Computational investigation of the hexagonal honeycomb adsorption reactor for cooling applications

Abstract

Adsorption cooling is a sustainable technology, since it can utilize solar energy or waste heat, while employing substances without ozone depletion and global warming potential. The adsorption reactor design is determinant for the system performance. An underexplored geometry hitherto – the hexagonal honeycomb adsorption reactor – was numerically investigated. An in-house, validated, three-dimensional computational model based on unstructured meshes was employed. The Specific Cooling Power (SCP) and Coefficient of Performance (COP) were quantified for several geometrical and operational parameters. The cell inradius creates a dichotomy between SCP and COP, being 218.9 W/kg˙s and 0.356 for 1 mm, while being 80.4 W/kg˙s and 0.606 for 6 mm. The cell height influences prominently the SCP, being 159.5 W/kg˙s and 86.1 W/kg˙s for 5 mm and 30 mm, respectively. The fin thickness impacts mostly the COP, being 0.599 and 0.364 for 0.5 mm and 3 mm, respectively. Higher COP is achieved for higher evaporator, lower adsorption and lower condenser temperatures. Higher SCP is achieved for lower adsorption and condenser, and higher evaporator and desorption temperatures. Shorter cycles result in high SCP and low COP, whereas the inverse occurs for longer cycles. Aluminum heat exchanger yields 7.7% higher COP than copper. The results are discussed from a physical, as well as, an engineering perspective. • Hexagonal honeycomb reactor studied in the context of adsorption cooling. • Quantification of COP and SCP under various geometrical and operational parameters. • Geometrical and operational parameters are determinant for the reactor performance. • Adaptive cycle duration is highly useful for the regulation of system performance. • Aluminum heat exchanger yields 7.7% higher COP than copper.