波纹结构换热壁面对微细通道流动沸腾不稳定性的影响

The Influence of Corrugated Heat Exchange Wall on the Instability of Flow Boiling in Micro Channels

为了研究波纹结构换热壁面对微细通道流动沸腾不稳定性的影响,设计安装微细通道流动沸腾不稳定性实验平台,加工制造了3个具有不同波纹结构换热壁面的微细通道,并进行关于换热介质R141b的相变沸腾换热实验。实验主要研究了热流密度、质量通量等变量对3个微细通道相变沸腾换热时进出口总压降波动的影响以及各个微细通道的总压降标准差的变化。结果表明:进出口总压降波动主要受到换热壁面波纹结构、热流密度和质量通量的影响,相同情况下,三角形波纹结构微细通道的总压降波动方差最大,是波动方差最小的普通光滑微细通道的1.37~1.45倍;质量通量的减小和热流密度的增大都会引起系统不稳定性增强;不同波纹结构微细通道导致压降波动方差不同的原因是波纹结构一方面增大对换热介质的加热面积,另一方面也增大了对换热介质的扰动。加热面积的增大增加了换热气泡的生成数量,波纹结构对换热介质的扰动加快了不同相的换热介质的能量传递速度。

In order to study the influence of the corrugated structure heat exchange wall on the flow boiling instability of micro channels,a micro channel flow boiling instability experimental platform is designed and installed.Three micro channels with different corrugated structure heat exchange walls are fabricated and processed.They are ordinary smooth,sine wave structure and triangle wave structure.A phase-change boiling heat transfer experiment on a heat transfer medium R141 b is performed.During the experiment,the effects of variables such as heat flux density and mass flux on the fluctuation of total pressure drop at the inlet and outlet during phase-change boiling heat transfer of micro channels with different corrugated structures are studied,as well as the change of the standard deviation of the total pressure drop of each micro channel.The research results show that the fluctuation of the total pressure drop at the inlet and outlet is mainly affected by the ripple structure of the heat exchange wall,the heat flux density and the mass flux.Under the same working conditions,the total pressure drop fluctuation of the triangular channel with the micro channel is the largest,which is 1.37~1.45 times that of ordinary smooth micro channel with the smallest fluctuation variance,and decrease of mass flux and increase of heat flux density will amplify system instability.