{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T04:08:50Z","timestamp":1776830930265,"version":"3.51.2"},"reference-count":13,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2025,9,15]],"date-time":"2025-09-15T00:00:00Z","timestamp":1757894400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Computation"],"abstract":"<jats:p>This paper presents a study aiming to provide insight into the complex flow and heat transfer processes in the exhaust manifold of a four-stroke, compression ignition engine. An experimental system has been constructed capable of capturing temperature and heat flux high-frequency signals as they develop in the exhaust pipe wall during the engine cycle, under its steady-state operation. The values of the Heat Transfer Coefficient obtained by applying the classic convection relations have been correlated in the form of a Nusselt\u2013Reynolds number relationship for local and spatially averaged steady-state heat transfer and compared with available experimental data obtained at the same position of the exhaust manifold. It has been shown that the use of conventional steady-state heat transfer relationships for fully developed steady-state turbulent flow in pipes underpredicts heat transfer rates when compared with those experimentally observed. Periodic flow of high frequency and geometrical effects at the exhaust entrance are expected to affect the validity of the application of the classic steady-state correlations for the exhaust manifold. To overcome this problem it is developed and presented a new correlation for the time-averaged heat transfer rates. To verify the heat transfer mechanism, the thermal field of the whole engine cylinder head, including the intake and exhaust manifolds, was analyzed using FEA (Finite Element Analysis), and the results are compared and verified with available experimental data.<\/jats:p>","DOI":"10.3390\/computation13090223","type":"journal-article","created":{"date-parts":[[2025,9,15]],"date-time":"2025-09-15T09:43:41Z","timestamp":1757929421000},"page":"223","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Heat Losses in the Exhaust Manifold of a 4-Stoke DI Diesel Engine Subjected to Pulsating Flow"],"prefix":"10.3390","volume":"13","author":[{"given":"Grigorios","family":"Spyrounakos","sequence":"first","affiliation":[{"name":"Mechanical Engineering Department, University of West Attica, Thivon & P. Ralli Ave. 250, 12241 Aigaleo, Greece"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5429-8971","authenticated-orcid":false,"given":"Georgios","family":"Mavropoulos","sequence":"additional","affiliation":[{"name":"Internal Combustion Engines and Automotive Technology Laboratory, Department of Mechanical Engineering Educators, School of Pedagogical and Technological Education (ASPETE), 15122 Marousi, Greece"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Wendland, D.W. (1993). Automobile Exhaust-System Steady-State Heat Transfer. 1993 Vehicle Thermal Management Systems Conference Proceedings (VTMS1), SAE. SAE Paper 931085.","DOI":"10.4271\/931085"},{"key":"ref_2","unstructured":"Malchow, G.L., Sorenson, S.C., and Buckius, R.O. (March, January 26). Heat Transfer in the Straight Section of an Exhaust Port of a Spark Ignition Engine. Proceedings of the SAE Automotive Engineering Congress and Exposition, Detroit, MI, USA. SAE Paper 790309."},{"key":"ref_3","first-page":"565","article-title":"Cycle-averaged heat flux measurements in a straight-pipe extension of the exhaust port of a SI engine","volume":"115","author":"Farrugia","year":"2006","journal-title":"SAE Trans. J. Engines"},{"key":"ref_4","first-page":"673","article-title":"Analysis and Modeling of Heat Transfer in the SI Engine Exhaust System During Warm-Up","volume":"116","author":"Heller","year":"2007","journal-title":"SAE Trans. J. Engines"},{"key":"ref_5","first-page":"652","article-title":"Instantaneous Exhaust Temperature Measurements Using Thermocouple Compensation Techniques","volume":"113","author":"Kar","year":"2004","journal-title":"SAE Trans. J. Fuels Lubr.-V113-4"},{"key":"ref_6","first-page":"734","article-title":"A Universal Heat Transfer Correlation for Intake and Exhaust Flows in an Spark-Ignition Internal Combustion Engine","volume":"111","author":"Depcik","year":"2002","journal-title":"SAE Trans. J. Engines"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Ranganathan, R.P., Turner, D.W., and Franchett, M.E. (2005, January 11\u201314). Exhaust Manifold Gas Temperature Predictions using System Level Data Driven Modelling. Proceedings of the SAE 2005 World Congress & Exhibition, Detroit, MI, USA. SAE Paper 2005-01-0698, 2005.","DOI":"10.4271\/2005-01-0698"},{"key":"ref_8","first-page":"1154","article-title":"Steady-State Local Heat Flux Measurements in a Straight Pipe Extension of an Exhaust Port of a Spark Ignition Engine","volume":"116","author":"Balzan","year":"2007","journal-title":"SAE Trans. J. Engines"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"847","DOI":"10.4271\/2013-01-0879","article-title":"The Development of Exhaust Surface Temperature Models for 3D CFD Vehicle Thermal Management Simulations Part 1-General Exhaust Configurations","volume":"6","author":"Haehndel","year":"2013","journal-title":"SAE Int. J. Passeng. Cars-Mech. Syst."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1547","DOI":"10.4271\/2014-01-1711","article-title":"Study on the Unsteady Heat Transfer of Engine Exhaust Manifold Based on the Analysis Method of Serial","volume":"7","author":"Zhien","year":"2014","journal-title":"SAE Int. J. Engines"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"888","DOI":"10.4271\/2008-01-1326","article-title":"Experimental Assessment of Instantaneous Heat Transfer in the Combustion Chamber and Exhaust Manifold Walls of Air-Cooled Direct Injection Diesel Engine","volume":"1","author":"Mavropoulos","year":"2008","journal-title":"SAE Int. J. Engines"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Mavropoulos, G.C., and Hountalas, D.T. (2013, January 16\u201318). Exhaust Phases in a DI Diesel Engine Based on Instantaneous Cyclic Heat Transfer Experimental Data. Proceedings of the SAE 2013 World Congress & Exhibition, Detroit, MI, USA. SAE Paper 2013-01-1646.","DOI":"10.4271\/2013-01-1646"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Rakopoulos, C.D., Mavropoulos, G.C., and Hountalas, D.T. (1998, January 23\u201326). Modeling the Structural Thermal Response of an Air-Cooled Diesel Engine under Transient Operation Including a Detailed Thermodynamic Description of Boundary Conditions. Proceedings of the SAE 1998 International Congress and Exposition, Detroit, MI, USA. SAE Paper 981024.","DOI":"10.4271\/981024"}],"container-title":["Computation"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-3197\/13\/9\/223\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:45:34Z","timestamp":1760035534000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-3197\/13\/9\/223"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,15]]},"references-count":13,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2025,9]]}},"alternative-id":["computation13090223"],"URL":"https:\/\/doi.org\/10.3390\/computation13090223","relation":{},"ISSN":["2079-3197"],"issn-type":[{"value":"2079-3197","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,9,15]]}}}