Stress characteristics of plate-fin structures in the cool-down process of LNG heat exchanger

In order to ensure the structural safety of plate-fin structures, a model is proposed to simulate the stress characteristics of plate-fin structures in the cool-down process of LNG heat exchanger based on Finite Element Method and thermal elastic theory. The simulation results show that the equivalent stress rapidly changes and consistently reaches the peak value in the brazed joint, and a crack initiates in this region in the cool-down process. The peak value of equivalent stress in plate-fin structures steadily increases with the increase of temperature difference between natural gas (NG) and mixture refrigerant (MR) and it is slightly impacted by the temperature drop rate as the temperature drop rate of NG is the same as that of MR in the cool-down process. The simulation results are consistent with the experiment results. These results will provide some constructive instructions in safe operation and improvement of the cool-down process for plate-fin heat exchanger in a large-scale LNG cold-box.