Energy Transfer
All process in engineering involve the transfer of energy. Some examples are the heating and cooling of process streams, phase changes, distillations, etc. The basic principle is the law of thermodynamic which is expressed as follows for a static system:
For other systems that involve either turbulent flow, complex geometries or difficult boundary conditions another equation would be easier to use:
where A is the surface area, : is the temperature driving force, q is the heat flow per unit time, and h is the heat transfer coefficient.
Within heat transfer, two types of convection can occur:
Forced convection can occur in both laminar and turbulent flow. In the situation of laminar flow in circular tubes, several dimensionless numbers are used such as Nusselt number, Reynolds number, and Prandtl. The commonly used equation is:
Natural or free convection is a function of Grashof and Prandtl numbers. The complexities of free convection heat transfer make it necessary to mainly use empirical relations from experimental data.
Heat transfer is analyzed in packed beds, reactors and heat exchangers.
Read more about this topic: Transport Phenomena
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