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Dr.  Mohsen  Motahari-Nezhad
Technical and Vocational University,  Iran

Title: Studying the Transient Thermal Contact Conductance Between the Exhaust Valve and Its Seat Using the Inverse Method


In this study, the experiments aimed at analyzing thermally the exhaust valve in an air-cooled internal combustion engine and estimating the thermal contact conductance in fixed and periodic contacts. Due to the nature of internal combustion engines, the duration of contact between the valve and its seat is too short, and much time is needed to reach the quasi-steady state in the periodic contact between the exhaust valve and its seat. Using the methods of linear extrapolation and the inverse solution, the surface contact temperatures and the fixed and periodic thermal contact conductance were calculated. The results of linear extrapolation and inverse methods have similar trends, and based on the error analysis, they are accurate enough to estimate the thermal contact conductance. Moreover, due to the error analysis, a linear extrapolation method using inverse ratio is preferred. The effects of pressure, contact frequency, heat flux, and cooling air speed on thermal contact conductance have been investigated. The results show that by increasing the contact pressure the thermal contact conductance increases substantially. In addition, by increasing the engine speed the thermal contact conductance decreases. On the other hand, by boosting the air speed the thermal contact conductance increases, and by raising the heat flux the thermal contact conductance reduces. The average calculated error equals to 12.9 %.


Dr. Mohsen Motahari-Nezhad Specializes in the Heat transfer, Condition monitoring, Machine fault diagnosis, Acoustic emission, Experimental and numerical methods, Machine learning and Artificial neural networks in industry, academia, and government research. He obtained his Bachelor of Science degree from the University of Sistan and Baluchestan, Master’s degree from Iran University of Science and Technology, and his Ph.D from Shahid Beheshti University, Iran; all in Mechanical Engineering. He is currently a faculty member at Technical and Vocational University, Iran. Since 2022, he has been the dean of the Technical and Vocational University, Zabol branch. Prior to his current position, he worked at the Mapna Locomotive Company, Iran, analyzing the stability and control of the proposed noise attenuation systems. He also worked at the Iran Khodro Powertrain company investigating acoustic emission based fault diagnosis models. As a result of scientific research he has published more than 30 papers in peer-reviewed SCI and SCI-e Journals and reputed international conferences, also he has owned two patents with Hirsch index 7, and 225 citations. He is also an active reviewer of various SCI indexed journals.

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