Expander system

An apparatus (20) comprising:

• a compressor (22) having a suction port (24) and a discharge port (26);
• a heat rejection heat exchanger (30);
• a heat absorption heat exchanger (60);
• and
• at least one expansion-compression device (40;
• 200) coupling the heat absorption heat exchanger to the heat rejection heat exchanger and to the compressor and comprising:
• a pivoting member (98) mounted for reciprocal rotation in opposite first and second directions about an axis;
• a first variable volume chamber (80A) having an associated first wall formed by a first side of a first portion of the pivoting member;
• a second variable volume chamber (80B) having an associated second wall formed by a second side of the first portion of the pivoting member;
• a third variable volume chamber (80C) having an associated third wall formed by a first side of a second portion of the pivoting member;
• and
• a fourth variable volume chamber (80D) having an associated fourth wall formed by a second side of the second portion of the pivoting member,
• the expander apparatus having an asymmetric construction wherein the respective first and second walls of the first and second chambers differ in size, shape, and/or distance of the chamber from the axis from the respective third and fourth walls of the third and fourth chambers,
• wherein the pivoting member (98) is coupled to the chambers so that:
• rotation from the initial orientation in the first direction expands the first and third chambers and compresses the second and fourth chambers;
• and
• rotation from the initial orientation in the second direction compresses the first and third chambers and expands the second and fourth chambers.