| The fouling of heat-exchange equipments is usual, which consists in the nature, daily life and different kinds of industrial production process, especially in the various diabatic processes. The carbon deposit, as one of fouling, exists for the heat-exchange equipments, and severely influences the safe economic operation of heat-exchange equipments. Therefore, it is necessary to deeply research the chemical components and forming mechanics of carbon deposit for dealing with the actual problems due to the carbon deposit and suppressing the formation of carbon deposit to enhance the heat transfer.Firstly, in this thesis, based on the analysis on the components and property of carbon deposit during the heat-exchange process, as well as considering the previous research on the fouling, the prediction model was put forward, the evaluating indicators regarding the effect of carbon deposit to the heat-exchange performance of heat exchanger was deduced. In addition, the relation between the carbon deposit and heat-exchange performance was discussed at length and shown as follows.(1) The criterion which is defined as the ratio of heat transfer effectiveness before and after carbon deposit, (?), was put forward on the basis of the mechanism of heat transfer in heat exchangers. The surface temperature of exchangers has strong influence on it. With the increase of surface temperature, the quantity of carbon deposit on the heat-transfer surface increases. Hence, controlling the surface temperature should be taken into consideration for the design, operation and cleaning of exchangers.(2) As far as the different kinds of exchangers concerned, when the other parameters are uniform, the heat-transfer performance of reverse-flow heat exchangers influences the formation of carbon deposit most, followed by that of the cross-flow ones, which exerts less impact on the formation of carbon deposit, while the performance of the parallel-flow ones has the least influence among these types... |
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