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Performance enhancement of a vapor compression refrigeration system using R134a/MWCNT-oil mixture and liquid-suction heat exchanger equipped with twisted tape turbulator

International Journal of Refrigeration • 2020
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Publication Information
Authors Mohamed R. Salem
Keywords Vapor compression refrigeration system; MWCNT/oil Nanolubricant; Liquid suction heat exchanger; Twisted tape turbulator; Coefficient of performance
Journal International Journal of Refrigeration
Publisher Elsevier Masson SAS
Volume 120
Issue Not Available
Pages 357-369
publication.type International
Paper Link Open Link
Supplementary Materials Not Available
Abstract
This study investigates the performance attributes of a vapor compression refrigeration system (VCRS) with employing R134a/MWCNT-oil mixture and liquid-suction heat exchanger (LSHE) with/without twisted tape turbulator (TTT). The tests are done at different cycle pressure ratios (6.55-10.12), TTT twist ratios (1 ≤ λ ≤ 4), and nanoparticles’ mass concentrations (0 ≤ φ ≤ 0.5%). The experiments state that the exergy destruction rates are reduced by employing LSHE, TTT with reducing its twist ratio, and engaging R134a/MWCNT-oil mixture with increasing the MWCNTs loading, besides growing the cycle pressure ratio. Compared to the simple VCRS, the maximum enhancements in the COP and exergy efficiency (ηEx) of the VCRS are 37.3% and 126.5%, respectively, while compared to the simple LSHE, its effectiveness is improved by 97.9% obtained by simultaneously applying LSHE with TTT of λ = 1 and R134a/MWCNT-oil mixture of φ = 0.5%. Correlations are supplied to predict the COP and ηEx of the VCRS besides the effectiveness of LSHE.