Because of the harsh marine environment and limited space, the compact and high efficient heat exchanger is the best choice for FLNG heat exchanger, which can meet the demand for vaporization and liquefied devices in the field of marine engineering devices. To optimize the heat exchanger’s structural parameters and improve the performance, the factors mostly affecting the strength of the heat exchanger need to be determined, and static strength analysis and reliability analysis should be required. The strength of the different simplified heat exchanger core models is analyzed by using the Static Structural and the stress intensity distribution is obtained. The path between the high stress level cold channels has been set. The curves of the membrane stress, the sum of membrane stress and bending stress along the path have been obtained and the mesh-dependent numerical sensitivities are investigated. According to the operation conditions, the temperature boundary condition has been set and the mechanical stress and thermal stress are considered to evaluate the strength. The stress between the cold channels of heat exchanger core is relatively high, so the wall thickness between the cold channels is taken as one of random input variables in the subsequent reliability analysis. By choosing the thickness between the cold channels, cold channel pressure, hot channel pressure and elastic modulus as input random variables, the reliability analysis of heat exchanger has been done by using the Six Sigma Analysis of ANSYS Workbench, and next the cumulative distribution function curves of the membrane stress intensity, membrane plus bending stress intensity, response surface and the sensitivity are obtained. The effects of random variables on the reliability of heat exchangers are studied. The reliability analysis results have shown that the cold channel pressure loading is found to be the greatest factor to the structural strength and the second greatest factor is the thickness of the cold channels. The reliability of the heat exchange is more than 99.9% without considering thermal stress. When heat exchangers are being manufactured and under operation, the cold channel pressure loading and the thickness of the cold channels should be controlled strictly. These two random variables should be kept in minimum range to insure reliability. The results can be used as a reference for the reliability analysis of heat exchanger based on strength, which can guide the optimization design of heat exchanger structure. Moreover, the reliability analysis considering thermal stress can be further carried out.

 


Static Strength Reliability Analysis of the FLNG Compact and High Efficient Heat Exchanger

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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