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Variable Capacity Heat Pump RTF Sub-Committee

Variable Capacity Heat Pump RTF Sub-Committee. February 27, 2013 VRF Fan Energy Use and Part-Load Performance. Richard Raustad, Senior Research Engineer Florida Solar Energy Center rraustad@fsec.ucf.edu. Full-Load Cooling Performance. Controlled Region. Uncontrolled Region.

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Variable Capacity Heat Pump RTF Sub-Committee

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  1. Variable Capacity Heat Pump RTF Sub-Committee February 27, 2013 VRF Fan Energy Use and Part-Load Performance Richard Raustad, Senior Research Engineer Florida Solar Energy Center rraustad@fsec.ucf.edu

  2. Full-Load Cooling Performance Controlled Region Uncontrolled Region

  3. Full-Load Heating Performance

  4. Manufacturer Performance Correction(surrogate for part-load performance) 170 136 Capacity (kBtu/hr) 102 68 34 0 21 kW 28.1 kW 72 kBTU/hr 96 kBTU/hr

  5. EnergyPlus Cooling Model Inputs AirConditioner:VariableRefrigerantFlow, autosize, !- Rated Total Cooling Capacity {W} 3.802, !- Rated Cooling COP {W/W} -5, !- Minimum Outdoor Temperature in Cooling Mode {C} 43, !- Maximum Outdoor Temperature in Cooling Mode {C} VRFCoolCapFT, !- Cooling Capacity Ratio Modifier Function of Low Temperature Curve Name VRFCoolCapFTBoundary, !- Cooling Capacity Ratio Boundary Curve Name VRFCoolCapFTHi, !- Cooling Capacity Ratio Modifier Function of High Temperature Curve Name VRFCoolEIRFT, !- Cooling Energy Input Ratio Modifier Function of Low Temperature Curve Name VRFCoolEIRFTBoundary, !- Cooling Energy Input Ratio Boundary Curve Name VRFCoolEIRFTHi, !- Cooling Energy Input Ratio Modifier Function of High Temperature Curve Name CoolingEIRLowPLR, !- Cooling Energy Input Ratio Modifier Function of Low Part-Load Ratio Curve Name CoolingEIRHiPLR, !- Cooling Energy Input Ratio Modifier Function of High Part-Load Ratio Curve Name CoolingCombRatio, !- Cooling Combination Ratio Correction Factor Curve Name VRFCPLFFPLR, !- Cooling Part-Load Fraction Correlation Curve Name (cycling losses)

  6. Creating Performance Curves • Raustad, R.A., 2012. Creating Performance Curves for Variable Refrigerant Flow Heat Pumps in EnergyPlus, FSEC-CR-1910-12. https://securedb.fsec.ucf.edu/pub/pub_searchhttps://securedb.fsec.ucf.edu/pub/pub_show_detail?v_pub_id=4588 [59 F] [60.8 F] [64.4 F] [68 F] [71.6 F] [75.2 F] [41 F] [50 F] [86 F] [95 F] [78.8 F] [131] [-4] [F]

  7. Laboratory Measured Data Full-load Cooling Performance [29.4/21.1] [29.4/19.4] [29.4/17.2] [26.7/21.1] [26.7/19.4] [26.7/17.2] [26.7/15.6] [23.8/21.1] [23.9/19.4] [23.8/17.2] AHRI 1230 Buried TSTAT setting [23.9] [20.6] [17.8] [15.0] WB [10] [37.8] [-17.7] [65.6] [C]

  8. Measured part-load operation [15.3 kW] Outdoor Temperature (F) [C] [23.9 C] [29.4 C] [35 C] [40.5 C] Normalized Capacity [26.7 C/ 19.4 C] [15.3 kW] 170 136 102 Capacity (kBtu/hr) 68 34 0

  9. Model Characteristics 170 136 Capacity (kBtu/hr) 102 68 34 [58.6] [kW]

  10. Major Difference between VRF HP’s and Conventional HP’s • Avoid duct losses when using ductless terminal units (no heat gain or leakage)

  11. Major Difference between VRF HP’s and Conventional HP’s • Avoid duct losses when using ductless terminal units (no heat gain or leakage)

  12. Major Difference between VRF HP’s and Conventional HP’s • Avoid duct losses when using ductless terminal units (no heat gain or leakage) • Fan energy savings for ductless terminal units

  13. Major Difference between VRF HP’s and Conventional HP’s • Avoid duct losses when using ductless terminal units (no heat gain or leakage) • Fan energy savings for ductless terminal units • Moderate part-load savings 170 136 Capacity (kBtu/hr) 102 68 34 [58.6] [kW]

  14. Major Difference between VRF HP’s and Conventional HP’s • Avoid duct losses when using ductless terminal units (no heat gain or leakage) • Fan energy savings for ductless terminal units • Moderate part-load savings • Space savings for refrigerant lines vs air ducts

  15. Major Difference between VRF HP’s and Conventional HP’s • Avoid duct losses when using ductless terminal units (no heat gain or leakage) • Fan energy savings for ductless terminal units • Moderate part-load savings • Space savings for refrigerant lines vs air ducts • Individual zone control

  16. Future work • Need more laboratory research and published experimental data • Better understanding of control logic • Field demonstrations need more information • Work closely with manufacturer’s

  17. Questions? Richard Raustad rraustad@fsec.ucf.edu

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