“…The simulation results suggested that regenerative materials with high porosity placed in the warm end of regenerator can reduce the pressure drop. In 2019, Panda et al [ 16 ] introduced the experimental empirical correlation to represent the fluid flow and heat exchange characteristics in the regenerator based on Xu's work [ 12 ]. The author further studied the shape of orifice and waiting time in rotary valve, which indicated that smaller waiting time and Gaussian-shaped port can acquire more PV work in the expansion chamber, so as to obtain higher cooling power.…”