warmtetransport

Warmtetransport, or heat transport, is the process by which thermal energy moves within a material or between bodies due to a temperature difference. It is a central concept in thermodynamics and heat transfer, influencing everything from industrial processes to building design and electronic device performance.

In classical theory, heat transport occurs through three mechanisms: conduction, convection, and radiation. Conduction involves microscopic energy transfer within and between materials. In solids, it mainly occurs via lattice vibrations (phonons) and, in metals, free electrons. Fourier's law describes steady conduction: q = -k ∇T, where q is the heat flux, k is the thermal conductivity, and ∇T is the temperature gradient. Thermal conductivity depends on material structure and can be anisotropic in some crystals.

Convection involves energy transport by the bulk motion of fluids. It can be natural, driven by buoyancy from density differences, or forced, using pumps or fans. The convective heat transfer rate is often represented as q_conv = hA (T_s - T_f), with h as the convective heat transfer coefficient and A the surface area. Boundary layers and flow conditions strongly influence h.

Radiation transfers energy by electromagnetic waves and can occur across vacuum. It does not require a medium. The Stefan–Boltzmann law gives q_rad = ε σ (T^4 - T_env^4), where ε is emissivity, σ the Stefan–Boltzmann constant, and T and T_env are absolute temperatures. Surface geometry and view factors matter.

Key properties used to characterize warmtetransport include thermal conductivity k, density ρ, and specific heat c_p. Thermal diffusivity α = k/(ρ c_p) describes how quickly a material responds to temperature changes. Measurements employ steady-state (e.g., guarded hot plate) or transient (e.g., hot-wire, laser flash) methods.

Applications span electronics cooling, building envelope design, manufacturing, and energy systems, making accurate heat transport modeling essential across engineering disciplines.