Air conditioning system using heat pump

The present invention provides an air conditioning system using a heat pump, which comprises: a compression unit which compresses low-temperature and low-pressure gaseous refrigerant into high-temperature and high-pressure gaseous refrigerant and provides the compressed refrigerant; a first coil which is connected to the compression unit and a flow path through which the refrigerant flows, and condenses or evaporates the refrigerant flowing according to a flow direction of the refrigerant changed by a cooling operation or a heating operation; a second coil which is connected in parallel with the first coil and the flow path through which the refrigerant flows, and reheats supply air with condensation heat of the refrigerant selectively introduced according to a cooling load and the humidity of the supply air; a third coil which is connected to the first coil and the second coil by the flow path through which the refrigerant flows, and condenses or evaporates the refrigerant flowing according to the flow direction of the refrigerant changed by the cooling operation or the heating operation; an expansion valve which is provided at one side of the third coil to expand the condensed refrigerant to a low temperature and low pressure, and provides the refrigerant to the third coil; a four-way flow path switching valve which is connected to refrigerant paths connected to inlet and discharge sides of the compression unit, and refrigerant paths connected to one side of the first coil and the other side of the third coil, and changes the flow direction of the refrigerant according to the cooling operation and the heating operation; and a three-way control valve which is provided at a branch point at which a fourth refrigerant path branches in the first refrigerant path, and controls the opening degree of the fourth refrigerant path according to the required amount of reheat of the supply air. Therefore, precise temperature control is possible. 본 발명은 저온저압의 기상냉매를 고온고압의 기상냉매로 압축하여 제공하는 압축부와, 상기 압축부와 냉매가 유동하는 유로로 연결되고, 냉방운전 또는 난방운전에 의해 변경되는 냉매의 유동방향에 따라 유동하는 냉매를 응축 또는 증발 시키는 제1코일과, 상기 제1코일과 냉매가 유동하는 유로로 병렬로 연결되고, 냉방부하 및 급기의 습도에 따라 선택적으로 유입되는 냉매의 응축열로 급기를 재열하는 제2코일과, 상기 제1코일 및 제2코일과 냉매가 유동하는 유로로 연결되고, 냉방운전 또는 난방운전에 의해 변경되는 냉매의 유동방향에 따라 유동하는 냉매를 응축 또는 증발 시키는 제3코일과, 상기 제3코일의 일측에 구비되어 응축된 냉매를 저온, 저압으로 감압되도록 팽창시킨 후 상기 제3코일로 제공하는 팽창밸브와, 상기 압축부의 유입측 및 토출측과 연결된 냉매유로들과, 상기 제1코일의 일측 및 제3코일의 타측과 연결된 냉매유로들과 연결되어, 냉방운전 및 난방운전에 따라 냉매의 유동방향을 변경하는 사방유로전환밸브, 및 제1냉매유로 중 제4냉매유로가 분기되는 분기점에