Design and Performance of a Diaphragm Free-Piston Stirling Engine for Power Production From Low-Temperature Heat Sources

2018 ◽  
Author(s):  
Anas Nawafleh ◽  
Khaled R. Asfar
Keyword(s):  
Low Temperature ◽  
Waste Heat ◽  
Engine Performance ◽  
Surface Friction ◽  
Stirling Engine ◽  
Operating Conditions ◽  
Physical Parameters ◽  
Free Piston ◽  
And Performance ◽  
Free Piston Stirling Engine

This paper addresses modeling, design, and experimental assessment of a Gamma type low-temperature differential free-piston Stirling engine. The most advanced third-order design analysis method is used to model, simulate and optimize the engine. Moreover, the paper provides an experimental parametric investigation of engine physical parameters and operating conditions on the engine performance. The experimental test results are presented for a model validation, which shows about a 5% to 10% difference in the simulation results. The aim of this study is to design a Stirling engine capable of harvesting low-temperature waste heat effectively and economically and convert it to power. The engine prototype is designed to increase the engine performance by eliminating the main losses occurred in conventional Kinematic engines. Thus, elastic diaphragm pistons are used in this prototype to eliminate the surface friction of the moving parts, the use of lubricant, and to provide appropriate seals. In addition, flat plate heat exchangers, linear flexure bearing, a stainless-steel regenerator and a polyurethane displacer are outlined as the main components of the engine. Experiments successfully confirm the design models for output power and efficiency. Furthermore, it is revealed that the displacer-to-piston natural frequency ratio is an important design point for free-piston Stirling engines and should be addressed in the design for optimum power output.

Design of a Free Piston Stirling Engine Power Generator

2019 ◽  
Author(s):  
Ruijie Li ◽  
Yuan Gao ◽  
Koji Yanaga ◽  
Songgang Qiu
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Waste Heat ◽  
Combustion Engine ◽  
Engine Performance ◽  
Flow Distribution ◽  
Stirling Engine ◽  
Free Piston ◽  
Free Piston Stirling Engine

Abstract Free Piston Stirling Engine is an external combustion engine, which can use diversified energy resources, such as solar energy, nuclear energy, geothermal energy, biomass, industrial waste heat etc. and is suitable for the remote area power generation due to the advantage of robustness, durability, reliability, and high efficiency. In this work, a Free Piston Stirling Engine has been designed based on the numerical simulation results and previous experimental experience. Direct Metal Laser Sintering method has been adopted for the manufacturing of the key components including the displacer cap, displacer body, piston housing, cold heat exchanger, and regenerator. One dimension analysis using Sage software has been conducted. The designed engine has a power output of 65W with the hot and cold end temperature is 650°C and 80°C respectively, and charge pressure is 1.35 MPa. Finite Element Method has been used to analyze the structural stress of the engine, which is operated at the high temperature and high pressure, to determine if it is able to tolerate the operating condition designed by the Sage according to the Section VIII Division 2 of the ASME Boiler and Pressure Vessel (BPV) Code. In addition, Computational Fluid Dynamics (CFD) method has been used to investigate the flow distribution in heat exchangers (heat acceptor, regenerator, and heat rejecter), as the heat exchanger performance affect the engine performance greatly. Considering the large mesh number, a quarter of the heat exchangers have been investigated, in order to reduce the mesh numbers and accelerate the calculation speed.

scholarly journals Optimisation of a Quasi-Steady Model of a Free-Piston Stirling Engine

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 72 ◽  
Author(s):  
Ayodeji Sowale ◽  
Edward Anthony ◽  
Athanasios Kolios
Keyword(s):  
Power Systems ◽  
Thermal Efficiency ◽  
Waste Heat ◽  
Stirling Engine ◽  
Design Parameters ◽  
Free Piston ◽  
Output Performance ◽  
Free Piston Stirling Engine ◽  
External Combustion ◽  
Work Done

Energy from waste heat recovery is receiving considerable attention due to the demand for power systems that are less polluting. This has led to the investigation of external combustion engines such as the free-piston Stirling engine (FPSE) due to its ability to generate power from any source of heat and, especially, waste heat. However, there are still some limitations in the modelling, design and practical utilisation of this type of engine. Modelling of the FPSE has proved to be a difficult task due to the lack of mechanical linkages in its configuration, which poses problems for achieving stability. Also, a number of studies have been reported that attempt to optimise the output performance considering the characteristics of the engine configuration. In this study the optimisation of the second-order quasi-steady model of the gamma-type FPSE is carried out using the genetic algorithm (GA) to maximise the performance in terms of power output, and considering the design parameters of components such as piston and displacer damper, geometry of heat exchangers, and regenerator porosity. This present study shows that the GA optimisation of the RE-1000 FPSE design parameters improved its performance from work done and output power of 33.2 J and 996 W, respectively, with thermal efficiency of 23%, to 44.2 J and 1326 W with thermal efficiency of 27%.

scholarly journals Investigation on Stability and Performance of a Free-piston Stirling Engine

2014 ◽  
Vol 52 ◽  
pp. 598-609 ◽  
Author(s):  
Sutapat Kwankaomeng ◽  
Banterng Silpsakoolsook ◽  
Pongnarin Savangvong
Keyword(s):  
Stirling Engine ◽  
Free Piston ◽  
And Performance ◽  
Free Piston Stirling Engine

Development and Performance Measurements of a Beta-Type Free-Piston Stirling Engine Along With Dynamic Model Predictions

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Kyuho Sim ◽  
Dong-Jun Kim
Keyword(s):  
Dynamic Model ◽  
Stirling Engine ◽  
Electric Heater ◽  
Performance Measurements ◽  
Free Piston ◽  
Dynamic Behaviors ◽  
Output Performance ◽  
Model Predictions ◽  
And Performance ◽  
Free Piston Stirling Engine

This paper presents the development and performance measurements of a beta-type free-piston Stirling engine (FPSE) along with dynamic model predictions. The FPSE is modeled as a two degrees-of-freedom (2DOF) vibration system with the equations of motion for displacer and piston masses, which are connected to the spring and damping elements and coupled by working pressure. A test FPSE is designed from root locus analyses and developed with flexure springs and a dashpot load. The stiffness of the test springs and the damping characteristics of the dashpot are identified through experiments. An experimental test rig is developed with an electric heater and a water cooler, operating under the atmospheric air. The piston dynamic behaviors, including the operating frequency, piston stroke, and phase angle, and engine output performance are measured at various heater temperatures and external loads. The experimental results are compared to dynamic model predictions. The test FPSE is also compared to a conventional kinematic engine in terms of engine output performance and dynamic adaptation to environments. Incidentally, nonlinear dynamic behaviors are observed during the experiments and discussed in detail.

Investigation of a MEMS-Based Boiler and Free Piston Expander for Energy Harvesting

2012 ◽  
Author(s):  
C. Champagne ◽  
L. Weiss
Keyword(s):  
Dynamic Testing ◽  
Waste Heat ◽  
Maximum Velocity ◽  
Operating Conditions ◽  
Small Scale ◽  
Operational Parameters ◽  
Piston Motion ◽  
Free Piston ◽  
Static Test ◽  
And Performance

Initial investigations of a small-scale Free Piston Expander (FPE) are presented. In final form, the FPE will be a MEMS-based device capable of operation from low temperature waste heat sources. In this present study, a millimeter scale device is constructed and tested to yield insight into critical operational parameters. Different constructions and operating conditions are considered as are the effects on basic piston motion and performance. These include piston length and mass. In addition, different sealing and lubricating fluids are considered. Construction of this testbed device is via concentric copper tubing, allowing an effective baseline study of these determining parameters. Results show that, while thick lubricants seal well in a static test, piston motion is decreased in a dynamic test indicating leakages. By contrast, reduced viscosity lubricants dont seal as well in a static test, but yield increased piston motion in dynamic testing. This indicates effective sealing. The trends established by the study of varying viscosity lubricants hold true for pistons of increasing mass and length as well. A mixture of isopropanol and water performed well in these tests, and represented a low viscosity sealing fluid. Compared to conditions where no lubricant was used, maximum velocity was increased up to 50%. These results indicate that a thin, wetting fluid will be the best lubricant for the FPE, due to increased sealing and performance when in dynamic operation.

scholarly journals Numerical Analysis of the Adiabatic and Quasi Steady Model of Free Piston Stirling Engine

2018 ◽  
Vol 198 ◽  
pp. 04005
Author(s):  
Ayodeji Sowale ◽  
Athanasios J. Kolios
Keyword(s):  
Output Power ◽  
Stirling Engine ◽  
Operating Conditions ◽  
Design Parameters ◽  
Stable Operation ◽  
Free Piston ◽  
Temperature Efficiency ◽  
Mathematical Equations ◽  
Free Piston Stirling Engine ◽  
Good Agreement

This study presents the numerical simulation of the adiabatic and Quasi steady models of the free piston Stirling engine, the mathematical equations are presented, and design parameters are determined and used as input for the simulation. The simulations are computed under adiabatic and Quasi operating conditions, and their output results are compared. The similarities and differences in the model predictions in terms of the pressure to volume diagram, the amplitudes of the pistons and displacer, temperature, efficiency, power output and stable operation are observed and investigated. The models are validated against the experimental output and the results show a good agreement with the experiment. The adiabatic model predicted an output power of 862 W, while Quasi steady model predicted more accurate output power of 997W at frequency of 30 Hz in relation to the 1000 W of the experimental output. The effects of the variation of engine’s parameters on the output power are also observed and presented.

A design method for selecting the physical parameters of a free piston Stirling engine

2016 ◽  
Vol 231 (13) ◽  
pp. 2441-2450 ◽  
Author(s):  
Seon-Jun Jang ◽  
Michael J Brennan ◽  
Fadi Dohnal ◽  
Yoon-Pyo Lee
Keyword(s):  
Design Method ◽  
Damping Ratio ◽  
Feedback Mechanism ◽  
Stirling Engine ◽  
Physical Parameters ◽  
Operation Condition ◽  
Free Piston ◽  
Design Values ◽  
Nyquist Stability ◽  
Free Piston Stirling Engine

A new design method for selecting the physical parameters of a free piston Stirling engine (FPSE) is presented. The dynamics of FPSE are described in the form of a transfer function including the inherent feedback mechanism. The simplified Nyquist stability criterion is used to derive the operation condition, where the indices of the magnitude amplification factor (MAF) and the operation limit factor (OLF) are introduced in terms of the physical parameters. Further, a measure for the efficiency of the engine is defined as the damping ratio of the power piston system (DRP). Parametric studies of these quantities are carried out as well as benchmarking against the design values of the standard RE-1000 engine. A design method is presented that defines the physical parameters of an FPSE which is working at a given operation frequency.

scholarly journals A method for evaluating the heat rejection efficiency in a Lunar power plant consisting of a free-piston Stirling engine (FPSE)

2021 ◽  
Vol 313 ◽  
pp. 07001
Author(s):  
Sergey Smirnov ◽  
Mikhail Sinkevich ◽  
Yuri Antipov ◽  
Hassan Khalife
Keyword(s):  
Power Plant ◽  
Waste Heat ◽  
Exchange Process ◽  
Stirling Engine ◽  
Free Piston ◽  
Maximum Heat ◽  
Heat Rejection ◽  
Surface Areas ◽  
Heat Exchange Process ◽  
Free Piston Stirling Engine

A method for evaluating the heat rejection efficiency in a Lunar power plant consisting of a free-piston Stirling engine FPSE is proposed. The waste heat from the FPSE is absorbed by the refrigerant circulating in a closed pumped loop and then rejected through a radiator into space. The magnitude of the heat flux rejected through the radiator is determined by the temperature difference between the radiator fins and surrounding environment, as well as the surface areas of the radiator and the emissivity coefficient. The method developed is used to qualitatively evaluate the refrigerant efficiency based on calculating the average temperature of the radiator fin which is established during the heat exchange process in the radiator. The method allowed us to determine the most efficient refrigerant in terms of maximum heat rejection at a given operating temperature range without the need of detailed calculations like in the previous works of the authors. Computational studies in a two-dimensional formulation of the radiator, using helium or liquid ammonia as a refrigerant, to determine the quantitative characteristics of the heat rejection process and overall dimensions of the radiator were performed, and a comparative analysis of the results is presented.

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