Evaluation of Phase Change Materials for Thermal Energy Storage in Immersion-Cooled Data Centers

Lucerne University of Applied Sciences and Arts

New Material for Data Center Heat Storage

As digitalization grows, data centers are booming, but so is their energy demand. Much of this energy goes into cooling the thousands of servers working around the clock. In a world trying to reduce CO₂ emissions, we need smarter ways to manage this heat. That’s where the MODERATOR project comes in with a solution that’s both clever and climate-friendly.

What’s the problem?

Data centers use a massive amount of electricity, and a large part of it is for keeping servers cool. Traditional air-cooling methods waste a lot of energy. At the same time, all that heat from servers could actually be reused, but only if we can store it effectively and safely.

What’s the solution?

The MODERATOR project explores an innovative combination: immersion cooling (where servers are dipped in cooling liquid) and thermal energy storage using Phase Change Materials (PCMs). These materials can store and release large amounts of heat when they melt and solidify, similar to how ice works in your drink, but at higher temperatures.

Our team at Lucerne University of Applied Sciences and Arts tested a specially developed PCM called PCM50, which melts around 50°C. That’s a sweet spot for capturing and reusing waste heat from data centers.

How was it tested?

We used a unique setup called the MiniCell, designed to simulate real conditions in thermal storage units. It allowed us to observe PCM50’s behavior during over 130 heating and cooling cycles. We also tested how the material interacts with metals like aluminum and copper to ensure it doesn’t cause corrosion in real systems.

What did we find?

• Stable storage: PCM50 performed reliably even after many heating and cooling cycles.
• Efficient heat release: It kept a constant temperature while releasing heat—a key advantage for systems that need steady thermal output.
• Good compatibility: The corrosion tests showed that common metals can be used safely, especially aluminum.

Why does it matter?

This research shows that smart heat storage is not just possible—it’s practical. PCM50 could be used in compact heat storage systems (like COWA Thermal Solutions’ CompactCell) to reuse server heat for heating buildings or water. That means less energy waste, lower CO₂ emissions, and reduced operating costs.

What’s next?

Our testing method using the MiniCell is already helping improve the way we evaluate PCMs. The next step is to build a more advanced test setup that mimics lab-grade instruments like a Differential Scanning Calorimeter, only with real-world volumes.

Why should you care?

If you run a data center, manage energy systems, or just care about smarter, greener technologies, this research shows that heat doesn't have to go to waste. With the right materials and systems, we can turn computational power into a heat resource.

Want to read the full paper? Conference proceedings will be published on https://climaworldcongress.org/