Data centers rely on diverse cooling methods, categorized into mechanical refrigeration and natural cooling. Mechanical systems include air-cooled direct expansion (DX), air-cooled chilled water, water-cooled chilled water, and centralized cooling water systems. Natural cooling encompasses fresh air, plate heat exchange, rotary heat exchange, evaporative cooling, and liquid cooling.
Air-cooled DX Systems are traditional, with indoor units (compressor, evaporator) connected to outdoor condensers via refrigerant lines. Their simple design ensures reliability (no single point of failure). With fluoride pump energy saving (activating below 5°C), PUE in Zhejiang drops from ~1.71 to ~1.43.
Water-cooled Chilled Water Systems use centrifugal chillers and cooling towers, ideal for high heat loads. Winter free cooling via heat exchangers boosts efficiency (PUE ~1.43 in Zhejiang) but requires complex maintenance.
Air-cooled Chilled Water Systems skip cooling towers, suiting moderate loads. They use air-cooled chillers and offer winter natural cooling, with a typical PUE of ~1.48 in Northeast China.
Liquid Cooling directly targets high-density servers, using water, mineral oil, or fluorinated fluids. Immersion cooling (e.g., fluorinated fluids) excels in efficiency, avoiding traditional HVAC limitations.
Natural Cooling Technologies like fresh air (clean areas), plate exchangers (polluted environments), and evaporative cooling (dry climates) cut PUE by leveraging outdoor cold air, extending energy-saving periods.
