Normalized evaluation index of jet length and resistance for square diffuser shape optimization

Abstract

In public buildings, the energy consumption of HVAC system fans due to the resistance of the HVAC ducts accounts for approximately 20–40% of the total energy consumption of the building. This study focuses on the structural design of square diffusers in HVAC systems. By introducing the concept of a conversion coefficient for the diffuser jet length, a comprehensive evaluation index that is suitable for describing the performance of square diffusers is developed and improved upon. This study employs a combination of kriging surrogate modeling and multi-island genetic algorithm (MIGA) optimization to obtain the optimal structural parameters of the square diffuser. This study also analyzes the effects of different velocities on the square diffuser's resistance and jet length characteristics and conducts full-scale experimental verification of the square diffuser manufactured using 3D printing technology. The results show that the traditional square diffusers in ventilation and air-conditioning systems are optimized by using the Kriging model and multi-island genetic algorithm, resulting in a new type of square diffuser with the best parameters and a final reduction of 2.98 in the Square Diffuser Effective Index (SDEI). Through a comparative analysis of experimental data and numerical simulation results, the effectiveness and practicality of the proposed optimization method are demonstrated.