Enhancing Heat Capacity of Colloidal Suspension Using Nanoscale Encapsulated Phase-Change Materials for Heat Transfer

Abstract

This paper describes a new method to enhance the heat-transfer property of a single-phase liquid by adding encapsulated phase-change nanoparticles (nano-PCMs), which absorb thermal energy during solid-liquid phase changes. Silica-encapsulated indium nanoparticles and polymer-encapsulated paraffin (wax) nanoparticles have been made using colloid method, and suspended into poly-alpha-olefin (PAO) and water for potential high- and low-temperature applications, respectively. The shells prevent leakage and agglomeration of molten phase-change materials, and enhance the dielectric properties of indium nanoparticles. The heat-transfer coefficients of PAO containing indium nanoparticles (30% by mass) and water containing paraffin nanoparticles (10% by mass) are 1.6 and 1.75 times higher than those of corresponding single-phase fluids. The structural integrity of encapsulation allows repeated use of such nanoparticles for many cycles in high heat generating devices.

Nano-enhanced phase change materials for improved building performance

“…Therefore, the thermal properties of nano-enhanced PCMs with different sizes, geometries and volume fractions of nanometer-sized materials should be measured in order to determine the best mixture. The thermal properties of nano-enhanced PCMs can be characterized by using a wide range of techniques and some commonly used techniques [7,33,[37][38][39][40][41] are summarized in Table 1.…”

Temperature stabilisation in Fischer–Tropsch reactors using phase change material (PCM)

“…This is especially true for heterogeneous reactions like the FTS, where chemical reactions occur on active catalyst sites [4,[13][14]. Micro-encapsulated PCM, with a phase transition temperature (ptt) lying between a nominal operating temperature and the onset temperature of carbon deposition or catalyst de-activation (whichever occurs first) can act as a rapid-responding, distributed temperature controller [4,[13][14].…”

“…This has huge potential for keeping the propensity of the FBR for parametric sensitivity and vacillation between multiple steady states in check. This is because through its isothermal phase transition (fusion and melting) cycles, the PCM acts as a thermal flywheel mitigating temperature excursions on the one hand while preventing reaction extinction on the other [4,13].…”

“…These two scenarios depict the extremes of multiple stationary states that could be brought about by thermal instabilities. [7,[13][14].…”

“…This requirement for excellent heat rejection has inspired the wide variety of FT reactor designs available on the market today such as: the fluidised bed (circulating and fixed), slurry phase, and fixed bed reactors (FBR), etc. [3,[9][10][11][12][13]. The FTS is broadly classified into two categories namely: the Low Temperature …”