Heat transfer performance study of wedge-shaped shell-and-tube heat storage tank

doi:10.19799/j.cnki.2095-4239.2022.0270

Abstract

Abstract:

It is crucial to optimize the efficient thermal storage structure of thermal storage systems to address the problem of slow thermal response of phase change materials (PCMs) in conventional rectangular shell-and-tube phase change thermal storage systems. Numerical simulations were employed to examine the melting process of PCM with natural convection in a baseline shell-and-tube phase change thermal storage unit and an optimized structural unit and to perform experimental verification. According to different improved natural convection approaches, such as wedging, internal flow tube eccentricity, and inclined tanks, discuss the evolution of temperature field, heat storage capacity, Fo number, average Nu number, and phase interface. The dynamic thermal behavior of PCM within different improved natural convection approaches was examined to derive optimized solutions for enhancing the heat transfer efficiency of heat storage systems. The findings reveal that the wedge-shaped phase change heat storage unit shell shape can improve the natural convection effect and enhances the heat transfer performance. The complete melting time was reduced by 28% compared to the melting time of the PCM in the reference rectangular structure when the wedge ratio X=5. Although it prolongs the complete melting time and has an opposite effect on the melting efficiency, the eccentric distance has little effect on the heat storage capacity of the PCM in the vertically placed thermal storage system. The research findings have a certain reference significance for the realization of energy conservation and emission reduction and the realization of the dual carbon goal, where the natural convection heat transfer effect reaches its maximum during the early melting, and the heat storage efficiency increases to its maximum, with a 29% increase compared to vertical placement when the wedge-shaped tank is tilted at 75°.

Key words: enhanced heat transfer, natural convection, PCM, wedge-shaped

CLC Number:

TQ 051.5

Qianjun MAO, Kaili CHEN. Heat transfer performance study of wedge-shaped shell-and-tube heat storage tank[J]. Energy Storage Science and Technology, 2022, 11(11): 3658-3666.

Figures/Tables 10

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物理量	测试条件	模拟方法	数值
密度	303～353 K	Boussinesq	885 kg/m³
比热容	303～353 K	Piecewise-linear	303 K: 7103 J/(kg·K); 313 K: 3085 J/(kg·K); 323 K: 11530 J/(kg·K) 333 K: 2097 J/(kg·K); 343 K: 2106 J/(kg·K); 353 K: 2130 J/(kg·K)
热导率	303～353 K	Constant	0.279 W/(m·K)
动态黏度	/	Constant	1.72e-05 kg/(m·s)
热膨胀系数	/	Constant	0.0006 K^-1
相变潜热	253～363 K	Constant	172620 J/kg
固相温度	253～363 K	Constant	302 K
液相温度	253～363 K	Constant	322 K

楔形比X	切体高度S/mm	系统高度H/mm	完全熔化时间T/min	熔化时间缩短比率
0	0	350	750	/
1	50	361.3	833	-11%
2	100	372.5	930	-24%
3	150	383.8	730	2.6%
4	200	395.1	690	8%
5	250	406.3	540	28%
6	300	417.6	640	14.7%
7	350	428.8	690	8%

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