Hydraulic Design Optimization of Flow Distribution Device in Bottom Header of IHX for SFR

An intermediate heat exchanger (IHX) of a sodium-cooled fast reactor is a typical shell and tube-type counterflow heat exchanger. Primary sodium flows on the shell side, and secondary sodium flows on the tube side. There is a central downcomer and 25 rows of tubes. Tube rows in the periphery of the IHX see primary sodium at high temperatures compared to the inner rows of a tube. Non-uniform heat exchange increases the temperature difference between sodium from different rows, thereby increasing thermal damage to the tube sheet. A flow distribution device in the bottom header would regulate higher flow in the outer rows, whose design is optimized using a 3D CFD hydraulic analysis. The effect of the conical diffuser and vertical baffle on the flow distribution inside the bottom header is quantified. A vertical baffle of 225 mm in height (located 12 mm below the tube sheet) provided after the 18th row rendered a flow distribution very close to the desired one. The deviation between expected and estimated flow reduces to ~10%.