Numerically efficient two-step CFD simulation model of flow regime and heat transfer for hot water shower sterilizers

This work was carried out to create a numerically efficient validated simulation model for Hot Water Shower (SWS) sterilizers. The goal of the work was to achieve a more homogeneous temperature and water distribution inside the sterilizers developed in the future. A lab-scale test bench of an SWS sterilizer with a configurable water volume flow rate and temperature was designed to validate the Computational Fluid Dynamics (CFD) model that was created. The heating and cooling phases at water volume flow rates of 20 and 40m3/h per m2 spraying surface were analyzed. Additionally, the flow and film regime were studied. The CFD model was split into two simulation steps to significantly improve the numerical efficiency. The novel two-step approach developed is computationally 1800 times faster as compared with a complete sterilization cycle than a state-of-the-art approach. The simulated temperature of the test load was in good accordance with the experimental measurements. The flow regime was largely accurately replicated. Overall, the created validated CFD model is suitable for upscaling to an industry-sized SWS sterilizer due to its numerical efficiency.

Effects of split diesel injection strategies on combustion, knocking, cyclic variations and emissions of a natural gas-diesel dual fuel medium speed engine

Accelerated by the harms and depletion risk of fossil fuels, transition to low-carbon or renewable fuels have become an urgent need for combustion engines to decarbonize transport sectors. Natural gas-diesel dual-fuel combustion is a promising method to achieve these goals by allowing the usage of natural gas in diesel engines. However, this concept has drawbacks of low combustion efficiency, high unburned hydrocarbon (HC) emissions and high cyclic variations at low engine loads. These drawbacks hinder the benefits of dual-fuel such as low NOx and soot emissions. To find solutions to these drawbacks, split diesel injections with variable injection timings and mass split ratios (ratio of first injection diesel mass to total diesel mass) were investigated experimentally and numerically on a medium speed marine engine at low load using constant natural gas and diesel amounts.Experimental results of the split injection were compared to single injection dual-fuel and conventional diesel operation. Single injection case resulted in slightly lower HC emissions and cyclic variations and higher NOx emissions than split cases in a narrow injection timing interval. Apart from that, split injections increased combustion efficiency and decreased cyclic variations in a broader timing interval. For split cases, early first injection timing prevented high premixed heat release peak, suppressed NOx emissions and knocking. Especially, using 70% split ratio with retarded second injections increased combustion efficiency, decreased knocking level and provided simultaneous reduction of HC and NOx emissions compared to lower split ratio cases. In short, despite not giving the minimum values at all conditions, split injection showed potential to find a remedy to high HC emissions and cyclic variations issues by keeping robust operation in a wider injection timing interval.The numerical results support the experiments in which better combustion and decreased HC emissions are attained using sufficiently early diesel injections. Simulations show that, compared to late single injection, early single injection dual-fuel case enables more homogeneous temperature distribution and better oxidization of methane near the cylinder wall and central region above the piston crown. Besides, split injection shows improved methane oxidation near the cylinder wall and inside top-land crevice volume.

Highly Conductive Cellulose Strain Sensor with Excellent Negative Resistance Variation and Joule Heating Property

The rational design of a wearable strain sensor with heating property has attracted great interest. In this study, a flexible conductivity hierarchical cellulose strain sensor (MX@Ag@CY) with heating property was fabricated via in situ formation of silver nanoparticles (Ags) on cotton yarn (CY) and subsequent dip-coating with MXene (MX). Ags coupled with MX coating endowed the cotton yarn with a high conductivity, where the resistance of the optimized composite MX@Ag0.47@CY was about 22 Ω/cm. Compared with the previously reported strain sensors, the woven MX@Ag0.47@CY fabric strain sensor showed a distinctive negative resistance variation, wherein it showed an enhanced conductivity with the increased strain owing to its unique architecture. The woven MX@Ag0.47@CY fabric strain sensor exhibited a repeatable response and displayed long-term stability in the strain range of 0–55%. In addition, the strain sensor demonstrated great detectability on large-scale human movements when directly attached to the elbow, wrist, or knee. Furthermore, when MX@Ag0.47@CY served as a heater (at an applied DC voltage of 6 V), it presented high heating temperature (92.4 °C), homogeneous temperature distribution, low operation voltage (1–6 V), and excellent thermal stability even under strain.

Enclosure Fire with Time-Dependent Changes in Ventilation Factor and Geometry—Field Model Parameters Analysis

The fire scenarios currently used for structural fire design are based on traditional methods that derive from the extrapolation of existing fire test data. The traditional “furnace” geometry test allows a good circulation of the fire gases and a relatively homogeneous temperature distribution throughout the enclosure. These conditions are different from what is observed in real-situation fires. As a result, the need for a field model for an enclosure fire has increased significantly, and appropriate deterministic models are necessary for fire safety engineering. The effects of different strategies involving the opening of doors and windows with changes in the enclosure’s geometry were observed to gain an insight into the impact of how ventilation and geometry influence changes during the development of a fire. This article presents and discusses the results of the field model compared with similar tests and experiments described in the technical and scientific literature. Generating data using a field model reduces experimental costs and facilitates sensitivity analyses of the parameters of problems.

Numerical analysis of the fluid flow and heat transfer of a hybrid PV-thermal collector and performance assessment

In recent years, new materials and absorber configurations have been proposed to improve the performance of hybrid photovoltaic-thermal (PV-T) collectors. This work analyses the fluid flow and the energy performance of an uncovered water-based PV-T collector with a roll-bond thermal absorber. A detailed CFD model was developed and the results were compared with the experimental performance features provided by the PV-T manufacturer. The fluid flow results show uneven flow distribution among the roll-bond microchannels which leads to areas with larger PV cell temperatures and thus a lower electricity generation. The PV-T collector layers were also modelled using the energy transfer equations layer-by-layer. The model was run for several water inlet temperatures and water flow-rates to obtain the thermal performance curve. The results show that the electrical efficiency of the PV-T collector is 14.5–10.3% larger than for a PV-only system for water inlet temperatures of 20–30 °C, respectively. The developed CFD model reproduces accurately the thermal performance of the PV-T collector, with a maximum error of 6.5% for inlet water temperatures of 20–60 °C. Therefore, this model can be used with confidence to propose alternative designs that achieve a homogeneous temperature distribution in the PV layer and improve the overall PV-T collector performance.

Temperature distribution in multichip IGBT module and its impact on collector current sharing

Multichip Insulated Gate Bipolar Transistor (IGBT) power modules are widely used in high power applications. However, the parallel connection of IGBT chips results in an inhomogeneous temperature/current distribution. In this paper, a thermographic camera is used to capture the temperature distribution of an opened Infineon IGBT module FF600R17ME4 where each IGBT switch has three IGBT chips. The influence of temperature distribution on collector current sharing is then examined in both healthy conditions and bond wire lift-off scenarios. In this research, the critical temperature distribution is demonstrated experimentally at both chip and switch levels. The experimental results reveal that there are, depending on the collector current, 8 °C to 60 °C temperature difference at the chip level and 2 °C to 10 °C maximum temperature variation at the switch level. The severe temperature distribution impacts the collector current sharing less than 1 % variation under healthy conditions and 0.507 % at IC = 240 A upon the first bond wire lift-off. Other findings are that during homogeneous temperature distribution current densities are nearly similar per chip and less dependent on chip temperatures. Findings of this research have the potential to influence multichip Insulated Gate Bipolar Transistor (mIGBT) layout design. For example, having investigated the current density distribution at different operating points, it is recommended to increase the number of bond wires by 11 % for the chip placed in the middle for this particular module in order to increase reliability. Potential future research areas have also been identified.

Automated Design of Honeycomb Conformal Cooling Channels for Improving Injection Molding Quality

Abstract The study of conformal cooling channel usually has adopted two assumptions in model design: the use of (1) a hot runner system and (2) a one-mold-one-cavity design. These assumptions substantially simplify the research. However, most molds are designed using a cold runner system and multiple cavities. These two assumptions may not apply to all commercial systems; hence, a design method for honeycomb CCCs for cold runner systems and multiple cavities is proposed in this study. Specifically, an algorithm was developed to automatically design CCCs for such systems. This algorithm can be used to reduce the cooling time, improve product quality, and ensure that the system temperature is relatively homogenous in practical situations. According to the result of this study, the honeycomb CCC models were more effective at maintaining a homogeneous temperature distribution, reducing shrinkage, and reducing warpage for both parts produced from the same two-cavity mold, thus ensuring consistent part quality.

Thermal Performance Analysis of Functional Parameters of the Floor Heating System in Africa

Buildings frequently utilize radiant heating floors because they offer benefits including effective use of space and homogeneous temperature distribution, which results in increased thermal comfort. The present work aims to investigate the perfect use of floor heating systems analytically and numerically with improved thermal performance to prove their efffficiency in various African climates. The evaluation depends on the functional parameters of the heating system and particularly focuses on floor surface temperature to acquire the desired heat flux and the perfect supply water temperature. According to results, It is desirable to use floor coverings with low thermal resistance and should not exceed R = 0.15 m2 . K/W since it has considerable influence on the thermal efffficiency of the underfloor heating components. The pipe diameter is suggested to be about 20 mm. By comparing pipe spacings of 15 mm and 30 mm, the difference in supply water temperature is approximately 7.4 C. The smaller the pipe spacing, the more energy it delivers and makes the floor much warmer while reducing heating time. Regarding the effect of pipe materials, PE-X is chosen for this study because of its low cost and resistance to corrosion and scaling. As the influence of these studied parameters on floor heating is remarkable, there is also the impact of the ambient temperature of each city on the floor heating efffficiency. The proposed model can be applied and considered potentially beneficial and helpful to the control, and design of floor heating systems, and choosing the right heating source.

Numerical Investigation on the Combustion and Emission Characteristics of Diesel Engine with Flexible Fuel Injection

As the main engineering power plant, diesel engines are irreplaceable in the future. However, the stringent emission regulations impose many tough requirements to their developments. Recently, flexible fuel injection strategy has been recognized as an effective technology in creating an advanced spray and mixture formation and improving combustion efficiency indirectly. However, the detailed combustion and emission behaviors under flexible fuel injection are still unknown. Therefore, this paper aims to investigate the combustion and emission characteristics under flexible fuel injection and explore an optimal injection strategy for high-efficiency combustion. A numerical simulation method is conducted by coupling the large-eddy simulation (LES) model and the SAGE combustion model. Then, the spray mixing, combustion flame propagation and emissions formation under various multiple-injection strategies are investigated. Results reveal that initial an ultrahigh injection pressure has a significant influence on the spray’s axial penetration while dwell time mainly affects the spray’s radial expansion. Under an initial ultrahigh injection pressure, the turbulence kinetic energy (TKE) becomes larger, and the vortex motions are stronger, contributing to a better spray turbulent mixing. Meanwhile, a snatchier flame structure with a favorable level of equivalence ratio and a homogeneous temperature distribution is obtained. In this way, the peak heat release rate (HRR) could increase by 46.7% with a 16.7% reduction in soot formation and a 31.4% reduction in NOx formation.