Microencapsulated Paraffin Phase-Change Material with Calcium Carbonate Shell for Thermal Energy Storage and Solar-Thermal Conversion

Abstract

A series of microencapsulated phase-change materials (MEPCMs) based on paraffin core and calcium carbonate (CaCO 3 ) shell were synthesized, and the effect of emulsifier type and pH value on morphology, structure, and properties of paraffin@CaCO 3 MEPCMs were investigated. The results showed that CaCO 3 shell was formed in vaterite and calcite crystalline phase when emulsifier was sodium dodecyl benzene sulfonate and styrene-maleic anhydride (SMA), respectively. When sodium dodecyl sulfate was used as an emulsifier, both vaterite and calcite CaCO 3 were formed. The forming mechanism of emulsifier type on CaCO 3 crystalline phase was studied. Furthermore, phase-change enthalpy and leakage rate of MEPCMs were related with the type of emulsifier and the pH value of the emulsion. With optimum condition of SMA as emulsifier and pH value of 7, paraffin@CaCO 3 MEPCMs had an encapsulation ratio at 56.6% and leakage rate at 2.88%, illustrating its considerable heat storage capability and leakage-prevention property. The 50 heating−cooling cycles test indicated that the MEPCMs owned excellent thermal reliability. The thermal conductivity of MEPCMs was significantly improved due to the existence of CaCO 3 shell. In addition to excellent thermal storage ability, the paraffin@CaCO 3 MEPCMs also owned good mechanical property and light-to-heat energy conversion efficiency. The characteristics of MEPCMs indicated its potential application in solar energy resource.

Phase Change Material (PCM) Microcapsules for Thermal Energy Storage

“…Compared with organic materials, inorganic shells generally have higher rigidity, higher mechanical strength, and better thermal conductivity [52]. Silica (SiO 2 ) [70][71][72], zinc oxide (ZnO) [73,74], titanium dioxide (TiO 2 ) [75][76][77], and calcium carbonate (CaCO 3 ) [78][79][80] are generally utilized as inorganic shell materials. e advantages of high thermal conductivity, fire resistance, and easy preparation lead silica to be one of the .…”

“…Advances in Polymer Technology most commonly used shell materials. Silica is often employed to microencapsulate organic paraffin waxes [78,81], inorganic hydrated salts [71,[82][83][84], and fatty acids [85,86]. Liang et al used silica as the shell material and noctadecane as the core material to prepare nanocapsules through interfacial hydrolysis and polycondensation of tetraethoxysilane (TEOS) in miniemulsion [87].…”

Expanded Graphite/Paraffin/Silicone Rubber as High Temperature Form-stabilized Phase Change Materials for Thermal Energy Storage and Thermal Interface Materials

“…The other is to microencapsulate PW into core/shell structures. Various types of core and shell materials have been widely explored, including graphene [17,18], polymer shells of PMMA [19], PS [20] and PU [21], and inorganic shells of SiO 2 [4,[22][23][24][25] and CaCO 3 [26], etc. In general, the liquid leakage issue of PW can be effectively prevented by utilizing the compatibility between a polymer and PW, as the polymeric matrix can fix PW by a strong intermolecular force, therefore suppressing PW leaching [27,28].…”

Phase change microcapsules with lead tungstate shell for gamma radiation shielding and thermal energy storage

“…Compared with the polymer shell material, inorganic shell material shows high thermal conductivity, thermal and chemical stability, and mechanical strength. [25][26][27] Wang et al and Jiang et al 25,26 encapsulated the PCM into a CaCO 3 shell and found that these rigid shell microcapsules achieved thermal conductivity enhancement. Many studies have explored the introduction of different inorganic particles to polymer shell microcapsule systems such as silica (SiO 2 ), titania (TiO 2 ), Si 3 N 4 , and so on.…”

“…23,24 Microencapsulated PCM has been successfully prepared using alternative inorganic materials like CaCO 3 , TiO 2 , and graphene. [25][26][27] Wang et al and Jiang et al 25,26 encapsulated the PCM into a CaCO 3 shell and found that these rigid shell microcapsules achieved thermal conductivity enhancement. Ma et al 28 successfully synthesized microencapsulated PCMs (MEPCMs) with paraffin core and inorganic TiO 2 shell through in-situ hydrolysis and polycondensation of tetrabutyl titanate.…”