CIESC Journal ›› 2025, Vol. 76 ›› Issue (3): 1275-1287.DOI: 10.11949/0438-1157.20240873

• Energy and environmental engineering • Previous Articles     Next Articles

Effect of structural parameters on heat storage characteristics of indirect solar hot water storage tank

Xiang XU(), Zhonghe HAN(), Hengfan LI   

  1. Hebei Provincial Key Laboratory of Low-Carbon and High-efficiency Power Generation Technology, North China Electric Power University, Baoding 071003, Hebei, China
  • Received:2024-08-01 Revised:2024-09-29 Online:2025-03-28 Published:2025-03-25
  • Contact: Zhonghe HAN

结构参数对间接式太阳能储热水箱蓄热特性影响

许翔(), 韩中合(), 李恒凡   

  1. 华北电力大学河北省低碳高效发电技术重点实验室,河北 保定 071003
  • 通讯作者: 韩中合
  • 作者简介:许翔(1998—),男,硕士研究生,x15549482969@163.com
  • 基金资助:
    北京市自然科学基金项目(3232037)

Abstract:

The hot water tank in the solar heating system solves the problem of intermittent solar radiation and does not match the heat load. However, severe thermal stratification and mixing of hot and cold water in conventional thermal storage tanks hinder their ability to provide high-quality hot water, limiting the widespread deployment of solar heating systems. To enhance the thermal storage performance of these tanks, a mathematical model for the thermal storage process was established, and three-dimensional numerical simulations were employed to calculate the thermal storage characteristics, using the thickness of the thermocline layer and thermal storage capacity as performance indicators. The thermal storage characteristics of tanks with different configurations were analyzed using parameters such as the Nusselt number and the exergy. The research findings indicate that the original tank design with a bottom-mounted heat exchanger and no vertical pipe experienced the most severe water mixing, while a top-mounted heat exchanger yielded the best stratification effect but had a lower thermal storage capacity. Integrating a bottom-mounted heat exchanger with a vertical pipe significantly improved the stratification and thermal storage capacity of the tank. With this configuration, the tank’s thermal storage capacity increased by 18.87% within 3600 s, and the exergy increased by 1322.14%. The pump flow rate, vertical pipe height, and pipe diameter all influenced the tank’s thermal storage capacity and stratification effect. Optimal overall performance was achieved with a pump flow rate of 0.25 kg/s and a vertical pipe height and diameter of 1300 mm and 100 mm, respectively.

Key words: hot water storage tank, indirect heat exchange, temperature stratification, structural parameters, heat storage characteristic

摘要:

太阳能采暖系统中的储热水箱解决了太阳辐射间歇性和用热负荷不匹配的问题,但传统水箱内冷热水掺混严重,限制了系统的广泛应用。针对新型空气源热泵微通道太阳能集热器系统,建立了储热水箱间接式非稳态蓄放热过程模型并提出优化方案。三维数值模拟分析了优化前后储热水箱的蓄热特性,研究了不同结构水箱在蓄热过程中的斜温层厚度、蓄热能力、Nusselt数及㶲量变化。研究显示,下置换热单元且无竖管的原结构水箱水体掺混最严重,上置换热单元分层效果最佳但蓄热能力差;下置换热单元配合竖管显著提升分层效果及蓄热能力,3600 s内蓄热能力提高18.87%,㶲量增加1322.14%。优化方案中,当水泵流速0.25 kg/s、竖管高度1300 mm、直径100 mm时,储热水箱综合性能最佳。

关键词: 储热水箱, 间接式换热, 温度分层, 结构参数, 蓄热特性

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