Abstract：Generally, the heat transfer are achieved by three ways of conduction, convection or radiation. Clearly, enhanced heat transfer technology, research and development have increased from three kinds of heat transfer process to proceed, which involves the most extensive and most studied is the convective heat transfer enhancement. This article discusses the enhanced heat transfer for the following questions.
Heating surface can be significantly extended by finned tube, reducing the layout of space and weight of the boiler heat transfer surface, it now has been widely used on the boiler economizer section. Practice has proved that it is important in improving boiler safety and economy. Spiral Tube economizer has been designed and calculated in this paper； Because the heat transfer coefficients of traditional fluorescent tubes economizer between flue gas side and water side are significant differences （water side heat transfer coefficient is more 1-2 orders of magnitude than the gas side heat transfer coefficient）, we can see that the effect of gas - liquid mass heating transfer depends on the heat transfer coefficient of flue gas side, in order to reduce the occupied space, manufacturers tend to increase the speed to improve the convective heat transfer coefficient of the flue gas side, resulting in the increased wear and tear of economizer operation and reducing the life of the unit. This Paper discusses the problem of wear economizer； the working conditions of super-heater and economizer are different, thus it was limited in application of the finned tubes in super-heater. For boiler of media pressure and waste heat boiler with similar working conditions, the paper discussed the terms of using finned tubes in super-heaters and what should pay attention； When it is need to strengthen a heat transfer process, which should first determine is the thermal resistance of heat transfer of which part is large and it is the most effective measure to for strengthen significantly in this resistance of the heat transfer. The paper discusses heat transfer problems in theory； the air pre-heater of boiler, generally has the phenomenon of low temperature corrosion and blocked ash, which resulting in increased air leakage and lack of fan output. Heat pipe air pre-heater can solve the problem of low temperature corrosion. The paper discusses the characteristics of the heat pipe air pre-heater tube compared to the conventional rotary air pre-heater.
Keywords: heat transfer enhancement, boiler, convection heating surface, fin...