Comparison of Transcritical CO 2 and Conventional Refrigerant Heat Pump Water Heaters for Domestic Applications

Ignacio López Paniagua, Ángel Jiménez Álvaro, Javier Rodríguez Martín, Celina González Fernández and Rafael Nieto Carlier
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Ignacio López Paniagua: E.T.S. Ingenieros Industriales, Universidad Politécnica de Madrid, c/ José Gutierrez Abascal, 2, 28006 Madrid, Spain
Ángel Jiménez Álvaro: E.T.S. Ingenieros Industriales, Universidad Politécnica de Madrid, c/ José Gutierrez Abascal, 2, 28006 Madrid, Spain
Javier Rodríguez Martín: E.T.S. Ingenieros Industriales, Universidad Politécnica de Madrid, c/ José Gutierrez Abascal, 2, 28006 Madrid, Spain
Celina González Fernández: E.T.S. Ingenieros Industriales, Universidad Politécnica de Madrid, c/ José Gutierrez Abascal, 2, 28006 Madrid, Spain
Rafael Nieto Carlier: E.T.S. Ingenieros Industriales, Universidad Politécnica de Madrid, c/ José Gutierrez Abascal, 2, 28006 Madrid, Spain

Energies, 2019, vol. 12, issue 3, 1-17

Abstract: Although CO 2 as refrigerant is well known for having the lowest global warming potential (GWP), and commercial domestic heat pump water heater systems exist, its long expected wide spread use has not fully unfolded. Indeed, CO 2 poses some technological difficulties with respect to conventional refrigerants, but currently, these difficulties have been largely overcome. Numerous studies show that CO 2 heat pump water heaters can improve the coefficient of performance (COP) of conventional ones in the given conditions. In this study, the performances of transcritical CO 2 and R410A heat pump water heaters were compared for an integrated nearly zero-energy building (NZEB) application. The thermodynamic cycle of two commercial systems were modelled integrating experimental data, and these models were then used to analyse both heat pumps receiving and producing hot water at equal temperatures, operating at the same ambient temperature. Within the range of operation of the system, it is unclear which would achieve the better COP, as it depends critically on the conditions of operation, which in turn depend on the ambient conditions and especially on the actual use of the water. Technology changes on each side of the line of equal performance conditions of operation (EPOC), a useful design tool developed in the study. The transcritical CO 2 is more sensitive to operating conditions, and thus offers greater flexibility to the designer, as it allows improving performance by optimising the global system design.

Keywords: heat pump water heater; transcritical CO 2 heat pump; coefficient of performance; near zero-energy building; modelling (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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