Thermo-mechanical parametric analysis of packed-bed thermocline energy storage tanks

Abstract

© 2016. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/A packed-bed thermocline tank represents a proved cheaper thermal energy storage for concentrated solar power plants compared with the commonly-built two-tank system. However, its implementation has been stopped mainly due to the vessel’s thermal ratcheting concern, which would compromise its structural integrity. In order to have a better understanding of the commercial viability of thermocline approach, regarding energetic effectiveness and structural reliability, a new numerical simulation platform has been developed. The model dynamically solves and couples all the significant components of the subsystem, being able to evaluate its thermal and mechanical response over plant normal operation. The filler material is considered as a cohesionless bulk solid with thermal expansion. For the stresses on the tank wall the general thermoelastic theory is used. First, the numerical model is validated with the Solar One thermocline case, and then a parametric analysis is carried out by settling this storage technology in two real plants with a temperature rise of 100 °C and 275 °C. The numerical results show a better storage performance together with the lowest temperature difference, but both options achieve suitable structural factors of safety with a proper design.Peer ReviewedPostprint (author's final draft

Current, Projected Performance and Costs of Thermal Energy Storage

“…This type of weakness is under evaluation and could be overcome using bricks as well as a suitable design of the tank [40]. Recently, it is possible to find on the market a grid-connected molten salt storage capacity for CSP larger than 30 GWth [41]. Solid storage materials, such as brick, concrete, and ceramic materials, are also employed in SH-TES systems for low, medium, and high temperatures.…”

“…Over the past few decades, there have been numerous studies on eutectics (inorganic and organic compounds) as a thermal energy storage medium. Several techniques are available or under development for improving heat transmission, including high thermal conductivity [41,42] (Figure 2). During phase changes, paraffin also undergoes large volume changes and has low thermal conductivity.…”

“…The most promising reaction is the gas-solid one. Some gas-liquid and gas-gas reactions can be exploited; however, weak chemical bonds are involved, and temperatures are lower (20-200 • C) in these cases, as well as the chemisorption process [41,42]. Among these, "sorption" TES methods are very affordable for building applications; their heat density is in the range of 200 kWh/m 3 for zeolite [45,46] and 230 kWh/m 3 for silica gel [47].…”

“…Although the seasonal storage facilities have been developed in cold climates (northern Europe), the south European latitude has an especially favourable seasonal storage for solar systems associated with high temperatures, as summer solar irradiance is about three times as great as winter solar irradiance [33][34][35][36][37][38]. As previously mentioned, the storage time is a relevant property of TES; therefore, a classification based on both short-and long-term storage is presented in Figure 1 [39][40][41].…”

Energia termosolar: uma revisão de literatura

“…A utilização de tanques termoclinos de armazenamento simultâneo de calor sensível e latente é mais barato que a alternativa clássica de dois tanques, mas sua implantação enfrenta dificuldades com sua integridade estrutural. González et al (2016) desenvolveram uma plataforma de simulação numérica capaz de avaliar os impactos térmicos e mecânicos sobre a operação normal da planta.…”