What is meant by 'flash gas' in refrigeration?

Flash gas refers to the phenomenon that occurs when a liquid refrigerant enters a low-pressure area, such as the expansion valve or evaporator in a refrigeration system. When the refrigerant experiences a reduction in pressure, it can instantaneously boil or vaporize, resulting in the formation of gas. This process is critical to the refrigeration cycle, as it contributes to the cooling effect by absorbing heat from the environment.

In refrigeration systems, the proper functioning of the expansion valve ensures that the liquid refrigerant expands and changes phase into a gas, effectively leading to the desired cooling effect. Understanding this concept helps technicians identify how to optimize system performance and troubleshoot potential issues related to insufficient cooling or improper refrigerant flow.