Supersonic two-phase flow of CO2 through converging–diverging nozzles for the ejector refrigeration cycle |
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Authors: | Masafumi Nakagawa Menandro Serrano Berana Akinori Kishine |
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Affiliation: | aDepartment of Mechanical and Structural System Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi City, Aichi 441-8580, Japan;bDepartment of Mechanical Engineering, University of the Philippines, Diliman, Quezon City 1101, Philippines;cMachine Tool Division, Murata Machinery, Ltd., 2 Nakajima, Hashizume, Inuyama City, Aichi 484-8502, Japan |
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Abstract: | CO2 is environmentally friendly, safe and more suitable to ejector refrigeration cycle than to vapor compression cycle. Supersonic two-phase flow of CO2 in the diverging sections of rectangular converging–diverging nozzles was investigated. The divergence angles with significant variation of decompression were 0.076°, 0.153°, 0.306° and 0.612°. This paper presents experimental decompression phenomena which can be used in designing nozzles and an assessment of Isentropic Homogeneous Equilibrium (IHE). Inlet conditions around 6–9 MPa, 20–37 °C were used to resemble ejector nozzles of coolers and heat pumps. For inlet temperature around 37 °C, throat decompression boiling from the saturated liquid line, supersonic decompression and IHE solution were obtained for the two large divergence angles. For divergence angles larger than 0.306°, decompression curves for inlet temperature above 35 °C approached IHE curves. For divergence angles smaller than 0.306° or for nozzles with inlet temperature below 35 °C, IHE had no solution. |
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Keywords: | Refrigeration system Ejector system Carbon dioxide Experiment Two-phase flow Nozzle Parameter GeometryMots clé s: Systè me frigorifique Systè me à é jecteur Dioxyde de carbone Expé rimentation È coulement diphasique Tuyè re Paramè tre Gé omé trie |
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