<p>In one embodiment, the invention relates to a heat exchanger suitable for use with a thermodynamic cycle-based machine such as an engine, an energy conversion machine, a cooling machine or other suitable systems and machines. The heat exchanger can include one or more tubes arranged to form a heat exchanger. In one embodiment, a unitary tube is used. The heat exchanger can include a canister that includes a regenerator material. The canister can be in thermal communication with a working material and a containment vessel having a containment chamber in one embodiment.</p>
