Performance improvement of high-density data center via two-phase liquid immersion cooling
Journal of Thermal Analysis and Calorimetry (Springer Science and Business Media LLC) · Nada M. Mohammed, Wael M. El-Maghlany et al.
Alexandria University researchers use 3D ANSYS CFD to compare cooling for a high-density data hall of up to 1168 kW: raised-floor air cooling with hot-aisle containment versus two-phase immersion tanks using FC-72, with copper coatings of different thicknesses tested on server components in the immersion case.
CC BY 4.0 — share with attribution
On this page
Overview
The study introduces two approaches for efficiently cooling high-density data centres with a capacity of up to 1168 kW, aiming to find the optimal method for extracting heat from electronic servers: air-based cooling with modifications to hot-aisle containment, and liquid-based cooling using a two-phase immersion system. Three-dimensional CFD simulations were conducted, and the influence of copper coating on server components in liquid cooling was examined by varying thickness.
With the best air configuration (raised floor plus hot-aisle containment), low-power racks ran at 50-90 °C and higher-power racks at 65-122 °C, with prominent hot spots from non-uniform airflow. Two-phase immersion with FC-72 kept low-power server tanks at 56 °C to below 61 °C and high-power servers at 56-65 °C at maximum hot spots. Total power for all high-power tanks was about 8.5 kW and for low-power tanks 7.5 kW, giving a reported liquid-cooling PUE of about 1.01 versus 2 for air cooling.
Copper coating lowered maximum temperature by 3 °C for high-power and 1.5 °C for low-power servers, with maximum uniformity improvements of 13% and 8% respectively. It gave a 13% improvement in temperature distribution among high-power servers and eliminated most hot spots by decreasing the maximum temperature, against 8% for low-power servers.
Limits: the reported PUE of 1.01 counts only tank-level power and excludes the external heat-rejection loop (heat exchangers, pumps, pipes), which the authors leave for future work, so it is optimistic. The study is CFD only, with no experimental validation.
Key points
- The study considers high-density data centres with a capacity of up to 1168 kW.
- With the best air configuration (raised floor plus hot-aisle containment), low-power racks ran at 50-90 °C and higher-power racks at 65-122 °C, with prominent hot spots from non-uniform airflow.
- Two-phase immersion with FC-72 kept low-power server tanks at 56 °C to below 61 °C and high-power servers at 56-65 °C at maximum hot spots.
- Total power for all high-power tanks was about 8.5 kW and for low-power tanks 7.5 kW, giving a reported liquid-cooling PUE of about 1.01 versus 2 for air cooling.
- Copper coating lowered maximum temperature by 3 °C for high-power and 1.5 °C for low-power servers, with maximum uniformity improvements of 13% and 8%.
- Future work is stated to include the full liquid-cooling cycle (heat exchangers, pumps, pipes), so the system efficiency figures exclude that loop.
Using it in design
- Verify two-phase immersion PUE claims so they include the external heat-rejection loop (exchangers, pumps, pipes) and not just tank-level power; the 1.01 figure excludes it.
- Compare the air-cooling hot-spot risk in a high-density hall (65-122 °C) with the uniform temperature of two-phase immersion (56-65 °C).
- Consider copper coating as a hot-spot reduction option for high-power servers (maximum temperature -3 °C, uniformity 13%).
Monthly newsletter · free
Keep your reading list current
Once a month: new library sources, changes to Turkish regulations and upcoming data centre events.
SoSo CAD
Check cooling capacity alongside your design
Review zone heat loads, available capacity and the capacity balance after the largest unit is lost in SoSo CAD.
Request a demo
Who should read it
Cooling designers comparing air and two-phase immersion cooling for high-density halls.
Document contents
- Introduction
- Methodology (air-based cooling configurations, two-phase immersion tanks, CFD model)
- Results (air-cooling temperatures, two-phase immersion temperatures, copper coating effect, PUE)
- Conclusion and future work
Read the document
two-phase-immersion-hd-dc-performance-2025.pdf
CC BY 4.0 — share with attribution
The document is provided unaltered because its licence permits redistribution.
Publication details
- Authors
- Nada M. Mohammed; Wael M. El-Maghlany; Mohamed Elhelw; Ahmed H. Abdelaziz
- Publisher
- Journal of Thermal Analysis and Calorimetry (Springer Science and Business Media LLC)
- Year
- 2025
- Volume
- 150
- Issue
- 6
- Pages
- 4279-4294
- Document language
- English
- Source type
- Scientific
- Access
- Open licence — downloadable
- Licence
- CC BY 4.0 — share with attribution
- Licence evidence
- doi.org
Original licence note
Article states it is open access under a Creative Commons Attribution (CC BY / CC BY 4.0) licence (verified in PDF text).
Citation
Nada M. Mohammed; Wael M. El-Maghlany; Mohamed Elhelw; Ahmed H. Abdelaziz (2025). Performance improvement of high-density data center via two-phase liquid immersion cooling. Journal of Thermal Analysis and Calorimetry (Springer Science and Business Media LLC). 150(6), 4279-4294. https://doi.org/10.1007/s10973-025-14006-0
Events on this subject
- SC26 – International Conference for High Performance Computing, Networking, Storage and Analysis
- Data Center World Middle East
- Datacenter Forum Stockholm
All content and rights belong to the respective authors and publishers. SoSo CAD provides only the citation, its own summary and a link to the source, and is not responsible for the sources' content.
Related sources
All sources on this topicASHRAE TC 9.9 2021
Emergence and Expansion of Liquid Cooling in Mainstream Data Centers
Add class H1 and the W17/W27/W32/W40/W45/W+ facility-water classes to the thermal catalog as enumerations.
- Context: A1 allowable max 32 degC, A4 max 45 degC.
Buildings (MDPI AG) 2026
Thermal Environment Assessment for Energy-Efficient Cooling in Air-Cooled Data Centers: Measurement, CFD, and Predictive Models
In a design tool, set CFD accuracy expectations from this review's ranges (0.1-4 °C absolute, relative mostly below 20%) and do not limit validation scope to temperature; ask for velocity and pressure too.
- Of the 58 CFD studies, Fluent was used in 24 (41.4%) and 6SigmaDC in 12; standard k-epsilon in 41 (about 70.7%).
Fluids (MDPI AG) 2026
A Review of Thermal Management in Modern Data Centres: Water Usage Effectiveness and Heat Transfer Coefficients
Set WUE targets from the heat-rejection topology (dry, free-cooling, hybrid, evaporative) and not only the server-side cooling technology; WUE depends on the share of heat rejected by evaporation.
- Dry facilities with closed-loop liquid cooling need essentially no water, while evaporative systems typically report WUE up to 2.5 L/kWh.
Open Compute Project Foundation 2026
Open Data Center: Next-Generation ML Infrastructure Design Principles, Revision 0.7.0 (Design Specification, effective Aug 27, 2026)
Base floor and transport-route load checks on the 8,000 lb rack and the 15,000 lb rack-plus-sidecar combination, and include the weight of the moving equipment.
- Available quick connects currently top out at 2 in.
Applied Sciences (MDPI AG) 2025
Optimization of Airflow Organization in Bidirectional Air Supply Data Centers in China
In retrofitting an existing raised-floor hall, first close unused rack spaces with blanking panels (alone they cut SHI by 42.61%); containment alone gave little benefit.
- Baseline RTI 0.786, SHI 0.230, RCI-HI 0.992. Blanking alone: SHI 0.132, RCI-HI 1. Blanking plus full CAC (Case 7): RTI 1, SHI 0.027.
Scientific Reports (Springer Science and Business Media LLC) 2025
Energy efficiency enhancement in two European data centers through CFD modeling
Set up the retrofit workflow as KPI-guided: with a validated CFD model compute RCI, RHI, RTI and the recirculation index, then test rack repositioning, separators, sealing unused bays and removing badly placed ventilation units in sequence.
- KPI limits: ASHRAE recommended 18-27 °C and allowable 15-32 °C inlet temperatures.