Water Content Ratio Research Articles

Studying the Geotechnical Properties of Clayey Soil Contaminated by Kerosene

This study focuses on investigating the impacts of kerosene on the physical, mechanical, and chemical characteristics of clay soil. The soils specimens are contaminated artificially with six ratios of kerosene (5, 10, 20, 30, 40, and 50) % calculated according to the dry weight of soil. The artificial contamination includes air drying of the disturbed soil, then placed in plastic containers and mixed with the field water content and the specified concentration of kerosene to ensure getting homogenous contaminated soil specimens. The contaminated soil specimens left for 30 days in plastic containers covered by nylon sheets to control the water content and prevent volatility of contaminant. The results of tests proved that different ratios of kerosene have different impacts on the engineering and chemical characteristics of soil specimens. The specific gravity, percentages of fine particles, optimum water content, the initial and final void ratio, coefficient of consolidation, swelling index, permeability, the undrained shear strength, effective shear strength parameters, and the rate of reduction of initial pore water pressure are reduced significantly with increasing the content of kerosene in soil. Generally, the concentration of kerosene less than 10% has slight impacts on the studied characteristics of soil specimens.

Compressibility behaviour and properties of peaty soils from Dian-Chi Lake area, China

Peat deposits are widely encountered in many parts of the world and present various challenges for the geotechnical engineering community because of their low bearing capacity and very high compressibility and creep potential. This paper describes extensive index and oedometer testing to investigate the compressibility behaviour/properties of deep, strongly to completely humified peat and highly organic fine-grained soil layers at the northeast shore of Dian-Chi Lake in Kunming, southwest China; a region that recently is experiencing significant infrastructure construction. Compared to surficial peat deposits, the peaty soil layers investigated, with organic contents ranging 23.5–80.0%, have been subjected to a 6.7-m depth of inorganic soil overburden, such that they have substantially lower water content and void ratio and higher preconsolidation stress. Nevertheless, with deduced Cα/Cc = 0.04–0.07, Cr/Cc = 0.14–0.18 and Ck/e0 = 0.23, the Dian-Chi peaty soils exhibit similarities with surficial fibrous peats from other countries/regions. Unlike fibrous peats, however, the Dian-Chi peaty soils have extremely low permeability, with deduced kv values of the order of 1 × 10−9 to 1 × 10−10 m/s, consistent with their hunification level. Existing linear Cc – w0 correlations were found inadequate for the Dian-Chi peaty soils, such that a new Cc – w0 correlation is proposed from curve-fitting of the gathered experimental data to better capture their non-linear relationship.

Soil infiltration and conservative solute transport characteristics with different viscosity of hydroxypropyl methyl cellulose

AbstractHydroxypropyl methyl cellulose (HPMC), a potential soil improver with the ability to hold water, has practical applicability in alleviating soil and water nutrient loss. By using Cl− as tracer ions, we evaluated the effects of different HPMC viscosities on soil water infiltration characteristics and conservative solute migration characteristics. Hydroxypropyl methyl cellulose with viscosities of 2 × 104, 6 × 104, 10 × 104, and 20 × 104 mPa s−1 was selected. Experimental results revealed that the cumulative infiltration amount, wetting front migration distance, and infiltration rate decreased significantly with increased HPMC viscosity. The addition of HPMC delayed the soil solute transport process, and HPMC with a higher viscosity caused greater soil solute transport delay. Both the convection‐dispersion equation (CDE) and the two‐region model (TRM) accurately simulated solute transport, but the simulation accuracy of the TRM was higher. Results of parametric fitting based on the TRM indicated that the average pore water velocity, hydrodynamic dispersion coefficient, and dispersion degree decrease with increased HPMC viscosity. The average pore water velocity decreased by 13.6–28.2% relative to the control group (CG). Compared with the CG, the water content ratio in movable water of HPMC groups changed irregularly with an increase in viscosity. The mass exchange coefficient increased significantly compared with the CG, with an irregular trend. These data will be useful in the application and promotion of HPMC as a soil improver.

INVESTIGATION OF EFFECTS OF RECYCLED AGGREGATES AND BLAST FURNACE SLAG ON PROPERTIES OF SELF-COMPACTING CONCRETE

The effects of simultaneous use of recycled aggregates and ground blast furnace slag as a percentage of cement-constituting materials on different properties of fresh self-compacting concrete (SCC) are investigated in this study. To this end, three series of SCC mixtures with a fixed volume of cement paste equalling 380 ltr/m3 (2.36 gal/ft3) and the replacement ratio of coarse aggregates (fifty percent and one hundred percent) and total aggregates (zero percent, fifty percent and one hundred percent) were prepared. The water content ratios in the first, second and third series were 0.4, 0.45, and 0.5, respectively. The results of the compressive strength tests for 7-day, 14-day and 28-day cubic specimens and compressive strength and Brazilian test results for 28-day cylindrical specimens were used as control parameters governing the SCC resistive quality. The results of fresh SCC tests (including slump-flow and T50 tests, V-funnel test, and L-box test) showed that the negative effect of recycled fine aggregates on fresh SCC properties is significantly more than that of recycled coarse aggregate. However, recycled SCC with acceptable properties can be obtained with a slight increase in the amount of superplasticisers used in the presence of slag.

Relationships between undrained shear strength, liquidity index, and water content ratio of clays

Clays are very important in environmental geotechnical applications because of their characteristics. This paper considered over 500 data from literature and from laboratory. Undrained shear strength (remolded and undisturbed), liquidity index (IL), and water content ratio (WCR) have been compared among each other. Because natural clays have different physical and mineralogical properties, no unique relationship exists. The relationship between remolded and undisturbed undrained shear strength and liquidity index (IL) is scattered. On the contrary, if only remolded undrained shear strength values are plotted against the liquidity index, a good tendency is observed considering also the ratio of plastic limit to liquid limit in the range of IL between 0.8 and 1.3.

Estimation of water retention behaviour of bentonite based on mineralogy and mercury intrusion porosimetry tests

In this paper a water retention model is developed based on soil mineralogy and microscopic features of material behaviour. The model estimates the water content at a given total suction as the sum of the bentonite minerals’ interlayer water and water in the interparticle pores. The paper proposes simple formulae to estimate the interlayer water content and interlayer void ratio based on mineralogical properties. Additionally, the model uses mercury intrusion porosimetry (MIP) measurements to approximate the water content in the larger pores. The validation of the proposed procedure relies on published data for MX-80 and GMZ bentonites and yields promising results. Even though the discussion and the validation are restricted to bentonite here, the procedure is generic in nature and can be modified easily for other geomaterials. The paper also offers insights into the links between a soil's microstructure and its macroscopic behaviour. The contribution provides a new tool for quick indirect estimation of the water retention behaviour of porous materials with known mineral composition and available microstructural data – for example, based on the MIP tests. Such a tool is of great practical interest in design – for example, nuclear waste repositories, where a large material pool may be considered initially.

Determination of the Transportation Limits of Heavy Crude Oil Using Three Combined Methods of Heating, Water Blending, and Dilution.

Conventional methods for pipeline transportation of heavy or extraheavy crude oils adopt heating, water blending, and dilution, and several methods are generally required to be used simultaneously to ensure normal transportation. However, how to determine the optimal transport boundary conditions for heavy oils is still one of the technical challenges. In this paper, the circulating piping experiment at different water contents (0–90 wt % with an interval of 10 wt %) and temperatures (65–90 °C with an interval of 5 °C) of three heavy oils from the Xinjiang oilfield is carried out. The apparent viscosity calculated from the experimental data of the circulating pipeline shows that when the water content is below the phase inversion point, the apparent viscosity increases and when the water content is close to the phase inversion point, the apparent viscosity increases nearly three times. Only when the water content is greater than the phase inversion point, the apparent viscosity shows a downward trend. Also, then, various viscosity prediction models with different independent variables, which mainly included temperature, water content, and dilution ratio, are selected and verified. Based on experimental data of six crude oils, a prediction model of the phase inversion point is established. Simultaneously, a method for determining the boundary conditions of heavy oils using the combined methods of heating, water blending, and dilution is proposed, while a set of simple decision diagrams of boundary conditions for heavy oil is also described. Finally, verified by the heavy oil pipeline of the Bohai LvDa oilfield, the gathering and transportation limits determined by this method are consistent with the operating parameters of the oilfield.

Effects of reactants/coolant non-uniform inflow on the cold start performance of PEMFC stack

The failure at equally distributing reactants among different channels within the stack leads to uneven reaction and gas concentration distribution in the catalyst layers, which consequently impacts the performance and durability of proton exchange membrane fuel cell stacks (PEMFCs). A three-dimensional, transient, non-isothermal cold start model for PEMFCs with parallel flow-field configuration and coolant circulation is developed in this work to investigate the effects of non-uniform distribution of reactants/coolant inflow rates on the cold start process. The results show that the effect of non-uniform inflow on ice formation amount is obvious and that on the distribution uniformity of current density is apparent over the cold start survival time. Additionally, the simulation predictions show that the non-uniform initial membrane water content distribution due to the purge procedure can significantly increase the rate of ice growth and deteriorate the uniformity of current density distribution in the membrane. It is found that high stoichiometry operating condition is favorable to cold startup, but may result in drying in the membrane at regions close to the channel inlet side. As non-uniform inflow rates issue is inevitable in actual PEMFC stack operation conditions, our results demonstrate that the initial membrane water content and cathode stoichiometry ratio need to be identified to moderate the effects of reactants/coolant inflow maldistribution and to maintain a stable cold start performance for the PEMFC stack.

Subsoil shear strength – Measurements and prediction models based on readily available soil properties

Traffic-induced long-term damage to agricultural subsoils is a serious threat in modern, mechanized agriculture. Soil failure due to shear stresses is often not considered in soil compaction models but probably contributes significantly to soil structure deterioration. We measured shear strength for a total of 720 undisturbed soil cores collected at nine different locations in Denmark. Soil clay content ranged from 0.025 to 0.375 kg kg−1. We sampled at soil depths 0.3, 0.5 and 0.8 m and drained the soil cores to either -50, -100 or −300 hPa matric potential prior to shear tests. We used a shear annulus device to apply shear stress to the soil cores. The normal load, NL, in tests was either 30, 60, 90, 120, 150 or 180 kPa. Soil shear strength, τ, was estimated as the peak (maximum) shear stress at soil failure. Soil cohesion and angle of internal friction was estimated from linear regression of τ and NL. Multiple regression indicated that soil cohesion was well predicted by soil organic matter, clay content, the initial (preload) suction stress, σw, and soil bulk density. σw was calculated from water saturation and the matric potential. It was superior to quantity expressions of soil water (volumetric water content and water ratio) in explaining the trends in soil cohesion. Quantity of soil water should not be used in prediction models across soil types. The angle of internal friction correlated poorly to soil properties. Soil shear strength at a given NL could be well described by a model combining the above soil properties with the NL. This pedotransfer function predicted reasonably well the measured shear strength from two independent data sets. More studies are needed to evaluate a range of methodological aspects and for inclusion of more clay-holding soils. We encourage the inclusion of soil shear failure prediction in soil compaction models and suggest a specific procedure for this.

Effect of hydraulic gradient on the permeability characteristics of foam-conditioned sand for mechanized tunnelling

Low permeable soil is important for stabilising the tunnel face during mechanized tunnelling in sandy soils under water level. Foam is one of the most common conditioning agents to achieve low permeability of the excavated soil. This study investigates the effect of hydraulic gradient on the permeability characteristics of foam-conditioned sand in various conditioning states, according to a series of experimental permeability tests under different hydraulic gradients. With an increase in the hydraulic gradient, the duration of the initial stable stage of the permeability coefficient either gradually decreases or completely disappears. In the rapid growth period, the permeability coefficient increases greatly. The pipe flow model is introduced to analyse time-dependent permeability characteristics of conditioned sand under different hydraulic gradients. The results shows that as hydraulic gradient increases, the time required for water to penetrate throughout the foam plugs decreases and the enlargement rate of the assumed pipe diameter increases in the rapid growth period. Finally, changes in the conditioning parameters for EPB shield tunnelling and EPB pipe-jacking under the influence of hydraulic gradient are discussed. With an increase in the hydraulic gradient, the range of conditioning parameters of the soil that satisfies the shield tunnelling permeability requirement gradually narrows and moves towards a low water content (w) and high foam injection ratio (FIR). The results show that an increase in the hydraulic gradient poses a more serious challenge for foam-dominant soil conditioning during mechanized tunnelling.

Effects of surface straw mulching and buried straw layer on soil water content and salinity dynamics in saline soils

Field experiments were conducted to evaluate the effects of wheat straw return methods, which included the use of surface straw mulch and a buried straw layer, on soil water content, electrical conductivity (EC), and sodium adsorption ratio (SAR) of saline sodic soils in an effort to identify useful ways for reducing soil salt accumulation and enhancing soil water content. The results showed that the straw return treatments were effective for inhibiting salt accumulation and soil water loss, resulting in a reduction of EC and SAR but an enhancement of soil water content. After a year-long experiment, compared with the treatment with no straw return, the straw burial and straw mulching treatments decreased the EC by 10.5% and 3.5%, reduced the SAR by 7.4% and 21.5%, and increased the soil water by 0.9% and 4.4%, respectively. Furthermore, the combined application of straw layer burial and surface straw return had a more significant effect than the individual treatments; the positive effect of straw return occurred mainly focused in the topsoil (0–40 cm) and decreased with increasing soil depth. Our results allowed us to conclude that burial of the straw layer was necessary to enhance the effects of surface mulch, and the combination of surface mulch (3.0 t ha−1 of wheat straw) and straw layer burial (6.0 t ha−1 of wheat straw) proved to be a better straw return method than the others.

Hydraulic conductivity characteristics of carbonated reactive magnesia-treated silt

Carbonation of reactive magnesia (MgO) has recently received increasing attention in the area of soil stabilization and ground improvement. However, as a critical parameter in terms of long-term seepage behavior in the geotechnical analysis, the hydraulic conductivity of carbonated reactive MgO-stabilized silt has not been fully studied. In this context, the effect of water-MgO ratio (ratio of initial water content to MgO content, w0/c) and carbonation time on hydraulic conductivity (or permeability) characteristics was systematically investigated. Serial microstructural tests including mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses were applied to elucidate the intrinsic mechanisms. The obtained results indicate that as the initial water-MgO ratio decreases, the void ratio gradually decreases and the reduction of hydraulic conductivity becomes less prominent because of the little presence of flow paths. The hydraulic conductivity of carbonated MgO-admixed silt similar to that of PC-treated silt is mainly governed by the porosity, and its correlation with void ratio is proposed in the article. The variations of permeability with void ratio are consistent with those of the cumulative pore volume from MIP results in general, and the medium pores (3–30 μm) are substantiated to be the primary contributor in controlling the permeability. SEM and DSC analyses reveal that the cementation of soil particles and filling of hydrated magnesium carbonates marginally reduce the voids and permeability. The reasons for changes of permeability behaviors have been confirmed by the pore-size distribution and microstructure characteristics.

Numerical simulation of co-incineration of sewage sludge and municipal solid waste in municipal solid waste incinerator

Incineration is widely used as an important method of sludge and garbage utilization and harmless treatment. The simulations of co-incineration of sludge and municipal solid waste are conducted by computational fluid dynamics method(CFD) in a MSW incinerator. The study focuses on the effect of mixing proportion, moisture content of sludge, excess air coefficient and primary and secondary air distribution ratio on the combustion progress. Simulation results indicate that the combustion temperature of furnace decreases rapidly with the increase of the mixing proportion and moisture content of sludge, which is mainly because the moisture content of sludge is higher than that of MSW as well as its low calorific value. As a result, it is recommended that the water content and mixing ratio of sludge would be controlled below 40% and 7% respectively. Therefore, the fresh sludge should be dried before entering the furnace.

Construction of a large-section long pedestrian underpass using pipe jacking in water-filled clay

This paper presents a design and construction schemes of a pipe jacking project in Kunming, China in detail. The underpass, having a width of 6.9 m and a height of 4.9 m, was jacked 46m in water-filled clay under a busy viaduct with 4.5 m overburden soil., Some adjustments have been made to the construction process due to the characteristics of the soil layer, the surrounding environment and the existing pipeline. During the whole construction process: the pipe jacking passes through the shallow confined aquifer with high water content and high void ratio, it is easy to produce rheology. In addition, the attitude control of whole tube is also a difficulty, and some adjustments have been made to this problem; the monitoring scheme has also been adjusted accordingly. In general, this project is completed successfully and the traffic on ground and viaduct runs well during the whole construction process.

STRESS ANALYSIS OF EMBANKMENT DUE TO DIFFERENT IN CONSTRUCTION CONDITIONS

: In recent years, many examples of soil structure collapse due to heavy rainfall have occurred. Because of this, it is urgent to establish a method to evaluate and examine long-term embankment structure quality. Japan's conventional design method insufficiently evaluates embankments. Although this method is shifting to a performance-based design to cope with recent abnormal weather, an effective design method has not yet been established. Therefore, this research performs an initial stress analysis of embankment, accounting for differences in construction conditions. Notable in this study, is the comparative analysis of results, considering the initial water content ratio, one layer of discharge thickness, rolling compaction, and other given structural conditions that differed from conventional design standards. To do this, first the initial moisture content ratio was determined by reproducing the compaction by analysis. Second, based on the dynamics of unsaturated soil, the rainfall intensity was analyzed in order to confirm the variation of the initial stress due to rainfall. Lastly, and most critically, the dynamic change in embankment performance was analytically expressed, and the optimal structural conditions of embankment, grouped by rainfall history, was examined

Experimental and analytical investigation of the response of a mud layer to solitary waves

Although the different aspects of wave-mud interaction have been studied by many researchers, few studies have been conducted on the effect of solitary wave on the particle velocities formed in the layers of cohesive sediments. The main objective of the present study is to investigate different features of the mud mechanical responses to the solitary wave loadings. This paper describes a comprehensive study of solitary wave-mud interaction by means of sets of laboratory tests, in which time series of the velocity in the water and mud layers, as well as free-surface evolutions, were measured. Wave damping and several aspects of the mechanical response of the mud layer to solitary wave loadings, e.g. mud particle velocities, the ratio between positive and negative peak velocities, time shift between peak velocities in the mud and water layer and the mud movement period, were studied through nondimensional parameters. It was shown that, at higher values of the mud water content ratio, the time shifts between the peak velocities in the mud and water layers decrease, whereas the mud movement period and the ratio of the positive to the negative peaks increase. Similar trends were observed as the height of the solitary wave was increased. A viscous analytical two-layered model has been developed. Comparing to the measurements, the present model and the model of Liu and Chan (J Fluid Mech 579:467–480, 2007) presented a similar behaviour for simulating the mechanical response of mud under the action of a solitary wave and both models performed better than the model of Jiang and Zhao (J Waterw Port Coast Ocean Eng 115:345–362, 1989).

Polyacrylonitrile-supported self-aggregation crosslinked poly (vinyl alcohol) pervaporation membranes for ethanol dehydration

Highly water-selective poly(vinyl alcohol) (PVA)/polyacrylonitrile (PAN) pervaporation membranes were prepared by combining self-aggregation crosslinking reactions for PVA through ammonium persulfate (APS) initiations and interface physicochemical structure regulations for PAN supports. The membrane physicochemical properties were tested and the pervaporation performances were investigated by separation of 95 wt% ethanol aqueous. The results showed that the swelling degree and crystalline region of PVA membranes decreased with the increasing of APS content. On the contrary, the gel fraction of PVA membranes increased. Interestingly, the interface physicochemical structure between the PAN support and PVA separation layer played an important role in pervaporation processes. When the PAN supports were treated by sodium hydroxide (NaOH) and tannic acid (Ta), the water fraction in permeation always kept over 99.99 wt%, especially after Ta treatment. After optimization, the membrane based on PVA content of 8 g, 1.25 g self-crosslinking agent of APS and spin-coated onto H2-PAN (PAN modified by NaOH and Ta respectively), showed good permeability-selectivity and long-term performance stabilities. The total flux and water content ratio in permeation were 117.6 g/(m2h) and 99.99 wt% respectively by using the PVA8-1.25/H2-PAN membrane. After running for 120 h, the membranes still displayed a good stability for the ethanol dehydration in the pervaporation process. Importantly, the ethanol solution could be concentrated to over 99.99% using this polyacrylonitrile-based self-aggregation crosslinked poly (vinyl alcohol) pervaporation dehydration membrane.

The relationships between water storage and biomass components in two conifer species.

BackgroundWater storage is a significant physiological index of vegetation growth. However, information on water storage at the individual tree level and its relationship to climatic conditions and productivity is scarce.MethodsWe performed a comparative analysis of water storage using field measurements acquired three age classes of Chinese fir (Cunninghamia lanceolata) and Korean larch (Larix olgensis). The distributions of water storage, water content ratio and dry mass were presented, and regression analyses were used to confirm the relationships of water storage and water content ratio to dry mass components, respectively.ResultsOur results indicated that water was mostly concentrated in the stem xylem, which aligned well with the distribution of dry mass in both conifer species. However, the water storage of the stem xylem was always higher in Chinese fir than in Korean larch. The average water content ratio of both conifer species decreased with age, but that of Chinese fir was always higher than that of Korean larch. There was a significant difference in the water storage proportion in the components of Chinese fir (P < 0.001) and Korean larch (P < 0.001). The effects of age class on the water storage of Chinese fir (P = 0.72) and Korean larch (P = 0.077) were not significant. Interestingly, significant positive linear correlations were found between fine root water and leaf water and mass in Chinese fir (P < 0.001, R2 ≥ 0.57) and Korean larch (P < 0.001, R2 ≥ 0.74). The slopes showing that the linear relationship between tree size and water content ratio of stem xylem were always steeper than that of other components for the two conifers.ConclusionOur study indicates the similar water related characteristics and their close relations to biomass accumulation and growth in both fast growing species at contrasting climates, illustrating the same coherent strategies of fast growing conifers in water utilization.

CO2 carbonation-induced improvement in strength and microstructure of reactive MgO-CaO-fly ash-solidified soils

An innovative approach combining CO2 accelerated carbonation with industrial by-products is systematically investigated to produce low-carbon and sustainable cementing materials, in which reactive MgO-CaO-FA (fly ash) blends are introduced to replace traditional Portland Cement (PC) with high energy consumption, mineral resources demand and CO2 emissions. The effect of initial water content, carbonation time, binder amount and mass ratio of MgO/CaO on the mechanical and microstructural properties of carbonated solidified soils is analyzed through unconfined compressive strength (UCS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. The carbonation efficiency and carbon footprint of cementitious materials are evaluated under different schemes. The test results indicate that CO2 carbonation combined with reactive MgO-CaO-FA blends is proved highly effective and reliable to improve the strength performance of soil samples. The compressive strength of carbonated soils increases with binder content and mass ratio of MgO/CaO, which is related to the densification of pore system by carbonation products. An optimum UCS is reached at 6 h of carbonation, followed by a plateau or an important decrease with carbonation time. Water content controls the diffusion and permeability rate of CO2, affecting the chemical contact between Ca2+/Mg2+ released from MgO-CaO-FA blend and dissolved CO2 and further the strength of carbonated samples. XRD and SEM results demonstrate that the strength gain is mainly attributed to the formation of carbonation products (CaCO3, MgCO3), facilitating the densification and cementation of solidified materials. High-Ca FA promotes the carbonation efficiency by reducing porosity and providing nucleation sites for carbonate precipitation, while reactive MgO plays a more important role than CaO in developing binding capacity and building skeleton structure. The carbon footprint analysis reveals that compared with PC, the net CO2 emissions of MgO-CaO-FA blends are effectively reduced by 38.8–64.7%. The coupling technique of CO2 carbonation with industrial by-products is proved a feasible alternative to traditional PC in soil solidification.

Experimental investigation of nitrogen oxide emissions from emulsified fuel combustion incorporating a rapid internal mixing injector by using temperature–time scaling

The aim of the present study was to clarify the effect of the operating parameters of the global equivalence, atomizing air, and water content ratios on nitrogen oxide (NOx) emissions from the combustion of emulsified fuel in furnaces incorporating a rapid internal mixing (RIM) injector. NOx concentration was measured at the exit of the furnace, and the temperature distributions were measured using thermocouples. The flame lengths under various conditions were evaluated by analyzing photographic images. On the basis of information on the temperature and flame length, the dominant factors determining the amount of NOx emission were investigated using the temperature–time scaling of NOx. As a result, the dominant factors were found to be the gas temperature in the flame holder and the flame length. The NOx emission index was observed to increase with increasing equivalence ratio; this is due to the increase in the flame length. The atomizing air ratio was found to have little influence on NOx emissions because the increase in the gas temperature in the holder produced by an increase in the atomizing air ratio balances the corresponding decrease in flame length. The water contained in the emulsified fuel significantly reduces NOx emissions because of the reduction in the gas temperature resulting from the latent heat of the water vapor. In addition, NOx scaling also revealed that when water is introduced, the dominant reaction mechanism of NOx production changes from the Zel’dovich mechanism to another mechanism, such as the prompt mechanism.