Diagnostic system for detecting faulty sensors in liquid chiller air conditioning system
First Claim
1. In an air conditioning system having a liquid chiller wherein refrigerant flows through an evaporator to chill liquid circulating through a heat exchange coil in the evaporator, a pressure sensor sensing the pressure of the refrigerant in the evaporator while a temperature sensor senses the temperature of the chilled liquid leaving the evaporator, a diagnostic system for detecting when either one of the sensors is faulty, comprising:
- means for developing, from the output of the pressure sensor, a refrigerant pressure signal representing the evaporator refrigerant pressure;
means for developing, from the output of the temperature sensor, a liquid temperature signal representing the leaving chilled liquid temperature;
computing means for determining, from the difference between the evaporator refrigerant temperature which is represented by said refrigerant pressure signal, and the leaving chilled liquid temperature which is represented by said liquid temperature signal, if the output of one or the sensors is in error, thereby indicating that the sensor is faulty;
and warning means, controlled by said computing means, for providing a warning message to operating personnel when a faulty sensor is detected.
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Accused Products
Abstract
When sensors are employed to monitor the evaporator refrigerant pressure and the leaving chilled liquid temperature in an air conditioning system of the type having a liquid chiller, the sensor outputs will normally have a prescribed relationship with respect to each other as long as the sensors are functioning properly and regardless of the operating condition of the air conditioning system. By effectively comparing the output of one sensor relative to that of the other sensor, a faulty condition of either sensor may be detected. This is achieved by calculating the equivalent evaporator temperature, from the evaporator refrigerant pressure, and subtracting the equivalent temperature from the leaving chilled liquid temperature to obtain a difference temperature which is then compared to a predetermined known temperature range representing normal functioning of the two sensors. When one of the sensors is defective the difference temperature will fall outside of the range. If that occurs, a warning message that a faulty sensor has been detected is displayed to operating personnel and the air conditioning system'"'"'s compressor is shut down as a safety precaution.
121 Citations
10 Claims
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1. In an air conditioning system having a liquid chiller wherein refrigerant flows through an evaporator to chill liquid circulating through a heat exchange coil in the evaporator, a pressure sensor sensing the pressure of the refrigerant in the evaporator while a temperature sensor senses the temperature of the chilled liquid leaving the evaporator, a diagnostic system for detecting when either one of the sensors is faulty, comprising:
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means for developing, from the output of the pressure sensor, a refrigerant pressure signal representing the evaporator refrigerant pressure; means for developing, from the output of the temperature sensor, a liquid temperature signal representing the leaving chilled liquid temperature; computing means for determining, from the difference between the evaporator refrigerant temperature which is represented by said refrigerant pressure signal, and the leaving chilled liquid temperature which is represented by said liquid temperature signal, if the output of one or the sensors is in error, thereby indicating that the sensor is faulty; and warning means, controlled by said computing means, for providing a warning message to operating personnel when a faulty sensor is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification