Storage and release characteristics of seasonal composite thermal storage system

doi:10.19799/j.cnki.2095-4239.2020.0101

Abstract

Abstract:

Renewable energy sources, such as solar energy, have the characteristics of intermittence and instability that lead to their temporal, spatial, and intensity mismatch and seasonal characteristics. The seasonal thermal storage technology is one of the most effective solutions for these problems, but the traditional seasonal thermal storage system encounters problems of large heat loss and low system efficiency. To solve these problems, this study proposes a new type of composite thermal storage system coupled with an underground borehole storage and a water tank thermal storage. This system uses Fluent simulation software to perform research on the thermal storage and release characteristics of the composite thermal storage system and the change law of the temperature field of the thermal storage body. The results show that the new composite thermal storage system is technically feasible with a 67.29% system efficiency. The two thermal storage methods are complementary and coordinate with each other. The temperature fields of the coupled thermal storage bodies are superimposed on each other, thereby showing a significant temperature delay, and are more conducive to the thermal storage and release. In addition, after one operating cycle of the composite thermal storage system, the temperature level of the coupled thermal storage body increases, which is conducive to the system operation for many years. This research will be helpful in expanding and improving the energy transmission and heat transfer control theory of the underground seasonal thermal storage system and provide theoretical guidance for further expansion and application.

Key words: thermal storage technology, seasonal thermal storage, thermal storage/release characteristics, heat loss

CLC Number:

TK 52

Ziyi WANG, Yujie XU, Xuezhi ZHOU, Haisheng CHEN, Young SHENG, Dehou XU, Youqiang LINGHU, Jie DING. Storage and release characteristics of seasonal composite thermal storage system[J]. Energy Storage Science and Technology, 2020, 9(6): 1837-1846.

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网格编号	1	2	3
网格总数/万	24.2	30.8	35.6
释热量/MJ	1011	1035	1044

参数	取值
土壤导热系数/W·(m·k)^-1	1.9
土壤密度/kg·m^-3	2000
土壤比热容/J·(kg·k)^-1	700
U型管导热系数/W·(m·k)^-1	0.44
U型管密度/kg·m^-3	950
U型管比热容/J·(kg·k)^-1	2300
水箱导热系数/W·(m·k)^-1	59.41
水箱密度/(kg·m^-3)	7860
水箱比热容/J·(kg·k)^-1	468.61
水导热系数/W·(m·k)^-1	0.6
水的密度/kg·m^-3	998
水比热容/J·(kg·k)^-1	4182
水的黏度/N·s·m^-2	0.001