Korean Journal of Air-Conditioning and Refrigeration Engineering (설비공학논문집)

The Society of Air-Conditioning and Refrigerating Engineers of Korea (대한설비공학회)
권호 표지
DOI QR코드

DOI QR Code

An Experimental Study on the Effects of Operating Variables on the Cooling and Heating Performance of Geothermal Heat Pump

지열 히트펌프에서 운전변수가 냉난방 성능에 미치는 영향에 대한 실험연구

  • Received : 2011.04.06
  • Published : 2011.08.10
Download PDF
⟨ Previous Next ⟩

Abstract

In this research, an experimental study is performed to investigate the effects of system operating variables on the cooling and heating characteristics of heat pump system using geothermal heat source and carbon dioxide as a refrigerant. System variables analyzed include compressor frequency, electronic expansion valve opening, refrigerant charge, secondary fluid temperature and flow rate. Results show that optimum refrigerant charge and electronic expansion valve opening position exist at the maximum point of COP curve, and both cooling and heating capacity increase but COPs decrease with the increase of compressor frequency. The change of a secondary fluid temperature leads to variation of overheat area and enthalpy difference in the evaporator and gas cooler. which again results in considerable variations of cooling and heating capacity and COP. In the case of effects of secondary water fluid flow rate, both cooling capacity and COP increase with the increase of secondary flow in evaporator or gas cooler, whereas heating capacity and COP decrease with the increase of flow rate in gas cooler.

Keywords

References

  1. Choi, J. M., Kang, S. H., Choi, J. H., Lim, H. J., Moon, J. M., Kwon, Y. S., Kwon, H. J., and Kim, R. H., 2009, Verification Experiment of a Ground Source Multi-Heat Pump at Cooling Mode, Korean Journal of Air-Conditioning and Refrigeration Engineering, Vol. 21, No. 5, pp. 297-304.
  2. Standard for Equipment Inspection(New and Renewable Energy)-Water-to-water Heat Pump Unit, NR GT 101:2008, KEMCO.
  3. Kim, Y. L. and Kim., S. C., 2008, A Study on the Improvement of the Heating Performance of the Ground Source Heat Pump Using $CO_{2}$ as a Refrigerant, J. of Industrial Technology, KITECH, Vol. 18, pp. 73-86.
  4. Neksa, P., Rekstad, H., Zakeri, R., 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. https://doi.org/10.1016/S0140-7007(98)00017-6
  5. Cho, H. H., Ryu, C. G. and Kim, Y. C., 2005, Experimental Study on the Cooling Performance of a Variable Speed $CO_2$ Cycle with Internal Heat Exchanger and Electronic Expansion Valve, Korean Journal of Air-Con ditioning and Refrigeration Engineering, Vol. 17, No. 3, pp. 209-215.
  6. Cho, H. H., Ryu, C. G., Lee, H. S. and Kim, Y. C., 2005, Experimental Study on the Variation of the Optimal Charge with cycle option in the $CO_2$ Refrigeration, Proceedings of the SAREK, pp. 398-403.
  7. Lee, E. C., Baek, C. H., Kang, H., Kim, Y. C., Cho, H. H. and Cho, S. W., 2009, Experimental Study on the Performance of a $CO_2$ Heat Pump Water Heater, Korean Journal of Air- Conditioning and Refrigeration Engineering, Vol. 21, No. 6, pp. 367-372.
  8. Chen, Y., Gu, J., 2005, The Optimum High Pressure for $CO_2$ Transcritical Refrigeration System with Internal Heat Exchanger, Int. Journal of Refrigeration, Vol. 28, No. 8, pp. 1238-1249. https://doi.org/10.1016/j.ijrefrig.2005.08.009
  9. Qureshi, T. Q. and Tassou, S. A., 1996, Variable speed capacity control in refrigeration system, Applied Thermal Engineering Vol. 16, No. 2, pp. 103-113. https://doi.org/10.1016/1359-4311(95)00051-E
  10. Ha, J. H., Kim, Y. C. and Choi, J. M., 1999, Experimental study on the superheat control of the variable speed heat pump, Proceedings of the SAREK Winter Annual Conference, pp. 527-533.
  11. Cho, H. H., Ryu, C. G., Kim, Y. C., and Sim, Y. H., 2005, Effects of Refrigerant Charge Amount on the Cooling Performance of a Transcritical $CO_2$ Cycle, International Journal of Air-Conditioning and Refrigeration Engineering, Vol. 17, No. 5, pp. 410-417.
  12. Rieberer, R., Neksa, P. and Schiefloe, P, A., 1999, $CO_2$ heat pumps for space heating and tap water heating, 20th International Congress of Refrigeration, IIR/IIF, Sydney.
  13. Rieberer, R., Gassler, M. and Halozan, H., 2000, Control of $CO_2$ heat pumps, Proceedings of the 4th IIR-Gustav Lorentzen Conference on Natural Working Fluids at Purdue, 25-28; West Lafayette, USA, pp. 75-82.
  14. Bivens, D. B., Allgood, C. C., Shiflett, M. B., Patron, D. M., Chisolm, T. C., Shealy, G. S., Yokozeki, A., Wells, W. D., and Geiger, K. A., 1994, HCFC-22 alternative for air conditioners and heat pumps, ASHRAE Transaction, Vol. 100, No. 2, pp. 566-572.
  15. Bullock, C. E., 1997, Theoretical performance of carbon dioxide in subcritical and transcritical cycle, ASHRAE/NIST Conference Refrigerants for the 21st Century, Gaithersburg, Maryland, USA, pp. 20-26.
  16. Boewe, D. E., Bullard, C. W., Yin, J. M., and Hrnjak, P. S., 2001, Contribution of internal heat exchanger to transcritical R-744 cycle performance, HVAC&R Research, Vol. 7, No. 2, pp. 155-168. https://doi.org/10.1080/10789669.2001.10391268