THERMAL SCIENCE

International Scientific Journal

Mingyang Yuwen

,

Baoying Peng

,

Yonghong Xu

RESEARCH ON THE INFLUENCE OF INTAKE TEMPERATURE ON THE WORKING PERFORMANCE OF FREE PISTON EXPANDERS

ABSTRACT
The Free Piston Expander-Linear Generator is a high-performance Organic Rankine Cycle waste heat recovery technology. Based on a Free Piston Expander-Linear Generator experimental platform, this paper experimentally investigates the effects of intake temperature on the system's piston motion, electrical output and energy conversion efficiency. Higher intake temperature elevates piston displacement, velocity and motion symmetry, and positively correlates with the generator's output voltage and power, which hits a maximum of 31.06 W at 3.5 bar intake pressure and 20 Ω load resistance. A 3.5 bar pressure boosts the average power by 15 %-20 % compared with 3.0 bar, and a temperature-pressure synergy is observed: the output improvement induced by temperature is more prominent at low pressure, while its marginal effect weakens at high pressure. The energy conversion efficiency of the Free Piston Expander-Linear Generator rises with temperature but declines with increasing pressure and external load, with a maximum value of 41.03 % achieved in this study.
KEYWORDS
Free piston expander-linear generator, Output characteristics, Displacement characteristics, energy conversion efficiency, Intake Temperature
PAPER SUBMITTED: 2026-02-21
PAPER REVISED: 2026-05-12
PAPER ACCEPTED: 2026-05-19
PUBLISHED ONLINE: 2026-06-20
DOI REFERENCE: https://doi.org/10.2298/TSCI260221076Y
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Research on the influence of intake temperature on the working performance of free piston expanders

© 2026 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International licence