TES Nanoemulsions: A Review of Thermophysical Properties and Their Impact on System Design

Abstract

Thermal energy storage materials (TES) are considered promising for a large number of applications, including solar energy storage, waste heat recovery, and enhanced building thermal performance. Among these, nanoemulsions have received a huge amount of attention. Despite the many reviews published on nanoemulsions, an insufficient number concentrate on the particularities and requirements of the energy field. Therefore, we aim to provide a review of the measurement, theoretical computation and impact of the physical properties of nanoemulsions, with an integrated perspective on the design of thermal energy storage equipment. Properties such as density, which is integral to the calculation of the volume required for storage; viscosity, which is a decisive factor in pressure loss and for transport equipment power requirements; and thermal conductivity, which determines the heating/cooling rate of the system or the specific heat directly influencing the storage capacity, are thoroughly discussed. A comparative, critical approach to all these interconnected properties in pertinent characteristic groups, in close association with the practical use of TES systems, is included. This work aims to highlight unresolved issues from previous investigations as well as to provide a summary of the numerical simulation and/or application of advanced algorithms for the modeling, optimization, and streamlining of TES systems.

Microfluidic Methods for Generation of Submicron Droplets: A Review

“…The presence of submicron droplets in the material can also modify the viscosity, thermal conductivity, and surface tension. These properties—along with latent heat and specific heat capacity—can be regulated to realize better thermal storage [ 10 ]. However, the submicron scale of the droplets may induce challenges of increased supercooling, which is unexpected in the recycling of the PCM when the phase transition occurs at lower temperature than the melting point, which would cost extra energy input to reduce temperature for reaching the phase transition.…”

“…Another advantage of the submicron droplets relies on their high dispersity and large surface-to-volume ratio reaching up to 10 m 2 /cm 3 [ 2 ]. This allows for submicron droplets that are widely presented in fields such as food [ 7 ], cosmetics [ 8 ], drug delivery [ 9 ], and composite materials [ 10 ]. Recently, in photo harvesting materials, liquid metal (LM) submicron droplets as the thermal conduction elements in a composite material, contribute to solar-heat-electric conversion [ 11 ].…”

Thermal Storage: From Low‐to‐High‐Temperature Systems

“…Based on the PCM, different surfactants are required to reach an optimal long‐term stability. [ 15–17 ]…”

“…Based on the PCM, different surfactants are required to reach an optimal long-term stability. [15][16][17] Supercooling in PCS limits the benefits from high latent heat storage capacity in narrow-temperature intervals, because the PCM crystallization is shifted to lower temperatures compared to the respective PCM melting point. It is related to the PCM droplet size on micrometer scale, as a separation of naturally available crystallization seeds occurs.…”