Experiment on the antiscale and descaling and heat transfer enhancement of acoustic cavitation sewage heat exchanger

The scaling of sewage heat exchanger in sewage source heat pump system leads to increase of thermal resistance and decrease of heat transfer effect. In order to solve these problems, the acoustic cavitation technology was introduced into sewage heat exchanger. The dynamic experiment table of antiscale & descaling and heat transfer enhancement by acoustic cavitation sewage heat exchanger was established. Mathematical models of acoustic cavitation antiscale & descaling and heat transfer enhancement were analyzed. The fouling growth characteristics, and the law of antiscale & descaling and heat transfer enhancement effect of sewage heat exchanger tubes under different influence parameters were researched. The results are as follows. The amount of scale, scaling rate, fouling rate and fouling thickness of heat exchanger tubes are increased with the decrease of sewage flow velocity. The largest amount of scaling is 106 g, fouling thickness is 0.54 mm, and fouling rate is 12.6 kg/(m² · h). Descaling rate increased with the increase of flow velocity and acoustic cavitation action time, and the largest descaling rate is 85.7%. Sewage viscosity has a huge impact on the various indexes and has greater influence with the smaller velocity. Heat transfer coefficient and its enhanced percentage are increased with the increase of acoustic cavitation action time, temperature of sewage and fouling moisture rate, and in addition, the percentage of heat transfer coefficient runs up to 53.4%. So the antiscale & descaling and heat transfer enhancement of acoustic cavitation sewage heat exchanger have a certain feasibility and high efficiency, and great significance to energy conservation and emissions reduction.