Soojusvoo

Soojusvoo is a term used in Estonian-language contexts to denote the flow of thermal energy through a material or boundary, effectively the heat transfer rate per unit area. In standard thermodynamics, this quantity is known as heat flux and is governed by Fourier's law, which states that the heat flux vector q equals minus the thermal conductivity k times the temperature gradient ∇T. In practical one-dimensional form, the scalar heat flux density is q'' = -k ∂T/∂x, and the total heat transfer through a surface of area A is Q = q'' A. The common unit for heat flux is watts per square metre (W/m^2).

Etymology and usage: Soojus means heat and voo or voog denotes flow; the term soojusvoog is widely used for heat flow, while soojusvoo appears in some dialectal or informal usages as a variant. In most technical texts, soojusvoog is the standard form, but soojusvoo may be encountered in certain regions or transliterations.

Applications: The concept is central to building physics (evaluating insulation and heat loss), electronics cooling, HVAC design, geothermal systems, and industrial heat exchangers. It is also used in climate and environmental studies to describe heat exchange at surfaces or interfaces.

Measurement and modeling: Heat flux can be measured with heat flux sensors or inferred from temperature measurements and known material properties. In simple steady-state conduction, q'' is uniform across a plane; in more complex or transient cases, vector forms and time dependence are required, and numerical methods are often employed.