Patent ID: 9587866
Date: 2017-03-07
CPC Classifications: F25B,G01F,G01N

Claim:
1. A refrigeration system for ammonia comprising at least one compressor which delivers compressed ammonia gas to at least one condenser, which condenser delivers liquid ammonia to at least one flow restriction, from which flow restriction, low pressure ammonia flows to at least one evaporator having a liquid ammonia inlet, from which evaporated ammonia flows back to the compressor, an expansion valve which controls the liquid ammonia inlet, which system comprises at least one sensor for detecting liquid ammonia in suction gas, the sensor being formed as at least one capacitive sensor that is connected to a control unit, which control unit controls operation of the refrigeration system, which capacitance sensor comprises at least a first and a second sensor electrode, which capacitance sensor at least measures the capacitance between at least the first and at least the second electrodes, where at least one of the sensor electrodes is formed as a tube which measures the liquid/gas content of the suction ammonia gas flowing from the evaporator towards the compressor, which control system, based on measurements obtained by the at least one capacitive sensor, is adapted to calculate at least one dataset for controlling the refrigeration system, whereby the system is adapted for controlling an expansion valve so as to reduce overheating of the evaporator based on the liquid/gas content of the suction ammonia gas measured.