Refrigerant
From Environment & Energy Wiki
Please help complete it, if you are able.
Description
When a gas, especially in liquid phase, is allowed to expand adiabatically in a gaseous phase, the temperature is reduced. This is the principle behind most refrigeration. The gases or refrigerants used in practice may be of a wide variety, the choice being made on the desired temperature and heat transfer capacity. Before the mid-1930s, the most popular refrigerants for temperatures between -20 °C and +5°C (e.g., for food conservation) were sulfur dioxide and ammonia. These are both highly toxic and were replaced by non-toxic CFC-11 or CFC-12, which were popular until the 1980s when concern about ozone depletion led to their control under the Montreal Protocol. They were largely replaced by a number of blends of HCFCs (mildly ozone depleting) or HFCs (severe greenhouse gases), both of which are also controlled. Later, butane and propane have also been proposed as refrigerants; this met resistance, at first, because of their flammability, but became popular when it was shown they were safe. Ammonia is still used in absorption refrigerators and for large freezer and chiller applications where appropriate safety measures are possible.
Detailed description
You can use subheadings with === Subheading text === syntax
Please remove the {{descrip}} in the Edit page
