Applying perturbation technique to analysis of a free piston Stirling engine possessing nonlinear springs

Int J Energy Environ Eng

Shourangiz-Haghighi

2018

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

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Int J Energy Environ Eng

Shourangiz-Haghighi

2018

“…The output power of the prototype engine was measured as 2.7 W at frequency of 67.9 rad/s. More details on the experimental work and the measurement technique can be found in [21]. …”

Section: Measured Output Power Of the Experimental Enginementioning

confidence: 99%

“…As a prototype FPSE, the SUTech-SR-1 developed at Shiraz University of Technology [21] was considered in this work. The specifications of the mentioned FPSE were given in Table 1.…”

Section: Analysis Of a Fpse Using Roots Locimentioning

confidence: 99%

“…Boucher et al [20] carried out an analysis on a free piston Stirling engine possessing a power piston and two displacers and then, obtained optimum values of design parameters for 1 kW output power. Tavakolpour-Saleh et al [21] applied a perturbation technique to the analysis of a FPSE possessing nonlinear springs. The method of multiple-scale was used in this investigation to achieve the final solutions of the governing nonlinear differential equations.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Archive of Mechanical Engineering

Omidvar

2017

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.

Free piston Stirling engines: A review

Tavakolpour-Saleh

2019

Int J Energy Res

Self Cite

This paper presents a detailed review on free piston Stirling engines (FPSEs) technology. Generally, the Stirling engines can be categorized into two broad classes comprising kinematic and dynamic converters among which FPSEs are known as the dynamic type. Other well-known dynamic Stirling converters are Fluidyne and thermosacoustic engines among which the thermosacoustic ones are the most advanced Stirling converters recently presented. In this research, the dynamic Stirling engines are first introduced and reviewed. Then, the review work is directed toward the FPSEs, one of the most reliable dynamic Stirling converters utilized in different applications such as combined heat and power systems (CHPs). Subsequently, the working principles of different types of FPSEs and their performance are summarized. Next, several manufactured FPSEs, as well as their corresponding features and applications, are discussed. Finally, the article is conducted to analysis and modeling approaches of FPSEs.Accordingly, linear and nonlinear analytical techniques of FPSEs are introduced, and some comparative data are provided to verify the modeling schemes. Then, various design parameters affecting the engine performance are introduced and studied. The outcomes of this review work demonstrate the potential of FPSEs for different applications and reveal that the perturbation-based model is likely the most comprehensive nonlinear method for modeling and design of the FPSEs.