Intro to Injection Molding

Provides a basic understanding of plastic injection molding presses, processes, and costs.

Autonomous Vehicle Engineering

The No. 1 media source for those developing the next generation mobility solutions.

Hydraulics & Pneumatics

For design and manufacturing engineers involved in buying or specifying fluid power components and systems.

Laser Focus World

Semiconductors, medical equipment, lasers, optics and aviation and aerospace.

more free magazines
Similar to forced convection, heat transfer due to free convection is described by Newton's Law of Cooling,
The rate of heat transfered to the surrounding fluid is proportional to the object's exposed area A, and the difference between the object temperature Tw and the fluid free-stream temperature .

The constant of proportionality h is termed the convection heat-transfer coefficient. Other terms describing h include film coefficient and film conductance.

Variables needed to parameterize free convection are:

Definition of Symbols
Independent Parameters for the Fluid
Quantity Symbol Units
  bulk temperature   K
  kinematic viscosity   n m2/s
  coef. of thermal expansion   b 1/K
  dynamic viscosity   m kg/m-s
  density   r kg/m3
  thermal diffusivity   a m2/s
  specific heat   cp J/kg-K
  thermal conductivity   k W/m-K

Independent Parameters for the Object
Quantity Symbol Units
  surface reference length   L m
  surface diameter (for pipes)   D m
  surface (wall) temperature   Tw K

Dependent Parameters
Quantity Symbol Units
  surface to fluid temp. difference   K
  heat transfer coefficient   h W/m2-K