Patent ID: 7069734

Claim:
A method for detecting surge in a refrigeration system, said refrigeration system including a centrifugal compressor having an impeller and a compressor entrance, an evaporator that receives a fluid refrigerant, a suction line that flows said refrigerant from said evaporator to said compressor entrance, said evaporator including a heat-exchange coil supplied with a liquid through a supply line entering said evaporator, said liquid disposed in a heat-exchange relationship with said refrigerant within said evaporator, the method comprising automatically and periodically performing the steps of: measuring a fluid temperature of said liquid proximate said supply line entering said evaporator; measuring a refrigerant temperature of said refrigerant proximate said compressor entrance; using said fluid temperature and said refrigerant temperature to detect surge in said refrigeration system by computing a value indicative of a temperature difference between said fluid temperature and said refrigerant temperature; and comparing said value to a set point temperature.