Study on Grey Correlation Degree of Influence Factors on ONB in Narrow Channel under Natural Circulation

Grey correlation degree calculation model which reflects the positive and negative relation of sequences is applied to calculate the relevant influence factors on ONB（Onset of Nucleate Boiling） in narrow channel under natural circulation.Results show that in the range of selected parameters: heating power shows a negative correlation with the distance between ONB and channel inlet,which proves that heating power promotes ONB occurrence;mass flow and pressure show positive correlation with the distance between ONB and channel inlet,which proves that these two factors postpone ONB occurrence.And a weak positive correlation exists between the narrow channel gap and inception heat flux at the location of ONB.The occurrence of ONB will be postponed as the value of channel gap becomes bigger.