Oxygen Supply Method Research Articles

An attachment oxygen supply method for improving the sleep space environment in the Tibetan Plateau

The hypoxic environment results in common sleep problems for the local inhabitants of the Tibetan Plateau. Based on attachment ventilation, this study proposed an attachment oxygen supply device (AOSD) to improve the sleep space environment. The field tests were conducted in Lhasa to verify the oxygen supply effect of the AOSD and compared it with the traditional diffusive oxygen supply device (T-DOSD). The field tests were divided into two segments: the test of environmental parameters within the bedroom and the physiological parameters of the subjects. The results showed that the AOSD could create a comfortable oxygen-enriched environment for sleep space. At an oxygen flow of 10 L/min, compared to the initial oxygen concentration in the breathing zone, the oxygen concentration in the breathing zone is increased to 26.1% with the AOSD and 22.0% with the T-DOSD. When the oxygen flow is the same at 10 L/min, the AOSD increases oxygen concentration in the breathing zone by 4.1% compared to utilizing the T-DOSD. In addition, there was a decrease in heart rate and an increase in arterial oxygen saturation of subjects utilizing the AOSD. Therefore, the AOSD oxygen supply effect was further verified. The research contributes to improving both the sleep space environment and the sleep quality for inhabitants in an effective and energy-saving approach.

Mechanical Improvement of Gas Monitoring System in Monoplace Hyperbaric Chamber to Advance the Safety and Efficacy.

A Monoplace hyperbaric chamber delivers oxygen to the patient's tissues through breathing. Gas monitoring inside the chamber is important because oxygen (O2) is consumed, and carbon dioxide (CO2) is increased because treatment is performed in a closed volume. This study aimed to advance the safety and efficacy of the monoplace hyperbaric chamber (MHC) through mechanical improvement in a gas monitoring system (GMS). First, as the oxygen supply method was changed to the direction of the patient's face, it was compared the values of O2, CO2, humidity, and temperature were measured in the MHC and the GMS when operating at 2.0 atmosphere absolute (ATA) and 3.0 ATA. Second, to evaluate the effects of variables across measuring time, it was analyzed in a 3-way repeated measure ANOVA (10 min.×20 min.×30 min.). Lastly, the values before and after the optimization of the MHC were compared by applying a cooler to prevent temperature rise inside the MHC. In 2.0 ATA, the average humidity was higher in the MHC than in the GMS (p<0.001). Also, the average temperature was lower in the MHC than in the GMS (p<0.001). In 3.0 ATA, the average CO2 and humidity were higher in the MHC than in the GMS, respectively (p<0.001, p=0.004). The 3-way repeated measures ANOVA revealed a significant difference in most main and interacted factors (p<0.05). O2 and temperature, comparing before and after MHC optimization, revealed a significant difference (p<0.05). Few studies have verified safety and effectiveness by evaluating the pressure, oxygen concentration, etc. of a monoplace hyperbaric chamber. Further research is expected to verify the effectiveness of providing comfort to patients receiving hyperbaric oxygen treatment and increase the treatment effect.

A novel oxygen-enriched method for sentry buildings on plateaus based on an attached jet

Due to the existence of windows and the weak thermal resistance of building envelopes, the sentry building is easily affected by the low-oxygen and low-temperature environment at high-altitudes, which affects the work efficiency, cognitive ability and comfort of personnel. This study proposed a novel oxygen supply method suitable for plateau sentry buildings based on attached jet theory, which can achieve coupling control of the thermal and oxygen environment. The computational fluid dynamics (CFD) method was adopted to study the effect of air supply parameters and oxygen supply concentration on environment creation. The results showed that the environmental creation method could efficiently create the local environment. In addition, a nonuniform oxygen environment is created indoors. That is, the oxygen concentration in the head area is greater than that in the non-head area. It greatly improved the utilization rate of oxygen resources. The influence of the air supply velocity on the indoor environment creation effect is greater than that of the air supply temperature. The effect of creating a local oxygen environment is proportional to the concentration of oxygen supplied. The optimal air supply parameters are an air supply velocity (V) of 3 m/s, air supply temperature (Ts) of 30 °C, and oxygen supply concentration (C) of 90%, with the highest oxygen-enriched velocity of 1.598%/min. The research conclusions will provide new ideas for local environmental control methods in sentry buildings on the plateau and expand to actual projects to solve the problem of engineering application.

Study on the Optimization and Oxygen-Enrichment Effect of Ventilation Scheme in a Blind Heading of Plateau Mine.

There are abundant mineral resources in plateau areas, but it is difficult to extract them safely because the problem of hypoxia in plateau mines seriously affects the life and health of workers. In order to address the problem of hypoxia in the blind heading of a plateau metal mine, a three-dimensional roadway model was established based on field data of the Pulang copper mine in Yunnan province, China. The computational fluid dynamics (CFD) method was used to explore the optimal type of oxygen supply duct outlet, and to reveal the oxygen diffusion law influencing different ventilation factors. Grey correlation analysis was used to study the correlation values of the ventilation factors on the oxygen-enrichment effect in blind headings, such as forcing duct position, exhausting duct position, and extraction pressure ratio. The results demonstrated that the oxygen-enrichment effect of a slit oxygen outlet was better than that of the traditional oxygen supply method. When the direction of the oxygen outlet hole was 30° and the height above the roadway floor was 1.95 m, the oxygen increase effect was better than other forms of oxygen supply duct outlets. Grey correlation analysis revealed that the major influencing factors of the oxygen-enrichment effect in the roadway of the plateau mine, were, in descending order, as follows: forcing duct position, extraction pressure ratio, and exhausting duct position. This study has a positive guiding significance for improving the respiration environment in blind headings of plateau mines.

Experimental and Numerical Model Investigations of Oxygen-Enriched Characteristics in Air-Conditioned Rooms

People who live and work in air-conditioned rooms with micro-hypoxia are prone to sick building syndrome (SBS). Enriching oxygen into an air-conditioned room to increase the oxygen concentration can improve indoor air quality (IAQ) and reduce ventilation to save building energy consumption. In the present paper, the number and diameter of the oxygen supply vents, the oxygen supply flow rate, the oxygen supply method and the air flow organization form were comparatively studied using a numerical model. The results were compared with the experiments results in un-air-conditioned rooms, which showed that this model can give a favorable prediction. The results show that the maximum axial velocity decreases with the increase of the axial distance under air-conditioned conditions. The relationship between the oxygen-enriched area and the oxygen flow rate is obtained by fitting. The diameter of the oxygen supply pipe is 0.006 m, and when oxygen supply methods 1# and 4# are adopted, the oxygen-enriched area is F = 0.4 + 0.383 Q and F = 0.237 + 0.8 Q, respectively.

A novel point source oxygen supply method for sleeping environment improvement at high altitudes

The hypoxic environment at high altitudes causes various sleep disorders. Diffuse oxygen enrichment is an effective way to alleviate sleep disorders and improve the built environment in high altitude areas. In this study, a novel point source local diffuse oxygen supply method was proposed to improve the sleeping oxygen environment. The oxygen supply performance was investigated by the computational fluid dynamics (CFD) method including the oxygen concentration and air velocity distributions. A sleeping experiment was conducted on the plateau to validate the CFD model. The occupied zone including the inhalation zone and the active zone was defined. The results showed that the oxygen concentration showed a rapid rise, then decreased slowly, and finally tended to be stable. The oxygen concentration after stabilization was remarkably influenced by indoor ventilation rate. The sleeping environment’s improvement was examined considering the oxygen enrichment efficiency, uniformity, stability and human comfort demand. The optimal strategies were recommended with a ventilation rate of 1 air change per hour, supplied oxygen concentration of 90%, and jet distance of 0.50 m. The study contributes to improving the oxygen environment and human sleep quality in an effective and energy-saving approach to the sustainable development of buildings in high altitude areas.

Effect of oxygen supply method on the performance of a micro gas turbine-based triple combined cycle with oxy-combustion carbon capture

There is increasing interest in zero-carbon-emission power to prevent global warming. This study investigated an effective way to minimize the efficiency penalty and achieve near-zero carbon emission in a small-scale triple combined cycle. The power block of the cycle includes a solid oxide fuel cell, micro gas turbine, and organic Rankine cycle. The three oxy-combustion capture systems are a semi-closed cycle, a cycle using an ion transport membrane, and a cycle where the membrane is replaced with an air separation unit. A parametric analysis was performed to determine an optimal pressure ratio for each cycle. The performance characteristics of the three cycles and a cycle with conventional post-combustion capture were compared. It was found out that the cycle using an air separation unit is more efficient than the other two cycles and captures highly pure carbon dioxide. The efficiency penalty due to carbon capture is only 4.4%, resulting in 58% net efficiency. The most significant finding is that using the cryogenic air separation unit is more favorable than using the ion transport membrane to separate oxygen in a small triple combined cycle operating at low pressure, in contrast to one with high pressure.

Effective oxygen supply method for oil-contaminated soil remediation in bio-pile system using numerical analysis

Effective oxygen supply method for oil-contaminated soil remediation in bio-pile system using numerical analysis

Mathematical model for coal conversion in supercritical water: reacting multiphase flow with conjugate heat transfer

Providing heat for supercritical water gasification (SCWG) of coal by coupling subsequent products oxidation in integrated supercritical water reactor (ISWR) provides an effective method for directional control of temperature field and avoids excessive hot spots caused by uniform heating. An exploratory numerical model incorporating particle-fluid flow dynamics, multispecies transport and thermal coupling between endothermic coal gasification and exothermic product oxidation was established to simulate the reacting multiphase flow process of coal conversion in a novel lab-scale ISWR. An eleven-lump kinetic model was proposed for the prediction of chemical reactions. And the thermal coupling relationship was described by conjugate heat transfer boundary conditions (BC). Detailed physical and chemical field distribution in ISWR were analyzed and influence factors were discussed. The results showed that oxidation of gas products as inner heat source could promote the gasification reaction with only slight or even little maximum temperature increase of the pressure-bearing wall. Coal feeding rate and oxygen supply method significantly affected the field distribution. The multi-injection compressed-air supply method provided a more uniform temperature field but would reduce heat transfer temperature difference. The carbon gasification efficiency (CGE) in the gasification zone could easily reach up to 97% under mild conditions (less than 650 °C).

Process development of itaconic acid production by a natural wild type strain of Aspergillus terreus to reach industrially relevant final titers.

Itaconic acid is a promising organic acid and is commercially produced by submerged fermentation of Aspergillus terreus. The cultivation process of the sensitive filamentous fungus has been studied intensively since 1932, with respect to fermentation media components, oxygen supply, shearing rate, pH value, or culture method. Whereas increased final titers were achieved over the years, the productivity has so far remained quite low. In this study, the impact of the pH on the itaconic acid production was investigated in detail. The pH during the growth and production phase had a significant influence on the final itaconic acid concentration and pellet diameter. The highest itaconic acid concentration of 160g/L was achieved at a 1.5-L scale within 6.7days by raising and controlling the pH value to pH 3.4 in the production phase. An ammonia solution and an increased phosphate concentration were used with an itaconic acid yield of 0.46 (w/w) and an overall productivity of 0.99g/L/h in a fed-batch mode. A cultivation with a lower phosphate concentration resulted in an equal final concentration with an increased yield of 0.58 (w/w) after 11.8days and an overall productivity of 0.57g/L/h. This optimized process was successfully transferred from a 1.5-L scale to a 15-L scale. After 9.7days, comparable pellet morphology and a final concentration of 150g/L itaconic acid was reached. This paper provides a process strategy to yield a final titer of itaconic acid from a wild-type strain of A. terreus which is in the same range as the well-known citric acid production.

Exergy and energy analysis of a load regulation method of CVO of air separation unit

Generally in the Chinese iron and steel industry, the electricity consumption of cryogenic air separation unit (ASU) is about 14% of the overall electricity use. To reduce the electricity consumption, the combined variable oxygen (CVO) supply method for ASU is proposed. The exergy calculation program for ASU was developed and the detailed analysis of CVO method was performed. The results show that the general exergy efficiency (GEE) of ASU combined with a liquefaction unit is increased by 11 %–31 %. The consumption of unit oxygen, the total electricity consumption and the overall consumption of unit oxygen (OCUO) was compared. The OCUO is a suitable method to evaluate the energy-saving potential of CVO. Compared with the load regulation method of Automatic Load Control (ALC), the OCUO and the unit consumption of compression of CVO reduced more than 4.47% and 30%, respectively. It means that CO2 emission of every reduction 1% of gaseous oxygen release in a year in Chinese iron and steel industry will contribute approximately 0.75% to the 2020s CO2 emission reduction target of China.

Stereospecific production of 9R-hydroxy-10E,12Z-octadecadienoic acid from linoleic acid by recombinant Escherichia coli cells expressing 9R-lipoxygenase from Nostoc sp. SAG 25.82

Abstract One of the most significant properties of lipoxygenase (LOX) as a biocatalyst is its stereo-selective oxygenation. In this study, the stereo-specific production of 9R-hydroxy-10E,12Z-octadecadienoic acid (9R-HODE) from linoleic acid was achieved using whole recombinant Escherichia coli cells expressing LOX from Nostoc sp. SAG 25.82. The optimal conditions for the production of 9R-HODE were pH 7.5, 25 °C, 40 g l−1 cells, 15 g l−1 linoleic acid, 2% (v/v) methanol, 1 working volume/oxygen volume/min (vvm) oxygenation rate, and 250 rpm agitation speed in 500 ml-baffled flask containing a working volume of 50 ml. Under these optimized conditions, whole recombinant cells expressing 9R-LOX protein produced 14.3 g l−1 9R-HODE for 1 h, with a conversion yield of 95% (w/w) and a productivity of 14.3 g l−1 h−1. The oxygen supply method significantly influenced stereo- and regio-selectivity of the oxygenation of linoleic acid. Among the oxygen supply methods tested, oxygenation (1 vvm) with agitation (250 rpm) resulted in the highest 9R/13S-HODE ratio of the products at 96:4. This is the first application using whole recombinant cells harboring R-specific LOX for the stereo-selective production of an R-specific hydroxy fatty acid.

Effect of Different PCI Practice on the Texture Obtained during Reduction of Iron Oxide Pellets

In modern blast furnace ironmaking, producers continuously strive to reduce coke consumption by replacing coke with e.g., an increased amount of injected pulverized coal. A change in pulverized coal injection rate (PCR) and injection coal type will influence the in-furnace conditions and thus the reduction of iron oxides. In the present study, the reduction behaviour of olivine pellets and textures formed were investigated in the LKAB Experimental Blast Furnace (EBF) and in laboratory scale. In the EBF, effects of injection of an low-volatile (LV) and an high-volatile (HV) coal type at different PCR while two types of oxygen supply methods were employed were investigated. The choice of injection coal type was conclusive for the Femet texture formed during reduction, extent of Femet carburization and K distribution in the pellets. The amount of volatile matters in the coal type had a greater effect on the reduction properties than the PCR and oxygen supply method. Laboratory experiments simulating PCR, based on measurements in the EBF, showed that the initial reduction conditions, in terms of temperature level and reduction gas composition, determined the pellet texture up to a reduction degree of at least 60%. The tests carried out in the EBF showed that the pellets were well suited for blast furnace reduction under all the investigated process conditions. The laboratory tests supported this conclusion.

Development of High Efficient Oxygen Supply Method by Using Contacting Water-Liquid film with Air

Surface transfer and bubble transfer both contribute significantly to oxygen transfer in a conventional aeration system. However, bubble transfer plays the primary role of oxygen transfer. In the present study, the mere surface transfer is replaced by directly contacting liquid film designed elegantly with air. Liquid film aeration system is successfully developed on a laboratory scale. The experimental results from single-pass aeration mode show that the dissolved oxygen concentration in deoxygenate water reaches up to 95 % or higher, as compared with the saturation concentrations of the dissolved oxygen while using this novel aeration system. Meanwhile, an increase in oxygen mass transfer rate by 30% can be achieved in comparison with conventional aeration system. Moreover, the volumetric mass transfer coefficient for liquid film-forming apparatus (KLal) is found to be as much as 5 times higher than that for water surface in a conventional aeration test.

Catalytic Activity of Polyaniline in the Molecular Oxygen Reduction: Its Nature and Mechanism

By comparing experiments in air and an inert atmosphere, additional evidence for the polyaniline catalytic action on the air oxygen electroreduction is obtained. The action is compared with that of graphite substrates under the same conditions. The effect of the oxygen supply method and the polyaniline film thickness (weight) on the oxygen reduction rate is evaluated. To elucidate the nature of the polyaniline catalytic activity, quantum-chemical modeling of polyaniline and its adsorption complexes with oxygen is carried out. According to calculations, molecular oxygen can be reversibly chemisorbed at the polyaniline surface that serves as a donor of electron density. The bonding order for the O2*molecules chemisorbed at polyaniline decreases by ∼30% and the bond length increases by 24%. Thus, oxygen molecules acquire higher activity in a chemisorbed state and can then participate in the reduction more actively.

Effects of Oxygen Supply Methods on the Performance of a Sequencing Batch Reactor for High Ammonium Nitrification

High ammonium nitrification was studied in a sequencing batch reactor (SBR) with two different oxygen supply methods: controlled oxygen supply rates (dissolved oxygen [DO] in the reactor controlled between 2 and 3 mg/L) and uncontrolled oxygen supply rates (DO in the reactor uncontrolled and changed ambiently with oxygen use rate). Experimental results showed that oxygen supply methods have significant effects on SBR performance for high ammonium nitrification. With the controlled oxygen supply method, ammonium and nitrite oxidations took place simultaneously. With the uncontrolled oxygen supply method, ammonium oxidation proceeded smoothly during the low DO period of a cycle; however, nitrite oxidation was at first completely inhibited at low‐DO but recovered during the high DO period of the same cycle. Ammonium and nitrite were oxidized sequentially during a cycle in SBR. Ammonium oxidizers developed an ability to endure the fluctuation of DO, but nitrite oxidizers did not. Extensive starvation under high DO concentrations plays an important role in ammonium oxidation under low DO conditions.

Optimization of Dissolved Oxygen Supply Method for Maximum Virginiamycin Production

To maximize the production of virginiamycin (VM and VS) which is commercially used as an antibiotic mixed in animal feed, an empirical approach was employed in the batch culture of Streptomyces virginiae. Here, effects of Dissolved Oxygen (DO) concentration and/or DO supplying condition such as pure oxygen supply and agitation speed changes on the maximum cell concentration at the production phase as well as production activity of virginiamycin were investigated. In order to keep DO concentration in the fermenter at a certain level, either agitation speed or inlet oxygen concentration of supplying gas can be manipulated. It was found that the increase of agitation speed gave positive effect on antibiotics productivity apart from the controlled DO concentration. Optimum DO concentration and agitation speed including VB-C addition was determined for maximize virginiamycin production.

A new oxygen supply method for simultaneous organic carbon removal and nitrification by a one-stage biofilm process

A new oxygen supply method to biofilm is proposed for simultaneous organic carbon removal and nitrification. The main feature of the method is use of hydrophobic porous membrane or oxygen enrichment membrane as substratum of biofilm. In the biofilm formed on oxygen permeable membrane, oxygen is supplied from the bottom to the surface of the biofilm through the membrane while organic pollutants are supplied from the surface to the bottom of the biofilm. The oxygen supply method allows nitrifiers near the bottom region to grow with less competition from BOD oxidizers. The microbial population was investigated in the biofilm formed on hydrophobic microfilter. Nitrifiers grew mainly in the bottom region while denitrifiers grew in the middle region of the biofilm formed on the membrane. Simultaneous organic carbon removal and nitrification were carried out successfully by the biofilm. Furthermore, the potential of the new oxygen supply method was demonstrated with the biofilm formed on an oxygen enrichment-type biomass carrier in a single-stage treatment of domestic wastewater. The nitrification rate was about 1.9 g/m2d and was comparable to that in the conventional biofilm process designed especially for nitrification.

A new oxygen supply method for simultaneous organic carbon removal and nitrification by a one-stage biofilm process

A new oxygen supply method to biofilm is proposed for simultaneous organic carbon removal and nitrification. The main feature of the method is use of hydrophobic porous membrane or oxygen enrichment membrane as substratum of biofilm. In the biofilm formed on oxygen permeable membrane, oxygen is supplied from the bottom to the surface of the biofilm through the membrane while organic pollutants are supplied from the surface to the bottom of the biofilm. The oxygen supply method allows nitrifiers near the bottom region to grow with less competition from BOD oxidizers. The microbial population was investigated in the biofilm formed on hydrophobic microfilter. Nitrifiers grew mainly in the bottom region while denitrifiers grew in the middle region of the biofilm formed on the membrane. Simultaneous organic carbon removal and nitrification were carried out successfully by the biofilm. Furthermore, the potential of the new oxygen supply method was demonstrated with the biofilm formed on an oxygen enrichment-type biomass carrier in a single-stage treatment of domestic wastewater. The nitrification rate was about 1.9 g/m2d and was comparable to that in the conventional biofilm process designed especially for nitrification.

Oxygen Supply Method Using Gas-Permeable Film for Wastewater Treatment

Gas-permeable film can separate air and water, and at the same time, let oxygen diffuse from the air to the water through the film. An oxygen supply method using this film was investigated for the purpose of reducing energy consumption for wastewater treatment. The oxygen transfer rate was measured for the cases with or without biofilm, which proved the high rate of oxygen transfer in the case with nitrifying biofilm which performed nitrification. When the Gas-permeable film with nitrifying biofilm was applied to the treatment of wastewater, denitrifying biofilm formed on the nitrifying biofilm, and simultaneous nitrification and denitrification occurred, resulting in the high rate of organic matter and T-N removal (7 gTOC/m2/d and 4 gT-N/m2/d, respectively). However, periodic sloughing of the denitrifying biofilm was needed to keep the oxygen transfer rate high. Energy consumption of the process using the film in the form of tubes was estimated to be less than 40% of that of the activated sludge process.