History of Refrigeration
There is hardly an area of our modern society not influenced by industrial refrigeration. From the foods we eat, to the buildings we live and conduct business in, to the movies we watch – refrigeration makes many of the things we consider necessities in our modern world possible. This page will give you a brief history of refrigeration and ask you to consider how your daily life would look if we didn’t have the refrigeration technology we have today.
A common misconception about refrigeration is that it is used to cool a room or a product. In fact, the cooling of these things is a by-product of refrigeration’s real purpose – which is to remove, or transfer, heat. What we call cold, then, is simply the absence of heat. Mechanical refrigeration then, transfers heat from a given location (a room) so the temperature level of that space drops.
Since the 1500’s societies have recognized the convenience of cooling down food and beverages. Colder foods lasted longer, and colder beverages sold more goods than warmer ones. This, in turn, led to less spoilage and vendors being able to sell a higher portion of their food supplies. It also led to fewer illnesses from bacterial infections caused by eating spoiled food. In short, cooling food and beverage was good for the economy and physical health of society. Since pasteurization had not been invented yet, the most efficient way to prevent the spread of illness through spoiled food, it was soon learned, was through the cooling process, which either killed the bacteria that caused illness, or stopped it from growing. This also led to lower food prices and shortages.
Evaporative Cooling – Using Water to Cool
India first developed a cooling process whereby heat was rapidly removed from a space using water. They used a process called evaporative cooling. The basic scientific observation was that rapidly evaporating liquid needs a lot of kinetic energy in order to turn from liquid to vapor form. As the liquid turns to vapor it uses the heat from the atmosphere in the room to fuel its transformation. Thus, as the heat is used it is removed, or transferred, thereby resulting in lower room temperatures.
By the 1600’s chemicals were being added to the water to further reduce the temperature of the water allowing for even more heat to be used when the liquid turned to vapor. The process used primarily to cool drinks and smaller products, but not entire rooms. The beverages were swirled in the water until they rapidly cooled. This led to an increased demand in colder beverages, and created the first commercial demands for refrigerated products.
By the late 1790’s America businesses began harvesting ice from local waterways and keeping it in ice boxes – cold rooms where it could be sold to the general public for a wide variety of uses. This same technique of evaporative cooling was used to keep these rooms cold enough to store the ice until it could be sold. That was not a major obstacle for the northern states that had an abundance of ice in the winter months that could be harvested and stored throughout the year, but led to an imbalance in the southern states that did not have such a large natural supply of ice. Northern business owners addressed this market imbalance by shipping ice from the north to the south and storing it in icehouses.
The first major obstacle to that market strategy, however, was that nearly two-thirds of the ice melted as it was shipped from the northern to the southern states. The industry, if it were to survive, had to find a way to preserve more ice through the long trips, as it was not economically viable to lose such a large percentage of their produce (ice) and still sell it at a price the American public could afford.
During the early 1800’s ice suppliers began experimenting with insulation as a way to deliver more ice from the northern states to the southern states. Their efforts led to a substantial reduction in melted ice, and made shipping ice a financially viable business. Other innovations in ice harvesting and movement techniques, allowed the ice business to rapidly grow in the United States through the mid-1800’s.
As the industry grew, however, finding pristine ice in the industrial booming northern states became difficult. The industrial revolution led to the dumping of by-products of manufacturing into waterways, thus contaminating the ice. Something had to be done.
Using Vapor Instead of Water as a Coolant
The first design for a refrigeration machine using vapor instead of water was introduced in the early 1800’s. The design was never built, however, and it collected dust until an outbreak of yellow fever in the mid-1800’s. A doctor in Florida built a refrigeration machine that was largely similar to the design invented nearly forty-five years earlier. The doctor patented his design in 1851.
The process condensed the air using gas and sent the now condensed air through a series of coils. This lowered the temperature of the air. Expanding it on the other side of the coils lowered the air temperature further. The process was so successful the doctor quit practicing medicine and focused all of his professional endeavors on creating more efficient refrigeration methods, and developing markets for his designs.
Competing designs were being developed in England and France both before and during this time frame. One system used ammonia, while the other used an ammonia/water mixture to cool the air. The ammonia/water concentration allowed for the creation of portable refrigeration units. This led to another rapid expansion of the refrigeration industry. The creator of this method was Carl von Linde, and his research led to the creation of the Linde technique, which in turn led to the first liquefaction of large quantities of air. Suddenly, the refrigeration industry was out of its infancy, and it was both financially and commercially viable on a grand scale.