Rack Computer Cooling Methods

Jake MacWhirter
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The airflow of a rack-mounted computer cabinet is critical.

Consider for example all of the components within an enclosed rack – if heat is transferred from one component to another, it can act as a chamber of increasing temperature making the computers themselves vulnerable to failure.

Therefore, a rack-mounted computer cabinet, if not designed or engineered sufficiently, can add unnecessary thermal-stress on the computers and all other components, and ultimately lead to application failure and downtime.

In this blog, we have detailed some methods to ensure your rack computers stay cool, and operational.

 

Flow Patterns and Obstructions

Rack computer cabinets come in many styles and in terms of airflow, can be configured in many ways.

It’s important to understand the airflow available on site, whether it is a hot and cold aisle, open floor tiles, room neutral or a large air-conditioned room.

In addition, account for the contribution the equipment will have to the ambient cooling solution (additional load), and if there is sufficient overhead to support this.

Once an understanding of this has been established, decide how best to manage the air flow through the cabinet.

For example, consider if the cabinet will have glass or steel doors, high flow vented doors or no doors at all.

 

Getting Air Through the Cabinet

Unfortunately, not all 19″ rack cabinet equipment is designed with a common airflow in mind. Typically, it falls into three separate camps, front-to-rear, side-to-side, and fanless.

However, rear-to-side, side-to-rear, and even front-to-side and virtually any other combination can be seen.

This represents the first obstacle to managing airflow within the cabinet: ensuring the equipment has a clean supply of air as close to the ambient temperature as possible.

 

Review Component Selection

In order to achieve optimal airflow, it is important to review component selection to ensure an understanding is established of the airflow requirements for each item.

Where possible, items with similar flow patterns should be grouped together, and where flow is a concern, additional space should be attributed above and below the unit.

There is typically void space in the sides of cabinets, but this can quickly become obstructed with cabling and support rails.

Particular attention should also be given to 1U devices – telescopic or fixed slide rails will often attenuate airflow.

Consider a wider cabinet where appropriate or for mission-critical applications.

 

Depth of Equipment and Vertical Issues

There is often a demand to keep the footprint of a rack as small as possible.

Although this may present a saving floor area usage, this is typically a tradeoff that limits the equipment that can be installed and reduces overall stability.

For example, cabinets of up to 56U and a footprint of 600 by 800 will have a different centre of gravity to an 800 by 1200 38U.

The additional height may be difficult to manage and can cause complications in terms of installation or servicing.

There is also a heightened opportunity for airflow to be attenuated, hotspots to be created or recirculation to occur as cabinets become taller.

Smaller cabinets are being continuously pushed. Unfortunately, for the data and computing industry this is conflicted by the development of standard 19″ computing platforms and data storage systems. These have reduced in U height over the years, while increasing in depth.

In real terms, this means that the attenuation of airflow in the vertical stack must be considered during the design phase for the life of the cabinet.

Remember to allow for cable bend radius and cable management arms in the overall depth calculations, as manufacturers do not typically include this in system depth information.

If your configuration is likely to develop choke points behind some of the longer items, review the potential for a deeper cabinet or perforated rear door. This can reduce issues significantly.

 

Summary

There are a number of considerations to be made when designing a rack cabinet for your rackmount computers and associated components. A careful review of the complete unit, its installed parts and the air flow is critical and will make a very big difference in the overall life expectancy of the products within the cabinet.

To learn more or get project support from Captec visit our rackmount computer web page.

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