Optimization of two-stage transcritical carbon dioxide heat pump cycles

Agrawal, Neeraj; Bhattacharyya, Souvik; Sarkar, Jahar

doi:10.1016/j.ijthermalsci.2006.04.011

Cited by 105 publications

(47 citation statements)

References 11 publications

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“…For this reason all tests were carried out maintaining an air velocity equal to 6 m s À1 . In the entire test the heat rejection pressure of the R744 is equal to the optimal value as fixed by the BPV [15,16]. To define the optimal heat rejection pressure values, the Liao et al's [17] correlation was considered.…”

Section: Resultsmentioning

confidence: 99%

Transcritical CO₂refrigerator and sub-critical R134a refrigerator: A comparison of the experimental results

Aprea

Maiorino

2009

Int. J. Energy Res.

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SUMMARYThis paper describes experiments comparing a commercial available R134a refrigeration plant subjected to a cold store and a prototype R744 (carbon dioxide) system working as a classical 'split-systems' to cool air in residential applications in a transcritical cycle. Both plants are able to develope a refrigeration power equal to 3000 W. The R744 system utilizes aluminium heat exchangers, a semi-hermetic compressor, a back-pressure valve and a thermostatic expansion valve. The R134a refrigeration plant operates using a semi-hermetic reciprocating compressor, an air condenser followed by a liquid receiver, a manifold with two expansion valves, a thermostatic one and a manual one mounted in parallel, and an air cooling evaporator inside the cold store. System performances are compared for two evaporation temperatures varying the temperature of the external air running over the gas-cooler and over the condenser. The refrigeration load in the cold store is simulated by means of some electrical resistances, whereas the air evaporator of the R744 plant is placed in a very large ambient. The results of the comparison are discussed in terms of temperature of the refrigerants at the compressor discharge line, of refrigerants mass flow rate and of coefficient of performance (COP). The performances measured in terms of COPs show a decrease with respect to the R134a plant working at the same external and internal conditions. Further improvements regarding the components of the cycle are necessary to use in a large-scale 'split-systems' working with the carbon dioxide.

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Section: Resultsmentioning

confidence: 99%

Transcritical CO₂refrigerator and sub-critical R134a refrigerator: A comparison of the experimental results

Aprea

Maiorino

2009

Int. J. Energy Res.

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“…Using the control volume to determine the amount of energy is done regardless of the kinetic energy and potential heat interaction in the system boundary, which is equal to total enthalpy. Relations related to the thermodynamic cycle of the analysis are as follows [17][18][19]: Figure 5 shows the effect of the internal heat exchanger use in single-stage and two-stage compression cycle on increasing the pressure of gas cooler function. As can be seen, two-stage transcritical cycle performance is higher than single-stage cycle.…”

Section: Statement Of the Problem And Numerical Simulationmentioning

confidence: 99%

Numerical analysis of transcritical carbon dioxide compression cycle: a case study

Keshtkar¹

2018

JACST

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This study deals with thermodynamic investigation of a refrigeration compression cycle with carbon dioxide refrigerant and two stage compression. In this paper, the effect of intercooler in the two-stage compression system at different pressures of gas cooler is investigated. In addition, the performance of one stage compression cycle and two-stage compression cycle are compared and eventually, the performance of system is investigated under the influence of the change of variables such as gas cooler pressure, isentropic efficiency of the compressors, the intercooling rate between the two stages of compression, the refrigerant gas cooler outlet temperature is examined. Due to evaporation temperature in the evaporator   C and refrigeration capacity (kW) results show that the coefficient of performance in the two-stage compression with intercooler is increased compared to the single-stage compression cycle.

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“…When 5 C T amb 35 C, p opt ¼ 10:97995 þ 1:06442T wo þ 1:01404T amb À 0:01216T 2 amb (12) where water outlet temperature T wo ranges from 55 C to 80 C. Agrawal, Bhattacharyya and Sarkar [12] proposed a two-stage transcritical carbon dioxide heat pump cycles. With flash gas bypass, they had p opt ¼ 25:11 À 0:087T e þ ð0:973 þ 0:019T c ÞT c (13) With flash intercooling, they got…”

Section: Subscriptsmentioning

confidence: 99%

“…Kauf [8] Single-stage valve-expansion (1) SD 5.8% for p opt Liao, Zhao and Jakobsen [9] Single-stage valve-expansion (2) SD 1% for p opt Sarkar, Bhattacharyya and Gopal [10] Single-stage valve-expansion (3) N/A Sarkar, Bhattacharyya and Gopal [23] Single-stage valve-expansion (4) R 2 ¼ 0.995 for p opt Chen and Gu [11] Single-stage valve-expansion (5) (6) SD ¼ 0.94% for p opt Kim, Won and Kim [17] Single-stage valve-expansion (7) N/A Aprea and Maiorino [18] Single-stage valve-expansion (8) More accurate than Liao, Zhao and Jakobsen [9] for specific experimental p opt ; Zhang, Fan, Wang and Shen [19] Single-stage valve-expansion (9) More accurate than Liao, Zhao and Jakobsen [9] for specific experimental p opt ; Qi, He, Wang and Meng [16] Single-stage valve-expansion (10) MaxD 5% for experimental p opt ; MaxD 6% for real system COP Wang, Tuo, Cao and Xing [20] Single-stage valve-expansion (11) (12) MaxD ¼ 5.5% for experimental p opt , corresponding COP loss 1.3% Agrawal, Bhattacharyya and Sarkar [12] Two-stage valve-expansion (13) [13] Single/two-stage valve-expansion (16) N/A Ge and Tassou [15] Supermarket boost system (17) N/A Ge and Tassou [14] Supermarket boost system (18) AD ¼ 0.45%, MaxD ¼ 1.89% for p opt Sarkar [22] Single-stage ejector-expansion (19) R 2 ¼ 0.999 for p opt Elbel and Hrnjak [27] Single-stage ejector-expansion (20) N/A Xu, Chen, Tang and Zhu [24] Single-stage ejector-expansion (21) N/A Yari [21] Two-stage ejector-expansion (22) R 2 ¼ 0.9998 for p opt Fig. 2.…”

Section: Literature Cycle Description Equations Statisticsmentioning

confidence: 99%

Minimizing COP loss from optimal high pressure correlation for transcritical CO2 cycle

Liu

Cai

et al. 2015

Applied Thermal Engineering

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Optimization of two-stage transcritical carbon dioxide heat pump cycles

Cited by 105 publications

References 11 publications

Transcritical CO₂refrigerator and sub-critical R134a refrigerator: A comparison of the experimental results

Transcritical CO₂refrigerator and sub-critical R134a refrigerator: A comparison of the experimental results

Numerical analysis of transcritical carbon dioxide compression cycle: a case study

Minimizing COP loss from optimal high pressure correlation for transcritical CO2 cycle

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Optimization of two-stage transcritical carbon dioxide heat pump cycles

Cited by 105 publications

References 11 publications

Transcritical CO2refrigerator and sub-critical R134a refrigerator: A comparison of the experimental results

Transcritical CO2refrigerator and sub-critical R134a refrigerator: A comparison of the experimental results

Numerical analysis of transcritical carbon dioxide compression cycle: a case study

Minimizing COP loss from optimal high pressure correlation for transcritical CO2 cycle

Contact Info

Product

Resources

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Transcritical CO₂refrigerator and sub-critical R134a refrigerator: A comparison of the experimental results

Transcritical CO₂refrigerator and sub-critical R134a refrigerator: A comparison of the experimental results