Experimental Analysis of the Influence of Water Mass Flow Rate on the Performance of a CO2 Direct-Expansion Solar Assisted Heat Pump
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Experimental Analysis of the Influence of Water Mass Flow Rate on the Performance of a CO2 Direct-Expansion Solar Assisted Heat Pump

Authors: Sabrina N. Rabelo, Tiago de F. Paulino, Willian M. Duarte, Samer Sawalha, Luiz Machado

Abstract:

Energy use is one of the main indicators for the economic and social development of a country, reflecting directly in the quality of life of the population. The expansion of energy use together with the depletion of fossil resources and the poor efficiency of energy systems have led many countries in recent years to invest in renewable energy sources. In this context, solar-assisted heat pump has become very important in energy industry, since it can transfer heat energy from the sun to water or another absorbing source. The direct-expansion solar assisted heat pump (DX-SAHP) water heater system operates by receiving solar energy incident in a solar collector, which serves as an evaporator in a refrigeration cycle, and the energy reject by the condenser is used for water heating. In this paper, a DX-SAHP using carbon dioxide as refrigerant (R744) was assembled, and the influence of the variation of the water mass flow rate in the system was analyzed. The parameters such as high pressure, water outlet temperature, gas cooler outlet temperature, evaporator temperature, and the coefficient of performance were studied. The mainly components used to assemble the heat pump were a reciprocating compressor, a gas cooler which is a countercurrent concentric tube heat exchanger, a needle-valve, and an evaporator that is a copper bare flat plate solar collector designed to capture direct and diffuse radiation. Routines were developed in the LabVIEW and CoolProp through MATLAB software’s, respectively, to collect data and calculate the thermodynamics properties. The range of coefficient of performance measured was from 3.2 to 5.34. It was noticed that, with the higher water mass flow rate, the water outlet temperature decreased, and consequently, the coefficient of performance of the system increases since the heat transfer in the gas cooler is higher. In addition, the high pressure of the system and the CO2 gas cooler outlet temperature decreased. The heat pump using carbon dioxide as a refrigerant, especially operating with solar radiation has been proven to be a renewable source in an efficient system for heating residential water compared to electrical heaters reaching temperatures between 40 °C and 80 °C.

Keywords: Water mass flow rate, R-744, heat pump, solar evaporator, water heater.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1317384

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References:


[1] Hepbasli, A.; Kalinci, Y. A review of heat pump water heating systems. Renewable and Sustainable Energy Reviews, n.12, p.1211-1229, 2009.
[2] NEEA, Heat Pump Water Heater Model Validation Study, in, Northwest Energy Efficiency Alliance, p. 74-75, 2015.
[3] Willem, H.; Lin, Y.; Lekov, A. Review of Energy Efficiency and System Performance of Residential Heat Pump Water Heaters, Energy and Buildings, v.143, p.191-201, 2017
[4] Kong, X. Q.; Li, Y.; Lin, L. e Yang, Y. G. Modeling evaluation of a direct-expansion solar-assisted heat pump water heater using R410A. International Journal of Refrigeration, v. 76, p. 136-146, 2017.
[5] Omojaro, P.; Breitkopf, C. Direct Expansion solar assisted heat pumps: A review of applications and recent research. Renewable and Sustainable Energy Reviews, v.22, p.33-45, 2013.
[6] Kuang, Y. H., Sumathy, K., Wang, R.Z. Study on a direct-expansion solar-assisted heat pump water heating system. International Journal of Energy Research, v. 27, p. 531-548, 2003.
[7] Chow, T. T.; Pei, G.; Fong, K. F.; Lin, Z.; Chan, A. L. S. e He, M. Modeling and application of direct-expansion solar-assisted heat pump for water heating in subtropical Hong Kong. Applied Energy, v.87, p. 643-649, 2010.
[8] Kong, X. Q. Zhang, D.; Li. Y.; Yang, Q. M. Thermal performance an analysis of a direct- expansion solar- assisted heat pump water heater. Energy, v.36, n.12, p. 6830-6838, 2011.
[9] Mota-Babiloni, A.; Makhnatch, P.; Khodabanceh, R. Recent investigations in HFCs substitution with lower GWP synthetic alternatives: focus on energetic performance and environmental impact. International Journal of Refrigeration, v.82, p.288-301, 2017.
[10] Austin, B. T.; Sumathy, K. Transcritical carbon dioxide heat pump systems: A review. Renewable and Sustainable Energy Reviews, v.15, p.4013-4029, 2011.
[11] Ma, Y., Liu, Z., Tian, H. A review of transcritical carbon dioxide heat pump and refrigeration cycles. Energy, v.55, 156–172, 2013.
[12] Neksá, Petter. CO2 heat pump systems. International Journal of Refrigeration, v. 25, p. 421-427, 2002.
[13] Sarkar, J.; Bhattacharyya, S.; Ramgopal, M. Performance of a transcritical CO2 heat pump for simultaneous water cooling and heating. International Journal of Engineering and Applied Sciences, v.16, p. 57-63, 2010.
[14] Sarkar, J.; Bhattacharyya, S. Operating characteristics of transcritical CO2 heat pump for simultaneous water cooling and heating. Archives of thermodynamics, n.4, v.33, p.23-40, 2012.
[15] Yokoyama, R.; Wakaui, T.; Kamakari, J.; Takemura, K.; Performance analysis of a CO2 heat pump water heating system under a daily change in a standardized demand. Energy, v. 35, p. 718-728, 2010.
[16] Minetto, Sìlvia. Theorical and experimental analysis of a CO2 heat pump for domestic hot water. International Journal of Refrigeration, v. 34, p.742-751, 2011.
[17] Cecchinato, L.; Corradi, M.; Minetto, S. A critical approach to the determination of optimal heat rejection pressure in transcritical systems. Applied Thermal Engineering, v.30, p.1812-1823, 2010.
[18] Cecchinato, L.; Corradi, M.; Minetto, S. A simplified method to evaluate the energy performance of CO2 heat pump units. International Journal of Thermal Sciences, v.50, p.2483-2495, 2011.
[19] Cecchinato, L.; Corradi, M.; Minetto, S.; Stringari. P.; Zilio. C, Thermodynamic analysis of different two-stage transcritical carbon dioxide cycles. International Journal of Refrigeration, v.32, p. 1058-1067, 2009.
[20] Yamaguchi, S.; Kato, D.; Saito, K.; Kawai, S. Development and validation of static simulation model for CO2 heat pump. International Journal of Heat and Mass Transfer, v. 54, p. 1896-1906, 2011.
[21] Xu, X. X.; Chen, G. M.; Tang, L. M.; Zhu, Z. J. Experimental investigation on performance of transcritical CO2 heat pump system with ejector under optimum high-side pressure. Energy, v.44, p-870-877, 2012.
[22] Lin, K.; Kuo, C.; Hsieh, W.; Wang, C. Modeling and simulation of the transcritical CO2 heat pump system. International Journal of Refrigeration, v.36, p.2048-20654, 2013.
[23] Purohit, N.; Gupta, D. K.; Dasgupta, M. S. Thermodynamic Analysis of Trans-Critical CO2 refrigeration Cycle in Indian Context. International Journal of Scientific and Technical Advancements, v.1. p.143-146, 2015.
[24] Rawat, K. S.; Bisht, V. S.; Pratibar, A. K. Thermodynamic Analysis and Optimization CO2 based Trasncritical Cycle. International Journal for Research in Applies Science and Engineering Technology, v. 3, p. 287-293, 2015.
[25] Oliveira, R. N.; Faria, R. N.; Antonanzas-Torres. F.; Machado. L.; Koury. R. N. N. Dynamic model and experimental validation for gas cooler of CO2 heat pump for heating residential water. Science and Technology for Built Environment, v.1, p.1-11, 2015.
[26] Faria, R. N.; Nunes, R. O.; Koury, R. N. N.; Machado. L. Dynamic modeling study for a solar evaporator with expansion valve assembly of transcritical heat pump. International Journal of Refrigeration, 2016. DOI: 2016.01.004.
[27] Duffie, J. A. e Beckman, W. A. Solar engineering of thermal processes. 4th edition, Hoboken: John Wiley and Sons, 2013.
[28] Bipm, I. E. A. evaluation of Measurement Data—Guide to the Expression of Uncertainty in Measurement GUM 1995 with minor corrections. Joint Committee for Guides in Metrology, JCGM, 2008.
[29] Wang, S.; Tuo, H.; Xing, Z. Experimental investigation on air-source transcritical CO2 heat pump water heater system at a fixed water inlet temperature. International Journal of Refrigeration, v.36, p.701-716, 2013.