Performance of a Transcritical CO2 Heat Pump for Simultaneous Water Cooling and Heating
This paper presents the experimental as well as the
simulated performance studies on the transcritical CO2 heat pumps
for simultaneous water cooling and heating; effects of water mass
flow rates and water inlet temperatures of both evaporator and gas
cooler on the cooling and heating capacities, system COP and water
outlets temperatures are investigated. Study shows that both the
water mass flow rate and inlet temperature have significant effect on
system performances. Test results show that the effect of evaporator
water mass flow rate on the system performances and water outlet
temperatures is more pronounced (COP increases 0.6 for 1 kg/min)
compared to the gas cooler water mass flow rate (COP increases 0.4
for 1 kg/min) and the effect of gas cooler water inlet temperature is
more significant (COP decreases 0.48 for given ranges) compared to
the evaporator water inlet temperature (COP increases 0.43 for given
ranges). Comparisons of experimental values with simulated results
show the maximum deviation of 5% for cooling capacity, 10% for
heating capacity, 16% for system COP. This study offers useful
guidelines for selecting appropriate water mass flow rate to obtain
required system performance.
[1] P. Neksa, "CO2 heat pump systems," Int. Journal of Refrigeration, vol.
25, no. 4, pp. 421-427, June 2002.
[2] M. H. Kim, J. Pettersen, and C. W. Bullard, "Fundamental process and
system design issues in CO2 vapor compression systems," Progress in
Energy and Combustion Science, vol. 30, no. 2, pp. 119-174, 2004.
[3] P. Neksa, H. Rekstad, G. R. Zakeri, and P. A. Schiefloe, "CO2 heat pump
water heater: characteristics, system design & experimental results," Int.
Journal of Refrigeration, vol. 21, no. 3, pp. 172-179, May 1998.
[4] S. D. White, M. G. Yarrall, D. J. Cleland, and R. A. Hedley, "Modelling
the performance of a transcritical CO2 heat pump for high temperature
heating," Int. Journal of Refrigeration, vol. 25, no. 4, pp. 479-486, June
2002.
[5] M. G. Yarral, S. D. White, D. J. Cleland, R. D. S. Kallu, and R. A.
Hedley, "Performance of transcritical CO2 heat pump for simultaneous
refrigeration and water heating," XX Int. Congress of Refrigeration,
Sydney, 1999, Paper no. 651.
[6] W. Adriansyah, "Combined air conditioning and tap water heating plant
using CO2 as refrigerant," Energy and Buildings, vol. 36, no. 7, pp. 690-
695, July 2004.
[7] J. Stene, "Residential CO2 heat pump system for combined space heating
and hot water heating," Int. Journal of Refrigeration, vol. 28, no. 8, pp.
1259-1265, Dec. 2005.
[8] H. Cho, C. Ryu, Y. Kim, and H. Y. Kim, "Effects of refrigerant charge
amount on the performance of a transcritical CO2 heat pump," Int.
Journal of Refrigeration, vol. 28, no. 8, pp. 1266-1273, Dec. 2005.
[9] S. G. Kim, Y. J. Kim, G. Lee, and M. S. Kim, "The performance of a
transcritical CO2 cycle with an internal heat exchanger for hot water
heating," Int. Journal of Refrigeration, vol. 28, no. 7, pp. 1064-1072,
Nov. 2005.
[10] J. Sarkar, S. Bhattacharyya, and M. Ramgopal, "Simulation of a
transcritical CO2 heat pump cycle for simultaneous cooling and heating
applications," Int. Journal of Refrigeration, vol. 29, no. 5, pp. 735-743,
Aug. 2006.
[11] R. Yokoyama, T. Shimizu, K. Ito, and K. Takemura, "Influence of
ambient temperatures on performance of a CO2 heat pump water heating
system," Energy, vol. 32, no. 4, pp. 388-398, Apr. 2007.
[12] R. Cabello, D. Sa'nchez, R. Llopis, and E. Torrella, "Experimental
evaluation of the energy efficiency of a CO2 refrigerating plant working
in transcritical conditions," Applied Thermal Engineering, vol. 28, no.
13, pp. 1596-1604, Sep. 2008.
[13] J. Sarkar, S. Bhattacharyya, and M. RamGopal, "Optimization of a
transcritical CO2 heat pump cycle for simultaneous cooling and heating
applications," Int. Journal of Refrigeration, vol. 27, no. 8, pp. 830-838,
Dec. 2004.
[14] S. S. Pitla, E. A. Groll, and S. Ramadhyani, "New correlation to predict
the heat transfer coefficient during in-tube cooling of turbulent
supercritical CO2," Int. Journal of Refrigeration, vol. 25, no. 6, pp. 887-
895, Sep. 2002.
[15] X. Fang, C. W. Bullard, and P. S. Hrnjak, "Heat transfer and pressure
drop of gas coolers," ASHRAE Transactions, vol. 107, pp. 255-266,
2001.
[16] V. Gnielinski, "New equations for heat and mass transfer in turbulent
pipe and channel flow," Int. Chemical Engineering, vol. 16, pp. 359-
366, 1976.
[17] S. H. Yoon, E. S. Cho, Y. W. Hwang, M. S. Kim, K Min, and Y. Kim,
"Characteristics of evaporative heat transfer and pressure drop of carbon
dioxide and correlation development," Int. Journal of Refrigeration, vol.
27, no. 2, pp. 111-119, Mar. 2004.
[18] D. S. Jung, and R. Radermacher, "Prediction of pressure drop during
horizontal annular flow boiling of pure and mixed refrigerants," Int.
Journal of Heat Mass Tran., vol. 32, no. 12, 2435-2466, Dec. 1989.
[1] P. Neksa, "CO2 heat pump systems," Int. Journal of Refrigeration, vol.
25, no. 4, pp. 421-427, June 2002.
[2] M. H. Kim, J. Pettersen, and C. W. Bullard, "Fundamental process and
system design issues in CO2 vapor compression systems," Progress in
Energy and Combustion Science, vol. 30, no. 2, pp. 119-174, 2004.
[3] P. Neksa, H. Rekstad, G. R. Zakeri, and P. A. Schiefloe, "CO2 heat pump
water heater: characteristics, system design & experimental results," Int.
Journal of Refrigeration, vol. 21, no. 3, pp. 172-179, May 1998.
[4] S. D. White, M. G. Yarrall, D. J. Cleland, and R. A. Hedley, "Modelling
the performance of a transcritical CO2 heat pump for high temperature
heating," Int. Journal of Refrigeration, vol. 25, no. 4, pp. 479-486, June
2002.
[5] M. G. Yarral, S. D. White, D. J. Cleland, R. D. S. Kallu, and R. A.
Hedley, "Performance of transcritical CO2 heat pump for simultaneous
refrigeration and water heating," XX Int. Congress of Refrigeration,
Sydney, 1999, Paper no. 651.
[6] W. Adriansyah, "Combined air conditioning and tap water heating plant
using CO2 as refrigerant," Energy and Buildings, vol. 36, no. 7, pp. 690-
695, July 2004.
[7] J. Stene, "Residential CO2 heat pump system for combined space heating
and hot water heating," Int. Journal of Refrigeration, vol. 28, no. 8, pp.
1259-1265, Dec. 2005.
[8] H. Cho, C. Ryu, Y. Kim, and H. Y. Kim, "Effects of refrigerant charge
amount on the performance of a transcritical CO2 heat pump," Int.
Journal of Refrigeration, vol. 28, no. 8, pp. 1266-1273, Dec. 2005.
[9] S. G. Kim, Y. J. Kim, G. Lee, and M. S. Kim, "The performance of a
transcritical CO2 cycle with an internal heat exchanger for hot water
heating," Int. Journal of Refrigeration, vol. 28, no. 7, pp. 1064-1072,
Nov. 2005.
[10] J. Sarkar, S. Bhattacharyya, and M. Ramgopal, "Simulation of a
transcritical CO2 heat pump cycle for simultaneous cooling and heating
applications," Int. Journal of Refrigeration, vol. 29, no. 5, pp. 735-743,
Aug. 2006.
[11] R. Yokoyama, T. Shimizu, K. Ito, and K. Takemura, "Influence of
ambient temperatures on performance of a CO2 heat pump water heating
system," Energy, vol. 32, no. 4, pp. 388-398, Apr. 2007.
[12] R. Cabello, D. Sa'nchez, R. Llopis, and E. Torrella, "Experimental
evaluation of the energy efficiency of a CO2 refrigerating plant working
in transcritical conditions," Applied Thermal Engineering, vol. 28, no.
13, pp. 1596-1604, Sep. 2008.
[13] J. Sarkar, S. Bhattacharyya, and M. RamGopal, "Optimization of a
transcritical CO2 heat pump cycle for simultaneous cooling and heating
applications," Int. Journal of Refrigeration, vol. 27, no. 8, pp. 830-838,
Dec. 2004.
[14] S. S. Pitla, E. A. Groll, and S. Ramadhyani, "New correlation to predict
the heat transfer coefficient during in-tube cooling of turbulent
supercritical CO2," Int. Journal of Refrigeration, vol. 25, no. 6, pp. 887-
895, Sep. 2002.
[15] X. Fang, C. W. Bullard, and P. S. Hrnjak, "Heat transfer and pressure
drop of gas coolers," ASHRAE Transactions, vol. 107, pp. 255-266,
2001.
[16] V. Gnielinski, "New equations for heat and mass transfer in turbulent
pipe and channel flow," Int. Chemical Engineering, vol. 16, pp. 359-
366, 1976.
[17] S. H. Yoon, E. S. Cho, Y. W. Hwang, M. S. Kim, K Min, and Y. Kim,
"Characteristics of evaporative heat transfer and pressure drop of carbon
dioxide and correlation development," Int. Journal of Refrigeration, vol.
27, no. 2, pp. 111-119, Mar. 2004.
[18] D. S. Jung, and R. Radermacher, "Prediction of pressure drop during
horizontal annular flow boiling of pure and mixed refrigerants," Int.
Journal of Heat Mass Tran., vol. 32, no. 12, 2435-2466, Dec. 1989.
@article{"International Journal of Mechanical, Industrial and Aerospace Sciences:60461", author = "J. Sarkar and Souvik Bhattacharyya and M. Ramgopal", title = "Performance of a Transcritical CO2 Heat Pump for Simultaneous Water Cooling and Heating", abstract = "This paper presents the experimental as well as the
simulated performance studies on the transcritical CO2 heat pumps
for simultaneous water cooling and heating; effects of water mass
flow rates and water inlet temperatures of both evaporator and gas
cooler on the cooling and heating capacities, system COP and water
outlets temperatures are investigated. Study shows that both the
water mass flow rate and inlet temperature have significant effect on
system performances. Test results show that the effect of evaporator
water mass flow rate on the system performances and water outlet
temperatures is more pronounced (COP increases 0.6 for 1 kg/min)
compared to the gas cooler water mass flow rate (COP increases 0.4
for 1 kg/min) and the effect of gas cooler water inlet temperature is
more significant (COP decreases 0.48 for given ranges) compared to
the evaporator water inlet temperature (COP increases 0.43 for given
ranges). Comparisons of experimental values with simulated results
show the maximum deviation of 5% for cooling capacity, 10% for
heating capacity, 16% for system COP. This study offers useful
guidelines for selecting appropriate water mass flow rate to obtain
required system performance.", keywords = "CO2 heat pump, experiment, simulation,performance characteristics.", volume = "4", number = "8", pages = "689-7", }
