Experimental performance analysis of a CO2 direct-expansion solar assisted heat pump water heater

Duarte, Willian Moreira; Rabelo, Sabrina Nogueira; Paulino, Tiago F.; Pabón, Juan José García; Machado, Luiz

doi:10.1016/j.ijrefrig.2021.01.008

Cited by 27 publications

(3 citation statements)

References 52 publications

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“…In the literature, few experimental studies on direct solar-assisted heat pumps (DX-SAHPs) working with CO2 as the refrigerant are available. Duarte et al [5] analyzed the performance of a CO2 heat pump with a sheet-and-tube solar thermal collector as evaporator. The surface temperature of the solar evaporator was experimentally measured with an infrared camera.…”

Section: Introductionmentioning

confidence: 99%

Control of CO₂ evaporation in an integrated photovoltaic module: experiments and modelling

Azzolin,

Zanetti,

Conte

et al. 2024

J. Phys.: Conf. Ser.

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The use of environmentally friendly refrigerants and the improvement of the system performance are two main topics in the research on heat pump technology. Given the recent limitations imposed on the usage of high global warming potential refrigerants, there is a growing demand in the market for the adoption of natural refrigerants, like CO2. Nevertheless, CO2 heat pumps operate under transcritical conditions, which can adversely affect its efficiency. Therefore, incorporating a solar heat source into a CO2 heat pump can offer a solution to mitigate low system performance issues. In the present study, a photovoltaic module integrated with the evaporator of a CO2 heat pump is experimentally studied. The PV-T evaporator exploits solar radiation to both generate electricity in the PV cells and ensure the evaporation of CO2 in the collector’s tubes. Simultaneously, the PV conversion efficiency is improved by the cooling effect of the evaporation. The present evaporator works in dry expansion mode, thus the refrigerant flow after the expansion device is sent to the solar collectors, where it evaporates before returning to the compressor. When using a PV-T evaporator, it is necessary to prevent superheating in the evaporator to keep a uniform and efficient cooling of the PV cells. The current heat pump design prevents the occurrence of superheated vapor at the PV-T evaporator’s outlet. Beside the experimental activity a dynamic numerical model of the system has been developed and validated.

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Section: Introductionmentioning

confidence: 99%

Control of CO₂ evaporation in an integrated photovoltaic module: experiments and modelling

Azzolin,

Zanetti,

Conte

et al. 2024

J. Phys.: Conf. Ser.

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“…Replacing electric heaters by heat pumps has several advantages such as reducing operating costs, reducing energy consumption, and reducing greenhouse gas emissions. According to recent studies, employing renewable energies like solar energy [1][2][3], geothermal energy [4][5][6], wind power [7] and bio-gas [8] is one way to increment the COP of the heat pumps. Different Solar-Assited Heat Pump (SAHP) setups that were found in the literature review presented by Buker and Riffat [9].…”

Section: Introductionmentioning

confidence: 99%

Experimental Validation Through a Parallel Computation Algorithm for Evaluation Uncertainty of the Mathematical Model of Direct Expansion Solar Assisted Heat Pump

Duarte

Paulino

Duarte

et al. 2023

J. Solar Eneg. Res. Updat.

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This paper presents the development of a mathematical model for a direct-expansion solar-assisted heat pump (DX-SAHP) operating in steady-state. The mathematical model was implemented using the scientific software EES and using a code written in Python. It was utilized a lumped parameter model for the heat exchangers and a semi-empirical model for the compressor. The mathematical model was validated using experimental data of a DX-SAHP running with R134a. Two hundred simulations were made combining different correlations for estimating the convective heat transfer coefficient in the evaporator/collector. The Mean Absolute Deviation (MAD) and the Mean Deviation (MD) between the theoretical and experimental values for the COP were 2.6±1.8 % and 0.9±1.8 %, respectively. The MAD and MD between the discharge temperature were 1.56±0.16 % and -1.45±0.16 %. The mean difference between the results using EES and Python were 1.4 %. The use of Python with parallel computing for uncertainty analyses, reduced the simulation time in 88 % if compared with EES. The model in Python is available as open-source through the platform Google Colaboratory.

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“…El rendimiento experimental de un sistema DX-SAHP con CO2 fue analizado por Duarte et al [7]. La válvula de expansión utilizada fue de tipo aguja, diseñada para trabajar únicamente con CO2 y un orificio de salida con un área de 1.6 mm 2 .…”

Section: Introductionunclassified

Evaluación del rendimiento de una bomba de calor de expansión directa asistida por energía solar mediante simulación numérica del proceso de estrangulamiento en el dispositivo de expansión

Simbaña

Quitiaquez

Estupiñán

et al. 2022

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La evaluación del rendimiento de una bomba de calor de expansión directa asistida por energía solar (DX-SAHP, por sus siglas en inglés) fue analizada mediante simulación numérica del proceso de estrangulamiento en el dispositivo de expansión. Los valores experimentales de operación del sistema fueron validados mediante prueba de normalidad con 95 % de confianza. Una válvula de expansión E2V09SSF fue modelada para el análisis numérico en el módulo Fluent del software ANSYS. El mejor mallado de la válvula generó 263524 elementos y 50449 nodos con una métrica excelente, de 0.2334 de skewness. La temperatura y presión del refrigerante fueron definidas como condiciones de contorno en la entrada del dispositivo de expansión, además de la velocidad. Se utilizaron las ecuaciones de continuidad, momento y energía, considerando un modelo k-epsilon RNG. La presión del refrigerante al salir del dispositivo de expansión obtenidos mediante simulación se comparó con valores experimentales determinados en el prototipo de un sistema DX-SAHP. La presión del refrigerante obtenida mediante simulación para un tiempo de calentamiento de 0 a 40 minutos fue de 161.61, 186.50 y 238.33 kPa. El error absoluto entre la presión experimental y simulada fue de 4.07 kPa, mientras que el error relativo fue inferior a 2 %.

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Experimental performance analysis of a CO2 direct-expansion solar assisted heat pump water heater

Cited by 27 publications

References 52 publications

Control of CO₂ evaporation in an integrated photovoltaic module: experiments and modelling

Control of CO₂ evaporation in an integrated photovoltaic module: experiments and modelling

Experimental Validation Through a Parallel Computation Algorithm for Evaluation Uncertainty of the Mathematical Model of Direct Expansion Solar Assisted Heat Pump

Evaluación del rendimiento de una bomba de calor de expansión directa asistida por energía solar mediante simulación numérica del proceso de estrangulamiento en el dispositivo de expansión

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Experimental performance analysis of a CO2 direct-expansion solar assisted heat pump water heater

Cited by 27 publications

References 52 publications

Control of CO2 evaporation in an integrated photovoltaic module: experiments and modelling

Control of CO2 evaporation in an integrated photovoltaic module: experiments and modelling

Experimental Validation Through a Parallel Computation Algorithm for Evaluation Uncertainty of the Mathematical Model of Direct Expansion Solar Assisted Heat Pump

Evaluación del rendimiento de una bomba de calor de expansión directa asistida por energía solar mediante simulación numérica del proceso de estrangulamiento en el dispositivo de expansión

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Control of CO₂ evaporation in an integrated photovoltaic module: experiments and modelling

Control of CO₂ evaporation in an integrated photovoltaic module: experiments and modelling