Cryogenic chilling in the PETROGAS Model TE System utilizes a TURBO EXPANDER that replaces the Joule-Thompson expansion valve in a conventional refrigeration system. The expansion valve is adiabatic as well as a turbine, and taking the work out of the expansion makes it isentropic.

Isentropic expansion allows for a lower temperature of the expanded refrigerant at the same pressure reduction. The more efficient turbo expansion cycle allows the use of aliphatic hydrocarbons, such as ethane, as a refrigerant.