What is Heat Transfer?

Ken Black

Heat transfer is the process of moving heat from a location where much heat exists to another location. In physics, it is taught this is mainly accomplished one of three ways: conduction, convection or radiation. In some ways, using this knowledge helps humans manipulate thermal energy in ways that are most beneficial.

A pan on a stove's burner transfers heat through conduction.
A pan on a stove's burner transfers heat through conduction.

Understanding the principles behind heat transfer helps people do a number of activities more efficiently. From providing adequate heat in a home to providing options for cooking various foods, heat transfer plays a vital role in everyone's lives. The uses of heat transfer are nearly endless.

Steam transfers heat into the air, which is why it's often used to heat buildings.
Steam transfers heat into the air, which is why it's often used to heat buildings.

Conduction is one of the most common ways to transfer heat. This is done by transferring heat through matter from one atom to the next. It is most commonly experienced when a piece of metal, such as a cooking spoon, is left too long in a hot liquid. The heat will travel up the spoon. Some materials are more conductive than others, which is why metal pots often have rubber handles and why cooking utensils also come in wood and plastic varieties.

Conduction is a type of heat transfer that can also be easily experienced in other ways, such as when holding a piece of metal. Often, the metal will feel cool to the touch, even though it is actually the same temperature as anything else in the room or area. What is really taking place is a heat transfer between your body and the metal. The metal is actually taking heat away from your skin.

Convection is the actual physical movement of heat from one location to another in the form of liquid or gas. Generally hot air, and heat in general, rises, which is why steam from a boiling pot goes up. This concept can be clearly demonstrated on a hot day and is responsible for moderating temperatures near the oceans and see breezes. As warm air rises from the land in the afternoon and early evening, cooler air over the water moves in and takes its place, causing a breeze toward the shore.

The opposite is true in the morning. Since the air over the water does not cool as fast, it rises in the morning and is replaced by air over land. Thus, the sea breeze actually blows out toward the sea at that time.

The other type of heat transfer is radiation. While many have become concerned after hearing about the bad effects of radiation and its ability to cause cancer, this type of heat transfer is responsible for most of warmth our planet receives. Radiation occurs when heat travels via electromagnetic waves through seemingly empty voids, such as the sun's heat traveling through space. Radiation is responsible for traditional baking as well as cooking in a microwave oven.

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Discussion Comments


What kind of heat transfer can is seen when heat travels through a cooking spoon?


Thermals are a form of convection, where the heat of the land causes the air to warm and then rise. This is particularly acute in urban areas, where the buildings, roads, sidewalks, parking lots, etc... retain and reflect heat during the day. Birds typically use this form of convection to remain airborne with the minimum of effort, hence "riding the thermals".


What are thermals?

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