Theoretical analysis and experimental research on transcritical CO2 two stage compression cycle with two gas coolers (TSCC+TG) and the cycle with intercooler (TSCC+IC)

Wang, Hongli; Ma, Yixin; Tian, Jingrui; Li, Minxia

doi:10.1016/j.enconman.2011.02.003

Cited by 41 publications

(11 citation statements)

References 12 publications

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“…It can also be noticed from Figures 8 and 9 that the percentage improvement in the case of the DCFI cycle is higher than that in a DCEI cycle under all the chosen operating conditions. This tendency is consistent with the experimental results of [10] where the COP of DCFI cycle is 19.0% higher than that of DCEI cycle. The reason may be that the lower optimum gas cooler pressure of the DCFI cycle makes the pressure ratios of both compressors lower, resulting in higher compressor isentropic efficiency values.…”

Section: Resultssupporting

confidence: 82%

“…It can also be noticed from Figures 6 and 7 that the optimum gas cooler pressure and the intermediate pressure of the DCFI cycle are lower than those of the DCEI cycle under various operating conditions. This tendency is consistent with the experimental results of [10] where the optimum gas cooler pressure and the intermediate pressure of the DCFI cycle are 0.2 MPa and 0.3 MPa lower than that of the DCEI cycle. It is always preferred to operate the system at lower gas cooler pressure.…”

Section: Resultssupporting

confidence: 81%

“…Cho et al [9] numerically found that the single-stage CO2 cycle with an expander, the double-stage external intercooler cycle, and the double-stage CO2 cycle with vapor injection yield 28.3%, 13.1%, 18.3% improvements of the cooling COP over that of the basic CO2 cycle, respectively. Wang et al [10] carried out an experiment on the two-stage compression cycle using R744 as a refrigerant, and showed that the COP of the double-stage flash intercooler cycle is 10.97% higher than that of the double-stage external intercooler cycle.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic Analysis of Double-Stage Compression Transcritical CO2 Refrigeration Cycles with an Expander

Zhang¹,

Tong²,

Wang³

2015

Entropy

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Four different double-compression CO2 transcritical refrigeration cycles are studied: double-compression external intercooler cycle (DCEI), double-compression external intercooler cycle with an expander (DCEIE), double-compression flash intercooler cycle (DCFI), double-compression flash intercooler cycle with an expander (DCFIE). The results showed that the optimum gas cooler pressure and optimum intermediate pressure of the flash intercooler cycles are lower than that of the external intercooler cycle. The use of an expander in the DCEI cycle leads to a decrease of the optimum gas cooler pressure and little variation of the optimum intermediate pressure. However, the replacement of the throttle valve with an expander in the DCFI cycle results in little variation of the optimal gas cooler pressure and an increase of the optimum intermediate pressure. The DCFI cycle outperforms the DCEI cycle under all the chosen operating conditions. The DCEIE cycle outperforms the DCFIE cycle when the evaporating temperature exceeds 0 °C or the gas cooler outlet temperature surpasses 35 °C. When the gas cooler exit temperature varies from 32 °C to 48 °C, the DCEI cycle, DCEIE cycle, DCFI cycle and DCFIE cycle yield averaged 4.6%, 29.2%, 12.9% and 22.3% COP improvement, respectively, over the basic cycle.

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Section: Resultssupporting

confidence: 82%

Section: Resultssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

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Thermodynamic Analysis of Double-Stage Compression Transcritical CO2 Refrigeration Cycles with an Expander

Zhang¹,

Tong²,

Wang³

2015

Entropy

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“…In the compression process, the big head of connecting rod withstands the upward pulling force by the crankshaft, and the small head withstands the downward differential pressure by the piston. In the discharge process, the big head withstands downward pulling force by the crankshaft and the small head withstands upward differential pressure by the piston, the differential pressure distribution was shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Numerical simulation of CO₂ piston compressor in transcritical compression cycle

Wang

Tian

et al. 2016

Env Prog and Sustain Energy

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Based on theory of thermodynamics and kinetics, the mathematical model of crank connecting rod of a CO2 piston compressor was established and the stress deformations were employed by ANSYS finite element software. In the compression process, when the differential pressure is 4 and 5 MPa, the maximal displacement variation, stress variation, and strain variation are 18.79 μm, 12.8 MPa, and 0.28 × 10−3. When the differential pressure is 6 and 7 MPa, the maximal displacement variation, stress variation, and strain variation are 26.30 μm, 18.0 MPa, and 0.39 × 10−3. In the discharge process, when the differential pressure is 4 and 5 MPa, the maximal displacement variation, stress variation, and strain variation are 19.43 μm, 27.7 MPa, and 0.615 × 10−3. When the differential pressure is 6 and 7 MPa, the maximal displacement variation, stress variation, and strain variations are 27.20 μm, 48.4 MPa, and 1.08 × 10−3. No matter the compression process or the discharge process, the maximal displacement deformation, the maximal stress variation or the maximal strain variation are mainly concentrated in the small head of crank connecting rod, and small head is also more likely to damage. The higher differential pressure causes the crank connecting rod to product a bigger stress variation and displacement variation. Under the same conditions, the connecting rod in discharge process has a bigger displacement variation than the compression process, so the small head of crank connecting rod in discharge process is more easily to be broken. Some fundamental data were obtained for improving the efficiency of CO2 piston compressor and developing the products of CO2 refrigeration air condition and heat pumps. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1772–1783, 2016

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“…[11][12][13][14] For large or middle power compressors, one of the most important ways to save energy is using multistage compression and intercooling. [15][16][17][18][19] The air compressed part ways to the discharge pressure, passed through an intercooler, and then compressed further. To minimize specific work input or power consumption, in two-stage air compression with 100% isentropic efficiency and 100% intercooler effectiveness, is readily seen to require that the stage pressure ratio rise should be the square root of overall pressure ratio in the more restrictive perfect gas model.…”

Section: Introductionmentioning

confidence: 99%

Modeling and optimization of industrial multistage compressed air system using actual variable effectiveness in hot regions

Azizifar

Banooni

2016

Advances in Mechanical Engineering

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In this article, modeling and optimization of power consumption of two-stage compressed air system have been investigated. To do so, the two-stage compressed air cycle with intercooler of Fajr Petrochemical Company was considered. This cycle includes two centrifugal compressors, a shell, and a tube intercooler. For modeling of power consumption, isentropic efficiencies of actual compressors and thermal effectiveness of intercooler are calculated from experimental data. In these equations, isentropic efficiency of compressors is a function of the inlet temperature, and thermal effectiveness of the intercooler is a function of the inlet air temperature, inlet water temperature of the intercooler, and inlet volumetric flow rate of the cycle. For optimization of power consumption, the Lagrangian method is used. Power consumption and isentropic efficiency of the first-and second-stage compressors, thermal effectiveness of the intercooler, and entropy generation of compressors are considered as the objective function and optimization conditions, respectively. In comparison with the experimental data, the modeling provided suitable accuracy. The optimization effectively reduced the power consumption of the cycle, especially in summer, in a way that the minimum and maximum reductions were 2.9% and 9.6%, respectively.

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Theoretical analysis and experimental research on transcritical CO2 two stage compression cycle with two gas coolers (TSCC+TG) and the cycle with intercooler (TSCC+IC)

Cited by 41 publications

References 12 publications

Thermodynamic Analysis of Double-Stage Compression Transcritical CO2 Refrigeration Cycles with an Expander

Thermodynamic Analysis of Double-Stage Compression Transcritical CO2 Refrigeration Cycles with an Expander

Numerical simulation of CO₂ piston compressor in transcritical compression cycle

Modeling and optimization of industrial multistage compressed air system using actual variable effectiveness in hot regions

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Theoretical analysis and experimental research on transcritical CO2 two stage compression cycle with two gas coolers (TSCC+TG) and the cycle with intercooler (TSCC+IC)

Cited by 41 publications

References 12 publications

Thermodynamic Analysis of Double-Stage Compression Transcritical CO2 Refrigeration Cycles with an Expander

Thermodynamic Analysis of Double-Stage Compression Transcritical CO2 Refrigeration Cycles with an Expander

Numerical simulation of CO2 piston compressor in transcritical compression cycle

Modeling and optimization of industrial multistage compressed air system using actual variable effectiveness in hot regions

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Product

Resources

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Numerical simulation of CO₂ piston compressor in transcritical compression cycle