How Do Refrigerants Actually Work?
Water boils at 100°C, as everyone knows. Inside the water, there are numerous molecules moving rapidly, similar to ping pong balls in motion. The hotter the water, the faster they move. At the water's surface, air molecules act like a lid, preventing the excited water molecules from escaping. Any overly excited water molecules attempting to escape are forcefully pushed back down by the air molecules, reminiscent of the game whack-a-mole.
As the water heats up, the molecules move faster, constrained by the air above. However, if the water is heated sufficiently, the water molecules will move so quickly that they overpower the air molecules and escape. This point of escape is known as the boiling point, typically 100°C.
At higher altitudes, like the summit of Mount Everest, there is less air, meaning fewer air molecules to contain the water molecules. This makes it easier for the water molecules to escape. While I haven't been there, it's said that at Everest's summit, water boils at 80°C due to the lower pressure, which decreases the containment by air.
To recap, the boiling temperature of water depends on the air pressure above it. We could theoretically adjust the boiling point of water to our liking by altering this pressure. This principle is precisely what we utilize in refrigeration: manipulating pressure to change the boiling point.
Step 2: Instead of water, which is inefficient as a refrigerant, we use propane, or R290. Opening a can of propane causes it to boil vigorously. The propane molecules move so fast that they easily escape the air molecules above, and each escaping molecule carries away a bit of heat, cooling the propane container to -42°C.
However, releasing the propane into the atmosphere is inefficient, so we capture it. We then use a pump to compress it to 300psi and store it in a new container. At this pressure, the propane condenses back into liquid, releasing heat as it transitions from gas to liquid. This process of compression essentially squeezes the heat out of the propane, allowing it to condense at 45°C.
So, in one container, we have propane boiling at -40°C, absorbing heat. In another, we have propane condensing at 45°C, releasing heat, with a compressor between them. We're essentially moving heat from one place to another using a compressor.
Refrigeration engineers now cleverly adjust these pressures to achieve precise temperatures, but it all boils down to pressure manipulation. In your fridge, freezer, or heat pump, this is exactly what's happening. It's not complex or new. It's a beautiful example of science in action.
Heat pump expert
- 22 Forums
- 2,073 Topics
- 45.5 K Posts
- 73 Online
- 3,353 Members
Join Us!
Trusted Installers
Struggling to find a reliable heat pump installer? A poor installation can lead to inefficiencies and high running costs. We now connect homeowners with top-rated installers who deliver quality work and excellent service.
✅ Verified, trusted & experienced installers
✅ Nationwide coverage expanding
✅ Special offers available
Latest Posts
-
RE: Solar Power Output – Let’s Compare Generation Figures
Well we finished this month with an all time record! Ev...
By Andris , 6 hours ago
-
RE: 5 Star Service from Havenwise
Oh good! I was wondering when/if you might pick them ...
By Transparent , 8 hours ago
-
RE: Air Changes per Hour - ACH and the MCS requirement
update - my old installer insisted on a heat loss of 11...
By MatWin , 10 hours ago
-
I agree it's not very helpful. Generally, the max heat ...
By Old_Scientist , 11 hours ago
-
RE: Commencing on an ASHP Installation Process
I think therein lies the problem. Ratio of quotes to i...
By JamesPa , 1 day ago
-
RE: Why Your MCS-Certified Installer Might Not Be As Competent As You Think
Hive and most other smart thermostats don't play well w...
By JamesPa , 1 day ago
-
RE: Enabling WiFi: Samsung ASHP on Smart Things App
Thanks for the input. I've been running various experim...
By Grahamh-uk , 1 day ago
-
RE: Radiators downstairs are cooler at the bottom after ASHP install
@melonbuffet Hi, this sounds great is you are getting 5...
By ASHP-BOBBA , 2 days ago
-
RE: Ripped Off: How UK Homeowners Are Paying Gas Prices for Wind Energy
I believe there's another reason that network upgrades ...
By Transparent , 2 days ago
-
RE: What’s the modern take on advised types of insulation?
@jeff I am sorry @jeff if I have misunderstood what you...
By Toodles , 2 days ago
-
RE: Getting the best out of a heat pump - is Homely a possible answer?
@editor Cobbler’s Mantra that!
By Toodles , 3 days ago
-
RE: Renewables & Heat Pumps in the News
Australia Blue, the first wind farm in Western Victoria...
By Morgan , 3 days ago
-
RE: Flow rate discrepancy between ASHP and manifold
That's useful thanks, I hadn't seen that table before. ...
By AshRolls , 4 days ago
-
In principle I agree, @johnmo, but with provisos. The...
By Majordennisbloodnok , 4 days ago
-
RE: Heat pump installation and BUS Grant timings
@jamespa Thats how I understood it too. 🙂
By ASHP-BOBBA , 4 days ago
-
RE: Antifreeze top up for my heat pump - is this a rip off?
@sallyl That sounds about right if they are re-filling ...
By Brendon Uys , 4 days ago
-
I wouldn't be so sure about that. Heat pump designers ...
By JamesPa , 5 days ago
-
RE: Jokes and fun posts about heat pumps and renewables
@toodles they're a rowdy bunch!
By Mars , 6 days ago
-
RE: Home energy storage & battery register
@jamespa To a certain extent, by exporting to the grid ...
By Toodles , 6 days ago