Heat transfer analogies with other processes

Steady-state heat transfer Unsteady-state heat transfer Convective heat transfer (heat transfer coefficient) Convective heat transfer (heat transfer coefficient) Radiative heat transfer (not analogous with other transfer processes) Steady-state molecular diffusion Unsteady-state molecular diffusion Convective mass transfer (mass transfer coefficients) Equilibrium staged operations (convective mass transfer using departure from equilibrium as a driving force) Mechanical separations (not analogous with other transfer processes) ... 

The random eddy motion of groups of particles resembles the random motion of molecules in a gas—colliding with each other after traveling a certain distance and exchanging momentum and licat in the process. Therefore, momentum and beat transport by eddies in turbulent boundary layers is analogous to the molecular momentum and heat diffusion. Then turbulent wall shear stress and turbulent heat transfer can be expressed in an analogous manner as... 

There are three means of heat transfer that apply to drying processes. These are conduction, convection, and radiation. Conduction is the transfer of heat from one body to another part of the same body, or from one body to another body in direct physical contact with it. This transfer of heat must occur without significant displacement of particles of the body other than atomic or molecular vibrations. Conductive heat transfer is analogous to electrical flow and can be described by similar terms such as potential and resistance. Some examples of conduction would include heating of metal pipes by a hot liquid inside of them, or heat supplied to a solids bed via a metal shelf. 

The last two steps, steps 6 and 7, of the sequence involve the analogous transport of products back to the bulk fluid. Steps 1 and 7 are external physical rate processes which are in series with chemical steps 3-4-5 of adsorption-reaction-desorption in other words, they are separated from the chemical steps. Steps 2 and 6, on the other hand, are internal physical rate processes which are concurrent with chemical steps and require simultaneous treatment of chemical and physical rate processes. Heat transfer between bulk fluid and outer catalyst surfece and within the porous particle is also treated by the same reasoning. 

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