Refrigerants, often referred to as heat carriers or working fluids, are an essential part of every system designed to control temperature with vapour compression technology. Refrigerants are the blood circulating in every system relying on this technology. Refrigerants can be broadly divided into two macro categories: synthetic ones, e.g., man-made chemical products that are not found in the environment, and natural ones, i.e., chemical substances that are naturally occurring and can be found in great abundance in the environment.