Temperature chaining

Last updated

Temperature chaining can mean temperature, thermal or energy chaining or cascading. [1]

Contents

Temperature chaining has been introduced as a new concept at Datacentre Transformation [2] in Manchester by the company Asperitas [3] as part of a vision on a Datacentre of the Future. [4] It is a method of transforming electrical consumption in datacentres into usable heat. The concept is based on creating high temperature differences in a water based cooling circuit in a datacentre. The premise is that every system in a datacentre can be equipped with a shared water infrastructure which is divided into multiple stages with different temperatures. The different temperatures are achieved by setting up different liquid cooling technologies with different temperature tolerances in a serial cooling setup as opposed to a single parallel circuit. This creates high temperature differences with a low water volume. This results in a datacentre environment which is capable of supplying constant temperature water to a re-user, thus transforming the facility from an electrical energy consumer into a thermal energy producer.

History

Temperature or energy chaining is applied in heating systems where hydraulic designs allow for return loops and serial heaters. [5]

The temperature chaining principle is also used in refrigeration systems which adopt cascading circuits. [6] [7]

The Amsterdam Economic Board has presented the 4th generation of district heating networks which will adopt thermal cascading to increase flexibility and to make the district networks future proof. [8]

Within datacentres, the traditional approach towards the critical IT load is cooling. Temperature chaining works on the basic premise that the IT is a heating source. To harvest this heat, liquid cooling is used, which allows the application of hydraulic heating designs [5] to the datacentre.

Liquid cooling infrastructure in datacentres

Introducing water into the datacentre whitespace is most beneficial within a purpose-built set-up. This means that the focus for the design of the datacentre must be on absorbing all the thermal energy with water. This calls for a hybrid environment in which different liquid based technologies are co-existing to allow for the full range of datacentre and platform services, regardless of the type of datacentre.

The adoption of liquid cooled IT in datacentres allows for more effective utilisation or reduction of the datacentre footprint. This means that an existing facility can be better utilised to allow for more IT.

The higher heat capacity of liquids allows for more dense IT environments and higher IT capacity. With most liquid technologies, the IT itself becomes more efficient. This is caused by the reduced or eliminated dependence on air handling within the IT chassis. Individual components are cooled more effectively and can therefore be used with higher amounts of energy and closer to each other. When liquid penetrates the IT space, internal fans are reduced or completely eliminated which saves energy. This also reduces the emergency power requirements within the facility.

Liquid datacentre technologies

Liquid cooling technologies can be roughly divided into four different categories: cooling at the room, rack or chip level and immersion.

Computer Room Air Conditioning or Air Handlers (CRAC/CRAH) can be water cooled.

Indirect Liquid cooling (ILC) [9] involves water cooled racks with (active) rear door or in-row heat exchangers which are water cooled. The advantage of the active rear doors is that all the heat from air cooled IT is immediately absorbed by the water circuit when it leaves the rack which eliminates the need for CRACs, also in partial ILC implementations. This makes cooling systems very efficient, and supports limited efficiency on the IT itself by assisting ventilation.

Direct Liquid Cooling (DLC) [10] effectively cools parts of the IT with purpose built coolers which combine cold plates and pumps that are mounted directly onto the chips instead of a traditional heat sink. This generates energy efficiency on the IT side due to the reduced amount of fan energy. Although the water circuit captures all of the heat from the largest heat sources inside the chassis, this approach may still require CRAC units or combinations with ILC for rejection of thermal energy from the rest of the IT components.

Total Liquid Cooling (TLC) [11] completely immerses the IT components in liquid. There is hardly any energy loss and IT equipment is made very energy efficient, eliminating kinetic energy (fans) from being used by the IT. Since water conducts electricity, an intermediate dielectric substance is required which requires forced or convective transfer of heat. This dielectric can be oil or chemically based. The infrastructure and power advantages are maximised with this approach and the energy footprint is fully optimised.

Since there is no such thing as one solution for all, any platform should be designed with the optimal technology for its different elements. Therefore, each part of a platform should be set up with a mix of optimised technologies. For example, storage environments are least suitable to be cooled directly by liquid due to the low energy production and the common dependency on moving parts. These can be set up in water cooled racks. High volumes of servers which require the least maintenance can best be positioned in a Total Liquid Cooling environment. Varying specialised server systems which require constant physical access are best situated in Direct Liquid Cooled environments.

A prerequisite for each technology before it can be applied in a temperature chaining scenario is a level of control (by PLC) over its own cooling infrastructure and compatibility in the sense of fittings and liquid compatibility.

Temperature chaining

Example of temperature chaining in a datacentre Post - Whitepaper DC of the Future - Temperature Chaining.jpg
Example of temperature chaining in a datacentre

By adopting a hybrid model, systems can be connected to different parts of a cooling circuit with different temperatures. Each liquid technology has different temperature tolerances. Especially where the liquid penetrates the chassis, the stability of temperatures becomes less of a concern. Therefore, different technologies can be set up in an optimised order of tolerance to allow a multi-step increase in temperature within the cooling circuit.

This means that the water infrastructure becomes segmented. Instead of feeding each cooling setup in a parallel infrastructure, the inlets of different technologies or different parts of the infrastructure are connected to the return circuit of another part of the infrastructure. In essence, the output of a liquid cooled rack should not be routed to a cooling installation, but to a different type of liquid cooling environment. By chaining the segmented liquid circuits in larger environments, very high return temperatures can be achieved, which enables the practical and effective reusability of thermal energy and decreases investments needed to make large scale heat reuse a viable option.

The different liquid technologies can be applied with different temperature levels. There is a difference between normal optimised environments and more “extreme” environments where the solutions and IT equipment are more compatible or specialised for high temperature operation.

Example of temperature tolerances for different technologies
TechnologyInlet rangeOutlet rangeMaximum delta/rack
NormalExtremeNormalExtreme
CRAC (generic)6-18 °C21 °C12-25 °C30 °CN/A
ILC (U-Systems)18-23 °C28 °C23-28 °C32 °C12 °C
DLC (Asetek)18-45 °C45 °C24-55 °C65 °C15 °C
TLC (Asperitas)18-40 °C55 °C22-48 °C65 °C10 °C

Liquid Temperature Chaining can be implemented by adopting intermediate cooling circuits with different temperature ranges. Segmented environments can be connected with supply and return loops, mixing valves and buffer tanks to stabilise and optimise the return temperatures and volumes of each individual segment.

A major advantage of this strategy is the fact that temperature differences (dT) within a cooling circuit can be drastically increased. This reduces the volume of liquid required in a facility and reduces the cooling overhead installations.

After all, it is much more efficient to cool a large dT in a small volume of water than a small dT in a large volume of water.

Heat reuse infrastructure example

This example only provides insight into optimised liquid infrastructures to explain the concepts of Temperature Chaining and how different liquid technologies can fit into this concept. For simplification purposes, there are no redundant scenarios outlined. Return loops, buffer tanks and intermediate pumps to deal with volumetric and pressure aspects within different stages are not detailed.

The open circuit heat reuse infrastructure is the most sustainable infrastructure by far. In this situation, the datacentre receives water of a certain temperature and all the heat generated by the IT equipment is delivered to another user with this water circuit. This means that the facility does not only reject the heat, but also the water which contains the heat to allow an external party to transport and use the warmed-up liquid. This results in a complete lack of cooling installations and the datacentre effectively acts like a large water heater. Water flows into the datacentre and comes out at high temperatures.

The ILC racks in this setup effectively function as air handlers which maintain the entire room temperature and absorb all thermal energy leakage from the DLC and TLC environments.

Temperature chaining concept for heat reuse Temperature chaining for reuse.png
Temperature chaining concept for heat reuse

Micro infrastructure example

Micro datacentre temperature chaining for reuse Temperature chaining micro facility.png
Micro datacentre temperature chaining for reuse

In smaller footprints, temperature chaining can be achieved by creating a small water circuit with a mixing valve and buffer tank. This allows the output of the liquid installation to be routed back to the cooling input to gradually increase the cooling circuit and achieve a constant high output temperature. Although this is not the multi-stage approach, it is a common and well proven practice for achieving constant input or output temperatures.

The advantage of this approach is the compatibility with variable input temperatures which are common with dry cooling installations.

Related Research Articles

<span class="mw-page-title-main">Heating, ventilation, and air conditioning</span> Technology of indoor and vehicular environmental comfort

Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR.

<span class="mw-page-title-main">Heat exchanger</span> Equipment used to transfer heat between fluids

A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air. Another example is the heat sink, which is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant.

<span class="mw-page-title-main">Thermoelectric cooling</span> Electrically powered heat-transfer

Thermoelectric cooling uses the Peltier effect to create a heat flux at the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC) and occasionally a thermoelectric battery. It can be used either for heating or for cooling, although in practice the main application is cooling. It can also be used as a temperature controller that either heats or cools.

<span class="mw-page-title-main">Solar water heating</span> Use of sunlight for water heating with a solar thermal collector

Solar water heating (SWH) is heating water by sunlight, using a solar thermal collector. A variety of configurations are available at varying cost to provide solutions in different climates and latitudes. SWHs are widely used for residential and some industrial applications.

<span class="mw-page-title-main">Evaporative cooler</span> Device that cools air through the evaporation of water

An evaporative cooler is a device that cools air through the evaporation of water. Evaporative cooling differs from other air conditioning systems, which use vapor-compression or absorption refrigeration cycles. Evaporative cooling exploits the fact that water will absorb a relatively large amount of heat in order to evaporate. The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapor (evaporation). This can cool air using much less energy than refrigeration. In extremely dry climates, evaporative cooling of air has the added benefit of conditioning the air with more moisture for the comfort of building occupants.

<span class="mw-page-title-main">Computer cooling</span> The process of removing waste heat from a computer

Computer cooling is required to remove the waste heat produced by computer components, to keep components within permissible operating temperature limits. Components that are susceptible to temporary malfunction or permanent failure if overheated include integrated circuits such as central processing units (CPUs), chipsets, graphics cards, hard disk drives, and solid state drives.

<span class="mw-page-title-main">Phase-change material</span> Substance with high latent heat of melting or solidifying

A phase-change material (PCM) is a substance which releases/absorbs sufficient energy at phase transition to provide useful heat or cooling. Generally the transition will be from one of the first two fundamental states of matter - solid and liquid - to the other. The phase transition may also be between non-classical states of matter, such as the conformity of crystals, where the material goes from conforming to one crystalline structure to conforming to another, which may be a higher or lower energy state.

<span class="mw-page-title-main">Thermal management (electronics)</span> Regulation of the temperature of electronic circuitry to prevent inefficiency or failure

All electronic devices and circuitry generate excess heat and thus require thermal management to improve reliability and prevent premature failure. The amount of heat output is equal to the power input, if there are no other energy interactions. There are several techniques for cooling including various styles of heat sinks, thermoelectric coolers, forced air systems and fans, heat pipes, and others. In cases of extreme low environmental temperatures, it may actually be necessary to heat the electronic components to achieve satisfactory operation.

Renewable heat is an application of renewable energy referring to the generation of heat from renewable sources; for example, feeding radiators with water warmed by focused solar radiation rather than by a fossil fuel boiler. Renewable heat technologies include renewable biofuels, solar heating, geothermal heating, heat pumps and heat exchangers. Insulation is almost always an important factor in how renewable heating is implemented.

Solar air conditioning, or "solar-powered air conditioning", refers to any air conditioning (cooling) system that uses solar power.

<span class="mw-page-title-main">Air source heat pump</span> Most common type of heat pump

An air source heat pump (ASHP) is a heat pump that can absorb heat from air outside a building and release it inside; it uses the same vapor-compression refrigeration process and much the same equipment as an air conditioner, but in the opposite direction. ASHPs are the most common type of heat pump and, usually being smaller, tend to be used to heat individual houses or flats rather than blocks, districts or industrial processes.

<span class="mw-page-title-main">Wax thermostatic element</span>

The wax thermostatic element was invented in 1934 by Sergius Vernet (1899–1968). Its principal application is in automotive thermostats used in the engine cooling system. The first applications in the plumbing and heating industries were in Sweden (1970) and in Switzerland (1971).

Free cooling is an economical method of using low external air temperatures to assist in chilling water, which can then be used for industrial processes, or air conditioning systems. The chilled water can either be used immediately or be stored for the short- or long-term. When outdoor temperatures are lower relative to indoor temperatures, this system utilizes the cool outdoor air as a free cooling source. In this manner, the system replaces the chiller in traditional air conditioning systems while achieving the same cooling result. Such systems can be made for single buildings or district cooling networks.

<span class="mw-page-title-main">Photovoltaic thermal hybrid solar collector</span>

Photovoltaic thermal collectors, typically abbreviated as PVT collectors and also known as hybrid solar collectors, photovoltaic thermal solar collectors, PV/T collectors or solar cogeneration systems, are power generation technologies that convert solar radiation into usable thermal and electrical energy. PVT collectors combine photovoltaic solar cells, which convert sunlight into electricity, with a solar thermal collector, which transfers the otherwise unused waste heat from the PV module to a heat transfer fluid. By combining electricity and heat generation within the same component, these technologies can reach a higher overall efficiency than solar photovoltaic (PV) or solar thermal (T) alone.

<span class="mw-page-title-main">Hot water storage tank</span> Tank used for storing hot water for heating or domestic use

A hot water storage tank is a water tank used for storing hot water for space heating or domestic use.

iDataCool is a high-performance computer cluster based on a modified IBM System x iDataPlex. The cluster serves as a research platform for cooling of IT equipment with hot water and efficient reuse of the waste heat. The project is carried out by the physics department of the University of Regensburg in collaboration with the IBM Research and Development Laboratory Böblingen and InvenSor. It is funded by the German Research Foundation (DFG), the German state of Bavaria, and IBM.

<span class="mw-page-title-main">Radiant heating and cooling</span> Category of HVAC technologies

Radiant heating and cooling is a category of HVAC technologies that exchange heat by both convection and radiation with the environments they are designed to heat or cool. There are many subcategories of radiant heating and cooling, including: "radiant ceiling panels", "embedded surface systems", "thermally active building systems", and infrared heaters. According to some definitions, a technology is only included in this category if radiation comprises more than 50% of its heat exchange with the environment; therefore technologies such as radiators and chilled beams are usually not considered radiant heating or cooling. Within this category, it is practical to distinguish between high temperature radiant heating, and radiant heating or cooling with more moderate source temperatures. This article mainly addresses radiant heating and cooling with moderate source temperatures, used to heat or cool indoor environments. Moderate temperature radiant heating and cooling is usually composed of relatively large surfaces that are internally heated or cooled using hydronic or electrical sources. For high temperature indoor or outdoor radiant heating, see: Infrared heater. For snow melt applications see: Snowmelt system.

The Glossary of Geothermal Heating and Cooling provides definitions of many terms used within the Geothermal heat pump industry. The terms in this glossary may be used by industry professionals, for education materials, and by the general public.

<span class="mw-page-title-main">Immersion cooling</span> IT cooling practice

Immersion cooling is an IT cooling practice by which complete servers are immersed in a dielectric, electrically non-conductive fluid that has significantly higher thermal conductivity than air. Heat is removed from a system by putting the coolant in direct contact with hot components, and circulating the heated liquid through heat exchangers. This practice is highly effective because liquid coolants can absorb more heat from the system, and are more easily circulated through the system, than air. Immersion cooling has many benefits, including but not limited to: sustainability, performance, reliability and cost.

The low-temperature distillation (LTD) technology is the first implementation of the direct spray distillation (DSD) process. The first large-scale units are now in operation for desalination. The process was first developed by scientists at the University of Applied Sciences in Switzerland, focusing on low-temperature distillation in vacuum conditions, from 2000 to 2005.

References

  1. "Cascaderen – DatacenterWorks". datacenterworks.nl (in Dutch). Retrieved 2018-02-12.
  2. Communications, Angel Business. "DATACENTRE TRANSFORMATION MANCHESTER". www.dtmanchester.com. Retrieved 2017-07-25.{{cite web}}: |first= has generic name (help)
  3. "Asperitas". asperitas.com. Retrieved 2017-07-25.
  4. "The datacentre of the future by Asperitas – Asperitas". asperitas.com. Retrieved 2017-07-25.
  5. 1 2 "Hydraulics in building systems". Siemens. 2017-07-04.
  6. US 3733845,Lieberman, Daniel,"CASCADED MULTICIRCUIT, MULTIREFRIGERANT REFRIGERATION SYSTEM",published May 22, 1973
  7. US 7765827,Schlom, Leslie A.&Becwar, Andrew J.,"Multi-stage hybrid evaporative cooling system",published August 3, 2010
  8. AmsterdamEconomicBoard (2016-02-22). "Presentatie 4TH GENERATION THERMAL NETWORKS AND THERMAL CASCADING".{{cite journal}}: Cite journal requires |journal= (help)
  9. "ColdLogik Rear of Cabinet Cooling Solution | USystems". www.usystems.co.uk. Retrieved 2017-07-25.
  10. "Data Center, Server, and PC Liquid Cooling - Asetek". www.asetek.com. Retrieved 2017-07-25.
  11. "AIC24 – Asperitas". asperitas.com. Retrieved 2017-07-25.