When Ammonia Ruled the World - Short #270 · HVAC School - For Techs, By Techs summary

Key takeaways

Ammonia was the dominant refrigerant in the 19th century due to its cost-effectiveness and heat absorption capabilities.
The development of R-12 and other synthetic refrigerants largely replaced ammonia in commercial settings due to safety concerns.
Environmental issues related to synthetic refrigerants led to the Montreal Protocol and a transition to low-GWP refrigerants.
Ammonia remains a key refrigerant in industrial applications because of its environmental safety and efficiency.
The refrigeration industry is evolving continuously, and adapting to new refrigerants is crucial for future safety and efficiency.

Summary

The History of Refrigeration and Ammonia

Brian takes listeners on a vibrant journey back to the 1800s when ammonia was the go-to refrigerant. The episode emphasizes its advantages: cost-effectiveness, exceptional heat absorption, and an obvious smell when it leaked, making it a favorite for breweries and cold storage plants. Despite its safety concerns, ammonia dominated until the invention of R-12, which was odorless and deemed safer yet caused its own environmental issues.

The Shift to Safer Refrigerants

As public safety concerns grew due to toxic refrigerants like sulfur dioxide and methyl chloride, the introduction of R-12 marked a pivotal shift in refrigerant technology. This section highlights how Thomas Midgley and his team created Freon to meet the demand for non-toxic solutions, leading to the decline of ammonia in residential systems, even as it thrived in industrial applications.

Environmental Impacts of Refrigerants

The discussion shifts to the environmental impact of past refrigerants, particularly the harm caused by chlorine compounds to the ozone layer. The Montreal Protocol was introduced to phase out harmful substances, leading the industry to consider alternative refrigerants with lower global warming potential. Ammonia remained a staple due to its eco-friendly properties.

Ammonia's Reign Today

Despite the emergence of alternatives, ammonia remains prevalent in large-scale refrigeration systems. Its efficiency and low environmental impact are emphasized, alongside its historical roots as a refrigerant. The segment addresses modern systems’ safety measures, noting that ammonia is still self-detecting and thus safer than many synthetic options.

Future of Refrigeration Technology

Closing the episode, Brian discusses the advent of new refrigerants like propane, CO2, and HFC blends, highlighting the continual evolution in the industry. Each shift offers promise but also requires adjustments in training and knowledge for technicians. The episode wraps up by reaffirming the importance of respecting historical refrigerants like ammonia and learning from past challenges.

Show notes

In this short podcast episode, Bryan takes us on a history journey back to when ammonia ruled the world.

In the mid-1800s, before R-12, many inventors and scientists experimented with vapor-compression refrigeration systems to make ice. They used a variety of refrigerants in their patents, including ether, ethyl ether, carbon dioxide, sulfur dioxide, methyl chloride, and ammonia. Each one had tradeoffs, but ammonia was the favorite because it was inexpensive, very good at moving heat, and useful because its odor made leaks obvious (although it was toxic and irritated the lungs and mucus membranes).

Toxic refrigerants, particularly sulfur dioxide and methyl chloride, were common refrigerants but had plenty of negative press due to the many deaths they caused. In response to the public's reservations about toxic refrigerants, Thomas Midgley from General Motors (who developed leaded gasoline) teamed up with Charles Kettering and DuPont to find a refrigerant that was non-toxic, non-flammable, and non-corrosive. In 1930, they announced dichlorodifluoromethane, also known as R-12 (a CFC) and trademarked as Freon. This refrigerant was non-toxic, non-flammable, and had no odor, and it effectively replaced the methyl chloride, sulfur dioxide, and ammonia.

However, many decades later, scientists discovered that chlorine-bearing compounds were destroying the ozone layer. To combat the environmental damage, many nations signed the Montreal Protocol in the 1980s, which would effectively phase out R-12, R-11, and other CFC refrigerants. Over time, the regulations have tightened on HCFCs and high-GWP HFCs, leading us to where we are now with lower-GWP A2L HFCs and HFO blends. As with the old refrigerants, each refrigerant had a tradeoff.

Meanwhile, this whole time, ammonia never became truly obsolete and quietly remained the lifeblood of industrial refrigeration, and it also had no global warming potential OR ozone-depletion potential. Ammonia systems run with relatively little charge, especially when paired with CO2, and ammonia is still a powerhouse today because of its chemical formula (NH3), good compression ratio, and excellent latent heat of vaporization.

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When Ammonia Ruled the World - Short #270