An exergy analysis of sensible and latent heat storage

Bjurström, Henrik; Carlsson, Bo

doi:10.1016/0198-7593(85)90081-5

Cited by 79 publications

(32 citation statements)

References 6 publications

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“…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). This paper focuses specifically on the energy and exergy contents of stratified storages.…”

Section: Exergy Analysis Thermal Storage and Stratificationmentioning

confidence: 99%

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

Rosen

Tang

Dinçer

2004

Int. J. Energy Res.

102

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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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Section: Exergy Analysis Thermal Storage and Stratificationmentioning

confidence: 99%

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

Rosen

Tang

Dinçer

2004

Int. J. Energy Res.

102

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“…Relations were derived for the amount of exergy stored in the PCM and final temperature of the storage material. The current work uses the equations derived by Bjurstrom and Carlsson (1985) for analysis of the storage system. The main assumptions used in the analysis are as follows.…”

Section: Phase Change Materialsmentioning

confidence: 99%

“…The procedure used for calculation of the final storage temperature and the amount of stored exergy is found from equations given by Bjurstrom and Carlsson (1985). The procedure used is detailed as follows.…”

Section: Phase Change Materialsmentioning

confidence: 99%

“…For the calculation of exergy terms, this assumption is not fully validated for water. Exergy analysis for PCM was also done by Bjurstrom and Carlsson (1985). Relations were derived for the amount of exergy stored in the PCM and final temperature of the storage material.…”

Section: Phase Change Materialsmentioning

confidence: 99%

“…According to Bejan et al (1996) an optimal system which a designer can develop with the least irreversibility is based on the minimization of entropy generation. The application of second-law analysis for studying latent heat storage was studied by Bjurstrom and Carlsson (1985) and Adebiyi and Russell (1987), and was later added to by Bejan (1996). A study was done by El-Dessouky and Al-Juwayhel (1997) which investigated the effect of different variables on the entropy generation number defined by Bejan et al (1996).…”

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confidence: 99%

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Thermodynamic and thermoeconomic analysis of combined geothermal space heating and thermal storage using phase change materials

Chauhan

Ragnarsson

2015

Geoth. Energ. Sci.

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Abstract. The present work discusses the utilization of phase change materials for energy storage in geothermal space heating systems. Thermodynamics and thermoeconomics of the combined heating and thermal storing system were studied to show the scope of energy storage and cost savings. A computational model of the combined space heating and thermal storage system was developed and used to perform thermodynamic studies of the heat storage process and heating system efficiency at different times and ambient temperatures. The basis for these studies is daily variations in heating demand that is higher during the night than during the day. The results show the scope of the utilization of phase change material for low ambient temperature conditions. Under proper conditions a sufficient amount of exergy is stored during the charging period at a low ambient temperature to fulfill the daytime heat load requirement. Under these conditions the cost flow rate of exergy storage is found to be lower than the radiator heating cost flow rate. Thus, the use of exergy storage at low ambient temperatures for heating at higher ambient temperatures makes a significant contribution to cost savings.

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Exergy analysis of latent heat storage systems with sensible heating and subcooling of PCM

Ancha¹,

Ramesh²

1998

Int. J. Energy Res.

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The effect of sensible heating of the phase‐change material (PCM) before melting and subcooling after solidification, on the performance of the latent heat storage system (LHSS), is studied in terms of first‐ and second‐law efficiencies for the overall charge–discharge cycle. The external heat transfer irreversibilities on account of the interaction between the heat transfer fluid and the storage element are characterized and the optimum phase‐change temperature for maximum second‐law efficiency is studied. The performance of the LHSS operation is assessed with and without sensible heating before melting and subcooling after solidification. It is observed that the optimum phase‐change temperature is higher, and, the overall second‐law efficiency is greater for LHSS with sensible heating and subcooling beyond a certain phase‐change temperature compared to latent heat storage alone. In addition, the first‐law overall efficiency is found to exhibit a minimum and a pre‐heated discharge stream is shown to result in a substantial improvement of the second‐law efficiency. © 1998 John Wiley & Sons, Ltd.

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An exergy analysis of sensible and latent heat storage

Cited by 79 publications

References 6 publications

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

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

Thermodynamic and thermoeconomic analysis of combined geothermal space heating and thermal storage using phase change materials

Exergy analysis of latent heat storage systems with sensible heating and subcooling of PCM

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