Fault Detection and Diagnostics for Rooftop Air Conditioners

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1.2.3.4 Evaporator Fouling Fault ...............................................................................45
1.2.3.5 Summary of Decoupling Component-Level Faults .......................................47
1.2.4 Decoupling System-Level Faults ..........................................................................49
1.2.5 Summary of Decoupling Schemes for Rooftop Unit System Faults ....................52
2 Case Studies ....................................................................................................................53
2.1 Case Study of Decoupling Rooftop Unit Faults ..........................................................53
2.1.1 Compressor Valve Leakage ..................................................................................53
2.1.2 Condenser Fouling Decoupling ............................................................................55
2.1.3 Evaporator Fouling Decoupling............................................................................56
2.1.4 Liquid-Line Restriction Decoupling .....................................................................58
2.1.5 Refrigerant Leakage Decoupling ..........................................................................60
2.2 Purdue Field Emulation Site’s Demonstration ............................................................61
2.2.1 Field Fault Simulation Window ............................................................................62
2.2.2 Fault Detection and Diagnosis Window ...............................................................64
2.2.3 System Performance & Safety Degradation Window ..........................................65
2.2.4 FDD Report Window ............................................................................................66
2.2.5 Output of the FDD Demonstration .......................................................................66
2.3 Results for California Field Sites.................................................................................75
2.3.1 Milpitas McDonalds Field Site .............................................................................75
2.3.2 Summarized Results for Other Sites .....................................................................82
3 Conclusions and Recommendations ...............................................................................84
Reference ...........................................................................................................................85
Appendix 1 Physical Models of Expansion Device...........................................................90
A1.1 Fixed-Area Expansion Device Models .................................................................90
A1.1.1 Orifice Models ...............................................................................................90
A1.1.2 Short-Tube Models ........................................................................................92
A1.1.2 Capillary-Tube Models ..................................................................................93
A1.2 Adjustable Throat-Area Expansion Valve Models ...............................................93
A2.2.1 Model Format Validation Using Manufacturers’Rating Data ......................94
A1.2.2 Derivation of Throat-Area A Expression......................................................97
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