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.

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

2016 ◽  
Author(s):  
Kyuho Sim ◽  
Dong-Jun Kim
Keyword(s):  
Engine Performance ◽  
Pressure Amplitude ◽  
Performance Measurements ◽  
Free Piston ◽  
Model Predictions ◽  
Load Tests ◽  
Working Frequency ◽  
And Performance ◽  
Piston Stroke ◽  
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. A test FPSE, composed of two pistons and spring elements, is designed by drawing root locus trajectories from linear eigenvalue analysis. Piston springs are developed by using finite element stress analyses and validated through static load-deflection tests. An experimental test rig for a manufactured FPSE includes ceramic heater, water cooler, and external dashpot. Tests are conducted with the atmospheric air at increasing heater temperatures under no load and external load conditions. Firstly, no load tests at increasing heater temperatures show significant increases in both piston stroke and pressure amplitude, but negligible changes in working frequency. Pressure-volume (P-V) power and thermal efficiency also increase significantly. Interestingly, dynamic discontinuities occur during continuous variations of heater temperature, demonstrating sudden increases in engine performance as well as operation uncertainty. Besides, cooling flow rate is found to have minimal influence on engine performance. Secondly, external load tests for increasing damping loads demonstrate considerable decreases in piston stroke, pressure amplitude and P-V power, but negligible changes in working frequency; while shaft power increases then decreases having an optimal operating load. Finally, the test FPSE is turned out to adapt itself to variations in heater temperatures and external loads by changing piston strokes and their phase angle.

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

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.

A Lumped-Parameter Dynamic Model of a Thermal Regenerator for Free-Piston Stirling Engines

2009 ◽  
Author(s):  
Mark Hofacker ◽  
James Kong ◽  
Eric J. Barth
Keyword(s):  
Dynamic Model ◽  
Control Volume ◽  
Matrix Material ◽  
Stirling Engine ◽  
Functional Requirements ◽  
Free Piston ◽  
Lumped Parameter ◽  
Dynamics And Control ◽  
Free Piston Stirling Engine ◽  
And Control

This paper uses lumped parameter dynamic equations to model the mass flow, piston dynamics, and control volume behavior inside a free-piston Stirling engine. A new model for a Stirling engine thermal regenerator that incorporates a dynamically changing temperature gradient is presented. The use of graphite as a regenerator matrix material is justified despite its limited background by comparing the functional requirements of regenerators to heat exchangers where graphite use is commonplace. Experimental results are used to characterize a graphite regenerator and validate the dynamic model.

Nanogrid for Home Application for Micro CHP based on Free Piston Stirling Engine

2020 ◽  
Author(s):  
Daniele Menniti ◽  
Anna Pinnarelli ◽  
Nicola Sorrentino ◽  
Giuseppe Barone ◽  
Giovanni Brusco ◽  
...  
Keyword(s):  
Stirling Engine ◽  
Free Piston ◽  
Free Piston Stirling Engine
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