Carbon capture, utilization, and storage (CCUS) technologies are the most effective methods to reduce CO₂ emissions from fossil fuel power plants. Of the different CCUS technologies, cryogenic carbon capture (CCC) methods are the most mature technology as they can obtain remarkably high CO₂ recovery and purity (99.99%). The significant advantage of the CCC process is that it can be easily retrofitted to existing systems and can handle the gas stream’s impurities. Different desublimation-based CCC technologies like Cryogenic packed bed, Anti sublimation, External cooling loop, CryoCell process and Novel low-cost CO₂ capture technology (NLCCT) are reported in the literature. The significant limitations of these processes are the continuous removal of the dry ice into storage tanks. For the efficient design of CCC systems, accurate prediction of the phase equilibria data and modeling of the frost formation is called for. This paper reviews the recently reported cryogenic desublimation technologies and analyses the various challenges in making them economically viable. The article also examines the different heat and mass transfer models employed to model CO₂ frost formation.

The use of membranes to capture CO₂ is a proven carbon capture technique. Gas separation membranes enhance the mole fraction of CO₂ in the feed gas. The membrane separation technique is low-cost because of its compact size, excellent energy efficiency, minimum environmental effect, simplicity of scale-up, fewer moving parts, moderate energy consumption, and ease of handling. Hybrid membrane cryogenic (HMC) and low-temperature membrane cryogenic (LTMC) are hybrid capture systems that combine the advantages of membrane and cryogenic techniques. In the HMC process, the flue gas is first pre-treated by the membrane process for CO₂ enrichment and the cryogenic process to capture the CO₂. In the LTMC process, low-temperature membrane units increase flue gas CO₂ concentration to 50%–75%, and a cryogenic process liquefies the rich CO₂ stream. Permeability and selectivity are the crucial parameters of the membrane which determine the CO₂ purity and recovery of capture. Most polymeric membranes have a trade-off of CO₂/N₂ selectivity (α_CO2/N2) and CO₂ permeability (P_CO2). The operating temperatures also impact membrane performance. An anti-trade-off effect was observed upon cooling down by increasing P_CO2 and α_CO2/N2. With increased P_CO2 and α_CO2/N2, sub-ambient temperature-based membrane cryogenic CO₂ capture techniques will lower power consumption and energy cost for CO₂ capture (CC). This review analyses the costs and energy requirements of various HMC and LTMC configurations for CO₂ capture. The study also examines the features of the different membranes used and the effect of operating and membrane parameters on the process performance.

Computational Fluid Dynamics analysis has emerged as a necessary tool for designing of turbomachinery. It helps to understand the various sources of inefficiency through investigation of flow physics of the turbine. In this paper, 3D turbulent flow analysis of a cryogenic turboexpander for small scale air separation was performed using Ansys CFX®. The turboexpander has been designed following assumptions based on meanlineblade generation procedure provided in open literature and good engineering judgement. Through analysis of flow field, modifications and further analysis required to evolve a more robust design procedure, have been suggested

The conceptual aircraft design and its integration with a combined cycle engine for hypersonic cruise at Mach 8 is documented in this paper. The paper describes the process taken to develop a hypersonic aircraft from a conceptual approach. The discussion also includes the design and CFD analysis of the integrated combined cycle engine. A final conceptual hypersonic transport aircraft with an integrated combined cycle engine was achieved through this study. According to the analysis carried out, the aircraft is able to take-off and land at the airports it is intended to be used and will be able to generate enough thrust to sustain hypersonic cruise at an altitude of 30 km.