Investigation of the operating characteristics of a free-piston closed-cycle Joule engine generator with helium as working fluid

As an emerging micro- or small-scale energy conversion technology, linear Joule engine generators (LJEGs) combine the advantages of external combustion engines and linear generators, feature the advantages of high thermal-to-electrical efficiency, multi-fuel potential, good operational flexibility,...

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Main Authors: Benlei Wang, Shunmin Zhu, Ugochukwu Ngwaka, Boru Jia, Kumar Vijayalakshmi Shivaprasad, Yaodong Wang, Andrew Smallbone, Anthony Paul Roskilly, Ercang Luo
Format: Article
Language:English
Published: Elsevier 2025-04-01
Series:Energy Conversion and Management: X
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Online Access:http://www.sciencedirect.com/science/article/pii/S2590174525000418
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author Benlei Wang
Shunmin Zhu
Ugochukwu Ngwaka
Boru Jia
Kumar Vijayalakshmi Shivaprasad
Yaodong Wang
Andrew Smallbone
Anthony Paul Roskilly
Ercang Luo
author_facet Benlei Wang
Shunmin Zhu
Ugochukwu Ngwaka
Boru Jia
Kumar Vijayalakshmi Shivaprasad
Yaodong Wang
Andrew Smallbone
Anthony Paul Roskilly
Ercang Luo
author_sort Benlei Wang
collection DOAJ
description As an emerging micro- or small-scale energy conversion technology, linear Joule engine generators (LJEGs) combine the advantages of external combustion engines and linear generators, feature the advantages of high thermal-to-electrical efficiency, multi-fuel potential, good operational flexibility, a simple and compact mechanical structure, and low frictional loss. Earlier research on LJEGs mainly focused on open-cycle systems, while closed-cycle LJEGs, which are the subject of this work, have some unique characteristics in comparison with open-cycle ones. Unfortunately, the operating features of closed-cycle LJEGs are still not well comprehended. To fill this gap, in this paper, the operating characteristics of a closed-cycle LJEG with helium as working fluid are investigated based on a validated numerical model. The dynamic characteristics and output performance of the system were investigated at different system pressures and compared with an open-cycle LJEG with air as working fluid. The outcomes reveal that the closed-cycle LJEG has a smaller piston stroke and higher output efficiency. Furthermore, the effect of key parameters such as valve timing, electrical resistance coefficient, and cylinder diameters on system performance is investigated. This study offers in-depth insights into the operation characteristics of the closed-cycle LJEG, which contributes to the design of similar systems.
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spelling doaj-art-bb77e70f65d04ec2909d036e729f83a52025-08-20T03:10:27ZengElsevierEnergy Conversion and Management: X2590-17452025-04-012610090910.1016/j.ecmx.2025.100909Investigation of the operating characteristics of a free-piston closed-cycle Joule engine generator with helium as working fluidBenlei Wang0Shunmin Zhu1Ugochukwu Ngwaka2Boru Jia3Kumar Vijayalakshmi Shivaprasad4Yaodong Wang5Andrew Smallbone6Anthony Paul Roskilly7Ercang Luo8Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, ChinaDepartment of Engineering, Durham University, Durham, DH1 3LE, UK; Corresponding authors.Department of Engineering, Durham University, Durham, DH1 3LE, UKSchool of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, ChinaDepartment of Engineering, Durham University, Durham, DH1 3LE, UKDepartment of Engineering, Durham University, Durham, DH1 3LE, UKDepartment of Engineering, Durham University, Durham, DH1 3LE, UKDepartment of Engineering, Durham University, Durham, DH1 3LE, UKKey Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China; Corresponding authors.As an emerging micro- or small-scale energy conversion technology, linear Joule engine generators (LJEGs) combine the advantages of external combustion engines and linear generators, feature the advantages of high thermal-to-electrical efficiency, multi-fuel potential, good operational flexibility, a simple and compact mechanical structure, and low frictional loss. Earlier research on LJEGs mainly focused on open-cycle systems, while closed-cycle LJEGs, which are the subject of this work, have some unique characteristics in comparison with open-cycle ones. Unfortunately, the operating features of closed-cycle LJEGs are still not well comprehended. To fill this gap, in this paper, the operating characteristics of a closed-cycle LJEG with helium as working fluid are investigated based on a validated numerical model. The dynamic characteristics and output performance of the system were investigated at different system pressures and compared with an open-cycle LJEG with air as working fluid. The outcomes reveal that the closed-cycle LJEG has a smaller piston stroke and higher output efficiency. Furthermore, the effect of key parameters such as valve timing, electrical resistance coefficient, and cylinder diameters on system performance is investigated. This study offers in-depth insights into the operation characteristics of the closed-cycle LJEG, which contributes to the design of similar systems.http://www.sciencedirect.com/science/article/pii/S2590174525000418Energy conversionFree-pistonLinear Joule engine generatorClosed Brayton cycleHelium
spellingShingle Benlei Wang
Shunmin Zhu
Ugochukwu Ngwaka
Boru Jia
Kumar Vijayalakshmi Shivaprasad
Yaodong Wang
Andrew Smallbone
Anthony Paul Roskilly
Ercang Luo
Investigation of the operating characteristics of a free-piston closed-cycle Joule engine generator with helium as working fluid
Energy Conversion and Management: X
Energy conversion
Free-piston
Linear Joule engine generator
Closed Brayton cycle
Helium
title Investigation of the operating characteristics of a free-piston closed-cycle Joule engine generator with helium as working fluid
title_full Investigation of the operating characteristics of a free-piston closed-cycle Joule engine generator with helium as working fluid
title_fullStr Investigation of the operating characteristics of a free-piston closed-cycle Joule engine generator with helium as working fluid
title_full_unstemmed Investigation of the operating characteristics of a free-piston closed-cycle Joule engine generator with helium as working fluid
title_short Investigation of the operating characteristics of a free-piston closed-cycle Joule engine generator with helium as working fluid
title_sort investigation of the operating characteristics of a free piston closed cycle joule engine generator with helium as working fluid
topic Energy conversion
Free-piston
Linear Joule engine generator
Closed Brayton cycle
Helium
url http://www.sciencedirect.com/science/article/pii/S2590174525000418
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AT ugochukwungwaka investigationoftheoperatingcharacteristicsofafreepistonclosedcyclejouleenginegeneratorwithheliumasworkingfluid
AT borujia investigationoftheoperatingcharacteristicsofafreepistonclosedcyclejouleenginegeneratorwithheliumasworkingfluid
AT kumarvijayalakshmishivaprasad investigationoftheoperatingcharacteristicsofafreepistonclosedcyclejouleenginegeneratorwithheliumasworkingfluid
AT yaodongwang investigationoftheoperatingcharacteristicsofafreepistonclosedcyclejouleenginegeneratorwithheliumasworkingfluid
AT andrewsmallbone investigationoftheoperatingcharacteristicsofafreepistonclosedcyclejouleenginegeneratorwithheliumasworkingfluid
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AT ercangluo investigationoftheoperatingcharacteristicsofafreepistonclosedcyclejouleenginegeneratorwithheliumasworkingfluid