Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7936510 | Solar Energy | 2016 | 12 Pages |
Abstract
This paper presents the performance assessment of stratified sensible thermal energy stores (SSTES) on the basis of the normalized exergy efficiency, ηâ¾x. Assessments based on ηâ¾x provide comparisons with performances of both the perfectly stratified and the fully mixed stores, which offer the best and worst performances, respectively. This is in contrast with energy and exergy efficiencies, which compare SSTES with only the perfectly stratified store. A dimensionless unsteady axisymmetric model of vertical cylindrical SSTES was implemented using a finite volume numerical scheme. The effect of some significant parameters on SSTES performance were considered by performing computations for aspect ratios (AR) between 1 and 4, Peclet number (PeD) varying from 5Ã103 to 100Ã103, Richardson number (Ri) varying from 10 to 104, and overall heat loss coefficients (U) varying from 0 to 100 W mâ2 Kâ1. ηâ¾x increases with PeD, Ri and AR, with the most significant increases occurring at low values of these parameters, and appreciable increases are no longer obtained beyond PeDâ30Ã103, Riâ103 and ARâ3. ηâ¾x also falls monotonically as the U values increase.
Keywords
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Physical Sciences and Engineering
Energy
Renewable Energy, Sustainability and the Environment
Authors
H.O. Njoku, O.V. Ekechukwu, S.O. Onyegegbu,