Browse > Article

Simulation Study on the Performance Improvement of a $CO_2$ System Applying a Two-stage Phase-separate Cycle  

Ryu Chang-Gi (Graduate School of Mechanical Engineering, Korea University)
Lee Ho-Seong (Graduate School of Mechanical Engineering, Korea University)
Kim Yong-Chan (Department of Mechanical Engineering, Korea University)
Cho Hong-Hyun (Samsung Electronics Co. Ltd.)
Cho Sung-Wook (Samsung Electronics Co. Ltd.)
Publication Information
Korean Journal of Air-Conditioning and Refrigeration Engineering / v.18, no.8, 2006 , pp. 641-648 More about this Journal
Abstract
In this study, a two-stage phase-separate cycle was investigated analytically to improve the performance of the $CO_2$ system in the cooling mode. The simulation results were verified with the measured data. The predictions using the simulation model were consistent with the measured data within ${\pm}20%$ deviations. The performance of the modified $CO_2$ system with the two-stage phase-separated cycle was analyzed with the variations of outdoor temperature and EEV opening. The cooling COP decreased with the increase of compressor frequency. The highest COP was 2.7 at compressor frequencies of 30 Hz and 30 Hz for the first and second compressors, respectively. In addition, the cooling COP increased by 9.3% with an application of optimum control of the first and second-stage EEV openings.
Keywords
Carbon dioxide; Transcritical cycle; Two-stage compression cycle; Phase-separate cycle;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Huff, H., Hwang, Y. and Radermarcher, R., 2002, Options for a two-stage transcritical $CO_2$ cycle, 5th IIR-Gustav Lorentzen on Natural Working Fluids Conference at Guangzhou, pp.143-149
2 Sievers, U., 2005, Thermodynamic process calculations for $CO_2$ refrigeration plants with two-stage compression, IIR international conference at Vicenza
3 Gungor, K. and Winterton, R., 1986, A general correlation for flow boiling in tubes and annuli, Int. Journal Heat and Mass Transfer, Vol. 29, pp.351-358   DOI   ScienceOn
4 Chang, Y. and Wang, C., 1997, A generalized heat transfer correlation for louver fin geometry, Journal of Heat and Mass Transfer, Vol. 40, No.3, pp.533-544   DOI   ScienceOn
5 Gnielinski, V., 1976, New equation for heat and mass transfer in turbulent pipe and channel flow, Int. Chemical Engineering, Vol. 16, pp.359-368
6 Jung, D. and Radermacher, R., 1989, Prediction of pressure drop during horizontal annular flow boiling of pure and mixed refrigerants, Int. Journal of Heat and Mass Transfer, Vol. 32, No. 12, pp.2435-2466   DOI   ScienceOn
7 Hwang, Y., Celik, A. and Radermacher, R., 2004, Performance of $CO_2$ cycles with a twostage compressor, International Refrigeration and Air Conditioning Conference at Purdue
8 ASHRAE, 1983, Methods of testing for seasonal efficiency of unitary air-conditioner and heat pumps, ASHRAE Standard 116
9 Churchill, S., 1997, Friction factor equation spans all fluid flow regimes, Chemical Engineering, Vol. 7, pp.91-92
10 Neksa, P., Rekstad, H., Zakeri, R. and Schiefloe, P., 1998, $CO_2$ heat pump water heater: characteristics, system design and experimental results, Int. Journal of Refrigeration, Vol. 21, No.3, pp. 172-179   DOI   ScienceOn
11 Groll, E., Baek, J. and Lawless, P., 2002, Effect of pressure ratios across compressors on the performance of the transcritical $CO_2$ cycle with two-stage compression and intercooling, Compressor Engineering Conference at Purdue, R11-7
12 Rice, C. and Fisher, S., 1983, A steady state computer design model for air to air heat pump, Department of Energy, division of building equipment, ORNL
13 Webb, R., 1992, Principles of enhanced heat transfer, Willey, New York, pp. 138-139