Dynamic Model of a Transcritical CO 2 Heat Pump for Residential Water Heating

Hélio A. G. Diniz, Tiago F. Paulino, Juan J. G. Pabon, Antônio A. T. Maia and Raphael N. Oliveira
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Hélio A. G. Diniz: Graduate Program in Mechanical Engineering, Federal University of Minas Gerais (UFMG), Belo Horizonte 31270-901, Brazil
Tiago F. Paulino: Graduate Program in Mechanical Engineering, Federal Center of Technological Education of Minas Gerais (CEFET-MG), Department of Materials Engineering, Belo Horizonte 30421-169, Brazil
Juan J. G. Pabon: Institute of Mechanical Engineering, Federal University of Itajubá (UNIFEI), Itajubá 35903-087, Brazil
Antônio A. T. Maia: Graduate Program in Mechanical Engineering, Federal University of Minas Gerais (UFMG), Belo Horizonte 31270-901, Brazil
Raphael N. Oliveira: Graduate Program in Mechanical Engineering, Federal University of Minas Gerais (UFMG), Belo Horizonte 31270-901, Brazil

Sustainability, 2021, vol. 13, issue 6, 1-17

Abstract: This paper presents a distributed mathematical model for a carbon dioxide direct expansion solar-assisted heat pump used to heat bath water. The main components are a gas cooler, a needle valve, an evaporator/collector, and a compressor. To develop the heat exchange models, mass, energy, and momentum balances were used. The model was validated for transient as well as steady state conditions using experimental data. A reasonably good agreement was observed between the predicted temperatures and experimental data. The simulations showed that the time step required to demonstrate the behavior of the heat pump in the transient regime is greater than the time step required for the steady state. The results obtained with the mathematical model revealed that a reduction in the water mass flow rate results in an increase in the water outlet temperature. In addition, when the carbon dioxide mass flow rate is reduced, the compressor inlet and outlet temperatures increase as well as the water outlet temperature.

Keywords: dynamic model; carbon dioxide; heat pump; water heating; transcritical cycle (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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