The boiling crisis — and how to avoid it

PhD student Madhumitha Ravichandran identifies the three main factors that trigger the boiling crisis through machine learning models.

Students, Graduate, postdoctoral, Nuclear science and engineering, Nuclear power and reactors, Profile, Energy, Thermodynamics, Heat, School of Engineering, Matteo Bucci, Bucci Lab, recently published paper

“I sometimes feel there was a reason I went through those early hardships,” says Madhumitha Ravichandran. “That’s what made me decide that I want to be an educator.” She’s also grateful for the opportunities that have opened up for her since coming to MIT. Photo: Gretchen Ertl

It’s rare for a pre-teen to become enamored with thermodynamics, but those consumed by such a passion may consider themselves lucky to end up at a place like MIT. Madhumitha Ravichandran certainly does. A PhD student in Nuclear Science and Engineering (NSE), Ravichandran first encountered the laws of thermodynamics as a middle school student in Chennai, India. “They made complete sense to me,” she says. “While looking at the refrigerator at home, I wondered if I might someday build energy systems that utilized these same principles. That’s how it started, and I’ve sustained that interest ever since.”

She’s now drawing on her knowledge of thermodynamics in research carried out in the laboratory of NSE Assistant Professor Matteo Bucci, her doctoral supervisor. Ravichandran and Bucci are gaining key insights into the “boiling crisis” — a problem that has long saddled the energy industry.

Ravichandran was well prepared for this work by the time she arrived at MIT in 2017. As an undergraduate at India’s Sastra University, she pursued research on “two-phase flows,” examining the transitions water undergoes between its liquid and gaseous forms. She continued to study droplet evaporation and related phenomena during an internship in early 2017 in the Bucci Lab. That was an eye-opening experience, Ravichandran explains. “Back at my university in India, only 2 to 3 percent of the mechanical engineering students were women, and there were no women on the faculty. It was the first time I had faced social inequities because of my gender, and I went through some struggles, to say the least.”

MIT offered a welcome contrast. “The amount of freedom I was given made me extremely happy,” she says. “I was always encouraged to explore my ideas, and I always felt included.” She was doubly happy because, midway through the internship, she learned that she’d been accepted to MIT’s graduate program.

As a PhD student, her research has followed a similar path. She continues to study boiling and heat transfer, but Bucci gave this work some added urgency. They’re now investigating the aforementioned boiling crisis, which affects nuclear reactors and other kinds of power plants that rely on steam generation to drive turbines. In a light water nuclear reactor, water is heated by fuel rods in which nuclear fission has occurred. Heat removal is most efficient when the water circulating past the rods boils. However, if too many bubbles form on the surface, enveloping the fuel rods in a layer of vapor, heat transfer is greatly reduced. That’s not only diminishes power generation, it can also be dangerous because the fuel rods must be continuously cooled to avoid a dreaded meltdown accident.

Nuclear plants operate at low power ratings to provide an ample safety margin and thereby prevent such a scenario from occurring. Ravichandran believes these standards may be overly cautious, owing to the fact that people aren’t yet sure of the conditions that bring about the boiling crisis. This hurts the economic viability of nuclear power, she says, at a time when we desperately need carbon-free power sources. But Ravichandran and other researchers in the Bucci Lab are starting to fill some major gaps in our understanding.

They initially ran experiments to determine how quickly bubbles form when water hits a hot surface, how big the bubbles get, how long they grow, and how the surface temperature changes. “A typical experiment lasted two minutes, but it took more than three weeks to pick out every bubble that formed and track its growth and evolution,” Ravichandran explains.

To streamline this process, she and Bucci are implementing a machine learning approach, based on neural network technology. Neural networks are good at recognizing patterns, including those associated with bubble nucleation. “These networks are data hungry,” Ravichandran says. “The more data they’re fed, the better they perform.” The networks were trained on experimental results pertaining to bubble formation on different surfaces; the networks were then tested on surfaces for which the NSE researchers had no data and didn’t know what to expect.

After gaining experimental validation of the output from the machine learning models, the team is now trying to get these models to make reliable predictions as to when the bubble crisis, itself, will occur. The ultimate goal is to have a fully autonomous system that can not only predict the boiling crisis, but also show why it happens and automatically shut down experiments before things go too far and lab equipment starts melting.

In the meantime, Ravichandran and Bucci have made some important theoretical advances, which they report on in a recently published paper for Applied Physics Letters. There had been a debate in the nuclear engineering community as to whether the boiling crisis is caused by bubbles covering the fuel rod surface or due to bubbles growing on top of each other, extending outward from the surface. Ravichandran and Bucci determined that it is a surface-level phenomenon. In addition, they’ve identified the three main factors that trigger the boiling crisis. First, there’s the number of bubbles that form over a given surface area and, second, the average bubble size. The third factor is the product of the bubble frequency (the number of bubbles forming within a second at a given site) and the time it takes for a bubble to reach its full size.

Ravichandran is happy to have shed some new light on this issue but acknowledges that there’s still much work to be done. Although her research agenda is ambitious and nearly all consuming, she never forgets where she came from and the sense of isolation she felt while studying engineering as an undergraduate. She has, on her own initiative, been mentoring female engineering students in India, providing both research guidance and career advice.

“I sometimes feel there was a reason I went through those early hardships,” Ravichandran says. “That’s what made me decide that I want to be an educator.” She’s also grateful for the opportunities that have opened up for her since coming to MIT. A recipient of a 2021-22 MathWorks Engineering Fellowship, she says, “now it feels like the only limits on me are those that I’ve placed on myself.”

Internet Explorer Channel Network
News Related

OTHER NEWS

Where Transcendental Numbers Hide in Everyday Math

The transcendental number π is as familiar as it is ubiquitous, but how does Euler’s number e transcend the ordinary? Read more »

Rishi Sunak accused of putting ‘prosecco before parents' as alcohol prices set to fall

Rishi Sunak delivers his budget to the House of Commons. (PA) Rishi Sunak has been accused of putting “prosecco before parents” amid criticism of plans to cut the price on ... Read more »

Our Yorkshire Farm couple address marriage speculation

Our Yorkshire Farm stars Amanda Owen and husband Clive have released a statement following reports speculating about their marriage. The couple, who have been married for 21 years and have ... Read more »

Alice Evans accuses estranged husband Ioan Gruffudd of having three-year affair

Actress Alice Evans has accused her estranged husband Ioan Gruffudd of having a three-year affair before they split up. Alice made the claims on Twitter after her 48-year-old ex posted ... Read more »

Third of new students in England show signs of depression, ONS survey suggests

Photograph: Guerilla/Alamy More than a third of <a href="/tag/first-year-students“>first-year students in England who started university this autumn have shown symptoms of depression and anxiety, a survey by the Office for ... Read more »

Florida judge sends Trump suit against Twitter to California

FILE – In this July 11, 2021, file photo former President Donald Trump speaks at the Conservative Political Action Conference (CPAC) in Dallas, Texas. Trump wants a federal judge in ... Read more »

Cops are collapsing after touching fentanyl, but you can't overdose from skin contact. The likelier story? Panic attacks.

San Diego County Sheriff’s Deputy David Faiivae gets aid from an officer after being exposed to fentanyl on July 3, 2021. Experts say it’s unlikely that Faiivae was overdosing. San ... Read more »

Serving Met Police officer Adam Zaman charged with rape

Pc Adam Zaman, 28, who is based on the East Area Command Unit, was charged by the City of London Police . A serving Metropolitan Police officer has been charged ... Read more »

12 best Bluetooth speakers for every budget: Portable, wireless and waterproof

We’ve tested mostly for audio excellence but also for ease of setup and snazziness of design (iStock/The Independent) What’s the best way to listen to music? We’re not talking about ... Read more »

EU court fines Poland €1m a day over judiciary row

EU court fines Poland 1 million euros per day over judiciary row – EPA-EFE/Shutterstock /Shutterstock The EU's top court on Wednesday ordered Poland to pay one million euros a day ... Read more »

Anthony Joshua Accepts Tyson Fury's Offer to Train Him – Under One Condition

Since his unanimous defeat against Oleksandr Usyk back in September we haven't heard too much from Anthony Joshua. Sure, there have been rumblings that he's been travelling around the US ... Read more »

SpaceX to fix leaky toilets ahead of planned launch at the weekend

The launch, from Cape Canaveral on Sunday, will mark SpaceX’s fourth launch of Nasa astronauts (REUTERS) SpaceX is having to fix its leaking toilets ahead of its planned launch at ... Read more »

Emmerdale star Danny Miller and fiancée Steph Jones welcome baby

Photo credit: @danny_b_miller – Instagram Danny Miller is now a dad after welcoming a baby with his fiancé. The Emmerdale actor announced that his partner Steph Jones had given birth ... Read more »

People who eat meat report lower levels of depression and anxiety than vegans do, a recent analysis suggests

A man eats his lunch at Holycow steak house in Jakarta, Indonesia on December 7, 2012. Reuters/Enny Nuraheni A recent analysis suggests a link between meat-free diets and poorer mental ... Read more »

Tech & Science Daily: The world's first ‘thinking' robot

(Yuichiro Yada, Shusaku Yasuda, and Hirokazu Takahashi) The world’s first ever ‘thinking’ robot has just been created. Using brain-like neurons grown in a lab, Japanese scientists managed to get the ... Read more »

Key budget announcements: Alcohol, fuel and tax changes revealed in chancellor's statement

Here are the key points from Chancellor Rishi Sunak's budget speech: • The chancellor says there are “challenging” months ahead, adding that inflation in September was 3.1% and is likely ... Read more »

At McKinsey, Widespread Furor Over Work With Planet's Biggest Polluters

A firefighter watches as a wildfire burns Wednesday, Oct. 13, 2021, in Goleta, Calif. A wildfire raging through Southern California coastal mountains threatened ranches and rural homes and kept a ... Read more »

Budget 2021: Sunak resets UK's spending focus for a post-covid economy

Watch: Rishi Sunak delivers his Budget speech after PMQs UK chancellor Rishi Sunak laid out sweeping plans for the next three financial years in his Autumn Budget and Spending Review ... Read more »

'Universe' and 'The Love Trap': The 5 best things on TV on Wednesday, 27 October

‘Universe’ and ‘The Love Trap’ are in Wednesday’s TV highlights. (BBC/ITV) Professor Brian Cox opens out eyes to the wonders of the solar system again tonight in new BBC Two ... Read more »

Great white shark bites a case of mistaken identity, study shows

Great white shark attacks are rare, and when they do occur, they are sometimes fatal. But attacks against the human species are often a result of mistaken identity, new research ... Read more »

SpaceX Needed to Fix the Toilet Before NASA Astronauts Launch

A image provided by NASA shows the SpaceX Crew Dragon capsule approaching the International Space Station for docking in April 2021. (NASA via The New York Times) NASA can’t call ... Read more »

Budget 2021: Rishi Sunak resets priorities as he unveils autumn spending review

Watch: Rishi Sunak delivers his Budget speech after PMQs UK chancellor Rishi Sunak laid out sweeping plans for the next three financial years in his Autumn Budget and Spending Review ... Read more »

Sally Nugent announced as Louise Minchin's replacement on 'BBC Breakfast'

Sally Nugent arriving for the BBC Sports Personality of the year 2019 at The P&J Live, Aberdeen. (Ian Rutherford/PA Images via Getty Images) BBC Breakfast has announced Sally Nugent as ... Read more »

Brutal crash as spectator runs into cyclist at El Hierro cycle race

A cyclist was involved in a brutal crash with a spectator at the finish line of a race in the Canary Islands, which left both the rider and the woman ... Read more »

Alan Cumming says ‘Hollywood saved me' from feeling suicidal

Alan Cumming shared how low he felt on the day of his GoldenEye audition. (Getty Images) Alan Cumming has opened up on feeling suicidal the day that he auditioned for ... Read more »

Wetherspoons to slash prices on certain drinks in November

Wetherspoons pubs across the UK are set to slash prices in November. Photo: Oli Scarff/AFP via Getty Wetherspoons (JDW.L) has said its pubs are set to lower prices on a ... Read more »

Trailer released for The Railway Children Return

The first trailer for The Railway Children Return has been released ahead of the sequel to the much-loved 1970 family film, which is due to hit cinemas in 2022. Read more »

Protesters from Insulate Britain covered in ink as they block A40

Insulate Britain has blocked part of the A40 in West London after declaring the M25 a site of nonviolent civil resistance yesterday. Members of the protest group are covered in ... Read more »

The youth movement grows up. Climate Fight podcast part four transcript

What effect does youth climate activism have on negotiations such as COP26 in Glasgow? John Gomez via Shutterstock This is a transcript of The youth movement grows up, part four ... Read more »

Scientists find harmful hormone-disrupting chemicals in US fast foods

(AFP via Getty Images) Hormone-disrupting chemicals, associated with adverse health outcomes, are abundant in meals available at popular American fast food restaurants, says a new study that calls for regulatory ... Read more »

Harvey Weinstein used Good Will Hunting to mess with Robin Williams' career, new book claims

Harvey Weinstein pulled a Robin Williams film from cinemas so that the actor wouldn’t make as much money, it’s been claimed. Writer, director and actor Kevin Smith claims in his ... Read more »

This Dream Vacation Hotspot Is Spiraling Into a Deadly Cartel Battlefield

DANIEL SLIM/AFP via Getty Images Two foreign female tourists were caught in a crossfire between rival crime groups and shot to death last Thursday in the high-end resort town of ... Read more »

Covid: Ministers put off decisions on restrictions and mandatory masks for two weeks

Covid: Ministers put off decisions on restrictions and mandatory masks for two weeks Ministers will not make a decision on Covid-19 restrictions for two weeks until the impact of half-term ... Read more »

Strictly's' Kai Widdrington addresses AJ Odudu romance rumours

Watch: Strictly's Kai Widdrington addresses AJ Odudu romance rumours Strictly Come Dancing star Kai Widdrington has spoken out about romance rumours with AJ Odudu, admitting they wanted people to think ... Read more »

Trump got de-platformed. Could the ‘decentralized crypto cloud' save him?

The blank check company that announced a planned merger to take former President Trump's social media project public has seen shares give back about half of their impressive 1200% rally ... Read more »

COVID: increased restrictions in the UK look inevitable as winter arrives

I Wei Huang/Shutterstock COVID-19 cases, hospitalisations and deaths have been rising in the UK, pressurising a health service that’s already working hard to treat the backlog of non-COVID patients that ... Read more »

Where does the youth climate movement go next? Climate Fight podcast part 4

MikeDotta/Shutterstock Locked out of conferences and company boardrooms, young people have tried to influence the international response to the climate crisis with strikes and protests. What effect does this youth ... Read more »

SpaceX aims to fix leaky toilets before astronauts blast off at weekend

SpaceX is facing toilet troubles in its capsules before it launches more astronauts into space. Related: SpaceX could make Elon Musk world’s first trillionaire, says Morgan Stanley The company and ... Read more »

‘Total dereliction of duty': 9 COVID hotspots emerge in areas hit by testing scandal

The Immensa Health Clinic which has been suspended from testing COVID-19 PCR swabs. (Getty Images) Public health experts have criticised the government's handling of the Immensa testing scandal amid spiking ... Read more »

Shirley Ballas receives 'concerning' test results

Shirley Ballas requires more tests after she received some “concerning” results, after 'Strictly Come Dancing' viewers spotted a lump under her arm. The 61-year-old head judge of the Latin and ... Read more »
On free-english-test.com you will find lots of free English exam practice materials to help you improve your English skills: grammar, listening, reading, writing, ielts, toeic