EFFECT OF CONTACT PRESSURE AND FREQUENCY ON CONTACT HEAT TRANSFER BETWEEN EXHAUST VALVE AND ITS SEAT

The hot gases produced by the internal combustion engines passes through the exhaust valve and causes high temperatures in the exhaust valve and its seat. to avoid damaging the exhaust valve, heat must be transferred from the valve to its seat during the contact they make at the opening and closing cycle. heat transfer rate from the exhaust valve to its seat is a function of many factors. one of the most important factors is the thermal contact conductance (tcc) between the exhaust valve and its seat. very few researches have been done about estimation of the tcc between the exhaust valve and its seat in the past. an experimental study has been conducted to determine the tcc between two co-axial cylinders, as the exhaust valve and its seat. furthermore, the influence of contact pressure and frequency of contact upon the tcc is studied. the results show that the tcc decreases as the frequency of contact increases. the experimental results obtained from the present work are in good agreement with the previous published data.