Water/Ethanol and 13X Zeolite Pairs for Long-Term Thermal Energy Storage at Ambient Pressure

Abstract

Thermal energy storage is a key technology to increase the global energy share of renewables-by matching energy availability and demand-and to improve the fuel economy of energy systems-by recovery and reutilization of waste heat. In particular, the negligible heat losses of sorption technologies during the storing period make them ideal for applications where long-term storage is required. Current technologies are typically based on the sorption of vapor sorbates on solid sorbents, requiring cumbersome reactors and components operating at below ambient pressure. In this work, we report the experimental characterization of working pairs made of various liquid sorbates (distilled water, ethanol and their mixture) and a 13X zeolite sorbent at ambient pressure. The sorbent hydration by liquid sorbates shows lower heat storage performance than vapor hydration; yet, it provides similar heat storage density to that obtainable by latent heat storage (40-50 kWh/m 3) at comparable costs, robustness and simplicity of the system, while gaining the long-term storage capabilities of sorption-based technologies. As a representative application example of long-term storage, we verify the feasibility of a sorption heat storage system with liquid sorbate, which could be used to improve the cold-start of stand-by generators driven by internal combustion engines. This example shows that liquid hydration may be adopted as a simple and low-cost alternative to more efficient-yet more expensive-techniques for long-term energy storage.

Investigation of the impact of zeolite shaping and salt deposition on the characteristics and performance of composite thermochemical heat storage systems

“…Zeolites are known to have stable storage capacities over numerous hydration/dehydration cycles, with high hydrothermal stability. 71 Zeolite@salt composites are more susceptible to exhibit significant loss of the heat and water storage capacities due to salt deliquescence causing a leakage of salt solution, leading to instability of the storage capacities. 29 In this study, the good reversibility of heat and water uptake/release capacities during two cycles was shown in sections 3.3.1. and 3.3.2.…”

“…The hydrothermal stability and the stability of the storage properties after numerous cycles of hydration and dehydration are crucial parameters for thermochemical heat storage applications. Zeolites are known to have stable storage capacities over numerous hydration/dehydration cycles, with high hydrothermal stability [71]. Zeolite@salt composites are more susceptible to exhibit significant loss of the heat and water storage capacities due to salt deliquescence causing a leakage of salt solution, leading to instability of the storage capacities [29].…”

Review of Technologies and Recent Advances in Low-Temperature Sorption Thermal Storage Systems

“…Mette et al [70] performed an experimental investigation with binderless zeolite 13X and found a maximum sorption temperature of 85 • C, with an inlet hydrated temperature of 50 • C at 15 mbar. Fasano et al [71] studied zeolite adsorbents with different adsorbates, such as distilled water, ethanol, and ethanol-water mixture. The results showed that the ethanol mixture and ethanol dehydrated faster at lower temperatures than water.…”

Minimal set of crystallographic descriptors for sorption properties in hypothetical Metal Organic Frameworks: Role in sequential learning optimization

“…We highlight that sorption-based engineering applications rely upon sorbent material characterization in a wide coverage range. However, when a large number of hypothetical sorbents (here MOFs, but also zeolites in principle [50,51]) have to be evaluated as potential candidates, only low-coverage characterization (i.e. Henry coefficient) is often accessible thus making challenging any optimization of crucial figures of merits of engineering relevance.…”