Faculty Publications

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    CFD modeling and simulation of catalytic pyrolysis of heavy oils in a tapered fluidized bed reactor
    (Walter de Gruyter GmbH, 2025) Gowtham, C.; Kalathi, J.T.
    A fluidized bed reactors (FBRs) have been widely used for catlytic cracking, combustion, gasification, pyrolysis and other applications. However, to improve the performance of FBRs, a better understanding of its flow behaviour is required, especially when multiphases are present. In this research work, we have studied the hydrodynamics and performance of FBR for the catalytic pyrolysis of heavy oil into lighter fractions using a Computational Fluid Dynamics (CFD) approach. The eight-lump kinetic model was used to model the pyrolysis of heavy oil. The effect of riser geometry on the pyrolysis was investigated using a 2D transient Eulerian and the granular flow models. The fluid flow behaviour in tapered-in and tapered-out reactors (risers) for two different tapering angles (1° and 2°), conventional cylindrical reactor and pyrolysis at two different temperatures (600°C and 700°C) are studied, and the results are compared. The yield of pyrolysis products from the cylindrical riser is validated using previous mathematical models and experimental results from the literature. The results of the present CFD model for the cylindrical riser are in concert with the experimental results reported in the literature. The yields of light olefins, ethene, propene and butene are 48 wt%, 18 wt%, 34 wt%, respectively, at 700° as higher temperature favours a better yield of pyrolysis products. The same CFD model is extended to study the tapered riser geometries, and the simulation results support that the tapered-in geometry favours the pyrolysis, resulting in the higher conversion of gas oil compared to cylindrical riser due to increased residence time of solids (catalysts) and hence better contact with the fluid phase for the reactions. © 2025 Walter de Gruyter GmbH, Berlin/Boston.
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    Thermal studies of a MEMS-based pressure sensor for aerospace applications
    (John Wiley and Sons Inc, 2025) Krishna, B.G.; Murthy, K.R.; Khan, K.Z.; Madav, V.; Ashok Babu, T.P.
    The main objective of this study is to enhance heat transfer for the reduction of temperature in MEMS-based piezoresistive high-temperature pressure sensors. The main parameter that affects the sensor performance especially for Aerospace applications is higher operating temperature because there are many electronic components and devices that may fail due to higher temperatures. Prevention of overheating of the electronic components in the sensor is a challenge; hence, the study of heat transfer from hydraulic fluid is of utmost importance. Different types of fin surfaces to enhance the heat transfer rate are studied using ANSYS CFD (computational fluid dynamics). CFD simulations and experiments are carried out to design novel high operating temperature pressure sensors for aerospace applications. This in turn improves performance due to internal thermo-piezoresistive amplification. In this paper, high-temperature pressure sensors are designed by CFD analyses and experimentally analyzed for a better understanding of the distribution of temperature in the pressure sensor and thermal variation in the sensor and observe the changes during analysis. Extended fin surface concepts are introduced for better heat transfer and to reduce the fluid temperature inside the sensor that is transferred to the electronic components. ANSYS CFD analysis is carried out to determine the temperature distribution and two models are identified for experimental validation. © 2024 Wiley Periodicals LLC.