Methods Of Heat Transfer

“Nothing happens until something moves.”
-Albert Einstein

These five words are the foundation on which the science of physics is built upon. This statement not only applies to the things we can see, but to those we can’t…like heat transfer.

OK; technically, we CAN visually observe the EFFECTS of heat transfer…that’s called “reading a thermometer.” But the actual mechanism of heat transfer takes place at a molecular level, and concerns the rate of motion of those molecules: the higher the rate of molecular motion, the higher the heat of the material. Hence, the higher the rate of CHANGE of that molecular motion, the higher the heat transfer rate is.

All you need for heat transfer to occur is a difference in temperature between two materials. Contact, or even proximity, helps…but not always. More on that in a minute. And keeping at least one of the materials in motion can help maintain the temperature differential. We’ll unpack that a little more too.

Let’s start with the three ways that heat is transferred…what they are, and how they work:

Conduction

What it is: The transfer of heat between materials that are in physical contact with each other.

How it works: If you’ve ever touched a hot burner on a stove, you’ve successfully participated in the process of conduction heat transfer.

Convection

What it is: The transfer of heat through a fluid medium, enhanced by the motion of the fluid.

How it works: If you’ve ever boiled water in a pan on a hot stove burner, you’ve successfully participated, again, in the process of conduction heat transfer (as the burner heats the pan) AND convection (as the heated water in the bottom of the pan both transfers heat through its volume, and moves to the surface.)

Radiation

What it is: Remember what I said earlier about how you don’t always need contact or proximity for heat transfer? Well, this is it…the transfer of heat through empty space, via electromagnetic waves.

How it works: If you didn’t actually TOUCH the hot stove burner, but felt your hand getting hot as it hovered, then you’ve successfully participated in the process of radiation heat transfer. OK; it’s a little convection too, since the air between the burner and your hand was also transferring some of that heat. The best example of STRICTLY radiation heat transfer I can think of is the sun’s rays…they literally pass through 93 million miles of empty space, and make it quite warm on a nice sunny day here on Earth.

Regardless of how material, or an object, or a system receives heat, engineered compressed air products can be used to efficiently and effectively remove that heat.  For the record, they employ the principles of both conduction and convection.  If you’d like to discuss a heat transfer application, and the way(s) that an EXAIR product can work in it, give me a call.

Russ Bowman
Application Engineer
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