Optimizing heat transfer in solar collectors using cone-perforated channels: A 3D numerical analysis

This research explores enhancing the efficiency of a solar air heater (SAH) by integrating cone-perforated channels as roughness features on the absorber plate. Two configurations are examined: parallel-flow cone-perforated (PC) and inclined-flow cone-perforated (IC). Three diameters (20 mm, 30 mm, and 40 mm) for each configuration are tested. The PC configuration aligns the plates parallel to the flow, while the IC configuration arranges them at an incline. These configurations are labeled as PC20, PC30, PC40, IC20, IC30, and IC40, respectively. The model’s accuracy is validated by comparing calculated outcomes with experimental data. The Realizable k-epsilon turbulence model shows a favorable correspondence between the computed and observed results. Mass flow rate is varied from 0.022 to 0.045 kg/s to assess its impact on SAH performance. The cone-perforated channels significantly affect thermal performance, with inclined configurations (IC20, IC30, IC40) enhancing heat transfer efficiency more than parallel configurations (PC20, PC30, PC40) due to increased turbulence. Friction factor analysis shows increased resistance with narrower passages, especially in smaller diameters (PC20, IC20). Convective heat transfer analysis displays higher temperatures and Nusselt numbers in smaller diameter configurations, with enhancements from 6.09 % to 43.53 % compared to smooth ducts. Despite higher Nusselt numbers, parallel-flow cone-perforated plate absorbers exhibit lower thermo-hydraulic performance parameter values due to higher friction factors. In contrast, inclined-flow cone-perforated plate absorbers (IC40) demonstrate higher thermo-hydraulic performance, attributed to enhanced heat transfer and efficient airflow, making IC40 configurations more favorable for overall thermal–hydraulic performance.