Swirl diffuser shape optimization based on a comprehensive evaluation index for both winter and summer conditions

The energy consumption of buildings in China is equivalent to 947 million tons of standard coal, and heating, ventilation and air conditioning (HVAC) systems constitute approximately 65% of the total consumption. Swirl diffusers rely on components such as vortex generators or swirl blades to generate a rotational jet that increases the axial airflow to induce swirling. In this study, the performance of swirl diffusers in HVAC systems was examined. A new comprehensive evaluation index is provided to evaluate the performance of a swirl diffuser during winter. An optimization-based design process including structural parameterization, flow field simulation, establishment of kriging surrogate models and intelligent optimization was developed. The optimized structural parameters of a swirl diffuser were thus obtained. Finally, three-dimensional printing technology was employed to print the swirl diffuser, and experiments were conducted to validate the findings. Based on the Kriging surrogate model and multi-island genetic algorithm results, the positions and shapes of the guide vanes of traditional swirl diffusers used in HVAC systems can be optimized. Moreover, the air diffuser effective index and swirl diffuser effective index calculated using the optimal parameters were reduced by 55.93% and 74.7%, respectively, compared with those of traditional swirl diffusers.