Thermal conductivity measures the ability of a metal to conduct heat. This property varies across different types of metal and is important to consider in applications where high operating temperatures are common.
In pure metals, thermal conductivity stays roughly the same with increases in temperature. However in alloys the thermal conductivity increases with temperature.
Which metals conduct heat best
|Common metals ranked by thermal conductivity|
|Rank||Metal||Thermal Conductivity [BTU/(hr·ft⋅°F)]|
As you can see, out of the more common metals, copper and aluminum have the highest thermal conductivity while steel and bronze have the lowest. Heat conductivity is a very important property when deciding which metal to use for a specific application. As copper is an excellent conductor of heat, it’s good for heat exchangers, heat sinks, and even saucepan bottoms. Because steel is a poor conductor of heat, it’s good for high-temperature environments like airplane engines.
Here are some important applications which require metals that conduct heat well:
A heat exchanger is a common application where good thermal conductivity is important. Heat exchangers do their job by transferring heat to achieve heating or cooling.
Copper is a popular choice for heat exchangers in industrial facilities, air conditioning, refrigeration, hot water tanks and under-floor heating systems. Its high thermal conductivity allows heat to pass through it quickly. Copper has additional properties desirable in heat exchangers including resistance to corrosion, biofouling, stress and thermal expansion.
Aluminum can also be used in some heat exchanger applications as a more cost-effective alternative.
Heat exchangers are commonly used in the following situations:
Heat exchangers in industrial facilities include fossil and nuclear power plants, chemical plants, desalination plants and marine services.
In industrial facilities copper-nickel alloy is used to construct the heat exchanger tubing. The alloy has good corrosion resistance which protects against corrosion in saltwater environments. It also has good biofouling resistance to avoid formation of algae and sea mosses. Aluminum-brass alloy has similar properties and can be used as an alternative.
Solar thermal water systems
Solar water heaters are a cost-effective way to heat water in which a copper tube is used to transfer the solar thermal energy to the water. Copper is used because of copper’s high thermal conductivity, resistance to air and water corrosion, and mechanical strength.
Gas water heaters
Gas water heat exchangers transfer the heat generated by gas fuels to water. They’re common in residential and commercial boilers. For gas water heaters, copper is the preferred material because of its high thermal conductivity and ease of fabrication.
Forced air heating and cooling
Heat pumps using air have long been used for residential and commercial heating. They work via air-to-air heat exchange through evaporator units. They can be used in wood furnaces, boilers, and stoves. Again, copper is typically used for its high thermal conductivity.
Heat sinks are a type of heat exchanger that transfers heat generated by an electronic or mechanical device into a moving coolant fluid. The fluid transfers the heat away from the device, allowing it to cool to the desired temperature. Metals with high thermal conductivity are used.
Computers use heat sinks to cool central processing units or graphics processors. Heat sinks are also used in high power devices like power transistors, lasers and light emitting diodes (LEDs).
Heat sinks are designed to maximize the surface area in contact with the coolant fluid.
Aluminum alloys are the most common heat sink material. This is because aluminum costs less than copper. However copper is used where higher levels of thermal conductivity are needed. Some heat sinks use a combination aluminum fins with a copper base.
A more household use of metal with good thermal conductivity is in cookware. When you’re heating up your food, you don’t want to wait all day. That is why copper is used in the bottoms of high-quality cookware because the metal rapidly conducts the heat and spreads it evenly across its surface.
However, if you’re on a budget you can use aluminum cookware as an alternative. It may take a little longer to heat up your food, but your wallet will thank you for it!
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At Metal Supermarkets, we supply a wide range of metals for a variety of applications. Our stock includes: stainless steel, alloy steel, galvanized steel, tool steel, aluminum, brass, bronze and copper.
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The thermal conductivity of a material determines how good an insulator it is. The official definition of thermal conductivity is the quantity of heat transmitted through a unit thickness in a direction normal to a surface of unit area, due to a unit temperature gradient under steady state conditions. A simpler way of saying this is: thermal conductivity is the ability to conduct heat. The best materials for insulation are the ones with the lowest thermal conductivity.
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Thermal conductivity is commonly described in terms of how fast a unit of heat, called a BTU, or British Thermal Unit, can travel through 1 foot of material in one hour due to 1 degree F of difference.
Glass is far inferior to paper, plastic and Styrofoam in terms of insulation. Thermal conductivity in terms of BTU/(feet - hour - degrees F) is 1.82 for glass, 0.09 for paper, 0.06 for Styrofoam. The conductivity of plastics varies depending on the materials: for polypropylene and polycarbonate, the thermal conductivity values are 0.69 and 0.35, respectively.
Paper, glass, plastic and Styrofoam are common materials used in containers holding hot beverages. Considering containers of the same size, a glass container is the least effective for keeping a cup of coffee warm. Though not commonly used in the United States, using elegant glass cups for serving coffee or other hot drinks is common in Austria, Spain and India.
It’s a common sight to see people walking around carrying coffee in paper or Styrofoam cups. The insulative values of paper and Styrofoam aren't that different, but Styrofoam cups generally are much thicker than paper ones, so they keep your coffee hot longer. However, drinking from a Styrofoam cup is unappealing to many people because it’s not the most eco-friendly choice. Paper biodegrades much faster than Styrofoam.
Many coffee travel mugs are made of hard plastic, either polystyrene or polycarbonate. Their insulative values are higher than glass, but lower than paper. Plastic travel mugs are tougher and thicker than either paper or Styrofoam cups. This not only improves the insulative ability of plastic mugs, but also makes them a safer choice in terms of driving with scalding hot drinks.
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