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.

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.

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.

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

scholarly journals CFD methodology for simulating pumping loss from displacer and piston seals of free piston Stirling engine

2020 ◽  
pp. 295-295
Author(s):  
Umair Munir ◽  
Muhammad Kamran ◽  
Asad Shah ◽  
Muhammad Farhan ◽  
Zahid Anwar
Keyword(s):  
Power Efficiency ◽  
Gas Flow ◽  
Power Converter ◽  
Stirling Engine ◽  
Maximum Deviation ◽  
Pressure Amplitude ◽  
Gas Temperature ◽  
Free Piston ◽  
Piston Seal ◽  
Free Piston Stirling Engine

A new axisymmetric CFD model capable of describing pumping loss is proposed for free piston Stirling engine (FPSE). Inclusion of clearance seals, bounce space, heater, cooler and regenerator in a single model is the unique strength of this work. For transient simulation of engine, dynamic mesh was utilized for catering needs of moving boundaries. The model was validated with 12.5 kW component test power converter (CTPC) and successfully predicted indicated power, efficiency, pressure amplitude, pressure drop, and gas temperature in expansion and compression space at different piston amplitudes with 6% maximum deviation. The results showed that the heat exchange at heater and cooler was minimized at each flow reversal and was strongly influenced by oscillating gas flow rate. The results also present optimum displacer and piston seal clearance at different charge pressure and operating frequencies. The displacer seal clearance could be increased up to 125?m without compromising power: however, engine output was severely affected with increasing piston seal gap.

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.

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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