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Advanced energy conversion technologies are being investigated by the Power Technology Division (PTD) of the NASA Lewis Research Center. Among the technologies are batteries, induction motors, high frequency electric power management and distribution, dynamic energy storage, and Stirling cycle machines. While the emphasis of the Division is the application of these technologies to fulfill space power requirements, many terrestrial applications exist. This paper presents a study assessing the feasibility of a hybrid electric vehicle based on some advanced technologies being investigated by the PTD. The study considers fuel economy, emissions, driveability, performance, and range of a mid-size, current production vehicle (Taurus) operating in the hybrid mode. A vehicle with a 20.1 kWe (27 hp) free-piston Stirling power convertor as the prime mover, and a flywheel as the energy storage device was modeled.

Advanced power technologies are being investigated by the Power Technology Division (PTD) of the NASA Lewis Research Center (LeRC). These technologies are varied and the applications are diverse. Among these technologies are batteries, high efficiency induction motors, high frequency electric power distribution, dynamic energy storage, and Stirling cycle machines. While the emphasis of the PTD research is the application of these technologies to fulfill space power requirements, terrestrial applications may also exist. Future regulation of vehicular emission levels has prompted a recent increase in interest in electric and hybrid vehicles. Electric vehicles have been limited in range and performance by the storage capability of currently available batteries. As an alternative, the hybrid vehicle may render a more near term solution to provide an environmentally safe, full performance vehicle.

Under the Department of Energy's (DoE) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for terrestrial Solar Distributed Heat Receivers. The Stirling engine has been identified by Sandia as one of the most promising heat engines for terrestrial applications. The Stirling engine has the potential to meet DoE's performance and cost goals [1]. The NASA Lewis Research Center is providing management of the Advanced Stirling Conversion System (ASCS) Project through an Interagency Agreement with the DoE. NASA Lewis is conducting technology development for Stirling convertors directed toward a dynamic power source for space applications. Space power requirements include high reliability with long life, high system efficiency and low vibration. The free-piston Stirling engine has the potential for both solar and nuclear space power applications.

The Stirling Powered Van Program (SPVP) is a multiyear, multiphase program to evaluate the automotive Stirling engine (ASE) in Air Force vans under realistic conditions. The objective of the SPVP is to have a manufacturer and end user(s) (i.e., on the path to commercialization) of the second-generation Mod II ASE upon completion of the Automotive Stirling Engine Program in 1987. In order to meet this objective, the SPVP must establish Stirling performance, integrity; reliability, durability, and maintainability. This paper reviews the ASE Program background leading to the Van Program and focuses on plans for evaluating the kinematic Stirling engine in Air Force vans. Also discussed are the NASA technology transfers to industry that have been accomplished and those which are currently being developed.