Numerical study on charging/discharging characteristics of a closed thermochemical reactor based on SrBr2·6H2O

doi:10.19799/j.cnki.2095-4239.2025.0172

Abstract

Abstract:

To investigate the energy storage and release characteristics of a closed thermochemical reactor utilizing SrBr₂·6H₂O, a three-dimensional transient coupled model integrating fluid flow, heat transfer, and thermochemical reactions was established. The model was employed to analyze variations in temperature, conversion rate, and heat transfer fluid (HTF) outlet temperature during the energy storage and release processes. The effects of different fin configurations on thermal performance were compared, and the influences of HTF temperature, HTF flow velocity, and water vapor pressure on reactor performance were systematically examined. The results indicate that radial heat transfer within the reactor is constrained by the low thermal conductivity of the thermochemical energy storage material (TCM). Fins accelerate reaction rates and improve the thermal grade of the heated fluid during discharge. Under equivalent surface area conditions, longitudinal fins exhibit superior heat transfer enhancement and energy storage/release performance compared to radial fins. Specifically, the storage and discharge times of the longitudinal fin reactor are reduced by 36.96% and 35.97%, respectively, while those of the radial fin reactor are reduced by 20.74% and 20.07%, respectively, relative to the nonfin reactor. HTF temperature and water vapor pressure exert significant impacts. An increase in HTF temperature promotes the charging process, reducing the charging time by 59.94% and increasing the charging power. However, it inhibits the discharging process, increasing the discharging time by 65.26% and decreasing the discharging power. Conversely, higher water vapor pressure hinders the energy storage process and facilitates energy release, increasing the energy storage time by 40.83% and reducing the energy release time by 84.39%. Although increasing HTF flow velocity enhances heat transfer between TCM and HTF and accelerates the charging and discharging processes, its influence is less pronounced, reducing the charging and discharging times by only 14.14% and 5.91%, respectively. These findings provide valuable guidance for the practical application of closed hydrated salt thermochemical reactors.

Key words: thermochemical energy storage, SrBr₂·6H₂O, fin, heat and mass transfer

CLC Number:

TK 02

Chengchen LI, Qinghua YU, Huitao DAI, Na JIA, Lin WANG, Binbo SUN. Numerical study on charging/discharging characteristics of a closed thermochemical reactor based on SrBr₂·6H₂O[J]. Energy Storage Science and Technology, 2025, 14(9): 3319-3329.

Figures/Tables 15

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References 19

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符号	描述	数值
H	反应盐层高度	400 mm
δ	反应盐层厚度	25 mm
d	HTF管内径	16 mm
D	HTF管外径	20 mm
L	HTF管间距	80 mm

参数	物理意义	数值
A_f	指前因子	16300 1/s
E_a	反应活化能	55000 J/mol
R	理想气体常数	8.314 J/(mol·K)
ΔH	反应焓	67400 J/mol
ΔS	反应熵	175 J/(mol·K)
ε	孔隙率	0.75
d_p	颗粒直径	0.001 m
χ	化学反应计量数	5
c_p_,hyd	SrBr₂·6H₂O比热容	967 J/(kg·K)
c_p_,deh	SrBr₂·H₂O比热容	456 J/(kg·K)
λ_hyd	SrBr₂·6H₂O热导率	0.71 W/(m·K)
λ_deh	SrBr₂·H₂O热导率	0.56 W/(m·K)
ρ_hyd	SrBr₂·6H₂O密度	2386 kg/m³
ρ_deh	SrBr₂·H₂O密度	3911 kg/m³
M_hyd	SrBr₂·6H₂O摩尔质量	0.35549 kg/mol
M_deh	SrBr₂·H₂O摩尔质量	0.26544 kg/mol
M_v	H₂O摩尔质量	0.01802 kg/mol
p_ref	参考压力	101325 Pa
p_c/e	冷凝/蒸发压力	2340 Pa
T_in,ch	储能过程HTF温度	353.15 K
T_in,dis	放能过程HTF温度	293.15 K
T_0,ch	储能过程初始温度	326.66 K
T_0,dis	放能过程初始温度	293.15 K
u_in	HTF流速	0.01 m/s

Numerical study on charging/discharging characteristics of a closed thermochemical reactor based on SrBr₂·6H₂O

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