Application of Discriminated Dimensional Analysis to the Kinematic Stirling Engine

Prieto, Jesús-Ignacio; Fano, José María Marcos; Dı́az, R.; González, Miguel A.

doi:10.1243/pime_proc_1994_208_137_02

Cited by 11 publications

(20 citation statements)

References 10 publications

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“…To consider the influence of , the mean pressure values of 4, 5, 6 and 6.9 bar were also considered. The CFD results are listed in Table 5 From equations (6) and (14), The second type of diagram is probably more used because the points of maximum power and efficiency are easy to identify. Figure 13(b) shows that the points of maximum indicated power correspond to velocities that increase slightly with the mean pressure, as corresponds to the positive exponent of in equation (8).…”

Section: Nominal Operating Characteristicsmentioning

confidence: 99%

“…The University of Oviedo and the technological research centre IK4-Tekniker Foundation have developed a Stirling solar micro power unit, designed using similarity criteria previously introduced by independent authors. The scaling of indicated power has been justified by detailed analyses of the physical and geometric variables influencing the thermodynamic performance of the gas circuit [9][10][11][12][13][14][15], while the analysis of mechanical losses has allowed this procedure to be extended for brake power scaling [16][17][18]. The approach is based not only on experimental data but also on theoretical concepts and has proven its usefulness both for analysis and design purposes [19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

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Experimental correlations and CFD model of a non-tubular heater for a Stirling solar engine micro-cogeneration unit

García

Suárez-López

Blanco

et al. 2019

Applied Thermal Engineering

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A non-tubular heat exchanger for use in a Stirling solar engine micro-CHP unit is being developed by the University of Oviedo and the technological research centre IK4-Tekniker Foundation. In this article, the correlations for the friction factor and Stanton number previously obtained under steady flow conditions are revised and the corresponding experimental data are used to validate a CFD model of the heater. The CFD model enables the estimation of variables whose measurement is practically unviable, as is the case for the spatial distribution of wall and gas temperatures. The conceptual importance of the heater wall temperature for the analysis and design of Stirling engines is highlighted, and some limitations that are inherent in the non-tubular geometry are observed. The CFD model provides a basis for the analysis of engine operation and for subsequent geometric optimization of the heater. To evaluate the engine power and efficiency forecasts under nominal operating conditions, the CFD model is used to complement the analysis procedure based on experimental data from benchmark engines with very different geometries and operating variables. The results predict that the engine will be able to exceed the targets set in the preliminary design stage.

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Section: Nominal Operating Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental correlations and CFD model of a non-tubular heater for a Stirling solar engine micro-cogeneration unit

García

Suárez-López

Blanco

et al. 2019

Applied Thermal Engineering

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show abstract

“…Secondly, even when the list of relevant variables is correctly formulated, the classical application of pi theorem does not always provide the independent dimensionless groups unless discrimination is taken into account in the nondimensionalization procedure. The concept of discrimination as an extension of dimensional analysis is introduced by Madrid and Alhama [10] in the field of convective heat transfer and used by these and other authors for the derivation of the correct dimensionless groups [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

On the Nondimensionalization Process in Complex Problems: Application to Natural Convection in Anisotropic Porous Media

Alhama

Cánovas

Alhama

2014

Mathematical Problems in Engineering

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The nondimensionalization of the equations governing a given problem is a direct, relatively easy, and low-cost way to provide interesting information, the dimensionless groups that rule the problem and define its final patterns of solution. In complex problems, however, this technique frequently does not provide the precise and complete set of monomials we are looking for. The use of discrimination in the process of nondimensionalization, the detailed application of which is explained in this paper, always leads to a minimum set of parameters, which, separately, determine the solution of the problems. In addition, the physical meaning and order of magnitude of these discriminated monomials are also provided by the discrimination. The technique is applied to the coupled problem of natural convection between horizontal plates heated from below, containing an anisotropic porous medium.

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“…The concept of quasi-static simulation was introduced by Prieto et al [6] to designate the coecient 0 , which represents the theoretical prediction for the engine con®guration assuming an ideal cycle, i.e. without any losses caused by thermal or mechanical irreversibilities.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, equation (6) ®rst introduced a relation between such quasi-static predictions and the dimensionless speeds corresponding to the maximum indicated power values. This relation is computed through a losses coecient È that does not depend on the engine speed [6]:…”

Section: Introductionmentioning

confidence: 99%

A new equation representing the performance of kinematic Stirling engines

Prieto

González

et al. 2000

Proceedings of the Institution of Mechanical Engineers, Part C:

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Previous work carried out for the last eight years resulted in the proposal of a complete system of dimensionless groups in order to represent the performance of dierent kinematic Stirling engine con®gurations. When looking for experimental support for the proposed model, some differences between the performances of several prototypes were observed. In this paper an equation is introduced to be applied to all known kinematic engines and to their whole range of performance. The coecients appearing in this equation can be computed from temperature and geometrical dimensionless ratios and from experimental measurements at the maximum indicated power operating point. The meaning of those coecients is interpreted and their usefulness to provide an engine performance overview is shown. The quasi-static simulation and the characteristic Mach number at the maximum indicated power operating point appear to be interesting criteria in order to evaluate the performance of prototypes. NOTATION a, b dimensionless coecients of the friction factor A xx cross-sectional area (m 2 ) C f friction factor L length (m) n s engine speed (r/s) N B Beale number N MA characteristic Mach number n s V 1a3 E a RT C p N p characteristic pressure number p m V 1a3 E a " RT C p N SG N MA N re local instantaneous Reynolds number N RE characteristic Reynolds number p m V 2a3 E n s a "RT C N SG N 2 MA N SG characteristic Stirling number p m a"n s N TCR characteristic regenerator thermal capacity number & r c r T C ap m N W West number N characteristic regenerator thermal diusivity number r aV 1a3 E RT C p p m mean pressure (Pa) P B brake power (W) P ind indicated power (W) r crank radius (m) r hx hydraulic radius (m) R speci®c gas constant (J/kg K) T temperature (K) u local instantaneous¯uid velocity (m/s) V swept volume (m 3 ) V dx dead volume (m 3 ), Y 1 dimensionless coecients of the mechanical losses of the indicated power r regenerator material thermal diusivity (m 2 /s) xx dimensionless cross-sectional area parameter A xx raV E adiabatic coecient 1 , F F F , n angles and other dimensionless parameters of the drive mechanism, normalized by the crank radius dimensionless indicated power P ind ap m V E n s B dimensionless brake power P B ap m V E n s mec dimensionless mechanical losses of the indicated power À B ÁP ind ap m V E n s mec mechanical eciency B a swept volume ratio V C aV E ! dimensionless parameter as de®ned in text ! hx dimensionless hydraulic radius parameter r hx ar heThe MS was

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Application of Discriminated Dimensional Analysis to the Kinematic Stirling Engine

Cited by 11 publications

References 10 publications

Experimental correlations and CFD model of a non-tubular heater for a Stirling solar engine micro-cogeneration unit

Experimental correlations and CFD model of a non-tubular heater for a Stirling solar engine micro-cogeneration unit

On the Nondimensionalization Process in Complex Problems: Application to Natural Convection in Anisotropic Porous Media

A new equation representing the performance of kinematic Stirling engines

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