New, efficient phase-change microcapsule for solar energy storage

It is no news that society’s reliance on non-renewable fossil fuels has led to the ongoing global energy and climate crisis. Emissions from coal, natural gas and petroleum-derived fuels are the main causes of air pollution and, therefore, global warming. In society’s drive to transition to a sustainable, carbon-free energy economy, solar energy holds great promise. Abundant and environmentally friendly solar energy, if harnessed efficiently, can reduce our dependence on conventional energy sources.

In this regard, phase change material (PCM), substances that release/absorb enough energy at phase transition (as latent heat) to provide useful heat/cooling, are a popular candidate such as Solar storage device. Studies have shown that a solar-based PCM cooling system can reduce the ambient temperature by 30 degrees Celsius. Unfortunately, actual PCMs suffer from leakage and corrosion problems. . Furthermore, they show poor heat transfer properties due to heat conductivity. Although this can be solved by using metal PCMs, it makes PCMs more expensive and bulkier.

One way around these problems, as studies have shown, is to encapsulate PCMs in microcapsules with highly conductive fillers, such as nanoparticles. This can protect them from the harmful effects of light, heat, moisture and oxygen as well as improve their heat transfer properties. In addition, many researchers have used low-density, non-metallic, high thermal conductivity nanoparticles for this purpose, in order to avoid the problems of metal nanoparticles.

In a recent breakthrough, researchers from China and the United States have synthesized PMC microcapsules that show unprecedented photothermal conversion and heat transfer using n-Octadecane (ODE) as PCM core and silicon carbide (SiC) nanodoped cross-linked polystyrene (CLPS) as outer shell.

“Phase Change microcapsules Materials are the focus of our research. In a previous study, we found that a single organic shell had defects in thermal conductivity and stability, while a single inorganic shell failed to meet the requirements for compactness and occlusion. government. Therefore, we started to focus on doping organic shells with inorganic nanoparticles to obtain organic-inorganic hybrid shells,” said Professor Jifen Wang from Shanghai Polytechnic University, China, a One of the study’s authors, published online September 29, explains 2022 in Store and save energy.

In their work, the team prepared a series of four microcapsules using a method called “suspension polymerization”. They then characterized the microcapsules using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The results indicate that the microcapsules are spherical and that the nano-SiC particles are embedded in the CLPS shell, supporting the efficient heat transfer and photothermal conversion of the microcapsules.

Next, the team examined the thermal properties of the microcapsules and found that they showed superior photothermal conversion and thermal conductivity compared with the undoped samples. Among the four types of doped microcapsules, the 1.25% nano-SiC doped one exhibited the best performance, with a photothermal conversion efficiency of 54.9%, 146% higher than that of the undoped type. complex.

With such encouraging results, the new PCM microcapsules could provide a solid framework for further studies in energy materials with excellent solar energy storage and conversion efficiency. . The research also opens new doors for the practical application of multifunctional phase-modified microcapsules.

“These microcapsules could have significant potential applications as energy storage materials in solar devices, smart insulation and energy efficient buildings,” said Professor Wang. save energy”.

Provided by Cactus Communications