Cyclic mechanical stability of thermal energy storage media

Abstract

Closing the gap between supply and demand of energy is one of the biggest challenges of our era. In this aspect, thermal energy storage via borehole thermal energy storage (BTES) and sensible heat storage systems has recently emerged as a practical and encouraging alternative in satisfying the energy requirements of household and industrial applications. The majority of these heat energy storage systems are designed as part of the foundation or sub-structure of buildings with load bearing capabilities, hence their mechanical stability should be carefully studied prior to the design and operation phases of the heat storage system. In this study, the cyclic mechanical performance of a commercial cement-based porous heat storage material is analyzed under different amplitudes of cyclic loading and medium temperatures using a recently developed cyclic thermo-mechanical triaxial device. The results show a significant dependence of the cyclic mechanical behavior of the material, such as in the form of cyclic axial and accumulated plastic strains, on the different thermo-mechanical loading schemes.

Effects of drying and shrinkage on the mechanical performance of unsaturated fine/medium- grained soils used as heat storage media

“…Increment times between 12 and 24 hours (depending on the texture of the soils) were allotted for each load/stress step. NA (1) Plastic limit PL (%) NA (1) NA (1) Plasticity index PI (%) NP (2) NP (2) Grain diameter at 10% passing D10 (mm) 0.0085 0.014 ML/CL (4) SM/SC (5) ( 1) : not available, standard criteria not satisfied (2) : non-plastic (3) : effective parameters obtained using Decagon KD2 Pro transient thermal needle probes (4) : silt or clay of low plasticity (5) : silty or clayey sand The specimen deformations were recorded via TRS-0025/TRS-0050 linear transducers with defined electrical ranges of 25 mm/50 mm, independent linearities of 0.2%/0.15% and repeatabilities of 2 μm, respectively. The applied vertical stress and specimen deformation data were monitored and stored with a PC and a data acquisition unit at a data logging interval of 1 minute.…”

“…soils) or solid sensible heat storage systems (e.g. cemented porous media), where heat or cold from solar collectors or other sources of energy is stored for periods of up to several months for later use (Laing et al 2006 [1]; Laing et al 2012 [2]; Hailemariam et al 2019 [3]).…”

Increase the reliability of power supply by using mechanical energy storage devices for low-power consumers

“…Currently, due to the low cost of electricity in the country, it is efficient to use only cheap energy storage devices. Mechanical energy storage devices (MESs) are also cheap energy storage devices at a recognized cost of stored energy [7][8][9].…”