No abstract

CO 2 hydrate can be used as an alternate cooling substance in air-conditioning systems to minimize the use of traditional refrigerants, such as HFCs and HCFCs. A novel CO 2 hydrate-based refrigeration system with a function of cold energy storage was designed and investigated, using tetrahydrofuran (THF) as the thermodynamic promoter. Coefficient of performance (COP) of this system was calculated based on the simulation results. Effects of various operation parameters were also studied closely. The cold storage operation was then designed to investigate the energy storage ability of the current system. Results show that the system COP is 6.8, which is the major strength of this novel system. Because of the energy intensive process of CO 2 compression, the work imposed on elevating the gas pressure was considerable. A search for more appropriate additives or alternate guest substances should be conducted. In addition, compressor efficiency and pump efficiency are both critical for improving the energy efficiency. Enhanced refrigeration performance can also be realized at higher hydrate mass fraction. In addition, two different cold energy storage operation strategies were obtained. This research is of great significance to the in-depth development of hydrate-based refrigeration and cold energy storage system. The proposed system might contribute to minimizing the use of conventional coolants and realizing peak load shifting in the near future.

No abstract

No abstract

Carbon capture and storage (CCS) is regarded as the most efficient approach in handling the global warming crisis. MEA-based CO 2 capture is a well-developed chemical absorption method with a long period of industrial application. A novel hydrate-based gas separation (HBGS) method, with a wide range of advantages, has recently received special attention from researchers. In this study, two different CO 2 separation processes were simulated utilizing Aspen Plus software. The feasibility of both processes was validated, and the process energy consumption and exergy loss were also compared at the same flue gas condition. Some efforts have also been made to investigate the effects of different operation parameters on the process energy efficiency. Results show that the first law efficiency of the MEA-based CO 2 separation system is 88.19% and the second law efficiency of the system is 38.32%, while the corresponding values of the hydrate-based separation system are 74.15% and 38.85%, respectively. Cooling of the lean amine solution and the regeneration process occupy the largest portion of exergy loss in the MEA separation system. In the hydration separation, the flue gas compression and cooling are the major causes for exergy loss.