Hollow Direct Air-Cooled Rotor Windings: Conjugate Heat Transfer Analysis
This article focuses on the analysis of a direct air-cooled rotor winding of a wound field synchronous machine, the innovation of which lies in the increase in the internal cooling surface, the cooling of the winding compared to the conventional inter-pole cooling, and the development of a CHT evalu...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
|
| Series: | Machines |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2075-1702/13/2/89 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850231476202766336 |
|---|---|
| author | Avo Reinap Samuel Estenlund Conny Högmark |
| author_facet | Avo Reinap Samuel Estenlund Conny Högmark |
| author_sort | Avo Reinap |
| collection | DOAJ |
| description | This article focuses on the analysis of a direct air-cooled rotor winding of a wound field synchronous machine, the innovation of which lies in the increase in the internal cooling surface, the cooling of the winding compared to the conventional inter-pole cooling, and the development of a CHT evaluation model accordingly. Conjugate heat transfer (CHT) analysis is used to explore the cooling efficacy of a parallel-cooled hollow-conductor winding of a salient-pole rotor and to identify a cooling performance map. The use of high current densities of 15–20 Arms/mm<sup>2</sup> in directly cooled windings requires high cooling intensity, which in the case of air cooling results not only in flow velocities above 15 m/s to ensure permissible operating temperatures, but also the need for coolant distribution and heat transfer studies. The experiments and calculations are based on a non-rotating machine and a wind tunnel using the same rotor coil(s). CHT-based thermal calculations provide not only reliable results compared to experimental work and lumped parameter thermal circuits with adjusted aggregate parameters, but also insight related to pressure and cooling flow distribution, thermal loads, and cooling integration issues that are necessary for the development of high power density and reliable electrical machines. The results of the air-cooling integration show that the desired high current density is achievable at the expense of high cooling intensity, where the air velocity ranges from 15 to 30 m/s and 30 to 55 m/s, distinguishing the air velocity of the hollow conductor and bypass channel, compared to the same coil in an electric machine and a wind tunnel at the similar thermal load and limit. Since the hot spot location depends on cooling integration and cooling intensity, modeling and estimating the cooling flow is essential in the development of wound-field synchronous machines. |
| format | Article |
| id | doaj-art-4a67e1bf7f6546c892a561dec046b2c5 |
| institution | OA Journals |
| issn | 2075-1702 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Machines |
| spelling | doaj-art-4a67e1bf7f6546c892a561dec046b2c52025-08-20T02:03:31ZengMDPI AGMachines2075-17022025-01-011328910.3390/machines13020089Hollow Direct Air-Cooled Rotor Windings: Conjugate Heat Transfer AnalysisAvo Reinap0Samuel Estenlund1Conny Högmark2Division of Industrial Electrical Engineering and Automation, Lund University, 221 00 Lund, SwedenDivision of Industrial Electrical Engineering and Automation, Lund University, 221 00 Lund, SwedenDivision of Industrial Electrical Engineering and Automation, Lund University, 221 00 Lund, SwedenThis article focuses on the analysis of a direct air-cooled rotor winding of a wound field synchronous machine, the innovation of which lies in the increase in the internal cooling surface, the cooling of the winding compared to the conventional inter-pole cooling, and the development of a CHT evaluation model accordingly. Conjugate heat transfer (CHT) analysis is used to explore the cooling efficacy of a parallel-cooled hollow-conductor winding of a salient-pole rotor and to identify a cooling performance map. The use of high current densities of 15–20 Arms/mm<sup>2</sup> in directly cooled windings requires high cooling intensity, which in the case of air cooling results not only in flow velocities above 15 m/s to ensure permissible operating temperatures, but also the need for coolant distribution and heat transfer studies. The experiments and calculations are based on a non-rotating machine and a wind tunnel using the same rotor coil(s). CHT-based thermal calculations provide not only reliable results compared to experimental work and lumped parameter thermal circuits with adjusted aggregate parameters, but also insight related to pressure and cooling flow distribution, thermal loads, and cooling integration issues that are necessary for the development of high power density and reliable electrical machines. The results of the air-cooling integration show that the desired high current density is achievable at the expense of high cooling intensity, where the air velocity ranges from 15 to 30 m/s and 30 to 55 m/s, distinguishing the air velocity of the hollow conductor and bypass channel, compared to the same coil in an electric machine and a wind tunnel at the similar thermal load and limit. Since the hot spot location depends on cooling integration and cooling intensity, modeling and estimating the cooling flow is essential in the development of wound-field synchronous machines.https://www.mdpi.com/2075-1702/13/2/89wound-field synchronous machinerotor windingscomputational fluid dynamicsair coolingexperimental testing |
| spellingShingle | Avo Reinap Samuel Estenlund Conny Högmark Hollow Direct Air-Cooled Rotor Windings: Conjugate Heat Transfer Analysis Machines wound-field synchronous machine rotor windings computational fluid dynamics air cooling experimental testing |
| title | Hollow Direct Air-Cooled Rotor Windings: Conjugate Heat Transfer Analysis |
| title_full | Hollow Direct Air-Cooled Rotor Windings: Conjugate Heat Transfer Analysis |
| title_fullStr | Hollow Direct Air-Cooled Rotor Windings: Conjugate Heat Transfer Analysis |
| title_full_unstemmed | Hollow Direct Air-Cooled Rotor Windings: Conjugate Heat Transfer Analysis |
| title_short | Hollow Direct Air-Cooled Rotor Windings: Conjugate Heat Transfer Analysis |
| title_sort | hollow direct air cooled rotor windings conjugate heat transfer analysis |
| topic | wound-field synchronous machine rotor windings computational fluid dynamics air cooling experimental testing |
| url | https://www.mdpi.com/2075-1702/13/2/89 |
| work_keys_str_mv | AT avoreinap hollowdirectaircooledrotorwindingsconjugateheattransferanalysis AT samuelestenlund hollowdirectaircooledrotorwindingsconjugateheattransferanalysis AT connyhogmark hollowdirectaircooledrotorwindingsconjugateheattransferanalysis |