A theoretical study has been carried out to investigate the performance of the TSI 3020 condensation nucleus counter (CNC) at various pressures and flow rates by assuming a parabolic velocity profile in the condenser tube and solving the heat and mass transfer equations using the finite difference method. Calculations have been performed for pressures ranging from 0.03 to 10 atm and sampling flow rates from 0.5 to 50 mL 1s. The results indicate that the counting efficiency of the CNC is a function of pressure and flow rate due to changes in heat and mass transfer rates. The counting efficiency can be correlated with a single parameter, f , which combines the effects due to pressure, sampling flow rate, and the length and diameter of the condenser tube. The cut size of the instrument, Dp,,, defined as the particle size at which the counting efficiency is 50%, has been found to vary with pressures, reaching a minimum at a pressure of approximately 1 atm. The cut size of the CNC has been found to be most sensitive to the temperature difference between the saturator and condenser but relatively insensitive to the flow rate and the saturator temperature.

Petroleum-based liquids are from an important petroleum-based polymer, whose application and preparation involve multiple operations related to gas–liquid two-phase flow. Due to insufficient research on gas–liquid two-phase flow, there is a gap in bubble dynamics and mass transfer characteristics in petroleum-based liquids. Accordingly, we have systematically investigated the bubble formation process, bubble rising dynamics, and mass transfer of coaxial bubbles. Herein, the contour of bubbles was obtained for analyzing the bubble formation process. It was found that the increase of gas flow rate contributed to the increase of bubble generation size, while the liquid viscosity had an inhibitory influence on the increase of bubble generation size. Moreover, the variation of bubble rising velocity was considered and the force analysis of the rising bubble was provided. A new model of drag coefficient applicable to petroleum-based liquids was proposed. Finally, variations in the amount of dissolved oxygen in the liquid were measured to analyze the mass transfer characteristics. The increase in nozzle inner diameter and gas flow rate both promoted mass transfer, but the increased liquid viscosity hindered mass transfer.

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Reservoir wettability representing the competitive adsorption for different fluids on the surface, helps to predict the capture capacity and risk assessment for CO2 geological sequestration. Numerous simulated models have been applied to reveal rock wettability with various pressures. However, most papers investigated the wettability alteration without considering CO 2 flow in the pores. There required an accurate model to describe the change in wettability of the reservoir during CO 2 injection. In this paper, the molecular simulation was conducted to investigate the wettability alteration of reservoirs during the CO 2 injection process. Considering the continuous CO 2 injection, we employed a model referring to quartz-CO2-solution. In this model, CO2 flow is regarded as a stationary layer. After that, we studied the wetting behavior of reservoirs with various pressures ranging from 0 MPa to 62.3 MPa. The results show that the contact angle first dramatically increases until 12.2 MPa from 67 °to 102.9 °and after that enters a ramp region and ultimately reaches a finial value 120.7 °, which shows the CO 2 injection pressure weakens the water-wet property of reservoirs. Water clusters predicting the wettability are hard to move through the CO2 atmosphere with the increase of pressure. Thus, the water cluster exhibits a hysteresis at a high pressure, resulting in the water cluster being hard to change and expend a long time to be equilibrated. Moreover, it is noted that the interaction of rock-CO 2 gradually increases with the increase of pressure, indicating that more CO 2 can be captured in tight sandstones. This paper proposed a model considering CO2 flow in the CO2 injection process, which can deepen the understanding of the wettability alteration in different CO 2 densities during CO 2 injection for CO 2 geological sequestration, which further guides the operation of CO 2 in Carbon Capture, Utilization and Sequestration project.