History and Basics of Refrigeration
Pioneers of refrigeration
The modern world is impossible to imagine without refrigeration. The Internet, food transportation, medical imaging, and vaccine research, such as COVID-19, relies on refrigeration to function. Even the sprawl of cities across the American south in the 1950s was inconceivable without refrigeration and air conditioning. So if you like vacationing in Vegas or taking the family to Disney World, you have refrigeration to thanks. The history of refrigeration in many ways mirrors the history of America.
For people who live in warmer climates, refrigeration is considered a life-or-death matter. It’s perhaps poetic, therefore, that among the first uses of refrigeration in America occurred after the assassination of President James A. Garfield. Four months into his first term, Garfield was fatally shot by Charles Guiteau, a madman who despised Garfield for failing to grant him a position in his cabinet.
Guiteau shot the President with a revolver at the Baltimore and Potomac Railroad Station on July 2, 1881. Garfield was seriously injured and carried back to the White House, where naval engineers quickly rigged a rudimentary air cooling system using millions of pounds of ice and legions of fans to circulate the cooler air around the weakening president. While the hypothesis behind this treatment, that cooler temperatures decrease infection and contagion, was valid, the President still died 79 days later on September 19, 1881.
The principles informing the decision of Garfield’s doctors, and furthermore the development of modern refrigeration, originated in the work of a humble physician in a little-known hamlet on Florida’s Gulf Coast, Apalachicola. Born on the island of Nevis in 1802 and completing his medical education in New York, John Gorrie moved to Apalachicola because of his passion for treating tropical diseases. While modern science has discovered mosquito-borne bacteria to cause malaria, through the first part of the 19th century the disease was blamed on climate, hence the term “malaria,” Italian for “bad air.”
Gorrie foresaw the beneficial impact cooler temperatures would have on his patients and invented what he called an “ice machine” by stacking bricks of ice ordered in a basin suspended from the hospital ceiling. This represents an open system of refrigeration as opposed to closed. Unfortunately, the medical community didn’t support his efforts and he died, humiliated, bankrupt, and alone, in 1855. Later recognized for his prescient efforts in modern refrigeration, he was memorialized by Florida in 1914 when sculptor C.A. Pillars created a monument of him located in the National Statuary Hall Collection.
Like many American inventors, Gorrie’s work was anticipated by Benjamin Franklin, who discovered that evaporation of alcohol could freeze water, an insight that led to the synthesis of Freon in 1926. Renowned scientists such as William Cullen, Robert Faraday, and Jacob Perkins also contributed to the development of refrigeration and air conditioning, with Perkins, who patented the first “air conditioner” in 1835, celebrated as the “father of the air conditioner.”
The twentieth century witnessed the transformation of refrigeration and air conditioning experiments from an area of scientific research to a money-making endeavor. In 1902, Willis Carrier of the Buffalo Forge company constructed an “air conditioner” using cold groundwater, not compression, and began to sell it on the open market a bit later once the amazing comfort ramifications became clear. By the 1950s, air conditioning and refrigeration were a staple of American life, introducing pivotal changes in the way food was preserved, computer servers were cooled, and even playing a role in the creation of “galactic cities” in hotter climates, such as Houston, Las Vegas, Phoenix, Tampa, and Los Angeles. Today refrigeration and air conditioning are central to protocols in quantum mechanics, computer science, the Internet, space exploration, and vaccine development, in addition to our good old domestic air conditioners and refrigerators. Consider this: without refrigeration, you wouldn’t have had any beer to drink during quarantine.
Core principles of modern refrigeration
It’s amazing to think that the principles behind our every day refrigeration and air conditioning practice were there, in utero, hundreds of years ago in the minds of Ben Franklin, John Gorrie, and President Garfield’s doctors. The first and most important of these is the distinction between open and closed refrigeration and the related issue of compression refrigeration and alternate forms of refrigeration.
Compression refrigeration (also known as “closed-cycle compression refrigeration” and “vapor-compression refrigeration”) is the most common form of refrigeration in modern times.
Compression refrigeration is an entirely mechanical process. Whereas some open systems exploit flow of air or wind, compression uses piping and circulation of a refrigerant through component parts. This type of refrigeration consists of a compressor, a condenser, a metering device, and an evaporator. Their purpose is to regulate the flow of the refrigerant, changing phase states to create energy. Each component has its own role to play:
- Compressor: A pump that moves the refrigerant throughout the system by putting pressure on the gas. As the gas is compressed, its temperature increases.
- Condenser: A coil that receives gas (or vapor) from the compressor and removes heat from it to some other medium (often air), thus affecting a phase event change from gas to liquid.
- Metering Device/Expansion Device: This device can take a number of shapes, including a 1) thermostatic expansion valve; 2) capillary tubes; 3) fixed orifice pistons; and 4) a range of other non-conventional metering devices uses in specialties, for instance, floats or distributors. Regardless of the specific device modality, the purpose is to measure and respond to the refrigerant temperature as it exits the condenser and prepares to efficiently enter the evaporator.
- Evaporator: The evaporator is where the actual cooling effect occurs. It accomplishes this by transferring heat from the substance to be cooled (beer, vaccine cultures, computers) to the refrigerant, thus removing heat from the substance. After a phase change, the refrigerant leaves the evaporator in a vapor state to be pressurized again cyclically by the compressor.
Refrigeration and air conditioning
While refrigeration and air conditioning are related, there are important functions and applications that separate one from the other. Refrigeration denotes the transfer of heat from an undesirable location to a desirable one. Heat always transfers from warm to cold. This means, importantly, that refrigeration consists, not of adding cold to a substance, but of removing heat from it. When you place a lukewarm beer in the refrigerator, you are putting that into a location where heat will be removed from it, thus cooling it.
Air conditioning refers to the continuous process of regulating temperature, humidity, ventilation, and filtration. Its goal is to increase comfort by moving hot air from inside to outside, thus cooling the inside. In addition to increasing environmental comforts, air conditioning also makes the air safer to breathe and reduces humidity levels to prevent the development of mold and spores in the home. The invention of air conditioning, derived from the concept of refrigeration, was essential to the thriving of southern cities like Houston, New Orleans, and Miami.
Contemporary applications of refrigeration
Refrigeration is central to many of the most critical industries and technologies in the 21st century. You wouldn’t be reading this article if data servers weren’t kept cool by computer room air conditioning units (CRACs). In the medical field, imaging technologies, vaccine cultures, and organ transplants would be impossible without refrigeration. Potentially lethal food-borne illnesses such as staphylococcus aureus, botulism, e.coli, and trichinosis have almost been eradicated due to food safety and preservation techniques allowed by refrigeration. Even the Cold War.. if unintentionally, owes its nickname to the refrigeration required for Kennedy’s New Society, where missiles, space travel, and nuclear storage required the temperature and energy stability provided by refrigeration.
Since the early 19th century, refrigeration has developed from a scientist’s toy to a moneymaker’s dream to a technological necessity. However, in recent decades climatologists have discovered convincing correlations between the use of certain cooling procedures and refrigerants (CFSs, HCFCS) and climate change. As a result, modern refrigeration companies have began researching solid-state and magnetic-based technologies to reduce environmental impact. Overall, these systems harken back to the more “open” systems pioneered by Gorrie and Carrier, as well as Einstein’s pipe dream of “green” refrigeration and air conditioning. Modern refrigeration experts encourage us to look back to look forward.
In HVAC and refrigeration the past is interesting and complex and the future is bright.