Dynamic Analysis of Free-Piston Stirling Engine/Linear Alternator-Load System - Experimentally Validated

Kankam, M.D.; Rauch, J.; Santiago, Walter

doi:10.4271/929265

Cited by 15 publications

(7 citation statements)

References 4 publications

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“…The principles of the Stirling engine were applied to the new concept of linear or free piston engines as well. References [31][32][33][34][35][36][37][38] show mathematical models, simulations, and prototype designs of free piston Stirling engines. The linkage-flywheel mechanism is eliminated in free piston Stirling engines and an air spring is placed between the plunger and the piston.…”

Section: IVmentioning

confidence: 99%

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Linear engine development for series hybrid electric vehicles

Tóth-Nagy¹

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Linear Engine Development for Series Hybrid Electric Vehicles by Csaba Tóth-Nagy This dissertation argues that diminishing oil reserves, concern over global climate change, and desire to improve ambient air quality all demand the development of environment-friendly personal transportation. In certain applications, series hybrid electric vehicles offer an attractive solution to reducing fuel consumption and emissions. Furthermore, linear engines are emerging as a powerplant suited to series HEV applications. In this dissertation, a linear engine/alternator was considered as the auxiliary power unit of a range extender series hybrid electric vehicle. A prototype linear engine/alternator was developed, constructed and tested at West Virginia University. The engine was a 2-stroke, 2-cylinder, dual piston, direct injection, diesel engine. Experiment on the engine was performed to study its behavior. The study variables included mass of the translator, amount of fuel injected, injection timing, load, and stroke with operating frequency and mechanical efficiency as the basis of comparison. The linear engine was analyzed in detail and a simple simulation model was constructed to compare the trends of simulation with the experimental data and to expand on the area where the experimental data were lacking. The simulation was based on a simple and analytical model, rather than a detailed and intensely numerical one. The experimental and theoretical data showed similar trends. Increasing translator mass decreased the operating frequency and increased compression ratio. Larger mass and increased compression ratio improved the ability of the engine to sustain operation and the engine was able to idle on less fuel injected into the cylinder. Increasing the stroke length caused the operating frequency to drop. Increasing fueling or decreasing the load resulted in increased operating frequency. This projects the possibility of using the operating frequency as an input for feedback control of the engine. Injection timing was varied to investigate two different modes of engine operation experimentally. The two modes were direct injection compression ignition (DICI) and "pseudo" homogeneously charged compression ignition (PHCCI). Simulation was performed to include HCCI operation in the study. The study showed that the HCCI operation resulted in higher peak cylinder pressure than that of DICI operation. A combined genetic algorithm-artificial neural network predictor model was used along with the simulation model to find the combination of engine parameters that yielded the highest engine efficiency. The predictor-simulator model suggested the most efficient combination of engine parameters. I thank Dr. Nigel N. Clark for his guidance during my postgraduate studies. Not only he did provide invaluable input to my research, he also showed the way with his integrity, philosophy, and attitude. I also thank Dr.

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Section: IVmentioning

confidence: 99%

“…13.57 mm, mass: 1.9602 kg, fuel injected: 8.9 µl, injection timing: 24.4 mm, ignition timing: 10.3 mm. Figure 76 and Figure 77 show operation cycles for 25,35, and 45 kW of applied load. The engine simulation stalled at 46 kW.…”

Section: Pressure-position Diagrammentioning

confidence: 99%

Linear engine development for series hybrid electric vehicles

Tóth-Nagy¹

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“…A Venus mission presents extreme demands, since the ambient temperature is approximately 500 o C. Instrumentation within the lander will have to be maintained at a much 1 Graduate Student, EMAE, Mail Stop 7222, djb30@case.edu. 2 Professor, EECS, Mail Stop 7071, wsn@case.edu.…”

Section: Introductionmentioning

confidence: 99%

Stirling Duplex System Modeling for Control System Analysis

Buckmaster

Newman

2011

9th Annual International Energy Conversion Engineering Conference

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This paper presents Stirling-convertor modeling contributions developed under contract to NASA-Glenn Research Center in support of a lander mission to Venus. The extremely high ambient surface temperature imposes significant cooling requirements, and the dense atmosphere precludes the use of solar power. It is thus proposed that the lander be powered by heat from a radioisotope, which is converted by a Stirling engine into mechanical work. This then drives a coupled Stirling cooler and linear alternator for electrical power. The duplex system has only three moving parts (two displacers and a shared piston), and all are passively resonant; the only available means of control is through regulation of power absorbed by the alternator. This work presents extensions to prior techniques of converting nonlinear, steady-state descriptions of duplex-system dynamics into best-fit linear systems for evaluating transients, potential controllers, and system output. Additionally, efforts to describe cooler thermodynamics with linear systems are detailed, leading to a roadmap for a full, linear description of a Stirling duplex system. NomenclatureA = Linear-system state matrix A {cold,hot} = {Cold,Hot}-facing area of working piston A i,{cold,hot} = {Cold,Hot}-facing area of i th stage of multi-step displacer. i=1 is the warmest stage. B = Linear-system input matrix F {d,p},P = Force on {displacer,piston} due to pressure K m = Linear alternator force constant (Newtons per Amp) k P,{xd,xp,..} = Coefficient relating pressure to position/velocity {x,v} of displacer/piston {d,p} (e.g. xd -position of displacer) k spring = Linear spring stiffness L = Inductance P c = Compression-space pressure P e,i = Expansion-space pressure (of stage i, for multi-stage cooler) Q = Heat R = Resistance T = Temperature (Kelvin) v {p,d} = Velocity of {piston,displacer} v {p,d} = Periodic amplitude of {piston,displacer} velocity W = Work x {p,d} = Position of {piston,displacer}  {d,P} = Phase angle (radians) of {displacer,Pressure} (the working piston is the zero reference)  = Frequency (radians per second)

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“…Kankam, Rauch and Santiago [18] have formulated a mathematical model of a free piston Stirling engine and linear alternator combination by coupling the mechanical and thermodynamic properties of the engine with the electrical equations of the linear alternator and the electrical load. They then examine the changes in the dynamic system response to variations in system parameters.…”

Section: Literature Reviewmentioning

confidence: 99%

“…%Establish arrays for data storage t = 0:dt:tfinal*1.5; xa = zeros(size(t)); va = zeros(size(t)); aa = zeros(size(t)); ta = zeros(size(t)); %Setup initial conditions v = 0; x = -xs; count = 1; xa(count) = x; va(count) = v; aa(count) = eval(a); ta(count) = 0; count = count + 1; Y=fft(S,n); f=1/delta*(0:n/2-1)/n; C =(2/n)*abs(Y); phi = angle(Y); dC = zeros(size(C)); dphi = zeros(size(phi)); for i=2:length(f) dC(i) = -2*pi*f(i)*C(i); dphi(i) = phi(i)-pi/2; end; [14,13,15,16],'Tooth2'); % 4 Tooth2 [areas(5,:) aname(5,:)]=aline( [12,11,13,14],'Winding'); % 5 Winding [areas(6,:) aname(6,:)]=aline( [10,17,18,15,13,11],' Backiron'); % 6 Backiron % Generate those areas effected by changes in yoff % There are five distinct areas depending of the value of yoff. At % yoff = 0 the magnet is centered in the pole pitch at the point % of maximum flux linkage.…”

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confidence: 99%

Optimization of a brushless permanent magnet linear alternator for use with a linear internal combustion engine

Cawthorne¹

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Dynamic Analysis of Free-Piston Stirling Engine/Linear Alternator-Load System - Experimentally Validated

Cited by 15 publications

References 4 publications

Linear engine development for series hybrid electric vehicles

Linear engine development for series hybrid electric vehicles

Stirling Duplex System Modeling for Control System Analysis

Optimization of a brushless permanent magnet linear alternator for use with a linear internal combustion engine

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