US Patent 8235101 Parallel flow heat exchanger for heat pump applications

A parallel flow heat exchanger system (10, 50, 100, 200) for heat pump applications in which single and multiple paths of variable length are established via flow control systems which also allow for refrigerant flow reversal within the parallel flow heat exchanger system (10, 50, 100, 200), while switching between cooling and heating modes of operation. Examples of flow control devices are an expansion device (80) and various check valves (70, 72, 74, 76). The parallel flow heat exchanger system may have converging or diverging flow circuits and may constitute a single-pass or a multi-pass evaporator together with and a multi-pass condenser.