The role of particle dopant to the thermal conductivities of PCM coconut oil by means of the T-history method

Abstract

We described in this paper the role of chemical dopant to the thermal conductivity of organic phase change material (PCM) of coconut oil (co_oil) based on T-history method. We used the nanoparticle dopant, namely graphite, CuO, and ZnO. Each kind of dopant was added to co_oil in a certain amount of 1 wt% and 2 wt%. For comparison, the data of pure co_oil was also taken and compared to the data from direct measurement. Because of the smaller diameter to height ratio, the lumped capacitance method is applicable here. Hence, the heat transfer between PCM and water during solidification or melting process is one dimensional, so that the one-dimensional transient heat diffusion equation for cylindrical geometry is applicable. Analysis of the data for solidification and melting processes led to the values of solid and liquid thermal conductivities. We note that in general 1 wt% dopants have effectively increased the thermal conductivities of co_oil, which is important for the effective heat transport of the material in response to the heat from the environment. More increase of dopant concentration has resulted in the reduction of thermal conductivities, which might be due to the agglomeration of particle dopant due to van der Waals interaction between particles.