微细通道CO_2流动沸腾换热临界热流密度研究

CO2在微细通道内流动沸腾换热过程所具有的临界热流密度(CHF)对于其换热系数有着重要影响。根据国内外现有发表的公开文献的实验数据分析了质量流量、饱和温度、管径等对临界热流密度的影响,并对理论模型与试验数据进行误差分析。发现Bowring预测关联式对小于3 mm管径内临界热流密度预测精度较高,在30%误差范围内可以达到70%预测精度,Wojtan预测关联式具有较小的平均绝对误差。提出了今后CO2在微细通道内沸腾换热CHF的研究方向。

Study of the Critical Heat Flux Density of Boiling Heat Exchange During the Flow of CO2 in Microchannels

The critical heat flux(CHF) density during the flow of CO2 in microchannels in the process of boiling heat exchange has an important influence on the heat exchange coefficient.On the basis of the test data in the literatures currently published in domestics,the authors have conducted an analysis of the influence of the mass flow rate,saturated temperature and tube diameter etc.on the critical heat flux density and performed an error analysis between the data obtained by using the theoretical model and the test ones.It has been found that the Bowring prediction correlation formula has a relatively high precision in predicting the inner critical heat flux density of tubes with a diameter of less than 3 mm.Within an error range of 30%,the prediction precision can reach 70%.However,Wojtan prediction correlation foumula has a relautively small mean absolute error.The direction of the future study in the boiling heat exchange by CO2 flowing inside microchannels has been put forward by the authors.