Abstract
In National Aerospace Laboratory (NAL), a conceptual model of life support system was designed. This is a self-contained partially circulated life support system, called the SEPAL. The most significant feature of the SEPAL is that the system includes an energy supply subsystem. Based on the concept, energy supply subsystem using solar thermal energy as an energy source has been developed. This subsystem includes a Stirling engine generator. The prototype engines, called the NALSEM (NAL Stirling Engine Model) series, are semi-free-piston Stirling machines with a moving-magnet linear alternator. The NALSEM500 was designed to achieve thermodynamic efficiency of 30% or more with an indicated power of 500W. The design performance has been achievable to date. Based on this achievement, an improved Stirling engine generator, the NALSEM700,has been designed. This engine has an opposed-piston configuration to minimize mechanical vibration, and is expected to provide higher performance and stability than the NALSEM 500. This paper describes the significant design features and test results of the NALSEM700.
