A gas-expansion cooler assembly has an expansion structure with an
expansion orifice and an expansion reservoir in fluid-flow communication
with an expansion-orifice outlet. A heat exchanger has a heat-exchanger
inlet, and a heat-exchanger outlet in fluid-flow communication with the
expansion-orifice inlet. The heat exchanger includes at least two
heat-exchanger plates stacked in a facing relationship along an assembly
axis. Each heat-exchanger plate includes an in-plane channel lying
substantially in a plane perpendicular to the assembly axis. The in-plane
channels of the adjacent heat-exchanger plates are in fluid-flow
communication with each other and with the expansion-orifice inlet to
form a continuous high-pressure fluid-flow path from the heat-exchanger
inlet to the expansion-orifice inlet. The heat exchanger further includes
an axial channel extending parallel to the assembly axis. The axial
channels in the adjacent heat-exchanger plates are in fluid-flow
communication with each other and with the expansion reservoir to form a
continuous exhaust fluid-flow path from the expansion reservoir to an
exhaust port.