It’s a problem that has intrigued scientists for a century. But, backed by a $625,000 Distinguished Early Career Award the US Department of Energy (DoE), Matteo Bucciassociate professor in the Department of Nuclear Science and Engineering (SNG), hopes to be close to an answer.
Facing the boiling crisis
Whether you’re heating a pot of water for pasta or designing nuclear reactors, one phenomenon – boiling – is vital to the efficient execution of both processes.
“Boiling is a very efficient heat transfer mechanism; it’s the way to remove large amounts of heat from the surface, which is why it’s used in many high-power-density applications,” says Bucci. An example of a use case: nuclear reactors.
To the layman, boiling seems simple – bubbles form and burst, removing the heat. But what if so many bubbles form and coalesce that they form a band of vapor that prevents further heat transfer? Such a problem is a known entity and goes by the name of boiling crisis. This would lead to heat runaway and fuel rod failure in nuclear reactors. Thus, “understanding and determining under what conditions boiling crisis is likely to occur is essential for designing more efficient and competitive nuclear reactors,” says Bucci.
The earliest work on the boiling crisis dates back nearly a century, to 1926. And while a lot of work has been done, “it’s clear we haven’t found an answer,” Bucci says. The boiling crisis remains a challenge because while models abound, measuring related phenomena to prove or disprove these models has been difficult. “[Boiling] is a process that happens on a very, very small scale of length and over very, very short durations,” says Bucci. “We are not able to observe it at the level of detail necessary to understand what is really happening and validate the hypotheses.”
However, over the past few years, Bucci and his team have developed diagnostics capable of measuring boiling-related phenomena and thus providing essential answers to a classic problem. Diagnostics are grounded in infrared thermometry and a technique using visible light. “By combining these two techniques, I think we will be ready to answer the ongoing questions related to heat transfer, we can come out of the rabbit hole,” says Bucci. The US DoE Fellowship for Nuclear Power Projects will contribute to this and other Bucci research efforts.
An idyllic Italian childhood
Tackling tough problems is not new territory for Bucci, who grew up in the small town of Città di Castello near Florence, Italy. Bucci’s mother was an elementary school teacher. His father had a machine shop, which helped develop Bucci’s scientific bent. “I really liked LEGO when I was a child. It was a passion,” he adds.
Although Italy went through a severe setback in nuclear engineering during its formative years, the subject fascinated Bucci. Job opportunities in the field were uncertain, but Bucci decided to dig in. “If I have to do something for the rest of my life, it might as well be something I love,” he jokes. Bucci attended the University of Pisa for undergraduate and graduate studies in nuclear engineering.
His interest in heat transfer mechanisms took root during his doctoral studies, a research subject he pursued in Paris at the Commissariat for Alternative Energies and Atomic Energy (CEA). It was there that a colleague offered to work on the boiling water crisis. This time, Bucci set his sights on NSE at MIT and contacted Professor Jacopo Buongiorno to inquire about research at the institution. Bucci had to raise funds at the CEA to conduct research at MIT. He arrived just days before the Boston Marathon bombing in 2013 on a return ticket. But Bucci has stayed since, becoming a research scientist and then an associate professor at the NSE.
Bucci admits he had a hard time adjusting to the environment when he arrived at MIT, but work and friendships with colleagues – he counts NSE Guanyu Su and Reza Azizian among his best friends – helped overcome early worries.
The integration of artificial intelligence
In addition to boil diagnostics, Bucci and his team are working on ways to integrate artificial intelligence and experimental research. He is confident that “the integration of advanced diagnostics, machine learning, and advanced modeling tools will blossom in a decade.”
Bucci’s team is developing a self-contained laboratory for boiling heat transfer experiments. Running on machine learning, the setup decides which experiments to run based on a learning goal that the team assigns. “We formulate a question and the machine will respond by optimizing the kinds of experiments needed to answer those questions,” Bucci says, “I honestly think this is the next frontier for boiling,” he adds.
“It’s when you climb a tree and reach the top that you realize that the horizon is much wider and also more beautiful,” Bucci says of his zeal to pursue more research in the field. .
Although he seeks new heights, Bucci has not forgotten his origins. Commemorating the hosting of the World Cup in Italy in 1990, a series of posters depicting a football pitch set up in the Roman Colosseum take pride of place in his home and office. Created by Alberto Burrithe posters have sentimental value: the Italian artist (now deceased) was also from Bucci’s hometown of Città di Castello.