Fig. 1. Schematic diagram of the CLEAR-I structure 1. Reactor core, 2. Central measuring column, 3. Heat exchanger, 4. Air cooler, 5. Safety container

Fig. 2. Heat exchanger composition structure diagram 1. Center downcormer, 2. Double layer heat exchange tube, 3. Shell of heat exchanger, 4. Pressure chamber, 5. Upper tube sheet, 6. Lower tube sheet, 7. Secondary side inlet, 8. Secondary side outlet, 9. Liquid metal inlet window, 10. Liquid metal outlet window, 11. Discharge chamber, 12. Flow distribution device, 13. Secondary side coolant mixing device, 14. Heat shielded housing

Fig. 3. Coolant flow direction diagram

Fig. 4. Variation of the number of heat exchanger tubes with the tube length

Fig. 5. Variation of total heat transfer coefficient with the tube length

Fig. 6. Effect of heat exchanger tube length the on shell-side (a) and tube-side (b) pressure drop

Fig. 7. Effect of heat exchanger tube length on the JF factor

Fig. 8. Variation of total heat transfer coefficient with the outer diameter

Fig. 9. Effect of the outer diameter of heat exchanger tube on shell-side pressure drop (a) and tube-side pressure drop (b)

Fig. 10. Effect of outer diameter of heat exchanger tube on the JF factor

Fig. 11. Variation of total heat transfer coefficient with wall thickness

Fig. 12. Effect of heat exchanger tube wall thickness on tube-side pressure drop

Fig. 13. Effect of heat exchanger tube wall thickness on the JF factor

Fig. 14. Effect of heat exchanger tube spacing on the shell-side pressure drop

Fig. 15. Effect of heat exchanger tube spacing on the JF factor

Fig. 16. Contribution ratio of each parameter

Fig. 17. Variation curve of JF factor (a) and CER (b) factor with number of iterations

Table 1. Main thermal-hydraulic parameters of the primary heat exchanger

Table 2. Preliminary design parameters of the main heat exchanger

Table 3. Design parameter range of the heat exchanger tube

Table 4. Comparison of heat exchanger performance before and after optimization