Originally Posted by capta
As mentioned above, ammonia was a pretty common refrigerant at one time. I ran a refer ship that had ammonia refrigeration and it was very efficient, but extremely dangerous.
Seems at least according to the Danfloss web site (was reading on my phone the other day so I don't have a link) it is still used in industrial refrigeration today. They were even touting it as more environmentally friendly than any of the new freon replacements.