Significance of dimensionless numbers in heat transfer pdf

In this respect, the nature of the flow and the interaction of the phases has a significant. It is the ratio of the thermal energy convected to the fluid to the thermal energy conducted within the fluid. Dimensionless numbers in fluid mechanics wikipedia. Important dimensionless numbers and their significance free download as word doc. Froude number of a flowing fluid is also a dimensionless number which is basically defined as the square root of ratio of the inertia force to gravity force and it is used in engineering applications in order to express the influence of gravity over motion of fluid. On the physical significance of some dimensionless numbers used in heat transfer and fluid flow clovis r. Important dimensionless numbers and their significance fluid. Nondimensional scaling provides a method for developing dimensionless groups that can. Dimensionless numbers reduce the number of variables that describe a system, thereby reducing the.

If lewis number is greater than one item explains the predominance of concentration boundary layer. Dimensionless numbers in heat transfer me mechanical. This is used to characterize flows in which there is simultaneous heat and mass by convection transfer. Reynolds number, gives the information, whether the flow is inertial or viscous force dominant. The reynolds number is used to determine whether flow is laminar or turbulent. Explanation and analysis of dimensionless numbers in heat transfer and their significance in thermal management. It is almost impossible to read an article or listen to a lecture on heat transfer without hearing names like reynolds.

The nusselt number characterizes the similarity of heat transfer at the interface between wall and fluid in different systems. Dimensionless numbers reduce the number of variables that describe a system, thereby reducing the amount of experimental data required to make correlations of physical phenomena to scalable systems. Dimensionless numbers in fluid mechanics are a set of dimensionless quantities that have. Why are dimensionless numbers used in heat transfer and. It tells us whether the flow is laminar or turbulent. Those names are given here because some people use them, and youll probably hear them at some point in your career. Fatoyinbo, in microfluidic devices for biomedical applications, 20. The relevance and use of these numbers follow from their. Heat and mass transfer, flow regimes, crossflow, liquid sheet. Different dimensionless numbers used for heat transfer and mass transfer.

Nusselt number is basically a ratio of convective heat transfer coefficient to conductance. List of all important dimensionless numbers and their significance. Lewis number is a dimensionless number which is the ratio of thermal diffusivity to mass diffusivity or schmidt number to prandtl number. This number is important in cases when a large velocity change occurs over short distances such as lubricant, supersonic flow in rocket mechanics creating large heat effect in the head due to large velocity in many place it is a combination of eckert number with brinkman number. Dimensionless numbers are of very high importance in mechanical engineering and chemical engineering including thermodynamics, fluid mechanics, mass transfer, heat transfer, solid mechanics, momentum transfer and chemical reaction engineering. The tran sient conduction inside the particles is ratecontrolling. These nondimensional numbers are helpful tools in heat transfer. The most common dimensionless group in fluid dynamics is the reynolds number re, named. Dimensionless number an overview sciencedirect topics. The significance of the marangoni number is that its large. The peclet number is a dimensionless number used in calculations involving convective heat transfer.

If pe is small, conduction is important and in such a case, the major source of conduction could be down the walls of a tube. Dimensionless numbers are of very high importance in mechanical. Brinkman number measures of the importance of the viscous heating relative the conductive heat transfer. Characterising the heat and mass transfer coefficients for a. List of all important dimensionless numbers and their.