Fig. 2: Flow boiling heat transfer performance of ALCHE.

a1 Heat flux curves with acoustics ON and OFF at 0.1 m s⁻¹ flow rate. a2 Heat flux curves with acoustics ON and OFF at 0.3 m s⁻¹ flow rate. b1 Heat transfer coefficient with acoustics ON and OFF at 0.1 m s⁻¹ flow rate. b2 Heat transfer coefficient with acoustics ON and OFF at 0.3 m s⁻¹ flow rate. c Pressure drop with acoustics ON and OFF under different flow rates. The error of the pressure drop is attributed to minor instabilities in the pump’s performance during liquid conveyance. d Bubble visualization images with acoustics ON and OFF (f_a = 1.5 kHz, P_a = 7.5 W, V = 0.1 m s⁻¹, q = 20 W cm⁻²). e Bubble size distribution with acoustics ON and OFF (f_a = 1.5 kHz, P_a = 7.5 W, V = 0.1 m s⁻¹, q = 20 W cm⁻²), the horizontal axis represents the logarithmic scaling of bubble area pixel number distribution (lg). The area of the bubbles is directly proportional to the number of pixels. f Bubble numbers with acoustics ON and OFF (f_a = 1.5 kHz, P_a = 7.5 W, V = 0.1 m s⁻¹, q = 20 W cm⁻²). g Schematic diagram of bubble images with acoustics ON and OFF at high heat flux (f_a = 1.5 kHz, P_a = 7.5 W, V = 0.1 m s⁻¹, q = 50 W cm⁻²). The blue circles in the figure represent the air bubbles, F_ar represents the acoustic radiation force on the bubbles. h Temperature decreases with acoustics ON at various heating powers (f_a = 1.5 kHz, P_a = 7.5 W). i Cyclic operation of the piezoelectric ceramic under different heat fluxes (f_a = 1.5 kHz, P_a = 7.5 W, V = 0.1 m s⁻¹). A total of 20 cyclic operations were performed, with each cycle consisting of a two-minute period: 1 min with acoustics OFF and 1 min with acoustics ON.