Immersion cooling and heat storage

高性能计算机使用大量的能量来保持冷却和高效运行。英国的建筑物需要大量的能源来保持居住者的温暖。今天，供暖和制冷的能源是碳密集型的，在全国范围内，供暖和制冷的供应占英国温室气体排放的三分之一。冷却HPC系统产生的热量可以用于其他地方的空间加热，而储热器可以储存多余的热量，在需要时回收。该提案试图做到这一点：高效冷却高性能计算系统，并研究将由此产生的多余热量储存在被淹没的煤矿中——英国过去采矿业的遗产资产，作为零碳热量储存，为零碳的未来服务。在这里，我们研究了结合互补能源需求的可持续能源潜力-在不以地球为代价的情况下研究社会能源需求。目前英国的大型高性能计算系统都使用直接液体冷却（DLC），冷却液通过管道输送到计算节点内的散热器上，热量被提取出来，然后通过热交换器交换，然后释放到大气中。这些系统可以消耗数兆瓦的电力。以前的空气冷却系统效率更低。浸没式冷却是技术的自然发展，它将特别适应的服务器完全浸入传热液体中，通常是矿物油，可以从所有组件（不仅仅是cpu）中去除热量，简化服务器设计（没有风扇，热管和减少隐含的二氧化碳）。然后在更高的温度下从系统中提取热量。该技术仅使用5%的电力来处理废热，比DLC系统的20%和风冷系统的40% -100%要好得多，从而节省了大量电力。目前的英国HPC数据中心还没有使用这种相对较新的技术的任何直流经验，因此它被视为在新的HPC系统中采用的重大风险。因此，我们建议在杜伦大学的数据中心安装一个商用浸入式冷却箱（该数据中心也托管EPSRC BEDE N8 Tier-2系统）。这个浸入式测试平台系统将成为一个国家测试设施，供其他数据中心的工作人员访问以获得这项技术的经验，并供供应商展示他们的服务器技术。我们将分析该水箱内托管的工具包的性能，并调查流体温度和服务器能耗等属性。浸没式冷却的另一个好处是废热比传统系统处于更高（更可用）的温度。Durham是此类设施的理想地点，目前拥有国家ExCALIBUR硬件和支持软件系统以及一级和二级设施。我们进一步建议研究数据中心余热再利用，通过调查在数据中心站点下方废弃和淹水煤矿工作中存储HPC余热。通过储存余热，可以在需要时重新使用。这需要在矿井工作中钻几个钻孔来抽取水，增加或减少热量，然后将其重新注入矿井。简而言之，我们将研究将矿井作为热电池。这个提议很及时，因为它与大学目前在校园内安装热网的计划非常吻合。该场地将被用作生活实验室和其他潜在系统的范例。

High Performance Computers use substantial quantities of energy to keep them cool and operating efficiently. Buildings in the UK require substantial quantities of energy to keep their occupants warm. Today, energy for heating and cooling is carbon intensive, and nationally the supply of heat and cooling is responsible for 1/3 of the UK's greenhouse gases. Heat from cooling a HPC system can be used for space heating elsewhere, and heat storage can store excess heat, retrieving it when required. This proposal seeks to do just that: efficient cooling of HPC systems, and investigating storing the resulting excess heat in flooded coal mines - legacy assets from the UK's mining past acting as carbon-zero heat stores for a zero-carbon future. Here we examine the sustainable energy potential of combining complimentary energy demands - examining societal energy needs without costing the Earth.Current UK large HPC systems all use direct liquid cooling (DLC), where a cooling fluid is piped onto heat sinks within compute nodes, heat extracted and then exchanged via a heat exchanger before being released into the atmosphere. These systems can consume multiple Megawatts of power. Previous air-cooled systems were even less efficient.Immersion cooling is the natural progression in technology which involves fully immersing specially adapted servers in a heat transfer liquid, typically a mineral oil, which removes heat from all components (not just CPUs), simplifying server design (no fans, heat pipes and reduced embodied CO2. Heat is then extracted from the system at higher temperature. This technology uses as little as 5% of power for dealing with waste heat, much better than the ~20% for DLC systems and 40-100% for air-cooled systems, yielding a significant power saving.Current UK HPC data centres do not have any direct current experience with this relatively new technology, and therefore it is seen as a significant risk for adoption in new HPC systems.We therefore propose installing a commercial immersion cooling tank in Durham University's the data centre (which also hosts the EPSRC BEDE N8 Tier-2 system). This immersion test bed system will become a national testing facility for other data centre staff to visit to gain experience with this technology, and for vendors to demonstrate their server technologies. We will analyse the performance of kit hosted within this tank, and investigate properties such as fluid temperature and server energy consumption. A further benefit of immersion cooling is that the waste heat is at a higher (more usable) temperature than from conventional systems. Durham is the ideal location for such facility, currently hosting national ExCALIBUR hardware and enabling software systems and both Tier-1 and Tier-2 facilities.We furthermore propose to study data centre waste heat reuse, by investigating storing HPC waste heat in the abandoned and flooded coal mine workings beneath the data centre site. By storing the waste heat, it can be reused when required. This requires drilling several boreholes into the mine workings to abstract the water, add/subtract heat to it, and re-inject it back to the mine. In short, we would be investigating using the mine workings as a heat battery.This proposal is timely, since it fits well with the university's current plan to install a heat network across its campus.The site would be used as a living lab and exemplar for other potential systems.