冷蔵剤の重要性
Hello everyone, welcome to SCIEN-SPOT. This podcast is a podcast that shines a spotlight
on the latest scientific technology from Japan. Your host is REN from SCIEN-TALK.
So, we are in a 5-part series on refrigerators this week. We benefit from the act of cooling
in various ways, from preserving food in our refrigerators and maintaining comfortable
temperatures with air conditioners, to managing medicines in hospitals and cooling data centers.
But did you know that this crucial function relies heavily on the invisible substance
called refrigerant? Refrigerants are at the heart of a mechanism called the vapor-completion
refrigeration cycle, which magically moves heat from a colder area to a warmer one.
You can think of it like a car engine running in reverse. This cycle primarily consists of
four main components, the compressor, condenser, expansion valve, and evaporator. Within this cycle,
the refrigerant repeatedly changes its state from gas to liquid and back, effectively transporting
heat. Today's topic is the journey of refrigerants. It's a grand story of how
substance developed for safety unexpectedly led to global environmental problems,
prompting humanity to search for new solutions. It truly illustrates the impact of technological
progress on the environment and how humanity has confronted and sought solutions to these
冷媒の初期と危険性
challenges. The history of refrigerants is quite a roller coaster ride. Initially,
substances like ammonia, sulfur dioxide, and methyl chloride were used as refrigerants.
While effective for cooling, they possessed highly dangerous properties
such as toxicity, flammability, and explosiveness. For instance, so many fatalities occurred due to
methyl chloride leaks that people reportedly became scared and left their refrigerators
in their backyards. Even recently, there have been reports of accidents,
including fatalities where methyl chloride was mixed into the refrigerants, falsely leveled,
and leading to explosions in refill containers. Ammonia was involved in the tragic large-scale
accident in Senegal, and early refrigerants were essentially like driving a car without brakes
incredibly powerful but extremely dangerous. And due to these dangers, an American chemist
named Thomas Midgley, in collaboration with Albert Heijn and others, developed safer refrigerants.
This led to the emergence of FRAM, also known as CFC, in the 1930s.
CFC is the abbreviation for cobalt fluorocarbons. Midgley himself famously demonstrated that the
CFCs were non-toxic and non-flammable by inhaling the gas and extinguishing the candle flame.
Their properties, non-toxicity, non-flammability, high stability,
冷媒の進化と影響
excellent thermodynamic characteristics, and low cost.
It almost perfectly meets the requirements for an ideal refrigerant.
The introduction of CFCs accelerated the widespread adoption of refrigerators and
air conditioners, profoundly impacting American eating habits and even population theft.
However, this miraculous substance had a hidden unseen poison. In 1974,
scientists Roland and Morena warned about the potential for CFCs to destroy the ozone layer,
which protects Earth from harmful UV radiation. Their predictions faced strong opposition from
the massive CFC industry at the time, which dismissed their theory as science fiction.
However, the dynamic discovery of a large ozone hole over Antarctica in 1985 provided
decisive evidence confirming their theory. The ozone layer is like Earth's natural sunscreen,
and CFCs were essential punching holes in it. This shocking discovery prompted urgent international
action, leading to the adoption of the Montreal Protocol in 1987, which phased out CFCs.
Roland and Morena were awarded the Nobel Prize in Chemistry in 1995 for their groundbreaking work.
And as a replacement of CFCs, HEFCs were introduced. Since HEFCs do not contain chlorine
and do not deplete the ozone layer, they were initially seen as a silver bullet solution.
HFCの危険性と対応
HEFC is an abbreviation for hydrofluorocarbons. However, we soon faced another unintended
consequence. It was discovered that HEFCs are potent greenhouse gases with warming potential
thousands of times greater than carbon dioxide. In response, the international community adopted
the Kigali Amendment in 2016, agreeing to phase down the production and consumption of HEFCs.
The U.S. also ratified it in 2022 and enacted domestic legislation committing to an 85%
reduction in HEFCs by 2036. The environmental impact of refrigerants
isn't just about their production. Leakage during use is also a major issue.
Globally, it's estimated that about 50% of all refrigerants leak into the atmosphere.
This also leads to significant economic losses for businesses, ranging from
hundreds of thousands of dollars annually. When refrigerants leak, a system's energy
efficiency can drop by 10 to 20%, increasing electricity costs. To address this, the proper
recovery, recycling, and destruction of refrigerants after use are extremely crucial.
低環境影響の冷媒技術の未来
The future of refrigerant technology is moving toward low environmental impact natural refrigerants
such as emerging ammonia, carbon dioxide, and propane, as well as the development of low
synthetic refrigerants like HFOs. Furthermore, innovative technologies that don't use
refrigerants at all, such as magnetic cooling and solid-state cooling, are emerging as promising
solutions. These technologies truly represent a paradigm shift in the science of cooling.
The history of refrigerants clearly illustrates the interplay between human ingenuity and the
complex chain of unintended consequences that follow. What we must learn from this journey
is the importance of adopting a comprehensive life-cycle perspective rather than focusing
on a single indicator when making technological choices. And finally, it highlights the critical
role of responsible action by researchers, industries, and each one of us. This is the
key to building a sustainable future for cooling. So that's all for today's SciencePod.
This podcast is broadcast daily on weekly and morning in both Japanese and English.
I'd love for you to listen to the podcast and post your notes and thoughts
with the hashtag SciencePod. See you next time!
