A Study Of The Stiffness Analysis On Corrugated Tube And Its Effects On The Strength Of Tubesheet

Corrugated tube heat exchangers have been widely applied in industry recently due to their high heat transfer coefficient. However the tube-bundles of corrugated tube heat exchangers are different from those of common heat exchanger, and the stiffness of common straight tubes are higher than those of corresponding corrugated tubes,thus their supports to the tubesheet are different from each other. During the design process, corrugated tube is usually treated as straight tube with same size, and tubesheet strength is calculated by the method given in GB151-1999 (Tubular heat exchangers). Since the axial stiffness of corrugated tubes are much lower than those of corresponding straight tubes, so the calculation method mentioned above brought obvious uncertainty to the result. Actually, this problem has affected the development of the corrugated tube heat exchangers.In this dissertation, the FEM was applied to calculate the stiffness of the corrugated tubes used in heat exchangers. Then the effects of different parameters on the stiffness were analyzed, the corresponding stiffness curves were obtained and the engineering calculation method for calculating the stiffness of corrugated tube in heat exchanger was proposed. Through the equivalent stiffness calculation method, the geometry parameters of the equivalent straight tubes can be input into the design and calculation software of process equipment (SW6-1998) to calculate of the tubesheet strength. Finally, a set of engineering calculation methods for tubesheet strength in corrugated tube heat exchangers was well established.Currently there is no integrated technical method or code especially for calculating the stiffness of corrugated tubes. In this dissertation, a group of corrugated tube samples which are usually used in engineering are numerical simulated by FEM, and the stiffness data with different geometry parameters were collected after verification with experimental data. Further, the effects of different parameters on the stiffness were analyzed, and the calculation model for the stiffness of corrugated tube was proposed. After parameters correlation, the proposed model was proven to have good performance in forecasting the stiffness of corrugated tubes.