Analysis of CO2 frost formation properties in cryogenic capture process

With the development of CO2 capture technologies, the cryogenic approach provides a promising alternative for greenhouse effect mitigation. In previous work, a novel CO2 capture process was developed based on Stirling coolers (SC). However, the properties of frosted CO2 that deposits onto the heat exchanger of SC are not completely understood but it plays an important role as a heat transfer medium and affects subsequent CO2 deposition. In order to improve the system performance and capture efficiency, a thorough analysis of the CO2 frost process becomes especially significant. Based on this aim, numerical and experimental analysis of CO2 frost formation in the cryogenic capture process has been investigated in the present work. The results show that the frosted CO2 layer significantly influences the heat transfer between the gas stream and cooling fins. Over time (from 0 to 60 min), the thickness of the frost layer increased from 0 to 3.0 mm. The thermal conductivity increased from 0 to 0.4 W/(m K). When the flow rate was set at 1 L/min, the temperature of the cold head of the SC varied from −105.2 °C to −102.1 °C. When the flow rate was 3 L/min, the temperature rose from −106.3 °C to −98.0 °C.

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► The CO2 frost deposition process in Stirling cooler based cryogenic capture technology has been numerically studied.
► The analysis of frost layer growth process is significant to enhance the whole capture performance.
► The variation tendency of frost layer thickness (δf) and thermal conductivity (λf) are simulated.