Energy conversion apparatus

An engine body, comprising:

• a piston body comprising a piston chamber;
• a regenerator body comprising a regenerator conduit;
• and
• a heater body comprising a plurality of heating fluid pathways and a plurality of working-fluid pathways, the plurality of heating fluid pathways having a heat transfer relationship with the plurality of working-fluid pathways, the plurality of working-fluid pathways fluidly communicating between the piston chamber and the regenerator conduit, the heater body also having a combustor body defining a combustion chamber;
• wherein the engine body comprises a monolithic body defined at least in part by the piston body, the regenerator body, and the heater body, and wherein at least a portion of the heater body that defines the monolithic body is arranged so as to circumferentially surround the combustion chamber.

An engine assembly, comprising:

• a plurality of engine bodies, wherein respective ones of the plurality of engine bodies respectively define a first monolithic body, the first monolithic body comprising:
• a piston body comprising a piston chamber,
• a regenerator body comprising a regenerator conduit, and
• a working-fluid heat exchanger body comprising a plurality of working-fluid pathways fluidly communicating between the piston chamber and the regenerator conduit;
• and
• a heater body defining a second monolithic body comprising a plurality of heating fluid pathways, the heater body includes a combustor body having a combustion chamber body and a conditioning conduit body, the combustor body defines a combustion chamber and the conditioning conduit body circumferentially surrounds the combustion chamber, a conditioning conduit is defined between the combustor body and the conditioning conduit body, the conditioning conduit fluidly communicates with the combustion chamber at a distal portion of the combustion chamber;
• wherein the plurality of engine bodies are coupled to the heater body, and wherein the plurality of heating fluid pathways have a heat transfer relationship with at least some of the plurality of working fluid pathways.