Damage associated with interactions between microstructural characteristics and hydrogen/methane gas mixtures of pipeline steels

There is no common standard for blended hydrogen use in the natural gas grid; hydrogen content is generally based on delivery systems and end-use applications. The need for a quantitative evaluation of hydrogen-natural gas mixtures related to the mechanical performance of materials is becoming increasingly evident to obtain long lifetime, safe, and reliable pipeline structures. This study attempts to provide experimental data on the effect of H₂ concentration in a methane/hydrogen (CH₄/H₂) gas mixture used in hydrogen transportation. The mechanical performance under various blended hydrogen concentrations was compared for three pipeline steels, API X42, X65, and X70. X65 exhibited the highest risk of hydrogen-assisted crack initiation in the CH₄/H₂ gas mixture in which brittle fractures were observed even at 1% H₂. The X42 and X70 samples exhibited a significant change in their fracture mechanism in a 30% H₂ gas mixture condition; however, their ductility remained unchanged. There was an insignificant difference in the hydrogen embrittlement indices of the three steels under 10 MPa of hydrogen gas. The coexistence of delamination along with the ferrite/pearlite interface, heterogeneous deformation in the radial direction, and abundance of nonmetallic MnS inclusions in the X65 sample may induce a high stress triaxiality at the gauge length at the beginning of the slow strain rate tensile process, thereby facilitating efficient hydrogen diffusion.     

Influence of high pressure hydrogen on the tensile and fatigue properties of a high strength Cu–Al–Ni–Fe alloy

Aluminum bronze CW307G was tensile and fatigue tested in 10 MPa hydrogen, 10 MPa helium and 0.1 MPa air atmosphere. Neither tensile nor S–N fatigue properties were affected when testing in H₂. Fractography on the fatigue specimens revealed similar striation morphology on the specimens tested in H₂ and He. Dissociative chemisorption as well as hydrogen absorption were identified as potential rate limiting processes being responsible for the impassivity to HEE of this alloy.     

Fracture toughness properties of HIC susceptible carbon steels in sour service conditions

Hydrogen Induced Cracking (HIC) in carbon steels is a well-studied mechanism, where diffusing hydrogen atoms accumulates at the steel imperfections/laminations to create gaseous hydrogen with very high pressure, leading to initiation and growth of internal cavities, so-called HIC. Measurements of relevant fracture toughness properties of non-HIC resistant steels in hydrogen environment is critical to predict and assess the initiation and growth of HIC. The present work attempts to quantify the effect of hydrogen on the fracture toughness properties (K_Q and CTOD) of an API X42 pipeline steel under simulated H₂S in-service conditions. The fracture toughness properties are measured in TL and SL directions: perpendicular and parallel to the pipeline wall thickness, respectively, following ASTM E1820, standard. Since the X42 is a non-HIC resistant steel, the measurement of the fracture toughness properties in the SL direction is more relevant in terms of HIC initiation and growth than fracture toughness properties in the TL direction. Indeed, parallel to the thickness of the pipeline wall, X42 steel shows microstructural features prone to HIC formation and growth. Steady state H₂S in-service conditions were simulated by charging the specimen for 48 h using a special electrolytic solution and then tested (ex-situ) to evaluate the fracture toughness properties. The steady state H₂S environment was obtained by measuring the Hydrogen Concentration (CH) in the bulk of the specimen, using Thermal desorption Spectroscopy at three levels of CH. It was observed that the K_Q was not affected in the SL direction, while it was reduced in the TL direction for 1.5 ppmw of CH. The CTOD showed mixed results in the TL direction while it was significantly reduced in the SL direction reaching a saturation at 1 ppmw of CH. Besides, microstructural analyses showed that the presence of inclusions coalescence in form of dimples promote the early failure, which is more pronounced in the hydrogen environment especially at higher levels of CH.     

Effect of hydrogen on fracture toughness properties of a pipeline steel under simulated sour service conditions

The effect of hydrogen on the fracture toughness properties of an API X65 pipeline steel is studied under simulated H₂S in-service conditions. The fracture toughness properties are measured in LT and SL directions (perpendicular and parallel to the pipeline wall thickness, respectively), following ASTM E1820. Due to size restrictions of standard single edge notch bending (SEB) specimens at the direction parallel to the thickness of the pipeline wall, an experimental protocol (see the patent) was developed to carry out the fracture toughness tests, while complying with ASTM standard 1820. This approach is especially useful in situations where hydrogen induced cracking (HIC) and in a broader sense, stepwise cracking takes place, since these cracks initiate and grow primarily in planes parallel to the pipeline rolling plane. Such values of fracture toughness are often different from those commonly measured in planes perpendicular to the rolling plane. Hydrogen might not have the same effect on fracture toughness properties as measured in different directions, due to microstructural features which are inherent from steel manufacturing process. The steady state H₂S in-service conditions are simulated by electrolytically charging the specimen, for 48 h and then testing (ex-situ) the specimen for evaluating the fracture toughness properties. The steady state H₂S environment charging was obtained by measuring the hydrogen concentration in the bulk of the specimen through thermal desorption spectroscopy (TDS) at three levels of hydrogen concentration. It was observed that the K_Q was moderately decreased with increasing hydrogen concentration in the bulk of the steel, while CTOD₀ showed a significant reduction with increasing hydrogen concentration.     

Influence of hydrogen on the microstructure and fracture toughness of friction stir welded plates of API 5L X80 pipeline steel

In this work, the influence of hydrogen on the microstructure and fracture toughness of API 5L X80 high strength pipeline steel welded by friction stir welding was assessed. Samples were hydrogenated at room temperature for a duration of 10 h in a solution of 0.1 M H₂SO₄ + 10 mg L⁻¹ As₂O₃, with an intensity current of 20 mA cm⁻². Fracture toughness tests were performed at 0 °C in single-edged notched bending samples, using the Critical Crack Tip Opening Displacement (CTOD) parameter. Notches were positioned in different regions within the joint, such as the stir zone, hard zone, and base material. Hydrogen induces internal stress between bainite packets and ferrite plates within bainite packets. Besides, hydrogen acted as a reducer of the strain capacity of the three zones. The base metal had a moderate capacity to resist stable crack growth, displaying a ductile fracture mechanism. While the hard zone showed a brittle behavior with CTOD values below the acceptance limits for pipeline design (0.1–0.2 mm). The fracture toughness of the stir zone is higher than that of the base metal. Nevertheless, the stir zone displayed higher data dispersion due to its high inhomogeneity. Hence, it can also show a brittle behavior with critical CTOD values.     

Hydrogen environment embrittlement of an ODS RAF steel – Role of irreversible hydrogen trap sites

The microstructure and the effects of 10 MPa hydrogen atmosphere on the tensile properties of a oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steel were investigated. The microstructure consists of a fine grained ferritic matrix with Me₃O₄ (Me = Cr, Fe or Mn), VN and Cr₂₃C₆ grain boundary precipitates as well as dispersed yttrium oxide nano precipitates in the ferritic matrix. The yield and ultimate tensile strength were unaffected by the H₂ atmosphere whereas elongation at fracture and reduction in area were markedly reduced. In H₂ atmosphere, the fracture morphology was found to be a mixture of intergranular H-assisted fracture and a smaller amount of transgranular hydrogen enhanced localized plasticity (HELP) fracture. The sensitivity of the ODS RAF steel to hydrogen embrittlement is attributed to the large number grain boundary precipitates which enhance the tendency for intergranular fracture.     

Thermodynamic characterization of the (H2 + C3H8) system significant for the hydrogen economy: Experimental (p, ρ, T) determination and equation-of-state modelling

For the gradual introduction of hydrogen in the energy market, the study of the properties of mixtures of hydrogen with typical components of natural gas (NG) and liquefied petroleum gas (LPG) is of great importance. This work aims to provide accurate experimental (p, ρ, T) data for three hydrogen-propane mixtures with nominal compositions (amount of substance, mol/mol) of (0.95H₂ + 0.05C₃H₈), (0.90H₂ + 0.10C₃H₈), and (0.83H₂ + 0.17C₃H₈), at temperatures of 250, 275, 300, 325, 350, and 375 K, and pressures up to 20 MPa. A single-sinker densimeter was used to determine the density of the mixtures. Experimental density data were compared to the densities calculated from two reference equations of state: the GERG-2008 and the AGA8-DC92. Relative deviations from the GERG-2008 EoS are systematically larger than those from the AGA8-DC92. They are within the ±0.5% band for the mixture with 5% of propane, but deviations are higher than 0.5% for the mixtures with 10% and 17% of propane, especially at low temperatures and high pressures. Finally, the sets of new experimental data have been processed by the application of two different statistical equations of state: the virial equation of state, through the second and third virial coefficients, B(T, x) and C(T, x), and the PC-SAFT equation of state.     

Notched-tensile properties under high-pressure gaseous hydrogen: Comparison of pipeline steel X70 and austenitic stainless type 304L, 316L steels

The effect of high-pressure gaseous H₂ on the fracture behavior of pipeline steel X70 and austenitic stainless steel type 304L and 316L was investigated by means of notched-tensile tests at 10 MPa H₂ gas and various test speed. The notch tensile strength of pipeline X70 steel and austenitic stainless steels were degraded by gaseous H₂, and the deterioration was accompanied by noticeable changes in fracture morphology. The loss of notch tensile strength of type 316L and X70 steels was comparable, but type 304L was more susceptible to hydrogen embrittlement than the others. In the X70 steel, hydrogen embrittlement increased as test speed decreased until the test speed reached 1.2 × 10^?3 mm/s, but the effect of test speed was not significant in 304L and 316L steels.     

Hydrogen permeation studies of composite supported alumina-carbon molecular sieves membranes: Separation of diluted hydrogen from mixtures with methane

One alternative for the storage and transport of hydrogen is blending a low amount of hydrogen (up to 15 or 20%) into existing natural gas grids. When demanded, hydrogen can be then separated, close to the end users using membranes. In this work, composite alumina carbon molecular sieves membranes (Al-CMSM) supported on tubular porous alumina have been prepared and characterized. Single gas permeation studies showed that the H₂/CH₄ separation properties at 30 °C are well above the Robeson limit of polymeric membranes. H₂ permeation studies of the H₂–CH₄ mixture gases, containing 5–20% of H₂ show that the H₂ purity depends on the H₂ content in the feed and the operating temperature. In the best scenario investigated in this work, for samples containing 10% of H₂ with an inlet pressure of 7.5 bar and permeated pressure of 0.01 bar at 30 °C, the H₂ purity obtained was 99.4%.     

Evaluation of hydrogen concentration effect on the natural gas properties and flow performance

The natural gas flowing through transmission pipeline is impure and has a wide range of non-hydrocarbons components at different concentrations like hydrogen. The presence of hydrogen in the natural gas mixture influences its properties and flow performance. The effect of hydrogen concentration on the natural gas flowing through a transportation pipeline has not been adequately investigated and widely comprehended. In this paper, several mixtures flow through pipeline include typical natural gas and hydrogen at different concentrations up to 10% are evaluated to demonstrate their impact on the flow assurance and the natural gas properties. The string Ruswil – Griespass part from the Transitgas project with 94 km length is simulated applying Aspen Hysys Version 9 and validated using Aspen Plus. The simulation specifications were 1.228 1 10⁶ kg/h mass flowrate, 1200 mm and 1164 mm the outer and inner diameters, and 75 bar and 29.4 °C operating pressure, and temperature. The effect of different hydrogen concentrations has been examined and the differences from the typical mixture are estimated. The results show that the presence of hydrogen in the natural gas mixture reduces its density, 10% hydrogen content records 11.78% reduction in the density of typical natural gas. Interestingly, it has been found that up to 2% of hydrogen concentration turns in elevating the viscosity of the typical natural gas while the viscosity decreases at the point that hydrogen content increases above 2%. In addition, the pressure losses over the transmission pipeline increases due to the presence of hydrogen, 10% hydrogen concentration turns in 5.39% increase in the pressure drop of the natural gas mixture. Also, the temperature drop across the pipeline decreases as the hydrogen concentration increases; 10% hydrogen content can result in a 6.14% reduction in the temperature drop across the pipeline. As well as, the findings prove that the hydrogen strongly impacts the phase envelope by changing from size symmetric to size asymmetric diagram. The effect of pipeline elevations has been investigated by changing the elevation up to 25 m uphill and 25 m downhill. The results state that increase the pipeline elevation turns in increasing the pressure losses over the pipeline length. Along with this, the results illustrate that the presence of hydrogen in the mixture elevates the critical pressure and reduces the critical temperature.     

Effects of CH4 and CO on hydrogen embrittlement susceptibility of X80 pipeline steel in hydrogen blended natural gas

The slow strain rate tensile experiments are carried out to investigate the tensile properties of X80 pipeline steel in hydrogen blended natural gas environments with different H₂/CH₄/CO contents. Mechanical properties and fracture morphologies are further analyzed. The results show that the hydrogen embrittlement susceptibility of X80 steel can be inhibited by the presence of CH₄/CO, and the inhibition mechanisms are discussed. When the CH₄ contents increase above 20 vol%, the inhibition on hydrogen embrittlement of X80 steel is stabilized. By comparison, the inhibitory effect of CO is more significant.     

Flow process and energy release of hydrogen in fluorine

Hydrogen is a clean energy source and fluorine is a strong oxidant. The chemical reaction between the two will make the utilization of hydrogen energy significantly improved, which is a new way to develop and utilize hydrogen energy. In this study, the ANSYS Fluent software is used to solve the reaction kinetics process, which has great advantages in the simulation of combustion and chemical reaction flow, and Computational fluid dynamics (CFD) adopts numerical methods to solve the Navier-Stokes (N–S) partial differential equation. Here, the CFD code ANSYS Fluent is performed to calculate the two-dimensional compressible reaction flow, therefore, we use the methods to explore the flow process and reaction energy release of hydrogen in fluorine and a new ways of hydrogen energy development is explored. The initial stage of the explosion for F₂ filling into H₂/air in the pipeline is volatile. Chemical reactions for F₂ filling into H₂/air in the pipeline interact with flows for F₂ filling into H₂/air in the pipeline. Energy release of hydrogen in fluorine depends on the flow and mixing process. When F₂ is filled into a premixed H₂/air in the pipeline with a length of 0.9 m and a diameter of 0.1 m, the explosion pressure reaches 0.307MPa–0.408 MPa and the explosion temperature reaches 2698 K–3107 K. The explosion reaction is very rapid and only takes about 40 ms to reach equilibrium. The higher the incident pressure at the pressure inlet, the smaller the peak pressure and temperature are, when the reaction reaches equilibrium.     

Study on the difference of dispersion behavior between hydrogen and methane in utility tunnel

Compared to liquid/gas hydrogen tank, the pipeline is an economical way for hydrogen transportation. With the quick development of utility tunnel in China, hydrogen pipeline enters the gas compartment can be expected soon. However, all the safety requirements of the gas compartment in the current standards are designed for natural gas, and the applicability for hydrogen is unknown. Therefore, a series of studies were started to investigate the safety of hydrogen in utility tunnel. In this work, a real utility tunnel locates at Shanghai was selected as the physical object. A 3D numerical model was built and successfully validated by a scaled tunnel test. The model has the maximum deviation of +9.5%. After that, a comparatively study of the dispersion behavior of CH₄ and H₂ was conducted. The assumed scenario was a 20 mm small-hole leaks with gauge pressure of 1.0 MPa in the middle of the tunnel. Numerical results shown that, H₂ has a larger dispersion velocity and higher concentration, and is more dangerous compared to CH₄. The current emergency ventilation strategy of air change rate of 12 times/h is not effective enough to dilute the H₂ flammable cloud. The alarm time of the testing points shown strong linear law. There was a sharp variation in the range of 20%–100% LFL (Lower Flammable Limit), so the alarm strategy in the tunnel standards is too ideal for both CH₄ and H₂. The numerical results in the present study could provide a guidance for the design and safety management of the hydrogen tunnel.     

Separation of H2/CH4 gas mixture through graphenylene membrane with functionalized nanopore: A computational study

Using molecular dynamics (MD) simulations, we investigated the performance of graphenylene membrane with functionalized nanopore in the H₂/CH₄ separation. In the present work, we studied the impact of functionalized nanopore, system temperature (298, 323, and 348 K), applied difference pressure (up to 2 MPa), and feed composition on the H₂/CH₄ separation performance. The passage of gas molecules across the nanopore was monitored within the simulations, and the permeance was determined under applied conditions. The results revealed that the size of gas molecules and its interaction with the membrane nanopore are two important factors in the separation performance of H₂/CH₄ gas mixture. It is also found that H₂ molecules can easily pass through the studied membranes, whereas no CH₄ molecule was seen in the permeate side, which confirms the ultrahigh selectivity of H₂ over CH₄. Furthermore, the maximum H₂ permeance of 1.95 × 10⁵ GPU through the pore 1 was obtained at 1.5 MPa, which was higher than that of 1.93 × 10⁵ GPU through pore 2. The results also demonstrated that the system temperature doesn't have any effect on the membrane performance. To this end, the permeance of H₂ molecules through the studied membranes obviously increased with raising the ration of H₂ molecules in the feed composition. Due to high selectivity and permeance, the graphenylene membrane with functionalized nanopore is expected to have promising applications in hydrogen separation from H₂/CH₄ mixed gas.     

A mixed electronic and protonic conducting hydrogen separation membrane with asymmetric structure

In this work, highly doped ceria with lanthanum, La_0.5Ce_0.5O_2−δ (LDC), are developed as hydrogen separation membrane material. LDC presents a mixed electronic and protonic conductivity in reducing atmosphere and good stability in moist CO₂ environment. LDC separation membranes with asymmetrical structure are fabricated by a cost-saving co-pressing method, using NiO + LDC + corn starch mixture as substrate and LDC as top membrane layer. Hydrogen permeation properties are systemically studied, including the influence of operating temperature, hydrogen partial pressure in feed stream and water vapor in both sides of the membrane on hydrogen permeating fluxes. Hydrogen permeability increases as the increasing of temperature and hydrogen partial pressure in feed gas. Using 20% H₂/N₂ (with 3% of H₂O) as feed gas and dry high purity argon as sweep gas, an acceptable flux of 2.6 × 10⁻⁸ mol cm⁻² s⁻¹ is achieved at 900 °C. The existing of water in both sides of membrane has significant effect on hydrogen permeation and the corresponding reasons are analyzed and discussed.     

Molecular simulation of methane steam reforming reaction for hydrogen production

By means of advanced techniques of molecular simulations, we have studied the chemical equilibrium of methane steam reforming reaction. We have computed the conversion of CH₄, yield and selectivity of H₂, etc. in the gas phase by reactive canonical Monte Carlo (RCMC) method and compared with those from Gibbs energy of formation method. The consistency of the two methods encourages us to use the RCMC method to optimize the operating conditions. We found that under low pressure 0.1 MPa, high temperature 1073 K and high water-gas ratio H₂O/CH₄ = 5, the CH₄ conversion, H₂ yield and selectivity were the highest, with the values of 99.93%, 3.51 mol/molCH₄ and 99.98%, respectively. In addition, the pore size of activated carbon significantly affects the chemical equilibrium composition in the pores. Since low pressure and high temperature are not conducive to the adsorption of reactive components by activated carbon, the chemical balance in the pores cannot be improved. At 773 K, 3.0 MPa and pore width is less than 2 nm, the pores are mainly occupied by CH₄ and H₂O reactant molecules. Further increasing the temperature can increase the H₂ content in the pores, but the adsorption capacity in the pores will decrease. We use activated carbon to adsorb and separate CO and H₂ (CO:H₂ = 1:3), the main components after the gas phase reaction reaches equilibrium. At 298 K, 7.5 MPa and the optimal pore width of 0.76 nm, the CO/H₂ selectivity is 28.3 and the CO adsorption capacity is 8.45 mmol/cm³.     

Hydrogen embrittlement of the coarse grain heat affected zone of a quenched and tempered 42CrMo4 steel

The coarse grain heat affected zone (CG-HAZ) of welds produced in a quenched and tempered 42CrMo4 steel was simulated by means of a laboratory heat treatment consisting in austenitizing at 1200 °C for 20 min, oil quenching and finally applying a post weld heat treatment at 700 °C for 2 h (similar to the tempering treatment previously applied to the base steel). A tempered martensite microstructure with a prior austenite grain size of 150 μm and a hardness of 230 HV, similar to the aforementioned CG-HAZ weld region, was produced. The effect of the prior austenite grain size on the hydrogen embrittlement (HE) behaviour of the steel was studied comparing this coarse-grained microstructure with that of the fine-grained base steel, with a prior austenite grain size of 20 μm.The specimens used in this study were charged with hydrogen gas in a reactor at 19.5 MPa and 450 °C for 21 h. Cylindrical specimens were used to determine hydrogen uptake and hydrogen desorption behaviour. Smooth and notched tensile specimens tested under different displacement rates were also used to evaluate HE.Embrittlement indexes, EI, were generally quite low in the case of hydrogen pre-charged tensile tests performed on smooth tensile specimens. However, very significant embrittlement indexes were obtained with notched tensile specimens. It was observed that these indexes always increase as the applied displacement rate decreases. Moreover, hydrogen embrittlement indexes also increase with increasing prior austenite grain size. In fact, the embrittlement index related to the reduction in area, EI_(RA), reached values of over 20% and 50% for the fine and coarse grain size steels, respectively, when tested under the lowest displacement rates (0.002 mm/min).A comprehensive fractographic analysis was performed and the main operative failure micromechanisms due to the presence of internal hydrogen were determined at different test displacement rates. While microvoids coalescence (MVC) was found to be the typical ductile failure micromechanism in the absence of hydrogen in the two steels, brittle decohesion mechanisms (carbide-matrix interface decohesion, CMD, and martensitic lath interface decohesion, MLD) were observed under internal hydrogen. Intergranular fracture (IG) was also found to be operative in the case of the coarse-grained steel tested under the lowest displacement rate, in which hydrogen accumulation in the process zone ahead of the notch tip is maximal.     

Hydrate-based separation of the CO2 + H2 mixtures. Phase equilibria with isopropanol aqueous solutions and hydrogen solubility in CO2 hydrate

The gas hydrates' ability to preferentially bind one of the components of a gas mixture into a hydrate state makes it possible to consider hydrate-based technology as promising for the separation of gas mixtures. When a hydrate is obtained from a gas mixture, mixed hydrates with a complex composition inevitably occur. Issue of their composition determination stays apart. This a rather difficult task, which is complicated by the dissolution of small molecules such as hydrogen in the hydrate phase. This, in turn, impedes the analysis of the data obtained. In this work, the solubility of hydrogen in carbon dioxide hydrate in the range of 269.7–275.7 K and at partial H₂ pressure up to 4.5 MPa was experimentally determined. Hydrate composition was found to be CO₂·(0.01X)H₂·6.5H₂O at H₂ pressure of X MPa. The equilibrium conditions of hydrates formation in the systems of H₂O – CO₂ – H₂ and H₂O – 2-propanol – CO₂ – H₂ were also determined in a wide range of hydrogen concentrations. Hydrogen seems to be an indifferent diluent gas regarding CO₂ hydrate equilibrium pressure. The compositions of the equilibrium phases have been determined as well. It was shown that isopropanol does not form a double hydrate with СО₂, only sI СО₂ hydrate occurred in the studied systems. The obtained dependencies will be useful in analyzing the process of СО₂ + Н₂ gas mixtures separation by the hydrate-based method.     

Improvement of hydrogen-separating performance by on-stream catalytic cracking of silane over hollow fiber MFI zeolite membrane

MFI zeolite membranes were synthesized on porous α-alumina hollow fibers by in-situ hydrothermal synthesis. The membranes were further modified for H₂ separation by on-stream catalytic cracking deposition of methyldiethoxysilane (MDES) in the zeolitic pores. The separation performance of the modified membranes was characterized by separation of H₂/CO₂ gas mixture at 500 °C. Activation of MFI zeolite membranes by air at 500 °C was found to promote catalytic cracking deposition of silane in the zeolitic pores effectively, which resulted in significant improvement of H₂-separating performance. The H₂/CO₂ separation factor of 45.6 with H₂ permeance of 1.0 × 10⁻⁸ mol m⁻² s⁻¹ Pa⁻¹ was obtained at 500 °C for a modified hollow fiber MFI zeolite membrane. The as-made membranes showed good thermochemical stability for the separation of H₂/CO₂ gas mixture containing H₂O and H₂S, respectively.     

Effects of hydrogen addition on the combustion characteristics of diesel fuel jets under ultra-high injection pressures

Many applications use hydrogen addition and high-pressure fuel injection technology to improve combustion performance. In this study, spray atomization and combustion characteristics of a diesel fuel jet, under the injection pressure of 350 MPa, injecting into a constant volume combustion vessel filled with air-hydrogen mixture at the diesel engine relevant condition are investigated by simulation method. A simplified mechanism of the n-heptane (C₇H₁₆) oxidation chemistry mechanism consisting of 26 reactions and 25 species integrated with the Kéromnès-2013 hydrogen combustion mechanism and EDC combustion model are utilized to predict the diesel fuel spray auto-ignition and combustion. The ambient gas is the mixture of air and hydrogen range in volume fraction from 0% to 10%. The ambient temperature and pressure is set to 1000 K and 3.5 MPa, respectively. The results indicate that as the hydrogen volume fraction is 2%, the minimum overall droplet SMD (Sauter Mean Diameter) is approximately 0.95 μm, which is obviously smaller than that of the case with the conventional high injection pressure. In cases that H₂ v/v% larger than 4%, the maximum gaseous temperature increased significantly up to 2700 K. There are two peaks in the temperature growth rate curves as the hydrogen fraction of 8% and 10%. The high temperature at the outer edge of the spray is clearly seen due to its high value when the hydrogen fraction is larger than 4%. The hot reaction layer is the main location of CO formation. The H, OH radicals are formed at the edge of the spray where the temperature is high. The hydrogen species obviously promotes the oxidation and combustion of diesel fuel.