Study on thermal deformation of hybrid printed circuit heat exchanger for advanced nuclear reactor

The intermediate heat exchanger (IHX) is one of the key components in advanced nuclear reactor power generation system. Printed circuit heat exchanger (PCHE) with mini-channels is a good candidate for the IHX. But the whole PCHE with tens of thousands of mini-channels is hard to be modeled and calculated at high temperature. Thus, the homogenization method, which can calculate the thermal deformation of the whole hybrid mini-channel PCHE, is conducted in this study and both the elastic and elastic-plastic finite element analysis methods are used. Here, the performance of the PCHE is assumed to be isotropic in the simulation. The results show that the macroscopic thermal deformation of the whole PCHE follows a gradually downward trend from hot side to cold side, while obvious thermal stress concentration is observed around the junctions between the PCHE core and cover plate. The stress and strain calculated by elastic and elastic-plastic methods under different constraints show quite different patterns. For the thermal deformation analysis of PCHE under weak constraint or small temperature difference conditions, the stress and strain results by elastic analysis and elastic-plastic analysis are similar so that the elastic analysis can be used. Under the strong condition, the stress of PCHE calculated by elastic analysis is much higher than that of elastic-plastic analysis, while the strain is lower than that of elastic-plastic analysis. The relative deviations of stress are 100.883% and 120.786% along path 1 and path 2 respectively. And the relative deviations of strain are 6.987% and 10.139% along path 1 and path 2 respectively. The elastic-plastic analysis should be used instead of the elastic analysis.