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Study of In Situ Performance of the VRF Multi-split Air
Conditioner for the Commercial Building
Hirotaka Hanazaki(TEPCO Energy Partner, Inc.)Satoru Tanaka(Tokyo
Electric Power Company Holdings, Inc.)Hirofumi Ida( Tokyo Electric
Power Company Holdings, Inc.)
Katsumi Hashimoto ( Central Research Institute of Electric Power
Industry )Katsuyuki Edahiro ( DAIKIN INDUSTRIES, LTD. )
Toshihiro Oka( DAIKIN INDUSTRIES, LTD. ) 1
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BACKGROUND
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・The VRF system has been spreading extensively throughout
Japan.
・However, there are few reports on measurement and evaluation of
their performances in situ, due to difficulty of measuring the VRF
system.
・On the other hand, measurement is a indispensable pursuit of
energy conservation.
・In this research, we measured the VRF system in situ.And we did
a study of the performance of the VRF system in situ using the
refrigerant enthalpy (RE) method and the compressor curve (CC)
method.
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LOCATION
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Fig.2 The Building of TEPCO Research Institute
Fig.1 Japn map
◎2009 webmtabi.jp
the VRF system
MEASUREMENTLOCATION
The product under test was the VRF system installed in TEPCO
Research Institute.
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TESTING FACILITY
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Fig.3 The outdoor unit at the rooftop
Outdoor unit(※ The VRF system )
Fig.4 The indoor unit at laboratory
Indoor unit
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MEASUREMENT
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Fig.5 The VRF system and a summary of the instruments installed
around the refrigerant pipes
Table 1. Specifications of the VRF system
Instrument Measurement location during cooling
T-type thermocouple Surface temperature of liquid piping of
outdoor unit [oC]
Surface temperature of vapor piping of outdoor unit [oC]
Pressure sensor [High pressure] Outdoor unit liquid line
pressure [MPa]
[Low pressure] Outdoor unit vapour line pressure [MPa]
Coriolis flow meter Mass flow rate [kg/min] and density [kg/L]
of liquid refrigerant
Power meter Electric power consumption [kW]
T-type thermocouple Atmospheric temperature
Hygrometer Atmospheric humidity
Table 2.The measured parameters
Instrument Outdoor Unit Indoor UnitNumber of Units 1 3Power
supply Three-phase 200V,
50/60HzSingle-phase 200V,
50/60HzRated cooling capacity [kW/Unit] 28.0/28.0 11.2Rated
cooling power consumption [kW/Unit] 8.58 0.165/0.194Rated heating
capacity [kW/Unit] 31.5/31.5 12.5Rated heating power consumption
[kW/Unit] 8.34 0.132/0.161Maximum low-temperature heating
capacity[kW/Unit]
26.7/26.7 ―
Refrigerant R410A
<REFERENCE>Poster sessions P.3.1.2 Study of in Situ Monitoring
Method for(Cooling and Heating) Capacity of Variable Refrigerant
Flow (VRF) Multi-Split Air Conditioners for Commercial
Buildings
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Fig.5 The VRF system and a summary of the instruments installed
around the refrigerant pipes
<REFERENCE>Poster sessions P.3.1.2 Study of in Situ Monitoring
Method for(Cooling and Heating) Capacity of Variable Refrigerant
Flow (VRF) Multi-Split Air Conditioners for Commercial
Buildings
In this research, the performance (capacity and COP) of the VRF
system was estimated using the RE method and the CC method.
■The RE method
The RE method (refrigerant enthalpy method) estimates generated
heat quantities (cooling capacity and heating capacity) by using
the refrigerant mass flow and the refrigerant enthalpy difference
between inlet and outlet of the outdoor unit.
■The CC method
The CC method is the compressor curve method. A manufacturer
uses this method to understand actual performance of the VRF
system.
MEASUREMENT METHOD
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ASCERTAINING COOLING PERFORMANCE
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In this page, cooling performance is described.
The cooling capacity QC,CC and the coefficient of
performanceCOPC,CC were estimated by the CC method from internal
data from the VRF system.
QC,CC
COPC,CC
■The CC method → QC,CC COPC,CC
Cooling capacity QC,RE is estimated by the RE method.QC,RE
COPC,RE Coefficient of performance COPC,RE is calculated from
the QC,RE and the measured power consumption
■The RE method → QC,RE COPC,RE
QC,RE and COPC,RE were compared with QC,CC and COPC,CC
<REFERENCE>Poster sessions P.3.1.2 Study of in Situ Monitoring
Method for(Cooling and Heating) Capacity of Variable Refrigerant
Flow (VRF) Multi-Split Air Conditioners for Commercial
Buildings
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ASCERTAINING COOLING PERFORMANCE
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X axis:Cooling capacity estimated by CC method, QC,CCY axis:The
cooling capacity difference between measurement (RE method) and CC
method
(QC,RE - QC,CC)
Fig.6 Comparison of Cooling Capacity Values Between the
Measurement and the CC Method
① In the low load factor region,measurement value was larger
than estimated value by CC method.
② In the high load factor region, the results show a slightly
disparity within ±10% between the RE method estimated value and the
CC method estimated value.
②①
Comparison of Cooling Capacity Values
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ASCERTAINING COOLING PERFORMANCE
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Comparison of Power Consumption Values
①For power consumption, the measured value PRE was smaller than
internal data PCC for the whole range. PRE was lower than PCC by
0.3~0.5kW over the whole range.
Fig.7 Comparison of Power Consumption Values
①
X axis: Cooling capacity estimated by CC method, QC,CCY axis:The
difference between the measured power consumption value, PRE,
and
the power consumption value estimated by the CC method, PCC
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ASCERTAINING COOLING PERFORMANCE
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①For COP, measurement is larger than CC method estimated value
over the whole range. The divergence between Measurement and CC
method estimated value was particularly large in the low load
factor region.
Fig.8 COP Comparison
①
COP Comparison
X axis: Cooling capacity estimated by CC method, QC,CC,Y
axis:The difference between Measurement and CC method estimates of
COP,
(COPC,RE - COPC,CC)
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ASCERTAINING COOLING PERFORMANCE
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①In the high load factor region, COPC,RE is close to the catalog
value of 3.26 (*rated cooling capacity/rated power consumption)
② COPC,RE increased as load factor approached 30% in the low
load factor region.
Fig.9 Relationship Between Load Factor and COP
※COP3.26
①
②
Ascertaining COP Under Partial Load
X axis:Load factor (=instantaneous output / rating capacity)Y
axis:Cooling COP (Measurement)
Ascertaining COP Under Partial Load
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① The lower the load factor, the lower the power
consumption.
②In the 0.2~0.9 load factor range, power consumption is smaller
than the straight line between 0 and the rated power consumption
8.58kW.
Fig.10 Relationship Between Load Factor and power consumption in
Cooling
The straight line connected 0 with the rated power consumption
8.58kW
①
②
Relationship Between Load Factor and Power Consumption
X axis:Load factor (=instantaneous output / rating capacity)Y
axis:Power consumption (Measurement)
ASCERTAINING HEATING PERFORMANCE
8.58kW
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CONCLUSION
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・In this research, the measurement of the VRF system was
successfully conducted. And the cooling performances (cooling
capacity ,cooling load factor and cooling COP) could be estimated
by the RE method and the CC method .
Measurement・The performances by the RE method are compared with
one by the CC method
・While measurement accuracy by RE method is high, simplification
is necessary toimprove usability.
Performance of VRF system・In the high load factor region,
COPC,RE is close to the catalog value of 3.26 (*rated cooling
capacity/rated power consumption)
・Cooling COP increased as cooling load factor decreased. It is
confirmed that theimprovement of the VRF system is achieved
properly.