Lithium Hydroxide Reaction for Low Temperature Chemical Heat Storage: Hydration and Dehydration Reaction

Haotai Xu,Lisheng Deng,Yu Bai,Jun Li,Hongyu Huang,Noriyuki Kobayashi,Zhaohong He,Tao Zeng

doi:10.3390/en12193741

Haotai Xu, Lisheng Deng + Show 6 more

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https://doi.org/10.3390/en12193741

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Abstract

As a key parameter of a chemical heat storage material, the hydration and dehydration reaction characteristics of lithium hydroxide (LiOH) at pure vapor condition is unclear. In this study, we focused on the hydration reaction and dehydration process of LiOH at the pure vapor condition. The pressure–temperature diagram of LiOH equilibrium was measured. The hydration and dehydration of LiOH at various conditions have been experimentally investigated. The results show that the steam diffusion can be greatly enhanced at vacuum condition. A thin layer of LiOH is uniformly dispersed in the reactor, which can greatly increase the heat transfer between the LiOH material and reactor, leading to a higher hydration reaction rate of LiOH. Furthermore, the steam pressure, reaction temperature, and the particle size of LiOH can greatly influence the hydration reaction. A maximum hydration reaction rate of 80% is obtained under the conditions of 47 °C, steam pressure of 9 kPa, and particle size of 32–40 μm. LiOH exhibits a different reaction property at the condition of pure steam without air and below atmospheric pressure. A store and reaction condition of LiOH with isolation of air is recommended when apply LiOH as a heat storage material at low temperature.

Highlights

In order to increase the total energy utilization efficient, the application of thermal energy storage technologies, including sensible heat storage, latent heat storage, and chemical heat storage, have been extensively studied in the recent decades [1,2,3,4,5,6]
The long-term heat storage can be possible in chemical substance form; (4) the chemical heat storage can store and release heat at an arbitrary temperature depending on the reaction equilibrium temperature and pressure
The chemical heat storage cycle can be divided into the heat storage process and heat release process, which can be repeated with reversible chemical reaction

Summary

Introduction

In order to increase the total energy utilization efficient, the application of thermal energy storage technologies, including sensible heat storage, latent heat storage, and chemical heat storage, have been extensively studied in the recent decades [1,2,3,4,5,6]. Chemical heat storage shows great advantages with following characteristics [3,4,6]: (1) Chemical heat storage can store and release heat with a relatively high energy density by reversible chemical reaction; (2) chemical heat storage can utilize waste heat during various temperature range by different reaction pairs and selected reaction conditions; and (3) thermal energy can be stored in chemical substances form without any heat loss. The long-term heat storage can be possible in chemical substance form; (4) the chemical heat storage can store and release heat at an arbitrary temperature depending on the reaction equilibrium temperature and pressure. The chemical heat storage cycle can be divided into the heat storage process and heat release process, which can be repeated with reversible chemical reaction. The heat storage operation and the heat release process can be summarized as the following Equations [7,8,9,10]

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