{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,4]],"date-time":"2025-11-04T10:57:09Z","timestamp":1762253829998,"version":"build-2065373602"},"reference-count":31,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2021,6,18]],"date-time":"2021-06-18T00:00:00Z","timestamp":1623974400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100008530","name":"European Regional Development Fund","doi-asserted-by":"publisher","award":["No.1.1.1.2\/VIAA\/3\/19\/501"],"award-info":[{"award-number":["No.1.1.1.2\/VIAA\/3\/19\/501"]}],"id":[{"id":"10.13039\/501100008530","id-type":"DOI","asserted-by":"publisher"}]},{"name":"European Regional Development Fund (ERDF)","award":["POCI-01-0145-FEDER-029494"],"award-info":[{"award-number":["POCI-01-0145-FEDER-029494"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Machines"],"abstract":"<jats:p>This paper presents the analytical calculation of the heat transfer coefficient of a complex housing shape of a Totally Enclosed Fan-Cooled (TEFC) industrial machine when it works below 20% of its nominal speed or close to stall. Therefore, passive cooling is dominant, and most of the heat is extracted by the combination of natural convection and radiation phenomena. Under these conditions, the area-based composite approach was used for the development of the analytical calculation method. A test rig using a TEFC Synchronous Reluctance Motor (SynRM) was constructed, and the collected experimental data was used to validate the proposed analytical method successfully.<\/jats:p>","DOI":"10.3390\/machines9060120","type":"journal-article","created":{"date-parts":[[2021,6,18]],"date-time":"2021-06-18T04:10:47Z","timestamp":1623989447000},"page":"120","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Determination of Heat Transfer Coefficient from Housing Surface of a Totally Enclosed Fan-Cooled Machine during Passive Cooling"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6917-5883","authenticated-orcid":false,"given":"Payam","family":"Shams Ghahfarokhi","sequence":"first","affiliation":[{"name":"Department of Electrical Machines and Apparatus, Riga Technical University, Ka\u013c\u0137u iela 1, LV-1658 Riga, Latvia"},{"name":"Department of Electrical Power Engineering and Mechatronics, Tallinn University of Technology, 19086 Tallinn, Estonia"},{"name":"CISE\u2014Electromechatronic Systems Research Centre, University of Beira Interior, P 6201-001 Covilh\u00e3, Portugal"}]},{"given":"Andrejs","family":"Podgornovs","sequence":"additional","affiliation":[{"name":"Department of Electrical Machines and Apparatus, Riga Technical University, Ka\u013c\u0137u iela 1, LV-1658 Riga, Latvia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6126-1878","authenticated-orcid":false,"given":"Ants","family":"Kallaste","sequence":"additional","affiliation":[{"name":"Department of Electrical Power Engineering and Mechatronics, Tallinn University of Technology, 19086 Tallinn, Estonia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8737-6999","authenticated-orcid":false,"given":"Antonio J. Marques","family":"Cardoso","sequence":"additional","affiliation":[{"name":"CISE\u2014Electromechatronic Systems Research Centre, University of Beira Interior, P 6201-001 Covilh\u00e3, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2154-8692","authenticated-orcid":false,"given":"Anouar","family":"Belahcen","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering and Automation, Aalto University, P.O. Box 15500, 00076 Aalto, Finland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0481-5066","authenticated-orcid":false,"given":"Toomas","family":"Vaimann","sequence":"additional","affiliation":[{"name":"Department of Electrical Power Engineering and Mechatronics, Tallinn University of Technology, 19086 Tallinn, Estonia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9474-2659","authenticated-orcid":false,"given":"Bilal","family":"Asad","sequence":"additional","affiliation":[{"name":"Department of Electrical Power Engineering and Mechatronics, Tallinn University of Technology, 19086 Tallinn, Estonia"},{"name":"Department of Electrical Engineering and Automation, Aalto University, P.O. Box 15500, 00076 Aalto, Finland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6751-9099","authenticated-orcid":false,"given":"Hans","family":"Tiismus","sequence":"additional","affiliation":[{"name":"Department of Electrical Power Engineering and Mechatronics, Tallinn University of Technology, 19086 Tallinn, Estonia"}]}],"member":"1968","published-online":{"date-parts":[[2021,6,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"3509","DOI":"10.1109\/TIE.2008.922604","article-title":"Convection Heat Transfer and Flow Calculations Suitable for Electric Machines Thermal Models","volume":"55","author":"Staton","year":"2008","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1150","DOI":"10.1109\/TIA.2008.926233","article-title":"Determination of Critical Parameters in Electrical Machine Thermal Models","volume":"44","author":"Boglietti","year":"2008","journal-title":"IEEE Trans. Ind. Appl."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Shams Ghahfarokhi, P., Kallaste, A., Vaimann, T., and Belahcen, A. (2019, January 14\u201317). Thermal Analysis of Totally Enclosed Fan Cooled Synchronous Reluctance Motor-state of art. Proceedings of the 45th Annual Conference of the IEEE Industrial Electronics Society (IECON), Lisbon, Portugal. Available online: https:\/\/ieeexplore.ieee.org\/document\/8927706.","DOI":"10.1109\/IECON.2019.8927706"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1828","DOI":"10.1049\/iet-epa.2020.0237","article-title":"Development of analytical thermal analysis tool for synchronous reluctance motors","volume":"14","author":"Ghahfarokhi","year":"2020","journal-title":"IET Electr. Power Appl."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Rosu, M., Zhou, P., Lin, D., Ionel, D., Popescu, M., Blaabjerg, F., Rallabandi, V., and Staton, D. (2018). Multiphysics Simulation by Design for Electrical Machines, Power Electronics, and Drives, Wiley.","DOI":"10.1002\/9781119103462"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Popescu, M., Staton, D., Dorrell, D., Marignetti, F., and Hawkins, D. (2013, January 11\u201312). Study of the thermal aspects in brushless permanent magnet machines performance. Proceedings of the 2013 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD), Paris, France.","DOI":"10.1109\/WEMDCD.2013.6525165"},{"key":"ref_7","unstructured":"Miller, T.J.E. (1993). Switched Reluctance Motors and Their Control, Oxford University Press."},{"key":"ref_8","unstructured":"Staton, D.A., and So, E. (1998, January 12\u201315). Determination of optimal thermal parameters for brushless permanent magnet motor design. Proceedings of the Conference Record of 1998 IEEE Industry Applications Conference. Thirty-Third IAS Annual Meeting, St. Louis, MO, USA."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1049\/ip-b.1991.0025","article-title":"Lumped parameter thermal model for electrical machines of TEFC design","volume":"138","author":"Mellor","year":"1991","journal-title":"IEE Proc. B Electr. Power Appl."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"945","DOI":"10.1109\/TIA.2003.814555","article-title":"A simplified thermal model for variable-speed self-cooled industrial induction motor","volume":"39","author":"Boglietti","year":"2003","journal-title":"IEEE Trans. Ind. Appl."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"871","DOI":"10.1109\/TIE.2008.2011622","article-title":"Evolution and Modern Approaches for Thermal Analysis of Electrical Machines","volume":"56","author":"Boglietti","year":"2009","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"620","DOI":"10.1109\/TEC.2005.847979","article-title":"Solving the More Difficult Aspects of Electric Motor Thermal Analysis in Small and Medium Size Industrial Induction Motors","volume":"20","author":"Staton","year":"2005","journal-title":"IEEE Trans. Energy Convers."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"688","DOI":"10.1109\/TIA.2006.873655","article-title":"Evaluation of radiation thermal resistances in industrial motors","volume":"42","author":"Boglietti","year":"2006","journal-title":"IEEE Trans. Ind. Appl."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Boglietti, A., and Vallan, A. (2006, January 24\u201327). Measurement of Housing Thermal Resistances in Industrial Motors. Proceedings of the IEEE Instrumentation and Measurement Technology Conference, Sorrento, Italy.","DOI":"10.1109\/IMTC.2006.328522"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"3379","DOI":"10.1016\/j.ijheatmasstransfer.2006.03.010","article-title":"Heat transfer from a horizontal fin array by natural convection and radiation\u2014A conjugate analysis","volume":"49","author":"Rao","year":"2006","journal-title":"Int. J. Heat Mass Transf."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1016\/j.ijthermalsci.2014.03.016","article-title":"Natural convection from rectangular interrupted fins","volume":"82","author":"Ahmadi","year":"2014","journal-title":"Int. J. Therm. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1681","DOI":"10.1109\/TIE.2018.2835397","article-title":"Cooling of Automotive Traction Motors: Schemes, Examples, and Computation Methods","volume":"66","author":"Gai","year":"2019","journal-title":"IEEE Trans. Ind. Electron."},{"key":"ref_18","unstructured":"Cengel, Y.A. (2004). Heat Transfer: A Practical Approach, McGraw-Hill."},{"key":"ref_19","unstructured":"Bejan, A., and Kraus, A.D. (2003). Heat Transfer Handbook, John Wiley & Sons."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Shams Ghahfarokhi, P., Kallaste, A., Vaimann, T., and Belahcen, A. (2018, January 16\u201318). Natural convection from flat side\u2019s of coil system. Proceedings of the 19th International Scientific Conference on Electric Power Engineering (EPE), Brno, Czech Republic.","DOI":"10.1109\/EPE.2018.8395967"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"6","DOI":"10.1115\/1.3449648","article-title":"Optimum Arrangement of Rectangular Fins on Horizontal Surfaces for Free-Convection Heat Transfer","volume":"92","author":"Jones","year":"1970","journal-title":"J. Heat Transf."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"677","DOI":"10.1016\/j.ijheatmasstransfer.2018.05.071","article-title":"Determination of natural convection heat transfer coefficient over the fin side of a coil system","volume":"126","author":"Kallaste","year":"2018","journal-title":"Int. J. Heat Mass Transf."},{"key":"ref_23","unstructured":"(2021, June 17). Motor-CAD Software by Motor Design\u2014EMag, Therm and Lab. Available online: https:\/\/www.motor-design.com\/motor-cad-software\/."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Pyrhonen, J., Jokinen, T., and Hrabovcova\u0301, V. (2008). Design of Rotating Electrical Machines, Wiley.","DOI":"10.1002\/9780470740095"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2167","DOI":"10.1109\/TIA.2016.2518132","article-title":"Modern Heat Extraction Systems for Power Traction Machines\u2014A Review","volume":"52","author":"Popescu","year":"2016","journal-title":"IEEE Trans. Ind. Appl."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Markovic, M., Saunders, L., and Perriard, Y. (2006, January 8\u201312). Determination of the Thermal Convection Coefficient for a Small Electric Motor. Proceedings of the Conference Record of the 2006 IEEE Industry Applications Conference Forty-First IAS Annual Meeting, Tampa, FL, USA.","DOI":"10.1109\/IAS.2006.256520"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Meksi, O., and Vargas, A.O. (2015, January 20\u201324). Numerical and experimental determination of external heat transfer coefficient in small TENV electric machines. Proceedings of the 2015 IEEE Energy Conversion Congress and Exposition (ECCE), Montreal, QC, Canada.","DOI":"10.1109\/ECCE.2015.7310044"},{"key":"ref_28","first-page":"1","article-title":"Determination of heat transfer coefficient of finned housing of a TEFC variable speed motor","volume":"103","author":"Kallaste","year":"2020","journal-title":"Electr. Eng."},{"key":"ref_29","unstructured":"Boglietti, A., Cavagnino, A., and Staton, D.A. (2003, January 12\u201316). Thermal analysis of TEFC induction motors. Proceedings of the 38th IAS Annual Meeting on Conference Record of the Industry Applications Conference, Salt Lake City, UT, USA."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"756","DOI":"10.1109\/TIA.2005.847311","article-title":"TEFC Induction Motors Thermal Models: A Parameter Sensitivity Analysis","volume":"41","author":"Boglietti","year":"2005","journal-title":"IEEE Trans. Ind. Appl."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Shams Ghahfarokhi, P., Kallaste, A., Vaimann, T., Rassolkin, A., and Belahcen, A. (2019, January 12\u201313). Steady-State Thermal Model of a Synchronous Reluctance Motor. Proceedings of the 2018 IEEE 59th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON), Riga, Latvia.","DOI":"10.1109\/RTUCON.2018.8659846"}],"container-title":["Machines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-1702\/9\/6\/120\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:18:05Z","timestamp":1760163485000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-1702\/9\/6\/120"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,6,18]]},"references-count":31,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2021,6]]}},"alternative-id":["machines9060120"],"URL":"https:\/\/doi.org\/10.3390\/machines9060120","relation":{},"ISSN":["2075-1702"],"issn-type":[{"type":"electronic","value":"2075-1702"}],"subject":[],"published":{"date-parts":[[2021,6,18]]}}}