Lämmönsiirtokerroin

Lämmönsiirtokerroin, often denoted by the symbol $h$, is a fundamental concept in heat transfer engineering. It quantifies the rate of heat transfer between a fluid and a solid surface per unit area and per unit temperature difference. Essentially, it describes how effectively heat is transferred across the boundary between the two media. A higher lämmönsiirtokerroin indicates more efficient heat transfer.

The lämmönsiirtokerroin depends on several factors, including the properties of the fluid such as its viscosity, thermal conductivity, density, and specific heat capacity. The flow regime of the fluid, whether it is laminar or turbulent, also plays a significant role. Surface characteristics, such as roughness and geometry, can also influence the heat transfer coefficient.

In convective heat transfer, the lämmönsiirtokerroin is crucial for calculating heat exchange rates in applications like heat exchangers, radiators, and cooling systems. It is determined experimentally or through complex theoretical analyses involving dimensionless numbers like the Nusselt number, Reynolds number, and Prandtl number. The units of lämmönsiirtokerroin are typically watts per square meter per Kelvin (W/(m²·K)) or watts per square meter per degree Celsius (W/(m²·°C)). Understanding and accurately determining the lämmönsiirtokerroin is essential for designing efficient thermal systems and predicting their performance.