Forced convection

Definition

Forced convection is a mechanism of heat transfer where fluid motion is generated by an external source like a pump, fan, or mixer. This process enhances heat transfer efficiency compared to natural convection.

5 Must Know Facts For Your Next Test

1. Forced convection increases the rate of heat transfer by increasing the fluid velocity.
2. The heat transfer coefficient in forced convection is generally higher than in natural convection.
3. Common applications include heating and cooling systems, where fans or pumps are used to circulate air or liquid.
4. The governing equation for forced convection is Newton's Law of Cooling: $q = hA(T_s - T_\infty)$, where $h$ is the convective heat transfer coefficient.
5. Dimensionless numbers like Reynolds number (Re) and Nusselt number (Nu) are often used to characterize forced convection.

Review Questions

• What role does an external source play in forced convection?
• How does forced convection compare with natural convection in terms of heat transfer efficiency?
• What are some common applications that utilize forced convection?

Related terms

Natural Convection: A type of heat transfer where fluid motion is caused by buoyancy forces due to density differences resulting from temperature gradients.

Reynolds Number: A dimensionless number used to predict flow patterns in different fluid flow situations; defined as $Re = \frac{\rho u L}{\mu}$.

Nusselt Number: A dimensionless number representing the ratio of convective to conductive heat transfer across a boundary; defined as $Nu = \frac{hL}{k}$.