Kinetics Parameters Evaluation of Paraffin-Based Fuel

2012 ◽  
Author(s):  
Genivaldo P. Santos ◽  
Pedro T. Lacava ◽  
Susane R. Gomes ◽  
José Atíllio F. F. Rocco
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Thermo Gravimetric Analysis ◽  
Kinetic Mechanism ◽  
Gravimetric Analysis ◽  
Propulsion Systems ◽  
Kinetics Parameters ◽  
Gaseous Oxygen ◽  
Exponential Factor ◽  
Hybrid Propulsion

In recent years, Hybrid Propulsion is turning into a significant alternative to Liquid and Solid Propulsion Systems, it presents attractive features and good balance between performance and environmental impact. Thus, paraffin based propellant grains are indicated as a substitute for hydroxyl-terminated polybutadiene (HTPB), the actual solid propellant fuel grain. Despite being a well-known material, scarce data on the relation of activation energy (Ea) and molecular weight (WCxHy) of paraffin is available. In this work, the kinetic parameters (activation energy and pre-exponential factor) of microcrystalline 140/145°F paraffin have been raised through Thermo Gravimetric Analysis in conjunction with the Arrhenius kinetic mechanism, according to ASTM-E1461 and the dependence of molecular weight with melting point from Etessam and Sawyer approach. The 140/145°F paraffin activation energy calculated in this study was compared with different activation energy from alkanes and substances used as fuel in the propulsion systems field. The analysis indicated that the microcrystalline 140/145°F paraffin, manufactured by Petrobras, presents activation energy of 224 KJ.mol−1 and pre-exponential factor of 5.48×1022 min−1. Ignition was achieved with a 50 W pyrotechnic igniter. The firing test with 140/145°F paraffin fuel and gaseous oxygen (GOX) mass flux of 130 Kg.s−1 m−2 at pressure above 0.80 MPa, was easily sustained.

Thermo-Gravimetric Analysis and Kinetic Study of Biomass Pyrolysis

2013 ◽  
Vol 800 ◽  
pp. 509-516 ◽  
Author(s):  
Yong Sheng Fan ◽  
Xiao Hua Li ◽  
Yi Xi Cai ◽  
Wei Dong Zhao ◽  
Hai Yun Yin
Keyword(s):  
Activation Energy ◽  
Heating Rate ◽  
Thermo Gravimetric Analysis ◽  
Evaluation Methodology ◽  
Gravimetric Analysis ◽  
Pyrolysis Process ◽  
Biomass Pyrolysis ◽  
Thermo Gravimetric ◽  
Exponential Factor ◽  
Kinetics Of

In order to realize the optimization of pyrolysis process, the pyrolysis characteristics and kinetics of common agriculture and forestry biomass were studied. Four kinds of biomass were chosen as experiment materials for thermo-gravimetric experiment. The Characteristics of biomass pyrolysis was studied by defining a new evaluation methodology. The method of Coats-Redfern was used to analyze pyrolysis kinetics of biomass pyrolysis process. The results of research show that the pyrolysis process of biomass can be divided into three stages, including drying and preheating, fast pyrolysis and slow decomposition of residue. The activation energy of pyrolysis reaction of biomass during the low temperature stage is higher than that of the high temperature stage. The values of the activation energy and pre-exponential factor are increasing with the increase of heating rate. The pyrolysis of biomass in the main pyrolysis zone can be effectively described by using the kinetic model n=2. The heating rate of 15K/min and temperature of 500°C can improve the reaction rate, and it helps to reduce energy consumption of the reaction.

Isotope Exchange of Gaseous Oxygen with Oxide LaMno3+δ Nanograins Boundary

2010 ◽  
Vol 297-301 ◽  
pp. 1301-1305
Author(s):  
Anatoly Yakovlevich Fishman ◽  
Tatiana Eugenievna Kurennykh ◽  
Vladimir Borisovich Vykhodets ◽  
V.B. Vykhodets
Keyword(s):  
Activation Energy ◽  
Exchange Rate ◽  
Isotope Exchange ◽  
Shock Wave Loading ◽  
Wave Loading ◽  
Gaseous Oxygen ◽  
Exponential Factor ◽  
Significant Difference ◽  
Exponential Factors ◽  
Arrhenius Expression

Isotope exchange of oxygen 18О2 with the boundary of nanograins of oxide LaMnO3+ obtained by the method of shock-wave loading was investigated in the temperature range of 400 – 500 °C. It was established that the temperature dependence of the isotope exchange rate is described by the Arrhenius expression, the activation energy and the pre-exponential factor being 1.67 eV and 1.8∙102 cm/s, respectively. Comparison with literature data has shown that for oxide LaMnO3+, a significant difference in activation energies and pre-exponential factors is observed for the isotope exchange rate with a ‘defect-free’ surface and the nanograin boundary. In case of the boundary, these parameters were higher: the activation energy about two times, and the pre-exponential factor, by almost 7 orders of magnitude.

scholarly journals THE KINETICS OF CaO ASSISTED PATTUKKU CHARCOAL STEAM GASIFICATION

REAKTOR ◽  
2018 ◽  
Vol 18 (1) ◽  
pp. 16
Author(s):  
Takdir Syarif ◽  
H Sulistyo ◽  
Wahyudi B Sediawan ◽  
B Budhijanto
Keyword(s):  
Activation Energy ◽  
Tubular Reactor ◽  
Steam Gasification ◽  
Effect Of Temperature ◽  
Composition Analysis ◽  
Zone Model ◽  
Kinetics Parameters ◽  
Exponential Factor ◽  
Surface Diffusivity ◽  
Gasification Process

Abstract Coal is a solid fuel that can be converted into syngas through gasification process. To obtain optimum gasification process design and operation, in-depth understanding of the influential parameters is required. This study aims to investigate the effect of temperature on the gasification process and to obtain its kinetics parameters. The study was carried out in a tubular reactor equipped with a heater and a condenser. Steam was used as gasifying agent, while CaO was employed as a CO2 adsorbent. The charcoal from coal was subjected to gasification at temperatures of 600°C, 700°C, and 800°C. The ratio of charcoal and CaO was 1:1. The gasification process lasted for 60 minutes with gas sample was taken every 15 minutes for composition analysis. The results showed that a temperature increase of 100°C caused a proportional increase of conversion of about 75% higher. The value of activation energy (Ea) and exponential factor (ko) were 46.645kJ/mole and 328.3894/min, respectively. For mass transfer parameters, values of activation energy for surface diffusion (Es) and surface diffusivity factor (as) were 81.126 kJ/mole and 0.138/min, respectively. Keywords: gasification; mathematical model; Pattukku coal char; steam; Thin Reaction Zone Model

scholarly journals Thermal decomposition characteristics of foundry sand for cast iron in nitrogen atmosphere

2018 ◽  
Vol 5 (12) ◽  
pp. 181091 ◽  
Author(s):  
Qingwei Xu ◽  
Kaili Xu ◽  
Xiwen Yao ◽  
Jishuo Li ◽  
Li Li
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Cast Iron ◽  
Low Cost ◽  
Temperature Stability ◽  
Nitrogen Atmosphere ◽  
High Temperature Stability ◽  
Kinetics Parameters ◽  
Foundry Sand ◽  
Exponential Factor

Sand casting, currently the most popular approach to the casting production, has wide adaptability and low cost. The thermal decomposition characteristics of foundry sand for cast iron were determined for the first time in this study. Thermogravimetry was monitored by simultaneous thermal analyser to find that there was no obvious oxidation or combustion reaction in the foundry sand; the thermal decomposition degree increased as the heating rate increased. There was an obvious endothermic peak at about 846 K due to the transition of quartz from β to α phase. A novel technique was established to calculate the starting temperature of volatile emission in determining the volatile release parameter of foundry sand for cast iron. Foundry sand does not readily evaporate because its volatile content is only about 2.68 wt% and its main components have high-temperature stability. The thermal decomposition kinetics parameters of foundry sand, namely activation energy and pre-exponential factor, were obtained under kinetics theory. The activation energy of foundry sand for cast iron was small, mainly due to the wide temperature range of thermal decomposition in the foundry sand.

scholarly journals CO2 Gasification Kinetics of Shenhua Bituminous Coal by Isothermal Thermo-Gravimetric Analysis

2020 ◽  
Author(s):  
Jinzhi Zhang ◽  
Zhiqi Wang ◽  
Ruidong Zhao ◽  
Jinhu Wu
Keyword(s):  
Activation Energy ◽  
Bituminous Coal ◽  
Thermo Gravimetric Analysis ◽  
Correlation Coefficients ◽  
Mathematical Expression ◽  
Frequency Factor ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Kinetics Of ◽  
Compensation Relationship

Abstract This research performed the gasification kinetics of three Shenhua coal under CO2 atmosphere using isothermal thermogravimetry. Results showed that isothermal gasification curves for three different coal samples revealed different gasification behaviour. Among the eleven kinetic models, A2 was the most suitable one to describe the gasification kinetics of three coal samples, because it can reproduce the experimental data very well with reasonable correlation coefficients. The activation energy for sample A, B and C were 95.9, 79.1, and 69.4 kJ mol-1, respectively. The activation energy decreased with the increase of the particle size. The compensation relationship was observed between activation energy and frequency factor, and the mathematical expression was lnA=0.1041 E+0.54028 with the correlation coefficients of 0.999.

scholarly journals Non-isothermal decomposition kinetics of magnesite

Cerâmica ◽  
2007 ◽  
Vol 53 (327) ◽  
pp. 284-287 ◽  
Author(s):  
S. Maitra ◽  
S. Mukherjee ◽  
N. Saha ◽  
J. Pramanik
Keyword(s):  
Kinetic Parameters ◽  
Thermo Gravimetric Analysis ◽  
Isothermal Condition ◽  
Kinetic Mechanism ◽  
Decomposition Reaction ◽  
Magnesium Carbonate ◽  
Decomposition Kinetics ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Kinetics Of

Kinetics of thermal decomposition of Indian magnesite was studied by thermo-gravimetric analysis under non-isothermal condition. Coats and Redfern Integral approximation method was used to determine the kinetic parameters. Using the kinetic parameters different kinetic functions were analyzed with the experimental data to ascertain the decomposition mechanism of magnesium carbonate and it was observed that the decomposition reaction followed a contracting sphere kinetic mechanism.

scholarly journals Nytrox as “Drop-in” Replacement for Gaseous Oxygen in SmallSat Hybrid Propulsion Systems

Aerospace ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 43 ◽  
Author(s):  
Stephen A. Whitmore
Keyword(s):  
Specific Impulse ◽  
Acrylonitrile Butadiene Styrene ◽  
N2o Decomposition ◽  
Combustion Efficiency ◽  
Future Research ◽  
Propulsion Systems ◽  
Gaseous Oxygen ◽  
Thrust Coefficient ◽  
Hybrid Propulsion ◽  
Dissolved Carbon

A medical grade nitrous oxide (N2O) and gaseous oxygen (GOX) “Nytrox” blend is investigated as a volumetrically-efficient replacement for GOX in SmallSat-scale hybrid propulsion systems. Combined with 3-D printed acrylonitrile butadiene styrene (ABS), the propellants represent a significantly safer, but superior performing, alternative to environmentally-unsustainable spacecraft propellants like hydrazine. In a manner analogous to the creation of soda-water using dissolved carbon dioxide, Nytrox is created by bubbling GOX under pressure into N2O until the solution reaches saturation. Oxygen in the ullage dilutes N2O vapor and increases the required decomposition energy barrier by several orders of magnitude. Thus, risks associated with inadvertent thermal or catalytic N2O decomposition are virtually eliminated. Preliminary results of a test-and-evaluation campaign are reported. A small spacecraft thruster is first tested using gaseous oxygen and 3-D printed ABS as the baseline propellants. Tests were then repeated using Nytrox as a “drop-in” replacement for GOX. Parameters compared include ignition reliability, latency, initiation energy, thrust coefficient, characteristic velocity, specific impulse, combustion efficiency, and fuel regression rate. Tests demonstrate Nytrox as an effective replacement for GOX, exhibiting a slightly reduced specific impulse, but with significantly higher volumetric efficiency. Vacuum specific impulse exceeding 300 s is reported. Future research topics are recommended.

Activation Energy of Decomposition of Y2bacuo5 Compound in Wet Co2 at Elevated Temperatures

1989 ◽  
Vol 169 ◽  
Author(s):  
John J. Simmins ◽  
Michael J. Hanagan ◽  
Gary S. Fischman ◽  
Robert L. Snyder
Keyword(s):  
Activation Energy ◽  
Elevated Temperatures ◽  
Barium Carbonate ◽  
Thermo Gravimetric Analysis ◽  
Time Derivative ◽  
Simultaneous Thermal Analysis ◽  
Analysis Data ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Thermo Gravimetric

AbstractDecomposition of the Y2BaCuO5 in C02 was studied using simultaneous thermal analysis (STA) and X-ray diffraction (XRD). The time derivative to the thermo-gravimetric analysis data (DTG) was used to calculate the activation energy. The activation energy of decomposition by CO2 into barium carbonate, copper oxide and yttrium oxide was found to be <

The Research on the Relationship between the Coal Volatile and the Kinetics Parameters by Thermo-Gravimetric Experiment

2012 ◽  
Vol 512-515 ◽  
pp. 1813-1818
Author(s):  
Li Na Qu ◽  
Yuan Gang Jiang ◽  
Ru Le Gao
Keyword(s):  
Activation Energy ◽  
Coal Combustion ◽  
Spontaneous Combustion ◽  
Volatile Matter ◽  
Coal Spontaneous Combustion ◽  
Thermo Gravimetric ◽  
Kinetics Parameters ◽  
Exponential Factor ◽  
Internal Mechanism ◽  
The Relationship

Coal spontaneous combustion is a common coal mine disaster, the internal mechanism of coal combustion is revealed better by researched the relationship between the coal volatile and the kinetics parameters. Based on the method of non-isothermal, the coal samples from Jinggezhuang9#, Jinggezhuang11#, Qianjiaying, Tangshan and Tunlan are used the thermo-gravimetric experiment. The relationship between the reactive kinetic parameter and the volatile matter are fond out, when the heating rate is 100C/min. The experiment results illustrate that the more the volatile matter is, the less the activation energy (E) and the Pre Exponential factor (A) are, and the difficulty rank of coal samples of spontaneous combustion is Jinggezhuang9#, Jinggezhuang11#, Tangshan, Qianjiaying, Tunlan.

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