Testing of a Compact Heat Exchanger for Use as the Cooler in a Supercritical CO_2 Brayton Cycle

摘要

The performance of a compact, printed circuit heat exchanger manufactured by Heatric has been tested for operating conditions corresponding to those of the cooler in the STAR-LM lead fast reactor (LFR) concept, which is designed with an indirect supercritical CO_2 Brayton cycle for power production. The heat exchanger was tested with water at atmospheric pressure on the cold side and supercritical CO_2 on the hot side. To match the planned cooler conditions, the hot side operated at a pressure of 7.5 MPa, inlet temperature in the range of 70-90°C, and an outlet temperature of 31.6-31.8°C, which is near the pseudocritical point. A test at 8.5 MPa and similar temperatures was performed for comparison. CO_2 mass flow rates were in the range of 100 to 700 kg/h, and heat loads between 10 and 30 kW. The heat transfer coefficients for Reynolds numbers between 2000 and 6000 are 200-800 W/m~2K. The accompanying water side heat transfer coefficient, measured in separate tests, was ～3500 W/m~2K and so the heat transfer rate for these cooler operating conditions was controlled by the CO_2 side. The average heat transfer coefficient was expected to increase with proximity of the outlet temperature to the pseudocritical temperature, but such an effect was not observed. Therefore the PCHE performance appeared to be unaffected by the substantial fluid property variations in the pseudocritical region.