Stirring Rate
Stirring Rate - Related Videos
10:20
Mammalian Cell Encapsulation in Alginate Beads Using a Simple Stirred Vessel
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Cited by 13 •
2017
This video and manuscript describe an emulsion-based method to encapsulate mammalian cells in 0.5% to 10% alginate beads which can be produced in large batches using a simple stirred vessel. The encapsulated cells can be cultured in vitro or transplanted for cellular therapy applications.
10:49
Power Input Measurements in Stirred Bioreactors at Laboratory Scale
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Cited by 9 •
2018
The power input in stirred bioreactors can be measured through the torque that acts on the impeller shaft during rotation. This manuscript describes how an air bearing can be used to effectively reduce friction losses observed in mechanical seals and improve the accuracy of power input measurements in small-scale vessels.
11:31
Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation
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Cited by 34 •
2012
Laboratory-scale anaerobic digesters allow scientists to research new ways of optimizing existing applications of anaerobic biotechnology and to evaluate the methane producing potential of various organic wastes. This article introduces a generalized model for the construction, inoculation, operation, and monitoring of a laboratory-scale continuously stirred anaerobic digester.
02:53
Reaction Rate
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2020
The rate of reaction is the change in the amount of a reactant or product per unit time. Reaction rates are therefore determined by measuring the time dependence of some property that can be related to reactant or product amounts. Rates of reactions that consume or produce gaseous substances, for example, are conveniently determined by measuring changes in volume or pressure. The mathematical representation of the change in the concentration of reactants and products, over time, is the rate...
01:18
Related Rates
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2026
When two or more physical quantities are linked by a single relationship, a change in one variable necessarily affects the others. This interdependence forms the basis of related rates analysis, which examines how different quantities change with respect to time. A classic physical example is an expanding balloon, where the size of the balloon changes continuously as air is added.For a hot air balloon, the inflated envelope is commonly idealized as a perfect sphere to simplify mathematical...
FAQs
These factors determine how effectively agitation moves the mixture. Higher viscosity can make uniform circulation more difficult, while vessel geometry and impeller design influence the flow pattern produced at a given speed. Consequently, the same stirring rate may mix one formulation effectively but leave another poorly blended, so rate selection must account for the complete vessel and mixture configuration.
Increasing agitation is not always beneficial. Excessive stirring can introduce air bubbles into the mixture or disrupt materials that are sensitive to strong fluid motion. These effects may alter the physical state of the sample and make reaction conditions less consistent. A suitable rate therefore balances improved mixing and transfer with the need to avoid unnecessary mechanical disturbance.
Agitation can maintain suspended particles in the mixture by counteracting their tendency to settle. This helps preserve a more uniform distribution of solids and supports consistent contact between particles and the surrounding liquid. If the rate is too low, settling may reduce uniformity; if it is unnecessarily high, the resulting fluid motion may disturb sensitive components or introduce bubbles.
Faster fluid motion generally improves the movement of heat and chemical species through a mixture. Better mass transfer helps reactants contact one another, while improved heat transfer supports more uniform temperature conditions throughout the vessel. These effects can promote consistent reaction behavior, but the selected rate still needs to suit the mixture rather than simply being increased without limit.
Begin by considering the mixture's viscosity, whether particles must remain suspended, the vessel geometry, and the impeller design. Then choose a rate that provides uniform mixing and adequate heat or mass transfer without producing excessive bubbles or disrupting sensitive materials. This approach helps maintain consistent conditions across runs and improves the reproducibility of the resulting chemical process.
Controlled agitation supports several distinct operations, including dissolution, precipitation, crystallization, extraction, and synthesis. In each case, the rate helps determine how uniformly components contact one another and how consistently the mixture behaves throughout processing. Matching agitation to the process can improve uniformity and reproducibility, while inappropriate stirring may promote settling, uneven conditions, or unwanted physical disturbance.