Thermal management requirements for edge computing

Edge computing requires several variables to be considered and an advanced climate control solution.

By Hans Baumann July 11, 2017

Edge computing houses data processing capability at or near the "edge" of a network facility. Usually servers are contained in a micro data center, with as few as one or two enclosures. Data which is mission-critical, such as a component malfunction or a software defect, is captured and available in real-time on-site. Edge computing is valuable in capturing bandwidth-intensive and latency-sensitive data for analysis, lowering operating costs and improving energy efficiency. Lower-priority data can be sent to the cloud or to a remote data center.

Companies are recognizing the importance of incorporating edge computing into their processes. However, a basic rack-mounted enclosure is still a challenge. In edge computing, server rack density and small footprints are key components to provide the near-user computing data. However, power consumption of a server rack is converted to heat, deadly to IT systems. And the smaller the space, the more the temperature rises. Thus, thermal safety is a paramount priority. 

Checklist of requirements for edge cooling

To determine the correct cooling solution for an edge computing microcenter, and prepare a plan that allows for correct sizing of the center, assess the distinct obstacles for edge computing.

Of all the concerns for an edge data center, cooling capacity consistently rates as a primary focus. A requirements checklist includes:

  • Select a climate control system that is well-matched to the heat output of the edge data center
  • Provide adequate airflow to each server rack
  • Assure operational reliability of the cooling and redundancy system
  • Maintain constant acceptable levels of temperature and humidity
  • Have options for scalability at the rack level and at the edge data center as a whole.

Evaluating the variables in edge computing

Heat dissipation and the inherent heat problems in edge computing require modular climate control systems. An energy-efficient and advanced climate control and cooling concept for edge computing takes these variables into account:

  • Temperature
  • Humidity
  • The velocity and pressure of airflows
  • Heat losses of the installed components.

Consider these fundamental criteria and variants in the design phase:

  • What type of liquid cooling package (LCP) cooling system should be installed? Whether or not a water- or refrigerant-based system is used can depend on the environment and the availability of a water supply.
  • Will the amount of racks and enclosures require hot and cold aisles? Cold aisle containment usually requires a raised floor. If a space is being retrofitted to accommodate enclosure racks, this design consideration may influence the decision.
  • What average temperatures should be maintained in the racks? It is still widely accepted that racks should be maintained at a cooler temperature, no more than 68 to 72°F. The setpoint temperature required depends in part on the heat output calculations for the rack enclosure. With densely-populated edge centers, additional cooling power may be needed to offset the higher heat loads.
  • What is the volumetric flow rate of cooled air required? Calculating the airflow requirement for each center depends on the rack requirements to design an efficient airflow strategy. Rack, inline, or a combination may be the correct solution.
  • What are the ambient conditions? Temperature extremes in either direction will affect the energy required to maintain an acceptable environment for the racks. The degree to which ambient temperature may assist or hinder cooling may depend on the efficiency of the system and the density of the racks.
  • Where will the airflow be directed? Directing the cooler airflow to the front of the racks is desirable, but how will the heated air be discharged? Standard airflow management in a small data center provides different design challenges.
  • Do load fluctuations exist and what impact do these have on the cooling response times? If the operation of the data center will see variations in energy use, a selected cooling system should be adaptable to the variations in power needs.
  • Should the system be scalable for future expansion? Having a system that can adapt to baying or can support additional rack cooling over the existing needs will eliminate costs if additional computing power is needed.

Cooling the edge computing microcenter can be approached most effectively via a liquid cooling system, either inline-based, rack-based, or a combination of both. There are two heat transfer media (water and refrigerant) that can work with these systems. Water offers exceptional cooling properties, well-suited to the high heat output of an edge system. Refrigerant-based cooling is well-suited to small or medium edge enclosures, especially when a water supply is not readily available. Refrigerant cooling often operates with a smaller footprint, efficient in microcenters. In both cases, energy efficiency is a consideration.

The energy-efficient, IT climate control system considers:

  • Dimensioning of the cooling systems to match the actual power requirements
  • Separation of cooling for server racks and room air conditioning by partitioning of aisles
  • Use of energy-efficient components, such as electronically commutated (EC) fans that include power regulation of the cooling compressors
  • Keeping the cooling water and room temperatures as high as possible
  • Controlling all subsystems and continuous adaptation to the actual cooling power requirements.

Liquid cooling package for thermal management

As data centers concentrate high-power servers in smaller footprints, the challenge of cooling these systems is greater. The power density of these server racks has increased from 2-8 kW per enclosure to more than 100 kW.

Providing a liquid cooling package (LCP) for an enclosure (suite-based or rack-based) can efficiently dissipate heat from IT racks. Applications may include aisle containment or closed-loop cooling of single- or dual-IT-rack enclosures.

LCPs are a reliable, cost-effective cooling means to provide cooling capacity of 3kW, up to as high as 60kW. LCP devices support IT-compatible cooling and can achieving up to 50% energy savings using intelligent control, free cooling, and additional fans that keep a steady volumetric flow and a constant cooling output.

In IT data centers confined in small spaces, such as edge computing, heat build-up is rapid, and an LCP matched to the enclosure can provide efficient closed-loop cooling. With high-performance EC fan technology, refrigerant cooled air is targeted to the racks. Servers are cooled independently from the ambient air, easily adapted to one enclosure or a modular series.

Certain LCPs are designed for a bayed enclosure suite. Hot air from the room or hot aisle at the rear of the device is efficiently chilled by the high-capacity variable speed compressor and the refrigerated air is directed back into the room or cold aisle after cooling.

Other attributes of an LCP may include air path control, small footprint, a design that augments fan life, redundant fan design, and efficient cool-air flows.

Protecting equipment with thermal management

Moving toward edge computing makes sense in many industries. With the rapidly increasing volume of data available from the Internet of Things (IoT), to the necessity of reduced latency in analysis, and the finite amount of bandwidth available at legacy data centers, edge computing solves these concerns. Understanding what an edge computing environment will require is not dissimilar to the checklist for any data center: calculate heat output, provide adequate cooling, assure reliability and scalability.

With edge computing, the smaller footprint of the microcenter demands a closer look at the proportions of the equipment relative to the size of the center, and strict parameters on the capacity of each component to perform efficiently and reliably.

When outside air can be used in dissipation of heat transfer, the proportion of indirect free cooling over the course of a year can be increased. This serves to reduce energy consumption, improve efficiency, and is environmentally-friendly.

With the ever-increasing densities and demands for more capacity, the protection of vital IT data from edge applications to large legacy data centers requires the reliability and selection of thermal management products. Energy efficient design lowers operating costs, while IT components work at capacity.

Hans Baumann is a product manager at Rittal Corp. Edited by Emily Guenther, associate content manager, Control Engineering, CFE Media,


Key Concepts

  • Requirements to consider for edge computing
  • Defining edge computing and its benefits
  • How to protect equipment with proper thermal management.

Consider this

What benefits would more efficient enclosure cooling offer beyond energy savings?

ONLINE extra

The New Products for Engineers Database has more information about the Rittal Liquid Cooling Package LCP Rack DX.

Author Bio: Hans Baumann is IT product manager, Rittal North America.