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Evaluation of oxidation stability and engine behaviors operated by Prosopis juliflora biodiesel/diesel fuel blends with presence of synthetic antioxidant

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SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS 2022年第PartA期52卷

作者： Rajamohan, Sakthivel Gopal, Abbhijith Hari Muralidharan, Karthic Raja Huang, Zuohua Paramasivam, Baranitharan Ayyasamy, Tamilvanan Nguyen, Xuan Phuong Le, Anh Tuan Hoang, Anh Tuan Amrita Vishwa Vidyapeetham Amrita Sch Engn Dept Mech Engn Coimbatore Tamil Nadu India Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Natl Inst Technol Dept Prod Engn Trichy India Kongu Engn Coll Dept Mech Engn Perundurai India Ho Chi Minh City Univ Transport PATET Res Grp Ho Chi Minh City Vietnam Hanoi Univ Sci & Technol Sch Mech Engn Hanoi Vietnam HUTECH Univ Inst Engn Ho Chi Minh City Vietnam

This experimental study focuses on analyzing the oxidation stability, engine performance, and combustion characteristics of Prosopis juliflora biodiesel blended with synthetic antioxidants. In the first stage, four synthetic antioxidants such as Butylated Hydroxy Toluene, Propyl Gallate, Pyrogallol, Tert-Butyl-Hydroquinone (TBHQ) were selected to evaluate their oxidation stability. Resultantly, TBHQ was the best synthetic antioxidant with the highest induction period, corresponding to 10.19 h, among the above-mentioned synthetic antioxidants while it was added to the B20 blend (20% Prosopis juliflora biodiesel/80% diesel fuel). In the second stage, different concentrations of TBHQ (500, 1000, and 1500 ppm) were added to B20 sample for the test of performane, combustion, and emission characteristics of a 4-stroke diesel engine. Indeed, adding TBHQ to the B20 sample increased brake thermal efficiency and emissions of CO and HC, while it reduced brake-specific fuel consumption and emissions of NOx and CO2. Furthermore, it could be observed a decrease in peaks of in-cylinder pressure and heat release rate, and an increase in mass fraction burned as adding TBHQ. In general, the use of TBHQ antioxidant-included biodiesel for diesel engines could improve engine performance and emission, and enhance the fuel' oxidation stability.

关键词： Prosopis juliflora Biodiesel Antioxidant Oxidation stability Engine behavior

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Entropy generation analysis on a heat exchanger with different design and operation factors during transient processes

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ENERGY 2018年 158卷 330-342页

作者： Wang, Chaoyang Liu, Ming Zhao, Yongliang Qiao, Yongqiang Yan, Junjie Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Entropy generation analyses on the transient processes of heat exchangers can guide their designs and operations. A dynamic model of a typical recuperative heater is developed based on mass, energy, and momentum conservation equations. Dynamic behaviors of the heater during transient processes are analyzed based on the second law of thermodynamics. The real-time entropy generation rate due to the heat transfer between the work medium and metal surfaces, and the heat conduction in metals are presented and discussed. A cold fluid flow rate with 20% step increase is adopted as the boundary disturbance, and dynamic performances are obtained. Additional entropy is generated in the heater during the transient processes compared with stationary work conditions. Several design and operation factors of the heater are discussed. Calculation results show that the additional total entropy generation diminishes during the transient processes with the increase in the thermal diffusivity of metal. This rule is also suitable for the influence of thermal transfer resistance between the fluid and metal. By contrast, the metal thickness and specific heat capacity of hot work fluid have opposite influences on the total additional entropy generation of the heater during the transient processes. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Recuperative heaters Dynamic modeling Transient processes Entropy generation

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Transient liquid leakage during plunger lifting process in gas wells

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JOURNAL OF NATURAL GAS SCIENCE AND engineering 2018年 59卷 250-261页

作者： Zhao, Kunpeng Bai, Bofeng Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Plunger lift is an economical method to solve the liquid loading problem in wells. Following our previous research (Zhao a al., 2018), which focused on the steady-state process of liquid leakage during lifting, the transient variations of plunger velocity, liquid leakage and stress conditions during plunger lifting process are investigated theoretically and experimentally in this paper. Based on the force analysis and finite difference method, the transient physical model for the mass and gas volume fraction of gas-liquid column above plunger is proposed. Combining the similarity experiments and infrared measuring technology, the proposed transient model is verified quantitatively with the relative deviation less than +/- 10%. The results show that both the liquid leakage and the gas volume fraction of gas-liquid column above plunger cannot be neglected during plunger lifting. The transient change rules of lifting differential pressure, plunger velocity, gas volume fraction of gas-liquid column and liquid leakage flow rate during lifting process are obtained. The influences of liquid loading condition and gas production rate on transient plunger lifting process are discussed. Through the dimensionless analysis, a dimensionless correlation for transient gas volume fraction of gas-liquid column is developed.

关键词： Plunger lift Transient process Liquid leakage Gas volume fraction

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Experimental study of liquid nitrogen spray characteristics in atmospheric environment

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APPLIED THERMAL engineering 2018年 142卷 717-722页

作者： Xue, Rong Ruan, Yixiao Liu, Xiufang Chen, Liang Zhang, Xingqun Hou, Yu Chen, Shuangtao Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

A comprehensive understanding of the spray characteristics at the macroscopic and microscopic levels is crucial for taking advantage of a liquid nitrogen spray. In this study, an open cycle system is developed for investigating the liquid nitrogen spray characteristics of two fine fog nozzles with different outlet diameters in an atmospheric environment. The effect of the injection pressure and nozzle orifice diameter on the mass flow rate, discharge coefficient, spray field pattern, and spray cone angle are obtained, as well as the droplet spatial distribution. The correlation between these parameters could benefit the selection of spray nozzles in a cryogenic spray cooling system.

关键词： Liquid nitrogen spray Mass flow rate Spray field Spray cone angle Droplet spatial distribution

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Numerical analysis of heat transfer to water flowing in rifled tubes at supercritical pressures

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APPLIED THERMAL engineering 2018年 133卷 704-712页

作者： Shen, Zhi Yang, Dong Li, Yaode Liang, Ziyu Wan, Li Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Heat transfer to supercritical water flowing in vertical upward rifled tubes are studied. The shear stress transport turbulence model was applied to numerical analysis and was validated with experimental data. Results of numerical simulation showed that the present model could provide a satisfactory prediction with enough accuracy. According to the results, inner wall temperature varies periodically in circumferential direction. It peaks at the intersection of the root and the leeward side and reaches the minimum at the intersection of the crest and the windward side. The circumferential distribution of inner wall heat flux is similar to that of the inner wall temperature. However, at the root the variation of inner wall heat flux is contrast to that of inner wall temperature and the rotational flow caused by the screw thread may contribute to this result. Heat transfer enhancement occurs where the boundary layer is filled with fluid of large specific heat and the effect of kinetic energy is not dominant. The structural parameters of screw thread affect heat transfer in rifled tubes. The increase of thread height significantly improved the performance of heat transfer, but the effects of pitch, lead angle and thread form are negligible.

关键词： Supercritical water Heat transfer Rifled tube Numerical simulation

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Exergy analysis of centered water nozzle steam-water injector

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EXPERIMENTAL THERMAL AND FLUID SCIENCE 2018年 94卷 77-88页

作者： Li, Wenjun Liu, Ming Yan, Junjie Wang, Jinshi Chong, Daotong Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

A steam-water injector (SI), which is a passive jet pump, has been widely used in various industries. In the present work, exergy analysis models of a centered water nozzle SI were developed based on experiments to evaluate the performance of SI. The thermodynamic perfect degree of SI was found to be not so bad, and exergy efficiency was within the range of 18%-45%. In general, SI is used to work as a pump. However, exergy analysis can only evaluate the thermodynamic perfect degree of SI, but cannot evaluate its lifting-pressure performance. Therefore, thermo-mechanical exergy was divided into temperature-based exergy and pressure-based exergy in the present work, and the pressure-based exergy analysis was introduced. Such analysis was determined to be more reasonable than exergy analysis for a passive jet pump and helpful for achieving optimal SI design. Moreover, the effects of physical and geometric parameters on exergy efficiency and pressure-based exergy efficiency were investigated experimentally, and several optimal values for these geometric parameters were found. Finally, the distributions of exergy losses in separate parts of SI, particularly inevitable exergy losses, were evaluated. These analyses will be helpful in eliminating the effects of inevitable factors and in identifying the key factor, thereby considerably improving SI performance.

关键词： Steam-water injector Exergy analysis Pressure-based exergy analysis Inevitable exergy losses

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Ignition Delay Characteristics and Kinetic Investigation of Dimethyl Ether/n-Pentane Binary Mixtures: Interpreting the Effect of the Equivalence Ratio and Dimethyl Ether Blending

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ENERGY & FUELS 2018年第3期32卷 3814-3823页

作者： Jiang, Xue Deng, Fuquan Yang, Feiyu Huang, Zuohua Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Measurements of the autoignition delays of dimethyl ether (DME)-enriched n-pentane mixtures were conducted at the equivalence ratios of 0.5-2.0, pressure of 20 atm, and temperatures of 1100-1600 K using a shock tube, and new data were provided for dual-fuel engine design, kinetic model development, and computational simulation. A recently published pentane isomer model was validated and used for kinetic analysis. It is found that the autoignition delay of n-pentane becomes longer as the equivalence ratio (fuel/air) increases. However, for DME, the dependence upon the equivalence ratio is inverse to that of n-pentane. Autoignition delays of DME/n-pentane mixtures become shorter with the increased DME proportion, except for the phi = 0.5 conditions, where the autoignition delays of DME and n-pentane are identical.

关键词： Hydrocarbons Addition reactions Mixtures Fuels Reactivity

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Experimental investigation on heat transfer characteristics in circulatory flash vaporization of aqueous NaCl solution

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DESALINATION 2018年 446卷 12-20页

作者： Wang, Yu He, Qi Li, Gen Yang, Qingzhong Yan, Junjie Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

In this work, a series of experiments on circulatory flash vaporization of 10% and 20% NaCl solution was performed. The heat transfer characteristics in circulatory flash vaporization under different experimental conditions were presented. The non-equilibrium fraction of circulatory flash vaporization (NEF) was adopted to describe the extent of flash vaporization process completion. A volumetric heat transfer coefficient of circulatory flash vaporization (h(v)) was introduced in the present study to evaluate the heat flux evolution from per unit volume of liquid pool under unit superheat degree. Moreover, the influences of superheat degree, pressure of flash evaporator, initial liquid level, circulating flow rate and concentration of NaCl solution on the volumetric heat transfer coefficient were also analyzed. Results suggested that the volumetric heat transfer coefficient increased with the superheat degree and flash chamber pressure. Lowering the initial liquid level and brine concentration promoted the heat transfer intensity. And Nusselt number of circulatory flash vaporization Nu(A) was proposed to describe the heat transfer performance of circulatory flash vaporization according to the definition of volumetric heat transfer coefficient. Moreover, a correlation between Nusselt number of circulatory flash vaporization and dimensionless parameters was obtained with the relative error between -31.1% and 32.8% for 1.5 <= Delta T <= 20 K, 400 <= Q <= 1200 L h(-1), 7.4 <= P-f <= 31.2 kPa and 0.05 <= f(m) <= 0.2.

关键词： Circulatory flash vaporization Volumetric heat transfer coefficient Non-equilibrium fraction Aqueous NaCl solution

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Experimental Measurement of JP-10 Density at 267 to 873 K under Pressures up to 6.00 MPa

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JOURNAL OF CHEMICAL AND engineering DATA 2019年第1期64卷 218-225页

作者： Qin, Zhizhen Gong, Siyuan Zhang, Xiangwen Bi, Qincheng Liu, Zhaohui Liu, Guozhu Tianjin Univ Key Lab Green Chem Technol Minist Educ Sch Chem Engn & Technol Tianjin 300072 Peoples R China Tianjin Univ Collaborat Innovat Ctr Chem Sci & Engn Tianjin Tianjin 300072 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shanxi Peoples R China

Density is one of the most important thermophysical properties of aviation fuel for the advanced fuel-cooled thermal management. The density of a hydrocarbon fuel JP-10 was measured using a gamma-ray radial method calibrated with deionized water, cyclohexane, and a mixture of n-heptane and n-octane. The average absolute deviation (AAD) of deionized water is 0.22% under 3.0 MPa and 0.43% under 5.0 MPa, that of cyclohexane is 0.80% under 5.0 MPa, and that of the mixture of n-heptane and n-octane is 0.33% under 5.1 MPa. The experimental density of JP-10 was reported at 267 to 873 K under the pressure of 0.70 to 6.00 MPa. Two empirical correlations were used to fit the liquid and gas density data separately. The results are that the AAD for all the liquid data is 0.46%, and that for all the gas data is 6.12%. Finally, the isobaric thermal expansion was calculated.

关键词： Thermal expansion Liquids Supercritical fluids Theoretical and computational chemistry Gases

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Experimental investigation on thermo-acoustic instability and heat transfer of supercritical endothermic hydrocarbon fuel in a mini tube

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EXPERIMENTAL THERMAL AND FLUID SCIENCE 2018年 97卷 109-118页

作者： Pan, Hui Bi, Qincheng Liu, Zhaohui Feng, Song Feng, Fan Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

The thermo-acoustic instability and heat transfer coefficients of a kerosene kind endothermic hydrocarbon fuel were experimentally investigated in a horizontal mini tube at supercritical pressure. The test section was a 316 stainless steel tube with a length of 240 mm and an inner diameter of 1.60 mm. Experiments were conducted at pressures of 2.5-4.0 MPa, mass fluxes of 800-1200 kg/m(2)-s, and heat fluxes of 665-950 kW/m(2). The relative standard deviation (RSD) of pressure drop was used to evaluate the intensity of thermo-acoustic instability. The correlation between heat transfer coefficient and the oscillation intensity was discussed. The results indicate that the periodic decrease in wall temperature is accompanied by synchronous increases in the outlet bulk temperature and pressure drop during oscillation. Thermo-acoustic oscillation is more pronounced at lower mass flux, lower pressure, or higher heat flux. The instability disappears when the inlet bulk temperature exceeds a threshold value. In the oscillation region, the heat transfer coefficient is positively correlated with the oscillation intensity. Heat transfer deterioration will occur at the stable boundary between the oscillation region and the stable region. A dimensionless criterion is obtained to evaluate the stable boundary of thermal-acoustic oscillation.

关键词： Hydrocarbon fuel Heat transfer Thermo-acoustic instability Stable boundary

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