Diagnostic system for detecting faulty sensors in liquid chiller air conditioning system

Patent · Tue Apr 28 04:00:00 EDT 1987

OSTI ID:6494411

Hansen, J C; Ginder, H B; Johnson, L A

This patent describes 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 senses 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 the refrigerant pressure signal, and the leaving chilled liquid temperature which is represented by the liquid temperature signal, if the output of one of the sensors is in error, thereby indicating that the sensor is faulty; and warning means, controlled by the computing means, for providing a warning message to operating personnel when a faulty sensor is detected.

• Assignee: NOV; NOV-87-059473; EDB-87-102761
• Patent Number(s): US 4660386
• OSTI ID: 6494411
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320106* -- Energy Conservation
Consumption
& Utilization-- Building Equipment-- (1987-)
AIR CONDITIONERS
ALARM SYSTEMS
COMPUTERIZED CONTROL SYSTEMS
CONTROL
CONTROL SYSTEMS
DIAGNOSTIC TECHNIQUES
EVAPORATORS
FAILURE MODE ANALYSIS
FLUIDS
FREEZERS
HEAT EXCHANGERS
MEASURING INSTRUMENTS
PERSONNEL
PRESSURE CONTROL
PRESSURE GAGES
REFRIGERANTS
SIGNALS
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
TEMPERATURE CONTROL
THERMOMETERS
WORKING FLUIDS