Heat discharging and natural convection heat transfer performance of coil heat exchanger in single molten salt tank. (5th February 2020)

• Record Type: Journal Article
• Authors: Zhang, Cancan; Shi, Suli; Lu, Yuanwei; Qiang, Yu; Wu, Yuting; Ma, Chongfang
• Is Part Of: Applied thermal engineering. Volume 166(2019)
• Publication Date: 2020-02-05
• Subjects: Coil heat exchanger -- Heat discharging -- Single thermal storage tank -- Natural convection; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2019.114689
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Effect of the coil heat exchanger arrangements was studied by simulation. The optimal arrangement of coil heat exchanger for heat discharging is obtained in single thermal storage tank. Flow velocity across heat exchanger is the key mechanism to improve heat discharging performance. Natural convection correlation of molten salt around coil heat exchanger can be expressed as: Nu = 0.165 p d 1.420 H c Z c - 1.163 R a 0.252 . Abstract: There has been an increasing attention on single-tank thermal energy storage, attracted by the low cost, high efficiency and compactness in the operation. The most researches on single-tank thermal energy storage focused on temperature stratification to improve its heat discharging efficiency using water as heat storage media. The present research aims at investigating heat discharging performance by improving natural convection heat transfer of molten sat around coil heat exchanger in single heat storage tank. The effect of different parameters of the coil heat exchanger on the heat discharging performance, flow field and temperature distribution are analyzed and discussed in the single molten salt tank. The results show that the heat discharging performance of the coil heat exchanger can be enhanced by increasing the buoyancy-driven flow around the coil heat exchanger. The heat discharging efficiency can be improved by the optimal arrangement of coil heat exchanger for the highest velocity can be induced around it, which results in a fully mixed of molten salts and its temperature turns to uniform, instead of temperature stratification. Based on the results, a correlation among the natural convection Nu number with Ra number and other heat exchanger parameters in a single molten salt tank is obtained by numerical results. The research results provide a theoretical basis and paradigm for the design of single thermal storage tank energy storage system.