采用不同传热工质的锥形腔式吸热器传热特性对比分析

doi:10.12096/j.2096-4528.pgt.21096

摘要/Abstract

摘要：

为探究传热工质对太阳能吸热器传热特性的影响，利用光线追踪和计算流体动力学方法，对采用超临界CO₂和压缩空气作为传热工质的锥形腔体吸热器的传热特性进行对比分析。基于数值模拟讨论了吸热器锥角、工质进口流量和进口温度对吸热器传热性能的影响规律。结果表明：相同工况下，压缩空气的出口温度比超临界CO₂高，但相应的吸热器热效率和系统光热转化效率却较低。对于2种传热工质，系统光热转化效率均在锥角为4.12°时取得最优值。在研究的运行参数范围内，传热工质的出口温度随进口温度的增加呈线性增长；当流量超过0.04 kg/s时，继续增大流量对提高系统光热转化效率作用较小。

关键词: 太阳能, 吸热器, 超临界CO₂, 压缩空气, 传热特性

Abstract:

To explore the influence of heat transfer fluids on the heat transfer characteristics of solar receivers, the heat transfer characteristics of conical cavity receivers with supercritical CO₂ and compressed air as heat transfer fluids were compared and analysed by combining ray tracing and computational fluid dynamics method. Based on numerical simulation, the effects of cone angle, fluid inlet mass flow rate and inlet temperature on heat transfer performance of receivers were discussed. The results show that under the same working conditions, the outlet temperature of compressed air is higher than that of supercritical CO₂, but the corresponding receiver thermal efficiency and system photothermal conversion efficiency are lower. For the two heat transfer fluids, the system photothermal conversion efficiencies reach the optimal values with the cone angle of 4.12°. In the range of operating parameters studied, the outlet temperature of heat transfer fluids increase linearly with the increase of inlet temperature. Once the mass flow rate exceeds 0.04 kg/s, increasing the mass flow rate has little effect on improving the photothermal conversion efficiency of the system.

Key words: solar energy, receiver, supercritical CO₂, compressed air, heat transfer characteristics

中图分类号:

TK513

王鼎, 陈宇轩, 肖虎, 张燕平. 采用不同传热工质的锥形腔式吸热器传热特性对比分析[J]. 发电技术, 2021, 42(6): 682-689.

Ding WANG, Yuxuan CHEN, Hu XIAO, Yanping ZHANG. Comparative Analysis of Heat Transfer Characteristics of Conical Cavity Receivers With Different Heat Transfer Fluids[J]. Power Generation Technology, 2021, 42(6): 682-689.

图/表 13

图1 腔体吸热器和PDC系统示意图

Fig.1 Schematic diagram of cavity receiver and PDC system

图2 计算域网格划分

Fig.2 Computational domain meshing

表1 网格无关性验证

Tab. 1 Grid independence check

网格数量	出口温度/K	绝对误差/%
2 423 370	860.40	0.24
3 598 505	861.09	0.16
4 442 491	862.60	0.00
5 630 989	862.52	—

图3 传热模拟结果对比验证

Fig.3 Comparison and verification of heat transfer simulation results

图4 吸热器盘管外壁面热流密度分布

Fig.4 Heat flux distribution on outer wall of receiver coil tube

表2 不同锥角下腔内吸收总能量和光学效率

Tab. 2 Total energy absorbed by the cavity and optical efficiency under different cone angles

ϕ/(°)	Q_ab/W	η_op/%
0	10 387	88.21
4.12	10 347	87.88
8.23	10 318	87.62
12.35	10 308	87.54
16.46	10 293	87.42

图5 不同锥角下HTF温度沿管长中心线的变化

Fig.5 Variation of HTF temperature along the centerline of the tube under different cone angles

图6 吸热器各项热损失随锥角的变化

Fig.6 Variations of heat losses of the receiver with different cone angles

图7 吸热器热效率和系统光热转化效率随锥角的变化

Fig.7 Variations of receiver thermal efficiency and system photothermal conversion efficiency with different cone angles

图8 吸热器各项热损失随进口流量的变化

Fig.8 Variations of heat losses of the receiver with different inlet mass flow rates

图9 HTF出口温度和系统光热转化效率随进口流量的变化

Fig.9 Variations of HTF outlet temperature and system photothermal conversion efficiency with different inlet mass flow rates

图10 吸热器各项热损失随进口温度的变化

Fig.10 Variations of heat losses of the receiver with different inlet temperatures

图11 HTF出口温度和系统光热转化效率随进口温度的变化情况

Fig.11 Variations of HTF outlet temperature and system photothermal conversion efficiency with different inlet temperatures

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