Exploring the feasibility of next-generation CO2-based adsorption cooling systems using different adsorbent reactor configurations

• Published in: Energy conversion and management 2023-08, Vol.289, p.117181, Article 117181
• Main Authors: Gautam, Chaudhary, Anupam, Sahoo, Satyabrata
• Format: Article
• Language: English
• Subjects: administrative management; Adsorbent reactor; adsorbents; adsorption; Adsorption cooling; Carbon dioxide; Cooling capacity; COP; desorption; energy conversion; geometry; Optimization; Refrigeration; temperature
• ISSN: 0196-8904
• DOI: 10.1016/j.enconman.2023.117181

•4-Bed CO2-based adsorption cooling system is analyzed with various sorbent reactors.•Variable aspect ratios of cylindrical reactors with longitudinal fins are explored.•The study is carried out for subcritical and transcritical cyclic operations.•Results show system performance is strongly dependent on reactor geometry.•23–98 % COP improvement is achieved during transcritical and subcritical operations. The present investigation expounds on the effects of the reactor geometry, cycle time and heating/cooling fluid temperatures on the performance of a 4-bed CO2 adsorption cooling system. Cylindrical adsorbent reactors of varying aspect ratios (AR) with an optimum number of internal longitudinal fins and non-finned reactors are compared. The study confirms the substantial effect of reactor configuration on the system COP, specific cooling effect (SCE) and power, energy interactions during various processes and the total cycle time (TCT), which the equilibrium or lumped system analysis fails to predict. An increment of 98 % and 189 % in system COP and SCE is attained by varying the aspect ratio of the reactor with fins under subcritical operations. In continuation, a reduction of 41 % in TCT is observed. The study confirms the optimum adsorption/desorption time for which the COP and SCE are maximum, especially for higher AR reactors. It is noteworthy that proper selection of reactor aspect ratio results in a better system COP, even at lower heating fluid temperatures. During the transcritical operations, an increment of 23 % in COP and 6 % in SCE is achieved for a gas cooler exit temperature of 35 °C. Moreover, the reactor configuration also affects the optimum gas cooler pressure for the transcritical cycle, like the gas cooler exit temperature. One of the crucial observations is that, for a given combination of reactor configuration, heating/cooling fluid temperatures, and operating pressures, there exists a minimum cycle time below which a cyclic steady-state condition is impossible to achieve. During the subcritical and transcritical operations, a maximum COP of 0.1 and 0.052 is achieved for the proposed adsorption chiller configuration, respectively.