No 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.

No abstract

Cyclically utilized electronics provide an interesting challenge for thermal management. Phase Change Materials (PCM) are ideal for cyclic operations due to their high capacity to store heat, however, many phase change materials do not exhibit sufficient conductivity to be effective in larger sizes. Conductivity enhancement can be done in a number of ways including the use of foams or nanomaterials. This experimental study examines the thermal behavior of PCMS with carbon nanofibers conductivity enhancement during solidification. The enhanced PCM is found to exhibit lengthened melt times and shortened cool-down times.

Phase Change Materials (PCMs) are used for thermal management and are ideal for cyclic operations due to their high capacity to store heat. Most PCMs do not exhibit sufficient conductivity to be effective at larger sizes. Enhancing conductivity can be done in a number of ways including carbon foam. It is not widely known how well PCMs penetrate inside the carbon foam structure. Initial research suggests that the carbon foam-PCM matrix acts more as a conductor than a thermal storage device. Through the use microscopy, we will examine how the well the PCM penetrates into the carbon foam. We will also use experimental data comparing carbon foam enhanced modules to pure PCM modules. A volume displacement test will also be used to determine the quantity of PCM that enters into the carbon foam structure. This knowledge will allow better design of enhanced PCM modules and will determine if carbon foam is indeed a viable conduction enhancer for PCM thermal management.