One-dimensional numerical analysis of CO₂ capture by desublimation in an isopentane spray tower

Carbon capture technology is a focal point in the realm of carbon capture, utilization, and storage. Enhancing CO₂ capture efficiency and reducing energy consumption are pivotal for the viability of industrial applications and the attainment of the "carbon peaking and carbon neutrality" objective. Cryogenic CO₂ capture by desublimation is a post-combustion capture technology that has the advantages of high CO₂ capture rate, environmental friendliness, and the production of high-purity CO₂ products. Consequently, it holds substantial potential for both academic research and industrial applications. Nevertheless, conventional CO₂ desublimation capture methods using solid media present limitations, including challenges in collecting and removing solid CO₂, compromised heat transfer between solid media and gaseous CO₂, and corrosion issues. Although utilizing liquid media for desublimating and capturing CO₂ can overcome these challenges, pertinent research remains insufficient. This study employs the cryogenic carbon capture method, utilizing liquid media to desublimate CO₂. It establishes a one-dimensional model for the isopentane spray tower to examine the temperature and CO₂ concentration fields within the tower. The aim is to elucidate the relationships and physical mechanisms governing the tower's overall CO₂ capture rate in relation to the initial conditions of the inlet gas, isopentane droplets, and spray tower settings. Numerical results from the one-dimensional isopentane spray tower revealed the following: (1) The temperature variation of isopentane droplets was minimal and primarily occurs around the gas inlet area, indicating that desublimation was contingent upon CO₂ concentration fields and mass diffusion. (2) The temperature of the CO₂ mixture gas undergone significant changes throughout the tower at a constant rate, highlighting the dominance of gas temperature fields by thermal convection with negligible effects from droplet desublimation on gas temperature. (3) The initial diameters and temperatures of isopentane droplets significantly affected the spray tower's overall CO₂ capture rate. Initial diameters smaller than 2.0-mm and initial temperatures below 150.00 K for isopentane droplets result in a CO₂ capture exceeding 90% for a 2.0-m high spray tower, validating the efficacy and efficiency of the isopentane spray tower in cryogenic CO₂ capture. (4) The spray tower's overall CO₂ capture rate was influenced by the tower's height, initial velocity and temperature of isopentane droplets, and inlet gas velocities. The efficiency of the desublimation process was strongly dependent on the heat transfer efficiency and contact time between isopentane droplets and CO₂ mixture gases. Through numerical simulation and investigation of temperature and CO₂ concentration fields within the isopentane spray tower, this study unveils and analyzes factors influencing the tower's CO₂ capture rate and the pertinent mechanisms of CO₂ desublimation on liquid droplets. Additionally, it demonstrates the effectiveness of the isopentane spray tower in capturing CO₂, emphasizing the substantial potential for cryogenic CO₂ capture using liquid spray in the field of carbon capture.