Investigation on the application of microtube and shell heat exchanger in energy conversion cycle

Print circuit heat exchanger (PCHE) is widely used in the present supercritical carbon dioxide (S-CO₂) Brayton cycle to support its superiority in compactness when compared with other energy conversion cycles. The maintenance and overhaul of PCHE are hard to be carried out when leakage and fouling appear because of the integral structure of the core. A microtube and shell heat exchanger (MSTE) is proposed in this research. The structure of the MSTE is similar to that of the conventional shell-and-tube heat exchanger except that the tube diameter is reduced to microchannel level. The cross-section area of the flow channel in MSTE takes more counts than that in PCHE, thus the volume and weight of MSTE can be reduced by more than 30% when compared with PCHE under typical design conditions of recuperator and precooler. Sensitivity analysis results show that if the designed recuperator and precooler with MSTE structure are adopted, the inlet temperature of compressor changes less than 1 ℃ when the hot or cold inlet temperature of recuperator increased by about 20 ℃. It can be concluded from the analysis results that the heat transfer capacity of MSTE is sufficient to adjust the general working condition fluctuations of the energy conversion cycle.