Patent ID: 7681407

Claim:
A flash gas detection device for a vapour-compression refrigeration or heat pump system comprising a compressor, a condenser, an expansion device, and an evaporator interconnected by conduits providing a flow path for a refrigerant, wherein the device comprises: means for determining a first rate of heat flow of a heat exchange fluid flow across a heat exchanger of the system and a second rate of heat flow of the refrigerant across the heat exchanger, and using the rates of heat flow for establishing an energy balance from which a residual for monitoring the refrigerant mass flow is derived; and evaluation means for evaluating the refrigerant mass flow, and providing an output signal indicating the presence or absence of flash gas, based on the residual, wherein the means for determining the second rate of heat flow uses inputs from means for sensing absolute refrigerant pressure before and after the expansion device, means for establishing an opening passage or opening period of the expansion device, and means for storing a value representing a flow characteristic of the expansion device, without requiring measurement of refrigerant temperature at the expansion device entry and exit.