1. Under supercritical conditions,

1. Under supercritical conditions, the density and specific heat capacity of carbon dioxide will increase sharply, and the compressibility will also drop sharply, which is equivalent to that of liquid, while the viscosity and thermal conductivity will drop sharply, which is close to that of gas. The above changes are all in the direction that is conducive to pipeline transportation, so the supercritical state is the most favorable state for large-scale and long-distance pipeline transportation.2. There are three ways to achieve supercritical carbon dioxide. Under the same molar flow rate, the power consumption and energy consumption required to convert from liquid to supercritical state are the smallest, while the energy consumption and heat dissipated by the system when the gas state is first converted to liquid and then further converted to supercritical state are much smaller than the method of directly converting the gas state to supercritical state.3. Due to the large pressure drop in gaseous pipelines, the effective transportation distance after one pressurization is 37.5km. Due to phase limitations, the transportation distance for liquid pipelines is 204.4km. If supercritical pipelines want to maintain supercritical, the transportation distance is 128.1km. If the pressure drop is allowed to be calculated, the transportation distance can reach 1010km. Impurities have a small impact on gaseous and supercritical pipelines, but a significant impact on liquid pipelines. When the distance exceeds 100km, The impact is particularly significant.