This study is focused on the simulation and optimization of packed-bed solar thermal energy storage by using sand as a storage material and hot-water is used as a heat transfer fluid and storage as *** analysis has be...
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This study is focused on the simulation and optimization of packed-bed solar thermal energy storage by using sand as a storage material and hot-water is used as a heat transfer fluid and storage as *** analysis has been done by using the COMSOL multi-physics software and used to compute an optimization charging time of the *** that control this optimization are storage height,storage diameter,heat transfer fluid flow rate,and sand bed particle *** result of COMSOL multi-physics optimized thermal storage has been validated with Taguchi ***,the optimized parameters of storage are:storage height of 1.4m,storage diameter of 0.4 m,flow rate of 0.02 kg/s,and sand particle size 12 *** these parameters,the storage diameter result is the highest influenced optimized parameter of the thermal storage fromthe ANOVA *** nominal packed bed thermal storage,the charging time needed to attain about 520 K temperature is more than 3500 s,while it needs only about 2000 s for the optimized storage which is very significant *** charging energy efficiency of the optimized is greater than the nominal and previous concrete-based storage by 13.7%,and 13.1%,respectively in the charging time of 2700 s.
Cross-linked Polyethylene (XLPE) cables are widely used for medium voltage underground cables these days. However, void and impurity defects have been a major reason for the failure of cable insulations as these defec...
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ISBN:
(纸本)9781509012770
Cross-linked Polyethylene (XLPE) cables are widely used for medium voltage underground cables these days. However, void and impurity defects have been a major reason for the failure of cable insulations as these defects induce internal discharges and cause a significant change in the dielectric properties of the insulation. The objective of this paper is to investigate the effect of nanofillers in inhibiting water tree propagation. This is done by calculating electric stress at different points in unfilled XLPE and XLPE nanocomposite. For that various analyses are conducted viz. study and comparison of the electric field stress distribution in unfilled XLPE with the presence of water voids with and without nanofiller. It is found that the field effect is more at the edges of the ellipse shaped water voids. Water voids which experience the maximum electric field, form channels and lead to break down. Addition of nanofillers delays the path of electric field distribution and increases the breakdown strength. In this study four types of nanofillers are considered with different weight percentage loading. Electric field distribution has been varying for different weight percentage of nanofillers. Due to the high interface/volume ratio in nanocomposites, it is found that nanocomposites have higher resistance to water tree growth and scattering in the interfacial region inhibits tree growth.
Microelectromechanical Systems (MEMS) has found vast applications in today's world. Many applications in the field of aerospace, biomedicine, laser scanning displays and biomedical imaging systems are realized usi...
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ISBN:
(纸本)9781479960859
Microelectromechanical Systems (MEMS) has found vast applications in today's world. Many applications in the field of aerospace, biomedicine, laser scanning displays and biomedical imaging systems are realized using MEMS technology. Pyroelectric materials show temperature dependent spontaneous electrical polarization converting thermal energy to electrical energy. In this paper, a self actuating MEMS cantilever for pyroelectric energy conversion is designed using COMSOL Multiphysics software. The energy conversion mechanism and response of a MEMS cantilever with PVDF as pyroelectric material is studied. The base materials used include Silicon Dioxide, Silicon, Aluminum, Polyvinylidine Fluoride (PVDF).
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