Preparation and investigation of the thermal charging and discharging of modified magnesium nitrate hexahydrate composite phase change material

doi:10.11949/0438-1157.20201543

Abstract

Abstract:

The hydrated salt phase change material has a wide range of application prospects in the field of medium and low temperature heat storage due to its high phase change enthalpy and low cost, but it usually has the problems of large subcooling and poor thermal cycle stability in the process of heat storage and release. Here, a modified magnesium nitrate hexahydrate is prepared as composite phase change material (PCM) for thermal energy storage, and the high-performance heat storage device using the modified PCM is designed and fabricated. The magnesium nitrate hexahydrate is modified by using calcium sulfate dihydrate as nucleating agent to synthesize composite PCM. The thermal properties and cycle thermal stability of the composite PCM are tested by differential scanning calorimeter (DSC) and thermal analysis method. Moreover, the composite PCM-based heat storage device and heating system with storage capacity of 152 kWh are designed and constructed, and their thermal performances are tested at different working conditions. The results show that the composite PCM with 2%(mass). Calcium sulfate dihydrate has good cycle thermal stability, and its supercooling degree can be kept within 0.5℃ after 50 melting-solidification cycles. The phase-change temperature is about 87℃ and the phase-change enthalpy is maintained above 150 kJ/kg. The PCM-based heat storage device achieves an average charging power up to 27 kW and discharging power of 8 kW. The thermal efficiency of heat storage-release is as high as 92.3%, and the heat storage device can ensure the outlet water temperature is higher than 56℃ during the heat release process, and thus can meet building heating and hot water.

Key words: hydrated salt, magnesium nitrate hexahydrate, heat storage, thermal stability

摘要：

水合盐相变材料因具有较高的相变焓和较低的成本在中低温储热领域有着广泛的应用前景，但其在储放热过程中通常存在过冷度大和热循环稳定性差的问题。以六水硝酸镁为主要研究对象开展相变储热复合材料的改性制备及相变储热装置的研制，采用熔融共混法制备了以二水硫酸钙为成核剂的六水硝酸镁相变储热复合材料，利用差示扫描量热仪及步冷曲线法测试了相变储热复合材料的热物性和循环热稳定性。在此基础上设计并构建了储热量为152 kWh的相变储热装置和相变储热系统，并对其储/放热性能进行了测试。结果表明：添加了2%（质量）二水硫酸钙的相变储热复合材料具有较好的循环热稳定性，且在经过50次熔化-凝固循环后其过冷度一直保持在0.5℃内，相变温度保持在87℃左右，相变焓保持在150 kJ/kg以上；相变储热装置可实现高达27 kW的平均储热功率，在保证放热过程中出水温度不低于56℃的情况下，可实现8 kW的平均放热功率和92.3%的储-放热效率，可满足建筑采暖及日常生活热水需求。

关键词: 无机盐, 六水硝酸镁, 储热, 热稳定性

CLC Number:

TK 124

GAO Jianchen, ZHAO Bingchen, HE Feng, LI Tingxian. Preparation and investigation of the thermal charging and discharging of modified magnesium nitrate hexahydrate composite phase change material[J]. CIESC Journal, 2021, 72(6): 3328-3337.

高剑晨, 赵炳晨, 何峰, 李廷贤. 六水硝酸镁相变储热复合材料改性制备及储/放热性能研究[J]. 化工学报, 2021, 72(6): 3328-3337.

Figures/Tables 12

Table 1 Lattice parameters of magnesium nitrate hexahydrate and calcium sulfate dihydrate

材料	a/?	b/?	c/?	α/(°)	β/(°)	γ/(°)	晶系
Mg(NO₃)₂·6H₂O	6.19	12.614	6.56	90	93.72	90	单斜
CaSO₄·2H₂O	5.67	15.201	6.533	90	118.6	90	单斜

Fig.1 Preparation of magnesium nitrate hexahydrate composite phase change material

Table 2 Component mass ratio of magnesium nitrate hexahydrate composite phase change material

材料	样品1	样品2	样品3	样品4
Mg(NO₃)₂·6H₂O	100%	99%	98%	97%
CaSO₄·2H₂O	0%	1%	2%	3%

Fig.2 Diagram of step cooling test device

Fig.3 Photograph and size of the MNH/CSD PCM-based heat storage device

Fig.4 Diagram of the MNH/CSD PCM -based heat storage system

Fig.5 DSC curves of MNH-based PCMs with different CSD contents before and after 50 cycles

Fig.6 Step cooling curve of MNH-based PCMs with different CSD contents

Fig.7 Thermal stability of MNH-based PCM with different content of nucleating agent

Fig.8 Thermal properties of MNH-based PCM with 2% CSD

Fig.9 Performance of the PCM-based heat storage device during thermal charging phase

Fig.10 Performance of the PCM-based heat storage device during thermal discharging phase

References 32

1	吴玉庭, 任楠, 马重芳. 熔融盐显热蓄热技术的研究与应用进展[J]. 储能科学与技术, 2013, 2(6): 586-592.
	Wu Y T, Ren N, Ma C F. Research and application of molten salts for sensible heat storage[J]. Energy Storage Science and Technology, 2013, 2(6): 586-592.
2	Zhang D L, Liu L M, Liu M H, et al. Review of conceptual design and fundamental research of molten salt reactors in China[J]. International Journal of Energy Research, 2018, 42(5): 1834-1848.
3	Li Q, Li C, Du Z, et al. A review of performance investigation and enhancement of shell and tube thermal energy storage device containing molten salt based phase change materials for medium and high temperature applications[J]. Applied Energy, 2019, 255: 113806.
4	Prieto C, Cooper P, Fernández A I, et al. Review of technology: thermochemical energy storage for concentrated solar power plants[J]. Renewable and Sustainable Energy Reviews, 2016, 60: 909-929.
5	Chen X Y, Zhang Z, Qi C G, et al. State of the art on the high-temperature thermochemical energy storage systems[J]. Energy Conversion and Management, 2018, 177: 792-815.
6	吴娟, 龙新峰. 太阳能热化学储能研究进展[J]. 化工进展, 2014, 33(12): 3238-3245.
	Wu J, Long X F. Research progress of solar thermochemical energy storage[J]. Chemical Industry and Engineering Progress, 2014, 33(12): 3238-3245.
7	Shao J J, Darkwa J, Kokogiannakis G. Review of phase change emulsions (PCMEs) and their applications in HVAC systems[J]. Energy and Buildings, 2015, 94: 200-217.
8	Shukla A, Buddhi D, Sawhney R L. Solar water heaters with phase change material thermal energy storage medium: a review[J]. Renewable and Sustainable Energy Reviews, 2009, 13(8): 2119-2125.
9	Sharma R K, Ganesan P, Tyagi V V, et al. Developments in organic solid-liquid phase change materials and their applications in thermal energy storage[J]. Energy Conversion and Management, 2015, 95: 193-228.
10	Tao Y B, He Y L. A review of phase change material and performance enhancement method for latent heat storage system[J]. Renewable and Sustainable Energy Reviews, 2018, 93: 245-259.
11	孟令然, 郭立江, 李晓禹, 等. 水合盐相变储能材料的研究进展[J]. 储能科学与技术, 2017, 6(4): 623-632.
	Meng L R, Guo L J, Li X Y, et al. Salt hydrate based phase change materials for thermal energy storage—a review[J]. Energy Storage Science and Technology, 2017, 6(4): 623-632.
12	Lin Y X, Alva G, Fang G Y. Review on thermal performances and applications of thermal energy storage systems with inorganic phase change materials[J]. Energy, 2018, 165: 685-708.
13	Donkers P A J, Sögütoglu L C, Huinink H P, et al. A review of salt hydrates for seasonal heat storage in domestic applications[J]. Applied Energy, 2017, 199: 45-68.
14	Wang Q, Wang J T, Chen Y Y, et al. Experimental investigation of barium hydroxide octahydrate as latent heat storage materials[J]. Solar Energy, 2019, 177: 99-107.
15	Fernandes D, Pitié F, Cáceres G, et al. Thermal energy storage: "How previous findings determine current research priorities"[J]. Energy, 2012, 39(1): 246-257.
16	Wang H, Guo L, Liu K, et al. Investigation of magnesium nitrate hexahydrate based phase change materials containing nanoparticles for thermal energy storage[J]. Materials Research Express, 2019, 6(10): 105512.
17	Nagano K, Ogawa K, Mochida T, et al. Thermal characteristics of magnesium nitrate hexahydrate and magnesium chloride hexahydrate mixture as a phase change material for effective utilization of urban waste heat[J]. Applied Thermal Engineering, 2004, 24(2/3): 221-232.
18	Rajamani P, Balasubramaniam M, Radhakrishnan K. Calorimetric investigation of magnesium nitrate hexahydrate and sodium thiosulphate pentahydrate as salt mixture encapsulated materials for thermal energy storage[J]. Thermal Science, 2020, 24(1 Part B): 613-621.
19	Rao Z H, Zhang G T, Xu T T, et al. Experimental study on a novel form-stable phase change materials based on diatomite for solar energy storage[J]. Solar Energy Materials and Solar Cells, 2018, 182: 52-60.
20	Salunkhe P B, D J K. Investigations on latent heat storage materials for solar water and space heating applications[J]. Journal of Energy Storage, 2017, 12: 243-260.
21	Lane G A. Phase change materials for energy storage nucleation to prevent supercooling[J]. Solar Energy Materials and Solar Cells, 1992, 27(2): 135-160.
22	Ding Q, Luo X G, Lin X Y, et al. Study of magnesium nitrate hexahydrate and magnesium chloride hexahydrate mixture as phase change material[C]//2012 Asia-Pacific Power and Energy Engineering Conference. Shanghai, 2012: 1-4.
23	谷海明. 相变储能材料Mg(NO₃)₂·6H₂O的稳定与储热性能研究[D]. 昆明: 昆明理工大学, 2013.
	Gu H M. Study on the stability and heat storage performance of phase change energy storage material Mg(NO₃)₂·6H₂O[D]. Kunming: Kunming University of Science and Technology, 2013.
24	Honcova P, Pilar R, Danielik V, et al. Suppressing supercooling in magnesium nitrate hexahydrate and evaluating corrosion of aluminium alloy container for latent heat storage application[J]. Journal of Thermal Analysis and Calorimetry, 2017, 129(3): 1573-1581.
25	Danielik V, Šoška P, Felgerová K, et al. The corrosion of carbon steel in nitrate hydrates used as phase change materials[J]. Materials and Corrosion, 2017, 68(4): 416-422.
26	Muthusivagami R M, Velraj R, Sethumadhavan R. Solar cookers with and without thermal storage—a review[J]. Renewable and Sustainable Energy Reviews, 2010, 14(2): 691-701.
27	Ali H M. Applications of combined/hybrid use of heat pipe and phase change materials in energy storage and cooling systems: a recent review[J]. Journal of Energy Storage, 2019, 26: 100986.
28	吴东灵, 李廷贤, 何峰, 等. 三水醋酸钠相变储能复合材料改性制备及储/放热特性[J]. 化工学报, 2018, 69(7): 2860-2868.
	Wu D L, Li T X, He F, et al. Preparation and performance of modified sodium acetate trihydrate composite phase change material for thermal energy storage[J]. CIESC Journal, 2018, 69(7): 2860-2868.
29	He Y, Zhang N, Yuan Y P, et al. Improvement of supercooling and thermal conductivity of the sodium acetate trihydrate for thermal energy storage with α-Fe₂O₃ as addictive[J]. Journal of Thermal Analysis and Calorimetry, 2018, 133(2): 859-867.
30	Liu C Z, Hu P B, Xu Z, et al. Experimental investigation on thermal properties of sodium acetate trihydrate based phase change materials for thermal energy storage[J]. Thermochimica Acta, 2019, 674: 28-35.
31	Naumann R, Emons H H. Results of thermal analysis for investigation of salt hydrates as latent heat-storage materials[J]. Journal of Thermal Analysis, 1989, 35(3): 1009-1031.
32	李廷贤, 王如竹, 何峰. 一种复合相变储热材料: 109609098A[P]. 2019.04.12.
	Li T X, Wang R Z, He F. Composite phase change heat storage material: 109609098A[P]. 2019.04.12.

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