Abstract: A carbon dioxide vapor compression system including a compressor, a first heat exchanger, an expansion device arrangement, and a second heat exchanger connected in a closed loop. The expansion device arrangement includes an inlet line disposed between the first heat exchanger and the expansion devices and an outlet line disposed between the expansion devices and the second heat exchanger. The expansion device arrangement includes at least three expansion devices with a fixed and variable expansion device being in parallel arrangement and another fixed expansion device being arranged in series with the parallel fixed and variable expansion devices. The expansion device arrangement may also include a flow path that extends from the inlet line to the outlet line and which includes only fixed expansion devices to provide a functional flow path through the expansion device arrangement if the variable expansion device fails.

Abstract: A compressor assembly including a cylinder block defining first and second cavity portions. A central axis extends through first and second cavity portions. A compressible fluid respectively enters and exits the first cavity portion through an inlet and outlet. A piston is reciprocatingly disposed along the central axis and includes first and second piston portions which are at least partially disposed within the first and second cavity portions, respectively. The first piston portion defines a compression chamber within the first cavity portion. Reciprocation of the piston compresses the fluid within compression chamber. The second piston portion has a radial outer surface at least partially engageable with a sidewall of second cavity portion whereby forces transverse to the central axis are transferable between the radial outer surface and the sidewall. A variable volume space is defined by the second piston and cavity portions. A vent passage communicates with the variable volume space.

Abstract: A compressor assembly having a piston with multiple cross sections. The compressor assembly, in one form thereof, includes a cylinder block defining a cavity. A piston is at least partially disposed in the cavity and reciprocates along a central axis of the cavity. The piston includes a first piston portion and a second piston portion. The first piston portion has a cross sectional configuration and area substantially similar to a first portion of the cavity and the second piston portion has a radially outer surface at least partially engageable with the sidewall of a second portion of the cavity. The second piston portion may also have a larger cross sectional area than the first portion of the piston which may be used to compress a refrigerant within the cavity.