What Could Possibly Go Wrong? A Laboratory Investigation of In-Field and Onboard FDD on a 5 Ton RTU

Transcription

1 What Could Possibly Go Wrong? A Laboratory Investigation of In-Field and Onboard FDD on a 5 Ton RTU 2014 ET Summit New Packaged HVAC System Sensors, Logic and Communications Tons of Potential October 21, 2014 Sean Gouw, PE Southern California Edison Technology Test Centers

2 Today s Discussion Items Objective: discuss SCE project: fault impacts and explore FDD 1. Policy Drivers & Problem Definition 2. Project Description & Long-term Activities 3. Results 4. Conclusions & What s Next? 5. Questions? 1

3 1. Policy Drivers & Problem Definition 2

4 Policy Drivers AB32: GHG Goals By GHG reduced 25% below 1990 levels CLTEESP, Big Bold Energy Efficiency Strategies Commercial New Construction ZNE by 2030 HVAC Market Transformation Goal 4: New HVAC Technologies & System Diagnostics 3

5 California HVAC Facts CA commercial non-coincident peak demand 15 GW and annual energy use 67 billion kwh Cooling = 4GW, 10 billion kwh (15%) Single zone packaged and split systems comprise 70% of CA commercial HVAC 81% of single zone packaged and split <65,000 Btu/h California Commercial End-Use Survey Peak demand values are not coincident across multiple end uses and do not sum up to commercial segment total 3. California Commercial Saturation Survey (CSS) Report FINAL. 4

6 Problem Definition At least 10% of commercial HVAC energy due to excessive run time, poorly maintained equipment, and controls problems 1 More understanding is needed regarding the impacts of overlooked maintenance 1. Advanced Automated HVAC Fault Detection and Diagnostics Commercialization Program. 5

7 What could possibly go wrong? 6

8 The RTU Test Unit Type Nameplate Charge Refrigerant Expansion Device Nominal Cooling AHRI-Rated Cooling Efficiency Nominal Evaporator Airflow RTU, Fixed Capacity 20 lbs R-410a TXV 5 ton 57,500 Btu/h EER, 15.2 SEER 1750 SCFM 7

9 A lot, actually 8 Air Conditioner / Heat Pump - Cooling Mode Air Conditioner / Heat Pump - Cooling Mode Air-side Circuit Air-side Circuit Indoor Section Outdoor Section Economizer Faults Return/Supply openings Filter UV Lamp Evaporator Indoor Section Fan Combustion chamber Burner Flue Faults Inlet/Outlet Condenser Condenser Fan Outdoor sensor Return air sensor Mixed air/discharge sensor Economizer controller Outside air damper Outside air damper motor Actuator / Linkage Reduced heat transfer effectiveness (nonairflow) Variable Speed Drive Motor contactor Bearing Fan blades Fan Housing Fan blades Fan Housing Fouling Obstruction Damaged Surfaces/Fins Fouling Damaged Surfaces/Fins Improper Operation Pitting/other damage Wear Wear Improper Tension Wear Improper Alignment Dirty/damaged Dirty/damaged Wear Poor alignment Poor bearing seating Fouling Obstruction Damaged Surfaces/Fins Fouling Damaged Surfaces/Fins Improper Operation Pitting/other damage Wear Wear Improper Tension Wear Improper Alignment Dirty/damaged Dirty/damaged Wear Poor alignment Poor bearing seating Bad condition/setting/operation Bad condition / Changeover controller setting / operation High limit setpoint Low limit setpoint Range/action setup incorrect Minimum OA Obstruction / stuck damper Dirty/no lubrication/damaged Damaged components No lubrication Bad setting Broken Wear Mis-aligned Loose No lubricant Copyright 2014, Not economizing Southern when it should California Edison Symptoms Low Airflow Deterioration Leaks Moisture problems Condensation Combustion products Deterioration Leaks Moisture problems Condensation Combustion products Deterioration Leaks Moisture problems Condensation Combustion products Low Airflow Sheave Fan drive Obstruction Dirty Obstruction Improper fit Compromised housing seal integrity Belt Sheave Fan drive Belt Dirty/damaged Obstruction Bad condition/setting/operation Bad condition/setting/operation Damaged Excess outdoor air Low ventilation Disabled Air Conditioner / Heat Pump - Cooling Mode Air Conditioner / Heat Pump - Cooling Mode Air-side Circuit Reduced heat transfer effectiveness (nonairflow) Variable Speed Drive Motor contactor Bearing Refrigerantside Circuit Control system Misc. Cabinet Ducts Refrigerant charge Refrigerant Circuit Lines Compressor Expansion Device Filter/Drier Thermostat Sensors Control Box Low ambient head pressure control Other devices? Symptom Steam system traps, pumps, and controls P-trap Other field-servicable bearings Condensate drain pan Condensate drain line Exposed ductwork External piping Vapor barrier Insulation Other areas Symptoms Faults Panels Fasteners Gaskets Curbs Symptoms High Charge Low Charge Liquid Line Suction Line Discharge Line Evaporator circuit Condenser circuit Valves Bearings Oil Variable Speed Drive Motor contactor Symptoms Capillary Tube Thermostatic Expansion Valve (TXV) Electronic Expansion Valve (EEV) Faults Missing Filter Panel Damaged Missing Fan Access Panel Damaged Missing Compressor Panel Damaged Missing Damaged Damaged Damaged High pressure drop Improper install Obstruction / Restriction Air leaks High Charge High Charge - Compromised Blend Low Charge Low Charge - Compromised Blend Non-Condensables / Contaminants Bend / Obstruction Refrigerant leaks Bend / Obstruction Refrigerant leaks Bend / Obstruction Refrigerant leaks Refrigerant leaks Refrigerant leaks Valve Leakage Seized Bearing Low Oil level/pressure Improper Operation Pitting/other damage Short cycling Obstruction Obstruction Sensing Bulb Fault Improper Adjustment Obstruction Sensor Fault Improper Adjustment Obstruction Incorrect scheduling Improper Programming/Adjustment Improper Location Communication Failure Failure/fault Drift Dirt/debris Loose terminations Damaged components Software/algorithm modifications needed Improper operation Improper operation Dirty/broken Not primed Wear Biological growth Biological growth Obstruction Missing insulation Missing insulation compromised integrity Biological growth Moisture carryover beyond drain pan from evaporator condensate Biological growth Efficiency does not meet unit rating Capacity does not meet unit rating

10 Focusing on Important Common Faults Selected with industry expert guidance 1. Low Refrigerant Charge 2. High Refrigerant Charge 3. Liquid Line Restrictions 4. Non-Condensables 5. Evaporator Airflow Reduction 6. Condenser Airflow Reduction 7. Economizer communication/mechanical faults 9

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13 FDD Technologies FDD technologies can help enhance HVAC maintenance practices with consistent, reliable, & increased understanding of the HVAC system In-field tools, onboard systems Troubleshooting existing faults & early prevention Sustained, optimized HVAC performance Improved human comfort/productivity & equipment life Improved efficiency & reduced impacts to GHG emissions Reduced impacts to economic resources of customers 12

14 FDD Barriers and Challenges Need for Understanding FDD Technologies Performance Little/no consistency across technologies No industry accepted methods to make FDD value more transparent/quantifiable Functions, capabilities, accuracy, reliability High Technology Cost & Unknown End-User Interaction How does it enhance maintenance? Technology must meet somewhere with a well trained/experienced technician What faults exist / likely to occur? Correctly diagnosed? What corrective actions taken, if any? 13

15 2. Project Description & Long-Term Activities Establish Technical Advisory Group (TAG) Develop FDD Lab Test Method Quantify Impacts of Common Faults Explore FDD Accuracy 5-Ton RTU Onboard & In-Field FDD Long-term Activities Assess new technologies under SCE Emerging Technologies program & enhance EE measures Engage/inform industry (ASHRAE, SPC207P, WHPA ) Strengthen T-24 Energy Code, contribute to federal voluntary/mandatory standards 14

16 Lab Testing: Strategy & Monitoring Plan 45 Steady-state tests conducted at 3 rd party AHRIcertified lab & SCE s TTC Performance metrics: gross cooling, total power, & efficiency 65 Measurement points recorded every 20 seconds 2 Economizer tests non-ss-test-style 15

17 3. Results 16

18 FDD Test Units Three FDD test units: two in-field, one onboard Wide library of alarms/diagnostic messages available across the three FDD, not all applicable to fault test scope FDD Test Unit A = 6/46 alarms pertinent to test scope FDD Test Unit B = 12/49 alarms pertinent to test scope FDD Test Unit C = 16/36 alarms pertinent to test scope FDD Test FDD Test FDD Test Fault Unit A Unit B Unit C Low Charge High Charge Liquid Line Restrictions Non-Condensables X X Evaporator Airflow Reduction Condenser Airflow Reduction Economizer Mechanical/Communications Faults X X 17

19 FDD Potential Responses 1 1. No Response the FDD protocol cannot be applied for a given input scenario, or does not give an output because of excessive uncertainty. 2. Correct the operating condition, whether faulted or unfaulted, is correctly identified 3. False Alarm no significant fault is present, but the protocol indicates the presence of a fault. 4. Misdiagnosis a significant fault is present, but the protocol misdiagnoses what type of fault it is. 5. Missed Detection a significant fault is present, but the protocol indicates that no fault is present. 1. A Method For Evaluating Diagnostic Protocols For Packaged Air Conditioning Equipment. 18

20 Diagnostics Analysis: Choosing a Fault Threshold Acceptable fault thresholds will vary, for our purposes: Fault recognized if Air-side efficiency degradation >10% Fault recognized if refrigerant overcharge >5% Overcharge impact on steady-state performance not significant, but reliability concerns due to low superheat and slugging of the compressor 19

21 Diagnostics Analysis Summary 45 Steady-State Test Scenarios Diagnostics FIR = -10% EER (or 5% overcharge) FDD Unit FDD Test Unit A FDD Test Unit B FDD Test Unit C Response # of Scenarios Correct Response? 24 Mis-diagnosis? 5 Correct Response? 23 Mis-diagnosis? 10 Correct Response? 29 Mis-diagnosis? 16 Multiple responses counted per scenario Single fault scenario where correct AND misdiagnosis responses occur Multiple fault scenario where one fault is diagnosed Three FDD technologies similar in performance Setting the right metrics & expectations 20

22 4. Conclusions Low charge and condenser airflow reduction demonstrated highest single-fault potential to reduce steady-state performance & efficiency, high charge isn t as pronounced, but yields reliability concerns Three FDD technologies similar in correct/misdiagnoses responses Approach for exploring FDD should continue to be improved to help make FDD value more transparent Field, lab, and simulation efforts should continue, and be cohesively leveraged to further the understanding of FDD and HVAC faults More info is needed regarding prevalence/incidence of HVAC faults and measured impacts in the field A consistent lab test method should be established What s Next? Validated simulation methods should be used to explore the overwhelming amount of possible scenarios 21

23 5. Questions? Sean Gouw, PE 22

24 Appendix 23

25 The Technical Advisory Group (TAG) Western HVAC Performance Alliance Verified WCEC NBI PECI NIST Carrier Purdue University of Nebraska PNNL Field Diagnostics Services, Inc. PG&E Sempra Taylor Engineering Climacheck SCE 24

26 What about multiple faults? 25

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