Atmospheric Pressure Conditions Research Articles

Wave mode observation of hydrogen/oxygen driven rotating detonations in the hollow and annular rotating detonation rocket engine

The rotating detonation rocket engine (RDRE) fueled by hydrogen/oxygen propellant represents a promising propulsion technology due to its high thermodynamic efficiency and propellant superior specific impulse. The rotating detonation wave (RDW) must propagate in a specific propagation mode while maintaining the self-sustaining state to ensure stable operation. An experimental system of hydrogen/oxygen fueled RDRE was developed in the present study. The operation of RDRE and propagation mode of RDW were investigated under atmospheric pressure conditions, and both hollow and annular combustors were tested. The high-frequency pressure fluctuations in the RDRE were measured by the dynamic pressure transducer, while a high-speed camera was used to capture images of flame luminescence at the rear end of the RDRE. The experimental results showed that the RDW could be initiated and reached a self-sustaining propagation state with hydrogen/oxygen propellant in the hollow and annular RDRE. A single-wave mode, a two-wave co-rotating mode, and a three-wave co-rotating mode were visualized under different conditions. With the increase in the equivalence ratio, the number of rotating detonation fronts decreased, and the variations in the RDW propagation modes were consistent in the hollow and annular RDRE. However, when the equivalence ratio exceeds 1.2, the propagation velocity decreases sharply in the annular combustor, while in the hollow combustor the RDW propagates stably, revealing a higher upper limit for the equivalence ratio. Also, the dominant frequency distribution was more concentrated in the hollow combustor. The findings provide valuable insight into the variations in detonation modes related to the equivalence ratio and combustor configuration.

DFT investigation of thermodynamic, electronic, optical, and mechanical properties of XLiH3 (X= Mg, Ca, Sr, and Ba) hydrides for hydrogen storage and energy harvesting

The present study investigates the hydrogen storage capacity and physical properties of the perovskite hydrides XLiH3 (X = Mg, Ca, Sr, and Ba). The studied compounds MgLiH3, CaLiH3, SrLiH3, and BaLiH3 have lattice constants 3.76, 4.29, 4.64, and 5.04 Å, respectively. These compounds are also observed to be stable in cubic phase under atmospheric pressure and temperature conditions. They have hydrogen storage capacities 8.76 wt%, 5.99 wt%, 3.07 wt%, and 2.03 %, respectively. The SrLiH3 compound has the greatest Debye temperature (θD) of 344.41 K. The analysis of the electronic band structure and density of states reveals that perovskite hydrides have semiconducting characteristics with indirect band gap values of 2.66, 2.34, 1.94, and 1.37 eV, respectively. The materials are semiconductors and have suitable band gaps to be utilized in optical devices. Therefore, the optoelectronic properties of dielectric constants, absorption, and energy loss have been determined to predict the potential of materials for optoelectronic applications. Furthermore, the elastic constants, moduli, and anisotropy are also calculated for the observed materials. The Possion and Pugh ratios indicate these compounds exhibit ductile behaviour and significant anisotropy. Therefore, large values of hydrogen capacities, stabilities, and extraordinary physical behaviour make them important for hydrogen storage systems.

Diffusive solubility of nitrogen in Propane: Measurement from 96 K to 227 K at 0.1 MPa

The burgeoning demand for large-scale energy storage has catalyzed the advancement of Liquid Air Energy Storage (LAES) technology. However, the liquid-phase propane cold storage process in LAES systems encounters a significant challenge: the dissolution of nitrogen protection gas in propane poses a substantial risk to both operational safety and performance. Given the dearth of data on the diffusive solubility of nitrogen in propane under constant atmospheric pressure and low-temperature conditions, this study constructed a testbench and conducted experiments within a temperature range of 96–227 K at a pressure of 0.1 MPa. The molar diffusive solubilities at 227 K, 176 K, 139 K, and 96 K are 0.030 %, 0.177 %, 0.297 %, and 0.962 %, respectively. Besides, this study also fits a calculation equation for the diffusive solubility of nitrogen in propane, which applies to the propane cold storage process in LAES systems.

Analysis of unstable combustion caused by the Gas–Liquid two-phase flow in small hypergolic propellant engines

Hypergolic bipropellant engines are extensively used in spacecraft operations. In these engines, the combustion reaction is initiated by the impinging jets of the oxidizer and fuel in the liquid phase. The most commonly used hypergolic fuels, hydrazine and monomethylhydrazine, as well as the oxidizer, nitrogen tetroxide, are all in liquid state under room temperature and atmospheric pressure conditions. However, as these engines are operated in a space vacuum, a portion of the propellant inevitably evaporates because of low-pressure boiling immediately after engine start-up. The mixing of gas with liquid propellant results in unstable combustion, and minimizing this effect is critical for the engine design. Particularly, preventing high-frequency combustion instability is essential as it can be detrimental to the engine. This paper presents a mechanism that activates high-frequency combustion instability, realized by analyzing the pressure within the combustion chamber during artificially induced unstable combustion. Furthermore, the methodology for establishing operational constraints based on the proposed mechanism is clarified, along with the method for collecting test data. The study findings provide important indicators for the design criteria of bipropellant engines, contributing to the diversification and complexity of space development programs.

Experimental study on coal oxidation and temperature rise under different air leakage modes due to atmospheric pressure changes

ABSTRACT The spontaneous combustion of residual coal in enclosed goafs may induce coupled thermodynamic disasters with severe consequences. To study the dynamic characteristics of coal oxidation and temperature increase in an enclosed goaf under varying atmospheric pressure conditions, the air leakage model was analyzed through theoretical derivation. The resistance, temperature, and CO concentration during coal oxidation under different air leakage modes were further studied using a self-built experimental system. The results indicated three air leakage modes of coal oxidation in an enclosed goaf: constant, intermittent, and reciprocating. The resistance of the three modes increased from 5 Pa to 7 Pa with time. Compared to constant air leakage, the time of resistance change was advanced by 1428 s and 1897 s under intermittent and reciprocating air leakage, respectively. Additionally, both intermittent and reciprocating air leakage promote coal oxidation and produce higher CO levels compared to constant air leakage. However, intermittent air leakage is more likely to produce higher temperature points, while reciprocating air leakage is more likely to cause large areas of coal oxidation. The order of the promoting effect of the intermittent and reciprocating half cycle on coal oxidation is 60 s, 300 s, 600 s, and 1200 s. These results are significant for understanding coal spontaneous combustion and efficiently managing enclosed goafs.

CFD Analyses of Density Gradients under Conditions of Supersonic Flow at Low Pressures.

This paper deals with CFD analyses of the difference in the nature of the shock waves in supersonic flow under atmospheric pressure and pressure conditions at the boundary of continuum mechanics for electron microscopy. The first part describes the verification of the CFD analyses in combination with the experimental chamber results and the initial analyses using optical methods at low pressures on the boundary of continuum mechanics that were performed. The second part describes the analyses on an underexpanded nozzle performed to analyze the characteristics of normal shock waves in a pressure range from atmospheric pressure to pressures at the boundary of continuum mechanics. The results obtained by CFD modeling are prepared as a basis for the design of the planned experimental sensing of density gradients using optical methods, and for validation, the expected pressure and temperature courses from selected locations suitable for the placement of temperature and pressure sensors are prepared from the CFD analyses.

Experimental study on effect of pressure on ADS-4 liquid entrainment characteristics in T-junction

Liquid entrainment phenomenon can occur in the T-junction formed by the vertical ADS-4 pipeline and the hot pipe section during SBLOCA process in AP1000 reactor. At present, most of the studies on the liquid entrainment phenomenon in T-junction with large branch pipe concentrate on the atmospheric pressure condition, which is difficult to accurately reflect the real state of the accident process. The liquid entrainment experiments were carried out at 0.1–0.4 MPa on ADETEL facility. The results show that there will be obvious reverse flow phenomenon in the branch at 0.1 MPa and the phenomenon disappears gradually with the increase of pressure. Furthermore, the occurrence of intermittent two-phase slug flow in the horizontal tube was observed at lower pressures. As pressure increases, the entrainment process will become more continuous and stable, with a concomitant reduction in intermittency. The steady-state entrainment liquid level and the onset of entrainment liquid level both decrease with increasing pressure, indicating that increasing pressure can facilitate the liquid entrainment amount. The existing correlations cannot accurately estimate the entrainment amount during SBLOCA in nuclear reactor with a deviation of more than +100% between the predictions and experimental data.

Studies of dynamic spatio-temporal processes of electrons in a 50 kHz/5 MHz dual-frequency dielectric barrier discharge plasma at atmospheric pressure

Dual-frequency excitation of dielectric barrier discharge (DBD) plasma reactors, where the plasma is generated by a low-frequency (LF) source and modulated by a radio-frequency (RF) source, have been widely adopted in the low-pressure regime. However, the impacts of the RF voltage and LF voltage amplitudes on the plasma parameters, including the spatiotemporal distributions of ion and electron densities, electron dynamics, and gas temperatures, remain poorly understood in the atmospheric pressure regime. The present work addresses this issue by conducting joint experimental and simulation studies for an atmospheric-pressure 50 kHz/5 MHz dual-frequency driven DBD plasma reactor based on phase-resolved optical emission spectra and a drift–diffusion model. The results demonstrate that the dynamic spatiotemporal behaviors of electrons change dramatically as the voltage of the RF component increases from 50 V to 300 V with the voltage of the LF component fixed at 1 kV. Moreover, the RF component is further demonstrated to modulate other plasma characteristics, such as particle densities, gas temperature, and argon emissions. These results contribute toward the tailoring of the non-equilibrium and nonlinear plasma parameters obtained under atmospheric pressure conditions.

The Enhancement Origin of Antioxidant Property of Carboxylated Lignin Isolated from Herbaceous Biomass Using the Maleic Acid Hydrotropic Fractionation.

Lignin is endowed with antioxidant activity due to its diverse chemical structure. It is necessary to explore the relationship between antioxidant activity and the chemical structure of the lignin to develop its high-value utilization. Herein, we employed maleic acid (MA) as a hydrotropic agent to preferably isolate the lignin from distinct herbaceous sources (wheat straw and switchgrass) under atmospheric pressure conditions. The resultant acid hydrotropic lignin (AHL) isolated from wheat straw exhibited high radical scavenging rates, up to 98% toward DPPH and 94% toward ABTS. Further investigations indicated that during the MA hydrotropic fractionation (MAHF) process, lignin was carboxylated by MA at γ-OH of the side-chain, providing additional antioxidant activity from the carboxy group. It was also found that the radical scavenging rate of AHL has a positive correlation with carboxyl, phenolic hydroxyl contents, and the S-G (syringyl-guaiacyl) ratio, which could be realized by increasing the MAHF severity. Overall, this work underlies the enhancement origin of the antioxidant property of lignin, which will facilitate its application in biological fields as an efficient, cheap, and renewable antioxidant additive.

Identification of the Problem in Controlling the Air–Fuel Mixture Ratio (Lambda Coefficient λ) in Small Spark-Ignition Engines for Positive Pressure Ventilators

The air–fuel ratio is a crucial parameter in internal combustion engines that affects optimal engine performance, emissions, fuel efficiency, engine durability, power, and efficiency. Positive pressure ventilators (PPVs) create specific operating conditions for drive units, characterized by a reduced ambient pressure compared to standard atmospheric pressure, which is used to control carburetor-based fuel supply systems. The impact of these conditions was investigated for four commonly used PPVs (with internal combustion engines) in fire services across the European Union (EU), using a lambda (λ), carbon dioxide (CO2), carbon monoxide (CO), and hydrogen carbon (HC) analyser for exhaust gases. All four ventilators were found to operate with lean and very lean mixtures, with their lambda coefficients ranging from 1.6 to 2.2. The conducted tests of the CO2, CO, and HC concentrations in the exhaust gases of all four fans show dependencies consistent with theoretical analyses of the impact of the fuel–air mixture on emissions. It can be observed that as the amount of burned air decreases, the values of CO and HC decrease, while the concentration of CO2 increases with the increase in engine load. Such an operation can accelerate engine wear, increase the emission of harmful exhaust gases, and reduce the effective performance of the device. This condition is attributed to an inadequate design process, where drive units are typically designed to operate within atmospheric pressure conditions, as is common for these engines. However, when operating with a PPV, the fan’s rotor induces significant air movement, leading to a reduction in ambient pressure on the intake side where the engine is located, thereby disrupting its proper operation.

Architecture of bimodal porous CuO/Al2O3-controlled continuous and low-temperature production of biomass-derived γ-butyrolactone

Biomedical activities of gamma butyrolactone (GBL) play an important role in the development of novel physiological and therapeutic agents. Maleic anhydride catalytic liquid phase hydrogenation allows for selective synthesis of GBL. However, this process is hampered by high cost noble metals and high reaction pressure conditions. Here, we demonstrate cyclic dehydrogenation of biomass-derived 1,4-butanediol (1,4-BDO) under atmospheric pressure and low-temperature conditions using highly dispersed and chemically stabilized Cu species on bimodal porous Al2O3. The bimodal porous Al2O3 exhibited both Lewis and Brønsted acidic properties along with high specific surface area and large pore volume. Among prepared catalysts, 15 wt% Cu/Al2O3 catalyst has shown an optimal crystallite size, bimodal porous nature, and high diffusion properties. Hence, high catalytic activity and remarkable GBL yields with very high 1,4-BDO conversion for 50 h of continuous time-on-stream. The unique bimodal textural properties help to enhance the dehydrogenation activity with a high turnover frequency (TOF) of about 5.0118 x 10-3 s-1via efficient chemical interaction between metallic Cu and 1,4-BDO molecules.

Hydrophobic deep eutectic solvents as novel media for the recycling of waste photovoltaic modules

Disposing of end-of-life photovoltaic (PV) modules has posed a significant environmental challenge due to the absence of proficient and sustainable recycling technologies. Separating PV modules, which are ethylene–vinyl acetate (EVA)-bonded layers, including glass, solar cells (i.e., silicon wafers), and backsheets, establishes a foundation for effectively reclaiming valuable resources from PV modules. Removing EVA encapsulation is critical for disassembling PV modules; nonetheless, effective and feasible technology is currently limited. Conventional EVA dissolving agents (e.g., benzene and trichloroethylene) are highly toxic and effective only for non-cross-linked segments of EVA. Thus, developing efficient and environmentally benign reagents for PV waste recycling is urgently needed. Herein, a novel recycling route employing deep eutectic solvents (DESs) with switchable hydrophilicity has achieved successful separation of the component layers within PV modules. Complete separation of the glass and backsheet bonded by the EVA film was achieved under atmospheric pressure and moderate temperature conditions (80 °C for 2 h) by hydrophobic DESs composed of menthol and decanoic acid ([Men][DecA] (1:1)). [Men][DecA] effectively induced EVA swelling, concurrently accelerating EVA dissolution by substituting the acetate groups in the side chains of EVA with the hydroxyl groups of the DES. The superior PV module disintegration can be attributed to the exceptional EVA dissolution ability of the [Men][DecA] framework, and the achieved high solid–liquid ratio (40 g/L) for EVA in [Men][DecA] is beneficial for industrial processes. Furthermore, the reusability of [Men][DecA], which is endorsed by its switchable hydrophilicity, introduces a sustainable platform for PV module disintegration, thereby facilitating the large-scale recycling of PV waste.

Analysis of the thermodynamic performance of the SOFC-GT system integrated solar energy based on reverse Brayton cycle

Efficient power generation systems are an essential way to reduce carbon emissions. To avoid the complex effects of high-pressure conditions on the solid oxide fuel cell (SOFC) and gas turbine (GT) hybrid systems, while further improving energy efficiency. A SOFC-GT hybrid system based on the reverse Brayton cycle (RBC) is proposed, in which the SOFC operates at near atmospheric pressure conditions and GT expands below atmospheric pressure. Solar energy is integrated to further enhance system performance. Rigorous assessments of the novel system and the pressurized system are conducted utilizing energy, exergy and economic analysis. The sensitivity analysis of environmental parameters on the novel system's performance is performed. The results show that the novel system generates power and efficiency better than the conventional system when the GT compression ratio is 3 and 6, respectively. The power generation and exergy efficiency of the novel system at the design point is 60.47 % and 58.57 %, respectively. The largest exergy destruction occurred in the SOFC. The lowest exergy efficient components are the parabolic dish collector (PDC) and heat exchanger 2. The novel system is more cost-effective due to the higher lifetime of the SOFC, with the levelized cost of energy (LCOE) is 0.1418 $/kWh.

Engineering the functionality of porous organic polymers (POPs) for metal/cocatalyst-free CO2 fixation at atmospheric conditions

Carbon dioxide (CO2) utilization as C1 feedstock under metal/co-catalyst-free conditions facilitates the development of eco-friendly routes for mitigating atmospheric CO2 concentration and producing value-added compounds. In this regard, herein, we designed a bifunctional porous organic polymer (POP-1) by incorporating acidic (-CONH) and CO2-philic (-NH/N) sites by judicious choice of organic precursors. Indeed, POP-1 exhibits high heat of interaction for CO2 (40.2 kJ/mol) and excellent catalytic performance for transforming carbon dioxide to cyclic carbonates, a high-value commodity chemical with high selectivity and yield under metal/cocatalyst/solvent-free atmospheric pressure conditions. Interestingly, an analogous polymer (POP-2) that lacks basic (-NH/N) sites showed lower CO2 interaction energy (31.6 kJ/mol) and catalytic activity than that of POP-1. The theoretical studies further supported the superior catalytic activity of POP-1 in the absence of Lewis acidic metal and cocatalyst. Notably, POP-1 showed excellent reusability with retention of catalytic performance for multiple cycles of usage. Overall, this work presents a novel approach to metal/cocatalyst/solvent-free utilization of CO2 under eco-friendly atmospheric pressure conditions.

Synthesis of nitrogen-doped crystalline Ga2O3 thin films via trimethylgallium doped NH3/H2/N2/O2 premixed stagnation flames

This study presents a novel and cost-effective technique for fabricating nitrogen-doped crystalline α-Ga2O3 and β-Ga2O3 thin films under atmospheric pressure conditions through flame synthesis for the first time. We employ metal–organic ammonia (NH3)-assisted flame synthesis (MO-NAFS) in a quasi-one-dimensional trimethylgallium (TMG) doped NH3/H2/N2/O2 flat flame to achieve a one-step deposition of Ga2O3 onto c-plane α-Al2O3 substrates. We found that hydrogen (H2) addition directly impacts the crystallinity of the Ga2O3 thin film. When only NH3 is employed as the fuel, a thin-film single-crystal nitrogen-doped β-Ga2O3 was observed. Blending the NH3 with 5 % of H2 yields a single-crystal nitrogen-doped α-Ga2O3, while a further increase of H2 fraction up to 10 % results in a mixture of both α-Ga2O3 and β-Ga2O3 crystals. Remarkably, the nitrogen doping through MO-NAFS was found to persistently result in an N/O atomic ratio as high as 1.12, as determined by the XPS analysis. This approach paves the way to a simple and scalable means for producing crystalline nitrogen-doped Ga2O3 thin films with potential control of crystal phase composition through parameter adjustments.

Suppression effects of different extinguishing agents on vent gases fires from lithium-ion batteries after thermal runaway: A comprehensive experimental and numerical study

During the thermal runaway process of lithium-ion batteries, the release of vaporized electrolyte and combustible gases can lead to the formation of a jet flame, posing a significant fire or explosion risk. In order to deal with the threat of lithium-ion battery vent gas fires to the safety of energy storage power stations, it's crucial to identify effective fire extinguishing agents for lithium-ion battery systems. This study employs a combination of experimental and numerical simulation methods to assess the suppression capabilities of CO2, N2, and HFC-227ea on vent gas/air premixed flames originating from lithium-ion batteries with various cathode materials. Laminar flame speed of vent gas/air/extinguishing agent premixed flames at specific equivalence ratios were measured using a Bunsen burner device under ambient temperature and atmospheric pressure conditions. Additionally, numerical calculations of laminar flame speed and adiabatic flame temperature were conducted using CHEMKIN-Pro, accompanied by an analysis of the chemical inhibition mechanism of HFC-227ea. The findings reveal that although HFC-227ea may slightly elevate the adiabatic flame temperature at lower equivalence ratios, its overall fire extinguishing efficacy surpasses that of CO2 and N2. These results offer valuable insights for selecting appropriate fire extinguishing agents for energy storage power stations, thereby enhancing the safety standards of energy storage systems.

Quantitative three-dimensional reconstruction of cellular flame area for spherical hydrogen-air flames

The cellular flame area continues to increase with the development of cells on the spherical flame surface, which will greatly promote the flame burning rate and propagation speed. This work mainly focuses on a new three-dimensional (3D) reconstruction method of the cellular structure on the flame surface, attempting to quantitatively characterize the real flame area. Initially, the visualization investigation of hydrogen-air premixed spherical flames within a constant volume vessel was conducted using the Schlieren optical technique under room temperature and atmospheric pressure conditions. In parallel, the Cellpose 2.0 graphical user interface was used for the preliminary training of the cell segmentation model. Subsequently, this pre-trained model was applied in the image post-processing, enabling the quantitative characteristics extraction of the cellular structure, such as the cells number, area, and the flame radius, etc. Additionally, a concept of peak height h on the flame profile was proposed to characterize the fluctuation degree of flame profile. A new flame equivalent radius ru was defined by the average value of valid distance from flame centroid to flame profile pixel by pixel. Based on the comparison of cell equivalent radius r and average peak height h¯, an innovative 3D reconstruction concept was proposed for the quantitative characterization of flame area. Finally, cellularity factor ξ was introduced to evaluate the cellularization degree on spherical flames surface. Results show that the appearance of secondary cracks marks the formal onset of flame cellularization, accompanied by an increase in the h¯. In the later stages of flame development, cellularization will eventually tend to a stable value of about 0.4, indicating the occurrence of “saturated state”. After 3D reconstruction, the average cell area stable at around 26 mm2 in this stage. The results of this study provide data support for the construction of combustion models in the field of premixed hydrogen-air combustion.

Analysis of Ozone and VOCs Pollution Characteristics, Sources, and Abatement Control Strategies in Hebi

In order to control the increasing ozone （O3） pollution in Hebi, Henan Province, clarifying the pollution characteristics of ozone and its precursors is vital. Therefore, we conducted a comprehensive analysis of O3 pollution utilizing the OFP-PMF-EKMA method combined with online hourly resolution monitoring data of conventional pollutants and volatile organic compounds （VOCs） in the summer of 2022 （June-September）. Ozone formation potential （OFP） was used to identify the key VOCs species, and the PMF model was used to identify the VOCs emission sources, whereas EKMA curves and scenario analysis were used to identify the main ozone control area in Hebi and to determine the reduction ratio of VOCs and NOx in a scientifically refined way. In 2022, Hebi had persistent O3 pollution, with the highest concentration in June. Conditions of high temperature, low humidity, and low atmospheric pressure contributed to the O3 accumulation. Aromatic and oxygenated volatile organic compounds （OVOCs） contributed significantly to the OFP and VOCs fraction, which were the dominant active substance and concentration dominant species. The results of the VOCs source analysis indicated that vehicle exhaust sources （25.3%） were the main source of atmospheric VOCs, followed by process sources （17.7%） and biomass combustion sources （17.6%）. Thus, emission sources associated with the combustion of fossil fuels and industrial production emissions were the most urgent sources of atmospheric VOCs to be controlled in Hebi. The O3 generation in Hebi occurred in the VOCs-sensitive zones, and the emission reduction results showed that a synergistic emission reduction of VOCs and nitrogen oxide （NOx） could effectively control O3 pollution with a 75% reduction in VOCs and a 10% reduction in NOx.

Solubility of codeine phosphate in ethylene glycol + N-methyl-2-pyrrolidone mixtures at different temperatures

ABSTRACT The primary objective of the present study is to systematically investigate the solubility data and thermodynamic properties associated with codeine phosphate within mixtures comprising ethylene glycol (EG) and N-methyl-2-pyrrolidone (NMP) under atmospheric pressure conditions within the temperature range of 293.2–313.2 K. The analysis reveals a discernible positive correlation with both temperature and the ratio of EG. Mathematical models are employed for the purpose of correlating the obtained data, and the reliability of these models is rigorously assessed through the computation of mean relative deviations for back-calculated values. Additionally, the density values of codeine phosphate saturated mixtures are meticulously measured and subsequently correlated utilising the Jouyban-Acree model. Furthermore, the apparent thermodynamic properties governing the solubilisation process of codeine phosphate, including standard enthalpy, entropy and Gibbs free energy, are computed through the application of Gibbs and van’t Hoff equations, and the obtained results are comprehensively documented.

Kinetic modeling of arabinoxylan extraction from Brewers’ spent grain using alkaline pretreatment at atmospheric pressure

This study evaluated the kinetic modeling of arabinoxylan (AX) extraction from Brewers’ spent grain (BSG) by alkaline pretreatment at atmospheric pressure, considering severe (low concentration of NaOH and high temperature) and moderate (high concentration of NaOH and low temperatures) process conditions. The effects of NaOH concentration and temperature on yield extraction were studied over time, as well as the concentration of weak acids and phenolic compounds at the end of the pre-treatment. The AX yield extraction varied from 41.2 % (1 M, 90 °C) to 64.8 % (4 M, 40 °C) after 1 h and 16 h, respectively. Acetic acid ranging from 420 ppm to 1020 ppm was released, while ferulic acid was the phenolic compound produced at the highest concentration ranging from 78.3 ppm to 224.1 ppm. In addition, rates of chemical reactions were correlated mathematically from the experimental data with a good fit, and a sensitivity analysis was performed to understand the kinetic behavior. The first-order kinetic model demonstrates that increasing AX extraction requires both low temperatures (between 30 and 40 °C) and low NaOH concentration, but at the same time, this effect increases the time required (16 h) to obtain the maximum AX yield (64.8 %).