Why Horizontal Multistage Pumps Are Revolutionizing Data Center Liquid Cooling Efficiency

With the advent of the 5G era and the development of IT technologies such as artificial intelligence and cloud computing, the scale of global data centers (DCs) has grown rapidly, which means more energy consumption, so energy-saving technologies are needed to improve system efficiency. The improvement of data center energy efficiency has curbed the rapid growth of energy demand, especially the reduction in power demand for cooling systems has partially offset the growth in power demand for IT equipment. However, the energy consumption of the cooling system accounts for about 30-50% of the energy consumption of a typical DC system, and there is great potential for improving the efficiency of the cooling system.

Natural cooling technologies such as loop heat pipes are an effective solution to reduce the power consumption of cooling systems. Loop heat pipes are passive heat transfer devices that can be used in different thermal regulation systems with remote radiators or heat sources. Loop heat pipe (also known as two-phase loop thermosyphon) systems have the advantages of high thermal efficiency, good reliability, and high cost performance. In particular, water pump-driven loop heat pipe systems are used for natural cooling in data centers, which undoubtedly have a higher energy efficiency ratio compared to air conditioners.

The energy consumption of compressors usually accounts for most of the cooling system, and the use of high-efficiency compressors can reduce the energy consumption of cooling systems. Magnetic levitation compressors have become a new choice due to their non-mechanical friction and oil-free characteristics. Based on the construction of new cooling systems and the significant efficiency improvements achieved in relatively small or ultra-large-scale DCs, it is very important to develop new cooling systems for data centers.

1.Water-cooled direct evaporative air conditioning system components (DX)

The water-cooled direct evaporative air conditioning system is shown in the figure below. The unit mainly consists of a frame, compressor, evaporator, condenser, electronic regulating valve, indoor fan, outdoor fan, unit control system, temperature and humidity sensor, plate heat exchanger (Freon and cooling water/ethylene glycol), outdoor cooling tower (dry cooler), cooling water (ethylene glycol) pipeline, circulating water pump, etc. The high-temperature gas of the refrigerant discharged by the compressor is condensed into liquid by cooling water in the indoor plate heat exchanger, and then throttled and reduced in pressure by the expansion valve to become a low-temperature gas-liquid mixture, and then flows into the indoor fin heat exchanger, absorbs the heat in the machine room, evaporates, and returns to the compressor to complete a refrigeration cycle; at the same time, the return air from the hot channel of the machine room is cooled and cooled after passing through the indoor evaporator, and the treated cold air is sent into the room by the air conditioning fan.

2.Air-cooled

The main difference between air-cooled and water-cooled direct evaporative air conditioning systems lies in the cooling method of the condenser. The indoor unit of the water-cooled direct evaporative air conditioning system is equipped with a water-cooled condenser, and the cooling water (ethylene glycol) is provided by the outdoor cooling tower (dry cooler), and the heat is exchanged through a plate heat exchanger (or shell and tube heat exchanger). The unit condenser and evaporator are both inside the indoor unit, and the refrigeration cycle system pipeline is short. The cooling water required by the condensers of all computer room air conditioning units can be put into one system, and the water pump provides power for the cooling water (ethylene glycol) circulation.

Compared with air-cooled direct evaporative air conditioning systems, water-cooled direct evaporative air conditioning systems have the following advantages:

• It avoids problems such as long refrigerant transportation distance and difficult oil return.
• The condensing temperature of the air conditioning unit is low, which improves the cooling efficiency.
• The initial investment cost is lower than that of air cooling and evaporative cooling.
• The cooling effect is good and it is suitable for medium and large data centers.

Liquid cooling has emerged as the dominant solution, with horizontal multistage centrifugal pumps becoming the unsung heroes of thermal management. Unlike vertical designs, these pumps deliver unparalleled stability in high-pressure, continuous-operation scenarios – a critical advantage for hyperscale facilities demanding 99.999% uptime.

• Ultra-high pressure transmission capacity--Multi-stage impeller series design (up to 12 stages) achieves 80-200 meters of head, easily coping with complex pipe network resistance.
• Minute-level maintenance efficiency--Horizontal disassembly and assembly structure supports bearing replacement in situ without disconnecting the pipeline. Google Oregon Data Center actual measurement shows that maintenance time is 70% less than that of vertical pumps, and a single pump saves 43 hours per year.
• Ultimate silent design--The damping base and dynamically balanced impeller suppress the noise below 65dB(A) (equivalent to the sound of daily conversation), meeting the stringent requirements of urban edge data centers. China Mobile Hangzhou Hub test shows that the vibration intensity is 40% lower than that of vertical pumps.

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