Package DX Units: Performance Optimization & Field Tests

1 Package DX Units: Performance Optimization & Field TestsMichael West, PhD, PEAdvantek Consulting Engineering, POWERED :: CLIENT DRIVENU nitary equipment is ubiquitous. 60% of US commercial space is cooled with RTUs (DOE) 54% of commercial building cooling primary energy consumption (EIA) Total annual installations over 300,000 units Estimated million legacy units operating at low efficiency levels100,000 units at DoD facilities / 20,000 buildings100,000 units at USPS facilities / 30,000 buildings500,000 units at 65,000 big box retail storesRTU Rooftop packaged air-conditioner UnitDOE Department of EnergyEIA Energy Information AdministrationUSPS United States Postal ServiceBackgroundROOFTOPPORTABLE PAD MOUNTSPLIT SYSTEM How much cooling you get for the electricity it uses Btuh per Watt (MBH per kW) EER Energy Efficiency RatioFull Load @95F Ambient IEER Integrated Energy Efficiency RatioWeighted Full Load & Part Load @95, , 68, and 65F SEER Seasonal EER Part Load @82F Ambient x Performance Load Factor IPLV Integrated Part-load ValueLegacy rating (no longer standard)

2 Performance RatingsANSI/AHRI Standard 340/360-2007 Drivers1. Energy saving goals continue to rise IEER -Integrated Energy Efficiency Ratio to , EER Energy Efficiency Ratio to Upcoming DOE 10% and 30% increases in efficiency minimums Single-zone VAV and DDC requirements of Energy Standard and Green Standard Dehumidification needs are increasing Reduced sensible loads means lower SHR-Lower lighting Watts / sqft-Higher insulation R-values-Heat reflective / low-e glass-often addressed with energy intensive reheat Part-load requirements of IAQ Standard (< 65%rh)4often solved with energy intensive reheatAmbient AirEvaporator CoilCondenser CoilCompressorTXVB asic DX CycleSupply AirRevises the traditional refrigeration cycle at a fundamental of evaporator refrigerant / two-phase heat suction density improves compressor volumetric sensible heat ratio optimizes airside Performance . REFRIGERANT CIRCUITCOIL HEAT TRANSFERTXV Thermostatic Expansion ValveModified DX CycleSignificance of DX ModificationReleases constraints on operating , temperatures, and refrigerant can be Constant-Temperature (VVCT) latent capacity as SHR (VSHR)

3 Controls all operating parameters Target is maximum EER while precisely meeting sensible and latent loads Continuous Performance tuning Supply Blower Speed Condenser Fan Speed Refrigerant Charge Supply Air Temperature Coil Temperature Economizer Damper Continuous web reporting EER, IEER, Tons Capacity Faults, such as low refrigerant or fouled coil Diagnostics detects issues before problematicData ConnectivityRTUC ontrollerGUIAny Web DeviceTablet, Smart Phone, LaptopCloud ServersphpWebSocketLANVPN or commercial WANI nternetDatabaseSupercharged Package UnitOptimizing Control PackageLiquid-Suction Heat Exchanger AccumulatorBypass DamperVariable FrequencyBlower DriveAdjustableThermostaticExpansionValv eVFD Condenser FanInstallationSite 1: Retail StoreBeaufort, South Carolina2627 cooling degree-daysClimate zone 3A Warm-HumidSouth CarolinaField Tests20-ton dual-circuitR-22 Package DX unit Gas heatManufactured 2/2003 Found in poor conditionSouth CarolinaField TestsFresh air intakeGas heating sectionCompressorsCaliforniaSite 2: Classroom BuildingMojave, CaliforniaElevation 2500 feetField TestsClimate zone 3B Hot-Dry 3225 cooling degree-days2597 heating degree-daysField Tests12 -ton dual-circuitR410a Package DX unitHeat PumpInstalled 2010 CaliforniaSite 3.

4 Electronics Development LaboratoryCape Canaveral, Florida3633 cooling degree-days, Climate zone 2A Hot-HumidFloridaField Tests8 -ton dual-circuitR410a Package DX unit9 kW-heat Installed 1/2012 Field TestsFloridaPerformance measurement data available live via web Analysis45 Sensors on each RTU Compressor Amps (2) Fan and Blower Power Total unit Power Refrigerant Pressures (4) Refrigerant Temperatures (12) Refrigerant Flows (2) Air Temperaturesat thermostat, return, outdoor, coil, entering & leaving coil, unit discharge Air Humiditycoil entering, unit discharge, at thermostat, outdoor Space and Ambient CO2level Control point statusField Test ResultsDamper Position Control Signal vs RHTest Site: Beaufort, SC02040608010040455055606570 Space Relative Humidity [%rh]% Damper OpenOpeningClosingCondenser Fan Speed Signal vs OATTest Site: Beaufort, SC0204060801005060708090100 Outside Air Temperature [F]% SpeedStage 2 Stage 1 The optimizing controller tuned the RTU s operation according to varying conditions as is control of damper position and condenser fan speed with change in humidity and Test ResultsBeaufort SC Field Test Preliminary Result 15% IEER increase from to 15% operational EER increase Elimination of startup efficiency loss Reduced compressor cycling 27% less energy kWh/CDD consumedField Test ResultsMojave CA Field Test Preliminary Result 37% IEER increase from to 31% operational EER increase Elimination of startup efficiency loss Reduced variation with temperature 40% less energy kWh/CDD consumedField Test ResultsCape Canaveral FL Preliminary Result 22% IEER increase from to 23% operational EER increase Elimination of startup efficiency loss Reduced compressor cycling 37% less energy kWh/CDD consumed Not counting reheat energy savings Space humidity between 45 ~ 50%rhResults SummaryBeaufort, SCMojave.

5 CACape Canaveral, FLConclusionField Test Results Web connection from anywhere Fault detection & diagnostics 15 to 37% operational IEER increase Elimination of startup efficiency losses 27% to 40% less energy kWh/CDD Improved dehumidification Cooler compressor operation Reduced compressor cycling