Development of Methods to Fully Saturate Carbon Foam With Paraffin Wax Phase Change Material for Energy Storage

Abstract

In this work, the effect of infiltration method on the saturation rate of paraffin phase change material within graphite foams is experimentally investigated. Graphite foams infiltrated with paraffin have been found to be effective for solar energy storage, but it has been found that it is difficult to completely saturate the foam with paraffin. The effectiveness of the fill will have a significant effect on the performance of the system, but the data on fill ratio are difficult to separate from confounding effects such as type of graphite or phase change material (PCM) used. This will be the first detailed quantitative study that directly isolates the effect of infiltration method on fill ratio of PCM in graphite foams. In this work, the two most commonly reported methods of infiltration are studied under controlled conditions. In fact, the effect of the infiltration method on the paraffin saturation rate is found to be highly significant. It was found that the more commonly used simple submersion technique is ineffective at filling the voids within the graphite foam. Repeated tests showed that at least 25% of the reported open space within the foam was left unfilled. In contrast, it was found that the use of a vacuum oven lead to a complete fill of the foam. These high saturation rates were achieved with significantly shorter dwell times than in previously reported studies and can be of significant use to others working in this area.

Graphite Foam Infused with Pentaglycerine for Solid-State Thermal Energy Storage

“…However, due to no mechanism for displacing trapped air, this infiltration technique can result in infusions as low as 45% [18]. Some have used vacuum infiltration, in which the foam is evacuated before or during infusion.…”

“…The paraffin-infused samples provided a control, since this type of TES has been studied extensively [8,17,18]. The intent was to evaluate the TES performance of PG-infused samples relative to paraffin samples by subjecting them to the same conditions.…”

An Overview of the Use of Phase Change Materials for the Thermal Management of Transient Portable Electronics: Benefits and Challenges

“…A study by Warzoha et al [19] showed that the commonly used method of submerging the foam or expanded graphite in melted PCM and letting it wick into the solid is ineffective. Repeated tests showed that at least 25% of the reported open space within the foam was left unfilled using this method.…”

“…Repeated tests showed that at least 25% of the reported open space within the foam was left unfilled using this method. It was shown that for effective use of these materials the foam must be fully evacuated and then filled under vacuum conditions [19].…”

Development of graphite foam infiltrated with MgCl2 for a latent heat based thermal energy storage (LHTES) system

“…Recent development of graphite foams with extremely high bulk thermal conductivities [21] has led to several investigations on using them for improving the thermal performance of low thermal conductivity materials [22][23][24][25][26][27][28]. Zhong et al [24] showed that the thermal diffusivity of a paraffin/graphite foam composite was 570 times higher than that of pure paraffin wax.…”