Chemical engineering education: Making connections at interfaces
Educación en ingeniería química: Haciendo conexiones en interfaces
Stephen Whitaker
Department of Chemical Engineering & Materials Science University of California at Davis. * Corresponding author. E–mail: whitaker@mcn.org
]]> Received October 21, 2008
Abstract
An interface may be a region in which concepts are connected, or it may be a region in which physical processes are connected. In both cases, conditions change abruptly. In this study, the interface between physics and chemical engineering is examined from the point of view of the laws of mechanics, and the details of this particular interface are clarified from the perspective of Euler (1703–1783) and Cauchy (1789–1857). Understanding how different perspectives of the laws of mechanics are connected allows us to proceed with confidence from physics to the traditional studies of fluid mechanics that one encounters in chemical engineering. Furthermore, it allows us to proceed with confidence to the study of multi–component transport phenomena. Here we encounter the concept of the species velocity that plays a crucial role in chemical engineering. To understand the importance of the species velocity, one asks the question: What happens if all species velocities are equal? The answer to this question is: Nothing! There is no purification, no mixing, no interfacial mass transfer, no adsorption/desorption, no homogeneous reaction, and no heterogeneous reaction. To illustrate how the concepts of mechanics provide a connection between various elements of chemical engineering, we examine the species mass jump condition as a focal point for mass transfer, heat transfer, thermodynamics, adsorption/desorption, and heterogeneous chemical reaction.
Keywords: Newton, Euler, Cauchy, multicomponent systems, phase interfaces.
Resumen
Una interface puede ser una región en la cual se conectan conceptos, o puede ser una región en la cual se conectan procesos físicos. En ambos casos, las condiciones cambian abruptamente. En este estudio, la interface entre la física y la ingeniería química es examinada desde el punto de vista de las leyes de la mecánica, y los detalles de esta interface particular son aclarados desde la perspectiva de Euler (1703–1783) y Cauchy (1789–1857). El entender cómo diferentes perspectivas de las leyes de la mecánica están conectadas nos permite proceder con confianza desde la física hasta los estudios tradicionales de mecánica de fluidos que uno encuentra en ingeniería química. Más aún, nos permite proceder con certidumbre en el estudio de fenómenos de transporte multi–componentes. Aquí encontramos el concepto de velocidad de especie que juega un papel crucial en ingeniería química. Para entender la importancia de la velocidad de especies, se hace la pregunta: ¿Qué sucede si las velocidades de todas las especies son iguales? La respuesta a esta pregunta es: ¡Nada! No hay purificación, mezclado, transferencia de masa interfacial, ni adsorción/desorción, ni reacción homogénea, y no hay reacción heterogénea. Para ilustrar como los conceptos de la mecánica proporcionan una conexión entre los diferentes elementos de la ingeniería química, examinamos la condición de salto de especies de masa como un punto focal para la transferencia de masa, transferencia de calor, termodinámica, adsorción/desorción, y reacción química heterogénea.
Palabras clave: Newton, Euler, Cauchy, sistemas multicomponentes, interfaces entre fases.
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Acknowledgment
This paper was prepared for presentation at Second International Seminar on Trends in Chemical Engineering, the XXI Century, Mexico City, January 28 – 29, 2008. The enthusiastic reception by students and faculty attending that meeting is greatly appreciated.
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