The advance in mechanical technology that brought us refrigeration back around the turn of the 20th century changed peoples lives and industry in many ways, most of them positive.
It is an interesting subject that demands an important place on this website. To that end, I have created this category (and its main page here) to look into the subject.
What is Refrigeration?
The term refrigeration refers to cooling a space, substance or system in order to reduce or lower and/or maintain its temperature at some point below the ambient one. In straight talk, "refrigeration" is simply artificial cooling or temperature reduction.
In its earliest form, people used to pack ice around the things they wanted to preserve at low temperature for any given length of time.
People kept food in iceboxes that had to be periodically replenished with fresh ice as when was there melted. This gave rise to an industry providing ice for commercial and residential use and lasted for many years.
While this obviously worked, it was not really convenient to keep hauling ice to keep something cold for a prolonged time and people were becoming increasingly demanding of more convenient ways to do things.
A Short History Lesson
A mechanical alternative was eventually found by Scottish professor William Cullen, who, as long ago as 1755 designed a small experimental refrigerating machine. Cullen used a pump that created a partial vacuum over a container of diethyl ether. The liquid then boiled, causing it to absorb heat from the surrounding air. That experiment also created a small amount of ice. However, at that time it had no practical application.
The baton was taken up by Benjamin Franklin in 1758 who, while collaborating with John Hadley, professor of chemistry at Cambridge University on a project to investigate the principle of evaporation as a means of rapidly cooling an object down past the freezing point of water, discovered that evaporating volatile liquids like ether or alcohol would achieve this.
Later, in 1820 Michael Faraday used high pressures to liquefy ammonia which lead Jacob Perkins to build the very first closed-cycle, continuously operating vapor-compression refrigeration system that he patented. It was, however, not commercially viable and the prize for the first commercially successful patent for a practical vapour-compression refrigeration system went to British journalist, James Harrison in 1856.
The Heat Exchange Process
The refrigeration process that we all know is basically a heat exchange process. Heat energy is taken from a reservoir and its temperature lowered, while being transferred to another reservoir where its temperature is raised.
To achieve this, modern refrigeration devices employ a refrigerant gas that can be compressed to raise its temperature and then condensed to lower it. This all happens inside the cooling mechanism behind the unit (fridge).
Why Do We Need Refrigeration?
The need to preserve food for longer in an enclosed space (the modern domestic fridge or larger commercial equivalents) as well as to cool indoor spaces when the temperature becomes uncomfortably hot during the summer months in most climates (air conditioning) led to the discovery and production of refrigerant devices in a number of sizes for various applications.
For industry, it means being able to preserve food and other heat sensitive products much longer than they would last if left normal room temperature. For domestic use, it enables families to store food in the fridge for days or even weeks that would otherwise spoil very quickly if left in the open air.
Starting with the common fridge that stores food at a low enough temperature to keep it fresh without it getting too cold and ultimately freezing, then moving onward to appliances that store food at a freezing temperature in order to store it for much longer.
In the associated articles under this section, I'll be looking at a number of different refrigerating devices and appliances for home and industrial use. I'll be reviewing and recommending selected models based on my own research and experience and presenting them to you in a series of review articles.
The article titles appear below and each one can be clicked to open the full article.