Thermal analysis of a novel retarder by using the nanofluid cooling system: Numerical and experimental approaches.

To solve the problem of braking torque decline or even brake failure of vehicle retarders caused by high temperature due to long‐time or high‐power braking, the nanofluid with high thermal conductivity is introduced into the previously proposed novel retarder. To evaluate the nanofluid cooling capabilities, a model depicting the vertical fluid flow in the retarder is formulated. Adopting similarity transformations and a shooting method coupled with Runge–Kutta iterative technology, the model boundary value problem is tackled numerically. The cooling capabilities of three typical ethylene glycol (EG)‐based nanofluids: Cu–EG, Al2O3–EG, and TiO2–EG are investigated and compared. Finally, an experimental test is carried out to examine the temperature rise and the variation of braking torque for the retarder. It is demonstrated that Al2O3–EG nanofluid has the highest Nusselt number (rate of heat transfer), and more importantly, the braking torque of the proposed retarder decreases by only 8.2% under high‐power braking condition. [ABSTRACT FROM AUTHOR]