Investigation on the pressure drop characteristics of cryocooler regenerators under oscillating flow and pulsating pressure conditions

Choi, Sungryel; Nam, Kwanwoo; Jeong, Sangkwon

doi:10.1016/j.cryogenics.2003.11.006

Cited by 31 publications

(18 citation statements)

References 7 publications

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“…These average values were found to be larger than the corresponding steady-flow values by a factor of about one and one-half to two. Experimental results for the average Fanning friction factor in oscillating flow were presented by Nam et al [27][28][29]. Their data over the range Re % 2090 are correlated by the equation f osc ¼ 39:52=Re þ 0:01.…”

Section: Discussionmentioning

confidence: 95%

Optimal regenerator performance in Stirling engines

Boer

2009

Int. J. Energy Res.

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SUMMARYThe key component of a Stirling engine is its regenerative heat exchanger. This device is subject to losses due to dissipation arising from the flow through the regenerator as well as due to imperfect heat transfer between the regenerator material and the gas. The magnitudes of these losses are characterized by the Stanton number St and the Fanning friction factor f , respectively. Using available data for the ratio St=f , results are found for the Carnot efficiency and the power output of the regenerator. They depend on the conductance and on the ratio of pressures at the two sides of the regenerator. Optimum results for efficiency and power output of the regenerator are derived in the limit of zero Mach number. The results are applied to the Stirling engine. The efficiency and the power output of the engine are found for given amplitude of the compression piston. Optimization with respect to regenerator conductance and piston phase angle leads to a maximum possible value of the power output. Under optimal conditions, the Carnot efficiency just below this maximum is close to 100%.

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Section: Discussionmentioning

confidence: 95%

Optimal regenerator performance in Stirling engines

Boer

2009

Int. J. Energy Res.

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“…The steady flow model [8,9] results in major discrepancies between the predicted results and the experimental data. Recently, a new oscillating flow model [10,11] based on two non-dimensional parameters has been developed to overcome inaccuracy of the conventional flow model based on steady flow friction factor. A revised correlation of the friction factor has also been proposed [12] to improve the oscillating flow model of regenerator at cryogenic temperature by introducing the Valensi number and the expansion parameters.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of oscillating flow characteristics of cryocooler regenerator at low temperatures

Shen

2009

Front. Energy Power Eng. China

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A brief review is presented on previous experimental results and correlations on the friction factor of cryocooler regenerators operating at oscillating flow and pulsating pressure conditions, for different mesh sizes of packed woven screens, focusing on the effects of different operating frequencies ranging from 20 to 80 Hz, at room and cryogenic temperatures. A comparison of the friction factor data with those of other studies is presented to clarify the reason for the difference. Finally, a new oscillating flow correlation of regenerators, in terms of several nondimensional parameters, is discussed and compared.

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“…Re = d 2 / is defined as the kinematic Reynolds number, following . It is also sometimes referred to as the Valensi number (Richardson, 1963 andChoi et al, 2004), or the non-dimensional frequency parameter (Berger and Wille, 1972). In thermoacoustics, the viscous penetration depth, , is often used as an alternative indication of the acoustic oscillation frequency.…”

Section: Normalisationmentioning

confidence: 99%

Oscillatory flow at the end of parallel-plate stacks: phenomenological and similarity analysis

Mao

Jaworski

2010

Fluid Dyn. Res.

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This paper addresses the physics of the oscillatory flow in the vicinity of a series of parallel plates forming geometrically identical channels. This type of flow is particularly relevant to thermoacoustic engines and refrigerators, where a reciprocating flow is responsible for the desirable energy transfer, but it is also of interest to general fluid mechanics of oscillatory flows past bluff bodies. In this paper the physics of an acoustically induced flow past a series of plates in an isothermal condition is studied in detail using the data provided by PIV imaging. Particular attention is given to the analysis of the wake flow during the ejection part of the flow cycle, where either closed re-circulating vortices or alternating vortex shedding can be observed. This is followed by a similarity analysis of the governing Navier-Stokes equations in order to derive the similarity criteria governing the wake flow behaviour. To this end, similarity numbers including two types of Reynolds number, Keulegan-Carpenter number and a non-dimensional stack configuration parameter, d/h are considered and their influence on the phenomena discussed.

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Investigation on the pressure drop characteristics of cryocooler regenerators under oscillating flow and pulsating pressure conditions

Cited by 31 publications

References 7 publications

Optimal regenerator performance in Stirling engines

Optimal regenerator performance in Stirling engines

Comparative study of oscillating flow characteristics of cryocooler regenerator at low temperatures

Oscillatory flow at the end of parallel-plate stacks: phenomenological and similarity analysis

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