Organic Salt Hydrate as a Novel Paradigm for Thermal Energy Storage

Abstract

The use of inorganic salt hydrates for thermochemical energy storage (TCS) applications is widely investigated. One of the drawbacks that researchers face when studying this class of materials is their tendency to undergo deliquescence phenomena. We here proposed and investigated, for the first time, the possibility of using organic salt hydrates as a paradigm for novel TCS materials with low water solubility, that is, more resistance to deliquescence, a tendency to coordinate a high number of water molecules and stability under operating conditions. The organic model compound chosen in this study was calcium; 7-[[2-(2-amino-1,3-thiazol-4-yl)-2-methoxyiminoacetyl]amino]-3-[(2-methyl-5,6-dioxo-1H-1,2,4-triazin-3-yl)sulfanylmethyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, known as calcium ceftriaxone, hereafter named CaHS (calcium hydrated salt), a water-insoluble organic salt, which can combine up to seven water molecules. The CaHS was prepared by precipitation from the water-soluble disodium triaxone. The thermal behavior of CaHS, in terms of stability and dehydration–hydration cyclability, was assessed. The material can operate in the temperature range of 30–150 °C, suitable for TCS. No deliquescence phenomena occurred upon exposure to a relative humidity (RH) between 10 and 100%. Its heat storage capacity, so far unknown, was measured to be ~595.2 kJ/kg (or ~278.6 kWh/m3). The observed heat storage capacity, thermal stability, and good reversibility after dehydration–hydration cycles highlight the potential of this class of materials, thus opening new research paths for the development and investigation of innovative organic salt hydrates.

Softness of hydrated salt crystals under deliquescence

“…In fact, their discovery on the sediments of Mars provided vital information on the hydrogeologic history of other planets. In addition, they are an important class of natural materials that are currently investigated both as thermochemical materials and phase change materials and for energy storage purposes because of their large potential storage capacity (≈1-3 GJ m −3 ) and the easily accessible temperature range that they cover 28,29 . Our results provide insights into the deliquescence, i.e., dissolution at low undersaturation, of hydrated salts compared to anhydrous crystals, which can help for optimizing their performance with improved control over their geometry and size.…”

Analysis of Nucleation Time of Gas Hydrates in Presence of Paraffin During Mechanized Oil Production

“…Gas hydrates, also known as clathrates, are crystalline structures where water molecules form a lattice that encases gas molecules under specific temperature and pressure conditions. The thermodynamic prerequisites for gas hydrate formation vary according to gas type, temperature, pressure, gas saturation, and the salinity of water (1) as well as the compositional makeup of other phases present. Methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), carbon dioxide (CO2), hydrogen sulfide (H2S), nitrogen (N2), and other gases in hydrocarbon production can form hydrates under suitable conditions (2).…”

Fast Formation of Hydrate Induced by Micro-Nano Bubbles: A Review of Current Status

“…It has been proved that the formation and dissociation process of a hydrate is simple; there is almost no mass loss, no environmental protection problem, and the gas storage capacity is large [1,2]. Therefore, hydrate-based technologies have shown great application potential in cold storage [3][4][5][6], gas separation [7,8], storage and transport of gases [9,10], and seawater desalination [11,12], etc. However, the characteristics of poor gas-liquid interface, the randomness of nucleation, the low rate of nucleation, and crystal growth are the key problems that restrict the fast formation of hydrate and its technology application to energy storage.…”