Convection is classified as natural (or free) and forced convection depending on how the fluid motion is initiated
. Whereas in forced convection, the fluid is forced to flow over a surface or in a tube by external means such as a pump or fan.
Which is the example of free convection?
Everyday Examples of Convection
radiator
– A radiator puts warm air out at the top and draws in cooler air at the bottom. steaming cup of hot tea – The steam you see when drinking a cup of hot tea indicates that heat is being transferred into the air. ice melting – Ice melts because heat moves to the ice from the air.
What is the difference between free convection and natural convection?
Natural convection, known also as free convection is a mechanism, or type of mass and heat transport, in which the fluid motion is generated only by
density differences in the fluid occurring due to temperature gradients
, not by any external source (like a pump, fan, suction device, etc.).
What is meant by forced convection?
Forced convection is
a mechanism or a type of transport in which fluid motion is generated by an external source
(such as a pump, fan, suction device, etc.
Why is forced convection better?
Forced convection
creates a more uniform and therefore comfortable temperature throughout the entire home
. This reduces cold spots in the house, reducing the need to crank the thermostat to a higher temperature, or putting on sweaters.
What are three types of convection?
- Natural convection.
- Forced convection.
What are 4 examples of convection?
- Breeze. The formation of sea and land breeze form the classic examples of convection. …
- Boiling Water. Convection comes into play while boiling water. …
- Blood Circulation in Warm-Blooded Mammals. …
- Air-Conditioner. …
- Radiator. …
- Refrigerator. …
- Hot Air Popper. …
- Hot Air Balloon.
What is the reason for free convection?
The driving force for natural convection is
gravity
. For example if there is a layer of cold dense air on top of hotter less dense air, gravity pulls more strongly on the denser layer on top, so it falls while the hotter less dense air rises to take its place. This creates circulating flow: convection.
What are the two types of convection?
There are two types of convection:
natural convection and forced convection
.
What is convection explain with an example?
Answer: Everyday Examples of Convection
Boiling water
– The heat passes from the burner into the pot, heating the water at the bottom. Then, this hot water rises and cooler water moves down to replace it, causing a circular motion. Radiator – Puts warm air out at the top and draws in cooler air at the bottom.
What is the most important parameter forced convection?
The parameter of importance in forced convection is
the Péclet number
, which is the ratio of advection (movement by currents) and diffusion (movement from high to low concentrations) of heat. When the Peclet number is much greater than unity (1), advection dominates diffusion.
What causes natural convection?
Natural convection arises
from temperature differences among air parcels
, or heat transfer at surfaces (i.e. surface-to-air temperature difference). In the absence of forced convection, natural convection becomes the only means of air mixing inside enclosed spaces.
Is wind natural or forced convection?
The convection caused by winds is
natural convection
for the earth, but it is forced convection for bodies subjected to the winds since for the body it makes no difference whether the air motion is caused by a fan or by the winds.
Which convection is better natural or forced?
The key difference between natural and
forced convection
is that in natural convection, the motion of the fluid is influenced by natural means whereas, in forced convection, the motion of fluids is influenced by external means.
Is blood flow forced convection?
The heat transfer between arterial and venous blood is very efficient due to the forced
convection
which maintains temperature gradient between arteries and veins.
Can natural and forced convection happen at the same time?
(Discuss) Proposed since April 2021. Combined forced convection and natural convection, or mixed convection, occurs when natural convection and forced convection mechanisms
act together to transfer heat
. This is also defined as situations where both pressure forces and buoyant forces interact.
