We finished the last post briefly looking at the movie East of Eden and the loss suffered by Adam Trask when he tried to move lettuce packed with ice in a rail car in 1917. The ice melted and the lettuce rotted. Essentially, the rail car was not insulated, allowing for the rapid melting of the ice. In 1887, the first cooled shipment of fruit from California to New York was made, 28 years before the time frame of the movie. And ice cooling began a long time before that.
Food is a biological product having chemical reactions occurring almost continually. The adverb “almost” is used because the chemical processes require energy, be they processes inherent to the biology of the food itself or to the bacteria also present. Earlier than 1,000 BC (or BCE – before the common or current era), ice and snow harvesting was used. While believed to initially be used to cool beverages rather than preserve food, people obviously recognized the process of heat exchange without the need of physics or mathematics.
In the early 1,800s, ice harvesting emerged in the United States. Ice was harvested in New England and shipped south, the price dropping significantly with the invention of the horse-drawn ice cutter in 1825. Concurrently, the scientific community was exploring the process of making ice. As an aside, even Benjamin Franklin was involved in 1758. It was clearly understood that cold could make food last longer. One could rely on Mother Nature making ice or humans could use the science of heat exchange to do it themselves. But why stop with ice, why not cool the food directly with refrigeration?
Technology and its growth is a limiting factor. It was easier to make ice in an ice making plant and distribute iceboxes than to build a mechanically cold box (a refrigerator) itself. In 1913, the United States had 100,000 rail cars still cooled by ice. General Electric released the first electric refrigerator in 1927. When I was growing up, the refrigerator was still called the icebox. And in the period of 1925 to 1930, mechanically refrigerated trucks came into service primarily to deliver milk and ice cream.
In this process of what economists will call the cold chain, stuff, primarily food and pharmaceuticals, is distributed in a temperature controlled environment. It is an uninterrupted chain or series of refrigerated production, storage, or distribution activities. While we take these for granted, the key to the system was the development of mobile refrigeration, not iceboxes but refrigerators on wheels. It was the invention of Frederick McKinley Jones in 1940 and the founding of Thermo King.
While all of the steps in the process of the cool distribution of stuff were developed through observation and recognition of a need by entrepreneurs, the Second Law of Thermodynamics is a common element to be considered. Without getting too technical, heat will not travel from a cold spot to a hot spot on its own. If you drop an ice cube (lack of heat in the water) into a pot of boiling water (lots of heat in the water) the heat moves into the ice cube and melts it. If you want to go the other way, it takes a lot of work and that required energy.
In a refrigerator what is left of heat in the cold compartment is extracted from the contents of the air and stuff and moved to the hotter, outside environment. This means that the walls of the box must be cooler than the contents or cooling air must be circulated into the box. On a hot summer day if you don a wet t-shirt, the evaporation of the water from the shirt reduces its temperature – heat extraction. This is similar to what is happening in a shipping vessel using ice. The trick is to do it without ice.
In a simplistic model of a refrigeration unit, a gas is compressed which raises its temperature (and takes energy) and enters a condenser to cool down. The condenser is warmer than its surrounding environment. As the condensed gas cools, it becomes a liquid, at least partially. The liquid or liquid/gas mixture is then moved to an evaporator where it expands. While water might do this through evaporation, you need a “special” material (such as Freon) to do this in this example. When the gas expands, the walls of the vessel cool down because the liquid/gas is absorbing the heat. And air blown over the evaporator will be cooled.
The key here is keeping the stuff cool or cold during transport and/or storage is it takes energy beyond the simple process of moving it over the surface of the earth. Be it the harvesting of ice for packing, the making of ice for packing, or the creation of cooling through incorporated refrigeration, it adds to the energy needed for storage and distribution. In ice harvesting Mother Nature provides a lot of the energy, otherwise humans must find it and use it, effectively or not.
From where does the energy come? As the world population grows, do the distribution demands grow or can increases in efficiency keep things constant? And is this the only stuff that must be distributed efficiently? What about people and energy?