Effects of using expander and internal heat exchanger on carbon dioxide direct-expansion geothermal heat pump

Ghazizade–Ahsaee, Hossein; Ameri, Mehran

doi:10.1016/j.applthermaleng.2018.03.032

Cited by 28 publications

(3 citation statements)

References 35 publications

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“…using carbon dioxide direct-expansion ground source heat pump (CO2-DX-GSHP) [172], carbon dioxide direct-expansion geothermal heat pump [173], transcritical CO2 heat pump integrated with thermal energy storage [174], geothermal heat pump working with different zeotropic and azeotropic mixtures [175]. Wang et al [176] investigated a novel CO2 heat pump system with Series Gas Cooler (SGC) for the application in an electrical vehicle (EV).…”

Section: Enhanced Oil and Gas Recoverymentioning

confidence: 99%

Flexible Carbon Capture and Utilization technologies in future energy systems and the utilization pathways of captured CO2

Mikulčić

Skov

Dominković

et al. 2019

Renewable and Sustainable Energy Reviews

199

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Section: Enhanced Oil and Gas Recoverymentioning

confidence: 99%

Flexible Carbon Capture and Utilization technologies in future energy systems and the utilization pathways of captured CO2

Mikulčić

Skov

Dominković

et al. 2019

Renewable and Sustainable Energy Reviews

199

View full text Add to dashboard Cite

show abstract

“…First, expanders have been used to replace the expansion valves and recover power from the expansion process 2 – 4 . Many studies indicated that the turbine expanders can recover energy to reduce the irreversibility of the expansion process 5 – 7 , but they are mechanically complicated and expensive 8 , 9 .…”

Section: Introductionmentioning

confidence: 99%

A unified approach for the thermodynamic comparison of heat pump cycles

Yu,

Ouderji

2023

Commun Eng

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The flexible heat pump cycle introduces a heat storage device into the Evans-Perkins cycle to recover, store, and reuse part of the sensible heat carried by the hot liquid refrigerant from the condenser, achieving a higher coefficient of performance than the latter. In this paper, we develop a unified approach, namely cycle superposition to allow comparison of the flexible heat pump cycle with other performance-enhancing cycle layouts including two-stage cycles with intercooling, subcooling, flash gas removal, or their combinations. We show that under ideal conditions, the flexible heat pump cycle is thermodynamically similar to two-stage heat pump cycles with full subcooling or flash gas removal, but no intercooling. From the energy recovery perspective, the two-stage cycles recover and reuse some sensible heat carried by hot liquid refrigerant simultaneously using their high-stage compressor, whereas the flexible heat pump cycle decouples the recovery and reuse of such heat in time using a heat storage. However, the irreversible heat transfer via real heat exchangers during charging and discharging processes will reduce the benefits of the flexible heat pump cycle. The effectiveness of all these performance-enhancing methods strongly depends on the characteristics of refrigerants.

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“…They indicated that increasing the efficiency of the IHX was beneficial for improving the system performance factor, the irreversible losses of the throttle valve were reduced by 40.36~50.73%, and the total system irreversible losses were reduced by 2.74~8.24%. Ghazizade et al [22] analyzed in depth the effect of the expander and the IHX on the exergy efficiency. They showed that the use of an IHX in a CO 2 transcritical cycle with an expansion valve always leads to an increase in the system COP and exergy efficiencies.…”

Section: Introductionmentioning

confidence: 99%

Exergy Analysis of Transcritical CO2 Air-Source Heat Pump with Honeycomb Gas Cooler

Zhang,

Wang,

Zhang

et al. 2023

Buildings

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In order to build an efficient and energy-saving CO2 heat pump system and to improve the heat transfer efficiency of the gas cooler, a novel honeycomb gas cooler with a compact structure, high heat transfer efficiency, and high pressure-bearing capacity was proposed in our previous work. To clarify the components in the system that need further optimization and to improve its performance, an exergy analysis of a transcritical CO2 air-source heat pump system with the novel honeycomb gas cooler is studied in this paper. Based on the second law of thermodynamics, the exergy model of each component in the heat pump system is established, and the irreversible loss of each component is analyzed. In addition, the degree of energy loss of the honeycomb gas cooler is clarified, and the possibility and direction of system optimization are pointed out. The results show that the exergy efficiency of the system is 35.33% under nominal operating conditions, and there is a lot of room for improvement in its energy utilization. The three components with the largest exergy destruction percentage are the compressor, throttle valve, and evaporator in the order of 36.13%, 22.90%, and 19.51%, respectively. These components with high exergy destruction percentages are the main reasons for the large irreversible losses of the system.

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Effects of using expander and internal heat exchanger on carbon dioxide direct-expansion geothermal heat pump

Cited by 28 publications

References 35 publications

Flexible Carbon Capture and Utilization technologies in future energy systems and the utilization pathways of captured CO2

Flexible Carbon Capture and Utilization technologies in future energy systems and the utilization pathways of captured CO2

A unified approach for the thermodynamic comparison of heat pump cycles

Exergy Analysis of Transcritical CO2 Air-Source Heat Pump with Honeycomb Gas Cooler

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