Performance enhancement simulation of eccentric fractal-fin tube phase change heat storage unit

doi:10.19799/j.cnki.2095-4239.2022.0320

Abstract

Abstract:

To explore the mechanism of eccentric fractional-finned tubes improving the performance of phase change heat storage unit (PCCS), a two-dimensional unsteady simulation was conducted to study the melting of paraffin wax in the PCCS. The heat transfer characteristics of eccentric rectangular fin and eccentric fractal fin are compared considering natural convection. Demonstrating that the eccentric fractal fin enhances natural convection more than the eccentric rectangular fin and the temperature distribution is more uniform, which is consistent with the fact that the fractal fin can enhance heat diffusion from point to the surface, the partial strengthening of the eccentric fractal fin structure was conducted, and three schemes of rectangular fin, Y fin, and split fin were chosen. In the three local strengthening schemes, the eccentric fractal fin has the best strengthening impact, the melting rate is increased in the entire process, and the melting time is shortened by 70%. This offers good theoretical guidance for the performance enhancement of shell and tube phase change heat accumulators and further increases its application prospects in the field of energy storage.

Key words: phase change heat transfer, thermal storage unit, fractal fin, local reinforcement

CLC Number:

TK 02

Lijun LIU, Yaqian NING, Xiaoqing LI, Xiaoyan LIU. Performance enhancement simulation of eccentric fractal-fin tube phase change heat storage unit[J]. Energy Storage Science and Technology, 2022, 11(11): 3681-3687.

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特性	石蜡	铝
固相温度/K	324.15	2719
液相温度/K	330.15	—
固相密度/(kg/m³)	940	—
液相密度/(kg/m³)	760	—
比热容/[J/(kg·K)]	2100	871
相变潜热/(J/kg)	170000	—
热导率/[W/(m·K)]	0.25	202.4
热膨胀系数/K^-1	0.001	—
动力黏度/[kg/(m·s)]	0.00324	—

特性	n-eicosane
固相温度/K	308.15
液相温度/K	310.15
液相密度/(kg/m³)	770
比热容/[J/(kg·K)]	2460
相变潜热/(J/kg)	247600
热导率/[W/(m·K)]	0.1505
热膨胀系数/K^-1	0.0009
动力黏度/[kg/(m·s)]	0.00385

结构	熔化总时间/s
偏心矩形翅片结构	4000
偏心分形翅片结构	4400
偏心分形翅片强化结构	2600
偏心矩形翅片强化结构	3200
偏心Y形翅片强化结构	3190

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