Combustion Features Research Articles

A novel extraction method for combustion feature of CI engine in electric hybrid power based on engine instantaneous speed

A novel extraction method for combustion feature of CI engine in electric hybrid power based on engine instantaneous speed

STABILITY AND COMBUSTION/EMISSION CHARACTERISTICS OF STRATIFIED DUAL-SWIRL OXY-METHANE FLAMES: EFFECTS OF OXYGEN FRACTION

Abstract The stability, combustion, and emission features of stratified oxy-methane (CH4/O2/CO2) flames stabilized over a dual annular counter-rotating swirl (DACRS) burner, developed for gas turbine combustion applications, were investigated experimentally. The experiments were performed at fixed velocity ratio (Vr=Vp/VS=3.0) in both the primary and secondary streams at a constant primary stream velocity, Vp of 5 m/s and at fixed primary stream equivalence ratio, φP=0.9, and over ranges of oxygen fractions (OFP for the primary stream, OFS for the secondary stream) and secondary stream equivalence ratios. Measurements of flame macrostructure, temperature profiles, and exhaust emissions were recorded to characterize the flames and validate future numerical models. The testing findings revealed no flame flashback within the operational ranges of OFP and OFS and up to φs = 1.0. However, the near stoichiometric operation of the primary stream (φp = 0.9) at OFp =0.38, permitted the main secondary flame to tolerate exceptionally lean conditions (φs = 0.397 at OFs =0.34 and φs = 0.223 at OFs =0.39), raising the thresholds for flame blowout. Increasing OFP from 0.21 to 0.38 significantly reduced φS at blowout from 0.537 to 0.223, corresponding to a decrease in the combustor's global equivalence ratio (φg) at blowout from 0.554 to 0.254 at global oxygen fraction (OFg) from 0.38 to 0.39. Lower OFp values caused earlier flame lift-off, indicating the greater influence of OFp on flame macrostructures.

Effect of H[formula omitted] addition on NH[formula omitted] flame structure and dynamics in a mixing layer

Hydrogen addition has been widely used to improve the combustion performance of low-reactivity fuels such as NH3. In this study, a series of two-dimensional NH3/H2 flames in mixing layers were investigated numerically. The aim is to assess and interpret the effects of H2 addition on the structure and dynamics of ammonia flames. Detailed chemistry and transport models were considered in the simulations. It was shown that for pure hydrogen or ammonia flames, a classical tribrachial structure was observed. The non-premixed branch in the tribrachial flame of NH3 combustion features high heat release rate (HRR), while the two premixed branches are weak. The mixture fraction corresponding to the maximum HRR of NH3 combustion is significantly lower than the stoichiometric mixture fraction. When blending ammonia with hydrogen, a tetrabrachial flame structure consisting of two premixed branches and two non-premixed branches was observed, where one non-premixed branch corresponds to the reaction of NH3, while the other is formed due to the reaction of H2. It was suggested that the formation of the tetrabrachial flame is related to the preferential diffusion of hydrogen. After decreasing artificially the diffusivity of hydrogen to suppress the preferential diffusion effect, the flame exhibits only three branches with the merging of the two non-premixed branches. By analyzing the flame dynamics at the leading edge, it was found that the flame speed (Sd∗) is negatively correlated with the flame stretch (κ) and scalar dissipation rate (χ), with Sd∗ decreasing almost linearly with κ or χ, consistent with previous studies of methane and hydrogen flames. As the H2 concentration is increased, the values of Sd∗ increase due to the enhanced reactivity.

Exploring direct injection strategies for improved combustion efficiency and emissions reduction in dual-fueled RCCI/compressed natural gas engine: A experimental survey

ABSTRACT The dwindling reserves of conventional fuels have spurred research into alternative options for diesel engine, particularly given diesel’s widespread use in global public transportation. Environmental concerns, notably regarding oxide of nitrogen (NOx), and smoke necessitate a shift toward alternative fuels. Diesel’s partial replacement with compressed natural gas in CI engines has shown promise in mitigating smoke and NOx emissions. The Present research utilized an RCCI engine, and employed combinations of Diesel+CNG dual-fuel to analyze how direct injection techniques affect performance, emission, and combustion features. Under full load conditions sans exhaust gas recirculation (EGR) 6 ms and 8 ms CNG yielded superior brake thermal efficiency (BTE) of 30.5% and 29.5% surpassing diesel’s 26%, although excessive CNG induction disrupted combustion, reducing efficiency, and introducing EGR, particularly at 10% enhanced BTE, with 6 ms CNG achieving a peak of 32.5%, slightly lower at 15% EGR with 30.9%. Diesel engine showcased diminishing brake-specific fuel consumption values with CNG supplementation, further mitigated by increased CNG concentrations and EGR rates. Peak combustion pressure decreased in the RCCI engine, with promising results seen at 6 ms CNG, comparable to pure diesel. EGR introduced pressure fluctuations, signifying a dilution effect on combustion, while the net heat release rate displayed increasing trends for CNG, stabilizing with EGR. NOx emissions, peaking in diesel engine, showed reductions with 6 ms CNG, further diminished with EGR implementation.

Secondary air induced flow structures and their interplay with the temperature field in fixed bed combustors

Air staging in solid fuel combustion features widely in small scale domestic boilers to large scale moving grate combustors. Whilst the effects of air staging on the combustion characteristics of these systems are generally known, there is very little insight available into the role of secondary air on the flow and temperature field in the freeboard of batch-type fixed bed biomass combustors. Three-dimensional gas phase simulations using the Transition 𝑘kl-𝜔 and Finite Rate/Eddy Dissipation models were validated against freeboard temperatures and emissions (CO2 and O2) measured on the same set-up. Results show that secondary air at Qs/Qt ≥0.25 induces two recirculation zones, upstream and downstream of its injection point with maximum freeboard temperatures generally observed around these recirculation zones, if Qs/Qt drops to 0.12-0.18 only an upstream recirculation zone is observed until it diminishes by Qs/Qt = 0.06. However, there is a trade-off caused by what appears to be a cooling effect if Qs/Qt is increased between 0.25 and 0.71. Modelling results show that in reacting cases, unlike non-reacting modelling on the same geometry, the strength of the secondary air induced upstream recirculation zone appears significantly stronger.

Collaborative anthracology and cultural understandings of wood charcoal in Marra Country (northern Australia)

This paper presents results from the first collaborative anthracological (archaeological wood charcoal analysis) study in northern Australia’s southwest Gulf of Carpentaria region. The analysis focused on charcoal from a Late Holocene combustion feature and surrounding dispersed charcoal on a buried floor surface. The results suggest that the combustion feature likely functioned as a ground oven associated with a potential specific function, with the majority of fuel wood coming from wakuwaku/marnunggurrun (Callitris columellaris or White Cypress Pine) and Myrtaceae species. These species are found in low woodlands associated with hilly and freshwater springs settings, and their abundance and dispersal are influenced by fire regimes (e.g., Aboriginal fire regimes). Information provided by members of the Marra Aboriginal community about our findings focused on the social and cultural significance of wakuwaku/marnunggurrun, with particular emphasis around its role in past and present wood collection strategies (fire-making and transport, high value timber etc.). By exploring how anthracology and cultural knowledge intersect to generate new understandings about the relational qualities of wood (charcoal), we aim to highlight how collaborative archaeobotany can help reorient research questions in the discipline, providing an opportunity to make such specialised analyses meaningful to communities.

Performance, combustion, and emission features of a diesel engine powered by biodiesel mixture and butanol blends

Performance, combustion, and emission features of a diesel engine powered by biodiesel mixture and butanol blends

Unlocking clean gas with hydrogen: A combustion optimization study

Combining hydrogen with natural gas, a hydrocarbon fuel, is seen as a critical step towards reaching net-zero emissions and creating a cleaner environment. To tackle climate change, major organizations like the U.S. Department of Energy, Energy Innovation, and the International Renewable Energy Agency are promoting the use of hydrogen blended with natural gas. This approach can potentially cut emissions in half compared to relying solely on natural gas. Using the Ansys 2022 R1 CHEMKIN tool, the study analyses combustion features in H2-CNG (compressed natural gas) -air mixtures, considering atmospheric conditions and operational parameters. Blending 50 % hydrogen with CNG results in significant changes, including an increase in laminar flame speed from 48.78 cm/s to 71.52 cm/s. As the hydrogen content in the CNG blend increases from 0 to 50 %, the concentration of free radicals like H, O, and OH rises by 42.86 %, 28.57 %, and 20.00 %, respectively, reaching these values at a 50 % hydrogen blend compared to pure CNG. NSGA-II multi-objective optimization identified that a 50 % hydrogen-blended CNG surpasses pure CNG in laminar flame speed and free radical generation. The research confirms that H2-CNG creates a promising fuel with several advantages. When combusted, H2-CNG mixtures exhibit superior characteristics, including potentially increased efficiency through increased free radical formation and laminar flame speed. This innovation has the potential to significantly reduce carbon footprint and contribute to achieving carbon neutrality goals. The cleaner and more efficient combustion properties of H2-CNG offer a compelling pathway for mitigating climate change.

Furnace MILD combustion versus its open counterpart in hot coflow

The open jet flame in hot co-flow (JHC) has been frequently utilized for fundamental investigations of Moderate or Intense Low-oxygen Dilution (MILD) combustion due to its controllable conditions and relatively easy measurement capabilities. However, practical MILD combustion must take place within a combustor that is enclosed. Therefore, it is necessary to examine the similarity and disparity of combustion characteristics between two flame configurations. This issue is addressed currently. Specifically, we investigate the flow mixing, ignition, and combustion, as well as emission characteristics of non-premixed and premixed JHC and cylindrical furnace (FUR) flames at various values of the environmental temperature (Te) and central jet Reynolds number (Re). For the open non-premixed flames, we employ both previous single-tube JHC (SJHC) combustor and presently modified JHC (MJHC) one that uses the same nozzle configuration as the FUR burner. It is revealed that significant differences occur in flow, combustion and emission characteristics between the SJHC and FUR cases. On the other hand, both non-premixed and premixed MJHC configurations exhibit high similarity to the corresponding FUR cases in terms of upstream flow mixing and combustion features. Moreover, different CO and NOx emissions result from open JHC and close furnace flames due to different post-combustion configuration and residence time. Accordingly, future experiments on non-premixed MJHC and premixed JHC flames are highly recommended for better understanding practical MILD combustion.

Experimental investigation on synergistic slow oxidation and rapid combustion of micron-sized iron and aluminum powders for energy storage application

The investigation into the individual application of iron and aluminum as carbon-free fuel sources has been extensively explored and holds significant promise. However, there remains a gap in understanding synergistic effects achievable through the blending of these two fuels, as well as a need for comparative analyses between the slow oxidation and rapid combustion processes of these fuels to complement each other. This research proposes blending micron aluminum and iron powders to analyze their slow oxidation and rapid combustion features under diverse atmospheric conditions and heating rates, using thermogravimetric methods, kinetic calculations, and in-flow experiments. The research blending micron iron and aluminum powders to analyze their slow oxidation and rapid combustion features under diverse atmospheric conditions and heating rates, using thermogravimetric methods, kinetic calculations, and in-flow experiments. The findings reveal that the combination of aluminum and iron powders promotes oxidation, resulting in increased weight gain and heat flux rate compared to individual metals. Moreover, the triggering temperature rises from 545 to 652 °C with an increase in aluminum powder content. As heating rates increase, characteristic parameters T1, T2, and Hpeak2, rise for both fuels. However, aluminum powder tends to decrease Ti, while iron powder slightly increases it due to differences in oxide layers. The slow oxidation of aluminum and iron powders conforms to different models, yielding distinct oxidation patterns. The apparent activation energy of aluminum decreases from 258.4 to 238.7 kJ·mol−1 with rising heating rates, while that of iron exhibits a lower increase and remains lower than aluminum providing insights into combustion initiation conditions. Combustion initiation is contingent upon the concentration of metal powder and oxygen, with both aluminum and iron powders combustion being enhanced and subsequently attenuated with increasing excess air ratio. However, due to differing reactivity and surface passivation layers, the excess air ratio required for aluminum powder combustion (1.2–2.4) exceeds that of iron powder (1.3–1.7). The research elucidates the mechanisms underlying the slow oxidation of iron and aluminum fuels, delineates suitable combustion conditions, and furnishes new empirical and theoretical underpinnings for the oxidation characteristics of mixed iron-aluminum fuels, thereby advancing metal-fueled energy storage technologies.

Nitramino-polymer with ether bridges and 1,2,3-triazole subunits incorporated into the polymer chain

The creation of novel energetic polymers for future advanced solid composite propellants and gunpowder is an urgent area of modern research. A simple and effective waste-free cycloaddition reaction between dialkyne and diazide comonomers, both bearing nitramine groups, for the synthesis of an energetic polymer containing explosophoric units in the polymer chain has been described. Neither solvent nor catalyst is required for the production of this polymer, the comonomers used are readily available, and the product does not need any purification, and, importantly, this protocol scales well. The resulting polymer, C1Z1, (C14H22N12O8)n, was comprehensively characterized by spectral and physico-chemical methods. Compatibility with energetic plasticizers (NG, DNDEG, DANPE), thermochemical characteristics and combustion features indicate the prospects of target polymer C1Z1 (density, ρ = 1.484 g/cm3; onset temperatures is 230 °C; positive enthalpy of the formation, ΔHf0 = +636 kJ/kg; burning rate at 10 MPa is 9.5 mm/s) as a binder base for energetic materials. Comparison of C1Z1 with nitrocellulose (NC) and their compositions with plasticizers revealed the advantages of C1Z1.

Revisiting palaeolithic combustion features of Theopetra Cave: A diachronic use of dung and peat as fuel

The chemical diagenesis and palaeoenvironmental reconstruction of the Palaeolithic sequence of Theopetra Cave have been studied extensively, but little information is available regarding the details of its combustion structures. The cave is characterized by extensive beds of multi-sequence combustion layers dated between 140 and 50 ka BP, and thick, often stratigraphically complex bodies of ash and charred remains dated between 16 and 13 ka BP. All combustion features contain large amounts of charred and partially charred fibrous organic matter of non-wood plant material and very little charcoal. The structure, fabric, composition, and chemistry of these remains suggest that a mixture of peat and dung was used as a fuel, occasionally enriched with amounts of wood fuel. The integrity of the sequence of combustion structures precludes the possibility that dung was produced by animals inside the cave as their traffic on its wet substrate would have destroyed the burnt layers and homogenized the sediment. The mixture of peat and dung was most likely collected from peatlands associated with swamps of the former so called Karditsa Lake that probably existed in the area until the beginning of the Holocene. Peat and dung were used as a fuel when wood fuel was not available, during the relatively cold intervals of the glacial periods, but also during the last interglacial when the area close to the cave was wooded. Of great interest is that this same fuel was used during both the Middle and the Upper Palaeolithic, presumably by different human species. Although Theopetra appears to be the first site that peat and dung was used as a fuel during the Middle Palaeolithic, it is suggested that other sites may have used this fuel as well. This has important consequences in understanding the evolution of human pyrotechnology particularly during glacial periods.

The Early Upper paleolithic deposit of Mughr el-Hamamah (Jordan): Archaeobotanical taphonomy and site formation processes

With a rich, well-dated Early Upper Palaeolithic layer, the Mughr el-Hamamah cave site is key for understanding the Middle-Upper Palaeolithic transition in the Levant. The archaeological deposit consists of two units. Layer A resulted from pastoral activities during the 20th century and Layer B dated between 44.5 and 40.0 ky BP. During Layer A’s formation, shepherds disturbed Layer B, redepositing Early Upper Palaeolithic sediments and lithic artefacts in Layer A matrix. Activity from Layer A’s formation also resulted in spatially patchy percolation and bioturbation, leaving microarchaeological traces such as dung spherulites in some areas in Layer B. In contrast, contemporaneous chemical diagenetic processes from Layer B’s primary formation caused spatially uneven post-depositional dissolution of animal bone. In this article we present a multi-proxy microarchaeological approach to investigate the post-depositional processes in Layer B, focussing on possible impacts on the plant archaeological record. The identification of intrusive spherulites from shepherds’ activities define the limits of disturbance in Layer B. Micromorphological analyses have identified four intact micro-facies in Layer B, representing an interplay of natural and anthropogenic factors. Micromorphological details in bedded combustion features favour the interpretation that associated phytoliths represent fuel traces. Dicot fruit phytoliths occur in the western area of the cave, where well-preserved charred wood and seeds were also found. Grass-diagnostic phytoliths correspond to C3 and C4 taxa, indicating an overall humid environment with dry spells. Microarchaeological analysis identifies traces of both bedded and dispersed hearth materials, mixed with variable plant resources for food, fuel, and possibly other uses. This strengthens the interpretation of Mughr el-Hamamah Layer B as a dense, complicated palimpsest of recurring activities, formed over many millennia.

Combustion features of dispersed aluminum and boron in high-energy composition

Combustion of dispersed metals in an oxidizing environment is of practical interest, which is related to the prediction of characteristics of high-energy compositions (HECs) containing metal powders, as well as the characteristics of various propulsion systems and gas generators. The research studies peculiarities of ignition and combustion of dispersed systems of Al, B and Al-B mixture in gas products formed during thermal decomposition and combustion of HEC components. In the study of the characteristics of ignition and combustion, the development of flame processes, a continuous CO2 laser (high-speed radiant heating) and a continuous-pressure flow bomb (stationary combustion), including the filter system for the capture of condensed combustion products (CCPs) were applied. It was found that the high reactivity of dispersed Al reduces the ignition time and increases the burning rate of HECs, and increases the volume fraction of fine condensed particles. The use of amorphous B or Al-B mixture (17.2/82.8 mass ratio) increases the ignition time (up to 62%) and significantly reduces the burning rate of HECs, at the same time, the volume share of large CCPs increases due to the melting of the oxide layer on the surface of B particles and their increased cohesion. Analysis of CCPs showed that fine and large agglomerate particles were formed on the surface of the reactive HEC layer, which contain oxides of the metals used. When Al particles are burned together with B particles, complex oxides (aluminum borates) can be formed.

Early detection of thermoacoustic instability in an O2/CH4 single-injector rocket combustor using analysis of chaos and deep learning models

Thermoacoustic instability (TAI) presents a critical challenge for lean-burning combustors and rocket engines. The early detection of instability is crucial, and to address this, a data-driven prediction framework has been established for TAI in a sub-scale rocket combustor with variable chamber length. Nonlinear combustion features are generated from time series of dynamic pressure using recurrence matrices. Deep learning models are then utilized to train these features and predict the proximity of impending TAI. The performance of the proposed method is investigated through cross-validations of 12 groups of hot-fire test datasets. Remarkably, the prediction performances are in good agreement with measured experimental data, with most instabilities being predicted dozens of milliseconds in advance. This capability paves the way for the early implementation of active control systems in full-scale combustors in the future. The prediction performances are also compared with state-of-the-art TAI prediction methods.

Magnetic micro-archaeology: a method for conducting rock magnetic microfacies analysis on archaeological soil micromorphology samples, with a case study from El Salt, Alcoy, Spain

For geoarchaeologists the use of multiproxy and multimethod integrative approaches has become common for studying the sedimentary context of archaeological materials. In this paper, we introduce a novel approach that combines rock magnetic analysis with micromorphological analysis. We first conduct a brief examination of the magnetic properties of organic resins used in micromorphology to understand the potential impact of the resin and manufacturing process on the magnetic signature. It is crucial to understand the original production of the samples to ensure that endothermic reactions do not compromise the magnetic data. We illustrate the advantages of this approach through a case study of a pit hearth from the Neanderthal archaeological site of El Salt in Alcoi, Spain. This study utilises archived micromorphological samples of a pit hearth (combustion structure H77) initially described by Leierer et al. (J Archaeol Sci 123:105237, 2020). Rock magnetic analysis of multiple magnetic parameters—including magnetic susceptibility, natural remanent magnetization, and progressive isothermal remanent magnetization—reveals that each microfacies type exhibits a unique magnetic pattern, even if there is overlapping in signatures across some magnetic parameters. The interpretation of the magnetic data aligns with the results and microfacies descriptions previously provided by Leierer et al. (J Archaeol Sci 123:105237, 2020), further supporting the interpretation of the combustion feature as being in situ with a history of repeated use. The approach presented here offers an enhanced tool for micromorphologists to better understand the magnetic characteristics of microfacies units in higher resolution and establish direct connections to the micromorphological results.

The Effect of CuO on the Thermal Behavior and Combustion Features of Pyrotechnic Compositions with AN/MgAl

Ammonium nitrate (AN) is of considerable interest to researchers in developing new types of energetic mixtures due to the release of environmentally benign gaseous products during burning and thermal decomposition. However, poor ignition and a low burning rate require special additives to speed up this process. The advantage of this research is the use of high-energy aluminum-based alloys as fuel to compensate for the disadvantages of AN. In addition, the effect of copper oxide (CuO) on the burning kinetics and thermodynamics of the energetic mixture based on ammonium nitrate–magnesium–aluminum alloys (AN/MgAl) is investigated. Alloys based on aluminum were created through a process of high-temperature diffusion welding, conducted in an environment of argon gas. The structure and thermal characteristics of alloys are determined by X-ray diffraction, scanning electron microscopy, and DTA-TG analyses. It has been found that CuO has significant effects on the thermal decomposition of an AN/MgAl-based energetic mixture by shifting the decomposition temperature from 269.33 °C to 261.34 °C and decreasing the activation energy from 91.41 kJ mol−1 to 89.26 kJ mol−1. Adding CuO reduced the pressure deflagration limit from 2 MPa to 1 MPa, and the linear burning rate of the AN/MgAl energetic mixture increased approximately twice (rb = 6.17 mm/s vs. rb = 15.44 mm/s, at a chamber pressure of P0 = 5 MPa).

Study on arc characteristics and combustion feature of tree-wire discharge fault in distribution line

In recent years, there have been cases of wildfires caused by electrical faults around the world. The arc plasma formed by tree-wire discharge can easily lead to wire damage or fuse, carbonization or combustion of branches.In this paper, a magnetohydrodynamic model of tree wire discharge arc is established by multi-physical field simulation, and the changes of arc shape characteristics and tree wire temperature under the influence of wind speed and wire type are studied. Then, the experimental platform is built to verify the simulation and measure the fault current waveform. Finally, the characteristics of the fault waveform in time domain and frequency domain are analyzed. The simulation shows that under the influence of wind, the arc root will shift, the arc temperature will decrease, and the two electrodes of the tree wire will be ablated. Through experiments, during the development process of tree-wire fault, the change of branch resistance is divided into five stages, and the leakage current is related to it. After being affected by wind, the pulse peak and zero current time of the fault waveform increase significantly and are positively correlated with the wind speed.The harmonic content is analyzed through frequency domain analysis, and monitoring the harmonic content during the fault process, combined with current characteristics, can effectively distinguish it from other HIFs, providing a reference for the study of arc characteristics and early warning of wildfires caused by tree-wire discharge in distribution lines.

Engine behavior analysis on a conventional diesel engine combustion mode powered by low viscous cedarwood oil/waste cooking oil biodiesel/diesel fuel mixture – An experimental study

Binary biofuel is the best alternative source that completely replaces petroleum-based fuel. In this study, we have experimented with the waste cooking oil and cedarwood oil as biofuel in a DI CI engine for various proportions and related its combustion, emission, and performance characteristics to those of base diesel. This study aims to eliminate the utilization of fossil fuel in a diesel engine by introducing green binary fuel (low viscous fuel resulting from the blending of cedarwood oil with WCO biodiesel) successfully. The objective of the study is to convert cedarwood – WCO into green binary fuel and investigate its performance, emission, and combustion properties. The transesterification process is utilized for the enhancement of WCO as biodiesel. It occasioned a reduction in brake thermal efficiency as the addition of waste cooking oil in the blend increased. At the same time, the maximum value of BTE of 27.8% was attained for B10C90 (10% transesterified waste cooking oil and 90% cedarwood oil in volume), whereas it was 28.1% for diesel at maximum load conditions. The BSEC was 15.4 MJ/kW-hr for B10C90 and 12.8 MJ/kWhr for diesel. The emission characteristics, CO, HC, NOx, CO2, and smoke for B10C90 were 17.93 g/kWhr, 0.55 g/kWhr., 20.09 g/kWhr, 2210.9 g/kWhr, and 25.55%. Combustion features such as NHRR, burn duration, MPRR, combustion efficiency, Ignition delay, and coefficient of variance for B10C90 were 53.74 bar, 29.38 CAD, 4.71 bar/CAD, 99.7%, 7.01 CAD, and 4.73% respectively. It showed that B10C90 had comparable performance (BTE) and combustion values to mineral diesel with better emission characteristics.

Exploration and comparison of the relationship between PAHs and ROS in PM2.5 emitted from multiple anthropogenic sources in the Guanzhong Plain, China

Anthropogenic emissions have emerged as an important source of urban atmospheric PM2.5, exacerbating air pollution and the associated health implications. This study analyses PM2.5, originating from major anthropogenic sources (industries, motor vehicles, and solid-fuel combustion for domestic applications) in the Guanzhong Plain in China, along with the parent- (p-), alkylated- (a-), and oxygenated- (o-) polycyclic aromatic hydrocarbons (PAHs) and reactive oxygen species (ROS) levels in PM2.5. Industrial emissions are mainly characterised by high abundances of benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), and benz[a]fluoranthene (BaF). The 4-ring p-PAHs, such as fluoranthene (FLA), pyrene (PYR), benzo[a]anthracene (BaA), and chrysene (CHR) proportions and the diagnostic ratios of indeno[1,2,3-cd]pyrene (IcdP)/[IcdP + benzo[ghi]perylene (BghiP)] and 1-acenaphthenone (1ACO)/[1ACO + 9-fluorenone (9FO)] in motor vehicle emission PM2.5 were higher than the other sources. Household solid fuel combustion features high proportions of methylnaphthalene (M-NAP), i.e., 2 M-NAP and 1 M-NAP and 3-ring p-PAHs. Acenaphthylene (ACY), acenaphthene (ACE), anthracene (ANT), 1,4-chrysenequinone (1,4CHRQ), and reactive oxygen species (ROS) were positively correlated among the three anthropogenic sources. Moreover, the correlations between other PAHs and ROS varied significantly among the three sources. As mixed and compound organic pollutants, 2- and 3-ring p-PAHs were more positively correlated with the ROS activity of household solid fuel combustion sources compared with industrial and motor vehicle sources. Based on the relative contribution of these three sources to PAHs in PM2.5, we estimated the cancer risks of males and females in the Guanzhong area to be 2.95 × 10−6 and 2.87 × 10−6, respectively, exceeding the safety threshold of 1 × 10−6. This study provides a basic dataset for conducting a refined source apportionment of PM2.5 and a scientific basis for further understanding the relationship between PM2.5, PAHs, and ROS in northern China.