The 3-D Image of The Temperature Integral And Its Self-Similarity

How to derive the accurate value of temperature integral is a vital problem for the non-isothermal kinetic analysis. In the past six decades, researchers provided various methods to solve above problem, but the error usually becomes divergent when the value of x (x=Ea/RT) is too small or too large, no matter whether it is a numerical method or an approximation method. In this paper, we present a new series method and elaborately design a computer program to calculate the value of temperature integral. Finally, we reveal the mysterious relationship between the integral, the temperature and the activation energy, and we find an extremely interesting phenomenon that the 3-D image of the temperature integral is of self-similarity according to the fractal theory.

Pyrolysis Kinetic Parameters of Omari Oil Shale Using Thermogravimetric Analysis

Oil shale is one of the alternative energies and fuel solutions in Jordan because of the scarcity of conventional sources, such as petroleum, coal, and gas. Oil from oil shale reservoirs can be produced commercially by pyrolysis technology. To optimize the process, mechanisms and rates of reactions need to be investigated. Omari oil shale formation in Jordan was selected as a case study, for which no kinetic models are available in the literature. Oil shale was analyzed using the Fischer assay method, proximate analysis (moisture, volatile, and ash), gross calorific value, elemental analysis (CHNS), and X-ray fluorescence (XRF) measurements. Non-isothermal thermogravimetric analysis was applied to study the kinetic parameters (activation energy and frequency factor) at four selected heating rates (5, 10, 15, and 20 °C/min). When oil shale was heated from room temperature to 1100 °C, the weight loss profile exhibited three different zones: drying (devolatilization), pyrolysis, and mineral decomposition. For each zone, the kinetic parameters were calculated using three selected methods: integral, temperature integral approximation, and direct Arrhenius plot. Furthermore, the activation energy in the pyrolysis zone was 112–116 kJ/mol, while the frequency factor was 2.0 × 107 − 1.5 × 109 min−1. Moreover, the heating rate has a directly proportional relationship with the rate constant at each zone. The three different methods gave comparable results for the kinetic parameters with a higher coefficient of determination (R2) for the integral and temperature integral approximation compared with the direct Arrhenius plot. The determined kinetic parameters for Omari formation can be employed in developing pyrolysis reactor models.

Investigation of the effective parameters of scuffing failure in gears

This study investigates the effective parameters of scuffing failure in gears using the integral temperature method. For this aim, the mass temperature, integral temperature and scuffing safety factor are calculated for a given parameters. Then, integral temperatures are simulated based on various geometrical, operational and lubrication parameters. Obtained results are presented graphically. The obtained results show that increasing the module mn results in a decrease in the integral temperature ϑint. Similarly, increasing the pinion teeth number zp results in a decrease in the integral temperature ϑint. Increasing the module and tooth number positively affects the scuffing failure in gears. In contrast, increasing the transmitted torque MT1T results in an increase in the integral temperature ϑint. Similarly, increasing the pinion speed np increases the mass temperature ϑM, and increasing the lubricant (oil) ϑÖ temperature increases the integral temperature ϑint. Increasing the transmitted torque, lubricant temperature and the pinion speed negatively affects the scuffing failure in gears. Finally, increasing the nominal kinematic viscosity v40 decreases the integral temperature ϑint. Increasing the nominal kinematic viscosity positively affects the scuffing failure in gears. By considering the effective parameters of scuffing failure such as geometrical, operational and lubrication, one can design and manufacture the desired gears without scuffing failure.