The effect of key parameter changes on the critical heat flux of spray evaporatively-cooled vibrating surfaces using a single misting nozzle

Abstract

• • New CHF model shows parameter change influence for cooling of vibrating surfaces. • • Model is constructed using the Generalized Buckingham Π-Theorem. • • Measured data obtained from an electrically-heated test-piece excited by a shaker. • • Surface-to-nozzle distance in presence of vibration significantly influences CHF. A new correlation model is examined for capturing the combined influences of surface-to-nozzle distance and coolant flow rate on critical heat flux associated with spray evaporative cooling of vibrating surfaces. The correlation model is constructed using dimensional analysis by applying the Generalized Buckingham Π-Theorem. The model is calibrated using experimentally-measured spray evaporative cooling data, taken from an electrically-heated horizontal flat circular test-piece excited by a shaker through a range of low and high frequencies of vibration, from small to large amplitude. To understand the combined effect of frequency, amplitude, and surface-to-nozzle distance, at critical heat flux, Vibrational Reynolds Number, Acceleration Number, and Dimensionless Surface-to-Nozzle Distance are used. The results show that surface-to-nozzle distance, in the presence of dynamic effects, significantly influences the critical heat flux, whereas vibration amplitudes and frequencies have differing effects in response to variations in both surface-to-nozzle distance and flow rate. Surface-to-nozzle distance can either increase or decrease the heat transfer, depending on the vibration range. The calibrated correlation model is capable of predicting the effect of surface-to-nozzle distance on the critical heat flux with errors in the range −4.8% and + 10.5%.