Numerical investigation to optimize the inlet flow distributor of the intermediate heat exchanger in an HTGR

Abstract

The intermediate heat exchanger (IHX) is a key part of the high-temperature gas-cooled reactor (HTGR). The inlet flow uniformity then strongly impacts the heat transfer in the IHX. The inlet passage design is the main cause of flow nonuniformities and an inlet flow distributor has been shown to effectively reduce these nonuniformities. This study numerically optimized the flow distributor structure by improving the flow uniformity. The structural optimization varied the installation height, distributor length and distributor area. The results show that the distributor length has an optimal value and the distributor area has two opposing effects on the velocity uniformity with both coupled to the installation height. The flow field analysis indicates that the ratio of the flow directly into the distributor and that guided into the distributor that had opposing transverse velocities is the key factor determining the velocity uniformity and the optimization effect can be intuitively reflected by the magnitude of the swirling strength. The optimization shows that the narrow structure at the 350 mm installation height gives the best velocity uniformity of 0.974.