Search

The evolution of automotive electrical system architecture in commercial and military applications is discussed in this paper. The present voltage levels of 14 volt in commercial and generally 28 volt in military vehicles are unable to sustain the growing demands of electrical loads, created largely due to the advent of power electronics. In this paper the issue of transitioning to 42 volt system is discussed. Presently 42 volt system is finding its headway in the commercial automotive industry. A large number of papers have discussed the pros and cons of 42 volts systems for commercial vehicles. However, there still remain some significant issues which need to be examined very carefully in order to have 42 volt systems transitioned to military vehicles. In military applications, 42 volt system issues have ramifications towards cost and technical advantages. The paper discusses these issues, with the commercial manufacturing infra-structure in perspective. In addition, other electrical system architectures besides the 42 volt system are introduced as a prelude to their possible introduction in future military vehicles.

An analysis of film condensation on a vertical fluted tube has been made considering gravitational and surface tension effects over the entire fluted surface, and using surface-oriented coordinates. For the first time surface tension effects are determined, as they should, from the shape of the condensate-vapor interface rather than the shape of the flute. Two-dimensional conduction within the condensate film as well as in the fluted tube is considered. A finite-difference solution of the highly non-linear partial differential equation for the film thickness is coupled with a finite-element solution of the condition problem. The procedure has been tested on a sinusoidal flute with amplitude to pitch ratio approx. 0.2. A linear extrapolation, on a log-log basis, of our results shows good comparison with experimental data.