lämmönojohtavuus

Lämpöjohtavuus, often denoted by the symbol k, λ, or κ, is a material property that describes its ability to conduct heat. It quantifies how effectively thermal energy is transferred through a material via conduction. Materials with high thermal conductivity, such as metals, readily transfer heat, while materials with low thermal conductivity, such as insulators, resist heat flow. This property is crucial in various engineering applications, including thermal insulation, heat exchangers, and the design of electronic components.

The unit of thermal conductivity in the International System of Units (SI) is watts per meter-kelvin (W/(m·K)). A higher value indicates better heat transfer. For example, copper has a high thermal conductivity, making it suitable for cookware bases and heat sinks, whereas fiberglass, with its low thermal conductivity, is used as insulation in buildings to minimize heat loss or gain.

Thermal conductivity is influenced by factors such as temperature, the material's phase (solid, liquid, gas), and its microstructure. In solids, heat is primarily transferred through lattice vibrations (phonons) and, in metals, also by free electrons. In gases and liquids, heat transfer occurs through molecular collisions. Understanding thermal conductivity is essential for predicting and controlling heat flow in a wide range of physical phenomena and technological processes.