chiller

Word of the Month: Refrigerant

What is Refrigerant?

Refrigerant is a chemical compound which easily transforms from liquid to gas state. It is an essential component of cooling, and is used in all air conditioners, coolers, and refrigerators.  In terms of its chemical composition, there are a few different types:

  • CFC’s: Chlorofluorocarbons, such as R12, which are no longer in production due to detrimental effects on the environment from greenhouse gases
  • HCFC’s: Hydrochlorofluorocarbons, such as R22, which create some emissions
  • HFC’s: Hydrofluorocarbons, such as R134, & R410A, which is the safest for the environment, the most efficient, and provides the best air quality & comfort 

When pressure within an air conditioning system is manipulated, the refrigerant changes states, which is what contributes to the cooling process. 

How Does it Work?

Refrigerant is often located inside copper coils within an air conditioner, and absorbs heat in order to cool circulating air. Pressure is used to manipulate the state of the refrigerant, which is what contributes to the cooling process. Think of the equation PV = nRT; when pressure (P) goes up or down, there is also an effect on the other side of the equation (temperature T). 

The cooling process involving refrigerant can be summarized in about 3 steps:

  1. Compression: The refrigerant is compressed as a low pressure gas, and heats up. This is why the outside of an air conditioner is often hotter than surrounding air!
  2. Condensation: Fans blow across pipes, cooling the hot gas. The refrigerant turns back into a liquid, and the temperature is lower.
  3. Evaporation: The low pressure liquid refrigerant is heated up again to be evaporated, and the fan blows over the gas, which absorbs heat. The chilled air, which has lost heat, is then blown into the building, and the cycle continues.

This process, which occurs in your home's HVAC air conditioning system, also takes place in the CHCP plant within the chillers. 

Why Do We Use It?

In the campus cooling system, refrigerant is used in the chillers located in the CHCP Plant. Like an air conditioner, refrigerant is moved through heat exchangers, and the pressure inside is manipulated so that the refrigerant changes from gas to liquid, and from liquid to gas.

Inside the chiller, the vaporized refrigerant is compressed inside massive compressors so that it can be turned back into liquid refrigerant inside a condenser, where the heat is expelled through a condenser water circuit that carries it out to a cooling tower.