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Oil Circulation Behavior in Low Temperature CO2 Climate Control Systems
Technical Paper
2004-01-0915
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
This paper presents the oil circulation behavior in a CO2 climate control system operating at low evaporating temperature down to -32°C. The increase of oil circulation ratio (OCR) from 0 to 6 wt.% during steady state conditions degrades the coefficient of performance and cooling capacity by 15% and 8%, respectively. The pressure drop across the heat exchangers increases, especially in the gas cooler. In low temperature CO2 systems some fluctuations of oil and refrigerant flow rates were observed during cyclic operations when the system did not equip the oil separator, but was observed only at high oil charge when the system did equip the oil separator. These instabilities lead to a periodic compressor performance fluctuation, which caused system performance degradations. Therefore, the use of an oil separator is recommended for the low temperature operation if an ordinary metering valve is adopted as an expansion device without any special control strategy.
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Authors
- Yunho Hwang - Center for Environmental Energy Engineering, University of Maryland
- Lorenzo Cremaschi - Center for Environmental Energy Engineering, University of Maryland
- Reinhard Radermacher - Center for Environmental Energy Engineering, University of Maryland
- Toshio Hirata - Denso Corp.
- Yukikatsu Ozaki - Nippon Soken Inc.
- Tadashi Hotta - Nippon Soken Inc.
Citation
Hwang, Y., Cremaschi, L., Radermacher, R., Hirata, T. et al., "Oil Circulation Behavior in Low Temperature CO2 Climate Control Systems," SAE Technical Paper 2004-01-0915, 2004, https://doi.org/10.4271/2004-01-0915.Also In
References
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