variable capacity heat pump rtf sub-committee february 27, 2013 vrf fan energy use and part-load...
TRANSCRIPT
Variable Capacity Heat Pump RTF Sub-Committee
February 27, 2013
VRF Fan Energy Use and Part-Load Performance
Richard Raustad, Senior Research EngineerFlorida Solar Energy Center
Full-Load Cooling Performance
Controlled Region Uncontrolled Region
Full-Load Heating Performance
Manufacturer Performance Correction(surrogate for part-load performance)
72 kBTU/hr 96 kBTU/hr
170
34
68
102
136
Capa
city
(kBt
u/hr
)
0
21 kW 28.1 kW
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)
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_search https://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]
[F][-4] [131]
Laboratory Measured Data
AHRI 1230
Buried TSTAT setting
Full-load Cooling Performance
[C][-17.7] [65.6][37.8][10]
[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][23.9][20.6][17.8][15.0]
WB
Measured part-load operationN
orm
alize
d Ca
paci
ty
[23.9 C]
[29.4 C]
[35 C]
[40.5 C]
Outdoor Temperature (F) [C]
[26.7 C/ 19.4 C]
[15.3 kW]
[15.3 kW]
170
34
68
102
136
Capa
city
(kBt
u/hr
)
0
Model Characteristics
170
34
68
102
136
Capa
city
(kBt
u/hr
)
[kW] [58.6]
Major Difference between VRF HP’s and Conventional HP’s
• Avoid duct losses when using ductless terminal units (no heat gain or leakage)
Major Difference between VRF HP’s and Conventional HP’s
• Avoid duct losses when using ductless terminal units (no heat gain or leakage)
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
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
[kW] [58.6]
170
34
68
102
136
Capa
city
(kBt
u/hr
)
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
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
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
