What are refrigerants? Refrigerants are fluids that absorbs heat at low temperatures and rejects heat at higher temperatures. The principles of refrigerant allow for heat pumps and straight air conditioners to function properly; because of their pressure temperature relationship. This relationship allows for heat transfer. In the HVAC industry refrigerants are given a trade name known as “R” names. Examples of these names are R22, R134a, and R502. These names help to describe the different types of refrigerants. Refrigerants have various chemical make ups, along with different properties. Some refrigerants are only able to work in high pressures while others use low pressures to function properly.
Sometimes refrigerants consist of a two or more chemical compounds. These blends break down into two types: Zeotropes and Azeotropes. Zeotrope refrigerant mixes are mainly made of three different types of refrigerants. The characteristic that describes this type of refrigerant is that all three refrigerants keep their own properties; they act as 3 individual refrigerants. Azeotropes are mainly a blend of two refrigerants. The property that defines this type of refrigerant is it acts as a single refrigerant. This effect the boiling points of both types of refrigerants.
You must understand one of the most important fundamentals of refrigerants before expanding into how they work. This key principle is that refrigerants do not make things ‘cold’ they remove heat. This principle is preached in the HVAC industry. It is a common misunderstanding of homeowners and technicians. A pressure temperature relationship is a way of describing the specific temperature that relates directly with the pressure of a substance. This allows control of refrigerants boiling temperatures. Controlling a refrigerants boiling temperature allows for proper heat transfer. Heat transfer is when heat from one place is transferred to another place, this is also referred to as a refrigerant cycle. Generally we control heat transfer through air, water and refrigerants.
This type of heat transfer happens through conduction. Conduction is when heated molecules, with lots of movement, collide with slow moving molecules. The warmer molecules, fast moving, always move towards the cooler ones, or the slow moving molecules. Refrigerants are sold in disposable container that include a check valve. This limits the reuse of old refrigerants and prevents mixing refrigerants. Refrigerants are identified by a standard color code. The labels also contain information on which type of refrigerant is in the container along with any safety hazards there are.
There are several safety hazards when handling refrigerants. In order to help prevent damage to the ozone, technicians are required by law to become EPA certified. There are four (4) main types of certification; Type I, Type II, Type III, and UNIVERSAL. Type I includes small appliances such as refrigerators. Type II includes high pressure appliance with the exclusion of small appliances such as split-systems. Type III includes low pressure systems such as chillers. A Universal certification includes all three types of certifications. For more information on refrigerants, their properties, how they effect the environment, and becoming certified, consult your local supply house, manufacturers, or the escro institute.