摘要
提出将脉动流引入平板型太阳能空气集热器,通过增加壁面切应力延缓集热器内部积灰速率,提升其长期工作性能。采用数值模拟手段评估了集热器内部积灰对集热性能的影响,探讨了入口正弦型脉动流脉动参数对集热器流动和传热特性的影响。结果表明:在脉动周期内,集热效率基本不随时间变化,除了在0.5~2 Hz小范围低频脉动工况,集热效率均没有超过稳态流动时的集热效率,并且随着无因次振幅和脉动频率的增大,集热效率呈下降趋势;全压损失只随无因次振幅的增大而增加,当无因次振幅增大到1时,全压损失约增加40%左右;平均壁面切应力随无因次振幅和脉动频率的增大而显著增大,当无因次振幅为1,脉动频率为10 Hz时,平均壁面切应力较稳态时可增大132.4%,这将有利于延缓积灰速率并减小积灰厚度,对集热器长期工作性能提升起到积极作用。
In this paper,pulsating flow was introduced into flat-plate solar air collector to increase the wall shear stress,decelerate the dust deposition inside the collector and improve long-term performance of flat-plate baffle-type solar air collector.Numerical simulation was used to evaluate the effect of dust deposition inside the collector on the heat collecting performance.The influence of fluctuating parameters on the flow and heat transfer characteristics of the collector was discussed.The results show that:the heat collecting efficiency of pulsating flow does not change with time during the pulsation period,and cannot exceed the efficiency of steady-state flow,except in the low-frequency pulsation condition ranging from 0.5~2 Hz.With the increase of non-dimensional amplitude and frequency,the heat collecting efficiency decreases.Total pressure loss increases with the increase of non-dimensional amplitude,and when the non-dimensional amplitude increases to 1,the total pressure loss increases by 40%.The average wall shear stress increases significantly with the increase of non-dimensional amplitude and pulsation frequency.When the non-dimensional amplitude is 1 and the pulsation frequency is 10 Hz,the average wall shear stress is increased by 132.4%compared with the calculation results of steady state,which could contribute to delaying dust deposition rate and reducing the thickness of deposition,and in turn having positive effect on the long-term performance of the flat-plate solar air collector.
作者
胡建军
李萌蒙
王美达
褚中良
HU Jian-jun;LI Meng-meng;WANG Mei-da;CHU Zhong-liang(School of Civil Engineering Mechanics,Yanshan University,Qinhuangdao,China,Post code:066004)
出处
《热能动力工程》
CAS
CSCD
北大核心
2019年第8期147-155,共9页
Journal of Engineering for Thermal Energy and Power
基金
国家自然科学基金(51705446,51890881)~~
关键词
空气集热器
内部积灰
脉动流
壁面切应力
solar air collector
dust deposition
pulsating flow
wall shear stress
