A novel active free piston Stirling engine: Modeling, development, and experiment

Tavakolpour-Saleh, A.R.; Zare, Shahryar; Bahreman, H.

doi:10.1016/j.apenergy.2017.05.059

Cited by 68 publications

(28 citation statements)

References 23 publications

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“…Next, according to the obtained periodic motion, the piston displacement must be studied. Indeed, due to the FPSE behavior, it is vital to achieve a stable periodic motion, and the only strategy is to generate a periodic motion with a set of parameters in the displacer piston [4,7,16]. The simulated instantaneous velocity of the power and displacer pistons according to the fifth-order model is represented in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…As a result, the operation of expansion engines based on the Stirling cycle can be remarked as one of the beneficial aspects of such engines. Figure 2 demonstrates the working principles of the FPSE as follows [4]:…”

Section: Free-piston Stirling Engines (Fpses)mentioning

confidence: 99%

“…Up to now, many researchers have conducted extensive works to design and analyze these types of engines. High efficiency, self-starting, and long operating life can be noted as one of the major advantages [4,5]; however, despite these advantages, designing and setting up these types of engines has been a major challenge for scientists. The dynamic structure of the FPSEs is such that the motion of the pistons of the system must reach the unstable or marginally stable (in linear analysis) and in nonlinear analysis achieve a stable limit cycle [6,7], but unfortunately this condition involves a lot of complexity in the design procedures of Stirling engines.…”

Section: Introductionmentioning

confidence: 99%

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Higher order modeling of a free-piston Stirling engine: analysis and experiment

Zare

Shourangiz-Haghighi

2018

Int J Energy Environ Eng

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This paper focuses on higher order modeling and design of the free-piston Stirling engine (FPSE) based on Ant Colony Optimization (ACO). First, the governing thermodynamics and dynamical equations of the engine have been derived. Then, the design parameters of the engine are selected taking into account the finite heat transfer coefficient (resulting in a fifth-order model) and pressure drop (resulting in a sixth-order model) in the dynamical system and the corresponding differential equations are derived in detail. In the following, the mentioned methods and their performance in modeling the FPSE dynamics are investigated. The simulated results show that the effect of the pressure drop on the places of the closed-loop poles of the system is not significant, while the heat transfer coefficient has a considerable effect on the engine dynamics. Accordingly, a fifth-order model along with ACO algorithm is proposed to justify the FPSE behavior. To validate the presented modeling scheme, the prototype engine SUTECH-SR-1 was experimented. It is found that the values of parameters obtained from the proposed design method are close to those of the experiment. Besides, the presented higher order model predicts the engine behavior with an acceptable accuracy through which the validity of the design technique is affirmed. Initial pressure of working gas (Pa) P w Power generation (J/s) P Nonlinear pressure (Pa) R Ideal gas constant J kgVolume of expansion space m

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Section: Resultsmentioning

confidence: 99%

Section: Free-piston Stirling Engines (Fpses)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Higher order modeling of a free-piston Stirling engine: analysis and experiment

Zare

Shourangiz-Haghighi

2018

Int J Energy Environ Eng

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“…unstable characteristic caused by the variation of output load is inevitable. Effective control strategy is studied to improve the robustness of the generating system to meet the demands of the generating process and improve the stability of the output current of free-piston Stirling generating system [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Research on Control Strategy of Free-Piston Stirling Power Generating System

et al. 2017

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Abstract:As a clean and fuel adaptive alternative power plant, the Stirling power generating system has drawn attention of experts and scholars in the energy field. In practical application, the instability of free-piston Stirling power generating system caused by abrupt load change is an inevitable problem. Thus, methods to improve the output frequency response and stability of the free-piston Stirling power generating system are necessary. The model of free-piston Stirling power generating system is built by isothermal analysis firstly, and the initial control strategy based on given voltage system is put forward. To further improve the performance of power system, a current feedback decoupling control strategy is proposed, and the mathematical model is established. The influence of full decoupled quadrature-direct (d-q) axis currents is analyzed with respect to the output voltage adjusting time and fluctuation amplitude under the variations of piston displacement and output load. The simulation results show that the system performance is significantly improved, but the dynamic regulation lags caused by the decoupled current control still exist. To solve this problem and improve the performance of decoupled-state feedback current control that relies on parameter accuracy, internal model control based on sliding mode (IMC-SM) current decoupling control strategy is proposed, the system model is established, and then the performance of voltage ripple in generating mode is improved. Finally, the test bench is built, and the steady state and transient voltage control performances are tested. The feasibility and priority of the control strategy is verified by experiment and simulation results.

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“…Consequently, many researchers have proposed different mathematical models to predict the performance of such engines, each of which possesses particular advantages and drawbacks. Beale [10][11][12] carried out the first dynamic analysis of the FPSE. Walker and Senft [5] presented another preliminary analysis on FPSEs considering the assumptions of Schmidt's theory.…”

Section: Introductionmentioning

confidence: 99%

From Beale Number to Pole Placement Design of a Free Piston Stirling Engine

Zare

Omidvar

2017

Archive of Mechanical Engineering

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In this paper, pole placement-based design and analysis of a free piston Stirling engine (FPSE) is presented and compared to the well-defined Beale number design technique. First, dynamic and thermodynamic equations governing the engine system are extracted. Then, linear dynamics of the free piston Stirling engine are studied using dynamic systems theory tools such as root locus. Accordingly, the effects of variations of design parameters such as mass of pistons, stiffness of springs, and frictional damping on the locations of dominant closed-loop poles are investigated. The design procedure is thus conducted to place the dominant poles of the dynamic system at desired locations on the s-plane so that the unstable dynamics, which is the required criterion for energy generation, is achieved. Next, the closed-loop poles are selected based on a desired frequency so that a periodical system is found. Consequently, the design parameters, including mass and spring stiffness for both power and displacer pistons, are obtained. Finally, the engine power is calculated through the proposed control-based analysis and the result is compared to those of the experimental work and the Beale number approach. The outcomes of this work clearly reveal the effectiveness of the control-based design technique of FPSEs compared to the well-known approaches such as Beale number.

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A novel active free piston Stirling engine: Modeling, development, and experiment

Cited by 68 publications

References 23 publications

Higher order modeling of a free-piston Stirling engine: analysis and experiment

Higher order modeling of a free-piston Stirling engine: analysis and experiment

Research on Control Strategy of Free-Piston Stirling Power Generating System

From Beale Number to Pole Placement Design of a Free Piston Stirling Engine

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