Investigation of the optimum operating condition of a dual piston type free piston engine generator during engine cold start-up process

Feng, Huihua; Zhang, Zhiyuan; Jia, Boru; Zuo, Zhengxing; Smallbone, Andrew; Roskilly, Anthony Paul

doi:10.1016/j.applthermaleng.2020.116124

Cited by 23 publications

(12 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Notably, these improvements persist even when the periodic energy input remains constant. An examination of the engine's optimal working conditions during cold starts, as reported in a previous study [9], revealed that the targeted CR holds paramount importance during this phase, with frequency exerting a comparatively negligible impact. The Sandia National Laboratory [10] designed a single-cylinder, opposed-piston, freepiston linear generator with potential applications in hybrid electric vehicle systems.…”

Section: Linear Engine Generatorsmentioning

confidence: 64%

Performance and Emission Optimisation of an Ammonia/Hydrogen Fuelled Linear Joule Engine Generator

Chen,

Ngwaka,

et al. 2024

Energies

View full text Add to dashboard Cite

This paper presents a Linear Joule Engine Generator (LJEG) powered by ammonia and hydrogen co-combustion to tackle decarbonisation in the electrification of transport propulsion systems. A dynamic model of the LJEG, which integrates mechanics, thermodynamics, and electromagnetics sub-models, as well as detailed combustion chemistry analysis for emissions, is presented. The dynamic model is integrated and validated, and the LJEG performance is optimised for improved performance and reduced emissions. At optimal conditions, the engine could generate 1.96 kWe at a thermal efficiency of 34.3% and an electrical efficiency of 91%. It is found that the electromagnetic force of the linear alternator and heat addition from the external combustor and engine valve timing have the most significant influences on performance, whereas the piston stroke has a lesser impact. The impacts of hydrogen ratio, oxygen concentration, inlet pressure, and equivalence ratio of ammonia-air on nitric oxide (NO) formation and reduction are revealed using a detailed chemical kinetic analysis. Results indicated that rich combustion and elevated pressure are beneficial for NO reduction. The rate of production analysis indicates that the equivalence ratio significantly changes the relative contribution among the critical NO formation and reduction reaction pathways.

show abstract

Section: Linear Engine Generatorsmentioning

confidence: 64%

Performance and Emission Optimisation of an Ammonia/Hydrogen Fuelled Linear Joule Engine Generator

Chen,

Ngwaka,

et al. 2024

Energies

View full text Add to dashboard Cite

show abstract

“…Piston dynamics can therefore be generalized using Newton's 2nd law of motion. This generalized approach is presented by numerous authors, including Goto et al [27] and Feng et al [28] in their respective physics-based modelling studies:…”

Section: Piston Dynamicsmentioning

confidence: 99%

“…The LEM is utilized as a generator during steady-state power generation, which can be described as a resistance or damping force. An idealized generating force Fgen description is typically used, which is shown as follows [32,28]: (4) where µ e is the generator coefficient, which is also described as the Back Electromotive Force (EMF) and is proportional to the piston velocity x˙; however, the above description may fail to capture the inherent nonlinear stator winding cross-coupling. Furthermore, it may neglect the influence of rectifying the generated Alternating Current (AC) to Direct Current (DC) on the motor force and any subsequently induced harmonics.…”

Section: Linear Electric Machinementioning

confidence: 99%

A Comprehensive Review of the Free Piston Engine Generator and Its Control

Brosnan

Tian²,

Montanaro³

et al. 2023

IJAMM

View full text Add to dashboard Cite

Review A Comprehensive Review of the Free Piston Engine Generator and Its Control Patrick Brosnan 1, Guohong Tian 1, * , Umberto Montanaro 1, and Sam Cockerill 2 1 School of Mechanical Engineering Sciences, University of Surrey, Surrey GU2 7XH, UK 2 Libertine FPE Ltd., Sheffield S9 1DA, UK * Correspondence: g.tian@surrey.ac.uk; Tel.: +44-1483-300-800 Received: 2 February 2023 Accepted: 10 March 2023 Published: 23 March 2023 Abstract: The Free Piston Engine (FPE) is a unique machine with a higher thermal efficiency than its counterpart, the Conventional Reciprocating Piston Engine (CPE). The unique piston motion of the FPE is not constrained kinematically like the CPE with its connecting crankshaft and rotational inertial masses. Moreover, when directly coupled to the Linear Electric Machine (LEM) to harness electric energy production, the Free Piston Engine Generator’s (FPEG) characteristic motion, now being dynamically constrained, permits an extensive range of piston trajectory profiles to be exploited during operation. In addition, exploring varied piston trajectories during the development stages may be vital in reducing in-cylinder combustion emissions through strategies such as Low-Temperature Combustion (LTC) and Homogeneous Charge Compression Ignition (HCCI). This review paper will focus on the key motivations and drivers for continued FPEG development. It will also highlight and review its distinct advantages and challenges in being a viable solution as a future zero-carbon engine technology. Finally, FPE fundamentals, alongside its rich history, will be introduced, clearly presenting how academia and industry have described and controlled its intrinsic non-linear dynamics.

show abstract

“…The FPE was developed from the motor compressor apparatus proposed by the authors of [20], which eliminated the crank linkage mechanism of the reciprocating piston expander, allowing the piston to move freely within the cylinder. These features give it the advantages of compact structure, good sealability, low friction, high efficiency, and variable expansion ratio [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Performance Prediction and Optimization of Single-Piston Free Piston Expander-Linear Generator Based on Machine Learning and Genetic Algorithm

Li,

Zuo,

Jia

et al. 2024

International Journal of Energy Research

Self Cite

View full text Add to dashboard Cite

This paper proposed a single-piston free piston expander-linear generator (SFPE-LG) prototype applied to organic Rankine cycle systems. Two valve timing control strategies, namely, time control strategy (TCS) and position control strategy (PCS), were developed. Based on the experimental data, a back propagation neural network (BPNN) prediction model was established. The effects of structural parameters such as neural network layers, transfer function, training function, hidden layer nodes, and learning rate on the prediction accuracy of this BPNN model were discussed. The training and prediction accuracy of the BPNN model was verified using 5-fold cross-validation and Wilcoxon signed-rank test. Moreover, the BPNN model was integrated with a genetic algorithm to predict and optimize the maximum output power of the SFPE-LG. The results showed that the BPNN model used to predict the motion characteristics and output performance of the SFPE-LG exhibits strong learning ability and high prediction accuracy. Notably, the prediction accuracy of the BPNN model is significantly higher under the PCS compared to TCS. The effect of hidden layer nodes on mean square error (MSE) and correlation coefficient (R) is greater than that of the learning rate. When the number of hidden layer nodes exceeds 30, the BPNN model consistently achieves low MSE and high R. The optimization results showed that the SFPE-LG can obtain a maximum output power of 141.69 W under the TCS, when the working parameters are inlet pressure of 0.7 MPa, intake duration of 35 ms, load resistance of 67 Ω, and expansion duration of 104 ms, respectively.

show abstract

Investigation of the optimum operating condition of a dual piston type free piston engine generator during engine cold start-up process

Cited by 23 publications

References 21 publications

Performance and Emission Optimisation of an Ammonia/Hydrogen Fuelled Linear Joule Engine Generator

Performance and Emission Optimisation of an Ammonia/Hydrogen Fuelled Linear Joule Engine Generator

A Comprehensive Review of the Free Piston Engine Generator and Its Control

Performance Prediction and Optimization of Single-Piston Free Piston Expander-Linear Generator Based on Machine Learning and Genetic Algorithm

Contact Info

Product

Resources

About