Effect of Interaction between Oil Additive Elements on the Heat Dissipated from Oil-Cooled Engine Parts at Various Wall Temperatures

Engine oils have complex packages of additives aimed at improving their tribological properties. However, interactions between elements of these additives may hinder the cooling ability of these oils. The current article addresses the influence of the interaction between chemical elements of oil additives on the cooling capacity of oils for different wall superheats (0°C-150°C) and oil bulk temperatures (60°C, 100°C, and 150°C). A back-propagation neural network (BPNN) is used to conduct the present work. The NN is trained on experimental heat transfer data of five commercial engine oils. Enhancement intensity, interaction sensitivity, and interaction stability of additive elements are investigated for the range of element concentrations of the experimental dataset. The results show that, for a given element concentration, the interaction between all elements causes dissimilar heat flux enhancement/deterioration for different oils and also affects the behavior of oils at different wall superheats and bulk temperatures. Some additive elements such as sodium, molybdenum, and boron are effective, sensitive, and stable to thermal interaction with other elements in oils, whereas calcium is the least sensitive element. Statistical analysis shows that some elements are less stable than others. In particular, silicon and phosphorous might change their effects from thermally antagonistic to synergetic elements.