| The analysis and research of fluid flow and heat transfer in heat exchangers are helpful in the development of safe, high efficiency and economical heat exchanger structure. In conventional research of heat exchangers, experimental method is mostly employed. However, it cannot keep pace with the requirement of research and development of heat exchangers because of its intrinsic disadvantages such as high experimental expense, long period, strict limit, complication in model transition, incapacity of getting detailed information, etc. Currently, with the advancement of computational fluid dynamics, computational heat transfer and computer technology, it is possible to use numerical simulation method to analyze and study heat exchangers. As numerical simulation method is used more widely, more and more people are getting to think that numerical analysis is a feasible approach to save investment and decrease waste and employ it in scientific research.It is an important topic to carry out further study on high efficiency energy-saving heat exchangers with longitudinal flow of shellside fluid(HELFSF). Based on the research of gross structure of HELFSF equipments, our research center optimizes it and develops a new structure which is the combination of rod-ring(rod grid, ring) support, tapered flow distributor and jacket-jacketed rod-baffle heat exchanger with tapered flow distributor(Patent Number: ZL91219300X). It is demonstrated in industrial practice that the new type HELFSF has higher heat transfer efficiency with comprehensive parameter a / A p 50% up and lighter weight 20%-40% down. At present, the new type HELFSF has been used widely in industrial production and brought distinct economic and social efficiency.The setup of flow distributor is a new structure developed to enhance the heat transfer efficiency of shell-and-tube heat exchangers and improve shellside structure. By installing flow distributor, not only the direct impact of high speed fluid on tube bundle at inlet can be prevented but also the distribution of shellside fluid can be improved. As a result, the heat transfer area of tube bundle near inlet can be used fully and the possible flow-induced vibration near inlet can be prevented. Due to the complexity of conventional flow distributor, our research center has developed the jacketed tapered flow distributor, which simplifies greatly the conventional structure of flow distributor. Since tapered structure is used in the flow distributor, the inlet has a sloping section which overcomes the shortcoming of conventional flow distributor that the fluid resistance of media entering shellside is different and makes fluid enter the shell more uniformly. Presently, there is no standard to comply with for the parameters of the new structure such as the length of high and low end of the flow distributor, etc. However, it is certain that the high end of the flow distributor must cover the inlet. Because such flow distributor is used increasingly widely in industry, it has become the emphasis of research on flow distributor to make certain the structural parameters and optimize the structure.In the paper, the numerical simulation method is employed to compute, analyzeand compare the fluid flow condition in the new type flow distributor setup of HELFSF-tapered flow distributor. Further optimal design is carried out according to the flow condition of fluid in the flow distributor.The main work and innovative points in the paper are as follows:1. In the paper, three-dimensional numerical simulation of fluid flow in the tapered flow distributor of new type HELFSF is accomplished for the first time, which is not found in previous work by others.2. In the paper, large universal commercial CFD software-FLUENT is employed to study the characteristics of fluid flow in the flow distributor of new type HELFSF and detailed information of fluid flow is obtained, which cannot be obtained by using experimental method.3. In the paper, the effect of the alteration of structural parameters in the tapered... |
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