In internal combustion engines, exhaust valve and its seat gain considerable temperature as the hot gases exit through them. So, the rate of heat transfer should be under control. In this study, the contact heat transfer coefficient has been estimated. An experimental study on an Air-Cooled internal combustion engine cylinder head has been considered. Using the measured temperatures of sensors located in specific locations of the exhaust valve and the seat and the method of linear extrapolation, the surface contact temperatures and constant and periodic contact heat transfer coefficient were calculated. Also, a sensitivity analysis has been done to study the effects of different parameters of contact pressure, contact frequency, heat flux and cooling air speed on thermal contact conductance. The results show that between the major four considered parameters, the thermal contact conductance is more sensitive to the contact pressure, then the contact frequency, heat flux and the cooling air speed are the most affecting parameters on thermal contact resistance.

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