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ACRC Technical Report 155PDF


Title:Fault Detection and Diagnosis in Air Conditioners and Refrigerators
Author(s):Noonan, A.M.; Miller, N.R.; Bullard, C.W.
Subject(s):fault detection
Abstract:A fault detection and diagnosis (FDD) method was used to detect and diagnose faults on both a refrigerator and an air conditioner during normal cycling operation. The objective of the method is to identify a set of sensors that can detect faults reliably before they severely hinder system performance. Unlike other methods, this one depends on the accuracy of a number of small, on-line linear models, each of which is valid over a limited range of operating conditions. To detect N faults, N sensors are needed. Using M>N sensors can further reduce the risk of false positives. For both the refrigerator and air conditioner systems, about 1000 combinations of candidate sensor locations were examined. Through inspection of matrix condition numbers and each sensor's contribution to fault detection calculation, the highest quality sets of sensors were identified. The issue of detecting simultaneous multiple faults was also addressed, with varying success. Fault detection was verified using both model simulations and experimental data. The results were similar, although in practice only one of the two would probably be used. Both load-type faults (such as door gasket leaks) and system faults were simulated on the refrigerator. It was found that system faults were generally more easily detectable than load faults. Refrigerator experiments were performed on a typical household refrigerator because it was readily available in a laboratory, but the results of this project may be more immediately useful on larger commercial, industrial or transport refrigeration systems. Air conditioner experiments were performed on a 3-ton split system. Again, the economic benefits of this type of fault detection scheme may also be more feasible for larger field-assembled systems.
Issue Date:1999-08
Publisher:Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Air Conditioning and Refrigeration Center TR-155
Genre:Technical Report
Sponsor:Air Conditioning and Refrigeration Project 87
Date Available in IDEALS:2009-05-26
Identifier in Online Catalog:4259478

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