Monolithic heat-exchanger bodies
A monolithic heat exchanger body includes a plurality of heating walls and a plurality of combustion fins. The plurality of heating walls are configured and arranged in an array of spirals or spiral arcs relative to a longitudinal axis. Adjacent portions of the plurality of heating walls respectively define a corresponding plurality of heating fluid pathways therebetween. The plurality of combustion fins are circumferentially spaced about a perimeter of an inlet plenum. The inlet plenum includes or fluidly communicates with a combustion chamber. The plurality of heating fluid pathways fluidly communicate with the inlet plenum. The plurality of combustion fins occupy a radially or concentrically inward portion of the monolithic heat exchanger body. The plurality of heating fluid pathways have a heat transfer relationship with a heat sink disposed about a radially or concentrically outward portion of the monolithic heat exchanger body. A plurality of conduction breaks disposed radially or concentrically outward relative to the plurality of combustion fins at least partially inhibit heat conduction from the plurality of combustion fins to the plurality of heating walls.
1. A monolithic heat exchanger body, comprising:
a plurality of heating walls configured and arranged in an array of spirals or spiral arcs relative to a longitudinal axis, wherein adjacent portions of the plurality of heating walls respectively define a corresponding plurality of heating fluid pathways therebetween; and
a plurality of combustion fins circumferentially spaced about a perimeter of an inlet plenum, wherein the inlet plenum comprises or fluidly communicates with a combustion chamber and the plurality of heating fluid pathways fluidly communicate with the inlet plenum;
wherein the plurality of combustion fins occupy a radially or concentrically inward portion of the monolithic heat exchanger body, and wherein the plurality of heating fluid pathways have a heat transfer relationship with a heat sink disposed about a radially or concentrically outward portion of the monolithic heat exchanger body; and
wherein a plurality of conduction breaks disposed radially or concentrically outward relative to the plurality of combustion fins at least partially inhibit heat conduction from the plurality of combustion fins to the plurality of heating walls.
2. The monolithic heat exchanger body of claim 1 , wherein at least a portion of the plurality of conduction breaks are defined by respective downstream portions of the plurality of combustion fins being configured and arranged in spatial separation from corresponding upstream portions of the plurality of heating walls.
3. The monolithic heat exchanger body of claim 1 , wherein the plurality of conduction breaks respectively comprise a gap or space between a combustion fin and corresponding heating wall.
4. The monolithic heat exchanger body of claim 1 , wherein the plurality of conduction breaks respectively comprise a difference in a material property, a material composition, and/or a material structure, relative to the plurality of combustion fins and/or the plurality of heating walls.
5. The monolithic heat exchanger body of claim 1 , wherein the plurality of conduction breaks comprise one or more of: a mesh structure, a three-dimensional lattice structure, or a porous medium structure.
6. The monolithic heat exchanger body of claim 1 , wherein the plurality of conduction breaks comprise respective regions of the heating walls having unsintered or partially sintered powder material resulting from an additive manufacturing process used to form the monolithic heat exchanger body.
7. The monolithic heat exchanger body of claim 1 , wherein the plurality of combustion fins are configured and arranged in an array of spirals or spiral arcs relative to the longitudinal axis.
8. The monolithic heat exchanger body of claim 1 , wherein the plurality of combustion fins are monolithically integrated with corresponding ones of the plurality of heating walls.
9. The monolithic heat exchanger body of claim 1 , wherein the heat sink comprises a plurality of working-fluid bodies, the plurality of working-fluid bodies comprising a plurality of working-fluid pathways that have a heat transfer relationship with the plurality of heating fluid pathways.
10. The monolithic heat exchanger body of claim 1 , wherein the heat sink comprises a plurality of heat transfer regions circumferentially spaced about the monolithic heat exchanger body.
11. The monolithic heat exchanger body of claim 10 , comprising from 2 to 8 heat transfer regions circumferentially spaced about the monolithic heat exchanger body.
12. The monolithic heat exchanger body of claim 11 , wherein the plurality of heating fluid pathways are configured and arranged to pass adjacent to at least some of the plurality of heat transfer regions in a circumferential series, the circumferential series of a respective one of the plurality of heating fluid pathways having a sequence depending at least in part on a circumferential location at which the respective one of the plurality of heating fluid pathways fluidly communicated with the inlet plenum.
13. The monolithic heat exchanger body of claim 12 , comprising:
a first heating fluid pathway passing adjacent to at least some of the plurality of heat transfer regions in a first circumferential series, the first circumferential series beginning with a first heat transfer region, and followed by a second heat transfer region, and followed by a third heat transfer region; and
a second heating fluid pathway passing adjacent to at least some of the plurality of heat transfer regions in a second circumferential series, the second circumferential series beginning with the second heat transfer region, and followed by the third heat transfer region, and followed by a fourth heat transfer region.
14. The monolithic heat exchanger body of claim 10 , wherein the plurality of heat transfer regions occupy a region of the monolithic heat exchanger body disposed radially or concentrically outward from the plurality of conduction breaks.
15. The monolithic heat exchanger body of claim 14 , wherein the plurality of heat transfer regions respectively comprise an array of working-fluid pathways that have a heat transfer relationship with the plurality of heating fluid pathways.
16. The monolithic heat exchanger body of claim 15 , wherein at least a portion of the working-fluid pathways are monolithically defined within respective ones of the plurality of heating walls.
17. The monolithic heat exchanger body of claim 1 , wherein:
the combustion fins are configured and arranged to operate at a sufficiently high temperature for stable combustion within the portion of the heating fluid pathways disposed upstream from the conduction breaks.
18. The monolithic heat exchanger body of claim 1 , wherein the conduction breaks are configured and arranged to reduce heat conduction from the combustion fins by an amount sufficient for the conduction fins to remain at a sufficiently high temperature to for fuel combustion to approach complete combustion within the portion of the heating fluid pathways disposed upstream from the conduction breaks.
19. The monolithic heat exchanger body of claim 1 , wherein the conduction breaks are located at a distance along the heating fluid pathways to allow for fuel combustion to approach complete combustion within the portion of the heating fluid pathways disposed upstream from the conduction breaks.
20. The monolithic heat exchanger body of claim 1 , wherein the plurality of heating walls, and/or the plurality of combustion fins, have a configuration and arrangement corresponding to at least a portion of one or more of the following: an Archimedean spiral, a Cornu spiral, a Fermat's spiral, a hyperbolic spiral, a logarithmic spiral, a Fibonacchi spiral, an involute, or a squircular spiral.