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A supercritical fluid (SCF) is a substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. [1]
One example is the liquid–vapor critical point, the end point of the pressure–temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas comes into a supercritical phase, and so cannot be liquefied by pressure alone.
Supercritical carbon dioxide can be used as a solvent in dry cleaning. [4] Supercritical carbon dioxide is used as the extraction solvent for creation of essential oils and other herbal distillates. [5] Its main advantages over solvents such as hexane and acetone in this process are that it is non-flammable and does not leave toxic residue.
A transcritical cycle is a closed thermodynamic cycle where the working fluid goes through both subcritical and supercritical states. In particular, for power cycles the working fluid is kept in the liquid region during the compression phase and in vapour and/or supercritical conditions during the expansion phase.
This fundamental law determines the different adsorption mechanism for the subcritical and supercritical regions. For the subcritical region, the highest equilibrium pressure of adsorption is the saturation pressure of adsorbate. Beyond condensation happens. Adsorbate in the adsorbed phase is largely in liquid state, based on which different ...
Supercritical drying, a process used to remove liquid in a precisely controlled way, similar to freeze drying; Supercritical fluid, a substance at a temperature and pressure above its thermodynamic critical point: Supercritical carbon dioxide:
The prediction of a vapor–liquid equilibrium is successful even in mixtures containing supercritical components. However, the mixture has to be subcritical. In the given example carbon dioxide is the supercritical component with T c = 304.19 K [4] and P c = 7475 kPa. [5] The critical point of the mixture lies at T = 411 K and P ≈ 15000 kPa ...
This pressure is given by the saturated vapour pressure, and can be looked up in steam tables, or calculated. [9] As a guide, the saturated vapour pressure at 121 °C is 200 kPa, 150 °C is 470 kPa, and 200 °C is 1550 kPa. The critical point is 21.7 MPa at a temperature of 374 °C, above which water is supercritical rather than superheated ...