Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 55 5 2023 07 23 Determination of convective heat transfer coefficient in human femur bone drilling in the presence of normal saline and evaluation of effective parameters Determination of convective heat transfer coefficient in human femur bone drilling in the presence of normal saline and evaluation of effective parameters 557 576 5146 10.22060/mej.2023.20586.7273 FA Shirzad Sadri Mechanical Engineering Group/ Department of Engineering/University of Zanjan/Zanjan/Iran Jalal Ghasemi Mechanical Engineering Group/ Department of Engineering/ University of Zanjan/ Znajan/Iran Journal Article 2021 09 30 This research has analyzed the drilling process in the human femur bone to determine the heat transfer coefficient and occurrence or non-occurrence of thermal necrosis. 3D drilling simulation has carried out naturally with air and force convection with normal-saline and the analysis was performed for three feed rates of 50, 100, and 150 millimeters per minute(mm/min) at speeds of 500, 1000, and 2000 rotation per minute(rpm). The results show that in natural cooling, the highest generated heat is equal to 4 Joule at 50mm/min and 500rpm while the lowest value of generated heat is 1.65 Joule at 150mm/min and 2000rpm. The maximum difference of the average heat transfer coefficient with the experimental results is 12.5%, which represents a good accuracy of the present results. The results also show that the average heat transfer coefficient at 100 and 150mm/min is 55% and 29.1% more, respectively, and it is 5% less at 50mm/min compared to the constant value of 20  w/ m² k, which is considered in the previous researches. Also, thermal necrosis occurs under all conditions of natural cooling. In  forced cooling, the highest average heat transfer coefficient with normal-saline is 150mm/min at a speed of 2000rpm, which is equal to 3650 w/ m² k, and in all conditions, the bone temperature has not exceeded the temperature limit of thermal necrosis. This research has analyzed the drilling process in the human femur bone to determine the heat transfer coefficient and occurrence or non-occurrence of thermal necrosis. 3D drilling simulation has carried out naturally with air and force convection with normal-saline and the analysis was performed for three feed rates of 50, 100, and 150 millimeters per minute(mm/min) at speeds of 500, 1000, and 2000 rotation per minute(rpm). The results show that in natural cooling, the highest generated heat is equal to 4 Joule at 50mm/min and 500rpm while the lowest value of generated heat is 1.65 Joule at 150mm/min and 2000rpm. The maximum difference of the average heat transfer coefficient with the experimental results is 12.5%, which represents a good accuracy of the present results. The results also show that the average heat transfer coefficient at 100 and 150mm/min is 55% and 29.1% more, respectively, and it is 5% less at 50mm/min compared to the constant value of 20  w/ m² k, which is considered in the previous researches. Also, thermal necrosis occurs under all conditions of natural cooling. In  forced cooling, the highest average heat transfer coefficient with normal-saline is 150mm/min at a speed of 2000rpm, which is equal to 3650 w/ m² k, and in all conditions, the bone temperature has not exceeded the temperature limit of thermal necrosis. https://mej.aut.ac.ir/article_5146_717729ce391c20ef3e722c3e6ef79a58.pdf