最佳液体冷却：水冷散热系统

The ultimate liquid cooling: heat rejection into water

June 6, 2022 By Jacqueline Davis

译 者 说

有没有比风冷冷却塔更高效的散热方式？向自然水体散热的直流冷却技术正是uptime关注的节能散热方式之一。如果您的园区里正好有一条人工河流，恭喜您！您也可以实现更低PUE的自然冷却。

Uptime Institute PUE数据证明了过去10年，数据中心行业在不断提升能源效率方面取得了重要的进步。

Uptime Institute’s data on power usage effectiveness (PUE) is a testament to the progress the data center industry has made in energy efficiency over the past 10 years.

然而，自2018年开始，全球数据中心的平均PUE一直基本停滞在1.6的水平，仅仅略有改善。

However, global average PUEs have been largely stalling at close to 1.6 since 2018, with only marginal gains.

这很合理，为了使数据中心的平均PUE 显著提升，需要对大多数的制冷系统设备进行耗资巨大的整改从而提升设备运行效率，并且现时数据中心能源效率的提升已经接近物理规律的极限。

This makes sense: for the average figure to show substantial improvement, most facilities would require financially unviable overhauls to their cooling systems to achieve notably better efficiencies, while modern builds already operate near the physical limits of air cooling.

在液体制冷方面寻找突破

Looking to liquid

越来越多的数据中心运营商正在寻找直接液体冷却（DLC）的方法，以实现基础设施运营效率的下一次飞跃。

A growing number of operators are looking to direct liquid cooling (DLC) for the next leap in infrastructure efficiency.

但是，大规模由传统空气冷却转向液体冷却涉及到复杂的运营和供应链方面的挑战，即使是资源最丰富的技术组织也面临困难。

But a switch to liquid cooling at scale involves operational and supply chain complexities that challenge even the most resourceful technical organizations.

Uptime 了解到只有一家主流运营商使用直接液体冷却（DLC）作为标准做法：法国托管和云提供商 OVHcloud。这家公司是一个特例，它所提供的垂直集成基础设施使用定制的内部冷板和服务器设计。

Uptime is aware of only one major operator that runs DLC as standard: French hosting and cloud provider OVHcloud, which is an outlier with a vertically integrated infrastructure using custom in-house water cold plate and server designs.

数据中心直流冷却系统示意图

Schematic of a data center once-through system

在使用液体冷却时，冷却基础设施中一项经常被忽视的部分是散热。

When it comes to the use of liquid cooling, an often-overlooked part of the cooling infrastructure is heat rejection.

排入大气的热量是低能效的一项主要因素，不仅体现在能源使用方面，还体现在初始资本投资的增加和用于最坏情况（设计日）冷却需求的冗余配置。

Rejecting heat into the atmosphere is a major source of inefficiencies, manifesting not only in energy use, but also in capital costs and in large reserves of power for worst case (design day) cooling needs.

多年以来，一小部分数据中心一直在成功地使用水作为空调的散热系统。

A small number of data centers have been using water features as heat sinks successfully for some years.

一些设施不是通过水塔、风冷式冷水机或其他依赖环境空气的设备散热，而是使用闭式冷冻水回路，通过由开放式水环路冷却的热交换器排出热量。

Instead of eliminating heat through water towers, air-cooled chillers or other means that rely on ambient air, some facilities use the closed chilled water loop, which rejects heat through a heat exchanger that’s cooled by an open loop of water.

这些使用水冷散热系统的冷却设计扩展了水热特性的优势，从数据中心内部的热传输过程到设施外部的散热过程。

These cooling designs using water heat sinks extend the benefits of water’s thermal properties from heat transport inside the data center to the rejection of heat outside the facilities.

当然，用水进行散热的想法并不新鲜。

The idea of using water for heat rejection, of course, is not new.

这些系统被称为直流冷却水系统，并且因其在处理超高热负荷方面具有高效率和可靠性而广泛用于热电发电和制造行业。

Known as once-through cooling, these systems are used extensively in thermoelectric power generation and manufacturing industries for their efficiency and reliability in handling large heat loads.

由于 IT 基础设施相对体积较小，并且往往聚集在人口中心附近，而人口中心又往往位于靠近水的地方，Uptime 认为该方法在未来的数据中心建设项目中具有广泛的地理适用性。

Because IT infrastructures are relatively smaller and tend to cluster around population centers, which in turn tend to be situated near water, Uptime considers the approach to have wide geographical applicability in future data center construction projects.

Uptime 的研究已经确定了十多个数据中心站点，其中一部分由世界知名的运营商负责运营，并且广泛的使用水景作为散热系统。

Uptime’s research has identified more than a dozen data center sites, some operated by global brands, that use a water feature as a heat sink.

所有直流冷却设计都使用一些定制设备——目前对于数据中心而言，还没有具有规模化商业可行性的现成设计。

All once-through cooling designs use some custom equipment — there are currently no off-the-shelf designs that are commercially available for data centers.

尽管我们所研究的设施在规模、位置和一些工程选择上各不相同，但项目之间存在一些共性。

While the facilities we studied vary in size, location and some engineering choices, there are some commonalities between the projects.

直流冷却设计的项目在技术和商业上都取得了成功。始于 2021 年的能源价格危机，以及企业对可持续发展认证的热潮，提高了回报水平。

Once-through cooling projects have been a technical and a business success. The energy price crisis that started in 2021, and a corporate rush for sustainability credentials, have boosted the level of return

我们为这项研究采访过的运营商（他们都是托管服务提供商）认为他们的直流冷却设计项目在技术和商业上都取得了成功，实现了强大的运营绩效，并且增加了对于客户的吸引力。

Operators we’ve interviewed for the research (all of them colocation providers) considered their once-through cooling projects to be both a technical and a business success, achieving strong operational performance and attracting customers.

始于 2021 年的能源价格危机，结合企业热衷于宣称具有强大可持续发展能力，据报道这两样因素提高了相应投资的回报水平，甚至超过了原本预测的最乐观情况。

The energy price crisis that started in 2021, combined with a corporate rush to claim strong sustainability credentials, reportedly boosted the level of return on these investments past even optimistic scenarios.

将热量排入水体可实现全年稳定的 PUE，这意味着托管服务提供商可以相对之前相同的能源功率服务更大的 IT 负载。

Rejecting heat into bodies of water allows for stable PUEs year-round, meaning that colocation providers can serve a larger IT load from the same site power envelope.

另一个好处是能够降低数据中心的机房温度，例如“免费”从 64°F 到 68°F（18°C 到 20°C）：这不会带来 PUE 损失。

Another benefit is the ability to lower computer room temperatures, for example, 64°F to 68°F (18°C to 20°C) for “free”: this does not come with a PUE penalty.

低的送风温度有助于运营商最大限度地减少 IT 组件故障，并为未来的高性能服务器提供足够的冷却。

Low-temperature air supply helps operators minimize IT component failures and accommodate future high-performance servers with sufficient cooling.

如果水景具备自然流动或补充的属性，运营商还可以从其基础设施中消除对于冷水机组或者其他大型制冷设备的需求。或者这些系统可以作为备用。

If the water feature is naturally flowing or replenished, operators also eliminate the need for chillers or other large cooling systems from their infrastructure, which would otherwise be required as backup.

尽管如此，对于所产生的有利结果是否可以超过在设计和施工方面所需要的投资还远远未能确定，因为所有项目都涉及到超凡的工程工作和与之关联的各项成本问题。

Still, that these favorable outcomes outweigh the required investments were far from certain during design and construction, as all undertakings involved nontrivial engineering efforts and associated costs.

高级管理层所承诺的资助，对于这些项目获得批准并克服任何意想不到的困难显得至关重要。

Committed sponsorship from senior management was critical for these projects to be given the green light and to overcome any unexpected difficulties.

我们预测将会出现一个更成熟的市场

We predict a more mature market

受到我们研究案例得到的积极成果所鼓舞，Uptime 预计直流冷却设计将在未来引起更多关注。

Encouraged by the positive experience of the facilities we studied, Uptime expects once-through cooling to gather more interest in the future.

对于这种设计技术而言，一个更加成熟的市场将会把项目选址纳入考虑因素，而地方政府对于能源效率和可持续发展的要求也会是一个重要影响因子。

A more mature market for these designs will factor into siting decisions, as well as jurisdictional permitting requirements as a proxy for efficiency and sustainability.

通过“免费”低温操作，直流冷却设计还将帮助最大限度的提高未来直接液体冷却（DLC）技术的能源效率优势，从而创建端到端的液体冷却基础设施。

Once-through systems will also help to maximize the energy efficiency benefits of future DLC rollouts through “free” low-temperature operations, creating an end-to-end liquid cooling infrastructure.