Karakterisasi Garam Lokal Aceh sebagai Kandidat Phase Change Materials (PCM) untuk Thermal Energi Storage

Abstract

Thermal energy storage plays important role in energy system and helps in optimize the overall efficiency. Development of energy storage system for particular purposes requires some information on the raw material which is abundantly available at nearby market. This research focused on the characteristics of NaCl salt which traditionally produced in Aceh as candidate material for thermal energy storage application. Enhancing the properties of this traditional salt was started by preparing three kinds of samples including (i) NaCl without heat treatment, (ii) NaCl pre-heated at 400˚C and (iii) NaCl preheated at 800˚C. Sample characterization was carried out under XRF, XRD, SEM/EDS, TGA/DSC analyses. Density, thermal conductivity and electrolyte conductivity were also measured during this investigation. The performance of phase change material (PCM) samples was evaluated in a 5 litter cooler box. The heat transfer rates and temperature changes within coller box enveloped with water-salt solution as PCM. From the XRF characterization, it was found that Aceh locally produced NaCl was categorized as salt grade-III. TGA/DSC analysis result showed a melting temperature of 800˚C and an enthalpy of 492 kJ/kg. This suggests that the prepared samples are potential to be used as a thermal energy storage. Furthermore, preheating the salt at higher temperatures does not significantly affect on the melting temperature. In term of melting enthalpy and specific heat capacity, increases were observed within sensible heat region upon increasing the temperature of pretreatment. Meanwhile, within the latent heat region, the specific heat capacity was decreased. The XRD analysis result indicated that preheating the salt at higher temperatures resulted in increases in the size of crystal. Similar effect was also observed in parameter of density and electrolyte conductivity. Based on the performance test of water-salt solution PCM in the coller box, it can be learnt that adding 10 wt.% commercial NaCl in water improved the ability in storing and releasing the energy up to 73% compared to 100% water PCM. Furthermore, Aceh traditional NaCl which was preheated to a temperature of 400˚C showed better performance, compared to those preheated at 600˚C.