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A heat exchanger and a method are provided to vaporize a working fluid using a heat sourcing fluid. The heat exchanger includes a first section, a second section, and a third section. A first portion of the heat sourcing fluid passes through the first section, in counter-flow with the working fluid.

A heat exchanger and a method are provided to vaporize a working fluid using a heat sourcing fluid. The heat exchanger includes a first section, a second section, and a third section. A first portion of the heat sourcing fluid passes through the first section, in counter-flow with the working fluid. A second portion of the heat sourcing fluid passes through the second section, in co-flow with the working fluid. Both the first and second portions pass through the third section, in overall counter-flow with the working fluid. The working fluid passes sequentially through the third section, the first section, and the second section. The heat exchanger and/or the method may be used in a Rankine cycle for waste heat recovery or in a refrigerant cycle.

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1. A heat exchanger to vaporize a working fluid with heat from a hot gas, the heat exchanger comprising: a hot gas inlet located at a first end of the heat exchanger;a hot gas outlet located at a second end of the heat exchanger opposite the first end;a hot gas flow path extending from the hot gas i

1. A heat exchanger to vaporize a working fluid with heat from a hot gas, the heat exchanger comprising: a hot gas inlet located at a first end of the heat exchanger;a hot gas outlet located at a second end of the heat exchanger opposite the first end;a hot gas flow path extending from the hot gas inlet to the hot gas outlet and comprising first and second pluralities of parallel hot gas flow conduits; anda working fluid flow path extending from a working fluid inlet adjacent to the second end to a working fluid outlet spaced apart from the second end and the first end and comprising: a first section adjacent to the second end and fluidly connected to the working fluid inlet to receive a flow of working fluid therefrom and configured to transfer heat to the working fluid from a flow of hot gas passing through the first and second pluralities of hot gas flow conduits;a second section fluidly connected to the first section to receive the working fluid therefrom and extending to the first end, the second section configured to transfer heat to the working fluid from the first plurality of hot gas flow conduits but not from the second plurality of hot gas flow conduits; anda third section extending from the first end to the working fluid outlet and fluidly connected to the working fluid outlet to deliver the flow of working fluid thereto and fluidly connected to the second section to receive the working fluid therefrom, the third section configured to transfer heat to the working fluid from the second plurality of hot gas flow conduits but not from the first plurality of hot gas flow conduits. 2. The heat exchanger of claim 1, wherein the second section of the working fluid flow path is in counter-flow orientation to the first plurality of hot gas flow conduits and wherein the third section of the working fluid flow path is in co-flow orientation to the second plurality of hot gas flow conduits. 3. The heat exchanger of claim 1, wherein the first and second ends define a longitudinal direction of the heat exchanger, the first plurality of hot gas flow conduits is centrally located along a transverse direction normal to the longitudinal direction, and the second plurality of hot gas flow conduits is located at opposing ends of the heat exchanger in the transverse direction. 4. The heat exchanger of claim 1, further comprising: a plurality of plate pairs, each comprising a first plate and a second plate spaced apart to at least partially define the working fluid flow path therebetween; andfins located between adjacent ones of the plurality of plate pairs, the fins and plate pairs together at least partially defining the first and second pluralities of parallel hot gas flow conduits. 5. The heat exchanger of claim 1, wherein the working fluid outlet is adjacent to the first section and spaced apart from the heat sourcing fluid outlet by the first section, and wherein the working fluid outlet is spaced apart from the heat sourcing fluid inlet by the third section. 6. The heat exchanger of claim 1, wherein the first section includes a first cross- counter flow path section and a second cross-counter flow path section, wherein the first cross-counter flow path section is upstream of the second cross-counter flow path section and defines a more tortuous flow path than the second cross-counter flow path section. 7. The heat exchanger of claim 1, wherein the first section includes a plurality of cross-flow paths relative to the heat sourcing fluid flow path and a plurality of counter-flow paths relative to the heat sourcing fluid flow path. 8. The heat exchanger of claim 4, wherein the third section is fluidly connected to the second section by way of portions of the working fluid flow path located between the first and second plates of each of the plurality of plate pairs. 9. The heat exchanger of claim 4, each of the plurality of plate pairs further comprising an insert, the insert and the first and second plates together defining a plurality of parallel flow channels for the working fluid. 10. The heat exchanger of claim 9, wherein the insert comprises a formed plate having corrugations formed therein to at least partially define the plurality of parallel flow channels for the working fluid on both a first side and an opposite second side of the formed plate. 11. The heat exchanger of claim 9, wherein the insert comprises a first and a second essentially planar stacked metal sheets, each sheet including a plurality of openings, the openings in the first sheet cooperating with the openings in the second sheet to at least partially define the plurality of parallel flow channels for the working fluid, and wherein the first sheet is a mirror image of the second sheet. 12. The heat exchanger of claim 6, wherein the first cross-counter flow path section is adjacent to the working fluid inlet. 13. The heat exchanger of claim 7, wherein the plurality of cross-flow paths includes successive cross-flow paths extending in opposing directions. 14. A heat exchanger to transfer heat from a heat sourcing fluid to a working fluid, comprising: a heat sourcing fluid flow path extending in a longitudinal direction of the heat exchanger from a heat sourcing fluid inlet to a heat sourcing fluid outlet; anda working fluid flow path extending from a working fluid inlet to a working fluid outlet, having a plurality of flow arrangements with respect to the heat sourcing fluid flow path including a counter-cross-flow arrangement, a counter-flow arrangement, and a co-flow arrangement, the working fluid flow path comprising:a first section, fluidly connected to the working fluid inlet to receive a flow of working fluid therefrom, defining the counter-cross-flow arrangement;a second section, fluidly connected to the first section to receive the working fluid therefrom, defining the counter-flow arrangement; anda third section, fluidly connected to the working fluid outlet to deliver the flow of working fluid thereto and fluidly connected to the second section to receive the working fluid therefrom, defining the co-flow arrangement. 15. The heat exchanger of claim 14, wherein the second section and the third section extend over a common portion of the heat exchanger along the longitudinal direction. 16. The heat exchanger of claim 14, wherein the first section is adjacent to the heat sourcing fluid outlet and wherein both the second and the third sections are adjacent to the heat sourcing fluid inlet. 17. The heat exchanger of claim 14, wherein the heat sourcing fluid flow path comprises a first and a second plurality of flow channels extending continuously through the heat exchanger, fluid flowing through the first plurality of flow channels transferring heat to fluid flowing through the second section of the working fluid flow path but not through fluid flowing through the third section of the working fluid flow path, and fluid flowing through the second plurality of flow channels transferring heat to fluid flowing through the third section of the working fluid flow path but not through fluid flowing through the first section of the working fluid flow path. 18. The heat exchanger of claim 14, wherein the first section includes a fluid distribution region immediately adjacent the working fluid inlet. 19. The heat exchanger of claim 17, wherein fluid flowing through the first plurality of flow channels transfers heat to fluid flowing through the first section of the working fluid flow path after having first transferred heat to fluid flowing through the second section of the working fluid flow path, and wherein fluid flowing through the second plurality of flow channels transfers heat to fluid flowing through the first section of the working fluid flow path after having first transferred heat to fluid flowing through the third section of the working fluid flow path. 20. A heat exchanger to transfer heat from a heat sourcing fluid to a working fluid, comprising: a heat sourcing fluid inlet located at a first end of the heat exchanger;a heat sourcing fluid outlet located at a second end of the heat exchanger opposite the first end;a heat sourcing fluid flow path extending from the heat sourcing fluid inlet to the heat sourcing fluid outlet and comprising first and second pluralities of parallel heat sourcing fluid flow conduits; anda plurality of working fluid flow passages to convey the working fluid through the heat exchanger, each of the working fluid flow passages including: a first portion wherein the working fluid travels in a cross-counter flow orientation to the heat sourcing fluid and wherein the working fluid receives heat from the heat sourcing fluid in both the first and second pluralities of parallel heat sourcing fluid flow conduits;a second portion downstream of the first portion wherein the working fluid travels in a counter-flow orientation to the heat sourcing fluid and wherein the working fluid receives heat from the heat sourcing fluid in the first plurality of parallel heat sourcing fluid flow conduits but not from the heat sourcing fluid in the second plurality of parallel heat sourcing fluid flow conduits; anda third portion downstream of the second portion wherein the working fluid travels in a co-flow orientation to the heat sourcing fluid and wherein the working fluid receives heat from the heat sourcing fluid in the second plurality of parallel heat sourcing fluid flow conduits but not from the heat sourcing fluid in the first plurality of parallel heat sourcing fluid flow conduits. 21. The heat exchanger of claim 20, wherein each of the plurality of working fluid passages are hydraulically isolated from one another along at least the first, second, and third portions. 22. The heat exchanger of claim 20, wherein the plurality of working fluid flow passages are defined by inserts between pairs of flat plates. 23. The heat exchanger of claim 22, wherein the inserts comprise corrugated formed plates. 24. The heat exchanger of claim 22, wherein the inserts comprise a first and a second essentially planar stacked metal sheets, each sheet including a plurality of openings, the openings in the first sheet cooperating with the openings in the second sheet to at least partially define the plurality of working fluid flow passages.