Selfcooling

Selfcooling is a term used to describe systems or processes that reduce their own temperature without requiring continuous external cooling input. In many contexts it relies on internal energy-absorbing mechanisms such as phase changes, chemical reactions, or the expansion of a gas.

The main mechanisms include evaporative cooling, where liquid water or other liquids lose heat as some molecules escape as vapor; phase change materials absorb latent heat during solid–liquid transitions, stabilizing temperature around a target point. Endothermic dissolution, such as the mixing of certain salts in water, also lowers temperature by absorbing heat. Adiabatic expansion, in which a gas cools as it expands without exchanging heat with its surroundings, can contribute in certain devices, though it often requires a mechanism to allow volume increase.

In nature, selfcooling effects are common. Sweating and plant transpiration transfer heat away from surfaces, producing a cooling effect. Radiative cooling at night or dew formation can also reduce surface temperatures without active energy input.

Technological applications pursue passive cooling designs that require little or no external energy. These include buildings and textiles incorporating phase change materials to absorb heat, electronics enclosures designed to enhance evaporative or radiative cooling, and some consumer products advertised as self-cooling through integrated cooling packs or materials. Limitations include finite cooling capacity, eventual thermal balance with the surroundings, potential material safety concerns, and the need for periodic regeneration or replacement of cooling components. Selfcooling remains a topic of study in thermodynamics and materials science for improving energy efficiency and thermal management.