SENSING OF A VAPOR QUALITY

The invention relates to a method and device for providing a sensor signal (S) indicative of a vapor quality (X) of a medium flowing within a conduit (60). An electromagnetic wave emitter and receiver 50 is coupled to an electromagnetic wave guide 48 arranged within the conduit 60. A wave reflector 52 is arranged to reflect the electromagnetic wave from the emitter to be received by the receiver. Timing means measure a travel time T of an electro-magnetic wave along the wave guide 48. Processing means determine a sensor signal S based on the measured travel time T and a known distance L of the reflector 52 from the emitter and receiver 50 along the wave guide 48.The invention further relates to a cooling system 10, 110 and an operating method therefor. The cooling system 10, 110 includes at least one evaporator 32 for evaporating an ammonia refrigerant, at least one compressor 12 arranged to compress the evaporated refrigerant, and at least one condenser 18 for condensing the compressed refrigerant. A sensor signal S indicative of a vapor quality X of the refrigerant in a conduit 38a between at least a portion of the evaporator 32 and the compressor 12 is obtained from the described sensor and method.