Strength Analysis Of The Hydrogen Recovery Condenser And Research Of Boiling Heat Transfer

As energy transfer equipment, heat exchangers are widely used in oil refining, chemical, nuclear, pharmaceutical, light industry and other industrial fields. With the development of industry, heat exchangers tend to be large in size and high in operation parameters. The existing conventional design standards can not meet some specific demands for the design of large heat exchangers. In this thesis, strength analysis for a large hydrogen recovery condenser with oblique conical shell was carried out using design by analysis method with the software of ANSYS. In addition, as boiling process at the shell side of this heat exchanger exists, which is much complicated than the heat transfer between single phases, boiling heat transfer was simulated using the CFD software Fluent. The main contributions are as follows.(1) The finite element model was established using shell and solid elements of ANSYS. MPC was used to connect the two kinds of elements. Tow models, namely solid model and shell-solid model, of a heat exchanger, were used to verify the accuracy of MPC. Results show that MPC method is effective in the finite element analysis for the whole structure of a heat exchanger. (2) Stress intensity under seven dangerous cases of driving, parking, normal operating and hydrostatic tests, were analysed. Results show that stress intensity of tube sheets under the mechanical loads is small. The main stress intensity is caused by thermal stress. For the cylinder, the main stress intensity is generated by the mechanical loads. The influence of thermal stress is very small, which is mainly on the connections of cylinder and tube sheets.(3) Mechanism of boiling process is summarized including empirical and semi-empirical formulas of the bubble parameters and calculation models of two-phase flow caused by boiling. Boiling heat transfer of the fluid around a single tube in shell-side was simulated using the Wall Boiling Model of Euler Model in Fluent. The vapor volume fraction along the axial direction was analyzed as well as the changing of heat transfer coefficient with different heat flux, different inlet velocity and inlet temperature. Results show that the vapor volume fraction increases gradually along the axial direction and increases with the increase in the heat flux and the inlet temperature, decreases with the increase in the inlet velocity. Meanwhile it is found that increasing the heat flux, inlet velocity and inlet temperature is conducive to improve the heat transfer coefficient.