Thermodynamic performance assessment of carbon dioxide blends with low-global warming potential (GWP) working fluids for a heat pump water heater

Dai, Baomin; Dang, Chaobin; Li, Minxia; Tian, Hua; Ma, Yixin

doi:10.1016/j.ijrefrig.2014.11.009

Cited by 102 publications

(34 citation statements)

References 24 publications

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“…After an initial screening, nine refrigerants were selected as candidates (listed in Table ) . The selection is mainly based on suitable thermodynamic properties and environment friendly properties: appropriate critical temperature to ensure the cycle operating in subcritical state, as transcritical and supercritical cycles were not in the scope of this study. evaporation pressure higher than 0.1 MPa and condensation pressure lower than 2.5 MPa to make components work effectively and stably. preference to zero ozone depletion potential (ODP) then low global warming potential (GWP) (less than 300) or safety. …”

Section: Refrigerant Selectionmentioning

confidence: 99%

“…After an initial screening, nine refrigerants were selected as candidates (listed in Table 5). [27][28][29] The selection is mainly based on suitable thermodynamic properties and environment friendly properties:…”

Section: Parameters In Heat Pump Cyclementioning

confidence: 99%

“…2. evaporation pressure higher than 0.1 MPa and condensation pressure lower than 2.5 MPa to make components work effectively and stably. 3. preference to zero ozone depletion potential (ODP) then low global warming potential (GWP) (less than 300) 27 or safety.…”

Section: Parameters In Heat Pump Cyclementioning

confidence: 99%

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Thermodynamic analysis of novel heat pump cycles for drying process with large temperature lift

2019

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Summary Heat pump–assisted drying has been recognized a prospective technology to meet the requirement of energy saving. However, large temperature lift will be resulted by the single‐stage heat pump cycle during the high‐temperature drying, especially operating with low ambient temperature for open‐loop drying, which leads to insufficient heat output, high compression ratio, and low coefficient of performance (COP). Two heat pump cycles, namely, multitemperature cascade cycle and combined single‐stage cycle, are proposed to address the above problems in the drying process with large temperature lift in this paper. The effects of varying operation parameters on the heat pump cycles are analyzed to optimize the cycle performance. Afterwards, the above two cycles as well as a conventional cascade cycle, a two‐stage compression cycle, and a single‐stage compression cycle are compared with each other in terms of cycle performance and drying performance under specified drying conditions. It is indicated by the results that the COPs of the multitemperature cascade cycle and combined single‐stage cycle are about 95% and 88% higher than that of the single‐stage compression cycle, respectively. As for the two cascade cycles (ie, conventional cascade cycle and multitemperature cascade cycle), 49% more water evaporation with the same power input can be resulted by the added condenser and evaporator. Among the five analyzed cycles, the multitemperature cascade cycle is the most promising to be used in the retrofitting of the drying equipment with large temperature lift.

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Section: Refrigerant Selectionmentioning

confidence: 99%

Section: Parameters In Heat Pump Cyclementioning

confidence: 99%

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Thermodynamic analysis of novel heat pump cycles for drying process with large temperature lift

2019

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“…However, the CO 2 in the transcritical cycle will have great throttling loss and irreversibility, which is because the operating pressure on the high-pressure side is between 8 and 12 MPa. 15 This shortcoming limits the widespread use of CO 2 systems. Although the transcritical cycle overcomes the limitation of the early subcritical cycle of refrigeration capacity affected by the environment, the COP of the system remains low.…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of thermodynamic performance of CO ₂ cascade refrigeration system assisted with expander and mechanical subcooling

Sun

Wang

et al. 2019

Int J Energy Res

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Summary In order to discuss the feasibility of using R744/R744 cascade refrigeration system (CRS) instead of R744/R717 CRS, six configurations of R744/R744 CRS assisted with expander and mechanical subcooling system (MS) are analyzed. Based on the thermodynamic analysis, the results show that the high pressure, the condensing temperature of the low‐temperature cycle (LTC), and the degree of subcooling of LTC and the high‐temperature cycle (HTC) are three important operating parameters with an optimum value corresponding to the maximum coefficient of performance (COP). Compared with other CRSs, CRS with HTC throttling valve and MS of HTC (CTSH) and CRS with HTC expander and MS of HTC (CESH) show an excellent performance. CESH has the highest COP and is improved by an average of 13.8% compared with the COP of R744/R717 CRS. The COP of CTSH is improved by an average of 4.2% compared with the COP of R744/R717 CRS. In conclusion, it is an efficient way to improve performance that CRS combines MS in HTC and HTC expander. And it is possible R744/R744 CRS instead of R744/R717 CRS.

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“…Much effort has been devoted to the system performance evaluation [17][18][19][20] and many novel optimizing strategies have been proposed based on extensive theoretical analysis and experimental tests [13,21,22]. Some other studies examined the performance of the gas cooler [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Performance of Water Source Trans-Critical CO2 Heat Pump Water Heater

Liu

Zhang

et al. 2017

Energies

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Abstract:The effect of the discharge pressure on the performance of the trans-critical CO 2 heat pump with a low gas-cooler outlet temperature is experimentally investigated on a test rig of water source heat-pump water heater. The optimal discharge pressure of the trans-critical CO 2 heat pump is investigated under different external operation conditions. When the tap-water temperature is low, the characteristic of the S-shape isotherm at the supercritical region has little effect on the occurrence of the optimal discharge pressure; while the mass flow rate of CO 2 , the suction pressure and the gas-cooler outlet temperature play a significant role in determining the emergence of the optimal discharge pressure. At the optimal discharge pressure, the COP reaches the peak; however, the corresponding heating capacity is still lower than its maximum, which is reached as the discharge pressure is slightly above the optimal discharge pressure. Reducing the tap-water flowrate or increasing the water-source temperature can increase the optimal discharge pressure. The COP is positively dependent on both the tap-water flowrate and the water-source temperature. In addition, the tap-water flowrate has a negligible influence on the maximum heating capacity while increasing the water-source temperature can greatly enhance the heating capacity.

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Thermodynamic performance assessment of carbon dioxide blends with low-global warming potential (GWP) working fluids for a heat pump water heater

Cited by 102 publications

References 24 publications

Thermodynamic analysis of novel heat pump cycles for drying process with large temperature lift

Thermodynamic analysis of novel heat pump cycles for drying process with large temperature lift

Comparative analysis of thermodynamic performance of CO ₂ cascade refrigeration system assisted with expander and mechanical subcooling

Experimental Study on the Performance of Water Source Trans-Critical CO2 Heat Pump Water Heater

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Thermodynamic performance assessment of carbon dioxide blends with low-global warming potential (GWP) working fluids for a heat pump water heater

Cited by 102 publications

References 24 publications

Thermodynamic analysis of novel heat pump cycles for drying process with large temperature lift

Thermodynamic analysis of novel heat pump cycles for drying process with large temperature lift

Comparative analysis of thermodynamic performance of CO 2 cascade refrigeration system assisted with expander and mechanical subcooling

Experimental Study on the Performance of Water Source Trans-Critical CO2 Heat Pump Water Heater

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Comparative analysis of thermodynamic performance of CO ₂ cascade refrigeration system assisted with expander and mechanical subcooling