A class of chemicals that are commonly used as coolants in refrigerators, air conditioners and heat pumps is being eliminated by the US Environmental Protection Agency.
If that feels already seen, it ought to.
In the 1990s, these chemicals were marketed as substitutes for earlier refrigerants based on chlorofluorocarbons or CFCs called hydrofluorocarbons or HFCs. In order to protect the lives from harmful ultraviolet radiation in the sun, the CFC destroyed the high ozone layer in the Earth’s atmosphe. HFCs are significantly less damaging than CFCs, but cause another issue — they cause a strong thermal trapping effect that helps global warming.
Several states have announced plans to phase out HFCs in recent years. Following a vote in Congress, the EPA is proposing federal legislation to reduce HFC production and imports beginning in 2022, with the goal of reducing them by 85 percent in 15 years.
Let’s look at what HFCs are and what could replace them in the future.
How HFCs keep rooms and food cool
A heat pump is a type of technology that is used in refrigerators and air conditioners. Heat pumps use energy to transport heat from a cold location to a warm location, which sounds almost magical.
The following is how a refrigerator works: A fluid circulates in the refrigerator’s walls, trapping ambient heat to keep the fridge cold. It used to be CFCs, but now it’s HFCs. The liquid evaporates as it absorbs the heat. The resulting vapor is pumped to the refrigerator’s back coils, where it is compressed into a liquid under pressure. The heat absorbed from inside the fridge is released into the room as a result of this operation. Air conditioners and home heat pumps both transfer heat into and out of a house using electric-powered compressors and evaporators.
The correct fluid for the refrigerator must be chosen to find a product that can be evaporated and condensed by changing pressure on the fluid at the right temperature.
CFCs looked perfectly fit for the bill. They reacted not to corrosion of the equipment with the tubing or compressors and were not flammable or toxic.
Unfortunately, as scientists discovered in the 1980s, the chemical stability of CFCs turned out to be a problem that challenged the entire planet. CFCs that leak into the environment, often from discarded machines, stay there for a long time. They eventually reach the stratosphere, where UV radiation from the sun eventually destroys them. However, as they decompose, chlorine is produced, which interacts with the protective ozone, allowing harmful radiation to reach the Earth’s surface.
New refrigerants were produced after the use of CFCs was phased out in the 1990s to protect the ozone layer, and the industry switched to HFCs.
Why HFCs are a climate problem?
HFCs are much more reactive in air, like CFCs so they never reach the stratosphere where Earth’s protective radiation shield could be affected. They saved the world largely from the ongoing ozone catastrophe and can now be found everywhere in refrigerators and heat pumps.
But whilst the chemical reactivity of HFCs prevents them from depleting the ozone layer, they absorb much thermal radiation and become a greenhouse gas through their molecular structures. HFCs are very good for capturing infrarot photons emitted by the Earth like carbon dioxyde from steroids. Some of the radiant energy warms up the environment.Since reactive HFCs, unlike CO2, are absorbed by air chemistry, they only warm the atmosphere for a decade or two. However, a small amount goes a long way: each HFC molecule absorbs thousands of times as much heat as a CO2 molecule, making them potent climate contaminants.
HFCs leaking from discarded cooling equipment are estimated to account for 4% of global greenhouse gas emissions, which is roughly twice as much as aviation.
This is why HFCs must be phased out in favor of alternative refrigerants. HFCs have done their job in preserving the ozone layer, but they are also a significant contributor to short-term global warming, and their usage is growing as global cooling demand rises.
As the production and use of HFCs are so strong and short-lived, they can have a significant cooling effect on the environment during the next few decades, and time to buy as the world turns its fossil-fuel energy supply into a cleaner source.
The good news is that alternative coolants are available.
At room temperature, ammonia and hydrocarbons such as butane evaporate and have been used as refrigerants since the beginning of the 20th century. The gasses are short-lived, but have a negative effect. Their increased reactivity requires more corrosion resistant and leak-proofing for their compressors and plombing.
What can replace HFCs?
The chemical industry has been creating newer alternatives that are meant to be better for both people and the environment, but inert chemicals can have unintended consequences, as we saw with CFCs and HFCs. Several business leaders have backed attempts to phase out HFCs, such as the Kigali Amendment, an international agreement to limit HFC use around the world that was signed in 2016 but has yet to be ratified by the United States.
As a result, a new generation of cooling equipment is needed. Our refrigerators and air conditioners will be replaced by a new generation of upgraded items, just as our televisions, audio devices, and light bulbs have changed over the years. New refrigerators will look and function just like the ones we’re used to, but they’ll be kinder to the environment.
Source: Tech Xplore