The Evaluation of Thermal Stratification by Exergy

Hahne, Ε.; Kübler, R.; Kallweit, Jörg

doi:10.1007/978-94-009-2350-8_20

Cited by 11 publications

(7 citation statements)

References 2 publications

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“…The present authors, for instance, have examined exergy analysis methodologies in detail (Rosen, 1999b), and applied them to industrial systems (Rosen and Horazak, 1995), countries (Rosen and Dincer, 1997a) and environmental impact assessments Dincer, 1997b, 1999b), as well as TES (Dincer, 1999;Dincer et al, 1997;Gunnewiek et al, 1993;Rosen, 1991Rosen, , 1992Rosen, , 1999aRosen and Dincer, 1999a;Rosen and Hooper, 1994;Rosen et al, 1988Rosen et al, , 1999Rosen et al, , 2000Rosen and Tang, 1997). Only a limited number of TES exergy analyses have been performed (Bejan, 1978(Bejan, , 1995Badar et al, 1993;Bascetincelik et al, 1998;Bjurstrom and Carlsson, 1985;Hahne et al, 1989;Krane, 1987;Krane and Krane, 1991;Mathiprakasam and Beeson, 1983;Moran and Keyhani, 1982;Rosenblad, 1985).…”

Section: Introductionmentioning

confidence: 99%

Exergy methods for assessing and comparing thermal storage systems

Rosen

Dinçer

2003

Int. J. Energy Res.

141

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SUMMARYThe usefulness is illustrated of exergy analysis in providing insights into the behaviour and performance of thermal energy storage (TES) systems, by providing an overview of many investigations by the authors on this topic. Several topics are covered. First, exergy analysis is described and thermodynamic considerations in TES evaluation are discussed. Then, the exergy analysis of a closed TES system is detailed, highlighting two critical factors: appropriate TES efficiency measures and the importance of temperature in TES evaluations. Next, applications of exergy to several TESs are discussed, including aquifer systems, stratified storages and cold TES. Finally, uses of exergy methods in optimization and design are illustrated by determining optimal discharge periods.

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Section: Introductionmentioning

confidence: 99%

Exergy methods for assessing and comparing thermal storage systems

Rosen

Dinçer

2003

Int. J. Energy Res.

141

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“…The present work applies exergy analysis to thermal-storage assessment and is, in part, directed towards developing alternative exergy-based performance measures for stratified thermal storage systems in an effort to render exergy methods more conveniently available for design engineers and thus to encourage their use. Other applications of exergy analysis to thermal storage systems have been discussed elsewhere (Beckman and Gilli, 1984;Hahne et al, 1989;Krane and Krane, 1991;Bejan. 1982;Moran and Keyhani, 1982;De Lucia and Bejan, 1990;Bjurstrom and Carlsson, 1985;Krane, 1987).…”

Section: Exergy Analysis Thermal Storage and Stratificationmentioning

confidence: 98%

“…The assessment of the effectiveness of a stratification process can be made using exergy methods (Hahne et al, 1989;Krane and Krane, 1991;Zurigat et al, 1991;Abu-Hamdan, 1992;Rosen and Hooper, 1996;. In fact, energy analysis generally does not allow appropriate quantified measures of the benefits of stratification to be developed, while exergy analysis does.…”

Section: Introductionmentioning

confidence: 99%

Effect of stratification on energy and exergy capacities in thermal storage systems

Rosen

Tang

Dinçer

2004

Int. J. Energy Res.

101

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SUMMARYThe increase in exergy storage capacity that is attained in thermal storages through stratification is assessed. A design-oriented temperature-distribution model for vertically stratified thermal storages that facilitates the evaluation of storage energy and exergy contents is utilized. The paper is directed towards demonstrating the thermodynamic benefits achieved through stratification, and increasing the utilization of exergy-based performance measures for stratified thermal storages. A wide range of realistic storage-fluid temperature profiles is considered, and for each the relative increase in exergy content of the stratified storage compared to the same storage when it is fully mixed is evaluated. The results indicate that, for all temperature profiles considered, the exergy storage capacity of a thermal storage increases when it is stratified, and increases as the degree of stratification, as represented through greater and sharper spatial temperature variations, increases. Furthermore, the percentage increase in exergy capacity is greatest for storages at temperatures near to the environment temperature, and decreases as the mean storage temperature diverges from the environment temperature (to either higher or lower temperatures). It is concluded that (i) the use of stratification in thermal storage designs should be considered as it increases the exergy storage capacity of a thermal storage and (ii) exergy analysis should be applied in the analysis and comparison of stratified thermal storage systems.

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“…In the case of TES systems, which do not in general operate at steady state, the exergy entering is stored, or exits, or is destroyed due to irreversibilities. Exergy analysis and its implications in TES and other applications are discussed in further detail elsewhere (Bejan, 1982;Bjurstrom and Carlsson, 1985;Krane, 1987;Hahne et al, 1989;Rosen and Hooper, 1990;Rosen, 1992;Gunnewiek et al, 1993;Moran and Shapiro, 1995;Rosen and Dincer, 1997).…”

Section: Introductionmentioning

confidence: 98%