A second-law study on packed bed energy storage systems utilizing phase-change materials

Journal Article · Thu Aug 01 04:00:00 EDT 1991 · Journal of Solar Energy Engineering; (United States)

DOI:https://doi.org/10.1115/1.2930486· OSTI ID:5761887

Adebiyi, G A ^[1]

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1. Mechanical and Nuclear Engineering Dept., Mississippi State Univ., Mississippi State, MS (US)

Thermal modeling of packed bed, thermal energy storage systems has traditionally been limited to first-law considerations. The exceptions include a few second-law studies of sensible heat storage systems and the latent heat storage systems. The cited second-law studies treat the storage and removal processes essentially as batch heating and cooling. The approximation effectively ignores the significant temperature gradient, especially in the axial direction, in the storage medium over a substantial portion of both the storage and removal processes. The results presented in this paper are for a more comprehensive model of the packed bed storage system utilizing encapsulated phase-change materials. The fundamental equations for the system are similar to those of Schumann, except that a transient conduction equation is included for intraparticle conduction in each pellet. The equations are solved numerically, and the media temperatures obtained are used for the determination of the exergy (or availability) disposition in complete storage-removal cycles. One major conclusion of the study from both the first-law and second-law perspectives is that the principal advantage in the use of phase-change storage material is the enhanced storage capacity, compared with the same size of packed bed utilizing a sensible heat storage material. Thermodynamically, however, it does not appear that the system employing phase-change storage material will always, or necessarily, be superior to that using a sensible heat-storage material. The latter conclusion is reached only on the basis of the second-law evaluation.

• OSTI ID: 5761887
• Journal Information: Journal of Solar Energy Engineering; (United States), Journal Name: Journal of Solar Energy Engineering; (United States) Vol. 113:3; ISSN 0199-6231; ISSN JSEED
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
250600* -- Energy Storage-- Thermal
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
CONSERVATION LAWS
COOLING
ENERGY
EQUIPMENT
EXERGY
HEATING
MATERIALS
MATHEMATICAL MODELS
PACKED BEDS
PHASE CHANGE MATERIALS
PHYSICAL PROPERTIES
THERMAL CONDUCTIVITY
THERMAL ENERGY STORAGE EQUIPMENT
THERMODYNAMIC PROPERTIES