Condensation of an Azeotropic Mixture inside 2.5 mm ID Minitubes
The ongoing miniaturization of air conditioning and refrigeration systems, in order to limit, as much as possible, the refrigerant charge, calls for smaller and smaller heat exchangers. Besides, the new environmental regulations are calling for new pure refrigerants or refrigerants mixtures with low...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-10-01
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| Series: | Fluids |
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| Online Access: | https://www.mdpi.com/2311-5521/5/4/171 |
| _version_ | 1827704957226188800 |
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| author | Andrea Diani Luisa Rossetto |
| author_facet | Andrea Diani Luisa Rossetto |
| author_sort | Andrea Diani |
| collection | DOAJ |
| description | The ongoing miniaturization of air conditioning and refrigeration systems, in order to limit, as much as possible, the refrigerant charge, calls for smaller and smaller heat exchangers. Besides, the new environmental regulations are calling for new pure refrigerants or refrigerants mixtures with lower values of global warming potentials (GWPs). In this context, this paper analyzes the possible implementation of minitubes during condensation of the azeotropic mixture R513A. Two minitubes are tested: a smooth tube with an inner diameter of 2.5 mm, and a microfin tube with an inner diameter at the fin tip of 2.4 mm. The effects of vapor quality (varied in the range 0.10–0.99), of mass velocity (varied in the range 200–1000 kg m<sup>−2</sup> s<sup>−1</sup>), and of saturation temperature (30 °C and 40 °C) on the heat transfer coefficient are investigated. The experimental results indicate that the heat transfer coefficient increases as both vapor quality and mass velocity increase, both in the case of the smooth tube and of the microfin tube, but the slope of the heat transfer coefficient trend respect to vapor quality is higher in the case of the microfin tube. The microfin tube shows, on average, heat transfer coefficients are 79% higher than those of the smooth tube under the same working conditions. Since R513A is a possible substitute of R134a, some experimental data during condensation heat transfer are also compared against those for R134a. Finally, the experimental results are compared against values estimated by empirical correlations available in the open literature. |
| first_indexed | 2024-03-10T15:52:33Z |
| format | Article |
| id | doaj.art-222973e1ed4341d8909afe9b55e69a23 |
| institution | Directory Open Access Journal |
| issn | 2311-5521 |
| language | English |
| last_indexed | 2024-03-10T15:52:33Z |
| publishDate | 2020-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Fluids |
| spelling | doaj.art-222973e1ed4341d8909afe9b55e69a232023-11-20T15:55:08ZengMDPI AGFluids2311-55212020-10-015417110.3390/fluids5040171Condensation of an Azeotropic Mixture inside 2.5 mm ID MinitubesAndrea Diani0Luisa Rossetto1Department of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, ItalyDepartment of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, ItalyThe ongoing miniaturization of air conditioning and refrigeration systems, in order to limit, as much as possible, the refrigerant charge, calls for smaller and smaller heat exchangers. Besides, the new environmental regulations are calling for new pure refrigerants or refrigerants mixtures with lower values of global warming potentials (GWPs). In this context, this paper analyzes the possible implementation of minitubes during condensation of the azeotropic mixture R513A. Two minitubes are tested: a smooth tube with an inner diameter of 2.5 mm, and a microfin tube with an inner diameter at the fin tip of 2.4 mm. The effects of vapor quality (varied in the range 0.10–0.99), of mass velocity (varied in the range 200–1000 kg m<sup>−2</sup> s<sup>−1</sup>), and of saturation temperature (30 °C and 40 °C) on the heat transfer coefficient are investigated. The experimental results indicate that the heat transfer coefficient increases as both vapor quality and mass velocity increase, both in the case of the smooth tube and of the microfin tube, but the slope of the heat transfer coefficient trend respect to vapor quality is higher in the case of the microfin tube. The microfin tube shows, on average, heat transfer coefficients are 79% higher than those of the smooth tube under the same working conditions. Since R513A is a possible substitute of R134a, some experimental data during condensation heat transfer are also compared against those for R134a. Finally, the experimental results are compared against values estimated by empirical correlations available in the open literature.https://www.mdpi.com/2311-5521/5/4/171condensationR513Aheat transfer coefficientsmooth tubemicrofin tube |
| spellingShingle | Andrea Diani Luisa Rossetto Condensation of an Azeotropic Mixture inside 2.5 mm ID Minitubes Fluids condensation R513A heat transfer coefficient smooth tube microfin tube |
| title | Condensation of an Azeotropic Mixture inside 2.5 mm ID Minitubes |
| title_full | Condensation of an Azeotropic Mixture inside 2.5 mm ID Minitubes |
| title_fullStr | Condensation of an Azeotropic Mixture inside 2.5 mm ID Minitubes |
| title_full_unstemmed | Condensation of an Azeotropic Mixture inside 2.5 mm ID Minitubes |
| title_short | Condensation of an Azeotropic Mixture inside 2.5 mm ID Minitubes |
| title_sort | condensation of an azeotropic mixture inside 2 5 mm id minitubes |
| topic | condensation R513A heat transfer coefficient smooth tube microfin tube |
| url | https://www.mdpi.com/2311-5521/5/4/171 |
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