• Energy Research

Abstract A shape-stabilised n-octadecane/activated carbon nanocomposite was successfully prepared using a one-step impregnation method. Activated carbon (AC) was used as an inorganic framework material, and n-octadecane was used as a phase change material (PCM) for thermal energy storage. The mass loading percentage of n-octadecane in the PCM nanocomposites which was determined using DSC is 42.5 wt.%, due to the excellent adsorption ability of AC. Field Emission Scanning Electron Microscope (FESEM) images and nitrogen adsorption–desorption results for the nanocomposites PCM indicate that n-octadecane was uniformly adsorbed into the pores of AC. The porous networks of the AC prevented leakage of the melted n-octadecane during the phase change processes. The performance of the n-octadecane/AC nanocomposites as a thermal energy storage material for building applications was examined by incorporation of the nanocomposite with gypsum to function as a panel board. The results indicate that the incorporation of the n-octadecane/AC nanocomposites in gypsum board lowered the indoor temperature fluctuation of the buildings, which could reduce energy consumption.

Abstract Thermal energy storage based on organic phase change materials (OPCMs) has attracted much attention to various applications for their excellence properties. However, OPCMs suffers from liquid leakage problem and low thermal conductivity, which limit their application as TES material. Encapsulation of OPCMs using organic or inorganic supporting materials is an effective way to overcome the leakage problem and enhancing their thermal conductivity property. In addition, the capsules could prevent possible interaction between OPCMs with the environment. There are many technologies described the encapsulation of OPCMs which depending on the type of supporting material and chemical properties of the OPCMs used. However, no complete overview of the techniques for encapsulation of OPCMs is available in the open literature. In this paper, we reviewed the techniques used for encapsulation of OPCMs and the method used to characterize the physico-chemical and thermal properties of encapsulated OPCMs. We believed that this review could provide useful information on the various encapsulation methods of OPCMs.

Abstract This work focuses on the preparation of AC (activated carbon) through a physical activation method using peat soil as a precursor, followed by the use of the AC as an inorganic framework for the preparation of SPCM (shape-stabilized phase change material). The SPCM, composed of n-octadecane as the core and AC pores as a framework, was fabricated by a simple impregnation method, with the mass fraction of n-octadecane varying from 10 to 90 wt.%. The AC has a specific surface area of 893 m 2 g −1 and an average pore size of 22 A. The field emission scanning electron microscope images and nitrogen gas adsorption-desorption isotherms shows that the n-octadecane was actually encapsulated into the AC pores. The melting and freezing temperatures of the composite PCM (phase change material) were 30.9 °C and 24.1 °C, respectively, and its corresponding latent heat values were 95.4 Jg −1 and 99.6 Jg −1 , respectively. The composite shows a good thermal reliability, even after 1000 melting/freezing cycles. The present research provided a new SPCM material for thermal energy storage as well as some new insights into the design of composite PCM by tailoring the pore structure of AC derived from peat soil, a natural resource.

AbstractThe effect of the surface area of palm kernel shell activated carbon (PKSAC) on the properties of n-octadecane-encapsulated shape stabilized phase change material (SSPCM) for thermal energy storage (TES) application were studied. Various surface areas of the PKSAC were prepared using different amounts of H3PO4 treatment given to palm kernel shells from 0, 5, 10, 30 and 40% before the activation. The impregnation of n-octadecane into the different surface areas of PKSACs produced SSPCMs with different physico-chemical characteristics. The DSC analysis indicates that the higher the surface area of the PKSAC resulted in the higher freezing temperature due to the higher PCM loading that was encapsulated into the PKSAC pores. The results obtained from XRD, FESEM, Raman spectroscopy, TGA/DTG and leakage study indicate that the PKSAC is a good framework material for the development of n-octadecane-encapsulated SSPCM. It was also found that the surface area and porosity of the frameworks, activated carbon play an important role on the PCM loading percentage and their ability to be used as a thermal energy storage material.

The preparation of activated carbon using palm kernel shells as the precursor (PKSAC) was successfully accomplished after the parametric optimization of the carbonization temperature, carbonization holding time, and the ratio of the activator (H3PO4) to the precursor. Optimization at 500 °C for 2 h of carbonization with 20% H3PO4 resulted in the highest surface area of the activated carbon (C20) of 1169 m2 g−1 and, with an average pore size of 27 Å. Subsequently, the preparation of shape-stabilized phase change material (SSPCM-C20) was done by the encapsulation of n-octadecane into the pores of the PKSAC, C20. The field emission scanning electron microscope images and the nitrogen gas adsorption-desorption isotherms show that n-octadecane was successfully encapsulated into the pores of C20. The resulting SSPCM-C20 nano-composite shows good thermal reliability which is chemically and thermally stable and can stand up to 500 melting and freezing cycles. This research work provided a new strategy for the preparation of SSPCM material for thermal energy storage application generated from oil palm waste.

Advanced energy storage technology based on phase change materials (PCMs) has received considerable attention over the last decade for used in various applications. Buildings are the major industry which needs this advanced technology to improve internal building comfort and the reduction of energy usage. However, the main barrier which affects the application of this technology in building sector is the method to incorporate the PCMs into the building materials and the method used to measure the effectiveness of the PCMs as TES in building. In this paper, a review on the TES systems based on PCMs, their thermo-physical and chemical properties, and potential application as TES for buildings have been carried out. The methodologies for the incorporation of PCMs into the building materials, and their thermal performance are discussed.

This study is focused on the preparation and characterisation of n-nonadecane-vinyl copolymer shell nanocapsules for thermal energy storage medium. The n-nonadecane nanocapsules were prepared by a one-step miniemulsion in situ polymerisation method. n-Nonadecane was used as a core while styrene (St) and methylmethacrylate (MMA) was used as a vinyl copolymer shell. The Fourier transform infrared results confirmed that n-nonadecane nanocapsules were successfully synthesised. Morphological characteristic analysis indicates that these nnonadecane nanocapsules that were prepared using St/MMA (4:1) have a spherical shape and a narrow particle size distribution, with an average diameter of 160±11 nm. The maximum encapsulation ratio for n-nonadecane nanocapsules is 45.8 wt%. The DSC result of pure n-nonadecane and n-nonadecane nanocapsules exhibits two different peaks, which are related to their carbon numbers. The temperature and latent heat of melting and freezing of the n-nonadecane nanocapsules were determined to be 33.1 °C, 76.9 J/g and 30.2 °C, 82.0 J/g, respectively. Moreover, n-nonadecane nanocapsules exhibit good thermal and chemical stability, even after 1000 cycles of a thermal cycling test. Based on all of the results, it can be concluded that the n-nonadecane nanocapsules exhibit better energy storage and have good potential for buildings, textiles or other applications.