A Simple Design Approach of Two-Phase Ejectors for CO2 Transcritical Heat Pumps
Integrating a two-phase ejector in mechanical vapor compression heat pumps is a practical and low-cost solution for improving performance and reducing energy consumption. Typically, using an ejector to recover part of the important pressure expansion losses in CO2 systems may improve the operating c...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Isfahan University of Technology
2023-07-01
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| Series: | Journal of Applied Fluid Mechanics |
| Subjects: | |
| Online Access: | https://www.jafmonline.net/article_2274_5ff6b31103eadbf27282bb68620ccc49.pdf |
| _version_ | 1827875200808517632 |
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| author | K. Ameur Z. Aidoun |
| author_facet | K. Ameur Z. Aidoun |
| author_sort | K. Ameur |
| collection | DOAJ |
| description | Integrating a two-phase ejector in mechanical vapor compression heat pumps is a practical and low-cost solution for improving performance and reducing energy consumption. Typically, using an ejector to recover part of the important pressure expansion losses in CO2 systems may improve the operating conditions of the compressor. One of the prerequisites for the success of such an application is the proper design of the ejector. This study is mainly dedicated to developing a simple approach for CO2 ejector design. The advantage of using the ejector as an expander in a transcritical CO2 heat pump is first introduced. Compressor operation is particularly improved. The development of an ejector design model for CO2 expanding from transcritical to two-phase conditions is presented. Validation of the thermodynamic model with experimental results from the literature shows the predictions to be within an acceptable range of discrepancy. The primary nozzle throat diameter calculations do not exceed ±8% of error for transcritical conditions. The error of the predicted pressure at the outlet of the ejector is in the limit of -15% to +3%. A practical design example for estimating the transcritical CO2 ejectors geometry integrated in a heat pump is presented. The results show the important decrease of primary nozzle diameters with the drop of Tevap, especially for the throat. A decrease of Dmix also occurs with Tevap and an optimal diameter is obtained for each condition considered. The design of the diffuser is based on a compromise between the outlet velocity and the length of the diffuser. The detailed design procedure with the proposed model, complemented with data from the literature, is a valuable tool for rapidly generating useful results and obtaining preliminary designs transcritical CO2 ejector. |
| first_indexed | 2024-03-12T17:03:26Z |
| format | Article |
| id | doaj.art-f0cf51d9e97841fbae42b596eca78ae2 |
| institution | Directory Open Access Journal |
| issn | 1735-3572 1735-3645 |
| language | English |
| last_indexed | 2024-03-12T17:03:26Z |
| publishDate | 2023-07-01 |
| publisher | Isfahan University of Technology |
| record_format | Article |
| series | Journal of Applied Fluid Mechanics |
| spelling | doaj.art-f0cf51d9e97841fbae42b596eca78ae22023-08-07T09:20:26ZengIsfahan University of TechnologyJournal of Applied Fluid Mechanics1735-35721735-36452023-07-0116101887190010.47176/jafm.16.10.18332274A Simple Design Approach of Two-Phase Ejectors for CO2 Transcritical Heat PumpsK. Ameur0Z. Aidoun1CanmetENERGY, Natural Resources Canada, Varennes, Qc, J3X1S6, CanadaCanmetENERGY, Natural Resources Canada, Varennes, Qc, J3X1S6, CanadaIntegrating a two-phase ejector in mechanical vapor compression heat pumps is a practical and low-cost solution for improving performance and reducing energy consumption. Typically, using an ejector to recover part of the important pressure expansion losses in CO2 systems may improve the operating conditions of the compressor. One of the prerequisites for the success of such an application is the proper design of the ejector. This study is mainly dedicated to developing a simple approach for CO2 ejector design. The advantage of using the ejector as an expander in a transcritical CO2 heat pump is first introduced. Compressor operation is particularly improved. The development of an ejector design model for CO2 expanding from transcritical to two-phase conditions is presented. Validation of the thermodynamic model with experimental results from the literature shows the predictions to be within an acceptable range of discrepancy. The primary nozzle throat diameter calculations do not exceed ±8% of error for transcritical conditions. The error of the predicted pressure at the outlet of the ejector is in the limit of -15% to +3%. A practical design example for estimating the transcritical CO2 ejectors geometry integrated in a heat pump is presented. The results show the important decrease of primary nozzle diameters with the drop of Tevap, especially for the throat. A decrease of Dmix also occurs with Tevap and an optimal diameter is obtained for each condition considered. The design of the diffuser is based on a compromise between the outlet velocity and the length of the diffuser. The detailed design procedure with the proposed model, complemented with data from the literature, is a valuable tool for rapidly generating useful results and obtaining preliminary designs transcritical CO2 ejector.https://www.jafmonline.net/article_2274_5ff6b31103eadbf27282bb68620ccc49.pdfco2 transcriticalejector designexpansion-work recoveryheat pump |
| spellingShingle | K. Ameur Z. Aidoun A Simple Design Approach of Two-Phase Ejectors for CO2 Transcritical Heat Pumps Journal of Applied Fluid Mechanics co2 transcritical ejector design expansion-work recovery heat pump |
| title | A Simple Design Approach of Two-Phase Ejectors for CO2 Transcritical Heat Pumps |
| title_full | A Simple Design Approach of Two-Phase Ejectors for CO2 Transcritical Heat Pumps |
| title_fullStr | A Simple Design Approach of Two-Phase Ejectors for CO2 Transcritical Heat Pumps |
| title_full_unstemmed | A Simple Design Approach of Two-Phase Ejectors for CO2 Transcritical Heat Pumps |
| title_short | A Simple Design Approach of Two-Phase Ejectors for CO2 Transcritical Heat Pumps |
| title_sort | simple design approach of two phase ejectors for co2 transcritical heat pumps |
| topic | co2 transcritical ejector design expansion-work recovery heat pump |
| url | https://www.jafmonline.net/article_2274_5ff6b31103eadbf27282bb68620ccc49.pdf |
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