In high-density deployment scenarios, server chassis require multi-dimensional heat dissipation structure design to optimize heat conduction efficiency and airflow distribution to address the challenge of air cooling system performance degradation as power density increases. Core design strategies encompass five key areas: air duct optimization, fan upgrades, liquid cooling integration, redundancy mechanisms, and material innovation.
In traditional air cooling systems, the complex internal structure of the chassis can easily lead to turbulent airflow, creating heat dissipation dead zones. Modern designs utilize hot and cold aisle isolation technology to create a cool air intake area at the front of the chassis and a hot air exhaust area at the rear, creating a unidirectional airflow cycle. For example, some server chassis utilize a combination of vertical air scoops and horizontal manifolds to precisely direct cool air to high-heat load areas such as the CPU and GPU. The deflector design ensures even airflow coverage of the rear hard drives, addressing the rear heat dissipation challenges inherent in traditional layouts. Furthermore, optimizing the internal hardware layout of the chassis is crucial. By placing low-heat components such as hard drives and memory above and below the fan, the high air pressure characteristics of the dual-rotor fan allow air to flow through the memory, PCIe expansion cards, and ultimately through the GPU heat sink, completing the heat cycle.
High-density deployments place higher demands on fan performance. High-pressure fans, with their unique impeller design and high-efficiency motor drive, generate strong pressure to propel air smoothly through narrow ducts. For example, a hyperscale data center implemented high-pressure centrifugal fans, resulting in more uniform temperature distribution within the cabinets and significantly lower overall temperatures. Furthermore, by establishing a stable airflow direction, hot air is effectively prevented from backflowing into the server air intakes. When selecting a fan, comprehensive considerations include pressure parameters, air volume, noise control, and reliability. It is generally recommended to select a fan with appropriate static pressure to overcome duct resistance, and to calculate the required air volume based on the total server heat output and allowable temperature rise. Furthermore, fans with intelligent speed control can reduce speed during low loads, reducing noise and extending service life.
Liquid cooling technology, with its superior heat dissipation performance, has become a key solution for overcoming air cooling bottlenecks. Cold plate liquid cooling utilizes cold plates attached to heat-generating components such as CPUs and GPUs, allowing coolant to circulate within the cold plate to remove heat. Its advantages include high compatibility, low retrofit costs, and the absence of major modifications to existing computer rooms. Immersion liquid cooling completely immerses the server in an insulating coolant, transferring heat through the circulating coolant. Two-phase immersion liquid cooling utilizes the vapor generated by the boiling coolant on the surface of heat-generating components. This vapor condenses on the condenser, transferring heat to the facility's cooling water, significantly improving heat transfer efficiency.
Redundant cooling mechanisms are key to ensuring system reliability. By deploying redundant fans, the speed of the remaining fans automatically increases in the event of a single fan failure, maintaining stable airflow. For example, some server chassis feature louvers on the rear of the fans as backflow prevention devices. When a fan fails, the corresponding louver automatically closes to prevent backflow through the front louver and airflow loss. The system also increases the speed of other fans to replenish airflow in the failed channel, achieving zero-downtime maintenance. Furthermore, the use of high-reliability fan materials and bearing designs significantly extends fan life and reduces maintenance challenges.
Chassis materials and manufacturing processes also significantly impact heat dissipation efficiency. Highly thermally conductive materials such as copper and aluminum are widely used in heat sinks and cold plates to quickly transfer heat to the coolant or air. For example, the bottom of the CPU heat sink in some server chassis utilizes a rare metal with high thermal conductivity as the thermal medium. This low thermal resistance and excellent ductility prevent the cracking of ordinary thermal silicone from prolonged use, ensuring maintenance-free operation within the chassis' lifecycle. Furthermore, the chassis' internal heat sink utilizes an integrated molding process and a U-shaped heat pipe design to effectively reduce thermal resistance and improve heat transfer performance.
