In-tube convective heat transfer characteristics of CO2 mixtures in a pipeline

Abstract

In the Carbon Capture, Transportation & Storage (CCS) process, CO2 is captured with impurities such as N2, CH4 and Ar and is transported under a supercritical state. In this study, the characteristics of in-tube convective heat transfer of CO2 mixtures such as CO2 + N2, CO2 + CH4 and CO2 + Ar were experimentally investigated under the land transportation conditions of the CCS process. The test tube was made of a cooper tube buried in a PVC (Polyvinyl Chloride) pipe which was compactly filled with sand, which simulated the land CO2 transportation. Mass flux was changed by 200, 400 and 600 kg m−2 s−1, and operational pressures were 80, 90, and 100 bar. Operational temperatures ranged from 25 to 55 °C. The heat transfer coefficient of the CO2 mixtures dominantly followed the trends of pure CO2; however, they were decided by the type and quantity of the impurity. When the CO2 mole fraction was changed from 1.00 to 0.95, the maximum heat transfer coefficient at the pseudo-critical temperature of CO2 + N2 and CO2 + CH4 decreased by 4389 W·m−2 K−1 and 2770 W·m−2 K−1, respectively. As the mass flux increased, the heat transfer coefficient increased in all of the CO2 mixtures.