Osmotic stress caused by low-temperature,drought and salinity was a prevalent abiotic stress in plant that severely inhibited plant development and agricultural yield,particularly in tea plant.Jasmonic acid(JA)is an i...Osmotic stress caused by low-temperature,drought and salinity was a prevalent abiotic stress in plant that severely inhibited plant development and agricultural yield,particularly in tea plant.Jasmonic acid(JA)is an important phytohormone involving in plant stress.However,underlying molecular mechanisms of JA modulated osmotic stress response remains unclear.In this study,high concentration of mannitol induced JA accumulation and increase of peroxidase activity in tea plant.Integrated transcriptome mined a JA signaling master,MYC2 transcription factor is shown as a hub regulator that induced by mannitol,expression of which positively correlated with JA biosynthetic genes(LOX and AOS)and peroxidase genes(PER).CsMYC2 was determined as a nuclei-localized transcription activator,furthermore,ProteinDNA interaction analysis indicated that CsMYC2 was positive regulator that activated the transcription of CsLOX7,CsAOS2,CsPER1 and CsPER3via bound with their promoters,respectively.Suppression of CsMYC2 expression resulted in a reduced JA content and peroxidase activity and osmotic stress tolerance of tea plant.Overexpression of CsMYC2 in Arabidopsis improved JA content,peroxidase activity and plants tolerance against mannitol stress.Together,we proposed a positive feedback loop mediated by CsMYC2,CsLOX7 and CsAOS2 which constituted to increase the tolerance of osmotic stress through fine-tuning the accumulation of JA levels and increase of POD activity in tea plant.展开更多
Improved liquid rocket engine cycles were proposed and analyzed via comparison with existing staged combustion and gas-generator cycles.The key features of the proposed cycles are regenerative cooling of thrust chambe...Improved liquid rocket engine cycles were proposed and analyzed via comparison with existing staged combustion and gas-generator cycles.The key features of the proposed cycles are regenerative cooling of thrust chamber by oxygen and subsequent use of this oxygen for driving one or two oxygen pumps.The fuel pump(s)are driven in a conventional manner,for example,using a fuel-rich gas-generator cycle.Comparison with staged combustion cycle based on oxygen-rich pre-burner showed that one of the proposed semi-expander cycles has a specific impulse only on 0.4%lower while providing much lower oxygen temperature,more efficient tank pressurizing system and built-in roll control.This semi-expander cycle can be considered as a more reliable and cost-effective alternative of staged combustion cycle.Another semi-expander cycle can be considered as an improvement of gas-generator cycle.All proposed semi-expander cycles were developed as a derivative of thrust chamber regenerative cooling performed by oxygen.Analysis of existing oxygen/kerosene engines showed that replacing of kerosene regenerative cooling with oxygen allows a significant increase of achievable specific impulse,via optimization of mixture ratio.It is especially the case for upper stage engines.The increasing of propellants average density can be considered as an additional benefit of mixture ratio optimization.It was demonstrated that oxygen regenerative cooling of thrust chamber is a feasible and the most promising option for oxygen/kerosene engines.Combination of oxygen regenerative cooling and semi-expander cycles potentially allows creating the oxygen/kerosene propulsion systems with minimum specific impulse losses.It is important that such propulsion systems can be fully based on inherited and well-proven technical solutions.A hypothetic upper stage engine with thrust 19.6 kN was chosen as a prospective candidate for theoretical analysis of the proposed semi-expander cycles.The newly-developed software RECS was used for the comparative analysis of engine cycles.展开更多
This article reports the extraction of zirconium (IV) from aqueous HC1 solution by tri-octyl amine (TOA), Cyanex 921, and their binary mixture using kerosene as the diluent. The effect of some parameters on the ex...This article reports the extraction of zirconium (IV) from aqueous HC1 solution by tri-octyl amine (TOA), Cyanex 921, and their binary mixture using kerosene as the diluent. The effect of some parameters on the extraction of Zr(IV) was investigated such as equilibration time, aqueous phase acidity, extractant molarity, chloride ion concentration, nature of diluents, and temperature. The extraction of Zr(IV) was found to be 99% from 7.5 M HC1 using the mixture of extractants containing 0.1 M TOA and 0.02 M Cyanex 921 in kerosene. Kerosene was found to be the effective diluent for the extraction of Zr(IV) with the binary mixture of TOA and Cyanex 921. The positive enthalpy change and positive entropy change in the binary extraction system show the endothermic process with an increase in entropy. Stripping of Zr(IV) from the loaded organic phase containing the mixture of TOA (0.1 M) and Cyanex 921 (0.02 M) indicates that HNO3 and Na2CO3 are the best stripping agents.展开更多
Supersonic model combustors using two-stage injections of supercritical kerosene were experimentally investigated in both Mach 2.5 and 3.0 model combustors with stagnation temperatures of approximately 1,750 K. Superc...Supersonic model combustors using two-stage injections of supercritical kerosene were experimentally investigated in both Mach 2.5 and 3.0 model combustors with stagnation temperatures of approximately 1,750 K. Supercritical kerosene of approximately 760 K was prepared and injected in the overall equivalence ratio range of 0.5-1.46. Two pairs of integrated injector/flameholder cavity modules in tandem were used to facilitate fuel-air mixing and stable combustion. For single-stage fuel injection at an upstream location, it was found that the boundary layer separation could propagate into the isolator with increasing fuel equivalence ratio due to excessive local heat release, which in turns changed the entry airflow conditions. Moving the fuel injection to a further downstream location could alleviate the problem, while it would result in a decrease in combustion efficiency due to shorter fuel residence time. With two-stage fuel injections the overall combustor performance was shown to be improved and kerosene injections at fuel rich conditions could be reached without the upstream propagation of the boundary layer separation into the isolator. Furthermore, effects of the entry Mach number and pilot hydrogen on combustion performance were also studied.展开更多
In order to study the instability propagation characteristics of the liquid kerosene rotating detonation wave(RDW),a series of experimental tests were carried out on the rotating detonation combustor(RDC)with air-heat...In order to study the instability propagation characteristics of the liquid kerosene rotating detonation wave(RDW),a series of experimental tests were carried out on the rotating detonation combustor(RDC)with air-heater.The fuel and oxidizer are room-temperature liquid kerosene and preheated oxygenenriched air,respectively.The experimental tests keep the equivalence ratio of 0.81 and the oxygen mass fraction of 35%unchanged,and the total mass flow rate is maintained at about 1000 g/s,changing the total temperature of the oxygen-enriched air from 620 K to 860 K.Three different types of instability were observed in the experiments:temporal and spatial instability,mode transition and re-initiation.The interaction between RDW and supply plenum may be the main reason for the fluctuations of detonation wave velocity and pressure peaks with time.Moreover,the inconsistent mixing of fuel and oxidizer at different circumferential positions is related to RDW oscillate spatially.The phenomenon of single-double-single wave transition is analyzed.During the transition,the initial RDW weakens until disappears,and the compression wave strengthens until it becomes a new RDWand propagates steadily.The increased deflagration between the detonation products and the fresh gas layer caused by excessively high temperature is one of the reasons for the RDC quenching and re-initiation.展开更多
The convective heat transfer of supercritical-pressure RP-3(Rocket Propellant 3)aviation kerosene in a horizontal circular tube has been numerically studied,focusing mainly on the non-uniform heat transfer deteriorati...The convective heat transfer of supercritical-pressure RP-3(Rocket Propellant 3)aviation kerosene in a horizontal circular tube has been numerically studied,focusing mainly on the non-uniform heat transfer deterioration along the circumferential direction.The governing equations of mass,momentum and energy have been solved using the pressure-based segregated solver based on the finite volume method.The re-normalization group(RNG)k-εturbulence model with an enhanced wall treatment was selected.Considering the heat conduction in the solid wall,the mechanism of heat transfer deterioration and the buoyancy effect on deteriorated heat transfer were discussed.The evolution of secondary flow was analyzed.Effects of the outer-wall heat flux,mass flux,pressure and tube thermal conductivity on heat transfer were investigated.Moreover,the buoyancy criterion and the heat transfer correlation were obtained.Results indicate that the poor flow performance of near-wall fluid causes the pseudo-film boiling,further leads to the heat transfer deterioration.The strong buoyancy has an effect of enhancing the heat transfer at the bottom of tube,and weakening the heat transfer at the top of tube,which results in the non-uniform inner-wall temperature and heat flux distributions.Decreasing the ratio of outer-wall heat flux and mass flux,increasing the pressure could weaken the heat transfer difference along the circumferential direction,while the effect of thermal conductivity of tube on the circumferential parameters distributions is more complicated.When the buoyancy criterion of(Grq/Grth)max≤0.8 is satisfied,the effect of buoyancy could be ignored.The new correlations work well for non-uniform heat transfer predictions.展开更多
In this paper,the kerosene/air rotating detonation engines(RDE)are numerically investigated,and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE inc...In this paper,the kerosene/air rotating detonation engines(RDE)are numerically investigated,and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation,instabilities,and propulsive performance.A hybrid MPI t OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC)systems.A series of cases with the total pressure of 1 MPa,1.5 MPa,2 MPa,and the equivalence ratio of 0.9,1,1.4 are simulated.On one hand,the total pressure shows a significant impact on the instabilities of rotating detonation waves.The instability phenomenon is observed in cases with low total pressure(1 MPa)and weakened with the increase of the total pressure.The total pressure has a small impact on the detonation wave velocity and the specific impulse.On the other hand,the equivalence ratio shows a negligible influence on the instabilities,while it affects the ignition process and accounts for the detonation velocity deficit.It is more difficult to initiate rotating detonation waves directly in the lean fuel operation condition.Little difference was observed in the thrust with different equivalence ratios of 0.9,1,and 1.4.The highest specific impulse was obtained in the lean fuel cases,which is around 2700 s.The findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE.展开更多
In this paper, compressible flow of aviation kerosene at supercritical conditions has been studied both numerically and experimentally. The thermophysical properties of supercritical kerosene are calculated using a 10...In this paper, compressible flow of aviation kerosene at supercritical conditions has been studied both numerically and experimentally. The thermophysical properties of supercritical kerosene are calculated using a 10- species surrogate based on the principle of extended corresponding states (ECS). Isentropic acceleration of supercritical kerosene to subsonic and supersonic speeds has been analyzed numerically. It has been found that the isentropic relationships of supercritical kerosene are significantly dif- ferent from those of ideal gases, A two-stage fuel heating and delivery system is used to heat the kerosene up to a tem- perature of 820 K and pressure of 5.5 MPa with a maximum mass flow rate of 100 g/s. The characteristics of supercritical kerosene flows in a converging-diverging nozzle (Laval nozzle) have been studied experimentally. The results show that stable supersonic flows of kerosene could be established in the temperature range of 730 K-820 K and the measurements in the wall pressure agree with the numerical calculation.展开更多
A brief review of the recent advances in kerosene-fueled supersonic combustion modeling is present by comparing the fuels,reviewing the kinetic mechanisms,and introducing recent modeling results.The advantages and dis...A brief review of the recent advances in kerosene-fueled supersonic combustion modeling is present by comparing the fuels,reviewing the kinetic mechanisms,and introducing recent modeling results.The advantages and disadvantages of hydrogen and kerosene for the scramjet combustor are compared to show that kerosene is a more viable fuel option for a Mach number range of 4-8.However,detailed kinetic mechanisms for kerosene,which usually contain thousands of elementary reactions,must be significantly reduced for use in modeling.As of this writing,the smallest skeletal kerosene mechanism has only 19 species and 53 reversible reactions.In contrast to pioneer models based on global chemistry,the current kerosene-fueled supersonic combustion models based on reduced/skeletal chemistry are classified as second-stage.The influence of kinetic mechanisms,global equivalence ratios,inlet Mach number,geometric shape,and domain symmetry are reviewed based on high-fidelity models and available measurements.With the advances in computational technology,models with accurate descriptions of both flow and chemistry are becoming a promising,indispensable approach for the study of supersonic combustion.展开更多
In this study, kerosene fuel-rich gas produced by the combustion in the gas generator was used as the fuel and oxygen-rich air was used as the oxidant to investigate the propagation characteristics of the rotating det...In this study, kerosene fuel-rich gas produced by the combustion in the gas generator was used as the fuel and oxygen-rich air was used as the oxidant to investigate the propagation characteristics of the rotating detonation wave (RDW). The initiation of the kerosene fuel-rich gas and propagation process of the RDW were analyzed. The influences of the oxygen content in the oxidizer, kerosene mass flow rate of the gas generator, and temperature of the kerosene fuel-rich gas on the propagation process of the RDW were studied. The experimental results revealed that the propagation velocity of the RDW could be improved by increasing the three parameters mentioned above with the kerosene mass flow rate as the strongest factor. The minimum oxygen content that could successfully initiate and maintain the stable propagation of the RDW was 32%, achieving the RDW velocity of 1141.9 m/s. The RDW mainly propagated as two-counter rotating waves and a single wave when the equivalent ratios were 0.62–0.79 and 0.85–0.87, respectively. The highest RDW velocity of 1637.2 m/s was obtained when the kerosene mass flow rate, oxygen content, and equivalent ratio were 74.6 g/s, 44%, and 0.87, respectively.展开更多
The oxidative desulfurization of a real refinery feedstock (i.e.,non-hydrotreated kerosene with total sulfur mass content of 0.16%) with a mixture of hydrogen peroxide and acetic acid was studied.The influences of var...The oxidative desulfurization of a real refinery feedstock (i.e.,non-hydrotreated kerosene with total sulfur mass content of 0.16%) with a mixture of hydrogen peroxide and acetic acid was studied.The influences of various operating parameters including reaction temperature (T),acid to sulfur molar ratio (nacid/nS),and oxidant to sulfur molar ratio (nO/nS) on the sulfur removal of kerosene were investigated.The results revealed that an increase in the reaction temperature (T) and nacid/nS enhances the sulfur removal.Moreover,there is an optimum nO/nS related to the reaction temperature and the best sulfur removal could be obtained at nO/nS=8 and 23 for the reaction temperatures of 25 and 60°C,respectively.The maximum observed sulfur removal in the present oxidative desulfurization system was 83.3%.展开更多
[Objective] The study aimed at selecting the predominant strains being able to degrade kerosene and studying its best growth conditions. [Method] Choosing kerosene as the only carbon source, we selected and separated ...[Objective] The study aimed at selecting the predominant strains being able to degrade kerosene and studying its best growth conditions. [Method] Choosing kerosene as the only carbon source, we selected and separated the predominant strains being able to degrade kerosene from the contaminated soil near petrochemical plants, and then optimized the grow conditions of the bacteria. [Result] The best conditions for the bacteria growth were determined as follows, that is, temperature was 30 ℃, pH=7, salinity was 2.5%, and the rotational speed of the thermostatic shake was 190 r/min. Under the optimal conditions, the degradation rate of kerosene by the bacteria cultured for three days reached 42.6%. [Conclusion] The research could provide scientific references for the restoration of polluted soil by kerosene.展开更多
Plastics wastes from a municipal solid waste (MSW) plant have a high-energy content and are suitable for fuel generation. Thermal cracking is one of the possible ways to obtain petrochemical feedstock from polymer was...Plastics wastes from a municipal solid waste (MSW) plant have a high-energy content and are suitable for fuel generation. Thermal cracking is one of the possible ways to obtain petrochemical feedstock from polymer wastes. Municipal waste plastic of LDPE conversion to kerosene grade fuel experiments were carried out under atmospheric conditions at temperatures between 150℃ and 420℃. Low density polyethylene (LDPE) plastic waste (Code #2) was thermally depolymerized in batch process into stainless steel reactor without adding catalyst. The maximum kerosene grade fuel yield is 30%, other grade fuel 60%, light gas 6% and left over residue 4%. The composition, sulphur and Btu value of liquid products were determined by ASTM method. Produced fuel was analyzed by Gas Chromatography and Mass Spectrometer and FT-IR. Very high conversions from LDPE waste plastic to kerosene grade fuel (up to 35%) were obtained while using this technique. Detailed product analyses and characterization lead to a reasonable explanation of reaction pathways and mechanisms.展开更多
1 Introduction As the lightest metal with the unique properties of energy production and storage,lithium is regarded as the new century energy metal.Lithium and its compounds were widely used in various industrial fie...1 Introduction As the lightest metal with the unique properties of energy production and storage,lithium is regarded as the new century energy metal.Lithium and its compounds were widely used in various industrial fields,especially in展开更多
Exposure to high PM10 by women and children for hours on a daily basis in poor ventilated kitchen may lead to respiratory morbidity among this vulnerable group. In Nigeria, data on the levels of air pollutants associa...Exposure to high PM10 by women and children for hours on a daily basis in poor ventilated kitchen may lead to respiratory morbidity among this vulnerable group. In Nigeria, data on the levels of air pollutants associated with kerosene stove combustion are very scarce. Like-wise little had been documented on the pulmonary health of women exposed to kerosene stove emission. This study was carried out to measure the levels of kerosene combustion emissions within kitchen environments and also assess the pulmonary function status of the exposed women at baseline. Particulate matter (PM10) and gaseous emissions (GE) were measured in six purposively selected clusters of regular kerosene stove users (KSU) using gravimetric sampler and gas monitors, respectively and their values compared with WHO guideline limits. 167 randomly selected KSU were surveyed to elicit their socio demographic features. A spirometer was used to assess the lung function status (FEV1) of 72 KSU in six neighbourhood kitchen clusters. Data were analysed using descriptive statistics, and Pearson’s correlation tests. Respondents’ mean age was 38 + 12.9 years. Mean duration of exposure to GE was 18.9 + 9.8 years. Mean PM10 was 248.1 + 14.1 μg/m3 and ten folds higher than WHO guideline limit of 25 μg/m3. Mean GE in ppm were: CO (0.00), CO2 (200.1 + 12.4), SO2 (0.01 + 0.00) and NO2 (0.00). Mean FEV1 among KSU was 2.0 + 0.5 litres which was significantly lower than the mean predicted value of 2.7 ± 0.5 litres. There was a negative correlation between PM10 and FEV1 (r = -0.7539, p > 0.05). Safer cooking methods and practices to obviate health hazards are advocated.展开更多
Score-StoveTM a clean-burning cooking stove that also generates electricity was tested using a pressurized kerosene burner. The Score-Stove works on the principle of thermo-acoustics to gen- erate small-scale electric...Score-StoveTM a clean-burning cooking stove that also generates electricity was tested using a pressurized kerosene burner. The Score-Stove works on the principle of thermo-acoustics to gen- erate small-scale electricity. The device having hot-end, cold-end and regenerator acts in a way similar to a stirling cycle generating acoustic power, which is then converted to electricity using a linear actuator. It can supply small power for applications such as LED lighting, mobile phone charging and radios particularly in rural areas without grid electricity as well as improving house- hold air pollution. After assessing the needs of the rural communities through a survey, tea-stalls and small restaurants owners were identified as clients with the most potential of using the stove in Bangladesh. Bangladesh University of Engineering and Technology ((BUET) modified a Score- Stove to use both wood and a pressurized kerosene burner of a design that is widely used for cooking in rural areas of Bangladesh. The design was adapted to meet performance needs such as: heating rate, cooking efficiency, energy distribution, electric power generation, exhaust emissions and time taken to boil water using standardized water boiling tests. Performance was also compared with conventional (non-electrically generating) stoves that use a pressurized kerosene burn- er. The Score-Stove performance was then evaluated while increasing the pressure of the sealed working fluid (air in this case) from atmospheric to about 1.4 bar. The pressurization was found to almost double the power generation. An arrangement for utilizing cooling water waste heat was also devised in order to improve the thermal performance of the stove by 18%. Technical deficiencies are documented and recommendations for improvements and future research in order to obtain wider end-user acceptance are made.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.32202542 and U20A2045)the Project of Major Science and Technology in Anhui Province(Grant No.202003a06020021)+2 种基金the Project of Science and Technology of Yunnan Province(Grant No.202102AE090038)Anhui Provincial Natural Science Foundation(Grant No.2108085QC121)the Natural Science Projects for Colleges and Universities in the Anhui Province(Grant No.KJ2021A0145)。
文摘Osmotic stress caused by low-temperature,drought and salinity was a prevalent abiotic stress in plant that severely inhibited plant development and agricultural yield,particularly in tea plant.Jasmonic acid(JA)is an important phytohormone involving in plant stress.However,underlying molecular mechanisms of JA modulated osmotic stress response remains unclear.In this study,high concentration of mannitol induced JA accumulation and increase of peroxidase activity in tea plant.Integrated transcriptome mined a JA signaling master,MYC2 transcription factor is shown as a hub regulator that induced by mannitol,expression of which positively correlated with JA biosynthetic genes(LOX and AOS)and peroxidase genes(PER).CsMYC2 was determined as a nuclei-localized transcription activator,furthermore,ProteinDNA interaction analysis indicated that CsMYC2 was positive regulator that activated the transcription of CsLOX7,CsAOS2,CsPER1 and CsPER3via bound with their promoters,respectively.Suppression of CsMYC2 expression resulted in a reduced JA content and peroxidase activity and osmotic stress tolerance of tea plant.Overexpression of CsMYC2 in Arabidopsis improved JA content,peroxidase activity and plants tolerance against mannitol stress.Together,we proposed a positive feedback loop mediated by CsMYC2,CsLOX7 and CsAOS2 which constituted to increase the tolerance of osmotic stress through fine-tuning the accumulation of JA levels and increase of POD activity in tea plant.
文摘Improved liquid rocket engine cycles were proposed and analyzed via comparison with existing staged combustion and gas-generator cycles.The key features of the proposed cycles are regenerative cooling of thrust chamber by oxygen and subsequent use of this oxygen for driving one or two oxygen pumps.The fuel pump(s)are driven in a conventional manner,for example,using a fuel-rich gas-generator cycle.Comparison with staged combustion cycle based on oxygen-rich pre-burner showed that one of the proposed semi-expander cycles has a specific impulse only on 0.4%lower while providing much lower oxygen temperature,more efficient tank pressurizing system and built-in roll control.This semi-expander cycle can be considered as a more reliable and cost-effective alternative of staged combustion cycle.Another semi-expander cycle can be considered as an improvement of gas-generator cycle.All proposed semi-expander cycles were developed as a derivative of thrust chamber regenerative cooling performed by oxygen.Analysis of existing oxygen/kerosene engines showed that replacing of kerosene regenerative cooling with oxygen allows a significant increase of achievable specific impulse,via optimization of mixture ratio.It is especially the case for upper stage engines.The increasing of propellants average density can be considered as an additional benefit of mixture ratio optimization.It was demonstrated that oxygen regenerative cooling of thrust chamber is a feasible and the most promising option for oxygen/kerosene engines.Combination of oxygen regenerative cooling and semi-expander cycles potentially allows creating the oxygen/kerosene propulsion systems with minimum specific impulse losses.It is important that such propulsion systems can be fully based on inherited and well-proven technical solutions.A hypothetic upper stage engine with thrust 19.6 kN was chosen as a prospective candidate for theoretical analysis of the proposed semi-expander cycles.The newly-developed software RECS was used for the comparative analysis of engine cycles.
文摘This article reports the extraction of zirconium (IV) from aqueous HC1 solution by tri-octyl amine (TOA), Cyanex 921, and their binary mixture using kerosene as the diluent. The effect of some parameters on the extraction of Zr(IV) was investigated such as equilibration time, aqueous phase acidity, extractant molarity, chloride ion concentration, nature of diluents, and temperature. The extraction of Zr(IV) was found to be 99% from 7.5 M HC1 using the mixture of extractants containing 0.1 M TOA and 0.02 M Cyanex 921 in kerosene. Kerosene was found to be the effective diluent for the extraction of Zr(IV) with the binary mixture of TOA and Cyanex 921. The positive enthalpy change and positive entropy change in the binary extraction system show the endothermic process with an increase in entropy. Stripping of Zr(IV) from the loaded organic phase containing the mixture of TOA (0.1 M) and Cyanex 921 (0.02 M) indicates that HNO3 and Na2CO3 are the best stripping agents.
基金supported by the National Natural Science Foundation of China (10672169, 10621202)
文摘Supersonic model combustors using two-stage injections of supercritical kerosene were experimentally investigated in both Mach 2.5 and 3.0 model combustors with stagnation temperatures of approximately 1,750 K. Supercritical kerosene of approximately 760 K was prepared and injected in the overall equivalence ratio range of 0.5-1.46. Two pairs of integrated injector/flameholder cavity modules in tandem were used to facilitate fuel-air mixing and stable combustion. For single-stage fuel injection at an upstream location, it was found that the boundary layer separation could propagate into the isolator with increasing fuel equivalence ratio due to excessive local heat release, which in turns changed the entry airflow conditions. Moving the fuel injection to a further downstream location could alleviate the problem, while it would result in a decrease in combustion efficiency due to shorter fuel residence time. With two-stage fuel injections the overall combustor performance was shown to be improved and kerosene injections at fuel rich conditions could be reached without the upstream propagation of the boundary layer separation into the isolator. Furthermore, effects of the entry Mach number and pilot hydrogen on combustion performance were also studied.
基金supported by the National Natural Science Foundation of China(Grant No.11802137,11702143 and 11802039)the Fundamental Research Funds for the Central Universities(No.30919011259).
文摘In order to study the instability propagation characteristics of the liquid kerosene rotating detonation wave(RDW),a series of experimental tests were carried out on the rotating detonation combustor(RDC)with air-heater.The fuel and oxidizer are room-temperature liquid kerosene and preheated oxygenenriched air,respectively.The experimental tests keep the equivalence ratio of 0.81 and the oxygen mass fraction of 35%unchanged,and the total mass flow rate is maintained at about 1000 g/s,changing the total temperature of the oxygen-enriched air from 620 K to 860 K.Three different types of instability were observed in the experiments:temporal and spatial instability,mode transition and re-initiation.The interaction between RDW and supply plenum may be the main reason for the fluctuations of detonation wave velocity and pressure peaks with time.Moreover,the inconsistent mixing of fuel and oxidizer at different circumferential positions is related to RDW oscillate spatially.The phenomenon of single-double-single wave transition is analyzed.During the transition,the initial RDW weakens until disappears,and the compression wave strengthens until it becomes a new RDWand propagates steadily.The increased deflagration between the detonation products and the fresh gas layer caused by excessively high temperature is one of the reasons for the RDC quenching and re-initiation.
基金support from the National Natural Science Foundation of China(No.51576027)。
文摘The convective heat transfer of supercritical-pressure RP-3(Rocket Propellant 3)aviation kerosene in a horizontal circular tube has been numerically studied,focusing mainly on the non-uniform heat transfer deterioration along the circumferential direction.The governing equations of mass,momentum and energy have been solved using the pressure-based segregated solver based on the finite volume method.The re-normalization group(RNG)k-εturbulence model with an enhanced wall treatment was selected.Considering the heat conduction in the solid wall,the mechanism of heat transfer deterioration and the buoyancy effect on deteriorated heat transfer were discussed.The evolution of secondary flow was analyzed.Effects of the outer-wall heat flux,mass flux,pressure and tube thermal conductivity on heat transfer were investigated.Moreover,the buoyancy criterion and the heat transfer correlation were obtained.Results indicate that the poor flow performance of near-wall fluid causes the pseudo-film boiling,further leads to the heat transfer deterioration.The strong buoyancy has an effect of enhancing the heat transfer at the bottom of tube,and weakening the heat transfer at the top of tube,which results in the non-uniform inner-wall temperature and heat flux distributions.Decreasing the ratio of outer-wall heat flux and mass flux,increasing the pressure could weaken the heat transfer difference along the circumferential direction,while the effect of thermal conductivity of tube on the circumferential parameters distributions is more complicated.When the buoyancy criterion of(Grq/Grth)max≤0.8 is satisfied,the effect of buoyancy could be ignored.The new correlations work well for non-uniform heat transfer predictions.
基金The authors would like to acknowledge the National Natural Science Foundation of China(Grant Nos.11802137,11702143)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX19_0292)+1 种基金the Natural Science Foundation for Young Scientists of Jiangsu Province of China(Grant No.BK20190468)the Fundamental Research Funds for the Central Universities(Grant Nos.30918011343,30919011259,309190112A1).
文摘In this paper,the kerosene/air rotating detonation engines(RDE)are numerically investigated,and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation,instabilities,and propulsive performance.A hybrid MPI t OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC)systems.A series of cases with the total pressure of 1 MPa,1.5 MPa,2 MPa,and the equivalence ratio of 0.9,1,1.4 are simulated.On one hand,the total pressure shows a significant impact on the instabilities of rotating detonation waves.The instability phenomenon is observed in cases with low total pressure(1 MPa)and weakened with the increase of the total pressure.The total pressure has a small impact on the detonation wave velocity and the specific impulse.On the other hand,the equivalence ratio shows a negligible influence on the instabilities,while it affects the ignition process and accounts for the detonation velocity deficit.It is more difficult to initiate rotating detonation waves directly in the lean fuel operation condition.Little difference was observed in the thrust with different equivalence ratios of 0.9,1,and 1.4.The highest specific impulse was obtained in the lean fuel cases,which is around 2700 s.The findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE.
基金supported by the National Natural Science Foundation of China (10672169 and 10902115)
文摘In this paper, compressible flow of aviation kerosene at supercritical conditions has been studied both numerically and experimentally. The thermophysical properties of supercritical kerosene are calculated using a 10- species surrogate based on the principle of extended corresponding states (ECS). Isentropic acceleration of supercritical kerosene to subsonic and supersonic speeds has been analyzed numerically. It has been found that the isentropic relationships of supercritical kerosene are significantly dif- ferent from those of ideal gases, A two-stage fuel heating and delivery system is used to heat the kerosene up to a tem- perature of 820 K and pressure of 5.5 MPa with a maximum mass flow rate of 100 g/s. The characteristics of supercritical kerosene flows in a converging-diverging nozzle (Laval nozzle) have been studied experimentally. The results show that stable supersonic flows of kerosene could be established in the temperature range of 730 K-820 K and the measurements in the wall pressure agree with the numerical calculation.
基金This research is supported by the Training Program of the Major Research Plan of the National Natural Science Foundation of China(Grant 91641110)the National Natural Science Foundation of China(Grant 11502270)+1 种基金the State Key Laboratory of High Temperature Gas Dynamics Innovative Foundation(Grant LHD2018JS01)The authors are grateful to the National Supercomputer Center in Tianjin for providing the computational resource.
文摘A brief review of the recent advances in kerosene-fueled supersonic combustion modeling is present by comparing the fuels,reviewing the kinetic mechanisms,and introducing recent modeling results.The advantages and disadvantages of hydrogen and kerosene for the scramjet combustor are compared to show that kerosene is a more viable fuel option for a Mach number range of 4-8.However,detailed kinetic mechanisms for kerosene,which usually contain thousands of elementary reactions,must be significantly reduced for use in modeling.As of this writing,the smallest skeletal kerosene mechanism has only 19 species and 53 reversible reactions.In contrast to pioneer models based on global chemistry,the current kerosene-fueled supersonic combustion models based on reduced/skeletal chemistry are classified as second-stage.The influence of kinetic mechanisms,global equivalence ratios,inlet Mach number,geometric shape,and domain symmetry are reviewed based on high-fidelity models and available measurements.With the advances in computational technology,models with accurate descriptions of both flow and chemistry are becoming a promising,indispensable approach for the study of supersonic combustion.
文摘In this study, kerosene fuel-rich gas produced by the combustion in the gas generator was used as the fuel and oxygen-rich air was used as the oxidant to investigate the propagation characteristics of the rotating detonation wave (RDW). The initiation of the kerosene fuel-rich gas and propagation process of the RDW were analyzed. The influences of the oxygen content in the oxidizer, kerosene mass flow rate of the gas generator, and temperature of the kerosene fuel-rich gas on the propagation process of the RDW were studied. The experimental results revealed that the propagation velocity of the RDW could be improved by increasing the three parameters mentioned above with the kerosene mass flow rate as the strongest factor. The minimum oxygen content that could successfully initiate and maintain the stable propagation of the RDW was 32%, achieving the RDW velocity of 1141.9 m/s. The RDW mainly propagated as two-counter rotating waves and a single wave when the equivalent ratios were 0.62–0.79 and 0.85–0.87, respectively. The highest RDW velocity of 1637.2 m/s was obtained when the kerosene mass flow rate, oxygen content, and equivalent ratio were 74.6 g/s, 44%, and 0.87, respectively.
基金Supported by the R&D center of Esfahan refinery (Esfahan,Iran)the technical supports of central laboratory of Esfahan Refinery for total sulfur analysis
文摘The oxidative desulfurization of a real refinery feedstock (i.e.,non-hydrotreated kerosene with total sulfur mass content of 0.16%) with a mixture of hydrogen peroxide and acetic acid was studied.The influences of various operating parameters including reaction temperature (T),acid to sulfur molar ratio (nacid/nS),and oxidant to sulfur molar ratio (nO/nS) on the sulfur removal of kerosene were investigated.The results revealed that an increase in the reaction temperature (T) and nacid/nS enhances the sulfur removal.Moreover,there is an optimum nO/nS related to the reaction temperature and the best sulfur removal could be obtained at nO/nS=8 and 23 for the reaction temperatures of 25 and 60°C,respectively.The maximum observed sulfur removal in the present oxidative desulfurization system was 83.3%.
基金Supported by National Key Technology R&D Program of China (2010BAD03B01)
文摘[Objective] The study aimed at selecting the predominant strains being able to degrade kerosene and studying its best growth conditions. [Method] Choosing kerosene as the only carbon source, we selected and separated the predominant strains being able to degrade kerosene from the contaminated soil near petrochemical plants, and then optimized the grow conditions of the bacteria. [Result] The best conditions for the bacteria growth were determined as follows, that is, temperature was 30 ℃, pH=7, salinity was 2.5%, and the rotational speed of the thermostatic shake was 190 r/min. Under the optimal conditions, the degradation rate of kerosene by the bacteria cultured for three days reached 42.6%. [Conclusion] The research could provide scientific references for the restoration of polluted soil by kerosene.
文摘Plastics wastes from a municipal solid waste (MSW) plant have a high-energy content and are suitable for fuel generation. Thermal cracking is one of the possible ways to obtain petrochemical feedstock from polymer wastes. Municipal waste plastic of LDPE conversion to kerosene grade fuel experiments were carried out under atmospheric conditions at temperatures between 150℃ and 420℃. Low density polyethylene (LDPE) plastic waste (Code #2) was thermally depolymerized in batch process into stainless steel reactor without adding catalyst. The maximum kerosene grade fuel yield is 30%, other grade fuel 60%, light gas 6% and left over residue 4%. The composition, sulphur and Btu value of liquid products were determined by ASTM method. Produced fuel was analyzed by Gas Chromatography and Mass Spectrometer and FT-IR. Very high conversions from LDPE waste plastic to kerosene grade fuel (up to 35%) were obtained while using this technique. Detailed product analyses and characterization lead to a reasonable explanation of reaction pathways and mechanisms.
基金Financial support from the National Natural Science Foundation of China (21276194)the Specialized Research Fund for the Doctoral Program of Chinese Higher Education (20101208110003)the Key Pillar Program of Tianjin Municipal Science and Technology (11ZCKGX02800)
文摘1 Introduction As the lightest metal with the unique properties of energy production and storage,lithium is regarded as the new century energy metal.Lithium and its compounds were widely used in various industrial fields,especially in
文摘Exposure to high PM10 by women and children for hours on a daily basis in poor ventilated kitchen may lead to respiratory morbidity among this vulnerable group. In Nigeria, data on the levels of air pollutants associated with kerosene stove combustion are very scarce. Like-wise little had been documented on the pulmonary health of women exposed to kerosene stove emission. This study was carried out to measure the levels of kerosene combustion emissions within kitchen environments and also assess the pulmonary function status of the exposed women at baseline. Particulate matter (PM10) and gaseous emissions (GE) were measured in six purposively selected clusters of regular kerosene stove users (KSU) using gravimetric sampler and gas monitors, respectively and their values compared with WHO guideline limits. 167 randomly selected KSU were surveyed to elicit their socio demographic features. A spirometer was used to assess the lung function status (FEV1) of 72 KSU in six neighbourhood kitchen clusters. Data were analysed using descriptive statistics, and Pearson’s correlation tests. Respondents’ mean age was 38 + 12.9 years. Mean duration of exposure to GE was 18.9 + 9.8 years. Mean PM10 was 248.1 + 14.1 μg/m3 and ten folds higher than WHO guideline limit of 25 μg/m3. Mean GE in ppm were: CO (0.00), CO2 (200.1 + 12.4), SO2 (0.01 + 0.00) and NO2 (0.00). Mean FEV1 among KSU was 2.0 + 0.5 litres which was significantly lower than the mean predicted value of 2.7 ± 0.5 litres. There was a negative correlation between PM10 and FEV1 (r = -0.7539, p > 0.05). Safer cooking methods and practices to obviate health hazards are advocated.
文摘Score-StoveTM a clean-burning cooking stove that also generates electricity was tested using a pressurized kerosene burner. The Score-Stove works on the principle of thermo-acoustics to gen- erate small-scale electricity. The device having hot-end, cold-end and regenerator acts in a way similar to a stirling cycle generating acoustic power, which is then converted to electricity using a linear actuator. It can supply small power for applications such as LED lighting, mobile phone charging and radios particularly in rural areas without grid electricity as well as improving house- hold air pollution. After assessing the needs of the rural communities through a survey, tea-stalls and small restaurants owners were identified as clients with the most potential of using the stove in Bangladesh. Bangladesh University of Engineering and Technology ((BUET) modified a Score- Stove to use both wood and a pressurized kerosene burner of a design that is widely used for cooking in rural areas of Bangladesh. The design was adapted to meet performance needs such as: heating rate, cooking efficiency, energy distribution, electric power generation, exhaust emissions and time taken to boil water using standardized water boiling tests. Performance was also compared with conventional (non-electrically generating) stoves that use a pressurized kerosene burn- er. The Score-Stove performance was then evaluated while increasing the pressure of the sealed working fluid (air in this case) from atmospheric to about 1.4 bar. The pressurization was found to almost double the power generation. An arrangement for utilizing cooling water waste heat was also devised in order to improve the thermal performance of the stove by 18%. Technical deficiencies are documented and recommendations for improvements and future research in order to obtain wider end-user acceptance are made.