Allirreversibilità

Allirreversibilità is a term used in thermodynamics to describe the total irreversibility of a process. It denotes the deviation between a real, irreversible path and the ideal reversible path that would connect the same initial and final states. In this sense, allirreversibilità encompasses all sources of entropy production within the system and its surroundings.

The concept is typically quantified through entropy generation. The total entropy produced during a process measures the irreversibility: higher entropy production indicates greater irreversibility. The irreversibility can be thought of as the energy that becomes unavailable to do useful work, often linked to the exergy destroyed in the surroundings. Common contributors to allirreversibilità include heat transfer across finite temperature differences, viscous dissipation, mixing of substances, chemical reactions, and phase changes.

Decomposition of allirreversibilità helps engineers target improvements. For example, in a heat exchanger, irreversibility may arise mainly from large temperature differences; in a chemical reactor, from reaction heat and incomplete mixing; in a turbine, from friction and throttling losses. By identifying dominant sources, designers can reduce overall irreversibility, improving efficiency and reducing energy waste.

Relation to broader ideas is also important. Allirreversibilità is tied to the second law of thermodynamics and the natural direction of processes, contributing to the arrow of time. It provides a framework for evaluating system performance and for comparing real processes with their ideal reversible counterparts.

See also: entropy, irreversibility, exergy, second law of thermodynamics.