Regeneration of Waste Diatomite from Palm Oil Production Process as a Support Material for PCMs in Thermal Energy Storage in Buildings

Abstract

In this study, the use of spent diatomite, an industrial waste in the palm oil production process, was evaluated as a support material for phase change materials (PCMs). Calcination tests of the diatomite were carried out at different temperatures (400, 550 and 700 °C) and times (1 and 2 h). For the PCMs preparation, the organic phase, mixtures of palm oil and commercial stearic acid esters, were impregnated on calcined diatomite under vacuum. Differential scanning calorimetry (DSC) analyses were performed in order to select the PCM with the highest latent heat of fusion and a range of phase change temperature corresponding to the thermal comfort range. DSC, TGA and FT-IR analyses were performed before and after the application of 360 thermal cycles to establish the thermal and chemical reliability of the PCM. It was found that 700 °C and 1 h are the best conditions of the calcination process, and the PCM consisting in 100 % methyl esters of commercial stearic acid presented the highest value of latent heat of fusion (34.67 J/g) and a phase change temperature range of 16.4 to 33.5 °C. After the thermal cycles, the results show that the prepared PCMs has thermal and chemical stability.