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Supercritical carbon dioxide (s CO 2 ) is a fluid state of carbon dioxide where it is held at or above its critical temperature and critical pressure . Carbon dioxide usually behaves as a gas in air at standard temperature and pressure (STP), or as a solid called dry ice when cooled and/or pressurised sufficiently.
Efficient supercritical CO 2 power cycles requires that the compressor inlet temperature is close to, or even lower than, the critical temperature of the fluid (31 °C for pure carbon dioxide). When this target is reached, and the heat source is higher than 600–650 °C, then the sCO 2 cycle outperforms any Rankine cycle running on water ...
Supercritical water oxidation uses supercritical water as a medium in which to oxidize hazardous waste, eliminating production of toxic combustion products that burning can produce. The waste product to be oxidised is dissolved in the supercritical water along with molecular oxygen (or an oxidising agent that gives up oxygen upon decomposition ...
‡ Second column of table indicates solubility at each given temperature in volume of CO 2 as it would be measured at 101.3 kPa and 0 °C per volume of water. The solubility is given for "pure water", i.e., water which contain only CO 2. This water is going to be acidic. For example, at 25 °C the pH of 3.9 is expected (see carbonic acid).
Carbon dioxide (CO 2) is the most used supercritical fluid, sometimes modified by co-solvents such as ethanol or methanol. Extraction conditions for supercritical carbon dioxide are above the critical temperature of 31 °C and critical pressure of 74 bar. Addition of modifiers may slightly alter this.
Supercritical carbon dioxide (CO 2) is the most commonly used supercritical fluid because of its relatively easy to use. Temperatures above 31 °C and pressures above 7.38 MPa are sufficient to obtain supercriticality, [ 5 ] at which point it behaves as a good nonpolar solvent .
Anisimov et al. (2004), [11] without referring to Frenkel, Fisher, or Widom, reviewed thermodynamic derivatives (specific heat, expansion coefficient, compressibility) and transport coefficients (viscosity, speed of sound) in supercritical water, and found pronounced extrema as a function of pressure up to 100 K above the critical temperature.
The Allam-Fetvedt Cycle is a recuperated, high-pressure, Brayton cycle employing a transcritical CO 2 working fluid with an oxy-fuel combustion regime. This cycle begins by burning a gaseous fuel with oxygen and a hot, high-pressure, recycled supercritical CO 2 working fluid in a combustor.