Improving thermal performance of hydrodynamic couplings through heat sink design with functionally graded fins

Hydrodynamic couplings help transfer power from electric motors to rotating equipment. The continuous operation of hydrodynamic couplings causes the temperature of the oil inside them to increase over time, degrading its properties. The performance of hydrodynamic couplings can be greatly improved by implementing an effective cooling system that significantly lowers the oil temperature. This paper proposes a new heat sink design for the external cooling of hydrodynamic couplings, using functionally graded materials with variable thickness fins. The first step is to derive an energy balance equation for the hydrodynamic coupling and determine the relationship between the temperature of the coupling’s oil and the heat loss from the heat sink. After that, a thermal differential equation is derived to analyze the proposed heat sink. Because hydrodynamic couplings operate rotationally, the convection coefficient is expressed as a function of temperature and location. The resulting differential equation has a high degree of nonlinearity. To solve this equation, a new analytical method called the differential transformation method is applied, with validation done using the finite element method. The analytical solution evaluates various parameters that affect the heat sink’s performance and the hydrodynamic coupling. The results show a significant decrease in oil temperature, improving the performance of the hydrodynamic coupling. The analytical model of the new heat sink allows appropriate designs to be selected for different couplings without needing numerical solutions.