Lämmönsiirtoalueen

lämmönsiirtoalue refers to the region within a heat exchanger where heat transfer takes place between two different media, typically fluids or gas and solid walls. It is the part of the system that contributes most effectively to the temperature change of the streams. The term is often used in the design, analysis and optimization of condensed heat exchangers, boilers, condensers, evaporators and heat transfer plates.

In a plate‑heat‑exchanger the lämmönsiirtoalue is formed where the hot and cold fluid layers flow in close contact separated by thin plates, allowing heat conduction across the metal barrier. For a shell‑and‑tube exchanger the area is the surface of the tube wall that contacts the fluid in the tube and the fluid in the shell, as well as the finned surfaces or perforations that increase the exposed area.

The performance of the lämmönsiirtoalue is usually quantified by the overall heat‑transfer coefficient, U, which combines convection on both sides of the wall and conduction through the wall itself. Engineers calculate the required area, A, from the heat duty, Q, and the temperature difference, ΔT, via the relation Q = U·A·ΔT. Adjusting the geometry, material, and flow conditions changes U and thus the size of the lämmönsiirtoalue needed for a given duty.

In practice, improving the lämmönsiirtoalue can involve adding fins, increasing turbulence, selecting high‑conductivity materials, or optimizing the flow arrangement. Such modifications reduce the physical size and cost of the exchanger while maintaining the same transfer capability.