The effect of vibration on critical heat flux in a vertical round tube

Abstract

This paper deals with the results of experimental investigations on the effects of tube vibration on critical heat flux (CHF) in order to gain an understanding of the relationship between CHF and flow-induced vibration (FIV). The experiment was carried out in the following range of parameters: diameter (D)=0.008 m; heated length (L)=0.2, 0.4m; pressure (P)=101 kPa; mass flux (G)=403-2,551 kg/m(2). s; quality (x)=-0.045-0.289; amplitude (a)=0.0001-0.001 m; frequency (f)=0-70Hz. The CHF generally increases with vibration intensity, which is represented by vibrational Reynolds number (Re-v); the CHF enhancement is more dependent on amplitude than on frequency. CHF enhancement seems to come from the reinforced flow turbulent mixing effect by vibration in the vicinity of heat transfer surface. Based on the experimental results, an empirical correlation is proposed for the prediction of CHF enhancement by tube vibration. The correlation predicts the CHF enhancement ratio (En) with reasonable accuracy, with an average error rate of -2.18% and 27.75% for RMS.