Theoretical and experimental studies on optimum heat rejection pressure for a CO2 heat pump system

Zhang, X.P.; Fan, Xiaomeng; Wang, F.K.; Shen, Hua

doi:10.1016/j.applthermaleng.2010.07.003

Cited by 50 publications

(16 citation statements)

References 16 publications

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“…Similar work was done by Zhang, Fan, Wang and Shen [19] and a different correction to Liao, Zhao and Jakobsen [9] was proposed.…”

Section: Subscriptsmentioning

confidence: 61%

“…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: 96%

“…p opt ¼ 0:119T 0:887 amb À 28:437R 2 ba À 8:09R ba þ 1:178ε 2 SHX À 0:844ε SHX À 4:772R ba ε SHX þ 33:82 (18) where R ba is the coefficient ratio of high-temperature compressor, ε SHX is the effectiveness of suction line heat exchanger. Sarkar [22] optimized an ejector-expansion transcritical CO 2 heat pump cycle and proposed p opt ¼ 22:7 þ 0:21T e þ 1:06T c À 0:0094T e T c þ 0:0213T 2 c (19) where, À45 C < T e < 5 C, 30 C < T c < 60 C.…”

Section: Subscriptsmentioning

confidence: 99%

See 2 more Smart Citations

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

Liu

Cai

et al. 2015

Applied Thermal Engineering

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“…Similar work was done by Zhang, Fan, Wang and Shen [19] and a different correction to Liao, Zhao and Jakobsen [9] was proposed.…”

Section: Subscriptsmentioning

confidence: 61%

Section: Literature Cycle Description Equations Statisticsmentioning

confidence: 96%

Section: Subscriptsmentioning

confidence: 99%

See 1 more Smart Citation

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

Liu

Cai

et al. 2015

Applied Thermal Engineering

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“…Based on the previous researches on pure R744 heat pump by our research group, R744/R290 mixture is proposed as a potential alternative refrigerant used in heat pump systems for water heating and space heating [7]. Then it is essential to confirm which composition of mixture is optimum, or at least appropriate, for the certain heat pump application.…”

Section: Introduction mentioning

confidence: 99%

Simulation Study on a Heat Pump System Using R744/R290 as Refrigerant

Fan¹,

Zhang²,

Wang³

2013

JCEA

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Based on the Chinese National Standards involving heat pump water heater and space heating system, performances of the R744/R290 subcritical heat pump system have been discussed and compared with those of the R22 system, which is widely used in heat pump systems in China nowadays. It can be indicated that R744/R290 mixture can work efficiently as a refrigerant for heat pumps with a large heat-sink temperature rise. When mass fraction of R290 is increased, discharge pressure is reduced. Under the nominal working condition, there is an optimum mixture mass fraction of 20/80 for R744/R290 under conventional condensation pressure. Both the heating COP hs (coefficient of performance) and volumetric heating capacity are increased by about 12.62% and 34.24% respectively compared with those of R22 based system. But for the heat sink with a small temperature rise, R744/R290 system has poorer performances than R22 system. When heat transfer pinch point in evaporator and condensation processes is considered, the degree of superheat has a negative influence upon system performances under the given conditions.

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“…The unique The optimal discharge pressure is one of the research hotspots in the trans-critical CO2 systems. In recent years, many theoretical analysis and experimental investigations were carried out on this topic [2][3][4][5][6][7][8][9][10][11], and some stressed on the optimal discharge pressure control [12][13][14]. However, most of these studies focused on the operating conditions when the CO2 temperature at the gas-cooler outlet is above the critical temperature.…”

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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Theoretical and experimental studies on optimum heat rejection pressure for a CO2 heat pump system

Cited by 50 publications

References 16 publications

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

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

Simulation Study on a Heat Pump System Using R744/R290 as Refrigerant

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

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