Wheeler on HVACR: The Refrigerant Problem - Part 1
Now, I don't pretend to understand molecular bonds, but a scientist once explained how refrigerants are made this way. He said that each carbon atom can bond to four other atoms. So, methane (natural gas) is made up of single carbon atoms, which are each bonded to four hydrogen atoms. And to make R-12, for example, they strip the hydrogen atoms off of each carbon atom and bond four chlorine atoms in their place. This makes the solvent, carbon tetrachloride.
The next step is to strip two chlorine atoms off of each carbon tetrachloride molecule and replace them with fluorine atoms. So, the end product (R-12) is made up of single carbon atoms that are bonded to two chlorine and two fluorine atoms.
Now, the problem with R-12 is that the similarity of chlorine and fluorine atoms creates a very tight bond that would be indestructible, were it not for fire and the earth's stratosphere. For only the energy in fires or the hard radiation of the earth's outer atmosphere can start breaking down this molecule and strip the atoms off the carbon. Otherwise, this refrigerant (as is also true with many other chlorine-based solvents) would last and accumulate in our atmosphere forever. And even now, R-12 molecules are projected to last 100 years before they are eventually broken down and destroyed.
Free chlorine atoms in the upper atmosphere are a bad thing, because they fly around up there and remove the electrical charge from all the ozone (O3) molecules they touch, which breaks them down into regular (O2) oxygen molecules, and that allows more hard radiation to reach the earth. Also consider the fact that each chlorine atom is thought to break down an average of 60,000 ozone molecules before they fall back to the earth.
Free chlorine atoms down here on the earth never reach the stratosphere, because chlorine is highly reactive, so these atoms bond with other atoms and molecules here below that neutralize them before they can reach the stratosphere. The only way for chlorine to reach the ozone layer is in its combined form as solvents or refrigerants.
However, with HCFCs, such as R-22 and R-123, the molecular bonds aren't nearly as tight, so they tend to break down naturally before they reach the stratosphere. And that's why HCFCs aren't as dangerous to earth's protective ozone layer. The reason for this is that their molecular bonds include one or more weak hydrogen atoms, which are easily lost… and once part of the bond is broken, the entire thing starts to fall apart.
So, where are we going with this? Well, once you understand this part of the problem, you will also understand why there will be so few refrigerant options open to us in the near future. This will be the topic of my column in next month's SUPPLY HOUSE TIMES.