Many Data Centres tend to use closed-circuit air conditioning units, also known as CW units. CW units consist of an air/water heat exchanger, fans, air filters, control valves, the necessary electrical components and a controller. The cooled water supply to these units is provided by a centralised chiller. (Stulz, n.d).

Liquid cooling systems with centralised chilled water supply and CW precision air conditioning units are the most popular choice for large data centres. This is due to their good scalability and simple hydraulics. (Stulz, n.d).

Due to the rise of online and e-commerce activity, there has been an increase in demand for data centres. Factors such as COVID, have only further increased this; the rise of online shopping as well as the decline in high street brick and mortar shops, have been driven by the pandemic.

Other factors, leading to an increase in the demand for data centres include the rise of global internet traffic, including streaming, online gaming and video conferencing. (IEA, 2021). Additionally, the rise in emerging digital technologies such as blockchain and cryptocurrency, machine learning and virtual reality, also increase demand for data centres. (IEA, 2021).

Because of their strong prominence within society, it is very important that these data centres do not overheat and can therefore be cooled down effectively. However, these large data centres typically have lower power usage effectiveness; a measure of how efficiently a data centre uses energy, meaning that it uses a lot of energy to keep them cool (IEA, 2021). PICVs can be utilised in these large data centres to help increase efficiency, ensuring the data centres become more energy efficient.

A CW air conditioning unit tends to be made up of chilled water heat exchange and fans, as well as the chilled water control valve. In the past, either 3 or 2-way control valves were used, however presently, the Pressure Independent Control Valve is becoming more popular, being used to replace traditional 2-way control valves or ball valves. (Stulz, n.d).

The introduction of a new system design with Differential Pressure Control Valves, flow measurement and 2-Port control valves, allowed for the switch toward variable flow design strategies within the UK. In keeping with system development worldwide the UK finally adopted the PICV, simplifying selection, installation and control, as well decreasing the capital and running cost (FloControl, 2022).

The PICV valve is self-regulating, ensuring that the design flow rate is achieved at all times, in particular under partial load conditions. Therefore, this valve design lends itself perfectly to variable flow systems, present within large data centers (FloControl, 2022). ​

The Pressure Independent Control Valve can combine up to four valve functions within one valve unit: pressure independent control, measurement of the water flow, a shut-off function and automatic hydraulic balancing (Stulz, n.d).

Looking at PICVs, there are several main features that make a good PICV. Firstly, full valve stroke control capabilities at all settings with valve setting and control independency (FloControl, 2020). A PICV with full stroke at all settings is very important, no matter how high or low the flow is set, the valve should always allow for full stroke modulating control without any limitation of stroke. From a control aspect, it’s important to allow full stroke modulating control at all set points without sacrificing the stroke length (FloControl, 2022).

PICVs should also be easy to size and select and install. A benefit of PICVs is that they have 100% authority, meaning there is no need to calculate control valve authority (FloControl, 2022). Therefore, to size and select a PICV, only the flow rate and line size are required (FloControl, 2022). In terms of installation, the PIC Valve has no restrictions, and combined with the fact that one PICV replaces 3 valves- the DRV, 2-Port control valve and DPCV, this makes PICVs a perfect solution for installations with space restrictions (FloControl, 2022).

It is also important to select a PICV with the most accurate performance; a 1% increase in the accuracy of a PICV can result in the reduction of around 0.5% in the building’s overall HVAC energy consumption (FloControl, 2022). Good accuracy as well as high repeatability is also important. A PIC Valve with good repeatability and low hysteresis is important to achieve energy savings (FloControl, 2020).

PICVs should have some dirt tolerance and should be service-able. Rectangular openings work better than annular openings, allowing dirt particles to pass through more easily (FloControl, 2022). Additionally, a removable PICV insert allows the PICV to be cleaned without having to remove the actual valve housing from the system (FloControl, 2022). Other benefits of a removable insert include the option to supply a PICV with a blank cap so flushing through the PICV is completely avoided (FloControl, 2022). If flow rates also change significantly, due to a change in space usage, the PICV insert can be replaced with a higher or lower capacity insert, without needing to replace the whole valve.

Overall, a PICV can help lower costs, and increase efficiency, making it the perfect addition to CW units present within large data centres. Stable control is also guaranteed, regardless of load conditions (Stulz, n.d).

As the rise in demand for data centres increases, what does the future of these data centres look like? In 2020 it was reported that data centres accounted for 1% of global electricity demand (IEA, 2021). Therefore, it is important that data transmission network technologies are also becoming more energy efficient.

We can see the global internet traffic has more than doubled between 2017 and 2020, and if current trends are sustained, can double again by 2023 (IEA, 2021). Additional traffic such as mobile device traffic has also tripled in growth, resulting in the nature of data transmission changing rapidly (IEA, 2021). Since mobile network transmissions has a higher energy usage, it is important that we recognise the implications this may have on the overall data transmission network. However, this can also be combatted with the rise in 4G and 5G networks, networks that are much more energy efficient than previous 3G and 2G networks (IEA, 2021). Therefore, despite the rising demand for mobile networks, overall energy emissions can still be reduced by switching to more energy efficient networks.

Strong growth in demand for data centre and network services is expected to continue into the future (IEA, 2021). With factors such as video streaming, gaming and mobile networking, there is likely to be an increase in demand for more energy efficient data centres (IEA, 2021). ICT companies tend to invest in renewable energy, not only to reduce their environmental impacts and energy costs, but also to improve their brand reputation and protect themselves from power price volatility (IEA, 2021). This, along with further company and government efforts could help maximise energy savings to the fullest potential, helping to reduce emissions (IEA, 2021). There has been an increasing trend in the adoption of renewable energy, especially from ICT companies and sectors, and more ambitious approaches to reducing carbon emissions can have great environmental benefits (IEA, 2021).

The impact of valves and engineering within data centres is not to be underestimated. We have seen how valves such as the PICV can help increase energy efficiency, allowing companies and commit to these carbon reduction goals. Data centres can become even more energy efficient. And while demand for data centres will continuously grow, investing in Research and Development is of utmost importance, to allow for more energy efficient next generation of computing and communication technologies (IEA, 2021) and upkeep of infrastructure.

Stay tuned, we will cover next how energy valves can help reduce energy consumption in data centres.

References:

• • FloControl (2020), Why Should you use a Pressure Independent Control Valve?, FloControl https://www.flocontrol.ltd.uk/why-should-you-use-a-pressure-independent-control-valve/

  • FloControl (2022), Variable Flow Systems- Design & Operation of Pressure Control Valves, FloControl https://www.flocontrol.ltd.uk/continuous-professional-development/

  • IEA (2021), Data Centres and Data Transmission Networks, IEA, Paris https://www.iea.org/reports/data-centres-and-data-transmission-networks

  • Stulz (n.d.) Use of Pressure Independent Control Valves in CW Units, Stulz https://www.stulz.de/en/newsroom/blog/use-of-pressure-independent-control-valves-in-cw-units-1409/#:~:text=A%20control%20valve%20ensures%20that,full%20load%20or%20partial%20load).

  • Stulz (n.d.), Standby Management for CW Units, Stulz, https://www.stulz.de/en/newsroom/blog/standby-management-for-cw-units-77/