Spotlight on Research: Dr Sajad Alimohammadi

Author - Dr Sajad Alimohammadi (left), Prof Tim Persoons (right)

Posted: 23 July, 2021

How we manage the energy demands of data centres is vital to ensuring a greener future for Ireland and internationally. Former Irish Research Council awardee Dr Sajad Alimohammadi, Lecturer in Mechanical Engineering at Technological University Dublin, is leading research on how to make data centres more sustainable. He recently received the prestigious Harvey Rosten Award 2020 for Excellence in the Physical Design of Electronics with Professor Tim Persoons at Trinity College Dublin.

Tell us about the research you’re currently working on

It is estimated that over a quarter of the electricity produced in Ireland will be needed to power data centres by 2027. Over the past year alone, the number of operational data centres in Ireland has increased by 25%. I am leading a research group at the School of Mechanical and Design Engineering, TU Dublin, in collaboration with Professor Tim Persoons at the Department of Mechanical, Manufacturing and Biomedical Engineering, TCD, exploring the wide spectrum of data centre thermal management, with the aim of developing technologies to make these systems more efficient. My ultimate goal is to enhance the cooling and energy infrastructure required by data centres in order to decarbonise the electricity demand for Ireland and around the world, working towards a greener future.

My research focuses on applied thermal-fluid sciences and novel energy efficiency technologies using a mix of laboratory experiments and computer-based simulations.  Like most compact high-performance electronics, servers in data centres still heavily depend on air-cooling systems to maintain the continuous operation of the server racks. The operation of the fans, however, provide challenges to data centre thermal management such as low cooling efficiency, high noise levels, and operational and maintenance costs. This is why hybrid (combined air and liquid) cooling technologies are developing fast. This hybrid approach benefits from the higher heat dissipation capacity of water, along with the added ability to capture and reuse the waste heat generated by the data centre.


Computer visualisation of flow fluid using Computational Fluid Dynamics in a data centre server air cooling system using Air Amplifier

What inspired you to pursue research in this area?

I am a former PhD student and postdoctoral research fellow in Prof Persoons’ research group at TCD. The main spark of interest came during, and immediately after, my PhD graduation when I started my postdoctoral fellowship with Prof Persoons (who was also my PhD co-supervisor) at the Fluids and Heat Transfer laboratory on a project in collaboration with the Cooling Technologies Research Center (CTRC), Purdue University, USA. He first drew my attention to this research area and had a famous saying about ‘not letting great ideas rest in our drawers’. This continues to inspire my current research interests and has been a key principle in my present role as Lecturer in Mechanical Engineering at TU Dublin.

In your opinion, why is your research important?

The major recent investment by several multinational information technology (IT) companies in data centres in Ireland has resulted in 15% of Irish electricity being consumed by data centres in 2020, a figure that has the potential to rise above 30% in the coming years. Up to one-third of this energy is used to cool down the servers. The cooling technologies utilised in Irish data centres will require reformative action in order to meet European Green Deal goals. Waste heat recovery and alternative/novel cooling methods are all options to facilitate the transition to a sustainable and low carbon energy future while maintaining the capacity of the Information and Communications Technology (ICT) sector as one of the main drivers of the Irish economy.

What are some of the greatest challenges facing researchers in your field? What are the greatest opportunities?

The Covid-19 pandemic has intensified the argument for robust ICT infrastructures. It is imperative to develop sustainable energy-efficient data centres and to help strengthen the foundation of Ireland’s economy. The current operation of data centres in Ireland presents a dilemma for the country given their excessive energy demands and carbon emissions vs the many advantages they offer. However, between 15% to 40% of the energy consumption in such facilities is required for cooling the electronics, and this poses a huge opportunity for savings, one which will require strategic research actions in this area.


Computer simulation of acoustic noise propagation using Computational Aero-Acoustics in a data centre server air cooling system using Air Amplifier

Computer simulation of acoustic noise propagation using Computational Aero-Acoustics in a data centre server air cooling system using Air Amplifier

How has the Irish Research Council supported you in your work?

The Government of Ireland Postdoctoral Fellowship is one of the most competitive and prestigious schemes in Europe and gives the awardee a great track record for exceptional performance up to that stage of their career. What else could one ask for but to be driven enough and thrive! I see this award as a jumpstart for someone who is competitive at this particular stage of his/her post PhD career and simply needs one last push to make it happen and advance their research. This award kicked in at a crucial time when we had developed an idea and completed the necessary tailoring and feasibility studies, but could not progress until obtaining further support and funding.


Experimental visualisation of fluid flow using Particle Image Velocimetry in a data centre server air cooling system using Air Amplifier

You recently won a major award for your research, can you tell us more about this?

I was awarded the Harvey Rosten Award for Excellence in the Physical Design of Electronics alongside Prof Persoons in 2020. The award is presented annually in recognition of achievements in the field of thermal analysis of electronics equipment, and the thermal modelling of electronics parts and packages. Our winning project focused on the development and evaluation of a linear air amplifier that could offer a more reliable alternative to rotary fans for cooling data centre servers. The project was accomplished with the assistance of Mr Gordon O’Brien and Dr Quentin Pelletier in TCD. It was initially funded by the CTRC at Purdue University and Intel Corporation, from 2015 to 2016, followed by IRC Government of Ireland funding until 2018. I have admired some of the former awardees as role models since the start of my research in this field and this makes it a very special achievement of my career.

Dr Sajad Alimohammadi is a former IRC Government of Ireland Postdoctoral Fellowship awardee (2016-2018). He currently lectures in Mechanical Engineering at Technological University Dublin. Find Sajad on Twitter @SajadAMO.

The opinions expressed here are those of the author and do not represent or reflect the views of the Irish Research Council.

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