Apparatus and method for mass flow control of a working fluid

摘要

Apparatus for detecting working fluid state in a heat transfer system of the type having an evaporator and an expansion valve for controlling mass flow of the working fluid to the evaporator, comprises a first sensor disposed in the working fluid on the outlet side of the evaporator; the first sensor producing a first signal related to the working fluid state; a second sensor disposed in the working fluid on the inlet side of the evaporator; the second sensor producing a second signal related to a pressure dependent characteristic of the working fluid; and a control circuit for receiving the first and second signals and determining the working fluid state based on a ratio of the first and second signals.