A Microfabricated Involute-Foil Regenerator for Stirling Engines

Tew, Roy C.; Ibrahim, Mounir B.; Dănilă, D. M.; Simon, Terrence W.; Mantell, Susan C.; Sun, Liyong; Gedeon, David; Kelly, Kevin W.; McLean, Jeffrey; Wood, Graham R.; Qiu, Songgang

doi:10.2514/6.2007-4739

Cited by 9 publications

(6 citation statements)

References 6 publications

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“…Gedeon 14 recognized N k as axial conductivity enhancement due to thermal dispersion having a Peclet dependence of the form (c 1 + c 2 Re m Pr n ) where c 1 and c 2 are constants and m and n are positive constants. This functional form for the dispersion agrees with other empirical predictions 32,34 . The parameters Į Ȟ and H are the surface area per unit volume and the convective heat transfer coefficient respectively.…”

Section: Volume-averaged Conservation Of Energy Equationsupporting

confidence: 78%

“…(34)) is the contribution due to viscous dissipation. Equation (32) seems to imply that the internal thermodynamic losses can be minimized by minimizing the magnitude of these local temperature and velocity gradients and the sum of their squares, throughout the domain of interest. Although a reduction in the fluid viscosity would lead to a reduction of the velocity gradients at the wall and the boundary layer viscous losses and an increase the fluid thermal conductivity would reduce the temperature gradients at the wall, and the conductive heat transfer loss; these measures are difficult or impractical to implement.…”

Section: Non-porous Regions Of the 3-space Domainmentioning

confidence: 99%

“…These efforts have been categorized into areas of materials and geometry, numerical modeling, and experimental measurement 17,23,29,32,35 . A NASA regenerator research grant effort led by Cleveland State University, with subcontractor assistance from the University of Minnesota, Gedeon Associates, and Sunpower Inc. has been providing computational and experimental results to support definition of various empirical parameters and "closure" relations needed in defining a thermal, non-equilibrium, macroscopic, porous-media model for use in multi-D Stirling codes for regenerator simulation 33 .…”

Section: An Overview Of the Stirling Enginementioning

confidence: 99%

See 2 more Smart Citations

Effect of Adding a Regenerator to Kornhauser's MIT "Two-Space" (Gas-Spring + Heat Exchanger) Test Rig

Ebiana

Gidugu

2008

6th International Energy Conversion Engineering Conference (IECEC)

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This study employed entropy-based second law post-processing analysis to characterize the various thermodynamic losses inside a 3-space solution domain (gas spring + heat exchanger + regenerator) operating under conditions of oscillating pressure and oscillating flow. The 3-space solution domain is adapted from the 2-space solution domain (gas spring + heat exchanger) in Kornhauser's MIT test rig by modifying the heat exchanger space to include a porous regenerator system. A thermal non-equilibrium model which assumes that the regenerator porous matrix and gas average temperatures can differ by several degrees at a given axial location and time during the cycle is employed. An important and primary objective of this study is the development and application of a thermodynamic loss post-processor to characterize the major thermodynamic losses inside the 3-space model. It is anticipated that the experience gained from thermodynamic loss analysis of the simple 3-space model can be extrapolated to more complex systems like the Stirling engine. It is hoped that successful development of loss post-processors will facilitate the improvement of the optimization capability of Stirling engine analysis codes through better understanding of the heat transfer and power losses. It is also anticipated that the incorporation of a successful thermal nonequilibrium model of the regenerator in Stirling engine CFD analysis codes, will improve our ability to accurately model Stirling regenerators relative to current multi-dimensional thermal-equilibrium porousmedia models.

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Section: Volume-averaged Conservation Of Energy Equationsupporting

confidence: 78%

Section: Non-porous Regions Of the 3-space Domainmentioning

confidence: 99%

Section: An Overview Of the Stirling Enginementioning

confidence: 99%

See 1 more Smart Citation

Effect of Adding a Regenerator to Kornhauser's MIT "Two-Space" (Gas-Spring + Heat Exchanger) Test Rig

Ebiana

Gidugu

2008

6th International Energy Conversion Engineering Conference (IECEC)

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“…The traditional wire mesh type regenerator is most popularly adopted in Stirling engines due to its huge heat transfer area, high convective heat transfer coefficient brought by the cross flow around numerous cylindrical shaped wires, and low axial thermal conductance. However, there are some inherent disadvantages associated with the wire mesh type regenerator [3], such as: (1) the numerous cylinders in cross flow produce flow separation, wakes, eddies and stagnation zones, resulting in high flow friction and considerable thermal dispersion, a loss mechanism that increases apparent axial conduction, damaging power output and engine efficiency; (2) the wire screens have some randomness in stacking, causing locally non-uniform porosity and flow distribution, which might increase axial conduction and damage its thermodynamic performance; (3) the mesh wires are subject to the impact of high-speed high-frequency oscillating flow during operation, so there exists the possibility of working loose or fiber breakage, thus damaging vital engine components; (4) the wire mesh type regenerator also requires long assembly time which tends to increase their cost.…”

Section: Introductionmentioning

confidence: 99%

Analysis of a high performance model Stirling engine with compact porous-sheets heat exchangers

Haramura

Kato

et al. 2014

Energy

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A high performance model Stirling engine, in which the heater, regenerator and cooler as a whole is formed by hundreds of porous metal sheets, is identified for theoretical analysis to facilitate the future scale-up design. The reciprocating flow and heat transfer both in the heat exhcanger and in the full engine is simulated by a dynamic mesh Co mputational Fluid Dynamics (CFD) method, and is validated by analytical solutions and experimental data.An optimization method is also developed to incorporate the entropy generation caused by flow friction and irreversible heat transfer. The results show that relatively high indicated power of 33.4 W is obtained, corresponding to a specific power of 1.88 W/cm 3 and a thermal efficiency of 43.9%, which are attributable to the extremely small flow friction loss and excellent heat transfer characteristics in the regular shaped microchannels, as well as to the compact heat exchanger design that significantly reduces the dead volume. Given the same operating conditions, the optimized porous-sheets regenerator has a significantly lower total loss of available work wh ile maintaining even higher thermal effectiveness in comparison with the optimized conventional wire mesh regenerator.

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“…The present study presents modeling of three-dimensional anisotropic heat transfer and flow resistance properties of an interrupted-plate medium that is made for the purpose of heat absorption. The design idea of the present interrupted-plate heat exchanger (heat-absorbing porous medium) originated from a microfabricated segmented-involute-foil regenerator used for a Stirling engine [1,2]. The segmented-involute-foil structure features layers of thin foils that are stacked perpendicularly to each other.…”

Section: Introductionmentioning

confidence: 99%

Numerical Modeling of Three Dimensional Heat Transfer and Fluid Flow Through Interrupted Plates Using Unit Cell Scale

Zhang¹,

Simon²,

Li³

et al. 2014

Proceedings of the 15th International Heat Transfer Conference

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Interrupted-plate heat exchangers are used as regenerators for absorbing and releasing thermal energy such as in a Compressed Air Energy Storage (CAES) system in which the exchanger absorbs energy to cool the air being compressed. The exchanger features layers of thin plates in stacked arrays. In a given layer, the plates are parallel to one another and parallel to the exchanger axis. Each successive layer is rotated to have its plates perpendicular to the layer below but still parallel to the exchanger axis. As flow passes from one layer to the next, new thermal boundary layers develop, beneficial to effective heat transfer. The interrupted-plate heat exchanger, also seen as a porous medium, demonstrates strong anisotropic behavior when flow approaches the plates other than axially. Pressure drops and heat transfer coefficients are dependent upon the attack angle. Mathematical models for anisotropic pressure drop and heat transfer are proposed based on numerical experiments on a Representative Elementary Volume (REV), which represents a unit cell of the interrupted-plate medium. The anisotropic pressure drop is modeled by the traditionally used Darcy and inertial terms, with the addition of another term representing mixing effects. Heat transfer between fluid and plates is formulated in terms of Nusselt number vs. Reynolds number and mean flow angle. These models can be used when solving the volume-averaged Navier-Stokes equations for global-scale flow through the interrupted-plate arrays, by assuming that the porous medium region is a continuum. The global-scale analysis is used for the design and optimization of the medium.

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A Microfabricated Involute-Foil Regenerator for Stirling Engines

Cited by 9 publications

References 6 publications

Effect of Adding a Regenerator to Kornhauser's MIT "Two-Space" (Gas-Spring + Heat Exchanger) Test Rig

Effect of Adding a Regenerator to Kornhauser's MIT "Two-Space" (Gas-Spring + Heat Exchanger) Test Rig

Analysis of a high performance model Stirling engine with compact porous-sheets heat exchangers

Numerical Modeling of Three Dimensional Heat Transfer and Fluid Flow Through Interrupted Plates Using Unit Cell Scale

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