Performance Investigation of Transcritical Carbon Dioxide Refrigeration Cycle

Baheta, Aklilu Tesfamichael; Hassan, Suhaimi; Reduan, Allya Radzihan B.; Woldeyohannes, Abraham Debebe

doi:10.1016/j.procir.2015.02.084

Cited by 23 publications

(5 citation statements)

References 3 publications

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“…Some thermal properties obtained through a quantitative analysis are summarized in Table . The addition of nano‐CuO into UHMWPE reduces melting point of the matrix slightly, which might be attributed to higher thermal conductivity of the filled CuO than the pristine UHMWPE . The results are consistent with TG analysis shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

In situ fabrication of CuO/UHMWPE nanocomposites and their tribological performance

Cao

Shi

Yan

et al. 2019

J of Applied Polymer Sci

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Polymer nanocomposites present remarkably enhanced mechanical and tribological properties with respect to their matrices even at a low loading of nanofillers. Here, cupric oxide (CuO) nanoparticles (nano-CuO) were in situ filled into ultra-high-molecularweight polyethylene (UHMWPE) to inhibit a possible agglomeration encountered in the preparation by mechanical mixing. The filled CuO nanoparticles were highly dispersed in UHMWPE with a reliable interface combination. The CuO nanoparticles in the matrix play a role for heterogeneous nucleation, resulting in an enhancement in degree of crystallinity of UHMWPE. The elastic modulus and the elongation at break of the nanocomposites also presented an improvement, indicating a good compatibility between the nano-CuO and the matrix. The average sliding friction coefficient of UHMWPE against 45 # steel was reduced by up to 34% after the in situ filling of CuO nanoparticles, and the wear mechanism was found to transform from adhesive to fatigue wear after the introduction of nano-CuO. It is concluded that the in situ filling can improve the dispersion of CuO nanoparticles in UHMWPE, and markedly promote the mechanical properties and tribological performance of UHMWPE.

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Section: Resultsmentioning

confidence: 99%

In situ fabrication of CuO/UHMWPE nanocomposites and their tribological performance

Cao

Shi

Yan

et al. 2019

J of Applied Polymer Sci

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“…The reason for the enhancement in the thermal conductivity for the composites nanouids may be attributed to its smaller size of the nanoparticles. The previous studies 24,50 showed that the thermal conductivity enhancement of the nanouid reduces as the particle size increases. In other words, the nanoparticles with smaller size should have higher thermal conductivity in the nanouids.…”

Section: Thermal Conductivity Of the Oxide Nanouidsmentioning

confidence: 94%

Investigation of optical absorption and photothermal conversion characteristics of binary CuO/ZnO nanofluids

2017

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“…The COP of a refrigeration cycle is given by the ratio between the extracted heat in the evaporation unit and the amount of work inverted in the compression stage . In addition, it is known that there is an optimum value of the COP depending on the ratio of compression ,− in a simple transcritical cycle. Then, considering a single-stage transcritical cycle with an efficiency, η, for the adiabatic compressor unit, and using the terminology shown in Figure for each stage of the cycle, the COP of the process is given by where H̃ i is the molar enthalpy at point i , and the superscript r concerns with the reversible approximation of the outlet of the adiabatic compressor unit.…”

Section: Results and Discussionmentioning

confidence: 99%

Accurate and Model-Free Control Function for a Single Stage Transcritical Refrigerator Cycle

et al. 2020

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Transcritical cycles are a successful and probed system in engineering practices, particularly in refrigeration. Therefore, their optimization is a critical factor in the design, control, and operation in order to maximize the coefficient of performance (COP) and to find the optimal pressure operating conditions. Often, this labor is faced using empirically based correlations, which are limited by their origin and the configuration of the cycle. In this regard, this work is devoted to the development of a rigorous and general framework in order to characterize the behavior and performance of a simple transcritical refrigeration cycle. An accurate mathematical expression for the COP depending on the compressor efficiency and the properties of the working fluid is presented. The expression proposed has no approximations and is relevant to any model depending on the Helmholtz variable group, being easy to combine with any equation of state (EOS), regardless of its complexity. From this expression, it is possible to derive a simple control function for transcritical refrigeration cycles. As an example, the expression is combined with the Span–Wagner EOS, presenting a comprehensive application for a transcritical cycle using CO 2 and N 2 O as working fluids.

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Performance Investigation of Transcritical Carbon Dioxide Refrigeration Cycle

Cited by 23 publications

References 3 publications

In situ fabrication of CuO/UHMWPE nanocomposites and their tribological performance

In situ fabrication of CuO/UHMWPE nanocomposites and their tribological performance

Investigation of optical absorption and photothermal conversion characteristics of binary CuO/ZnO nanofluids

Accurate and Model-Free Control Function for a Single Stage Transcritical Refrigerator Cycle

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