Fault Detection and Diagnostics for Rooftop Air Conditioners

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Figure 2-10 Decoupling refrigerant leakage faults using ∆ Tsh
− sc......................................61
Figure 2-12 Timeline of the fault simulation in minutes. ..................................................63
Figure 2-13 Outputs of the FDD demonstration after introduction of low refrigerant
charge fault.................................................................................................................67
Figure 2-14 Outputs of the FDD demonstration after introduction of condenser fouling
fault ............................................................................................................................68
Figure 2-15 Outputs of the FDD demonstration after introduction of liquid line restriction
fault ............................................................................................................................69
Figure 2-16 Outputs of the FDD demonstration after introduction of compressor leakage
fault ............................................................................................................................70
Figure 2-17 Outputs of the FDD demonstration after removal of condenser fouling fault
....................................................................................................................................71
Figure 2-18 Outputs of the FDD demonstration after removal of liquid line restriction
fault ............................................................................................................................72
Figure 2-19 Outputs of the FDD demonstration after removal of compressor leakage fault
....................................................................................................................................73
Figure 2-20 Outputs of the FDD demonstration after removal of low refrigerant low
charge fault.................................................................................................................74
Figure 2-21 Histogram bar plot of the normalized fault indicator for liquid line restriction
....................................................................................................................................76
Figure 2-22 Histogram bar plot of the normalized fault indicator for refrigerant low
charge .........................................................................................................................76
Figure 2-23 Histogram bar plot of the normalized fault indicator for condenser fouling .77
Figure 2-24 Histogram bar plot of the normalized fault indicator for compressor valve
leakage .......................................................................................................................78
Figure 2-25 Histogram bar plot of the normalized fault indicator for cooling capacity
degradation.................................................................................................................79
Figure 2-26 Histogram bar plot of the return air temperature ...........................................79
Figure 2-27 Histogram bar plot of the continuous running time between off-cycles of the
RTU............................................................................................................................80
Figure 2-28 Histogram bar plot of the normalized fault indicator for EER degradation...81
Figure 2-29 System power consumption reduction ...........................................................81
Figure A1-1 The CA value of an ALCO EXV of manufacturer rating conditions............95
Figure A1-2 The CA value of a SPORLAN TXV of manufacturer rating conditions ......95
Figure A1-3 P-T saturation curve for R22.........................................................................96
Figure A1-4 Three types of valve geometry......................................................................97
Figure A1-5 Geometric model of type I and II valve ........................................................98
Figure A1-6 Throat-area curves of different valve types...................................................98
Figure A1-7 Geometric model of valve type III................................................................99
Figure A1-8 Valve position curve....................................................................................100
Figure A1-10 The C d
A value of the 5-ton Trane RTU TXV as a function of superheat
..................................................................................................................................106
Figure A1-11 Comparison of TXV modeling error.........................................................107
Figure A1-12 Illustration of the three parameter estimation methods .............................108
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