Multi-tiered regenerator

A thermally communicating regenerator for adjusting temperature of gas or fluid flowing therethrough in at least one of a unidirectional or bi-directional manner, comprising:

• a housing having a first side configured to cool a working gas or fluid and a second side to heat a working gas or fluid as the working gas or fluid is directed in a vertical direction, the second side being opposite that of the first side;
• a first plurality of thermal portions stacked vertically on the first side extending from a bottom of the housing to a top of the housing;
• and
• a second plurality of thermal portions stacked vertically on the second side extending from the bottom of the housing to the top of the housing;
• wherein at least one of a first thermal portion in the first plurality of thermal portions or a second thermal portion in the second plurality of thermal portions is formed of conductive porous material, wherein the first thermal portion is thermally coupled to the second thermal portion via a first set of thermal coupling members that transfer heat from the first thermal portion to the second thermal portion.