Flash-gas (refrigeration)

[3] This is normally perceived as an unwanted condition caused by dissociation between the volume of the system, and the pressures and temperatures that allow the refrigerant to be liquid.

These create low pressure loci that may cause the fluid to begin changing its phase, especially if the pipeline is exposed to heat, through, for example, gaps in insulation.

[4] If there is inadequate subcooling, the refrigerant remains in thermodynamic conditions close to saturation, promoting flash-gas formation.

On the other hand, lack of refrigerant can sometimes also produce the opposite effect: an overall increase on the subcooling (and superheating) which will depend on the size and design of the system and its piping.

This is due to the fact that the refrigerant may use part of the heat obtained from lowering its temperature, to finish vaporizing itself to be able to occupy the volume of the pipes at those pressures.

Efforts to prevent flash-gas in the liquid line include a cautious design of the cooling system and its piping, but also the incorporation of gear that might help solve this type of difficulty.

The inclusion of a refrigerant receiver is a common, cheap and simple way of decreasing the gas ratio in the liquid line.

A column of refrigerant creating weight pressure in the liquid line can be a solution for flash-gas, but may have incidence in the expansion and evaporation.

First, the expansion valve usually doesn't work properly if injecting a gas-liquid mixture such as refrigerant with flash-gas presence.

Both, lack of evaporation, and untimed transformations of energy from work to heat: increase the pressures and temperatures along the pipes; decrease the thermodynamic reversibility of the process, and raise the overall magnitude of entropy produced throughout the whole cycle.

Besides, these kinds of efficiency losses not only underutilize gear, but may end up lowering the operative life of the main components, especially the expansion valve and the gas compressor.