The influence of operation parameters on stress of plate-fin structures in LNG heat exchanger

• A finite element model was proposed to simulate the stress of plate-fin structures.
• This paper obtained the area of the crack failure in plate-fin structures.
• The mismatching thermal expansion coefficient is main reason of the crack failure.
• Some measures were proposed to relieve the crack failure.

In order to ensure the structural safety of plate-fin structures, a model was proposed to simulate the stress of plate-fin structures in actual operation process of LNG heat exchanger based on Finite Element Method and thermal elastic theory. The influence of operation parameters were investigated on stress of plate-fin structures. The results show that the stress reaches the peak value in brazed joint near the fin side, and a crack would initiate in this region. This is consistent with the experiment result based on pressure burst of partial model of PFHE. The peak value of equivalent stress increases steadily with the increase of the temperature difference between natural gas (NG) and mixture refrigerant (MR) and is slightly impacted by the temperature gradient along the flow direction of NG. Additionally, the peak value of equivalent stress increases with the increase of NG or MR pressure and the influence of NG pressure is more remarkable. These results will provide some constructive instructions in the design and safe operation for plate-fin heat exchanger in a large-scale LNG cold-box.