Research On Characteristic Of Flow And Heat Transfer And Development Of Fouling Of City Sewage

With the serious issues about energy and environment increasingly,"saving energy and reducing emission"has become the one of important policy of many countries of world. And the city untreared sewage is an excellent renewable low potential energy because it is moderate temperature, large quantity and widespread distribution. But the application and popularization of city sewage cooling and heating source are limited because of the puzzle of bad quality of water, complex component and fouling of city sewage. How to calculate and analyse the characteristic of flow, heat transfer and fouling has been bottleneck of application and popularization of city sewage cooling and heating source. And it is not enough to application for present researches. Aiming at the requirements of engineering, the characteristics of flow, heat transfer, biofouling of sewage, the application of nanometer taitanium polimer covering material by theoretical derivation and field engineering experiments. These will supply base ground for the application and popularization of city sewage cooling and heating source.The characteristics of flow and heat transfer of sewage are the bases of application of city sewage cooling and heating source. In this paper the rheology of sewage is tested and measured and the constitutive equations of rheology is reached by experiments. And the velocity field and temperature field of sewage in circle pipe are analysed. In addition to, the equation of coefficient of drag of flow and heat transfer rule equation of sewage in circle pipe under turbulence are developed by calculated. The differences of coefficient of drag of flow and convection heat transfer between sewage and clean water are analyzed.How to analysis and overcome the impact of heat exchanger fouling is a key problem of application of sewage. The component of fouling is analysed in this paper. It is found that the foulings impact heat exchangers are organic foulings mainly. And the models of development of fouling formation are study. The impacts of velocity of sewage to biofouling deposit are explored base on the characteristic of stress and deposit model in every stage. The thermal resistance models of fouling of six common heat transfer pipes used is reached. They are asymptotic function of time. And the press loss model of fouling of heat exchanger is developed through calculation and experiments.The application of nanometer taitanium polimer covering material is new technology of anti-fouling of sewage heat exchanger. The proper nanometer covering material is chosen base on the characteristics of fouling. And the characteristics of flow, heat transfer and fouling of sewage in nanometer coat pipes are study. By contrast with other pipe material that can be known the proper nanometer coat is an availability anti-fouling method.In a word, the researches and analysis of characteristics of city sewage and fouling support supply to engineering application, management of system and further study of sewage cooling and heating source.