Stirling engine regenerators: How to attain over 95% regenerator effectiveness with sub-regenerators and thermal mass ratios

Nielsen, Anders S.; York, Brayden T.; MacDonald, Brendan D.

doi:10.1016/j.apenergy.2019.113557

Cited by 33 publications

(12 citation statements)

References 40 publications

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“…The ordinate and abscissa of Figure 11 are scaled in logarithmic coordinates. It can be found that the heat transfer coefficient, K , in this paper, is one order of magnitude higher than that of the experimental results (10 4 W/m 2 ·K) 16 based on porous materials, indicating that the PPR has certain feasibility and advantages in SEs. However, it should be noted that the K obtained here does not include the thermal resistance of gas, the actual total heat transfer coefficient of the regenerator will be smaller.…”

Section: Resultscontrasting

confidence: 64%

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Analytical solutions of heat storage and heat transfer performance of parallel‐plate regenerators in Stirling cycle

et al. 2020

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Summary Parallel‐plate regenerators (PPR), with flow resistance lower than traditional wire‐mesh regenerators, can improve the thermal efficiency of Stirling engines (SEs). However, as working frequency or plate thickness increase, the heat cannot penetrate into the plate effectively, resulting only the surface part of the plates to have substantial temperature variation, while the internal part fails to store and exchange heat energy. In order to obtain high performance of PPR, the heat storage efficiency and the heat transfer coefficient, as well as their influential factors, are theoretically studied. Three parameters are found to play an important role, which are working frequency, plate thickness, and thermal diffusivity of materials. Their roles can be represented by a dimensionless parameter as a whole, which is the relative thickness, e. By the critical value of relative thickness, ecr = 2.4, two distinct working conditions can be divided, thermally penetrated condition as e < ecr and thermally non‐penetrated condition as e > ecr. Under thermally penetrated condition, the heat storage efficiency is high, and the heat transfer coefficient is high enough when e > 1.6, while under thermally non‐penetrated condition, the heat storage efficiency is low. In conclusion, by comprehensively considering the heat storage efficiency and heat transfer coefficient, it is recommended that the relative thickness e should be chosen within the range [1.6, 2.4]. And the optimal working frequency, plate thickness, and suitable material can be determined accordingly.

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Section: Resultscontrasting

confidence: 64%

“…Yanaga et al 15 experimentally studied a robust foil regenerator, and the operating frequency was 20 Hz. Nielsen et al 16 experimentally studied a SE with a rotation speed of 180 rpm (3 Hz). In Bulinski's simulation, 17 the maximum rotation speed is 2000 rpm (33.3 Hz).…”

Section: Introductionmentioning

confidence: 99%

Analytical solutions of heat storage and heat transfer performance of parallel‐plate regenerators in Stirling cycle

et al. 2020

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“…The second main component of the dish-Stirling is the Stirling engine, an external combustion engine with two separate cylinders on the expansion side and the compression side. The space between the hot and cold side of the engine is called "regenerator" and acts as a heat recuperator to reduce the work of the compression and expansion of the pistons [22].…”

Section: Introductionmentioning

confidence: 99%

CFD Performance Analysis of a Dish-Stirling System for Microgeneration

2021

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The sustainable transition towards renewable energy sources has become increasingly important nowadays. In this work, a microgeneration energy system was investigated. The system is composed of a solar concentrator system coupled with an alpha-type Stirling engine. The aim was to maximize the production of electrical energy. By imposing a mean value of the direct irradiance on the system, the model developed can obtain the temperature of the fluid contained inside the Stirling engine. The heat exchanger of the microgenerator system was analyzed, focusing on the solar coupling with the engine, with a multiphysical approach (COMSOL v5.3). A real Stirling cycle was implemented using two methods for comparison: the first-order empirical Beale equation and the Schmidt isothermal method. Results demonstrated that a concentrator of 2.4 m in diameter can generate, starting from 800 W/m2 of mean irradiance, a value of electrical energy equal to 0.99 kWe.

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“…These studies have stressed the importance of flow simulation for understanding characteristics of fluid friction. Combined experimental and numerical studies have quantified the pressure drop and heat transfer rate [15]. In addition, effort has been invested to study the design and structural parameters of mesh type regenerators of Stirling cryocoolers [16].…”

Section: Introductionmentioning

confidence: 99%

“…In the literature, studies about regenerators are focused on high and moderate temperature differential Stirling engines. This paper aims to fill out the existing lack about regenerators of low temperature differential engines [19,15]. In this work a theoretical study of regenerators is held, taking into account the pressure drop inside it, heat transfer coefficient, regenerator and engine efficiencies.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Low Temperature Differential Stirling Engine Regenerator Design

Hassani¹,

Boutammachte²,

Hassani³

2020

Adv. sci. technol. eng. syst. j.

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Stirling engines working with relatively low temperature are attractive for the future, especially for applications like water pumping without concentration system and low temperature heat recovery. The present work is the continuation of a series of works on the optimization of this type of machines. The main objective of this paper is to investigate the performance of low temperature differential Stirling engine (LT-SE) regenerator by adopting a theoretical model based on heat transfer and frictional pressure drop correlations. Since the speed and the Reynolds number of this type of machines are low, the correlations concerning pressure drop were validated by comparing the calculated results with experimental measurements on a LT-SE prototype. Based on this model, several calculations were conducted in order to know how LT-SE designers can attain a desired value for regenerator effectiveness. In fact, the effect of six parameters on regenerator performances was investigated. Studied parameters are: engine speed, regenerator volume, regenerator porosity, wires diameter, working fluid type and regenerator fibers arrangement. The effect of these parameters was especially checked on pressure drop, heat transfer coefficient, regenerator and engine efficiencies. Results indicated many designing recommendations for LT-SE having the same power range of our prototype: a regenerator length around Lreg= 1.41 × displacer stroke, a wire diameter around dw= 0.15mm, a porosity around β= 0.75. Results indicated also that the most performant working fluid is Helium.

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Stirling engine regenerators: How to attain over 95% regenerator effectiveness with sub-regenerators and thermal mass ratios

Cited by 33 publications

References 40 publications

Analytical solutions of heat storage and heat transfer performance of parallel‐plate regenerators in Stirling cycle

Analytical solutions of heat storage and heat transfer performance of parallel‐plate regenerators in Stirling cycle

CFD Performance Analysis of a Dish-Stirling System for Microgeneration

Optimization of Low Temperature Differential Stirling Engine Regenerator Design

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