Air Injection Research Articles

Introducing soil air injection device to reduce carbon footprint of rice production system in China

Improving soil aeration in paddy fields using mechanical device reduces methane (CH4) emissions, whereas it also increases the contribution of other sources (device production, agricultural inputs, etc.). Here, this study applied the life cycle assessment (LCA) method to evaluate the carbon footprint of a soil air injection device (SAID) in rice field. We further analyzed the prospects of this device in promoting carbon emission reduction in China's main rice-producing areas, which was combined with economic benefit calculation and revised knowledge-attitude-practice (KAP) model. Results showed that the reduction of net carbon emissions from paddy fields under SAID treatment was 4.51–241.95% higher than the total carbon emissions from the production, transportation, operation, and recycling of SAID. The economic output of using SAID in rice fields could just offset the cost of it. With reasonable government subsidies (142.80–349.95 yuan SAID−1 yr−1), SAID can reduce carbon emissions from Chinese rice fields by ∼ 41.60 Tg CO2-eq yr−1. This study suggests that using SAID in some rice planting areas in China may be an effective way to reduce carbon emissions.

Анализ систем обеспечения безопасности стендовых испытаний энергоустановок на основе топливных элементов, применяемых на автомобильном транспорте

A theoretical analysis is given related to the ways to reduce the negative impact of motor vehicle exhaust gases on the environment. The possibility of using hydrogen as an energy source for an electric power plant used in the road transport is considered. The operation of a high-power fuel cell battery is advisable on both passenger cars and trucks. However, such technologically complex systems require additional tests at the development stage for verifying the fire safety and tightness of the structure. The systems of storage, transportation, preparation of hydrogen and safety assurance during the performance of such bench tests are analyzed. Fuel cell stack test benches must be provided with additional protection against occurrence of fires and explosions. It is based on a gas-analytical fiber-optic resonant (vibration frequency) sensor that monitors the accumulation of explosive gases. The key parameters of this system are the inertness and speed of the individual elements. A block diagram of a test bench for a fuel cell stack with a power of 150 kW is presented, the hydrogen pressure is reduced to 2–2.5 atm. During the operation of the installation, it is required to ensure continuous monitoring of the pressure in the system and in its individual parts, as well as to monitor the temperature regime of the gas supply in the fuel cell itself. The description of the principle of the test stand functioning is given. Its technological modules are identified, such as a hydrogen supply system, a cooling system, an air injection system, a power plant, and a block for simulating a potential load on an electric motor of the vehicle.

Compressed air energy storage (CAES): current status, geomechanical aspects and future opportunities

Abstract A compressed air energy storage (CAES) facility provides value by supporting the reliability of the energy grid through its ability to repeatedly store and dispatch energy on demand. Two main advantages of CAES are its ability to provide grid-scale energy storage and its utilization of compressed air, which yields a low environmental burden, being neither toxic nor flammable. The focus of this review paper is to deliver a general overview of current CAES technology (diabatic, adiabatic and isothermal CAES), storage requirements, site selection and design constraints. We discuss underground storage options suitable for CAES, including submerged bladders, underground mines, salt caverns, porous aquifers, depleted reservoirs, cased wellbores and surface pressure vessels. A geomechanical perspective is provided regarding the pressure limits for these options. The impacts of cyclic injection and withdrawal of compressed air, and the importance of caprock assessments with porous rock CAES, are also discussed. In addition, we provide an overview of the large-scale CAES facilities that are currently active or under development and a cost comparison of the diabatic, adiabatic and isothermal CAES options. Lastly, we outline major challenges and future opportunities for CAES and the top priorities for research, industry and stakeholders.

Effects of Injection Sequences on Spray Characteristics of an Air-Assisted Atomizer for Two-Stroke Aviation Engines

AbstractThe air-assisted atomizer used in a two-stroke aviation engine has two separate operation sequences, namely the fuel injection and air injection, in contrast to the synchronous fuel/air injection of conventional effervescent atomizers for continuous combustion engines. This work presents a numerical flow modeling to explore the effects of these two injection sequences on the effervescent spray formation, using the combined methodology of Eulerian–Eulerian multiphase technique and Shear-Stress Transport k–ω turbulence model. The transient fuel delivery in the internal fuel passage of the atomizer and the effects of the injection sequences on the developments of the droplet sprays were studied. Three characteristic times T1, T2, and T3 were introduced to specify the fuel injection duration, air injection duration, and the time interval between these two injection sequences, respectively. The results showed that the most important role of T1 is to meter fuel mass loading, and T2 plays the dominant role in anchor-shaped spray structure. For the air-injection sequence, there is a critical time, T3c, which is defined as the minimum opening time of the air injector, for the complete ejection of the fuel in the atomizer, which shows a linear correlation to T2, but is weakly related to T1.

Numerical Simulation of the Fin Impact on the Cooling of the Shell of a Rotary Kiln

This work consists of a numerical study of a thermally stressed rotary kiln shell part in a cement plant. The numerical simulations are performed by using the finite volume method for the discretization and the simple algorithm for resolution. The velocity air injection, its temperature, and the kiln rotational velocity are the main parameters under investigation. The distribution of temperature, velocity, and pressure, as well as the evolution of the Nusselt number are determined. In the second step of this study, fins are inserted on the shell to examine their effect on cooling. The results analysis shows that the insertion of fins to the shell has a significant influence on the decrease in temperature of the shell’s external surface. The study shows that this decrease in temperature depends significantly on the air injection rate, not on its temperature, and a bit less on the rotating velocity of the kiln. To avoid overloading our equipment (weight of the shell), only four fins distributed around the kiln are added to explore their effect.

Study on the Effect of Air Injection Location on the Drag Reduction in SWATH with Air Lubrication

In this paper, the air lubrication method is applied to high-speed SWATH (small waterplane area twin hull) to reduce the resistance. The influence of air injection locations on drag reduction is investigated. The computed results are compared with experimental results, and the grid independence test is performed. Then, the numerical method is used to simulate the resistance of SWATH in calm water with airflow. The hull is divided into different areas, and the influence of the air injection location on the drag reduction in different areas of the hull is studied through different air injection locations and airflow rates. It could be seen that the air injection location on the underwater body is more conducive to the drag reduction in SWATH than the air injection location on the strut. Besides, the air injection location near the bow of the underwater body could cause a better drag reduction effect of SWATH. There are obvious differences in the drag reduction effect of different areas of the underwater body.

Influence of operating conditions on flow field dynamics and soot formation in an aero-engine model combustor

Large-eddy simulations of a sooting aero-engine model combustor are performed for three operating points. They are analyzed to investigate the influence of secondary air injection and primary equivalence ratio on soot formation dynamics. It will be shown how the causes of a strongly intermittent sooting behavior can be investigated quantitatively by mode analysis and correlated statistics. Simulations rely on Arrhenius reaction rate-based finite-rate chemistry, where 79 species transport equations are solved simultaneously to accurately predict the combustion of ethylene: 43 species represent the gas phase, 36 the soot and soot precursors. Soot evolution is described by a well validated sectional soot model including a sectional model for polycyclic aromatic hydrocarbons and their radicals. This approach captures the influence of changing operating conditions on soot formation well. Hence, soot prediction is found to be accurate enough to investigate the formation processes. The presence of coherent and incoherent flow field dynamics in the combustor necessitates the use of multiresolution proper orthogonal decomposition and correlated statistics for the analysis. While the precessing vortex core is found to support soot production continuously, low frequency dynamics are identified to cause the intermittence at all operating conditions. Secondary air injection significantly increases the intensity of the low frequency dynamics. Yet, the soot volume in the combustor varies by the same order of magnitude without secondary air injection. The soot formation intermittence is closely linked to an axially symmetric mixture fraction mode near the primary injector at all operating conditions. Low mode energy required an additional mode analysis of joint statistics which confirmed this conclusion. Increasing the equivalence ratio at the primary injector decreases the influence of the low frequency dynamics on soot formation.

Large-scale micro-aerobic digestion studies at municipal water resource recovery facilities for process-integrated biogas desulfurization

Biogas generated from anaerobic digestion processes typically requires gas conditioning including hydrogen sulfide removal before it is used on-site to generate electricity and heat or before upgrading to biomethane for gas pipeline distribution or vehicle fuel. Experiments of process-integrated micro-aeration in three different large-scale sludge digesters (effective volume 2450 m3, 3250 m3 and 3300 m3) were undertaken at municipal wastewater treatment plants and compared with large-scale applications reported in literature. This work discusses critical process parameters, advantages, and potential limitations of micro-aerobic digestion in comparison with other commonly used biogas desulfurization methods. It shows that high H2S reduction in the biogas can be obtained and that the H2S reduction is dependent not only on the air injection rate and location, but also on the digestion activity identified by the volumetric biogas production. Reliability testing of typical micro-aerobic upset scenarios and long-term micro-aerobic digester operation as part of this study provided deeper insights in the MA process that could also provide valuable input to what operational, maintenance and safety measures should be considered when applying micro-aeration in large-scale digesters. The large-scale micro-aerobic digestion trials demonstrated that the hydrogen sulfide concentration in the biogas can be controlled using minimal plant upgrades, contributing to the sustainability and economic efficiency of the energy recovery process of waste sludge digestion at water resource recovery facilities.

Real-Time Behaviour of Dredged Slurry Treated by Air-Booster Vacuum Consolidation

The air-booster vacuum preloading method has been applied to slurry ground improvement. It is based on the conventional vacuum preloading method but with an additional injection of pressurised air into the soil via pre-installed conductors. The drainage effect of air-booster vacuum preloading has been demonstrated by past studies; however, direct observations of the real-time behaviour of slurries subjected to boosted air remain lacking. This study used a combined monitoring technique that included particle image velocimetry, pore water/air pressure gauges, a vortex flowmeter and an electronic balance to conduct a laboratory test of air-booster vacuum consolidation of dredged slurry. The tests allowed analyses of (1) the real-time displacement field of the slurry, (2) the pressure–flux relationship of the pressurised air, and (3) the pore water pressure responses during air boosting. The first aspect allowed direct observation of small-crack initialisation and propagation during pressurisation; while the latter two confirmed the crack initiation based on drops in air and pore water pressures. The measured crack initiation pressure was verified by comparison with theoretical predictions. The results demonstrate that pressurised air induces cracks in soil, which promote the drainage consolidation of dredged slurry.

In-situ combustion technique for developing fractured low permeable oil shale: Experimental evidence for synthetic oil generation and successful propagation of combustion front

The idea of in-situ combustion (ISC) for oil shale development and conversion has been proposed recently. Due to the low permeability of oil shale, it usually requires fracturing operation before air injection. However, one of the biggest technical questions is, whether the combustion front can be established and steadily propagate in the low permeable oil shale with fractures. To date, no experimental work has been reported to support this. The target of this work is to provide experimental evidence to answer this question. We have managed to create a novel method for packing and fracturing oil shale core samples in a combustion tube for simulating ISC processes. A systematic analysis for the physical–chemical modeling of ISC process in combustion tube was performed, including temperature profile, pressure drop buildup, composition of produced gases, X-ray computed tomography (CT) and visual inspection, as well as total organic content analysis of oil shale samples before and after combustion, calculation of combustion parameters (air requirement, air/fuel ratio, apparent atomic H/C ratio, oxygen utilization, and O2/fuel ratio), and synthetic oil production. All results indicated the successful establishment and propagation of the combustion front in the fractured, low-permeability oil shale sample. In addition, the permeability of oil shale was increased 2–3 times during combustion, which can be an important factor that supports the stable propagation of the combustion front. Furthermore, the effect of water and catalysts on ISC performance was investigated. It was found that water promotes the cracking reactions of heavy oils to produce CO2 and hydrocarbon gases, and the co-existence of catalysts and water together further improved the performance of the ISC process and synthetic oil production. The findings in this work provide the experimental evidence of the successful establishment and propagation of combustion front in fractured, low-permeability oil shale, and technically proves the feasibility of using ISC technology for in-situ retorting of oil shale to generate synthetic oil for the development and conversion of low permeable oil shale with additional fracturing.

A novel equation for the air injection and oil production during fire-flooding process based on experimental study in developing heavy oil reservoir

Fire flooding (FF) has been one of the important thermal enhanced-oil-recovery technologies in developing heavy oil reservoir. Many scholars have carried out laboratory studies on the complex oil-displacement mechanism due to the complex physical and chemical reactions for fire flooding. However, almost no one had given an equation expression of gas injection and production during fire-flooding process. Therefore, the FF and flue gas flooding (FGF) experiments of one-dimensional combustion tubes were conducted. The oil-recovery differences of FF and FGF experiments under the same conditions were calculated, and a high linear correlation was found. The results showed that the FF effects were mainly affected by the flue-gas when the gas injection was low, and the combustion-front expansion (CFE) effects made the main contribution when the gas injection was high. The gas injection, water and liquid production were logarithmically treated and compared with the oil production. It was found a strong linear relationship between the two sets of experiments, and the linear relationship was stronger in the FGF experiment. Among all the linear relationships, the logarithm of water production and oil production had the strongest linear relationship. Based on this understanding, the water and oil production were connected from flue gas in FF process, and a novel FF equation was derived and obtained. Finally, the production curves on site of the two typical FF cases and the fitting curves of the FF equation were descripted and compared. The results showed that the novel equation can reflect and forecast the field performance by FF process in developing heavy oil reservoir.

Repulsion driven by groundwater level difference around cutoff walls on seawater intrusion in unconfined aquifers

Cutoff walls have been widely used to prevent seawater intrusion (SWI) in coastal regions. Previous studies generally concluded that the ability of cutoff walls to prevent seawater intrusion depends on the higher flow velocity at the wall opening, which we have shown is not the most critical mechanism. In this work, we implemented numerical simulations to explore the driving force of cutoff walls on the repulsion of SWI in both homogeneous and stratified unconfined aquifers. The results delineated that the inland groundwater level was raised by cutoff walls, which generated a significant groundwater level difference beside two sides of the wall and thus provided a large hydraulic gradient to repel SWI. We further concluded that by increasing inland freshwater influx, the construction of cutoff wall could result in a high inland freshwater hydraulic head and fast freshwater velocity. The high inland freshwater hydraulic head posed a large hydraulic pressure to push the saltwater wedge seawards. Meanwhile, the fast freshwater flow could rapidly carry the salt from the mixing zone to the ocean and induce a narrow mixing zone. This conclusion explained the reason that the cutoff wall can improve the efficiency of SWI prevention through recharging freshwater upstream. With a defined freshwater influx, the mixing zone width and saltwater pollution area mitigated with the increase of the ratio between high and low hydraulic conductivity values (KH/KL) of the two layers. This was because the increase of KH/KL caused a higher freshwater hydraulic head, a faster freshwater velocity in the high-permeability layer, and the prominent change of flow direction at the interface between the two layers. According to the above findings, we deduced that any way to increase the inland hydraulic head upstream of the wall would improve the efficiency of cutoff walls, such as the freshwater recharge, the air injection, and the subsurface dam.

Machine learning clustering algorithms for the automatic generation of chemical reactor networks from CFD simulations

Predicting the thermal and environmental performances of combustion systems can be difficult and computationally expensive. Chemical Reactor Networks (CRN) represent an appealing solution for performing faster numerical simulations since they can carry out calculations with detailed kinetics in a significantly reduced amount of time. However, the design of such models is challenging, as it usually requires a considerable amount of expertise from the user. In this work, we present a novel, automatic methodology for the design of CRN models, which consists of the post-processing of CFD data via a combination of unsupervised clustering and graph scanning algorithms. The methodology was tested on a semi-industrial furnace which can operate in Moderate or Intense Low oxygen Dilution (MILD) combustion. The furnace operates at a nominal power input of 15 kW and is fed with several CH4-H2 mixtures, with two different air injector diameters. First, RANS simulations of the different cases were performed and validated against experimental data. Subsequently, different CRNs were extracted singularly for each case and simulated using detailed kinetics mechanisms. The different CRNs showed good performances in predicting NO emissions for the entire range of cases, as the results were in reasonable agreement with experimental data. Last, the capability of a single CRN to extrapolate towards different operating conditions was also assessed by using one single CRN for the simulation of different fuel mixtures. The approach showed a good level of generalization since the NO predictions were close to the experimental values.

Growing Corn and Sugar Beets with Feedlot Effluent, Air Injection, and Subsurface Drip Irrigation System in Western Nebraska

As a state with the most irrigated agricultural land in the United States, Nebraska relies on freshwater resources for its irrigation. In addition to these conventional water sources, using nonconventional alternatives for crop production can be important during water shortage times. In this research, effluent from a feedlot lagoon was used as an irrigation water source at a subsurface drip irrigation (SDI) system for corn (C) and sugar beet (SB) production in western Nebraska during the 2019 and 2021 growing seasons. The objective of this study was to evaluate the effect of air injection on C and SB yield when using feedlot runoff as an irrigation source in a SDI system. Results indicated that air injection treatment (O), compared to noninjection treatment (NO), increased corn yield by 5.50% in the 2019 growing season, yet differences were not significant. During the 2021 growing season, O significantly increased corn yield by 9.17% (p = 0.04). Differences in irrigation water productivity (IWP) of NO (14.19±1.90 kg ha−1 mm−1) and O (14.86±1.79 kg ha−1 mm−1) were not significant during the 2019 growing season while significant differences in IWP of NO (22.61±5.88 kg ha−1 mm−1) and O (24.68±4.55 kg ha−1 mm−1) were observed during the 2021 growing season (p = 0.004). In sugar beets, no significant difference was observed in crop yield or sucrose yield between O and NO during both growing seasons. Differences in IWP were not significant during the 2019 growing season (NO: 0.10±0.02 kg ha−1 mm−1, O: 0.10±0.03 kg ha−1 mm−1) and 2021 growing season (NO: 0.10±0.04 kg ha−1 mm−1, O: 0.09 ±0.02 kg ha−1 mm−1).

Numerical investigation of novel geometric solutions for erosion problem of standard elbows in gas-solid flow using CFD-DEM

As erosion by solid particles is a serious concern in the pipeline industry, especially in pneumatic transport pipelines, this study has investigated novel numerical geometric solutions to solve this problem using the computational fluid dynamics (CFD). The studied geometries included square section elbow (with a replaceable backing plate), T-plug, double T-plug, T-plug with axillary air and standard elbow with vane, ribbed-elbow (circular and square section) with different configurations, and elbow with air injection with different conditions. Results of the sensitivity analyses used to study the effects of the changes in the particle shape/size/velocity, mass loading, erosion model and turbulence model on erosion rate revealed that long-radius ribbed-elbow (circular and square section, θ = 30°), long-radius elbow with vane, long-radius elbow with square section, double T-plug and elbow with air injection (with Vinjection = 0.6Vmain and tilt angle = 45°) are good choices.

Characteristics of Maize Roots under Subsurface Drip Irrigation through Various Oxygen Treatment

In Korea, irrigation technology using subsurface drip irrigation (SDI) is new in agriculture system. Many limitations of SDI are not well known. SDI can damage crops from overwatering. To address this weakness, it is important to improve and test the applicability of the SDI with air injection (oxygation). Therefore we investigated soil oxygen (O2) and carbon dioxide (CO2), root characteristics and yield of maize using two conditions of soil moisture regime: field capacity (FC) × 100% and 120%. Maize was planted, and then air was injected by compressor and venturi. In the field, irrigation was controlled by a controller connected to soil moisture sensors. Soil moisture sensors were measured at 20 cm below soil surface. Soil O2 and CO2 were measured at 10 and 30 cm below soil surface before and after oxygation. Root activity was measured from tip of roots. Root volume and dry weight were measured. Post-harvest, number and weight of maize ears were surveyed as well. As a result, soil oxygen values increased by 59% in the compressor treatment and by 34% in the venture treatment. However, soil CO2values did not depend on the oxygation. In all soil moisture treatments, the activity of oxygated roots was greater than that of the control, and root activity was increased by 152%. Root volume and dry weight were also greater than those in the control. No significant effect of soil moisture was found on the number and weight of ears of maize. The average ear weight of maize in the FC 100% soil moisture treatment was 1,292 kg 10a-1 in the oxygation and 1,278 kg 10a-1 in the control. In addition, no effect of oxygation was observed on number and weight of ears. The average ear weight of maize in the FC 120% soil moisture treatment was 1,229 kg 10a-1 in the oxygation and 960 kg 10a-1 in the control. Maize yield was 28% greater in the oxygation treatment than that in the control. The yield of maize grown in the control field showed a tendency to decrease as the soil moisture content increased. At FC 120% soil moisture, the ear weight of control maize was reduced by 25% compared to FC 100% soil moisture. These results reflected that the oxygation process had a great effect on the root growth even in humid conditions, which was expected to have a positive effect on the maize plants planted above-ground.Root activity, dry weight and volume of corn as a result of soil moisture and oxygation; Soil moisture treatments (field capacity × 100%, field capacity × 120%), Oxygation treatments (compressor, venturi), Control (no air was injected). Soil moisture regime Oxygation treatment Root activity (µg g-1 h-1) Root dry weight (g) Root volume (cm3) 100% of field capacity Compressor 50.1 ± 1.69 b† 49.5 ± 19.25 a 269 ± 83.8 a Venturi 67.8 ± 3.25 a 44.6 ± 10.17 a 224 ± 34.9 a Control 32.2 ± 2.08 c 12.5 ± 5.55 b 59 ± 43.8 b 120% of field capacity Compressor 50.8 ± 1.07 a 42.4 ± 0.74 ab 225 ± 5.0 b Venturi 39.2 ± 1.54 b 73.7 ± 25.75 a 326 ± 56.6 a Control 35.8 ± 1.52 c 14.6 ± 9.81 b 60 ± 48.2 c †a, b and c represent significant difference level at 95%.

Carbon Dioxide Pyelography: A Convenient and Safe Alternative to Both Room Air and Iodinated Contrast Pyelography During Endourologic Procedures.

Introduction/Background: There are increasing reports of serious complications related to the air pyelography technique, which raise concerns about the safety of room air (RA) injection into the renal collecting system. Carbon dioxide (CO2) is much more soluble in blood than nitrogen and oxygen and thus considerably less likely to cause gas emboli. Iodinated contrast medium (ICM) is expensive, and supplies may not be as reliable as previously assumed. CO2 pyelography (CO2-P) techniques using standard fluoroscopy and digital subtraction fluoroscopy (CO2 digital subtraction pyelography [CO2-DSP]) are described. Materials and Methods: During the endourologic stone cases, 15 to 20 mL of CO2 gas was typically injected into the renal pelvis through a catheter or sheath. Imaging was usually obtained with endovascular CO2 digital subtraction angiography settings using either a traditional fluoroscopy system (TFS) or robotic arm multiplanar fluoroscopy system (RMPFS) (Artis Zeego Care+Clear®; Siemens). Results: CO2-P was performed in 22 endoscopic stone treatment cases between March 2021 and August 2022, primarily using digital subtraction settings in 20 cases. CO2-DSP overall provided higher quality images of the renal pelvis and collecting system than CO2-P, but with a relatively higher radiation dose. Following a quality intervention, fluoroscopy doses for CO2-DSP cases were decreased by 81% overall. The use of CO2-P avoided fluoroscopic or intraoperative CT (ICT) artifacts seen with intraluminal ICM. Conclusions: CO2-P allows the urologist to obtain imaging of the renal collecting system without ICM and with much lower risk of air embolism compared with RA pyelography. CO2 is a nearly cost-free alternative to ICM. Because CO2 is widely available and the technique is easy to perform, we propose that CO2-P should be favored over traditional air pyelography to improve patient safety.

In Situ Combustion of Heavy Oil within a Vuggy Carbonate Reservoir: Part I—Feasibility Study

Worldwide, the known recoverable heavy oil and bitumen reserves make up more than 64% of the total reserves, of which more than 60% are trapped in carbonates. Air injection has immense potential for hydrocarbon recovery from various reservoirs. While most of the successful air-based techniques are performed within carbonate reservoirs containing light oil, theoretically, in situ combustion (ISC) has also shown great potential for recovering heavy oil and bitumen. Carbonates are complex in terms of geology and are often associated with fractures and vugs that affect the fluid flow, pressure propagation and progression of the ISC reactions. This paper describes the first experiment in which the triple-porosity concept was applied to simulate heterogeneity through artificially induced vugs, core matrix and fractures. This approach was used to study the feasibility of the ISC recovery technique for heavy oil (14° API) within a dolomite reservoir using a combustion tube (CT) in an experiment performed at 1740 psig. The combustion front advanced through 78% of the core length prior to the termination of air injection, producing 80% of the initial oil. To differentiate between the various sources of the CO2 gas (a product of carbonate decomposition vs. the combustion reaction) the atomic ratios of (CO2 + CO)/CO = 6 and (CO2 + CO)/N2 = 0.21 were applied. Additionally, partial upgrading of the produced heavy oil was observed.

Combustion tube experiments on key factors controlling the combustion process of air injection with light oil reservoir

High pressure air injection (HPAI) has unique advantages due to its rich gas source and unique high-energy displacement effect of the thermal front. Thermal effect of air injection after combustion is the key factor affecting the oil displacement effect. Combustion tube experiments are conducted to study the combustion characteristics of light oil and the influence of different factors on combustion process. We find that light oil (content of asphaltene is only 1.13%) can be ignited and combustion front can advance forward stably, which proves that the implement of HPAI in light oil reservoir can achieve good results. High temperature makes combustion more intense and the advancing of combustion front more stable. The experimental results show that when the air injection rate is low, low temperature oxidation of light oil will dominant, or the combustion front cannot successfully advance. But when the injection rate is too high, the combustion front moves forward too fast and gas channeling will occur. With pressure increasing, the solubility of O2 in oil increases, causing a more violent oxidation reaction. Increasing pressure can reduce the air/oil ratio and improve the utilization rate of O2. Thus, HPAI is more ideal for the reservoirs with high temperature and high pressure. And for a specific reservoir, an optimal injection rate exists. The conclusions of the research can provide references for field applications of HPAI in light oil reservoirs.

Response of Amaranthus cruenthus to Different Aeration Methods and Varying Irrigation Levels

Response of Amaranthus cruenthus to varying aeration methods (aeration of irrigation water (A1), air injection to crop root zone in soil before irrigation (A2), air injection to crop root zone in soil after irrigation (A3), and non aeration treatment (A0)) and irrigation levels (100% field capacity (FC) (W0), 75% FC (W1), 65% FC (W2) and 55 % FC (W3) were investigated. The results showed that varying irrigation as well as aeration levels had significant effects on the height of A. cruenthus while no significant difference was obtained in number of leaves across the field capacities during the growing period. The findings of this work showed that A. cruenthus was not sensitive to air treatment as expected. This is because lower number of leaves were obtained when air was either injected into the soil before or after irrigation as well as when air was injected into irrigation water at 4 and 7 weeks after planting. Plant height was maximum when no air was introduced to the plant at 4 Weeks After Planting. However, the number of leaves were highest at 65% FC throughout the growing period. The shoot, root and whole plant fresh weight were all significantly influenced by the aeration treatments but not FC except the root fresh weight. The edible yield (shoot fresh weight) was highest (48.55g) at 100% FC (W0). Also, when the irrigation water was injected with air (A1), the highest edible yield of 57.33 g was obtained. The highest Water Use Efficiency was exhibited at 100% FC (W0) while aeration of irrigation water (A1) gave the highest (26.06) Air Use E. 65% field capacity is best for planting A. cruenthus without negatively affecting the yield.