# Optimization of Airflow Organization in Bidirectional Air Supply Data Centers in China
## 1 Introduction  
Data centers, serving as the core infrastructure of the digital industry, constitute a critical foundation for digital economic development [1]. With the accelerated advancement of emerging technology sectors, including 5G networks, cloud computing, and big data, data center scales continue to expand significantly. Projections indicate that by the end of 2025, China's data center rack inventory will grow to 14 million racks, accompanied by an electricity consumption reaching 120 billion kWh [2]. The safe and continuous operation of data centers relies on cooling systems to remove heat from server rooms. Studies indicate that cooling systems account for up to 40% of a data center's total energy consumption [3]. In recent years, new technologies like liquidcooling and natural cooling have been increasingly adopted to address the high energy consumption of cooling systems, owing to their significant energy-saving potential [4; 5; 6]. However, traditional air cooling methods remain dominant in existing data center facilities. The fundamental requirement for a 24/7 uninterrupted operation imposes stringent reliability demands on cooling systems. Furthermore, the implementation of new technologies is constrained by local environmental conditions and substantial initial investment costs for large-scale retrofits. Consequently, energy efficiency improvements in existing data centers continue to focus primarily on optimizing current airflow management systems [7]. These advanced cooling technologies are currently more suitable for newly constructed large-scale data center projects. The extended cooling path in air-cooled systems often leads to airflow distribution issues, including uneven air supply, imbalance between cooling supply and demand, and cooling air loss, all of which reduce the energy efficiency of air conditioning systems [8; 9]. Furthermore, as power density per rack continues to rise, the mixed deployment of various high-power IT equipment results in uneven heat load distribution both between and within racks. Under conventional air supply methods, insufficient cooling in high heat flux areas leads to elevated ambient temperatures, jeopardizing data center operational safety [10]. Operations personnel typically address local hotspots by either lowering supply air temperatures or increasing airflow rates, which further escalates cooling system energy consumption [11]. Therefore, optimizing airflow distribution to maximize cooling effectiveness is of paramount importance for ensuring both energy efficiency and operational safety in data centers [12]. Research on data center airflow optimization has primarily focused on three key aspects: improving airflow distribution uniformity, balancing airflow supply and demand, and reducing airflow losses [13]. To enhance airflow distribution uniformity, researchers have commonly employed strategies such as optimizing air conditioning unit layouts [14] and adjusting plenum geometric parameters [15; 16; 17]. Numerical simulations conducted by [PERSON] demonstrated that arranging air conditioning units perpendicular to server rows significantly improves airflow uniformity through perforated floors while reducing hot air recirculation at the end racks and cold air bypassing at the middle racks [18]. [PERSON]'s research further identified optimal plenum height ranges for different configurations: 1.0-1.2 m for open cold aisle designs, 0.6-0.8 m for cold aisle containment systems, and 0.4-0.6 m for hot aisle containment systems [19]. Some studies have proposed installing baffles in plenums to address insufficient airflow near air conditioning units [20], though these solutions introduce spatial constraints, increased airflow resistance, and potential maintenance challenges that limit their practical application. In addressing the airflow supply-demand balance, [PERSON] developed variable airflow panels installed beneath perforated floors that utilize pressure differentials between hot and cold aisles to regulate cooling delivery to different zones [21].