Research on the enhancement and regulation mechanisms of dispersion stability of latent heat functional fluids

doi:10.11949/0438-1157.20250453

Abstract

Abstract:

The dispersion stability of phase change microcapsules in liquid media is a key factor affecting the performance of latent heat functional fluids. The stability of latent heat functional fluids can be enhanced by adding dispersants, but the influence mechanisms and regulatory patterns of dispersants’ intrinsic properties and service environments on this stability remain unclear. Therefore, this paper constructs a coarse-grained molecular dynamics model of latent heat functional fluids to study the effects of nonionic, anionic, and cationic dispersants’ microstructure, composition, and temperature on the stability of latent heat functional fluids. The results show that adding dispersants can improve the aggregation of capsules in functional fluids, but there are significant differences in the stability effects of different types of dispersants and temperatures. The order of dispersant’s effectiveness in promoting the dispersion stability of latent heat functional fluids is as follows: nonionic polyvinyl alcohol (PVA), anionic sodium dodecyl sulfate (SDS), and cationic cetyltrimethylammonium bromide (CTAB).

Key words: phase-change capsules, latent heat functional fluids, dispersants, coarse-graining, molecular dynamics simulation

摘要：

相变微胶囊在液体介质中的分散稳定性是潜热型功能流体服役性能的关键影响因素。通过添加分散剂可强化潜热型功能流体的稳定性，但分散剂本征特性和服役环境等因素对其稳定性的影响规律和调控机理尚不清晰。因此，构建了潜热型功能流体的粗粒化分子动力学模型，研究了非离子型、阴离子型和阳离子型分散剂的微观结构、组分及温度对潜热型功能流体稳定性的影响规律。结果表明，添加分散剂可改善功能流体中胶囊的团聚现象，但分散剂类型和温度对稳定性的影响存在显著差异；分散剂对潜热型功能流体分散稳定的促进作用由大到小依次为：非离子型聚乙烯醇（PVA）、阴离子型十二烷基硫酸钠（SDS）、阳离子型十六烷基三甲基溴化铵（CTAB）。

关键词: 相变胶囊, 潜热型功能流体, 分散剂, 粗粒化, 分子动力学模拟

CLC Number:

TQ 047.4

Ke REN, Xinjian LIU, Zhonghao RAO. Research on the enhancement and regulation mechanisms of dispersion stability of latent heat functional fluids[J]. CIESC Journal, 2025, 76(11): 5584-5593.

任珂, 刘新健, 饶中浩. 潜热型功能流体分散稳定性强化及调控机理研究[J]. 化工学报, 2025, 76(11): 5584-5593.

Figures/Tables 15

Fig.1 Coarse-grained model and the initial configuration of the simulation system

Table 1 Latent heat functional fluid model parameters

体系	尺寸/(nm×nm×nm)	珠子数量
体系	尺寸/(nm×nm×nm)	H₂O	C₁₈	MF	SDS	Na⁺	CTAB	Br^-	PVA
M	30×30×60	12000	1200	20000	0	0	0	0
MS1	30×30×60	12000	1200	20000	300	300	0	0
MS2	30×30×60	12000	1200	20000	600	600	0	0
MS3	30×30×60	12000	1200	20000	900	900	0	0
MC1	30×30×60	12000	1200	20000	0	0	300	300
MC2	30×30×60	12000	1200	20000	0	0	600	600
MC3	30×30×60	12000	1200	20000	0	0	900	900
MP1	30×30×60	12000	1200	20000	0	0	0	0	300
MP2	30×30×60	12000	1200	20000	0	0	0	0	600
MP3	30×30×60	12000	1200	20000	0	0	0	0	900

Fig.2 Density of suspension system with different dispersants

Fig.3 Different suspension system configurations at different temperatures

Fig.4 The change of centroid distance of microcapsules with time in suspension system at different temperatures

Fig.5 Average centroid distance of microcapsules in suspension system at different temperatures

Fig.6 Mean azimuth shift curve of microcapsules in suspension system at different temperatures

Table 2 Diffusion coefficients of dispersants and microcapsules in different suspension systems

体系	D_epcm/(10^-6cm²/s)
体系	300 K	350 K
M	0.159	0.367
MS1	0.692	0.949
MS2	0.331	0.828
MS3	0.170	0.605
MC1	0.867	0.929
MC2	0.348	0.740
MC3	0.335	0.569
MP1	0.403	0.457
MP2	0.185	0.450
MP3	0.166	0.403

Fig.7 The concentration distribution curve of suspension system at different temperature

Fig.8 Density distribution of microcapsules and dispersant molecules on the X-Z plane

Fig.9 Three-dimensional density contour of dispersant molecule

Fig.10 van der Waals energy of suspension system with different temperatures

Fig.11 Average van der Waal energy of suspension system with different temperatures

Fig.12 Electrostatic potential energy of suspension system with different temperatures

Fig.13 Average electrostatic potential energy of suspension system with different temperatures

References 36

[1]	Xu Q, Zhu L D, Pei Y Q, et al. Heat transfer enhancement performance of microencapsulated phase change materials latent functional thermal fluid in solid/liquid phase transition regions[J]. International Journal of Heat and Mass Transfer, 2023, 214: 124461.
[2]	鲁进利, 郝英立. 细小尺度下潜热型功能热流体压降与传热特性[J]. 化工学报, 2010, 61(6): 1385-1392.
	Lu J L, Hao Y L. Pressure drop and heat transfer characteristics of latent functional thermal fluid in mini-scale[J]. CIESC Journal, 2010, 61(6): 1385-1392.
[3]	于云雁, 赵树兴, 甄子亚, 等. 潜热型功能流体太阳能供暖集热系统集热效果实验研究[J]. 太阳能学报, 2021, 42(10): 135-139.
	Yu Y Y, Zhao S X, Zhen Z Y, et al. Experimental research on the efficiency of solar collection system with latent functional thermal fluid for heating[J]. Acta Energiae Solaris Sinica, 2021, 42(10): 135-139.
[4]	石姗姗, 钱钊, 姜涛, 等. 高分子相变材料的导热改性研究综述[J]. 塑料工业, 2022, 50(2): 1-5.
	Shi S S, Qian Z, Jiang T, et al. Review on thermal conductivity modification of polymer phase change materials[J]. China Plastics Industry, 2022, 50(2): 1-5.
[5]	Delgado M, L􀅡zaro A, Mazo J, et al. Experimental analysis of a microencapsulated PCM slurry as thermal storage system and as heat transfer fluid in laminar flow[J]. Applied Thermal Engineering, 2012, 36: 370-377.
[6]	李建立, 刘录. 用于功能热流体的相变材料微胶囊力学性能研究进展[J]. 化工进展, 2015, 34(7): 1928-1932.
	Li J L, Liu L. Research progress in mechanical properties of microencapsulated phase change materials used as functional thermal fluid[J]. Chemical Industry and Engineering Progress, 2015, 34(7): 1928-1932.
[7]	Jin W Z, Huang Q H, Huang H M, et al. The preparation of a suspension of microencapsulated phase change material (MPCM) and thermal conductivity enhanced by MXene for thermal energy storage[J]. Journal of Energy Storage, 2023, 73: 108868.
[8]	冀林仙, 史晓滨, 郑保忠. 微胶囊悬浮剂稳定性研究[J]. 农业与技术, 2009, 29(3): 48-49.
	Ji L X, Shi X B, Zheng B Z. Study on stability of microcapsule suspending agent[J]. Agriculture & Technology, 2009, 29(3): 48-49.
[9]	Chen R, Ge X, Zhong Y, et al. Experimental study of phase change microcapsule-based liquid cooling for battery thermal management[J]. International Communications in Heat and Mass Transfer, 2023, 146: 106912.
[10]	López-Pedrajas D, Borreguero A M, Ramos F J, et al. Influence of the dispersion characteristics for producing thermoregulating nano phase change slurries[J]. Chemical Engineering Journal, 2023, 452: 139034.
[11]	Verma C, Goni L K M O, Yaagoob I Y, et al. Polymeric surfactants as ideal substitutes for sustainable corrosion protection: a perspective on colloidal and interface properties[J]. Advances in Colloid and Interface Science, 2023, 318: 102966.
[12]	Tadros T. Application of rheology for assessment and prediction of the long-term physical stability of emulsions[J]. Advances in Colloid and Interface Science, 2004, 108: 227-258.
[13]	Zhang G H, Zhao C Y. Thermal and rheological properties of microencapsulated phase change materials[J]. Renewable Energy, 2011, 36(11): 2959-2966.
[14]	Al-Shannaq R, Farid M, Al-Muhtaseb S, et al. Emulsion stability and cross-linking of PMMA microcapsules containing phase change materials[J]. Solar Energy Materials and Solar Cells, 2015, 132: 311-318.
[15]	Huang L, Petermann M, Doetsch C. Evaluation of paraffin/water emulsion as a phase change slurry for cooling applications[J]. Energy, 2009, 34(9): 1145-1155.
[16]	Han F, Cao M, Lin J L, et al. Selection of dispersant and dispersion mechanism of PVP on copper powders[J]. Colloid and Polymer Science, 2024, 302(3): 355-362.
[17]	Xue H J, Wang X M, Xu Q, et al. Adsorption of methylene blue from aqueous solution on activated carbons and composite prepared from an agricultural waste biomass: a comparative study by experimental and advanced modeling analysis[J]. Chemical Engineering Journal, 2022, 430: 132801.
[18]	Zhao X B, Han X Y, Yao Y P, et al. Stability investigation of propylene glycol-based Ag@SiO₂ nanofluids and their performance in spectral splitting photovoltaic/thermal systems[J]. Energy, 2022, 238: 122040.
[19]	Oliveira de Souza L, Cordazzo M, Silva de Souza L M, et al. Investigation of dispersion methodologies of microcrystalline and nano-fibrillated cellulose on cement pastes[J]. Cement and Concrete Composites, 2022, 126: 104351.
[20]	Doblas D, Kister T, Cano-Bonilla M, et al. Colloidal solubility and agglomeration of apolar nanoparticles in different solvents[J]. Nano Letters, 2019, 19(8): 5246-5252.
[21]	Devendiran D K, Amirtham V A. A review on preparation, characterization, properties and applications of nanofluids[J]. Renewable and Sustainable Energy Reviews, 2016, 60: 21-40.
[22]	Liu C Z, Rao Z H, Zhao J T, et al. Review on nanoencapsulated phase change materials: preparation, characterization and heat transfer enhancement[J]. Nano Energy, 2015, 13: 814-826.
[23]	Marrink S J, Risselada H J, Yefimov S, et al. The MARTINI force field: coarse grained model for biomolecular simulations[J]. The Journal of Physical Chemistry. B, 2007, 111(27): 7812-7824.
[24]	Ruiz-Morales Y, Romero-Martínez A. Coarse-grain molecular dynamics simulations to investigate the bulk viscosity and critical micelle concentration of the ionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution[J]. The Journal of Physical Chemistry. B, 2018, 122(14): 3931-3943.
[25]	Wei D W, Fang Y, Liu L, et al. On the intermolecular interactions and mechanical properties of polyvinyl alcohol/inositol supramolecular complexes[J]. Sustainable Materials and Technologies, 2024, 41: e00990.
[26]	Illa-Tuset S, Malaspina D C, Faraudo J. Coarse-grained molecular dynamics simulation of the interface behaviour and self-assembly of CTAB cationic surfactants[J]. Physical Chemistry Chemical Physics, 2018, 20(41): 26422-26430.
[27]	Rossi G, Giannakopoulos I, Monticelli L, et al. A MARTINI coarse-grained model of a thermoset polyester coating[J]. Macromolecules, 2011, 44(15): 6198-6208.
[28]	Liu C Z, Bao Y B, Huang K, et al. Experimental study on natural convection heat transfer performance of microencapsulated phase change material slurry in a square cavity[J]. Applied Thermal Engineering, 2025, 259: 124883.
[29]	Zhang J J, Zhu D L, Liu Y, et al. Experimental investigation of spray cooling heat transfer with microcapsule phase change suspension[J]. International Journal of Heat and Mass Transfer, 2024, 229: 125720.
[30]	Xiang H, He Z Y, Tang H J, et al. Healing behavior of thermo-oxygen aged asphalt based on molecular dynamics simulations[J]. Construction and Building Materials, 2022, 349: 128740.
[31]	Sun D L, Zhou J. Molecular simulation of oxygen sorption and diffusion in the poly(lactic acid)[J]. Chinese Journal of Chemical Engineering, 2013, 21(3): 301-309.
[32]	Santos A P, Panagiotopoulos A Z. Determination of the critical micelle concentration in simulations of surfactant systems[J]. The Journal of Chemical Physics, 2016, 144(4): 044709.
[33]	Gao C Q, Guo M Y, Liu Y K, et al. Surface modification methods and mechanisms in carbon nanotubes dispersion[J]. Carbon, 2023, 212: 118133.
[34]	Song S H, Koelsch P, Weidner T, et al. Sodium dodecyl sulfate adsorption onto positively charged surfaces: monolayer formation with opposing headgroup orientations[J]. Langmuir, 2013, 29(41): 12710-12719.
[35]	Wang W T, Zhang B G, Shi Y H, et al. Improvement in dispersion stability of alumina suspensions and corresponding chemical mechanical polishing performance[J]. Applied Surface Science, 2022, 597: 153703.
[36]	Chang X J, Henderson W M, Bouchard D C. Multiwalled carbon nanotube dispersion methods affect their aggregation, deposition, and biomarker response[J]. Environmental Science & Technology, 2015, 49(11): 6645-6653.