System design and experimental study of Carnot battery based on latent heat/cold stores

doi:10.19799/j.cnki.2095-4239.2023.0314

Abstract

Abstract:

The Carnot battery system is a large-scale physical energy storage system that stores excess power in the form of heat energy and releases it outward through the power cycle when needed. It is free from geographical environment limitations, coMPact, and efficient, and has broad prospects in peak shaving, valley filling, and long-term energy storage. In this paper, a 10 MWh-class Carnot battery system was designed based on positive/reverse Brayton cycle and phase change heat storage technology.A numerical modelwas establishedbased on Python 3.8, and the influences of pressure ratio, isentropic efficiency, working fluid Reynolds number, medium length to diameter ratio, and other parameters on the system performance were explored.The results showed that the round-trip efficiency of the system could reach 0.6 when operating under the conditions of a compression ratio of 10 and isentropic efficiency of 0.9, and the energy storage and power density reached 378.44 kWh/m³ and 203.58 kW/m³, respectively. The energy storage process of the two tanks was experimentally studied under different operating parameters. It was verified that the greater the working fluid pressure at the entrance and the greater the difference between working and room temperatures, the higher the system's energy storage and power density.

Key words: Carnot battery system, phase change heat storage, dimensionless analysis, packed-bed, thermal storage performance

CLC Number:

TQ 028

Yanjun BO, Xinjie XUE, Huaning WANG, Changying ZHAO. System design and experimental study of Carnot battery based on latent heat/cold stores[J]. Energy Storage Science and Technology, 2023, 12(9): 2823-2832.

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参数/单位	储热罐	储冷罐
储能介质	NaOH粉末	质量分数15% CaCl₂水溶液
长度l/m	5	5
直径D/m	4	3
体积V/m³	121	81
压缩比β	10
等熵效率η	0.9
相变温度T_p/K	491	228
相变潜热L/(kJ/kg)	284	160
密度ρ/(kg/m³)	2130	1286
固态比热容c_p_,s/[kJ/(kg·K)]	2.9	2.6
液态比热容c_p_,l/[kJ/(kg·K)]	2.1	2
热导率λ/[W/(m·K)]	0.6	1.1

参数	储热罐	储冷罐
压力容器高度×外径×厚度/mm	800×662×12	650×512×6
相邻隔板间距/mm	250	200
储能介质单元体长度×宽度×高度/mm	150×150×200	100×100×150
容器个数/个	21	21
孔隙率	0.62	0.71

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