A heat flow was measured in the absence of and in the presence of acoustic streaming. The streaming produced by ultrasonic transducers was visualized by a particle imaging velocimetry (PIV) and an infrared thermal camera. The experimental results revealed that acoustic streaming could accelerate the melting process as much as 2.5 times, compared to the rate of natural melting (i.e., the melting without acoustic streaming). In addition, temperature and Nusselt numbers over time provided conclusive evidence of the important role of acoustic streaming on the melting phenomena of the phase change material (PCM).