ainesiirrosta

Ainesiirrosta refers to the physical process of mass transfer, the movement of matter from regions of higher concentration or chemical potential to regions of lower concentration. It applies to gases, liquids, and solids and encompasses diffusion, advection (convection), and interfacial transfer across phase boundaries or membranes.

Diffusion is driven by concentration gradients and is described by Fick's laws. Convection results from bulk fluid motion, often represented by mass transfer coefficients. Interfacial transfer occurs at phase boundaries and through porous media or membranes and can be rate-limited by membrane resistance or boundary layer effects. The overall rate depends on driving forces, phase properties, temperature, and geometry.

Applications span chemical engineering, environmental science, food technology, and biomedicine. Examples include oxygen transfer between air and water, mass transfer in drying and crystallization, gas absorption in reactors, and dialysis in medicine. Modelling commonly uses mass balance equations and dimensionless numbers such as Peclet, Sherwood, and Reynolds to characterize regimes.

Measurement typically employs tracer techniques, permeation tests, and gas absorption experiments, while modelling combines analytical solutions for simple geometries with numerical methods for complex systems. The term is widely used in Finnish-language literature on transport phenomena and is aligned with international concepts of mass transfer and diffusion.