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Chemical engineering is a certain type of engineering which deals with the study of operation and design of chemical plants as well as methods of improving production. Chemical engineers develop economical commercial processes to convert raw material into useful products. Chemical engineering uses principles of chemistry, physics, mathematics, biology, and economics to efficiently use, produce, design, transport and transform energy and materials. The work of chemical engineers can range from the utilization of nanotechnology and nanomaterials in the laboratory to large-scale industrial processes that convert chemicals, raw materials, living cells, microorganisms, and energy into useful forms and products. Chemical engineers are involved in many aspects of plant design and operation, including safety and hazard assessments, process design and analysis, modeling, control engineering, chemical reaction engineering, nuclear engineering, biological engineering, construction specification, and operating instructions.
Molecular diffusion, often simply called diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size (mass) of the particles. Diffusion explains the net flux of molecules from a region of higher concentration to one of lower concentration. Once the concentrations are equal the molecules continue to move, but since there is no concentration gradient the process of molecular diffusion has ceased and is instead governed by the process of self-diffusion, originating from the random motion of the molecules. The result of diffusion is a gradual mixing of material such that the distribution of molecules is uniform. Since the molecules are still in motion, but an equilibrium has been established, the end result of molecular diffusion is called a "dynamic equilibrium". In a phase with uniform temperature, absent external net forces acting on the particles, the diffusion process will eventually result in complete mixing.
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics and hydrodynamics. Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation.
In fluid dynamics, laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mixing, and adjacent layers slide past one another like playing cards. There are no cross-currents perpendicular to the direction of flow, nor eddies or swirls of fluids. In laminar flow, the motion of the particles of the fluid is very orderly with particles close to a solid surface moving in straight lines parallel to that surface. Laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection.
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In fluid mechanics, a shell balance can be used to determine how fluid velocity changes across a flow.
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The Reynolds number helps predict flow patterns in different fluid flow situations. At low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers flows tend to be turbulent. The turbulence results from differences in the fluid's speed and direction, which may sometimes intersect or even move counter to the overall direction of the flow. These eddy currents begin to churn the flow, using up energy in the process, which for liquids increases the chances of cavitation. Reynolds numbers are an important dimensionless quantity in fluid mechanics.
Edwin Niblock Lightfoot Jr. was an American chemical engineer and Hilldale Professor Emeritus in the Department of Chemical and Biological Engineering at the University of Wisconsin-Madison. He is known for his research in transport phenomena, including biological mass-transfer processes, mass-transport reaction modeling, and separations processes. He, along with R. Byron Bird and Warren E. Stewart, co-authored the classic textbook Transport Phenomena. In 1974 Lightfoot wrote Transport Phenomena and Living Systems: Biomedical Aspects of Momentum and Mass Transport. Lightfoot was the recipient of the 2004 National Medal of Science in Engineering Sciences.
In engineering, physics and chemistry, the study of transport phenomena concerns the exchange of mass, energy, charge, momentum and angular momentum between observed and studied systems. While it draws from fields as diverse as continuum mechanics and thermodynamics, it places a heavy emphasis on the commonalities between the topics covered. Mass, momentum, and heat transport all share a very similar mathematical framework, and the parallels between them are exploited in the study of transport phenomena to draw deep mathematical connections that often provide very useful tools in the analysis of one field that are directly derived from the others.
Particle-laden flows refers to a class of two-phase fluid flow, in which one of the phases is continuously connected and the other phase is made up of small, immiscible, and typically dilute particles. Fine aerosol particles in air is an example of a particle-laden flow; the aerosols are the dispersed phase, and the air is the carrier phase.
Combustion models for CFD refers to combustion models for computational fluid dynamics. Combustion is defined as a chemical reaction in which a hydrocarbon fuel reacts with an oxidant to form products, accompanied with the release of energy in the form of heat. Being the integral part of various engineering applications like: internal combustion engines, aircraft engines, rocket engines, furnaces, and power station combustors, combustion manifests itself as a wide domain during the design, analysis and performance characteristics stages of the above-mentioned applications. With the added complexity of chemical kinetics and achieving reacting flow mixture environment, proper modeling physics has to be incorporated during computational fluid dynamic (CFD) simulations of combustion. Hence the following discussion presents a general outline of the various adequate models incorporated with the Computational fluid dynamic code to model the process of combustion.
The flow in manifolds is extensively encountered in many industrial processes when it is necessary to distribute a large fluid stream into several parallel streams and then to collect them into one discharge stream, such as fuel cells, plate heat exchanger, radial flow reactor, and irrigation. Manifolds can usually be categorized into one of the following types: dividing, combining, Z-type and U-type manifolds. A key question is the uniformity of the flow distribution and pressure drop.
References
- ↑ This Week's Citation Classic (University of Pennsylvania, Garfield Library)
- ↑ Bird, R.B., Stewart, W.E. and Lightfoot, E.N. (1958). Notes on transport phenomena. John Wiley & Sons. LCCN 58010796. OCLC 5123255.CS1 maint: multiple names: authors list (link)
- ↑ Bird, R.B., Stewart, W.E. and Lightfoot, E.N. (August 2001). Transport Phenomena (Second ed.). John Wiley & Sons. ISBN 0-471-41077-2.CS1 maint: multiple names: authors list (link)
- ↑ Bird, R.B., Stewart, W.E. and Lightfoot, E.N. (2007). Transport Phenomena (Revised Second ed.). John Wiley & Sons. ISBN 978-0-470-11539-8.CS1 maint: multiple names: authors list (link)
- ↑ Bird, Stewart, Lightfoot Programs Archived 2004-05-17 at archive.today
- ↑ Bird, Stewart, Lightfoot Programs Archived 2004-05-17 at archive.today
- ↑ Transport Phenomena: A Landmark in Chemical Engineering Education Archived 2015-09-09 at the Wayback Machine
- ↑ Notes for the 2nd revised edition of TRANSPORT PHENOMENA
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