Based on study of sound propagation characteristics in periodic tube array, we investigate acoustic radiation characteristics in power station tube arrays. The heat exchanger structure in boiler is similar to phononic crystal. Different location in tube arrays acoustic radiation characteristics is studied. It shows that acoustic radiation directivity not only have relation with tube row number, but also have relation with frequency in acoustic band gap.

To study heat and mass transfer around pulverized coal particle under high intensity acoustic field with superposed steady component, two-dimensional, unsteady, laminar conservation equations for mass, momentum and energy transport in flue gas phase of power plant boiler were developed. Local Nusselt, space-averaged Nusselt and space- and time-averaged Nusselt numbers around coal particles, as functions of sound pressure level, frequency and ratio of acoustic velocity to steady slip velocity between particles and main flow, were discussed. There exists extremum frequency in which heat and mass transfer effect is the best in the range of audible sound frequency. It highlights a good application prospect in combustion for boiler.

To study flow field distribution characteristics around a pulverized coal particle in high intensity acoustic field with sonic frequencies, two-dimensional unsteady mass and momentum conservations for laminar flow in spherical coordinates were developed with actual parameters of power plant boiler. Displacement amplitude of incident sound wave is greater than characteristic length of particles, and acoustic Reynolds number is less than 20. Velocity field, axial pressure gradient, shear stress and flow separation angle around particle were analyzed at different acoustic Reynolds numbers and Strouhal numbers. It is found that axial pressure gradient, shear stress and separation angle are proportional to magnitude of sound at low frequency (~50Hz). However, they are different due to combined effects of curvature and flow acceleration at high frequency (~5 000 Hz). It provides theoretical foundation for further research on acoustic enhancement of heat and mass transfer in power plant boiler.