HVAC School - For Techs, By Techs
Absorption Cooling - The Rise and Fall and Rise - Short #272
· Summarized
Key takeaways
- Absorption cooling technology historically relied on heat instead of electricity and was widespread before the rise of electric solutions.
- Ferdinand Carré's ammonia-water absorption machine, invented in 1859, revolutionized cooling with fire-powered refrigeration.
- Efficiency and maintenance issues led to the decline of absorption systems in favor of electric chillers.
- Modern energy concerns and waste heat utility have sparked renewed interest in absorption refrigeration.
- Future developments may bring a resurgence in absorption systems as innovations in technology merge old principles with new efficiencies.
Summary
Introduction to Absorption Cooling
In this episode of HVAC School, Bryan dives into the history of absorption cooling, detailing its rise, fall, and potential resurgence. The discussion kicks off with some personal remarks about the cold weather affecting Bryan's voice.
Historical Development of Absorption Refrigeration
Bryan explores the early 1800s, where notable figures like Michael Faraday laid the groundwork for understanding heat absorption. He highlights Ferdinand Carré's invention in 1859, a machine that created a self-contained refrigeration cycle through heat, without relying on electricity.
Decline and Niche Survival of Absorption Technology
With the advent of electric compression systems in the 1920s and 30s, absorption refrigeration began to fall out of favor. Absorption units, while reliable, were seen as outdated, bulky, and complicated compared to the rising popularity of electric-powered systems.
Modern Relevance and Revival
As energy concerns grow, interest in absorption chillers is being rekindled, notably for their ability to utilize waste heat. Bryan discusses modern applications of these systems alongside their historical roots, suggesting a potential future where they complement electric systems.
The Future of Cooling Technologies
Bryan predicts an exciting horizon for cooling technologies, including compact absorption modules and advancements in solid-state heat movers, hinting that the next revolution might be about revisiting older, less electrified methods of cooling.
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Show notes
In this short podcast episode, Bryan goes on another history journey, retelling the story of the rise and fall and rise of absorption cooling. Some of the first HVAC/R engineers cooled buildings with fire; they used absorption refrigeration, which ran on heat instead of electricity.
In the early 1800s, French scientist Michael Faraday showed that gases like ammonia could absorb heat as they evaporated. Instead of compressing the vapor, engineers looked for a way to absorb the heat from the vapor and drive it back out. In 1859, Ferdinand Carré invented a machine that boiled ammonia, absorbed the vapor into water, and reheated the mixture to desorb the ammonia, creating a self-contained refrigeration machine powered by heat alone (including waste steam from boilers). This ammonia-water absorption machine could freeze water and chill brine, and it became popular in the 1880s.
An absorption system has an evaporator that boils refrigerant, which is then absorbed into another liquid and creates a strong solution. Heat drives refrigerant back out of the solution as a vapor, where it is then condensed back to a liquid and metered. However, while they were reliable, they were heavy, expensive, and slow to respond. In the 1920s and 1930s, the rise of practical sealed electric compression systems began replacing absorption refrigeration infrastructure. By the mid-1900s, absorption chillers were replaced in all but a few applications.
Absorption didn't completely vanish, in part thanks to Servel, which continued manufacturing absorption refrigeration systems for industrial applications and rural areas with unreliable electricity. By the 1960s, Japan and Europe refined the design with lithium bromide instead of ammonia. Absorption chillers are still present, but their complexity, maintenance demands, and poor efficiency still make them impractical for most refrigeration purposes. However, with concerns about the electrical grid and decarbonization initiatives on the rise, absorption refrigeration in hybrid systems with improved efficiency and a heat source obtained from gas turbines and biomass boilers looks promising.
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