Review of phase change emulsions (PCMEs) and their applications in HVAC systems

Shao, Jingjing; Darkwa, Jo; Kokogiannakis, Georgios

doi:10.1016/j.enbuild.2015.03.003

Cited by 103 publications

(30 citation statements)

References 54 publications

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“…Nevertheless, most of the considered works do not report information on the quality of the emulsion nor on the synthesis yield, related to the ratio of encapsulated paraffin with respect to the initial amount, and therefore it is difficult to make a direct comparison. It should be pointed out that the study of PCM emulsion stability is important not only to maximize the final encapsulation yield but also for the development of high performing heat transfer fluids [44,45,46], which often contain emulsified PCM. In the present study, considerably more effective emulsification of docosane was obtained with CTAB, probably due to its higher hydrophobic character denoted by its lower hydrophile-lipophile balance (HLB) number [26,47,48,49].…”

Section: Resultsmentioning

confidence: 99%

Docosane-Organosilica Microcapsules for Structural Composites with Thermal Energy Storage/Release Capability

et al. 2019

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Organic phase change materials (PCMs) represent an effective solution to manage intermittent energy sources as the solar thermal energy. This work aims at encapsulating docosane in organosilica shells and at dispersing the produced capsules in epoxy/carbon laminates to manufacture multifunctional structural composites for thermal energy storage (TES). Microcapsules of different sizes were prepared by hydrolysis-condensation of methyltriethoxysilane (MTES) in an oil-in-water emulsion. X-ray diffraction (XRD) highlighted the difference in the crystalline structure of pristine and microencapsulated docosane, and 13C solid-state nuclear magnetic resonance (NMR) evidenced the influence of microcapsules size on the shifts of the representative docosane signals, as a consequence of confinement effects, i.e., reduced chain mobility and interaction with the inner shell walls. A phase change enthalpy up to 143 J/g was determined via differential scanning calorimetry (DSC) on microcapsules, and tests at low scanning speed emphasized the differences in the crystallization behavior and allowed the calculation of the phase change activation energy of docosane, which increased upon encapsulation. Then, the possibility of embedding the microcapsules in an epoxy resin and in an epoxy/carbon laminate to produce a structural TES composite was investigated. The presence of microcapsules agglomerates and the poor capsule-epoxy adhesion, both evidenced by scanning electron microscopy (SEM), led to a decrease in the mechanical properties, as confirmed by three-point bending tests. Dynamic mechanical analysis (DMA) highlighted that the storage modulus decreased by 15% after docosane melting and that the glass transition temperature of the epoxy resin was not influenced by the PCM. The heat storage/release properties of the obtained laminates were proved through DSC and thermal camera imaging tests.

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Section: Resultsmentioning

confidence: 99%

Docosane-Organosilica Microcapsules for Structural Composites with Thermal Energy Storage/Release Capability

et al. 2019

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“…Indeed, this slurries have been identified as a thermal storage media and a heat transfer fluid, having potential applications in HVAC, refrigeration and heat exchangers [357][358][359][360][361][362]. When compared to conventional heat transfer fluids, PCM-based slurries have higher specific heat and TES capacity [363], with a small temperature difference between storing and releasing heat.…”

Section: How Can Hvac Fluids and Transport Fluid Movers Improve Buildmentioning

confidence: 99%

“…Similarly to nanofluids, and due to phase change, the heat transfer enhancement decreases volume and mass flow rates, although the increment on the pressure drop. As discussed in the section above, TES with solid-liquid phase change has been a major topic in energy-saving research [255,360,364]. In this field, some problems as the low thermal conductivity (especially in the liquid state) and the solidification and subcooling times were surpassed gathering nanotechnology techniques; by dispersing the multi wall carbon nanotubes, in pure water PCM, resulting in 6 to 9% of energy-saving potential in water chiller system [365].…”

Section: How Can Hvac Fluids and Transport Fluid Movers Improve Buildmentioning

confidence: 99%

A review on current advances in the energy and environmental performance of buildings towards a more sustainable built environment

Soares

Bastos

Pereira

et al. 2017

Renewable and Sustainable Energy Reviews

198

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Nowadays, debates addressing climate change, fossil fuels depletion and energy security highlight the need for a more sustainable built environment in order to reduce energy consumption and emission trends in the buildings sector. Meeting these targets is a challenge that calls for innovative research to improve the use of renewable energy sources, new technologies, and holistic tools and methodologies. Such research should integrate the dynamics and main drivers of energy supply and demand in buildings to support new policies, plans and actions towards lowering the built environment burdens. This paper brings together ten research topics concerning the energy and environmental performance of buildings, which can support a shift towards a more sustainable built environment. Background information and state of the art literature on the covered research topics is briefly summarized, gaps are identified and guidelines for future research are provided. The selected topics cover different stages along the lifetime of buildings (from design and operation, to retrofitting and endof-life), different scale approaches (from building elements/components, to the building, district and urban scales), and different methods to assess the energy and environmental performance of buildings (life-cycle assessment, generative design methods and retrofitting tools). Other topics are discussed such as: nearly zero-energy buildings, the control of domestic energy resources in smart grid scenarios, the need to include end-users' behaviors in the dynamics of energy demand, the advantages of improving thermal storage by using phase change materials, the importance of reducing heating and cooling energy demand (maintaining indoor thermal comfort), and the optimization of heating and cooling fluids, and their system control.

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“…Glycerol based on non-ionic surfactant with the hydrophilic end do not have any negative or positive charge, do not ionise in aqueous solution and therefore do not have a corrosion effect, because of no counter ion and natural neutral. Also, glycerol can apply to different types of crude oil because it is less sensitive to electrolytes and change in pH, which makes it suitable for use with many sorts of crude oil, including high salinity and acidic crude oil [25,26]. Also, glycerol can be used in demulsification water in oil emulsion in small dosage, which make it very economical in comparison to ionic surfactant, as well as contributing low toxicity to the environment [27].…”

Section: Introductionmentioning

confidence: 99%

Separation Emulsion via Non-Ionic Surfactant: An Optimization

2019

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Achieving emulsion stability in the petroleum industry is a major challenge due to several problems encountered in the oil refining process, such as corrosion in equipment, high-pressure drops in pipelines, and catalyst poisoning in upstream facilities. Thus, several methods are applied for emulsion treatment and chemical treatment using surface-active agents, a fundamental method in the petroleum industry. The present work investigated the performance of a non-ionic surfactant in separating water in a crude oil emulsion via the bottle test technique. Then, a Fractional Factorial Design (2 K−1 ) was used to characterise the effect of significant variables. In particular, a Pareto chart was employed and factors such as demulsifier dosage, toluene concentration, pressure, sitting time, and temperature were investigated. Accordingly, the parameters applied were further analysed using a Central Composite Design (CCD) based on the Response Surface Method (RSM). The experimental results based on analysis of Variance (ANOVA) show that demulsifier dosage, temperature, and sedimentation times were the main variables affecting the dehydration process, with the highest F-values being 564.74, 94.53 and 78.65 respectively. The increase in the surfactant dosage before critical concentration, temperature and sitting time leads to boosting dehydration efficiency. In addition, a mathematical model was established for the variables, with a coefficient of determination value of 0.9688. Finally, numerical optimisation was performed on the variables and the results show that the optimal values are 1000 ppm, 15.5 mL, −400 mmHg, 120 min, and 90 • C, for demulsifier dosage, toluene concentration, pressure, sitting time, and temperature, respectively.

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Review of phase change emulsions (PCMEs) and their applications in HVAC systems

Cited by 103 publications

References 54 publications

Docosane-Organosilica Microcapsules for Structural Composites with Thermal Energy Storage/Release Capability

Docosane-Organosilica Microcapsules for Structural Composites with Thermal Energy Storage/Release Capability

A review on current advances in the energy and environmental performance of buildings towards a more sustainable built environment

Separation Emulsion via Non-Ionic Surfactant: An Optimization

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