• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.787-794
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• 1992

To predict performances of Stirling Engines, a second-order analysis method has been developed. The present method which is based on the approximate analytical solution to the Ideal Adiabatic Model includes major loss mechanisms due to finite heat transfer and flow friction. Comparison of calculated results with previously reported study for a specific engine shows reasonable agreements and a possibility of being used for basic designs. Also, predicted performances with repect to engine speeds are consistent with experimental data in trend. To improve the prediction capability of this method, it is needed that not only additional losses should be taken into account, but also fundamental characteristics of oscillating flow and heat transfer should be better understood.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.794-799
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• 2001

The simulation analyses of a solar power system with monolithic concentrator by using a stirling engine are carried out to predict the system performance in four test sites. The site has different intensities and distributions of direct solar radiation respectively. Seoul, Pusan and Cheju in Korea, and Naha in Japan are selected as test sites. To accomplish the same demand of a 25 kW output that the power level of a system has, it needs to take the matching of collector/receiver with engine/generator systems. In such a case, also, the size of the collector is sometimes adjusted. In this study, the diameter of the collector is decided by using the solar radiation of design point, which is defined as the sum of average and standard deviation $\sigma$ of maximum direct solar radiation distribution for a day during a year in the respective test site. It is found that the average power output during the system operating time in the case of slope error ${\sigma}_s=2.5$ is within the range of 9 to 13 kW.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.4
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• pp.1385-1394
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• 1996

A theoretical analysis was performed on the heat transfer by laminar oscillating flow in a simplified heat exchanger of a Stirling cycle machine and the results were compared with the experiment of Hwang. In the analysis the general solution to the temperature field obtained by Lee et. al was applied and extended to a more realistic situation. The results show that the heat transfer is influenced by the ratio of the swept distance of the fluid to the length of the heat exchanger as well as the oscillation frequency. This is well consistent with the result of Hwang's experiment. It is also revealed that there exist three distinct regimes having different heat transfer mechanisms. Through the scale analysis the main parameters governing the heat transfer in each regime are reduced and the dependency of the heat transfer on the parameters are examined.

• Journal of Biosystems Engineering
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• v.30 no.4 s.111
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• pp.195-201
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• 2005

The output of Stirling engine is influenced by the regenerator effectiveness. The regenerator effectiveness is influenced by heat transfer and flow friction loss of the regenerator matrix. In this paper, in order to provide a basic data for the design of regenerator matrix, characteristics of heat transfer and flow friction loss were investigated by a packed method of matrix in the oscillating flow as the same condition of operation in a Stirling engine. As matrices, several kinds of combined wire screen meshes were used. The results are summarized as follows; The packed meshes with high mesh no. in the side of heater part of regenerator showed effective than the packed meshes with low mesh no. in the side of cooler part of regenerator. The temperature difference and pressure drop of the regenerator were not made by the specific surface area of wire screen meshes but by the minimum free-flow area to the total frontal area. Among the No. 150 single screen meshes, 200-60 combined meshes, the 200-150-100 combined meshes showed the highest in effectiveness.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.248-257
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• 2016

Recently, researches on the free-piston Stirling engines(FPSEs) are actively investigated. FPSEs have merits in its light weight, simple structure, and little need for maintenance, thus becoming a promising solution for the power conversion of renewable energy and waste heat recycle. This paper presents the methodology that estimates damping coefficients using analytical models of linear and nonlinear dynamics for FPSEs, and validates the methodology by comparing with existing experimental results. The analysis model predicts an operable range of linear damping coefficients forming limit cycles by using the root locus, and time responses obtained by numerical integration determines nonlinear damping coefficients. The model predictions are compared with experimental results of the well-known FPSE B-10B. We also investigate the damping characteristics regarding heater temperatures and power piston motions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.656-663
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• 1990

To investigate the optimum design conditions of Stirling Engines at the preliminary design stage, comparative study between adoabatoc analysis based on an approximate analytical solution to the Ideal Adiabatic Model and the existing isothermal analysis has been carried out. The optimum phase angle obtained from adiabatic analysis to achieve the maximum work with given combination of design parameters is greater than that from isothermal analysis, while the optimum swept volume ratio is smaller. Effect of variation in the temperature ratio on the work parameter is proved to be stronger in adiabatic analysis. On the contrary, the work parameter by adiabatic analysis is less sensitive to a change in the dead volume ratio. Especially in adiabatic analysis there exists the optimum dead volume ratio maximizing the work parameter, which may provide a lower limit of it. Considering that the adiabatic model is more reasonable, signifiant differences between two methods lead to the conclusion that adiabatic analysis is preferable to isothermal one for the preliminary design of Stirling Engines.

• Journal of computational fluids engineering
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• v.16 no.3
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• pp.88-94
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• 2011

The availability of the thermal energy has been deeply recognized recently to encourage the cascade usage of thermal energy from combustion. Within the framework, a 1 kW class Stirling engine based cogeneration system has been proposed for a unit of a distributed energy system. The capacity has been designed to be adequate for the domestic usage, which requires high compactness as well as low emission and noise. To develop a highly efficient system with satisfying these requirements, a premixed slot type short flame burner has been proposed and a series of numerical simulation has been performed to establish a design tool for the combustion chamber. The thermal radiation model has been found to highly affect the computational results and a proper resolution to analyze the heat transfer characteristics of the high temperature heat exchanger. Finally, the combustion characteristics of the premixed flame with the metal fiber type burner has been studied.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.8
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• pp.545-552
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• 2017

In this research, numerical analysis was carried out on novel and existing fins, adjusted in terms of factors such as length, spacing, and angle, of a high-temperature heat exchanger for a 1 kW class Stirling engine, designed as a prime mover for a domestic cogeneration system. The performance improvement as a result of shape optimization was confirmed with numerical analysis by including the air preheater, which was not considered during optimization. However, a negative heat flux was observed in the cylinder head portion. This phenomenon was clarified by analyzing the exhaust gas and wall surface temperature of the combustion chamber. Furthermore, assuming an ideal cycle, the effects of heat transfer enhancement on the thermodynamic cycle and system performance were predicted.

• Kyungpook Mathematical Journal
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• v.64 no.1
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• pp.133-159
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• 2024

In a previous work we studied generalized Stirling numbers of the second kind S^{(a₂,b₂,p₂)}_a1,b1 (p₁, k), where a₁, a₂, b₁, b₂ are given complex numbers, a₁, a₂ ≠ 0, and p₁, p₂ are non-negative integers given. In this work we use these generalized Stirling numbers to define Bernoulli polynomials in two variables B_p1,p2 (x₁, x₂), and Euler polynomials in two variables E_p1p2 (x₁, x₂). By using results for S^{(1,x₂,p₂)}_1,x1 (p₁, k), we obtain generalizations, to the bivariate case, of some well-known properties from the standard case, as addition formulas, difference equations and sums of powers. We obtain some identities for bivariate Bernoulli and Euler polynomials, and some generalizations, to the bivariate case, of several known identities for Bernoulli and Euler numbers and polynomials of the standard case.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.475-482
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• 2014

This paper presents the results of an experimental feasibility study on low-temperature differential Stirling engines with water spray heat transfer. The water spray enhances the efficiency of the heat transfer from heat sources to the engine and reduces the performance degeneration due to the dead volumes of conventional heat exchangers. A test Stirling engine was developed and an experiment was conducted to determine the characteristics for the initial start-up, steady-state operation, and power output for various flow rates and temperatures of hot supply water. The test results showed that larger flow rates led to reductions in the minimum working temperature of the hot water at start-up. During a series of steady-state operations, higher flow rates and temperatures increased the working speed. Furthermore, the work per cycle and power output were also increased. Eventually, the test Stirling engine had a power level of 0.05 W. Based on this, further research will be conducted to obtain a higher power output and investigate various applications.