Category Archives: Education

What Is heat transfer coefficient? And How To Calculate It?

March 23, 2012   Education

Heat transfer is one of the basic disciplines among other disciplines of science and engineering; specially related to the chemical or mechanical engineering. The basic concepts about the heat transfer as well as the heat transfer coefficient can be explained as:

WHAT ARE THE MODES OF HEAT TRANSFER?

In actual, heat transfer depends upon the modes of heat transfer, as well as the heat transfer coefficient. There are three modes or ways in which heat is transferred from one system to other system. Those three modes are named as conduction, convection and radiation; and are described below:

CONDUCTION:

What is conduction? Conduction is actually the heat transfer phenomena for solids, as the conduction is basically the transfer of vibration energy from one molecule to other, and solids have the structure in which the molecules are tightly packed. However conduction can occur in fluids too, but mostly the heat transfer in fluids is referred to the term, named convection.

Now, how to calculate heat transfer by conduction? Scientifically, what is conduction can be answered as:

Q = -kAT

CONVECTION

After discussing conduction heat transfer; what is convection then? This is basically the way of heat transfer in fluids, generally in liquids, or between solids and liquids. For example, if water is flowing on a hot solid surface, then the water will take the heat of the solid surface through convection. There are then further classifications of the convection, like the force convection, and the free convection. Now what is convection mathematically and how to calculate it?

Q = hA(T T’)

RADIATION
It is the form of energy, which is associated with the electromagnetism. The sun radiates energy, and transfers by radiation to our world. All material radiates energy, some more, some less. When the electromagnetic waves fall on the body, part of them absorbed, part is reflected. The part, which is absorbed is basically the heat transferred by the radiation.

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