“…It can be directed to the comparatively stronger colloidal interaction between the CNTs- g- FA and FA. The similar observation was reported for acid modified CNTs/erythritol suspension 21 and CNTs- g -polyalcohol/paraffin suspensions 22 . Figure 3 Photograph image of PA/CNTs- g -PA (5 wt%) and PA/CNT (5 wt%) suspensions after 30 min-standby at 70 °C.…”
Section: Resultssupporting
confidence: 88%
“…As seen from these data, especially the LHC values of the composites including CNTs- g -FA (grafting ratio: 1:3) were 6.5–8.9% higher than that of the composites including CNTs due to the LHC contribution of the CNTs-g-FA additive. On the other hand, when compared the LHC of the FA/CNTs- g -FA composite PCMs with those of different kinds of organic PCMs doped with carbon based fillers 14 – 20 , 22 , 26 , 29 , 36 , it was observed that the FA/CNTs-g-FA composite PCMs prepared in this work had relatively higher LHC than most of them. This boosted in the LHC value of the FA/CNTs-FA composite PCMs was due to the fact that the CNTs- g -FA used as doping agents had LHC of in the range of 25–93 J g −1 .…”
Section: Resultsmentioning
confidence: 73%
“…Reported literature based procedure 22 , 23 , was used to acid functionalize CNTs. Required amount of CNTs (5 g) were added to 350 mL of HNO 3 (60% v/v) solution in a round bottom flask and then stirred at room temperature for 3 h. The reaction mixture was refluxed at 120 °C for 12 h, and then cool to room temperature.…”
Section: Methodsmentioning
confidence: 99%
“…They observed that this treatment improved the dispersion of CNTs in the melted PCM and TC value of the PCM was significantly boosted by adding 1.0 wt% CNTs. Li et al 22 grafted CNTs with octanol, tetradecyl alchohol and stearyl alcohol and then added to paraffin. The results demonstrated that the dispersion ability of grafted CNTs was better than CNTs and the TC of the grafted CNTs/paraffin composite PCMs was relatively higher than that of CNTs/paraffin.…”
In recent year, fatty acids (FAs) are heavily studied for heat storage applications and they have shown promising advantages over other organic phase change materials (PCMs). Among the FAs; capric, palmitic and stearic acids are the most studied PCMs. Several researchers have investigated these FAs and tried to improve their thermal properties, mainly by adding different high conducting fillers, such as graphite, metal foams, CNTs, graphene etc. In most cases, these fillers improved the thermal conductivity and heat transfer property but reduce the heat storage capacity considerably. These composites also lose the mixing uniformity during the charging and discharging process. To overcome these issues, selected FAs were grafted on the functionalized CNT surfaces and used as conductive fillers to prepare FA based composite PCMs. This process significantly contributed to prevent the drastic reduction of the overall heat storage capacity and also showed better dispersion in both solid and liquid state. Thermal cycling test showed the variations in the thermal energy storage values of all composite PCMs, however, within the tolerable grade and they had appreciable phase change stability and good chemical stability even after 2,000 cycles.
“…It can be directed to the comparatively stronger colloidal interaction between the CNTs- g- FA and FA. The similar observation was reported for acid modified CNTs/erythritol suspension 21 and CNTs- g -polyalcohol/paraffin suspensions 22 . Figure 3 Photograph image of PA/CNTs- g -PA (5 wt%) and PA/CNT (5 wt%) suspensions after 30 min-standby at 70 °C.…”
Section: Resultssupporting
confidence: 88%
“…As seen from these data, especially the LHC values of the composites including CNTs- g -FA (grafting ratio: 1:3) were 6.5–8.9% higher than that of the composites including CNTs due to the LHC contribution of the CNTs-g-FA additive. On the other hand, when compared the LHC of the FA/CNTs- g -FA composite PCMs with those of different kinds of organic PCMs doped with carbon based fillers 14 – 20 , 22 , 26 , 29 , 36 , it was observed that the FA/CNTs-g-FA composite PCMs prepared in this work had relatively higher LHC than most of them. This boosted in the LHC value of the FA/CNTs-FA composite PCMs was due to the fact that the CNTs- g -FA used as doping agents had LHC of in the range of 25–93 J g −1 .…”
Section: Resultsmentioning
confidence: 73%
“…Reported literature based procedure 22 , 23 , was used to acid functionalize CNTs. Required amount of CNTs (5 g) were added to 350 mL of HNO 3 (60% v/v) solution in a round bottom flask and then stirred at room temperature for 3 h. The reaction mixture was refluxed at 120 °C for 12 h, and then cool to room temperature.…”
Section: Methodsmentioning
confidence: 99%
“…They observed that this treatment improved the dispersion of CNTs in the melted PCM and TC value of the PCM was significantly boosted by adding 1.0 wt% CNTs. Li et al 22 grafted CNTs with octanol, tetradecyl alchohol and stearyl alcohol and then added to paraffin. The results demonstrated that the dispersion ability of grafted CNTs was better than CNTs and the TC of the grafted CNTs/paraffin composite PCMs was relatively higher than that of CNTs/paraffin.…”
In recent year, fatty acids (FAs) are heavily studied for heat storage applications and they have shown promising advantages over other organic phase change materials (PCMs). Among the FAs; capric, palmitic and stearic acids are the most studied PCMs. Several researchers have investigated these FAs and tried to improve their thermal properties, mainly by adding different high conducting fillers, such as graphite, metal foams, CNTs, graphene etc. In most cases, these fillers improved the thermal conductivity and heat transfer property but reduce the heat storage capacity considerably. These composites also lose the mixing uniformity during the charging and discharging process. To overcome these issues, selected FAs were grafted on the functionalized CNT surfaces and used as conductive fillers to prepare FA based composite PCMs. This process significantly contributed to prevent the drastic reduction of the overall heat storage capacity and also showed better dispersion in both solid and liquid state. Thermal cycling test showed the variations in the thermal energy storage values of all composite PCMs, however, within the tolerable grade and they had appreciable phase change stability and good chemical stability even after 2,000 cycles.
“…Among various emerging nanomaterials, carbon nanotubes have attracted much attention to fabricate composite PCMs with improved thermal properties [15][16][17], because of their unique structure and properties including the huge surface area, excellent electrical and optical properties, and very high thermal conductivity [18][19][20]. The PCM/carbon-nanotube composites were demonstrated to have a highly thermal conductivity [21], by which the heat storage and release time of the composites could be shortened.…”
Thermal energy storage technologies based on phase‐change materials (PCMs) have received tremendous attention in recent years. These materials are capable of reversibly storing large amounts of thermal energy during the isothermal phase transition and offer enormous potential in the development of state‐of‐the‐art renewable energy infrastructure. Thermal conductivity plays a vital role in regulating the thermal charging and discharging rate of PCMs and improving the heat‐utilization efficiency. The strategies for tuning the thermal conductivity of PCMs and their potential energy applications, such as thermal energy harvesting and storage, thermal management of batteries, thermal diodes, and other forms of energy utilization, are summarized systematically. Furthermore, a research perspective is given to highlight emerging research directions of engineering advanced functional PCMs for energy applications.
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