Research On Fouling Growth Characteristic In Heat Exchanger Of Sewage Source Heat Pump System

Fouling is found all over the heat transfer processes of the heat exchange equipments which usese the liquid as the medium, in the system of HVAC especially in the system of seawage source heat pump a lot of problems can decreased the heat transfer efficiency, such as the severe water pollution, the pipe wall corrosion, the muddy-water deposition, the microorganism propogation, the crystallization fouling and so on. The economic loss caused by fouling is as high as 0.25%~0.38% of Gross National Product.The shell and tube heat exchanger are more widely used in lots of systems of seawage source heat pump than other format heat exchange equipments because of its low cost of production, wild material selection, reliable working station and adaptation to high temperature and high pressure environment.Therefore, It is significant and necessary to do the research on the growth of fouling in the shell and tube heat exchanger.Firstly, the familiar types, cause and harm of fouling in the shell and tube heat exchanger are systematically summarized.The fouling mechanism and its influential factors are introduced.The thermal resistance prediction model of fouling and pressure drop prediction model of fouling is founded.Then,the monitor method of fouling thermal resistance and fouling pressure drop monitoring the growth of fouling using the back-flush is established stably and reliably.The particulate fouling such as mud is the main research object.On one hand,the growth condition of the fouling in the tube is monitored though the experimental system of fouling thermal resistance.Then the pressure drop prediction model of fouling is founded and it is demonstrated by the experimental data of pressure drop.On the other hand,by the experiment I found the relation between steady thickness of the fouling and velocity of flow, in the same time I do a feasible experiment in flat heat exchanger.Finally, in the article I combine the research on the growth of fouling and reckon of the shell and tube heat exchanger, and advance a fouling coefficient for reckoning of the shell and tube heat exchanger.