Most people take boiling water for granted. For Associate Professor Matteo Bucci, uncovering the physics behind boiling has been a ten-year journey filled with unexpected challenges and new insights.
This seemingly simple phenomenon is extremely difficult to study in complex systems such as nuclear reactors, but is at the heart of a wide range of important industrial processes. So unlocking its secrets could enable advances in efficient energy production, electronic cooling, desalination, medical diagnostics, and more.
“Boiling is important for applications other than nuclear,” said Bucci, who earned tenure at MIT last July. “Boiling is used in 80% of power plants that produce electricity. My research has implications for space propulsion, energy storage, electronics, and the increasingly important computer cooling tasks.”
Bucci’s lab has developed new experimental techniques to uncover a wide range of boiling and heat transfer phenomena that have limited energy projects for decades. The most important of these is the problem caused by bubbles forming too quickly, creating vapor bands across the surface and impeding further heat transfer. In 2023, Bucci and collaborators developed unifying principles for managing what became known as the boiling crisis. This can increase the efficiency of the reactor and prevent catastrophic failures.
For Bucci, each development brings new possibilities and new questions.
“What is the best paper?” Butch asks. “The best paper is the next paper. I think Alfred Hitchcock used to say that it doesn’t matter how good the last movie was. If the next person is poor, people won’t remember it. I always tell my students that the next paper should always be better than the previous one. It is a journey of continuous improvement.”
From engineering to bubbles
The Italian village where Butch grew up had a population of about 1,000 people during his childhood. He worked in his father’s machine shop and learned mechanical skills by disassembling and reassembling home appliances such as washing machines and air conditioners to see what they were like inside. He also developed a passion for cycling and participated in the sport until he attended the University of Pisa for his undergraduate and graduate studies.
In college, Bucci was fascinated by matter and the origins of life, but he also loved building buildings, so when it came time to choose between physics and engineering, he decided nuclear engineering was a good middle ground.
“I am passionate about construction and understanding how things are made,” says Bucci. “Nuclear engineering was a very unlikely but obvious choice. In Italy, this was highly unlikely as there were only a few of us there as nuclear power had already disappeared from the energy sector. “It was a combination of intellectual and practical challenges at the same time, which is what I like.”
To obtain his doctorate, Bucci traveled to France, where he met his wife and worked at the French National Research Institute. One day, his department head asked him to study a nuclear reactor safety problem known as transient boiling. To solve this, he wanted to use a measurement method pioneered by MIT professor Jacopo Buongiorno, and in 2013 he received a grant to become a visiting scientist at MIT. Since then, he has been studying boiling at MIT.
Currently, Bucci’s lab is developing new diagnostic techniques to study boiling and heat transfer, along with new materials and coatings that can make heat transfer more efficient. The study gave researchers an unprecedented view into conditions inside a nuclear reactor.
“The diagnostic method we developed can collect results equivalent to 20 years of experimental work in just one day,” says Bucci.
That data eventually led Bucci to a very simple model that explains the simmering crisis.
“The efficiency of the boiling process on the reactor cladding surface determines the efficiency and safety of the reactor,” explains Bucci. “It’s like a car where you want to accelerate but there’s an upper limit. “For nuclear reactors, that upper limit is determined by boiling heat transfer, so we are interested in understanding what that upper limit is and how we can overcome it to improve reactor performance.”
Another particularly influential area of research at Bucci is two-stage immersion cooling. This process involves hot server components boiling liquid, and then the resulting vapor condenses in a heat exchanger above, creating a continuous, passive cooling cycle.
“By keeping the chips cold while minimizing energy waste, we significantly reduce power consumption and carbon dioxide emissions in data centers,” explains Bucci. “Data centers emit as much CO2 as the entire aviation industry. By 2040, greenhouse gas emissions will account for more than 10% of total emissions.”
student support
Bucci says working with students is the most rewarding part of his job. “They have such great passion and ability. “It’s motivating to work with people who have the same passion as you.”
“My students are not afraid to explore new ideas,” adds Bucci. “They rarely stop in front of an obstacle. Sometimes you have to slow them down and get them back on track.”
In running the Red Lab in the Department of Nuclear Science and Engineering, Bucci strives to provide students with independence and support.
“We’re not educating students, we’re educating future researchers,” says Bucci. “I think the most important part of our work is not only providing the tools, but also the confidence and willingness to solve problems. It could be a business issue, an experimental issue, or an issue with a lab colleague.”
Bucci’s students performed some of the more unique experiments that required them to collect measurements while free-falling from an airplane to achieve weightlessness.
“Space research is every kid’s big fantasy,” says Bucci, who participates in experiments with students twice a year. “This is very fun and inspiring research for students. Zero g gives you a new perspective on life.”
AI application
Bucci is also excited about incorporating artificial intelligence into his field. In 2023, he was a co-recipient of a Multi-University Research Initiative in Thermal Sciences (MURI) project dedicated exclusively to machine learning. In a nod to the promise of AI in his field, Bucci recently launched the journal: AI thermal fluid Introducing AI-based research advancements.
“There is no space in our community for people who want to develop machine learning skills,” says Bucci. “We wanted to create a path for people in computer science and thermal science to work together and make progress. “I think we need to bring computer scientists into our community to speed up this process.”
Bucci also believes that AI can be used to process the enormous amounts of data collected using new experimental techniques he has developed and to model phenomena that researchers cannot yet study.
“AI can give us the opportunity to understand the unobservable, or at least guide us through the darkness as we try to find the root causes of many problems,” says Bucci.
