CASE STUDY (CONTINUED)
Test results and conclusions • Tested deviation over a decade: From its original 2007 power test value of 46.8 kW, Compressor One deviated 2.56 percent higher 11 years later (Table 1). Mass flow was 2.13 percent higher. From its original 48.7 kW value, Compressor Two deviated 0.62 percent higher for power consumption (Table 2) and was 0.15 percent higher in mass flow. • Performance consistency: The range of deviation for kW and mass flow (Tables 1 and 2) were all within the acceptable uncertainty limits for performance per AHRI 540-2015.
This range approximates the expected performance values for new compressors. The results show the Danfoss Turbocor® TT300 oil-free compressor experienced no significant performance degradation over an 11-year period. This evidence indicates the compressors provided consistent, long- lasting performance that is likely to extend over the life of the chiller. • Customer satisfaction: Steven C. Miller, senior maintenance specialist for The Hershey Company Data Center, notes that “in a data center, reliability is everything. This chiller with Danfoss Turbocor® TT300
magnetic-bearing compressors has been, and still is, an extremely reliable chiller. Operational and maintenance costs are way down, because there have been very few repairs over the 10+ years this chiller has been in service. We originally selected this technology due to low noise levels and a track record of success at other sites. In our case, the chiller with Danfoss Turbocor® compressors has met and exceeded my expectations regarding performance.”
Table 1: Compressor 1 performance values for Hershey’s Chocolate World data center
TT300 Compressor (90 tons nominal)
Mass Flow Rate (kg/min)
Suction Pressure Discharge Pressure
RPM
Power (kW)
2007 test
359.33
918.88
31905
46.8
101.08
2018 test
362.1
919.75
30656
48.0
103.23
Deviation
0.77%
0.09%
-3.91%
2.56%
2.13%
Table 2: Compressor 2 performance values for Hershey’s Chocolate World data center
TT300 Compressor (90 tons nominal)
Mass Flow Rate (kg/min)
Suction Pressure Discharge Pressure
RPM
Power (kW)
2007 test
353.0
912.39
32002
46.7
100.18
2018 test
354.74
914.91
32005
49.0
100.33
Deviation
0.49%
0.28%
0.01%
0.62%
0.15%
1 “Heating and Cooling.” Energy Star. Accessed October 30, 2018. https://www.energystar.gov/sites/default/files/buildings/tools/EPA_BUM_CH9_HVAC.pdf, page 3. 2 “ASHRAE Research Project Report RP-751: Experimental Determination of the Effect of Oil on Heat Transfer in Flooded Evaporators with R-123, R-134A.” ASHRAE. 1999. 3 Ray Good. “Emerging Oil Free Technologies.” Accessed October 30, 2018. https://utahashrae.org/images/downloads/Chapter_Meeting/slc_ashrae_emerging_oil_ free_technologies_final.pdf, slide 14. 4 “Improving the Energy Efficiency of Air Conditioning and Refrigeration Systems.” Power Knot. Accessed October 30, 2018. http://www.powerknot. com/2017/03/02/improving-the-energy-efficiency-of-air-conditioning-and-refrigeration-systems. 5 Ying Zheng and Michael Bellstedt (Minus40 Pty Ltd). “Final Report: Compressor Degradation Assessment andWear Mitigation Strategy.”Meat & Livestock Australia Limited, North Sydney NSW, Australia. December 2014, page 19.
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