Heat exchange of a SiO2/water nanofluid in 3D printed lattice channels with differently staggered Kagome structures

In this study, a lattice channel crossed by a SiO2 water-based nanofluid is proposed as a technique to enhance heat transfer. Applications include civil and industrial heat exchangers, with a focus on improving energy efficiency in Nearly Zero Energy Buildings. The channel is 80 mm long, 5 mm in height and 15 mm in width. Uniform heat flux is provided. The unit cell is the Kagome type. Four configurations are studied, identified by the cell repetition in the flow direction, porosity and pillar diameter are kept constant. Heat exchange with the nanofluid is compared to a smooth duct with water and a water-glycol mixture. Flow rates range from 0.3 to 4.0 l/min with the working fluids entering at 20°C. The cooling efficiency is calculated via the index Nu/λ1/3. Results for SiO2 show that the reticular duct, when compared with water, reaches an increase in heat exchange of 15-20% for flow rates up to 1 l/min. In terms of energy efficiency, the trabecular geometries match the smooth duct at low flow rates, but achieve over 60% higher heat rejection. The waterglycol mixture outperforms the smooth duct in each configuration, both in thermal dissipation and thermal efficiency, reaching values six times higher.