US Patent 7185506 Reversible vapor compression system

Reversible vapor compression system including a compressor (1), an interior heat exchanger (2), an expansion device (6) and an exterior heat exchanger (3) connected by means of conduits in an operable relationship to form an integral main circuit. A first device is provided in the main circuit between the compressor and the interior heat exchanger, and a second device is provided on the opposite side of the main circuit between the interior and exterior heat exchangers to enable reversing of the system from cooling mode to heating mode and vice versa. The first and second device for reversing of the system include a first and second sub-circuit (A respectively B) each of which is connected with the main circuit through a flow reversing device (4 and 5 respectively). Included in the system solution is a reversible heat exchanger for refrigerant fluid, particularly carbon dioxide. It includes a number of interconnected sections arranged with air flow sequentially through the sections. The first and last sections are inter-connected whereby the refrigerant fluid flow in the heat exchanger can be changed from heating to cooling mode by means of flow changing devices provided between the respective sections.