Preparation and flow characteristic of a novel phase change fluid for latent heat transfer

Zou, Deqiu; Zhou, Feng; Xiao, Rui; Qin, Kun; Zhang, Jianjun; Song, Wei; Tu, Qiu

doi:10.1016/j.solmat.2010.07.028

Cited by 29 publications

(10 citation statements)

References 14 publications

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“…In addition, agglomeration of the microcapsules can cause problems such as increased viscosities. The agglomeration of the microcapsules can be reduced by utilizing a reasonable microcapsule concentration [8] and by using surfactants. [3,6] Flotation can be adverted by using smaller microcapsules [8] and by balancing the density of the microcapsules and the carrier medium.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent structural breakdown of microencapsulated phase change materials suspensions

Cao

Bringas

Schüller

et al. 2018

Journal of Dispersion Science and Technology

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Microencapsulated phase change materials (MPCM) suspensions are multi-phase heat transfer fluids which exploit the latent heat of phase change materials. The effect of MPCM on the rheological properties of suspensions of microcapsules in glycerol were investigated to explore the suitability of the suspensions as a pumpable heat transfer fluid. Three different rheological models were utilized to characterize the time-dependent structural breakdown of the suspensions, and the second-order structural kinetic model was found to give a better fit to the experimental data than the Weltman and Figoni-Shoemaker models. The MPCM form agglomerates, which are disrupted by shear forces. The breakdown of the agglomerated structures was most pronounced at high shear rates where the microcapsules are subjected to stronger disruptive forces. More agglomerates are present at higher concentrations, which causes a stronger breakdown of the agglomerated structures when the concentration is raised. The time-dependent structural breakdown of MPCM suspensions plays an important role for improving the efficiency of heat transfer liquids based on such materials.

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Section: Introductionmentioning

confidence: 99%

Time-dependent structural breakdown of microencapsulated phase change materials suspensions

Cao

Bringas

Schüller

et al. 2018

Journal of Dispersion Science and Technology

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“…Phase inversion can be achieved either by changing the temperature (phase inversion temperature, PIT) [38,39] or by changing the volume fractions of water/oil (emulsion inversion point, EIP) [2,12,[40][41][42]. The most important part of phase inversion is crossing the inversion line which is the solid black line shown in Fig.…”

Section: Low-energy Methodsmentioning

confidence: 99%

“…Adding water to surfactant and oil mixture followed by inversion is indeed a widely used method. As both of the lipophilic and hydrophilic surfactants are used, this method is sometimes modified as in the mixing film synthesis [12,42]. As mentioned before, the inversion can take place in a catastrophic or transitional way.…”

Section: Low-energy Methodsmentioning

confidence: 99%

“…Moreover, in the actual air-conditioning systems, the working fluid is typically exposed to strong mechanical stresses, which may lead to coalescence in emulsions that are otherwise stable under static conditions or under pressure variations of lower magnitude [58]. Zou et al [42,47] suggested two principles to overcome the instability. a) Seek an optimal concentration of PCM.…”

Section: Solutions To Instabilitymentioning

confidence: 99%

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

Shao

Darkwa

Kokogiannakis

2015

Energy and Buildings

101

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Phase change material emulsions (PCMEs) are multifunctional fluids consisting of phase change materials (PCMs) and carrier fluids. PCMEs could be potential candidates as heat transfer media in heating, ventilation and air conditioning (HVAC) systems. This is mainly because PCME could take advantage of its high heat capacity to reduce flow rate and thus saving pumping power whilst delivering the same amount of cooling effect. PCME can also simultaneously act as cold storage to shift peak-load to off-peak time and improve the COP of systems. However, the optimum design of integrated system requires a good understanding of flow behaviour and heat transfer characteristics of PCMEs. In this paper, comprehensive reviews of their thermophysical properties and potential applications as thermal energy storage and as alternative heat transfer fluids in air conditioning systems have been carried out to establish their limitations for future research. systems. This is mainly because PCME could take advantage of its high heat capacity to reduce flow rate and thus saving pumping power whilst delivering the same amount of cooling effect. PCME can also simultaneously act as cold storage to shift peak-load to off-peak time and improve the COP of systems. However, the optimum design of integrated system requires a good understanding of flow behaviour and heat transfer characteristics of PCMEs. In this paper, comprehensive reviews of their thermo-physical properties and potential applications as thermal energy storage and as alternative heat transfer fluids in air conditioning systems have been carried out to establish their limitations for future research.

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“…The reason may be that the crystallization of PCMs in PCSs is retarded by the increasing of inactive seed crystal that has emerged in smaller particle size, furthermore enlarging the supercooling extent. 11−13 Previous literatures 5,4,10,13,14 involved in PCSs can be available where long-chain alkane (tetradecane, hexadecane, and paraffin) as PCMs is the most frequent used. Rather than possessing the conventional advantages of abundant sources, lower cost, chemical inertness, and nontoxicity in long-chain alkane, fatty acids also feature noninflammability, which enable them to be employed at higher temperature.…”

Section: Introductionmentioning

confidence: 99%

Thermophysical Properties of Some Fatty Acids/Surfactants as Phase Change Slurries for Thermal Energy Storage

et al. 2015

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Capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and their eutectics are chosen as phase change materials to constitute the phase change slurries for the first time. Under the emulsification of span20/SDS, phase change slurries with 30 wt % fatty acids are then fabricated by high-speed shearing. Thermophysical properties of phase change slurries are characterized by means of DSC. Results indicate that eutectic phase change slurries exhibit lower freezing/melting peak temperatures than corresponding fatty acids slurries. In the melting, peak temperatures from 22.36°C to 55.61°C and the freezing peak temperatures from 14.61 to 48.97°C, latent heat fusion of eutectic phase change slurries are between 36.32 J/g and 51.82 J/g, 34.35 J/g and 48.58 J/g in the endothermic/exothermic processes. Heat fusion has not demonstrated obvious changes under the heating and melting processes, and these values are approximately equal to those of pure fatty acids multiplied by the mass fraction. Additionally, supercooling of phase change slurries are between 0.55°C and 6.55°C, and this phenomenon might be induced by the crystal structures formed in fatty acids eutectics.

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Preparation and flow characteristic of a novel phase change fluid for latent heat transfer

Cited by 29 publications

References 14 publications

Time-dependent structural breakdown of microencapsulated phase change materials suspensions

Time-dependent structural breakdown of microencapsulated phase change materials suspensions

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

Thermophysical Properties of Some Fatty Acids/Surfactants as Phase Change Slurries for Thermal Energy Storage

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