A review of regenerative heat exchange methods for various cooling technologies

Regenerative heat exchange method internally recovers useful cooling and heating energy inside a closed-loop cooling system. However, depending on the specific cooling mechanisms for various cooling technologies, the configurations and characteristics of regeneration methods diverge significantly. Therefore, it is necessary to review the fundamental principles and clarify the common features and major differences of the regeneration methods for various typical cooling technologies. This study classified regeneration methods into three categories: recuperative type for steady state operated systems, regenerative type for systems under cyclic operation, and heat recovery type for systems with solid-state functional materials. The first group of regeneration methods are recuperative heat exchangers, transferring heat continuously between two streams of fluid with different inlet temperatures to pre-cool one stream and enhance the cooling power, such as the suction-line heat exchanger for vapor compression systems. The second group of regeneration methods are regenerative heat exchangers, which fundamentally are energy storage devices to cyclically transfer heat from gaseous refrigerant flowing through them. The third group of regeneration methods are internal heat recovery processes, wherein fluid is applied as a regenerator to store/release thermal energy cyclically to pre-cool and pre-heat the solid-state functional materials. For each of the three regeneration methods, their physical principles, a summary of their state-of-the-art development status, and assessments of their advantages, limitations and unique features are presented.