Impact of Porous Structure on Solar Thermal Energy Storage Materials

Project: Research

Project Details

Description

Solar energy is a prospective renewable energy source and Saudi Arabia is located in the 'Global Sunbelt', which has led it to become one of the largest solar energy producers. However, the solar energy is an intermittent energy source. Therefore, a suitable thermal energy storage system has a high demand for environmental protection and better utilization of the solar energy. Phage change materials (PCMs) have attracted great attention due to its ability to store solar thermal energy in the era of the energy crisis. Designing a perfect PCM is very tedious matter due to its critical requirement for adequate storage criteria. Only 50 PCMs are commercially available after testing a huge number of organic and inorganic PCMs in a real application. Compared to organic PCMs, inorganic PCMs possesses unique properties viz. higher latent heat per unit volume, higher thermal conductivity (around 0.5 W/mK), low volume change, recyclable, non-flammable and low cost, however, two main shortcomings need to be solved i.e., phase separation, and supercooling effects. Supercooling means, the PCM does not crystallize and exist in a liquid form for a portion of time under phase change temperature or below its freezing point. As a result, serious problems such as controlling temperature shift and an increase of the energy consumption can occur during real application. Most of the inorganic salts lost their activity after phase separation. In fact, once the separation happens, the heat storage of hydrated salts performance will drop significantly and cannot be recovering. Recently, scientists claimed that the most effective technology to minimize the supercooling effect and phase separation is to introduce the porous structure confinement effect that comes from the nanoarchitecture. Therefore, it is important to understand the relationship of the supercooling and the porous structure. An ideal PCMs supporter means materials with different porous structures. The relationship of the phase separation, supercooling and nanopore-confinement strategy with porous structure can provide a good experimental platform to overcome the supercooling problems. In fact, research report about this porous support is very limited. Recently, we have developed a noble porous structure fabrication route by the facile hydrothermal method at low temperature. MgCO3 alone and Ba, Ca doped-MgCO3 materials with unique porous structure have been synthesized by hydrothermal method. In addition, MgCO3 is nontoxic, cheap and could be an eco-friendly porous supporter. During the crystallization process beside the pore-confinement effect, which derived from the porous structure, also heterogeneous nucleation might occur. The heterogeneous nucleation can mitigate the phase separation in the porous MgCO3 support matrix, the same behaviour already observed for the CaCO3 porous matrix. In this project, MgCO3 alone or doped MaCO3 porous support will be mix with Na2HPO4.12 H2O PCM to minimize the supercooling effect and phase separation. Na2HPO4.12 H2O inorganic salt will be select as PCM because of their largest heat storage capacity among low temperature PCMs. We will also examine the thermal conductivity improvement by dispersing carbon nanotube over the mix solution.
StatusFinished
Effective start/end date15/04/1815/11/21

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