Abstract This paper presents a single-piston free piston expander-linear generator for small-scale organic Rankine cycle. In order to achieve stable operation, two types of valve timing control methods are developed: time control method (TCM) and position control method (PCM). The orthogonal experimental design is adopted to evaluate the influence degree and significance level of different factors on the prototype performance. Results show that the symmetry motion characteristics are worse when the TCM is used than those of the PCM. Furthermore, such characteristics could be improved by appropriately increasing expansion duration and intake duration tBT. For the PCM, operating frequency gradually increases as external resistance, intake pressure, and intake duration but significantly decreases as theoretical stroke. For the TCM, operating frequency is only related with intake and expansion durations. Intake pressure has the greatest influence on the peak power output, peak velocity, and actual stroke length, followed by intake duration. Theoretical stroke is the dominant factor affecting operating frequency, followed by intake pressure, and then by intake duration and external resistance. Thermal-work, work-electric, and thermal-electric conversion efficiencies can achieve a maximum of 5.4%, 28.8%, 1.4%, respectively.

中文翻译：

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单活塞自由活塞膨胀机-线性发电机不同气门正时控制方法的正交试验对比分析

摘要 本文提出了一种用于小型有机朗肯循环的单活塞无活塞膨胀机-线性发电机。为了实现稳定运行，开发了两种气门正时控制方法：时间控制法（TCM）和位置控制法（PCM）。采用正交试验设计，评价不同因素对样机性能的影响程度和显着性水平。结果表明，当使用TCM 时，对称运动特性比使用PCM 时更差。此外，可以通过适当增加膨胀持续时间和进气持续时间tBT来改善这些特性。对于PCM，工作频率随着外部阻力、进气压力和进气持续时间逐渐增加，但随着理论冲程而显着降低。对于中医来说，操作频率仅与吸入和膨胀持续时间有关。进气压力对峰值功率输出、峰值速度和实际冲程长度的影响最大，其次是进气持续时间。理论冲程是影响工作频率的主要因素，其次是进气压力，其次是进气持续时间和外部阻力。热功、功电和热电转换效率最高可分别达到5.4%、28.8%、1.4%。