-
-
PROCESSESOur products range from induction melting furnaces ranging from 50kg to 15,000KG capacity, and our induction power suppliers range from 80KW to 12,000KW to meet all melting needs.
-
ADVANTAGEHTGP provides a systematic solution for scrap aluminum melting and casting.
-
EVENTS & NEWS
industrial furnace heat transfer
Release time:
Nov 24,2025
source:
Understanding Convection Heat Transfer: Free and Forced Convection Explained
Convection heat transfer occurs only when each particle within the heat-exchange medium is able to move through space. In other words, the transfer of heat is always accompanied by the movement of the medium itself.
Depending on what causes this movement, convection can be divided into free convection and forced convection.
What Is Free Convection?
Free convection refers to a heat-transfer process driven solely by density differences within the fluid. An example is the cooling of a furnace wall in still air.
The air in direct contact with the heated furnace wall rises due to lower density, while cooler air flows in to replace it. This creates a continuous upward airflow along the furnace wall surface that transfers heat from the wall to the surrounding air.
What Is Forced Convection?
When the movement of fluid particles is mainly caused by external factors—such as pressure differences across fluid flow sections—the process becomes forced convection.
If the velocity of particle movement caused by density differences is much smaller than that caused by external forces, the heat-transfer behavior can be classified as forced convection.
Convection Inside Industrial Furnaces
Inside industrial furnaces, the internal particle velocity caused by density changes is extremely small compared with the overall airflow velocity. It is essentially negligible.
Therefore, convection inside furnaces is generally not considered free convection, but forced convection.
Boundary Layer Behavior in Heat Transfer
Modern understanding of fluid behavior near solid surfaces suggests the presence of a boundary layer—a thin fluid region that is either stationary or moving at a much lower velocity.
Heat travels through this boundary layer primarily by thermal conduction, transferring heat from the wall surface to the core fluid (or in the opposite direction, depending on temperature gradient).
Why Boundary Layer and Thermal Conductivity Matter
For engineers and furnace designers, the critical concern is the heat exchange between the moving fluid and the solid wall surfaces.
Because heat must pass through the boundary layer by conduction, the thermal conductivity of the fluid plays a major role in determining the efficiency of convection heat transfer.
Previous：
We use optional cookies to improve your experience on our site, including through social media connections, and to serve personalized ads based on your online activity. If you refuse optional cookies, we will only use cookies that are necessary to provide you with the service. Privacy Statement
Leave your inquiry now, and get a systematic solution later.
We will contact you within one working day. Please pay attention to your email.
For any product inquiries, technical support, or service requests, contact us below:
WeChat/Whatsapp : 86-17538889778
Tel : 86-379-65188091
Address: No. H3, North Jingjin Road, Dongda Science and Technology Park, Luoxin Industrial Cluster, Luoyang, Henan, China