High vapor density: this parameter is of key importance,
especially for fluids showing a very low condensing pressure (e.g. silicon oils).
A low density leads to a higher volume flow rate: the sizes of the heat exchangers must be increased to limit the pressure drops. This has a non-negligible impact on
the cost of the system. It should however be noted that larger volume flow rates can allow a simpler design in the case of turboexpanders, for which size is not a crucial parameter.