Pumping gaseous CO_2 into a high-pressure, constant-volume storage cylinder: A thermodynamics analysis

摘要

A thermodynamic model is developed to predict the pressure, temperature, and density of CO2 when it is compressed into a high-pressure, constant-volume storage cylinder. The model incorporates the effects of the compressibility of the fluid. Heat loss to the surrounding environment and heating of the cylinder walls are also considered. The basic equations are non-dimensionlized. Variations of CO2 pressure, temperature, and density inside the cylinder during the pumping process are investigated using the heat loss to the surrounding, the heat used to heat the cylinder walls, and the compression power as the parameters. The results show that CO2 pressure is not sensitive to the heat loss, but it does depend on the compression power. For the range of the heat loss and the cylinder heating that are found in many practical situations, CO2 temperature inside the cylinder increases to a maximum value of about 7 K above the surrounding temperature, and the pumping can be modeled as a polytropic process, where PVn = constant with the polytropic exponential power n = 0.995.