Experiment on the unconstrained melting of paraffin in spherical containers

doi:10.11949/j.issn.0438-1157.20181341

Abstract

Abstract:

A visualization experiment is conducted to investigate the unconstrained melting process of phase change material (PCM, paraffin RT27) with void in a spherical container. Factors including the spherical container diameter, the heating temperature, the initial temperature and the filling ratio of PCM are discussed. Melting behaviors including the solid-liquid interface evolution and the solid PCM motion are revealed, in which a melting mode of floating melting following by close-contact melting is observed due to the existence of void in the spherical container. The quantitative results show that as the spherical container diameter increases, the floating melting time increase first and then decreases, while the total melting time shows a continually increasing trend. Increasing heating temperature or increasing initial temperature will decrease the floating melting time and total melting time. With the increases of PCM filling ratio, the PCM floating melting time and the total melting time increase first and then decrease. Finally, a dimensionless total melting time correlation in terms of Rayleigh number, Stefan number, filling ratio of PCM and dimensionless initial temperature is proposed.

Key words: phase change, multiphase flow, heat transfer, thermal energy storage, unconstrained melting, void, spherical container

摘要：

通过可视化实验研究了球内受空隙影响的石蜡（RT27）非约束融化过程，探讨了球直径、加热温度、初始温度以及相变材料（PCM）填充率对球内非约束融化特性的影响。通过对PCM固液界面演化、固相运动等融化行为的观察发现，受球内空隙影响，非约束融化过程会出现固相PCM先漂浮后下沉的融化模式。进一步的量化结果表明：增大球直径，固相PCM漂浮时间先增大后减小，总融化时间则持续增大；提升加热温度和初始温度，固相PCM漂浮时间和总融化时间减小；增大PCM填充率，固相漂浮时间和总融化时间先增大后减小。最后，通过对实验数据的无量纲化分析，提出了无量纲总融化时间（受Rayleigh数、Stefan数、PCM填充率、无量纲初始温度影响）关系式。

关键词: 相变, 多相流, 传热, 热能存储, 非约束融化, 空隙, 球形容器

CLC Number:

TK 124

Zeshi GAO, Yuanpeng YAO, Huiying WU. Experiment on the unconstrained melting of paraffin in spherical containers[J]. CIESC Journal, 2019, 70(7): 2480-2487.

高泽世, 姚元鹏, 吴慧英. 球形容器内石蜡非约束融化特性实验[J]. 化工学报, 2019, 70(7): 2480-2487.

Figures/Tables 12

Fig.1 Sectional view of cone-shaped void in spherical phase change unit[31]

Fig.2 Experimental setup for unconstrained melting of PCM inside spherical container

Table 1 Thermophysical properties of RT27[27]

热物性参数	数值
密度 (固相), ρ_s/（kg/m³）	880
密度 (液相), ρ_l/（kg/m³）	760
热导率 (固相), λ_s/(W/(m·℃))	0.24
热导率 (液相), λ_l/(W/(m·℃))	0.15
比热容 (固相), c_s/(kJ/(kg·℃))	2.4
比热容 (液相), c_l/(kJ/(kg·℃))	1.8
热膨胀系数 (液相), β/℃^-1	5×10^-4
运动黏度, ν/(m²/s)	5×10^-6
潜热, L/(kJ/kg)	179
相变温度, T_m/℃	27

Table 2 Spherical container samples

直径/mm	PCM质量,M₀/g	球壳质量/g
20.05	2.787	1.331
30.70	10.861	2.397
40.75	26.522	4.219
50.10	48.990	9.840
60.10	79.996	13.093
70.30	131.592	14.627

Fig.3 Unconstrained melting process in a sphere(D = 40.75 mm, Th = 37℃, Ti= 7℃, ε=0.90)

Fig.4 Schematic diagram of floating and sinking of solid PCM

Fig.5 Variation of float melting time (a) and total melting time (b) with diameter and heating temperature

Fig.6 Variation of float melting time (a) and total melting time (b) with PCM filling ratio

Fig.7 Variation of float melting time (a) and total melting time (b) with initial temperature

Table 3 Errors of dimensionless parameters

参数	相对误差/%
Ra	8
Ste	2.8
S_i	2.8
Fo	7.1
ε	0.1

Fig.8 Correlation between dimensionless total melting time and dimensionless floating melting time

Fig.9 Correlation of dimensionless total melting time

References 32

1	ZalbaB, Marı́nJ M, CabezaL F, et al. Review on thermal energy storage with phase change: materials, heat transfer analysis and applications[J]. Applied Thermal Engineering, 2003, 23(3): 251-283.
2	NomuraT, AkiyamaT. High-temperature latent heat storage technology to utilize exergy of solar heat and industrial exhaust heat[J]. International Journal of Energy Research, 2017, 41(2): 240-251.
3	ReginA F, SolankiS C, SainiJ S. Heat transfer characteristics of thermal energy storage system using PCM capsules: a review[J]. Renewable and Sustainable Energy Reviews, 2008, 12(9): 2438-2458.
4	李明广, 张洋, 李月锋, 等. 相变蓄热单元的研究进展[J]. 材料研究与应用, 2011, 5(2): 77-81.
	LiM G, ZhangY, LiY F, et al. Research survey of phase-change thermal storage monomer[J]. Materials Research and Application, 2011, 5(2): 77-81.
5	姜益强, 齐琦, 姚杨, 等. 圆柱形壳管式相变蓄热单元的蓄热特性研究[J]. 太阳能学报, 2008, 29(1): 29-34.
	JiangY Q, QiQ, YaoY, et al. Study on thermal storage performance of PCM-based cylinder shell-and-tube energy storage cell[J]. Acta Energiae Solaris Sinica, 2008, 29(1): 29-34.
6	高泽世, 吴慧英. 水平圆柱相变单元蓄放热动态特性研究[J]. 工程热物理学报, 2014, 35(12): 2452-2456.
	GaoZ S, WuH Y. Study on heat charging and discharging characteristics of a horizontal cylinder phase change unit[J]. Journal of Engineering Thermophysics, 2014, 35(12): 2452-2456.
7	BouadilaS, FteïtiM, OueslatiM M, et al. Enhancement of latent heat storage in a rectangular cavity: solar water heater case study[J]. Energy Conversion and Management, 2014, 78: 904-912.
8	胡春妍, 袁艳平, 曹晓玲, 等. 环形单元内月桂酸熔化过程的传热特性[J]. 化工学报, 2014, 65(S2): 71-77.
	HuC Y, YuanY P, CaoX L, et al. Mechanism of heat transfer during melting of lauric acid in horizontal annulus[J]. CIESC Journal, 2014, 65(S2): 71-77.
9	LiW, WangY H, KongC C. Experimental study on melting/solidification and thermal conductivity enhancement of phase change material inside a sphere[J]. International Communications in Heat and Mass Transfer, 2015, 68: 276-282.
10	DhaidanN S, KhodadadiJ M. Melting and convection of phase change materials in different shape containers: a review[J]. Renewable and Sustainable Energy Reviews, 2015, 43: 449-477.
11	TanF L. Constrained and unconstrained melting inside a sphere[J]. International Communications in Heat and Mass Transfer, 2008, 35(4): 466-475.
12	FanL, ZhuZ, LiuM, et al. Heat transfer during constrained melting of nano-enhanced phase change materials in a spherical capsule: an experimental study[J]. Journal of Heat Transfer, 2016, 138(12): 122402.
13	刘闵婕, 朱子钦, 许粲羚, 等. 球形容器内复合相变材料的约束熔化传热过程[J]. 浙江大学学报(工学版), 2016, 50(3): 477-484.
	LiuM J, ZhuZ Q, XuC L, et al. Constrained melting heat transfer of composite phase change materials inside spherical container[J]. Journal of Zhejiang University (Engineering Science), 2016, 50(3): 477-484.
14	EttouneyH, AlatiqiI, Al-SahaliM, et al. Heat transfer enhancement in energy storage in spherical capsules filled with paraffin wax and metal beads[J]. Energy Conversion and Management, 2006, 47(2): 211-228.
15	朱子钦, 肖胜蓝, 施松鹤, 等. 相变材料在含翅片球形容器内的约束熔化传热过程[J]. 科学通报, 2015, 60(12): 1125-1131.
	ZhuZ Q, XiaoS L, ShiS H, et al. Constrained melting heat transfer of a phase change material in a finned spherical capsule[J]. Chinese Science Bulletin, 2015, 60(12): 1125-1131.
16	FanL W, ZhuZ Q, XiaoS L, et al. An experimental and numerical investigation of constrained melting heat transfer of a phase change material in a circumferentially finned spherical capsule for thermal energy storage[J]. Applied Thermal Engineering, 2016, 100: 1063-1075.
17	姚元鹏,刘振宇,吴慧英.一种计算泡沫金属等效热导率的新模型[J].化工学报, 2014, 65(8):2921-2926.
	YaoY P, LiuZ Y, WuH Y. A new model for calculating effective thermal conductivity of metal foam[J]. CIESC Journal, 2014, 65(8):2921-2926.
18	KhodadadiJ M, ZhangY. Effects of buoyancy-driven convection on melting within spherical containers[J]. International Journal of Heat and Mass Transfer, 2001, 44(8): 1605-1618.
19	TanF L, HosseinizadehS F, KhodadadiJ M, et al. Experimental and computational study of constrained melting of phase change materials (PCM) inside a spherical capsule[J]. International Journal of Heat and Mass Transfer, 2009, 52(15/16): 3464-3472.
20	VeerappanM, KalaiselvamS, IniyanS, et al. Phase change characteristic study of spherical PCMs in solar energy storage[J]. Solar Energy, 2009, 83(8): 1245-1252.
21	GalioneP A, LehmkuhlO, RigolaJ, et al. Fixed-grid numerical modeling of melting and solidification using variable thermo-physical properties-application to the melting of n-octadecane inside a spherical capsule[J]. International Journal of Heat and Mass Transfer, 2015, 86: 721-743.
22	SattariH, MohebbiA, AfsahiM M, et al. CFD simulation of melting process of phase change materials (PCMs) in a spherical capsule[J]. International Journal of Refrigeration, 2017, 73: 209-218.
23	林琦, 王树刚, 王继红, 等. 球形胶囊内约束熔化过程的LBM模拟[J]. 化工学报, 2018, 69(6): 2373-2379.
	LinQ, WangS G, WangJ H, et al. Numerical simulation of constrained melting inside spherical capsule by lattice Boltzmann method[J]. CIESC Journal, 2018, 69(6): 2373-2379.
24	AminN A M, BrunoF, BeluskoM. Effective thermal conductivity for melting in PCM encapsulated in a sphere[J]. Applied Energy, 2014, 122: 280-287.
25	LiaoZ, XuC, RenY, et al. A novel effective thermal conductivity correlation of the PCM melting in spherical PCM encapsulation for the packed bed TES system[J]. Applied Thermal Engineering, 2018, 135: 116-122.
26	MooreF E, BayazitogluY. Melting within a spherical enclosure[J]. Journal of Heat Transfer, 1982, 104(1): 19-23.
27	AssisE, KatsmanL, ZiskindG, et al. Numerical and experimental study of melting in a spherical shell[J]. International Journal of Heat and Mass Transfer, 2007, 50(9/10): 1790-1804.
28	张鲁燕, 郝学军, 宋孝春, 等. 蓄冷冰球非固定融化的数值模拟[J]. 区域供热, 2018,(1): 92-97.
	ZhangL Y, HaoX J, SongX C, et al. Numerical simulation on the process of ambulatory melting in storage sphere[J]. District Heating, 2018,(1): 92-97.
29	HosseinizadehS F, Rabienataj DarziA A, TanF L, et al. Unconstrained melting inside a sphere[J]. International Journal of Thermal Sciences, 2013, 63: 55-64.
30	BlaneyJ J, NetiS, MisiolekW Z, et al. Containment capsule stresses for encapsulated phase change materials[J]. Applied Thermal Engineering, 2013, 50(1): 555-561.
31	AssisE, ZiskindG, LetanR. Numerical and experimental study of solidification in a spherical shell[J]. Journal of Heat Transfer, 2008, 131(2): 024502.
32	BondarevaN S, SheremetM A. 3D natural convection melting in a cubical cavity with a heat source[J]. International Journal of Thermal Sciences, 2017, 115: 43-53.

[1]	Shuangxing ZHANG, Fangchen LIU, Yifei ZHANG, Wenjing DU. Experimental study on phase change heat storage and release performance of R-134a pulsating heat pipe [J]. CIESC Journal, 2023, 74(S1): 165-171.
[2]	Yifei ZHANG, Fangchen LIU, Shuangxing ZHANG, Wenjing DU. Performance analysis of printed circuit heat exchanger for supercritical carbon dioxide [J]. CIESC Journal, 2023, 74(S1): 183-190.
[3]	Aiqiang CHEN, Yanqi DAI, Yue LIU, Bin LIU, Hanming WU. Influence of substrate temperature on HFE7100 droplet evaporation process [J]. CIESC Journal, 2023, 74(S1): 191-197.
[4]	Mingxi LIU, Yanpeng WU. Simulation analysis of effect of diameter and length of light pipes on heat transfer [J]. CIESC Journal, 2023, 74(S1): 206-212.
[5]	Zhiguo WANG, Meng XUE, Yushuang DONG, Tianzhen ZHANG, Xiaokai QIN, Qiang HAN. Numerical simulation and analysis of geothermal rock mass heat flow coupling based on fracture roughness characterization method [J]. CIESC Journal, 2023, 74(S1): 223-234.
[6]	He JIANG, Junfei YUAN, Lin WANG, Guyu XING. Experimental study on the effect of flow sharing cavity structure on phase change flow characteristics in microchannels [J]. CIESC Journal, 2023, 74(S1): 235-244.
[7]	Yanpeng WU, Qianlong LIU, Dongmin TIAN, Fengjun CHEN. A review of coupling PCM modules with heat pipes for electronic thermal management [J]. CIESC Journal, 2023, 74(S1): 25-31.
[8]	Siyu ZHANG, Yonggao YIN, Pengqi JIA, Wei YE. Study on seasonal thermal energy storage characteristics of double U-shaped buried pipe group [J]. CIESC Journal, 2023, 74(S1): 295-301.
[9]	Cheng CHENG, Zhongdi DUAN, Haoran SUN, Haitao HU, Hongxiang XUE. Lattice Boltzmann simulation of surface microstructure effect on crystallization fouling [J]. CIESC Journal, 2023, 74(S1): 74-86.
[10]	Ruitao SONG, Pai WANG, Yunpeng WANG, Minxia LI, Chaobin DANG, Zhenguo CHEN, Huan TONG, Jiaqi ZHOU. Numerical simulation of flow boiling heat transfer in pipe arrays of carbon dioxide direct evaporation ice field [J]. CIESC Journal, 2023, 74(S1): 96-103.
[11]	Yitong LI, Hang GUO, Hao CHEN, Fang YE. Study on operating conditions of proton exchange membrane fuel cells with non-uniform catalyst distributions [J]. CIESC Journal, 2023, 74(9): 3831-3840.
[12]	Yubing WANG, Jie LI, Hongbo ZHAN, Guangya ZHU, Dalin ZHANG. Experimental study on flow boiling heat transfer of R134a in mini channel with diamond pin fin array [J]. CIESC Journal, 2023, 74(9): 3797-3806.
[13]	Ke LI, Jian WEN, Biping XIN. Study on influence mechanism of vacuum multi-layer insulation coupled with vapor-cooled shield on self-pressurization process of liquid hydrogen storage tank [J]. CIESC Journal, 2023, 74(9): 3786-3796.
[14]	Cong QI, Zi DING, Jie YU, Maoqing TANG, Lin LIANG. Study on solar thermoelectric power generation characteristics based on selective absorption nanofilm [J]. CIESC Journal, 2023, 74(9): 3921-3930.
[15]	Yue YANG, Dan ZHANG, Jugan ZHENG, Maoping TU, Qingzhong YANG. Experimental study on flash and mixing evaporation of aqueous NaCl solution [J]. CIESC Journal, 2023, 74(8): 3279-3291.