Tag Archives: Thermal

Challenging Thermal Radiation Limits May Lead to Improved Solar Cell Technology

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By manipulating fundamental physics, researchers can enhance energy-harvesting devices like solar cells

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Researchers have challenged long-standing principles of physics, paving the way for more efficient energy harvesting technologies, such as solar cells.

Linxiao Zhu from Penn State University has aimed to break Kirchov’s law of thermal radiation for nearly ten years. Established in the 1800s, this law states that the amount of thermal radiation emitted by an object is proportional to the heat it absorbs, linking to the fundamental principles of thermodynamics. Historically, it was believed that these constraints were absolute.

“In standard physics literature, it’s indicated that Kirchov’s law is a fundamental requirement of the second law of thermodynamics. However, this is not entirely accurate,” explains Zhu.

Previous breaches of this law were seen, but only concerning specific wavelengths of radiation. Zhu and his team have achieved a more significant departure from the norm.

This breakthrough required two significant elements: precisely structured materials and magnetic fields. Both the arrangement of the material and the magnetic environment play crucial roles in the behavior of the particles making up the radiation, like photons, and the energy they carry.

The researchers developed thin-layered semiconductors from indium, gallium, and arsenides, meticulously organizing the atoms. They positioned this setup near a strong electromagnet, illuminating it with lights of various colors at distinct temperatures, angles, and magnetic field strengths.

This combination of material structure and ongoing magnetic influence led to a significant disparity between the radiation absorbed and emitted—up to 43% more radiation was released than was originally absorbed. Zhu attributes this phenomenon to the presence of multiple colors of light. This characteristic is particularly beneficial since sunlight comprises a mixture of colors when hitting solar cell devices.

Aaswath Raman from UCLA indicates that this trial is a major advancement toward turning previously theoretical concepts into reality. He remarks that the stark difference between absorbed and emitted radiation is “a significant breakthrough.”

While novel materials can enhance the efficiency of light and heat-absorbing devices, the requirement for magnetic fields presents challenges. However, Raman remains optimistic about the emergence of new materials that display magnetic properties without requiring proximity to magnets, which could resolve these issues through innovative electromagnetic techniques.

Source: www.newscientist.com

The Importance of Thermal Storage in the Expansion of Renewable Energy

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Artur Widak/NurPhoto/Shutterstock

It's now well established that to mitigate the worst effects of climate change, we need to get to net zero carbon emissions as quickly as possible, which means getting more of our energy from renewable sources and finding ways to store energy for long periods of time to overcome the intermittency of wind and solar.

Giant battery farms and green hydrogen (using surplus renewable energy to split water) are often touted as the most promising storage solutions, and clever new ways to store excess electricity are emerging all the time (see “Giant CO2-filled domes could store surplus renewable power”), but the potential to store renewable energy as heat is often overlooked.

When we think of renewable energy, we tend to think of electricity. But heat is also a valuable commodity in its own right. About half of the world's total energy demand is for heat, whether it's to heat our homes or to power industrial production of food, medicines and materials. What's more, stored heat can be used to generate electricity when the sun stops shining and the wind dies down.

The good news is that, as we outlined in our feature “How Incredibly Simple Technologies Can Accelerate the Race to Net Zero”, a range of thermal storage technologies are emerging. Collectively known as thermal energy storage (TES), many of these innovations are incredibly simple, from baked bricks to molten salt. Crucially, they're affordable: early estimates suggest that these technologies could be as little as one-fifth the cost per kilowatt-hour of energy storage using green hydrogen. In a recent report, the International Renewable Energy Agency said TES offers “unique advantages”.

The problem is that awareness of TES is relatively low, and investment even less. Private backers are starting to pour big dollars into pilot projects in the US and Europe. But for TES to live up to its promise as a relatively easy way to make a big impact on the problem of renewable intermittency, governments will need to step up. And if the price is as reasonable as it appears, there's no reason not to.

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Source: www.newscientist.com

Miami Welcomes the World’s First Chief Thermal Officer

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MIAMI BEACH, Fla. — Jane Gilbert embraced the pleasant weather and light breeze of early March while hurrying between meetings. She is well aware that the heat is on its way.

At the Miami Beach Convention Center, Gilbert and numerous scientists, policymakers, activists, and business leaders have convened for the Aspen Ideas: Climate conference. This three-day event focuses on discussing solutions and adaptations to combat global warming.

Gilbert serves as the Chief Heat Officer for Miami-Dade County, a region with over 2.6 million residents situated at the southeastern end of Florida. In 2021, she made history by becoming the first person globally to hold such a position. Since then, others have followed suit in cities worldwide facing the challenges of extreme heat in a warming climate.

Chief heat officers from various locations communicate through a WhatsApp group, exchanging insights and advocating for policy modifications.

Speaking about her interactions, Gilbert stated, “I mostly collaborate with the chief heat officers in Phoenix and Los Angeles, but I’ve also gained knowledge from Melbourne, Australia, Santiago, Chile, and Athens, Greece. Sharing resources like this is one of the most rewarding aspects of my job.”

In South Florida, renowned for its tropical climate, Gilbert’s primary objective is safeguarding residents from intense heat and humidity while enhancing the county’s resilience against heatwaves exacerbated by climate change.

Those particularly at risk when temperatures soar include children, the elderly, the homeless population, individuals who work outside, and those in low-income communities.

Gilbert highlighted, “If you reside and work in an air-conditioned environment and have the means for an air-conditioned vehicle, you’re likely covered. Our main concern is for individuals working outdoors, those unable to stay cool at home, and those enduring long waits at unsafe bus stops.”

Her efforts in aiding the most vulnerable were crucial last year when Miami encountered its hottest summer to date.

She shared, “Over the last 14 years until 2023, the average number of days annually with a heat index surpassing 105 degrees was six. Last summer, it exceeded 42 days, a staggering seven times the norm.”

Numerous forecasts indicate that the situation could worsen. 2023 marked the hottest year on record globally. Climate experts project that this year might be equally scorching, if not more.

Recalling the skepticism she faced upon her appointment, Gilbert emphasized the urgency of having professionals dedicated solely to addressing heat-related challenges in South Florida.

“While it’s always warm here, there are now 77 additional days above 90 degrees compared to five decades ago,” she mentioned. “That’s a significant escalation.”

Heat is often dubbed a “silent killer,” causing more deaths annually in the United States than any other weather phenomenon, according to the National Weather Service. Gilbert noted a surge in heat-related ER visits last summer amidst the temperature spikes.

Studies suggest that by the middle of this century, this region of Florida may face heat index temperatures of 105 degrees Fahrenheit or higher for a duration of approximately 88 days each year, roughly three months.

Given the predictions, Gilbert stressed the urgency in taking action.

Ahead of the impending heat surge, her team is reaching out to renters and homeowners regarding cost-effective cooling methods. Training programs are also lined up for healthcare workers, homeless outreach workers, and summer camp providers, similar to last year.

She reiterated, “Our top priority is reaching the most vulnerable groups and tailoring messages for varied communities. That’s why we use English, Spanish, and Haitian Creole to communicate about the risks of extreme heat and preparation methods through radio, social media, and community platforms.”

Over the next month, the focus will shift to educating employers on safeguarding workers. This initiative became more pressing after the Florida Senate sanctioned a bill that would bar local governments from enforcing mandatory water breaks or workplace safety standards against extreme heat beyond federal regulations.

Gilbert expressed concern about the bill’s potential repercussions, citing statistics showing that construction workers are up to 11 times more susceptible to heat-related illnesses during extreme temperatures than the average person. Agricultural workers face an even higher risk, being 35 times more vulnerable.

Despite the challenges, Gilbert believes progress can still be achieved in advocating for employers to adhere to OSHA guidelines, enhancing productivity during hot spells, improving worker retention, reducing compensation claims, and yielding other economic benefits.

She emphasized, “This is where we must focus our efforts. By collaborating with OSHA offices, we can recognize the compliant entities and, in some cases, address non-compliance.”

Having served as the chief resilience officer for the City of Miami previously, Gilbert is well-versed in navigating legal obstacles. She acknowledged the irony of hosting this week’s climate conference in a city often referred to as the “epicenter” of the nation’s climate crisis.

“Florida is a complex landscape when it comes to politics, and I’m accustomed to climate change being a contentious topic,” she noted. “Nevertheless, I’ll do my part, right?”

Source: www.nbcnews.com

Revolutionary Solid-State Thermal Transistor Unveiled by UCLA

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UCLA researchers have unveiled a new solid-state thermal transistor that uses electric fields to effectively control the movement of heat in semiconductors. This represents a major advance in the thermal management of computer chips and potential applications in understanding the thermal regulation of the human body. An illustration of a UCLA-developed solid-state thermal transistor that uses electric fields to control heat transfer. Credit: H-Lab/UCLA

New electronic devices precisely and quickly control turning heat on and off.

A team of UCLA scientists has unveiled the first stable, fully solid-state thermal transistor of its kind that uses electric fields to control thermal movement in semiconductor devices.

Group research recently published in journals scienceLet’s take a closer look at how the device works and its potential uses. With the highest speed and performance, this transistor could break new ground in thermal management in computer chips through atomic-level design and molecular engineering. This advance could also improve our understanding of how the human body regulates heat.

A leap forward in thermal management technology

“Precise control over how heat flows through materials has long been a dream of physicists and engineers, but an elusive dream,” said co-author of the study, a professor of mechanical and aerospace engineering. Professor Yongji Hu said. DOI: 10.1126/science.abo4297

Other authors on the paper, all from UCLA, include Man Li, Huan Wu, Erin Avery, Zihao Qin, Dominic Goronzy, Huu Duy Nguyen, and Tianhan Liu. Hu and Weiss are also affiliated with the California NanoSystems Institute and UCLA Samueli’s Department of Bioengineering and Department of Materials Science and Engineering.

This research

Source: scitechdaily.com

Thermal secrets uncovered in neutron star mergers through gravitational waves

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by US Department of Energy
December 14, 2023

Scientists used supercomputer simulations to study gravitational waves produced by neutron star mergers and found a correlation between residual temperature and gravitational wave frequency. These findings are important for future gravitational wave detectors that distinguish models of hot nuclear material. Credit: SciTechDaily.com

Binary simulation neutron star This merger suggests that future detectors will distinguish between different models of hot nuclear material.

Researchers used supercomputer simulations to investigate the effects of neutron star mergers gravitational waves, found a significant relationship with debris temperature. This research will aid future advances in the detection and understanding of hot nuclear materials.

Exploring neutron star mergers and gravitational waves

When two neutron stars orbit each other, they emit ripples into spacetime called gravitational waves. These ripples drain energy from the orbit until the two stars eventually collide and combine into one object. Scientists used supercomputer simulations to investigate how the behavior of different models of nuclear material affects the gravitational waves released after these mergers. They found a strong correlation between the temperature of the debris and the frequency of these gravitational waves. Next generation detectors will be able to distinguish these models from each other.

Plot comparing density (right) and temperature (left) for two different simulations (top and bottom) of a neutron star merger, viewed from above, approximately 5 ms after the merger.Credit: Jacob Fields, Pennsylvania State University

Neutron Star: Institute for Nuclear Materials

Scientists use neutron stars as laboratories for nuclear materials under conditions that would be impossible to explore on Earth. They will use current gravitational wave detectors to observe neutron star mergers and learn how cold, ultra-dense matter behaves. However, these detectors cannot measure the signal after the stars have merged. This signal contains information about hot nuclear material. Future detectors will be even more sensitive to these signals. Because different models can also be distinguished from each other, the findings suggest that future detectors could help scientists create better models of hot nuclear material.

Detailed analysis of neutron star mergers

The study investigated neutron star mergers using THC_M1, a computer code that simulates neutron star mergers and accounts for the bending of spacetime due to the star’s strong gravitational field and neutrino processes in dense matter. . The researchers tested the effect of heat on mergers by varying the specific heat capacity of the equation of state, which measures the amount of energy required to raise the temperature of neutron star material by one degree Celsius. To ensure the robustness of their results, the researchers ran their simulations at two resolutions. They repeated the high-resolution run using a more approximate neutrino processing.

References:

“Thermal effects in binary neutron star mergers” by Jacob Fields, Aviral Prakash, Matteo Breschi, David Radice, Sebastiano Bernuzzi, and Andre da Silva Schneider, July 31, 2023. of Astrophysics Journal Letter.
DOI: 10.3847/2041-8213/ace5b2

“Identification of nuclear effects in neutrino-carbon interactions in low 3 momentum transfer” until February 17, 2016 physical review letter.
DOI: 10.1103/PhysRevLett.116.071802

Funding: This research was primarily funded by the Department of Energy, Office of Science, Nuclear Physics Program. Additional funding was provided by the National Science Foundation and the European Union.

This research used computational resources available through the National Energy Research Scientific Computing Center, the Pittsburgh Supercomputing Center, and the Pennsylvania State University Computing and Data Science Institute.

Source: scitechdaily.com