Today our hosts Ray and Sunny discuss the developments of using ammonia and propane in refrigeration that resulted in a large part from the experiments of Michael Faraday and followed up by the contributions of others to catapult mankind forward to much safer and healthier food storage opportunities. The propane refrigerators we sell at BensDeals.com use ammonia vapor produced by burning propane to complete an absorption cooling process that uses no compressor or outside power source making them perfect for off-grid applications. Later propane has been used as a refrigerant instead of a fuel source in vapor compression cooling systems. Thanks for joining us in this short but fascinating walk down memory lane.
Transcription:
Do you ever think about how we keep food from going bad
or just walking into a nice cool room
on like a crazy hot day with refrigeration,
but we just kind of take it for granted, right?
It's true.
We don't always think about the how and the why
behind things we rely on every single day,
and I'll tell you what the science and history
behind refrigeration, it's actually a lot more fascinating
than most people realize.
There are some really cool stories buried in there.
Yeah, for sure.
And today we're gonna take a deep dive
into a very specific part of that story,
the evolution of propane as a refrigerant.
We've got some great source material
that goes all the way back to the early days
of like messing around with gases in the lab
and how that eventually led
to the cooling systems we have now.
Exactly, and it all really starts with this idea
of liquefying gases, which might seem completely unrelated
to your fridge at first, but stick with us here
because it gets pretty interesting.
We'll be looking at Michael Faraday's work,
which was absolutely foundational,
and then we'll touch on ammonia's role
in the early days of refrigeration,
and then of course the overall impact this tech has had.
I mean, it's hard to overstate
how much it's changed our lives.
Right, and we know you, our listeners,
wanna get the most out of this deep dive,
so we're gonna keep things clear and engaging.
We'll hit the high points without getting too bogged down
at the technical details.
Absolutely, we'll be your guides through this journey,
through the history of refrigeration.
Alright, so let's start at the beginning
with a name most of us probably remember
from high school science class, Michael Faraday.
Now, he's mostly known for his work
with electricity and magnetism,
but his interests were actually way broader than that.
Yeah, a lot of people might not know this,
but Faraday was super curious
about all sorts of scientific questions.
In the early 1800s, he was doing some groundbreaking work
on how gases behave, and this might seem
totally separate from refrigeration,
but it turns out it was absolutely crucial
to how everything developed.
So what were some of the key things he discovered
that laid the foundation for all this?
Well, in 1823, he did these really clever experiments
where he managed to liquefy gases like ammonia and chlorine,
and the way he did it was by using a combination
of pressure and cooling,
and here's the really important part.
He noticed that when these liquefied gases evaporated,
they actually absorbed heat from their surroundings.
This cooling effect is literally the core principle
behind how your fridge and your air conditioner work.
So you're saying that simple process of liquid
turning back into gas is the whole secret
behind keeping our groceries cold.
Pretty much Faraday showed that you could control temperature
by manipulating the state of a substance,
and this whole thing became the basis
for something called the vapor compression
refrigeration cycle, which is still
the main technology used today.
It's amazing to think he wasn't just coming up
with theories about gases,
he was actually changing them into liquids
and seeing that temperature drop firsthand.
Now, you mentioned other scientists
like Dalton and Priestley earlier.
How does Faraday's work fit in with what they were doing?
Right, so those guys,
they'd already done a lot of work on gases,
like figuring out the gas laws
and really carefully studying their properties.
But Faraday, he took things a step further.
He was the one who showed that you could use pressure
to actually change the physical state of a gas,
turning it into a liquid,
and he recognized the practical potential
of that transformation.
Okay, so we've got Faraday showing us
that you can liquefy gases and get that cooling effect.
So how did we go from that lab experiment
to the refrigerators we see everywhere today?
Well, one of the first gases they actually started using
for refrigeration building on Faraday's work was ammonia.
It had some properties that made it a really good fit
for these early systems.
Ammonia, huh?
I always think that really strong smell.
Did they use that all the time for refrigeration back then?
Yeah, for a while it was a big deal,
especially for industrial refrigeration,
for keeping things cold on a large scale.
In 1876, there was this German engineer
named Karl von Linde.
He actually built the first practical
and efficient refrigeration system that used ammonia.
So he basically took Faraday's basic principle
and turned it into a system
that could produce cooling reliably and continuously.
And that had a huge impact
on things like the meatpacking industry.
They could suddenly store food for longer
and ship it further.
It really changed things.
So how did Linde's system actually work?
It was based on that vapor compression cycle
that we were talking about earlier.
So they'd take ammonia gas and compress it,
which basically squashed the molecules closer together
and increased the pressure and the temperature.
And that caused it to condense into a liquid,
but a high-pressure liquid.
Then they'd run this liquid through a special valve
or a small opening that would make the pressure drop
really quickly.
And when that happened, the liquid ammonia would evaporate
and as it evaporated,
it would suck the heat out of its surroundings.
That's where you get the cooling effect.
Linde's system made this whole process
continuous and efficient,
which is why it was such a game changer.
That makes a lot of sense.
You compress it, cool it down,
let it expand and evaporate,
and it takes the heat with it.
It sounds pretty straightforward,
but I bet the actual engineering involved
was crazy complicated for that time.
Now you also mentioned something called
absorption refrigeration, which also used ammonia.
How is that different from the vapor compression system?
Absorption refrigeration is super interesting
because it doesn't use a mechanical compressor
like the other one.
Instead, it uses heat as its main energy source.
And yeah, ammonia is still a key player
in this whole thing.
So you're telling me they were using heat to create cold?
That sounds kind of backwards.
How does that work?
It all comes down to the chemistry of ammonia
and another substance, usually water.
You see, ammonia has a really low boiling point,
like minus 33 degrees Celsius.
And it also has what's called
a high latent heat of vaporization.
That basically means it can absorb a ton of heat
when it evaporates, which makes it really good
at cooling things down.
So in this system, the water acts like a sponge.
It absorbs the ammonia gas.
Okay, so the water sucks up the ammonia.
Where does the heat come in?
This is where it gets really clever.
They would apply heat to the ammonia water mixture,
and that heat could come from all sorts of sources,
like natural gas, propane, or even solar energy.
And because ammonia is more volatile,
it evaporates more easily.
The heat would basically force the ammonia out of the water.
So now you've got ammonia vapor,
which they would then condense into a high pressure liquid,
kind of like in the other system.
And then just like before,
they'd run that liquid through a valve.
It would expand, evaporate, and bam,
you've got your cooling effect.
And the leftover water that's now got less ammonia in it,
well, it goes back to absorb more ammonia,
and the cycle starts all over again.
The really cool part is you don't need
a noisy mechanical compressor at all.
So they figured out how to use heat
to separate the ammonia
and get the whole cooling process going.
Yeah.
That's pretty ingenious.
Where did they use this absorption
refrigeration stuff back then?
It was great for places where electricity
was hard to come by or unreliable,
like those old gas-powered refrigerators,
especially the ones you'd find in RVs
or in places off the grid.
They used absorption systems a lot
because all they needed was a fuel source.
And they're actually still used
in a bunch of those situations today
because they're really dependable.
That's a really cool example.
Yeah.
So we've been talking a lot about ammonia,
but as you mentioned, it does have some safety issues.
And that brings us to propane.
When did that enter the picture as a refrigerant?
Well, you know, scientists and engineers,
they're always looking for ways to improve things,
and safety is a big deal.
So they were trying to find something
that could cool as well as ammonia, but without the risks.
And around 1910, a guy named Walter O. Snelling,
he identified propane as a potential option.
1910.
Wow, so it took quite a while after Faraday's discoveries
for propane to even get noticed.
What was it about propane that made it seem
like a good choice for a refrigerant?
It took a bit of time for people
to really catch on to propane's potential,
but by the 1920s and 30s,
it was starting to get some serious attention.
Researchers figured out that it had
these really good thermodynamic properties,
which made it great for refrigeration.
You know, things like its boiling point,
which is minus 42 degrees Celsius.
That's perfect for a lot of cooling applications.
And when we talk about thermodynamic properties,
we're basically talking about how well a substance
can absorb and release heat,
which is really important
for making cooling systems efficient.
I'm guessing the big advantage over ammonia
was that propane wasn't toxic, right?
You got it.
That was the key difference.
Propane's non-toxic, which made it way safer to use,
especially in homes and businesses
where a leak could be really dangerous.
Ammonia, you gotta be really careful with it
because it can cause some serious problems if it gets out.
So it sounds like that non-toxic aspect of propane
is really what made it possible
to use in our everyday appliances.
Absolutely.
By the mid-20th century, they were putting propane,
which is often called R290 in the refrigeration world,
into all sorts of things,
like fridges, freezers, and even air conditioners.
And something interesting is that
even though they didn't know everything
about environmental impacts back then,
propane turned out to be a better choice
than some of those synthetic refrigerants
they developed later, CFCs, for example.
Those stuck around in the atmosphere for a long time
and caused some real damage to the ozone layer.
But propane, it breaks down pretty quickly
because it's a natural hydrocarbon.
Right, CFCs turned out to be
a pretty big environmental problem.
So was propane seen as a greener option even back then?
Well, the main reasons they started using propane
were that it was safe and it worked really well.
But because it's a natural substance,
it didn't have the same ozone depleting properties as CFCs.
So yeah, looking back, it was definitely a step
in the right direction for the environment,
even if they didn't completely realize it at the time.
It's kind of crazy how all these things connect.
You've got these basic gas laws
being figured out in the 1800s,
then concerns about safety,
and then later on the whole issue
of how refrigerants affect the environment.
It's all part of this bigger story.
Now we've talked about the science and the history,
but what about the real world impact of all this?
How has refrigeration changed our lives?
I mean, it's been a total game changer.
We wouldn't have things like air conditioning refrigerators
or freezers without this scientific breakthroughs
we've been talking about.
And those technologies, they're not just conveniences.
They affect everything from how we store and transport food
to how we live and work in different climates.
It's hard to imagine modern life without them.
Seriously, try to imagine a scorching summer day without AC.
It's just not something most of us would want to deal with.
And propane, it's still being used
in a lot of AC units today, isn't it?
Yeah, definitely.
Because it has a low global warming potential
and it's really efficient.
A lot of people consider it a better alternative
than some of the synthetic refrigerants,
so it's still going strong
as a good choice for cooling systems.
Yeah, and we mentioned earlier
that both propane and ammonia have been used in fridges
over the years, right?
Yep.
For the most part, they don't use ammonia
in home fridges anymore because of the safety concerns,
but it was used in some older models
and it's still used in some industrial applications.
But for home fridges and freezers,
propane became the go-to choice because it was much safer
and it's still widely used today.
What about for things that need to be kept really cold,
like those big freezers you see
in grocery stores and restaurants?
Does propane work well for that?
Absolutely.
Propane is actually perfect for deep freezing
because of that low boiling point we were talking about.
It can keep things super cold without breaking a sweat,
which is really important for commercial
and industrial freezers.
So when we step back and look at the big picture,
this whole history of developing different refrigerants,
it's had a pretty big impact on the environment, right?
Oh yeah, for sure.
Early on, they used refrigerants like CFCs and HCFCs,
but as scientists learned more about them,
they realized they were really bad for the ozone layer
and they contributed to global warming.
So a big shift happened and we started phasing out
those harmful refrigerants and switching
to more environmentally friendly options
like propane and ammonia.
That was a huge step forward in protecting the planet.
And propane is considered a really good option
for the environment, right?
Exactly, it has almost zero ozone depletion potential
and it's really low on the global warming scale.
Plus, on top of just choosing the right type
of refrigerant, there's also a lot of work being done
to make the whole refrigeration system itself
more efficient.
Things like variable speed compressors,
better insulation, and even smart technology
that can control things more precisely
are all helping to make refrigeration more sustainable.
Okay, so let's recap.
We started with Faraday just messing around
with gases in his lab,
then we had ammonia taking center stage
and then propane emerged as a safer
and better option for the environment.
And now it's still playing a key role
in keeping things cool in a sustainable way.
What a journey.
I know, right?
It's amazing to think about how these basic
scientific discoveries back in the 1800s
have shaped so much of the world we live in today.
It really shows how important it is
to keep asking questions and to never underestimate
the power of science.
And it wasn't just about finding ways
to make things colder.
It was about making it possible to store food safely
on a large scale, preventing all that waste,
and even making it possible for people to live comfortably
in all kinds of climates.
And with climate change becoming such a big issue,
this whole story is far from over.
There's so much more to learn and to do.
And that brings us to a question for you, our listeners.
Think about this incredible journey from Faraday's lab
to the propane that might be in your fridge right now.
What other simple scientific discoveries
might be out there waiting to be made
that could change the world in ways
we can't even imagine yet?
And as we keep pushing for better, more sustainable
cooling technologies, what role will propane
and other natural refrigerants play in that future?
It's definitely something to think about.
Absolutely, lots to ponder.
So until next time, keep those brains buzzing.
And stay cool out there.
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