Design Exploration of a Miniaturized Stirling Engine

Abstract

Increased interest in long-term space exploration has increased demand for small yet powerful energy sources, especially for remote and harsh environments where traditional power sources may be impractical. In such scenarios, space probes and high-reliability systems necessitate innovative solutions to meet their growing power and thermal management requirements while maintaining small form factors. Presently, micro power systems fall short of achieving the desired efficiencies for these applications, typically hovering around 2% [1]. Stirling engines, with their proven capability to attain high thermodynamic efficiency (30-40%), offer a promising solution if this efficiency can be maintained in a miniaturized form [2]. This study delves into the design space of a miniaturized Stirling engine with a target input of 2Wth, which could be tailored for small-scale (mesoscale ~cm3 ) high-efficiency power generation or micro-cooling. Previous research has laid the groundwork for understanding the thermodynamics of miniaturized Stirling engines, exposing substantial challenges, including overwhelming parasitic losses at this scale. The current study endeavors to mitigate these losses and explore the path to optimal efficiencies through Simulink modeling. Simulations have demonstrated design spaces capable of producing mechanical efficiencies as high as 14% with a 2Wth input, marking significant progress in addressing the limitations of current micro power systems. The research's innovative approach has significant implications for enabling the power generation required for small space probes, particularly for long durations and need self-sustaining power over extended periods [3], [4]. As the study advances, it holds the promise of developing a physical prototype using the findings from the design space study, which helps push the field forward for future power generation and micro-cooling in small-scale space technology. This thesis aims to map the design space of a miniaturized Stirling engine focusing on mitigating parasitic losses to achieve markedly greater efficiency compared to existing technologies.