Modeling and experimental analysis of the solar radiation in a CO2 direct-expansion solar-assisted heat pump

Paulino, Tiago de Freitas; Oliveira, Raphael Nunes de; Maia, Antônio Augusto Torres; Palm, Björn; Machado, Luiz

doi:10.1016/j.applthermaleng.2018.11.045

Cited by 38 publications

(8 citation statements)

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“…Accordingly, the authors suggest using a static expansion device as a capillary tube, thus reducing the costs of this equipment. However, the results on a direct expansion SAHP using CO 2 discussed in the study by Paulino et al [ 39 ] showed that a small variation of the solar radiation leads to a significant variation in the superheat, therefore requiring an immediate action of the expansion device. Therefore, the use of an electronic expansion valve (EEV) was suggested, which allows a steady and continuous flow of refrigerant.…”

Section: Solar‐coupled Vapor‐compression Heat Pumps For Space Heating...mentioning

confidence: 99%

Analysis of the Potential of Solar‐Assisted Heat Pumps: Technical, Market, and Social Acceptance Aspects

2022

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Solar‐assisted heat pumps have the potential to increase the share of renewables in the energy systems for several cases, or to increase the flexibility of smart grids and integrated thermal‐electric grids. The development of such systems requires a comprehensive approach in which technical, market, and social acceptance are all tackled at the same time. Such a holistic approach is the main objective of the present review article. To do so, an investigation is performed by categorizing the integration approaches reported in the literature, exploiting the solar source either as a low‐temperature evaporator source or as supporting the condenser during heating operation. Furthermore, hybrid integration schematics and dual‐source approaches are discussed. Market and social aspects complete the analysis, with the aim of finally identifying the current status; the main drivers and challenges are also addressed. The reported results confirm that the exploitation of solar thermal energy can increase the achievable performance of heat pumps in a broad range of climates. A favorable regulatory/financial framework and informative campaigns for businesspersons and the wide public have been identified as the main solutions to maximize the deployment of the technology in the coming years.

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Section: Solar‐coupled Vapor‐compression Heat Pumps For Space Heating...mentioning

confidence: 99%

Analysis of the Potential of Solar‐Assisted Heat Pumps: Technical, Market, and Social Acceptance Aspects

2022

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“…The results showed that when the solar radiation is high, a high degree of superheat is observed at the collector's outlet and the performance of the heat pump is penalized by reduction in the evaporating area [6]. In a previous numerical work on the same heat pump system, Paulino et al [7] suggested the use of an electronic expansion valve to control the refrigerant mass flow rate at the evaporator inlet, and so the value of the superheating at the collector's outlet.…”

Section: Introductionmentioning

confidence: 97%

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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“…Paulino et al. 26 reported that using an electronic expansion valve has improved the performance of a DXSTHPS by varying the refrigerant mass flow rate through the flat plate collector-evaporator according to the sunshine availability. Yerdesh et al.…”

Section: Introductionmentioning

confidence: 99%

“…The R134a performs better than R744 at high ambient temperatures. Paulino et al 26 reported that using an electronic expansion valve has improved the performance of a DXSTHPS by varying the refrigerant mass flow rate through the flat plate collectorevaporator according to the sunshine availability. Yerdesh et al 27 reported that R744 and R290 combination (R744 in the low-temperature circuit and R290 in the high-temperature circuit) is a good environmentally friendly option for a two-stage cascade heat pump owing to its negligible GWP.…”

Section: Introductionmentioning

confidence: 99%

Experimental studies on direct expansion solar thermal heat pump systems using R430A as a substitute to R134a

Mohanraj

Kartheheyan

2021

Proceedings of the Institution of Mechanical Engineers, Part E:

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The use of halogen-based refrigerants in heat pump applications is restricted because of their high global warming potential (GWP). Therefore, it is necessary to identify a low GWP substitute for heat pump applications. This article presents the energy performance of a direct expansion solar thermal heat pump system (DXSTHPS) using R430A as an environmentally friendly substitute to phase out R134a. The effects of ambient parameters on compressor discharge temperature, compressor energy consumption, condenser heating capacity and coefficient of performance (COP) of a DXSTHPS using R134a and R430A are estimated and compared. Moreover, the total equivalent global warming impacts (TEGWI) of a DXSTHPS using R134a and R430A are evaluated. The results showed that the R430A has 0.7–1.9% lower compressor energy consumption than R134a. The condenser heating capacity and COP of a DXSTHPS using R430A are higher than R134a by 4.6–8.7% and 5.1–10.2%, respectively. The compressor discharge temperature observed in a DXSTHPS using R430A is 5.8 °C higher than R134a. The lubricant physical properties are retained at higher compressor operating temperatures, ensuring compressor reliability. The DXSTHPS using R430A has 4.2–12.9% lower TEGWI due to its lower GWP with lower compressor energy consumption than R134a.

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Modeling and experimental analysis of the solar radiation in a CO2 direct-expansion solar-assisted heat pump

Cited by 38 publications

References 50 publications

Analysis of the Potential of Solar‐Assisted Heat Pumps: Technical, Market, and Social Acceptance Aspects

Analysis of the Potential of Solar‐Assisted Heat Pumps: Technical, Market, and Social Acceptance Aspects

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

Experimental studies on direct expansion solar thermal heat pump systems using R430A as a substitute to R134a

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Modeling and experimental analysis of the solar radiation in a CO2 direct-expansion solar-assisted heat pump

Cited by 38 publications

References 50 publications

Analysis of the Potential of Solar‐Assisted Heat Pumps: Technical, Market, and Social Acceptance Aspects

Analysis of the Potential of Solar‐Assisted Heat Pumps: Technical, Market, and Social Acceptance Aspects

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

Experimental studies on direct expansion solar thermal heat pump systems using R430A as a substitute to R134a

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Product

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