Yutang Fang

Preparation of nanoencapsulated phase change material as latent functionally thermal fluid

Nanoencapsulated phase change material with polystyrene as the shell and n-octadecane as the core was synthesized using the ultrasonic technique and miniemulsion in situ polymerization. The influences of polymerization factors, including initiator, chain transfer agent (CTA), surfactant, n-octadecane/styrene ratio and hydrophilic co-monomer, on the morphology and thermophysical properties of nanocapsules were systematically investigated. The optimized polymerization conditions were 0.5 wt% of initiator (2,2-azobisisobutyronitrile), 0.4 wt% of CTA (n-dodecyl mercaptan), 2% of composite surfactants which were composed of sodium dodecyl sulfate and poly-(ethylene glycol) monooctylphenyl ether by 1 : 1 in weight ratio, 1 wt% of hydrophilic co-monomer butyl acrylate or 3 wt% of methyl methacrylate and 1 : 1 n-octadecane to styrene in weight ratio. Under these conditions, the z-average size of prepared nanocapsules was 124 nm and the phase change enthalpy was 124.4 kJ kg −1 . The heat capacity was as high as 11.61 kJ kg −1 K −1 at the latex concentration of 20.6 wt%. Thermal stability and viscosity testing show that this fluid had excellent resistance to thermal shock (after 100 cycles, no liquid Oct was observed during heating) and low viscosity (only 3.61 mPa s at the latex concentration of 20.6 wt%), which seems to be promising as a latent functionally thermal fluid.

An Overview of Adsorbents in the Rotary Desiccant Dehumidifier for Air Dehumidification

This review discusses the challenges and opportunities for adsorptive dehumidification for rotary desiccant dehumidifiers. As well, it presents an overview of current approaches and emerging technologies in the development of high-performance adsorbents for air dehumidification, including silica materials, activated carbons (ACs), supported haloid-based salts, zeolites, metal organic frameworks (MOFs), etc. The adsorption–desorption characteristics—that is, adsorption isotherms—and adsorption kinetics of different kinds of adsorbents are reviewed and further discussed. Some important issues to further advance the research and development of adsorptive dehumidification for rotary desiccant dehumidifiers are also summarized in this work.

Heat Transfer of Boiling R134a and R142b on a Twisted Tube with Machine Processed Porous Surface

Abstract The objective of this work was to investigate nucleate pool boiling heat transfer performance and mechanism of R134a and R142b on a twisted tube with machine processed porous surface (T-MPPS tube) as well as to determine its potential application to flooded refrigerant evaporators. In the experimental range, the boiling heat transfer coefficients of R134a on a T-MPPS tube were 1.8–2.0 times larger than those of R134a on a plain tube. In addition, the developed experimental correlations verified that the predictions of the heat transfer coefficients of boiling R134a and R142b on a T-MPPS tube at the experimental conditions were considerably accurate.