关键词: 污水, 热泵, 换热器, 流态化, 防垢

Abstract: Using sewage source heat pump to heat and ventilate for building is an effective way of energy saving and emission reduction. However,fouling of heat exchanger remains an urgent and unresolved issue. In order to solve this problem,the solid-liquid fouling fluidized-removing technology was applied for fouling prevention and removing of sewage heat exchanger. A set of fouling removing system using sand as fouling removing particles was established in this paper. Combined theory analysis with experimental validation,the optimal flow rate,the heat transfer enhancement effect,the optimal technological parameters of anti-attrition and the fouling removing ability of fouling fluidized-removing were discussed. The experimental results showed that the sand grains with the diameter of 2—3mm could be fluidized if the flow rate of the sewage reached 0.87m/s.The recycling efficiency of the sand grains was almost 95%. The on-line cleaning was realized. The fouling fluidized-removing technology could effectively remove soft dirt and rust of sewage heat exchanger. The heat transfer coefficient increased by 25.6% after the fouling removing system continued to run 24 hours. In order to induce attrition and assure the fouling removing efficiency,the optimum parameters were set as follow:Volume fraction of sand was 4% and the flow rate was stirring-up velocity.

Key words: sewage, heat pump, heat exchanger, fluidization, fouling prevention