The big issue of S-CO2 Brayton cycle is to develop compact heat exchanger which is comparable to the size of turbines and compressors. One of the candidates of this compact heat exchanger is printed circuit heat exchanger (PCHE). PCHE is manufactured by chemical etching and diffusion bonding technologies (Fig. 14). Using these two technologies, PCHE has many micro-scale channels and durability to high pressure and temperature. Further, it has larger heat transfer area per volume than other conventional heat exchanger. However, its performance is greatly affected by the channel shapes. Thus, it is important to develop efficient and processible channel shape of PCHE. Recently, diverse heat exchangers also can be suggested and studied for the purpose of S-CO2 Brayton cycle as well as the PCHE.