The next phase in new refrigerants
By Dale Yelnich
Refrigerants are one of the mainstays of our modern industrial complex. Virtually any type of cooling requires a refrigerant to function, and without refrigerant; many things we take for granted simply couldn’t exist.
But in this age of environmental awareness and regulations, refrigerants have been found to be one of the most polluting substances on our planet. CFC’s (or halogen based chlorofluorocarbon refrigerants), contribute to global warming via the depletion of our ozone layer.
They have since been regulated out and are no longer in use. Substitutes have been manufactured in an attempt to reduce the damages to the atmosphere, however most of these newer and less polluting refrigerants are stop-gap measures.
They are being used until either different refrigerants arrive, or better technology is designed to make use of harmless alternatives as refrigerant. That’s where the next phase begins.
The age of refrigerants began by using water to cool things down. Any given substance will transfer its heat to any other substance by thermal energy. A hot piece of metal will attempt to heat a cold piece of metal when placed in contact with it.
The most dedicated use of water as a refrigerant is in nuclear power plants. The reactors in a nuclear power plant use thousands of gallons of circulating water to keep the reactors from going critical. The best place to build reactors are near cold water lakes or rivers.
These open water sources act like a refrigerant when pumped through a system of tubing around the reactor, to carry excess heat away. Although this is an extremely environmentally friendly way to cool down an industrial machine, it isn’t practical except when used for a specific purpose.
But that scenario is the clue to where refrigerants are headed. Since future refrigerants are going to have to be environmentally friendly, the best alternatives are going to be naturally occurring surrogates.
The largest setbacks to using a natural refrigerant are toxicity, efficiency and cost. Modern manufactured synthetic refrigerants are efficient, have little toxicity and are relatively inexpensive. Because they are synthetic, they have been manipulated to give the most cooling effectiveness for the dollar, and are easy to work with.
Standard refrigerants like R-11, R-12 and other CFC’s have been replaced by the less ozone depleting HCFC compounds. Although still a chlorofluorocarbon based refrigerant, the addition of the hydrogen molecule makes the CFC compound break down faster before it reaches the ozone layer. While they are not perfect, HCFC’s like R-123, have less global warming potential and they are less volatile in the upper ozone atmosphere.
All HCFC refrigerants are scheduled to be staged out of new equipment by 2020, and completely removed by 2030 in all equipment. By then, future refrigerants will have to take up the slack, yet be environmentally friendly doing it.
There are contenders on the horizon, that you may or may not have heard of or even considered, and they are predominantly in the non-halogenated class. Flammable gases, like propane and butane, are viable options that are common and readily available, and they don’t pollute the atmosphere. The two main concerns are cost to use them, since they are a carbon based fuel, and the fact that they are highly flammable. Any gas leak, around an electrical system that might cause a spark, could be catastrophic.
Ammonia and its cooling properties have been known for centuries. It is very inexpensive, environmentally friendly, and only slightly flammable. However, if an ammonia-based refrigeration system ever broke down and leaked, the entire commercial building that the unit served would need to be evacuated. That’s not good for business.
Carbon dioxide based refrigerants are also showing some promise. They aren’t flammable and they are environmentally friendly, but cost and efficiency are the major hang ups for allowing a carbon dioxide based refrigerant to becoming a widely, and cost effectively, used alternative.
That brings us back full circle to the most basic of all refrigerants, water, or more correctly known as R-718. Water vapor has been used for years in Europe as an environmentally friendly and inexpensive refrigerant. The problem with R-718 is not in the substance itself, but in the machinery that turns it into a useful cooling medium.
A special type of titanium bladed turbine compressor is needed to achieve the right pressure for adequate refrigeration. In Europe, where energy prices are more expensive than in the United States, the machinery to turn water into a viable refrigerant is cost effective. In the States, it isn’t.
That doesn’t mean that the cost of the machinery, or other ways to pressurize water, won’t be attainable or won’t ever be cost effective, but until that time comes and for now, the use of water as a cooling agent isn’t going to happen. But with advancements in machinery that are less costly to manufacture, water may become the ultimate next phase in refrigerants.