Fault Detection and Diagnostics for Rooftop Air Conditioners

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70 simultaneous faults: refrigerant low charge with the fault severity over 1.0, condenser fouling with the fault severity around 0.5 and liquid line restriction fault with the severity around 0.35. Since refrigerant charge fault is a system-level fault whose indicator was impacted by other faults, the refrigerant low charge indicator value increased after the liquid line restriction fault was introduced. Since the COP was degraded 21% at this moment (see SPSDW and FDDRW), FDDRW recommended that: the system requires more refrigerant, the condenser requires cleaning and the filter/drier requires replacement. Although every individual fault was not severe enough to cause more than a 20% performance degradation, the combination of three simultaneous faults aggravated overall system performance degradations. Figure 4-17 Outputs of the FDD demonstration after introduction of liquid line restriction fault
71 Figure 4-18 shows one frame after the compressor leakage fault was introduced by opening the discharge bypass valve until about 15% of refrigerant mass flow rate was reduced (step 4 of section 4.2.3.1). FDDW indicates that there existed four simultaneous faults: refrigerant low charge with the fault severity over 0.70, condenser fouling with the fault severity around 0.5, liquid line restriction fault with the fault severity around 0.35 and compressor leakage fault with the fault severity around 0.5. Since the COP was degraded 24% at this moment (see SPSDW and FDDRW), FDDRW recommended that: the system requires more refrigerant, the condenser requires cleaning, the filter/drier requires replacement and the compressor requires service. Figure 4-18 Outputs of the FDD demonstration after introduction of compressor leakage fault
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CALIFORNIA ENERGY COMMISSION Final
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Acknowledgements Jim Braun and Haor
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Abstract Project 2.1, Fault Detecti
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TABLE OF CONTENTS LIST OF TABLES LI
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LIST OF FIGURES Page 1 - Field Test
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The report “Description of Labora
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mounted heat pumps for heating and
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The retail stores are in Southern C
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Figure 1 - Field Test Sites Data Co
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Gibson School (Cont’d) Woodland S
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Table 1 - Data List for Modular Sch
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BUILDING TYPE: Modular School Rooms
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HEATING / AIR CONDITIONING EQUIPMEN
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Sacramento Area McDonalds PlayPlace
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Bradshaw Road (Sacramento Area) McD
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TEST INSTRUMENTATION: Tables 2 and
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Table 2 - Data List for Inland Rest
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Castro Valley (San Francisco Bay Ar
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Castro Valley McDonalds PlayPlace P
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more or less custom design, publish
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BUILDING TYPE: Retail Store ADDRESS
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TEST INSTRUMENTATION: Similar test
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• Temperature and humidity levels
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November 2001 - December/January 20
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Table of Contents 1. Introduction..
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1. Introduction All the thermodynam
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Table 1.1 Comparisons of Three Mode
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solution procedure involves the non
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independent of the moisture content
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function, f ( X , y) , if it can be
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Figure 2.1 Neural-Network Implement
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prototype was developed by using th
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3. Comparison of black-box modeling
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which is more accurate than the exp
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Similar to GRNN, RBF has very good
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Table 3.2 RMS error (Polynomial,GRN
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Table 3.4 Contrast of Black-box mod
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Polynomial plus GRNN Training Desir
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interpolation(poly+GRNN) extrapolat
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used to build the steady-state mode
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α , ρ, τ I t t s h o A t a Figur
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Temperature (F) 82 79 76 73 Condens
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0.050 0.045 Pressure = 101.3 [kPa]
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T T − T − T W = W −W −W m =
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Figure 4.8 Output of three steady-s
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will be calculated to represent the
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180 175 RMS error = 0.3984 (F) Pred
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180 175 RMS error =1.1472 (F) Predi
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51 50 RMS error=0.3860 (F) Predicte
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4.4 California field site results S
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105 100 RMS error =0.5982 (F) Predi
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Since air conditioners always cycle
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6. Conclusions and future work So f
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Lee, W., House, J.M. and Shin, D.R.
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Table of Contents 1 Introduction...
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AHU α β 2 d i EER ∆ ∆ η v T
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$ !! !! )
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Paper statistics in HVAC FDD Number
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011>" - , ?" 8?"
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+ : 6336" ,
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+ :: !!- :: !!
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6 24 122 7) 6 3++, ) . !! /011
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)
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336 F / s $ S
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N $ V v1
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Figure 3-4 2-dimensional residual d
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10 5 Normal and current operation p
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7 N Ω f N N Ω = Ω X ,
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0 + α 6 d χ ( )
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Normal operation region Residual-2
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Table 3-2 Refrigerant Leak at 20% l
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ratio dist = P F 1 P F 1 2 1 9.0
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$ , " - (
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)(( 0( 04 ) 6330" /
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Table 4-2 Polynomial plus GRNN mode
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4.2 m r,predict (kg/min) 4 3.8 3.6
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6 1)( ( ( 6 1)( ) , ( )
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- )
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? "J> *"J060 #"J083 *$"J670 #"J08<
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Table 4-17 Detected (normal, fault)
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c=1 c=10 c=20 1 0.8 Distance ratio
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$ /) $ 0111" .. !!
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Chen, Bin and Braun, J.E, 2000. Sim
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Ventilating, Air-Conditioning and R
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1.T amb 2.T ra 3.RH ra Plant Prepro
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F) $
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+: + $ 5
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.44(' * 5 09( ( 0( F N ( M , Σ)
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Load 20% 40% 60% 80% 100% 3 4 Fault
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Load 20% 40% 60% 80% 100% 3 4 Fault
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3 4 0 0 0 0 0.4173 0 0.0010 0 0.000
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.44(' $ () ) ) - $
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∆P Restrictio n Level=100%* ∆P
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2 TABLE OF CONTENTS TABLE OF CONTEN
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4 A1.2.3 Valve Position Expression
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6 Figure 2-10 Decoupling refrigeran
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8 LIST OF TABLES Table 1-1 Fault di
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10 N = Number of generated sample p
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12 with a fixed-orifice as the expa
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14 (residuals) should have a zero m
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16 expected distribution of the res
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18 operation. Another advantage is
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20 1.1.2.1 Original SRB Fault Diagn
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22 Corresponding to the SRB fault d
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24 integration of the probability d
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26 1. Simplifies fault detection fr
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28 Step i Do FDD on fault i . After
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30 ROOFTOP UNIT FAULTS COMPONENT-LE
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32 has two possible causes: refrige
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34 1.2.3 Decoupling of Component Fa
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36 1.2.3.2 Condenser-Related Faults
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38 mixture, χ ref is known as the
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40 Table 1-3 also lists the refrige
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42 Refrigerant Property T cond, pre
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44 as an independent feature only f
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46 evaporator air flow rate reducti
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48 5. 2 Pll ∆ deviates drasticall
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50 System-Level Faults RefUnder Ref
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52 1.2.5 Summary of Decoupling Sche
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54 noise, system disturbances and m
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56 compressor data. When there is a
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58 Figure 2-5 Decoupling evaporator
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60 Total Pressure Drop of Liquid- L
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62 Figure 2-11 Illustration of Demo
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64 bypass the compressor. At this t
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66 for T dis because there is no ov
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68 Figure 2-14 Outputs of the FDD d
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70 the system requires more refrige
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72 recommended that: the system req
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74 Figure 2-20 Outputs of the FDD d
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76 Figure 2-21 Histogram bar plot o
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82 2.3.2 Summarized Results for Oth
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84 3 CONCLUSIONS AND RECOMMENDATION
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86 Breuker, M.S. and Braun, J. E.,
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88 Lee, W., House, J.M. and Shin, D
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90 APPENDIX 1 PHYSICAL MODELS OF EX
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92 A1.1.2 Short-Tube Models Many re
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94 m& = CA ρ P up − P ) (A1-5) (
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96 The abrupt change of CA for the
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98 These equations can be combined
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100 H h T sh , max opening T sh , s
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102 A1.2.5 Parameter Estimation Met
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104 T (2 T sh, ratingopening , sh,m
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106 Harms’Result Harms plotted al
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108 Mass flow rate Local linearizat
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110 temperature on the RTD is unifo
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112 in cold water application, it i
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1 ACKNOWLEDGEMENTS The research tha
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3 2.2.3 Todd Harms’ Data ........
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5 LIST OF FIGURES Figure E-1. FDD d
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7 LIST OF TABLES Table E-1 FDD resu
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9 IA = Independence Assumption λ i
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11 EXECUTIVE SUMMARY Packaged air c
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13 current values of the fault indi
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15 Figure E-4 Histogram of the EER
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17 2. Operational cost savings, whi
Page 323 and 324: 19 Table E-5 Conservative Lifetime
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Page 327 and 328: 23 Paper statistics in HVAC FDD 35
Page 329 and 330: 25 on directional changes to identi
Page 331 and 332: 27 fault levels at different operat
Page 333 and 334: 29 was concluded that the method wa
Page 335 and 336: 31 However, several improvements ar
Page 337 and 338: 33 point sensor placement is genera
Page 339 and 340: 35 2 DATA SOURCES USED FOR EVALUATI
Page 341 and 342: 37 The fives types of faults are re
Page 343 and 344: 39 Occupation Type Climate Location
Page 345 and 346: 41 The SRB FDD method determines wh
Page 347 and 348: 43 The following sections describe
Page 349 and 350: 45 points rather than on a distribu
Page 351 and 352: 47 current operation point P 1, P F
Page 353 and 354: 49 4 A DECOUPLING-BASED FDD TECHNIQ
Page 355 and 356: 51 This approach overcomes the draw
Page 357 and 358: 53 ⎡ ∆T ⎢ ⎢ ∆T 2 ⎢ ∆
Page 359 and 360: 55 improving the compressor model p
Page 361 and 362: 57 Condenser Air Mass Flow Rate (lb
Page 363 and 364: 59 Evaporator Air Mass Flow Rate (l
Page 365 and 366: 61 Liquid-Line Pressure Drop (PSI)
Page 367 and 368: 63 4.2.2 Purdue Field Emulation Sit
Page 369 and 370: 65 1. Evacuated the system, and the
Page 371 and 372: 67 normal _ value − current _ val
Page 373: 69 Figure 4-16 shows one frame afte
Page 377 and 378: 73 valve position can be seen from
Page 379 and 380: Figure 4-22 Outputs of the FDD demo
Page 381 and 382: 77 Figure 4-23 Histogram bar plot o
Page 387 and 388: 83 4.2.3.2 Summarized Results for O
Page 389 and 390: 85 5 ECONOMIC ASSESSMENTS Since the
Page 391 and 392: 87 inspection savings would be $2,0
Page 393 and 394: 89 Q & Cap = W & × EER (5-2) The e
Page 395 and 396: 91 4. electricity costs ( C e ). Ut
Page 397 and 398: 93 Table 5-3 lists estimates of equ
Page 399 and 400: 95 5.4 Smart Service Schedule Savin
Page 401 and 402: 97 7. A 6-ton RTU having a cost of
Page 403 and 404: 99 Location North California South
Page 405 and 406: 101 5. Three case studies were inve
Page 407 and 408: 103 REFERENCES Aaron, D. A., and P.
Page 409 and 410: 105 Davis, Coby. 1993. Comparison o
Page 411: 107 Rossi, T.M., 1995. Detection, D
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Fault Detection and Diagnostics for Rooftop Air Conditioners

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