High-pressure Rate Research Articles

Reaction between propionaldehyde and hydroxyperoxy radical in the atmosphere: A reaction route for the sink of propionaldehyde and the formation of formic acid

Understanding the chemical transformations of volatile organic compounds is particularly important for atmospheric modeling and elucidating their effects on atmospheric environment, where the key parameters are reaction mechanism and kinetics. Here, we report that the reaction mechanism and kinetics of propionaldehyde with hydroxyperoxy radical by using quantum chemical methods and reaction rate theory. In particular, we use our very recently developed dual-level strategy to obtain the high-pressure limit rate constants of the reaction of propionaldehyde (CH3CH2CHO) with hydroxyperoxy radical (HO2). We find that the enthalpy of activation at 0 K is only −1.86 kcal/mol in the CH3CH2CHO + HO2 reaction. The present results also uncover that the CH3CH2CHO + HO2 reaction depends on temperature and pressure and its high-pressure limit rate constant has negative temperature dependency with the value of 7.76 × 10−13 to 3.06 × 10−14 cm3 molecules−1 s −1 at 190–350 K. Moreover, the present findings also show that the reaction of propionaldehyde with hydroxyperoxy radical can make great contribution to the sink of propionaldehyde below 260 K and 1 atm when OH concentration is less than 8.4 × 104 molecules cm−3 at night and can not be ignored at 0–10 km altitude. We also find a potential route for the formation of formic acid by the reaction of propionaldehyde with hydroxyperoxy radical.

Effects of High Pressure-Assisted Extraction on Yield, Antioxidant, Antimicrobial, and Anti-diabetic Properties of Chlorogenic Acid and Caffeine Extracted from Green Coffee Beans

The bioactive ingredients of green coffee beans were extracted using high pressure-assisted extraction (HPE) and compared against those derived from the traditional heat reflux (HR) extraction method. The effect of extraction conditions on the extraction efficiency of functional components (chlorogenic acids, caffeine, total phenols, and flavonoids); the free radical-scavenging activity of the extract; and the inhibition of α-glucosidase, α-amylase, and food pathogenic bacteria were measured. Using water as the solvent, the high-pressure extraction rates of chlorogenic acid (CGA) and caffeine were 3.20–5.75 mg/100 g and 4.32–7.95 mg/100 g, respectively, which were significantly higher than the rates obtained using the traditional method (2.92 mg/100 g and 3.54 mg/100 g, respectively). Under optimal extraction conditions of 25 °C and 600 MPa for 2.5 min, inhibition of α-glucosidase and α-amylase by the extract reached rates of 27.8% and 26.7%, respectively, with the highest free radical-scavenging activity of 81.5%. HPE exhibited antibacterial activity against both gram-positive (Staphylococcus aureus and Listeria innocua) and gram-negative (Escherichia coli and Salmonella enterica) bacteria, and the lowest minimum inhibitory concentration (4.69 mg/mL) against S. aureus was achieved. Scanning electron microscopic observations evidenced that high pressure partially damaged the intercellular compartments of coffee beans, increased solvent permeability, and improved the extraction rate of bioactive ingredients. The outcomes of the study demonstrated that HPE can be employed as an efficient extraction technique for production of chlorogenic acids and caffeine that might have a potential application in food and related industries.

Dynamic response characteristics of adjacent tunnel lining under blasting impact in subway connecting passage

The connecting passage between two adjacent tunnels is conducive to the rescue and evacuation of subway tunnels when disasters occur. The blasting method is usually used in the construction of connecting passage. The vibration caused by blasting construction may endanger the safety of subway tunnel structure. As a result, the influence of blasting pressure on the stability of subway tunnel lining structure during the excavation of connecting passage is studied, and the safe blasting construction distance is proposed, which is crucial to the safety of adjacent subway tunnel lining. This study takes the connecting passage of Wuhan Metro Line 8 as an example. Using Finite element software ANSYS/LS-DYNA, an accurate numerical calculation model of construction site is established. The nonlinear elastoplastic mechanical characteristics of soil, rock, and tunnel lining are simulated by Drucker Prager, Plastic Kinematic, and Johnson Holmquist Concrete constitutive material models, respectively. The credibility of the three-dimensional numerical calculation model and material constitutive model was proved by contrasting the field measured data of the connecting passage with the numerical calculated results. Analysis of numerical results, the axial and radial PPV, frequency, and Von Mises stress of subway tunnel lining are obtained. The influence of subway tunnel lining under adjacent blasting can be obtained by analyzing the distribution law of PPV and Von Mises stress. Non-static tensile strength is needed considering the high pressure and high strain rate process of concrete during blasting. By fitting the relationship between PPV and dynamic tensile stress, and referring to DIF parameters, the safety range of PPV in subway tunnel lining blasting is determined. The critical safety distance between blasting construction and tunnel lining is obtained by Sadovsky vibration velocity attenuation formula, which is used to guide the subsequent blasting excavation of continuous tunnels.

Enhancing energetic performance of metal-organic complex-based metastable energetic nanocomposites by spray crystallization

Energetic metal-organic complexes have been involved in nanothermites as novel oxidants. However, the existing preparation methods often lead to mixing inhomogeneity and small contact area of ingredients, the reactivity and functionality of the novel energetic nanocomposites are still limited. In this work, spray crystallization (SC) method was used to prepare novel energetic nanocomposites, the high-energy metal-organic complex [Ni(CHZ)3](ClO4)2 (CHZ = 1,3-diaminourea) was composited with nano-aluminum (n-Al). Results showed that n-Al/[Ni(CHZ)3](ClO4)2 energetic nanocomposites prepared by SC method increased heat release to 2977.6 J/g and peak pressure to 3.91 MPa with higher pressurization rate (1324.06 MPa/s), decreased sensitivity thresholds (>100 mJ) to electrostatic discharge (ESD) and enhanced detonation ability compared with [Ni(CHZ)3](ClO4)2 alone and physically mixed (PM) n-Al/[Ni(CHZ)3](ClO4)2. These results proved that it is significant to introduce energetic metal-organic complexes with inherent high energy in new-concept n-Al/energetic metal-organic complexes nanocomposites through SC method for a better performance of its application.

Strong and osteoconductive poly(lactic acid) biocomposites by high-shear liquid dispersion of hydroxyapatite nanowhiskers

Controlled incorporation of bioactive hydroxyapatite (HA) into poly(lactic acid) (PLA) signifies a promising approach to design and development of biomedical-adaptive materials. Here we unravel a microwave-assisted biomineralization approach to synthesis of HA nanowhiskers (HANWs), which were characterized by well-controlled diameter (∼30 nm) and length (80 − 120 nm), combined with a desirable calcium − phosphorus ratio (Ca/P) of 1.67. A high-shear liquid dispersion (HSLD) method that provided a combination of high pressure (up to 50 kPa) and high shear rate approaching 10000 s −1 was established to fabricate homogeneous PLA/HANWs composites. In particular, upon incorporation of 30 wt % HANWs the tensile strength and elastic modulus of PLA-HA30 (76.7 MPa and 3.3 GPa) were elevated by 48% and 84% compared to those of pure PLA, respectively, as accompanied by a nearly 2-fold increase in the cell viability. This work paves a facile yet effective roadway to strong and osteoconductive PLA composites appealing for bone tissue repairing.

Combustion Performance and Low NOx Emissions of a Dimethyl Ether Compression-Ignition Engine at High Injection Pressure and High Exhaust Gas Recirculation Rate

Dimethyl ether (DME) is a promising alternative to diesel for compression-ignition (CI) engines used in various industrial applications. However, the high nitrogen oxide (NOx) emissions of DME combustion have restricted its use. The primary cause of high NOx emissions is a high combustion temperature. In this study, a high exhaust gas recirculation (EGR) rate was used when testing a common-rail direct injection CI engine suitable (with minor modifications) for a passenger car. A modified fuel supply system created high injection pressure during evaluation of combustion performance. The physical and chemical properties of DME were the principal determinants of the ignition delay, combustion speed, and heat release rate. Although a high injection pressure accelerated formation of the fuel-air mixture and the combustion speed, combustion performance deteriorated with increased NOx emissions. An increased EGR rate affected combustion and the NOx concentration. A high EGR rate effectively reduced NOx formation and emission under low-temperature combustion conditions. Also, the good DME combustion characteristics were maintained when the EGR rate was high, unlike for an ultra-low sulfur diesel engine.

Effects of Bisoprolol on Decreased Blood Pressure of Systole in Male White Rats Hypertension and Hypertension with Complications of Liver Dysfunction

Hypertension is a major public health problem and is known as an independent risk factor for cardiovascular disease. Patients with hypertension often experience complications such as liver dysfunction. Antihypertensive beta-blockers are often used by the public to treat high blood pressure and excessive heart rate. This study aimed to examine the effect of bisoprolol on decreasing systolic and diastolic blood pressure in hypertensive and hypertensive male white rats with complications of liver dysfunction. In this study, all-male white rats were made hypertensive by being induced with NaCl. Then, the group of animals complicated by liver dysfunction was induced with CCl4, then measured using a v5 + 5010 photometers. Meanwhile, the systolic blood pressures were measured using a CODA (kent scientific) instruments blood pressure gauge (Noninvasive blood pressure). The data from this study were analyzed by two-way ANOVA. It was found that the administration of bisoprolol at a dose of 2.5 mg, 5 mg, and 10 mg significantly decreased systolic blood pressure (p= 0.05). And the most effective dose is 10 mg in lowering systolic blood pressure in hypertensive and hypertensive male white rats with complications of liver dysfunction.

Hybrid Janus Membrane with Dual-Asymmetry Integration of Wettability and Conductivity for Ultra-Low-Volume Sweat Sensing.

Highly sensitive and selective analysis of sweat at ultra-low sample volume remains a major challenge in the field of biosensing. Manipulation of small volumes of liquid for efficient sampling is essential to address this challenge. A hybrid Janus membrane with dual-asymmetry integration of wettability and conductivity is developed for regulated micro-volume liquid transport in wearable sweat biosensing. Unlike the uncontrollable liquid diffusion in a conventional porous membrane, the asymmetric wettability of porous Janus membrane leads to unique unidirectional liquid transport with high breakthrough pressure (1737.66 Pa) and fast self-pumping rate (35.94 μL/min) for micro-volume liquid sampling. The asymmetric conductive layer shows excellent flexible conductivity, anti-interference of friction, and efficient electrochemical interface due to the in situ generation of gold nanoparticles on one side of the membrane. The fabricated Pt-enzyme electrodes on the membrane promises effective testing range, great selectivity, and high sensitivity and accuracy (correlation efficiency, glucose: R2 = 0.999, lactate: R2 = 0.997), enabling ultra-low volume (∼0.15 μL) real time measurements on the skin surface. The innovative Janus membrane with unidirectional, self-pumping, and anti-interference performance provides a new strategy for miniaturized wearable microfluidic sweat electrochemical biosensor preparation in athletic performance evaluation, health monitoring, disease diagnosis, intelligent medicine, and so forth.

Turbulent Flame Speed of a Gasoline surrogate in conditions representative of modern downsized Spark-Ignition engine

The downsized spark ignition (SI) engine is considered as one promising technology to reduce pollutants and greenhouse gas emissions. By boosting the intake air pressure, this operating mode achieves higher efficiency, thus reducing pollutant emissions. Modeling the combustion process in these drastic conditions (high pressure, high temperature and high dilution rate) remains challenging, however, since most of models of premixed turbulent combustion seem insufficiently robust because the turbulent combustion regime might be out of the classical flamelet regime. Two different setups, a spherical vessel and a one-shot engine, were used to study turbulence-flame interaction in conditions representative of a modern downsized SI engine, i.e. under high pressure, high temperature and high dilution and controlled turbulence. Turbulent flame speed were measured in a wide range of Damkohler and Karlovitz number. Several turbulent flame speed correlations from the literature are also tested and compared to the complete experimental dataset gathered on both setups.

Studying the strengthening mechanism and thickness effect of elastomer coating on the ballistic-resistance of the polyurea-coated steel plate

Experiments have shown that the ballistic performance of the steel plate improves significantly after coating polyurea at the impact face. However, the strengthening mechanism of the elastomer coating on the ballistic-resistance is not understood well until now. In this paper, the strengthening mechanism and thickness effect of the coating under fragment simulating projectiles (FSP) impact are studied through numerical and experimental analysis. Firstly, a viscoplastic constitutive model of polyurea is developed based on experimental characterization and thermodynamic equation of state. It can capture strongly nonlinear volumetric behavior and impact-induced shearing stiffening and strengthening considering the coupling of high pressure, high temperature, and high strain rate under ballistic impact. Then, by applying this newly developed viscoplastic model of polyurea, the underlying ballistic-resistant mechanism of the polyurea-coated steel plate is numerically studied. The analysis shows that the dynamic behavior of polyurea under ballistic impact and propagating regulation of impact wave jointly play the key role. One side, the impact-induced stiffening and strengthening of the polyurea change the failure modes of the steel plate and considerably improve the ballistic-resistance of the structure. The other side, increasing coating thickness can only provide the limited benefit for improving the ballistic-resistance of the structure, as obtained in experiments. For the impact-face-coated steel plate, the low-thickness polyurea coating suffering from FSP impact can increase the frequency of the compressive wave reflection-superposition on the high-impedance polyurea/steel interface before the energy transfer from the impacted location. This helps to improve the pressure level and enhance the instantaneous energy storage and dissipation of the polyurea per volume significantly. However, increasing coating thickness can make the pressure level and the specific energy density of polyurea decrease gradually during penetration. It is also found that the energy dissipation of FSP during penetration is reduced after increasing the coating thickness because of the erosion mitigation from the structure. The new insight on the strengthening mechanism of elastomer coating will be helpful for the light armor design.

NOx–Smoke Trade-off Characteristics in a Palm Oil-Fueled CRDI Diesel Engine under Various Injection Pressures and EGR Rates

Palm oil is one of the most common and productive vegetable oils, so it is often used as an excellent feedstock for biodiesel production. However, due to the high viscosity and other issues of palm oil, it cannot be directly used as an alternative fuel for diesel engines unless some treatment is carried out. In this study, the effects of palm oil-diesel blend fuel on the nitrogen oxides (NOx)–smoke trade-off characteristics were investigated in a common rail direct injection (CRDI) diesel engine under various injection pressures and exhaust gas recirculation (EGR) rates. It was found that NOx and smoke from the combustion of fuel containing 50% palm oil (P50D50) were simultaneously suppressed by 3% and 3.1% compared with diesel fuel at an injection pressure of 400 bar, respectively. The performance of P50D50 was comparable to that of diesel, but at high injection pressure and high EGR rate, it showed shorter ignition delay (ID) and lower smoke emission.

Performance of Waste Insulating Mineral Oil-Based Biodiesel in a Direct-Injection CI Engine

Mineral oil has been used as an insulating fluid in the power industry. However, surplus waste oil poses serious environmental threats because of disposal concerns. Waste to biofuel is an excellent way to deal with waste material from various sources. In this study, the trans-esterification method was utilised to convert the waste-insulating mineral oil into a quality bio-fuel. Waste-insulating transformer oil was converted to biodiesel, and it was tested according to ASTM standards. Four different blends of waste-insulating biodiesel with diesel in 25 per cent (WIOBD25), 50 per cent (WIOBD50), 75 per cent (WIOBD75), and 100 per cent fractions (WIOBD100), were used for performance testing in a direct injection compression ignition (DICI) engine. The combustion parameters such as BSFC, EGT, and BTE were evaluated with varying crank angles and constant engine speed. The waste-insulating biodiesel performance results are then compared with diesel fuel. BSFC increased as the biofuel mixture in diesel was raised, and the brake thermal efficiency (BTE) was significantly reduced compared to diesel for all WIOBD diesel mixtures. Due to the combustion process, a high pressure and heat release rate (HRR) were noticed inside the cylinder with the waste-insulating oil-derived biodiesel samples. WIOBD biodiesel blends produced lower levels of hydrocarbon, carbon monoxide, and smoke emissions than diesel fuel, but greater levels of nitrogen oxides (NOx) were produced than diesel fuel. In addition to lower emissions combined with improved engine performance, the WIOBD25 fuel blend has been found to be experimentally optimal for practical application. As a result, the test findings indicated that WIOBD biodiesel might be used as a substitute for conventional diesel fuel.

A review of internal combustion engines powered by renewable energy based on ethanol fuel and HCCI technology

<abstract> <p>In general, as compared to conventional combustion engines, the homogeneous charge compression ignition (HCCI) engine offers better fuel efficiency, NOx, and particulate matter emissions. The HCCI engine, on the other hand, is not connected to the spark plugs or the fuel injection system. This implies that the auto-ignition time and following combustion phase of the HCCI engine are not controlled directly. The HCCI engine will be confined to a short working range due to the cold start, high-pressure rate, combustion noise, and even knocking combustion. Biofuel innovation, such as ethanol-powered HCCI engines, has a lot of promise in today's car industry. As a result, efforts must be made to improve the distinctive characteristics of the engine by turning the engine settings to different ethanol mixtures. This study examines the aspects of ethanol-fueled HCCI engines utilizing homogenous charge preparation procedures. In addition, comparing HCCI engines to other advanced combustion engines revealed their increased importance and prospective consequences. Furthermore, the challenges of transitioning from conventional to HCCI engines are examined, along with potential answers for future upgrade approaches and control tactics.</p> </abstract>

A review of internal combustion engines powered by renewable energy based on ethanol fuel and HCCI technology

<abstract> <p>In general, as compared to conventional combustion engines, the homogeneous charge compression ignition (HCCI) engine offers better fuel efficiency, NOx, and particulate matter emissions. The HCCI engine, on the other hand, is not connected to the spark plugs or the fuel injection system. This implies that the auto-ignition time and following combustion phase of the HCCI engine are not controlled directly. The HCCI engine will be confined to a short working range due to the cold start, high-pressure rate, combustion noise, and even knocking combustion. Biofuel innovation, such as ethanol-powered HCCI engines, has a lot of promise in today's car industry. As a result, efforts must be made to improve the distinctive characteristics of the engine by turning the engine settings to different ethanol mixtures. This study examines the aspects of ethanol-fueled HCCI engines utilizing homogenous charge preparation procedures. In addition, comparing HCCI engines to other advanced combustion engines revealed their increased importance and prospective consequences. Furthermore, the challenges of transitioning from conventional to HCCI engines are examined, along with potential answers for future upgrade approaches and control tactics.</p> </abstract>

Transition of elastomers from a rubber to glassy state under laser shock conditions.

The mechanical behaviour of polycarbonate and polydimethylsiloxane (Sylgard184) is studied in this work under laser shock conditions that induce high pressure and strain rates. Laser shock, usually used to reinforce metals, is chosen here because of its capacity to produce strain rates in the 106 s1 range and pressures of GPa order. The pressure and strain rates produced are extracted from the backface velocity profiles and reproduced with the FEM simulation on Abaqus for each laser shot. These two parameters lead to a glass transition shift in the polymers that can induce significant behaviour modifications. We show that Sylgard184, an elastomer with a glass transition temperature of 147 K, exhibits glassy behaviour under such laser shock conditions. By contrast, polycarbonate is already a glassy polymer in its normal state with a glass transition temperature of 415 K; no drastic change in behaviour under shock is evidenced. To discuss these findings in relation to the different mobility domains of the polymer chains under extreme conditions, dielectric relaxation spectroscopy (DRS) measurements are performed to characterize the limits of the rubbery and glassy behaviour for both polymers. As a result, the coupling of the two techniques provides a deeper understanding of the contribution of both the strain rate and pressure to the dynamic glass transition in polymers and thus expands the experimental study range of the two polymers to a strain rate that had not previously been reached.

Grading of Japanese Diet Intakes by 24-Hour Urine Analysis of Taurine and Soy Isoflavones in Relation to Cardiovascular Risks.

To investigate the association of the Japanese diet with risks for lifestyle-related diseases, the biomarkers of seafood and soybean consumption, taurine (T) and soy isoflavones (I), and others were analyzed in 24-hour urine (24U) samples collected from participants of the Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study coordinated by the World Health Organization (WHO). The data of T and I normalized for creatinine content in 24U were divided into five quintiles, T1 to T5, and I1 to I5. The total data of the collected samples were divided into 25 groups, which were obtained by 5 (T1-T5)×5 (I1-I5) according to 24U excretions of T and I corresponding to the intake of seafood and soybeans from the least to the highest, respectively. Since these two nutrients were often consumed together in the Japanese diet, this characteristic was expressed as J1 to J5 based on the amounts of 24UT and I excretions. The risks for lifestyle-related diseases, obesity (body mass index, BMI), and cholesterolemia became lower during the transition from J1 to J5, while HDL cholesterol levels became higher from J1 to J5. On the contrary, urinary salt excretion and the sodium (Na)/potassium (K) ratio became higher from J1 to J5. Systolic blood measure was significantly lower in J3 than in J5. Diastolic blood pressure was also significantly lower in J3 than in J1. In conclusion, the higher the J score, which corresponds to Japanese dietary habits, the lower the BMI and cholesterol levels, as well as mortality rate from coronary heart disease, but the higher the average life expectancy among the Japanese. However, these higher J scorings were associated with high-salt intake and high Na/K ratios; therefore, they contributed to high blood pressure and high mortality rate caused by stroke in Japan. These results indicate that low-salt intake should be recommended to the Japanese who are consuming seafood and soy regularly in order to maintain lower blood pressure and to extend healthy life expectancy with a lower risk of stroke. Moreover, high scorings of the Japanese diet correspond to the high intake of magnesium (Mg) which is rich in seafood including seaweeds and soy. Therefore, low-salt seafood and soy intake is expected to reduce the incidence of the metabolic syndrome, the risk of which is inversely related to T and Mg intake.

The merit of pressure dependent kinetic modelling in steam cracking.

Renewable cracking feedstocks from plastic waste and the need for novel reactor designs related to electrification of steam crackers drives the development of accurate and fundamental kinetic models for this process, despite its large scale implementation for more than half a century. Pressure dependent kinetics have mostly been omitted in fundamental steam cracking models, while they are crucial in combustion models. Therefore, we have assessed the importance of pressure dependent kinetics for steam cracking via in-depth modelling and experimental studies. In particular we have studied the influence of considering fall-off on the product yields for ethane and propane steam cracking. A high-pressure limit fundamental kinetic model is generated, based on quantum chemical data and group additive values, and supplemented with literature values for pressure dependent kinetic parameters for β-scission reactions and homolytic bond scissions of C2 and C3 species. Model simulations with high-pressure limit rate coefficients and pressure dependent kinetics are compared to new experimental measurements. Steam cracking experiments for pure ethane and propane feeds are performed on a tubular bench-scale reactor at 0.17 MPa and temperatures ranging from 1058 to 1178 K. All important product species are identified using a comprehensive GC × GC-FID/q-MS. For homolytic bond scissions, the inclusion of pressure dependent kinetics has a significant effect on the conversion profile for ethane steam cracking. On the other hand, pressure dependence of C2 β-scissions significantly influences conversion and product species profiles for both ethane and propane steam cracking. The C3 β-scissions pressure dependence has a negligible effect in ethane steam cracking, while for propane steam cracking the effect is non-negligible on the product species profiles.

Tuning High and Low Temperature Foaming Behavior of Linear and Long-Chain Branched Polypropylene via Partial and Complete Melting.

While existing foam studies have identified processing parameters, such as high-pressure drop rate, and engineering measures, such as high melt strength, as key factors for improving foamability, there is a conspicuous absence of studies that directly relate foamability to material properties obtained from fundamental characterization. To bridge this gap, this work presents batch foaming studies on one linear and two long-chain branched polypropylene (PP) resins to investigate how foamability is affected by partial melting (Method 1) and complete melting followed by undercooling (Method 2). At temperatures above the melting point, similar expansion was obtained using both foaming procedures within each resin, while the PP with the highest strain hardening ratio (13) exhibited the highest expansion ratio (45 ± 3). At low temperatures, the foamability of all resins was dramatically improved using Method 2 compared to Method 1, due to access to lower foaming temperatures (<150 °C) near the crystallization onset. Furthermore, Method 2 resulted in a more uniform cellular structure over a wider temperature range (120–170 °C compared to 155–175 °C). Overall, strong extensional hardening and low onset of crystallization were shown to give rise to foamability at high and low temperatures, respectively, suggesting that both characteristics can be appropriately used to tune the foamability of PP in industrial foaming applications.

Effect of Heat Treatment Process and Composition on Deformation and Damage Behavior of WHA under Detonation Loading

The excellent material properties of tungsten heavy alloy (WHA) make it widely used in the military field. When used as killing elements of weapons, its dynamic mechanical properties under detonation loading directly determine the damage effect of weapons, which makes the research on its mechanical behaviors under high pressure and high strain rate loads such as detonation loading of great significance. In this paper, several WHAs with different compositions and processes are selected, and the mechanical properties and deformation and damage behavior under static explosion test are analyzed by combining macro and micro study, so as to provide guidance for the subsequent optimization of the performance design of WHA.

Experimental study on liquid oxygen chill-down in a horizontal exit-contracted pipe

Liquid oxygen chill-down in a horizontal exit-contracted pipe was investigated experimentally. The outer wall temperatures were recorded in the detailed manner. Results show the temperatures in the center length of the pipe decrease first, which shows much different manners from those in the transport pipe. This indicates that liquid accumulates in the center length to form quenching head, which propagates to the both sides of the pipe during the liquid oxygen chill-down process in the exit-contracted pipe. Based on the present set of data, the correlations on temperature of Leidenfrost point was corrected, and critical heat flux was well correlated by new expression from bubble separation theories. Results show that, for high pressure or high flow rate cases, Leidenfrost point is controlled by the increase of instable wave on the liquid propagation area. However, for other cases, Leidenfrost point is controlled by heat transfer.