braking resistor of hybrid electric armored vehicle

Abstract-In the present paper, the heat transfer process of the braking resistor is analyzed. The corresponding theoretic model is proposed and solved numerically. The standard laminar model and constant heat flux method are employed to compute the heat transfer in the parallel channels between the braking resistor strips. The numerical computations for different conditions are performed. The corresponding heat transfer relationships among the convective heat transfer coefficient, thermal boundary layer thickness, cooling air outlet temperature and braking resistor surface temperature are studied according to the computed results. Finally, the theoretical heat transfer model of flow in the braking resistor case is used to investigate the variety of the resistor temperature of the practical braking resistor applied in some type hybrid electric armored vehicle. The vehicle operating test result shows that the uncertainty of the theoretic calculation model is within 15%, which can fulfill the engineering design requirement. Keywords- Braking Resistor; Heat Transfer; Hybrid Electric Armored Vehicle

 1. INTRODUCTION 

Compared to traditional vehicle, the regenerative braking of hybrid electric vehicle is a mainly trait. Regenerative braking is a kind of braking process in which the inertial energy generating from vehicle running is passed to the motor by transmission system and then the motor working as a generator uses the electric energy to charge the batteries, as seen in Fig. 1. In this process, the braking energy is used efficiently, which could decrease the energy consuming and increase the fuel saving. In the present study of hybrid electric vehicle technology, regenerative braking becomes an effective method to increase energy saving and continuous operating mileages. In the high intensity braking or continuous braking process, the electric energy recycled can not be fully absorbed because of the capability limitation of the energy storing components such as batteries. Under this circumstance, the braking resistor should be applied to consume the surplus energy in order to assure the safety and reliability of vehicle, as seen in Fig. 1. There are many rigorous operating conditions such as high speed braking, long slope continuous braking and so on in the hybrid electric armored vehicle (HEA V). So much higher requirement on safety and reliability is proposed for the components in HEAV.

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