Phase Change Material Particles and Their Application in Heat Transfer Fluids - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 463

Sample Collection

Diffusion Dryer

DMA

Atomizer CPC

Fig. 11 An aerosol system for production of PCM nanoparticles

Condensation Particle Counter (CPC). Advantages of this method include its ability
to control particle size and chemical composition, and also its high reliability.

4.2.2 Size Control of NPG Nanoparticles

The NPG PCM nanoparticle size can be effectively regulated by changing the air
flow rate (or inlet air pressure) and the solution concentration in our aerosol
system. For example, higher inlet air pressure would generate higher shear force in
the air flow, and then rupture solution droplets to smaller size. The nanoparticle
size distribution can be real-time monitored using the DMA. The as-prepared PCM
nanoparticles are polydisperse in nature, as shown in Fig. 12 . However, mono-
disperse nanoparticles (2-1,000 nm) can be generated by using an electrostatic
band-pass filter from the initial wider distribution. The filtration is accomplished
using a DMA or a nano-DMA developed most recently.

5 Phase-Changeable Nanoemulsion Fluids

A new type of PCM fluids, nanoemulsion fluids, has been recently developed for
thermal energy storage and transfer [ 44 ]. The synthesis and properties of these fluids
are fundamentally different from traditional PCM fluids, such as microcapsule
slurries and nanofluids, as discussed below. One fluid is dispersed into another
immiscible fluid as nanosized structures such as droplets and tubes to create a