Thermochemical heat storage materials offer high-energy storage densities and clean means of long-term solar energy storage. The aim of the study is to assess the potential heat storage efficiency of salt hydrates, based on sufficient hydration/dehydration performance, water sorption and cyclicability. MgSO4•7H2O, ZnSO4•7H2O and FeSO4•7H2O were evaluate based on preselected criteria. The main highlights of the dehydration result show that higher enthalpy was obtained for MgSO4 and ZnSO4, shows 2256 J g-1 and 1731 J g-1 enthalpy, respectively. During hydration process, six water molecules were absorbing by MgSO4 and ZnSO4 after pre-dehydrated temperature 150 °C and 120 °C, respectively. The cycle stability of MgSO4 and ZnSO4 showed better performance which give rise 1210 g-1 and 1155 J g-1 enthalpy, respectively. It was expected that FeSO4 would show higher cyclicability due to their higher enthalpy (1400 J g-1) in the first round; however, overhydration does not permit it to released larger energy. The impact of relative humidity on water sorption performance and rate of hydration were reported which showed that MgSO4 and ZnSO4 can uptake maximum water under 85 and 75 % relative humidity. Ongoing studies and the booming progress of ZnSO4•7H2O illustrate that likewise MgSO4•7H2O, it is also the potential candidate and can be use in thermochemical heat storage devices. To bring zinc sulfate heptahydrate into market, more detail studies in fields of evaluation of advanced materials and development of efficient and compact prototypes are still required.
ZnSO4·7H2O is modified by impregnation method with zeolite matrices (13X-zeolite and LTA-zeolite) to improve its hydration performance. Water sorption ability of composites was carried out in a constant temperature & humidity environment. Composite of ZnSO4/13X-zeolite showed highest water sorption (0.26 g/g) at 75% relative humidity under 45 °C air temperature, which is double than pure ZnSO4·7H2O. This is due to larger surface area (491 m2 g-1) and pore volume (0.31 cm3). Based on the results, the hydration behavior of MZ9 reveals an ideal thermochemical heat storage candidate for thermal storage devices.
Inhaltsverzeichnis (Table of Contents)
- Abstract
- 1. Introduction
- 2. Material and methods
- 2.1. Materials
- 2.1.1 Composites preparation
- 2.2. Methods
- 2.2.1 Dehydration studies
- 2.2.2 Hydration studies
- 2.2.3 X-ray diffraction
- 2.2.4 Surface morphological and pore size
- 2.1. Materials
- 3. Result and discussion
- 3.1 Dehydration analysis of salts
- 3.2 Dehydration of MgSO4-ZnSO4 composite
- 3.3 Hydration of TCMs under four different temperature zone
- 3.4 Hydration heat of materials at various temperatures
- 3.5 Hydration performance of salt hydrates at relative humidity and temperature
- 3.6. Water Sorption performance of composites
- 3.7 Effect of humidity and temperature on absorption mass and rate
- 3.8 Structural properties of composite materials
- 3.8.1 Brunauer–Emmett–Teller (BET) characterization
- 3.8.2 X-ray diffraction (XRD)
- 3.9 SEM and EDX analysis of 13X pure and composites pellets
- 3.10 Effect of humidity and temperature on absorption performance of salt-salt composites
- 4. Conclusion
- 5. Acknowledgement
- 6. References
Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)
This study aims to evaluate the potential heat storage efficiency of salt hydrates for long-term solar energy storage. The focus is on the hydration/dehydration performance, water sorption, and cyclicability of MgSO4•7H2O, ZnSO4•7H2O, and FeSO4•7H2O.
- Thermochemical heat storage using salt hydrates
- Hydration/dehydration performance of salt hydrates
- Water sorption and cyclicability of salt hydrates
- Development of composite materials for improved performance
- Influence of relative humidity and temperature on water sorption
Zusammenfassung der Kapitel (Chapter Summaries)
The introduction outlines the significance of thermochemical heat storage in addressing intermittency in renewable energy sources like solar energy. It discusses the advantages of thermochemical heat storage (TCES) over other thermal energy storage methods like sensible heat storage (SHS) and latent heat storage (LHS). The chapter explores the existing challenges of pure salt hydrates, like low water sorption and insufficient heat of hydration, and introduces the use of zeolite composites and salt-salt composites to address these issues.
The 'Material and methods' chapter details the materials used in the study and the techniques employed for composite preparation, dehydration analysis, hydration analysis, X-ray diffraction, and surface morphology and pore size determination. The chapter provides a detailed description of the experimental procedures.
The 'Result and discussion' chapter presents the findings of the study. This section analyzes the dehydration behavior of MgSO4•7H2O, ZnSO4•7H2O, and FeSO4•7H2O, highlighting their enthalpy values and energy densities. It discusses the dehydration of the MgSO4-ZnSO4 composite (MZ9) and its improved performance compared to pure salt hydrates. The chapter explores the hydration behavior of the TCMs at various temperatures and the impact of dehydration temperature on water sorption. It then delves into the hydration heat of materials at different temperatures and the influence of relative humidity and temperature on water sorption.
The chapter also investigates the structural properties of composite materials using BET characterization and XRD analysis. It analyzes the surface morphology of zeolites and composites using SEM and EDX, and examines the impact of humidity and temperature on the absorption performance of salt-salt composites. The chapter provides a comprehensive analysis of the results, comparing the performance of different materials and highlighting the key factors influencing their heat storage properties.
Schlüsselwörter (Keywords)
This research focuses on thermochemical energy storage using salt hydrates and composite materials. Key terms include salt hydrate, composites, zeolite, reusability, water sorption, and thermochemical energy storage. The study investigates the potential of MgSO4•7H2O, ZnSO4•7H2O, and FeSO4•7H2O as thermochemical heat storage materials, focusing on their dehydration, hydration, and water sorption characteristics. It also examines the impact of composite materials, such as zeolite-ZnSO4 and MgSO4-ZnSO4, on improving the overall performance of these materials.
- Quote paper
- Ata Ur Rehman (Author), 2020, Thermochemical Heat Storage Materials and their Solar Space Heating Application, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/584060
