Single-refrigeration type air conditioner and control method thereof

The invention discloses a single-refrigeration type air conditioner and a control method thereof.The air conditioner comprises a double-cylinder compressor, an outdoor heat exchanger, an indoor heat exchanger, a gas-liquid separator and a cold medium cooler.The gas suction opening of a first cylinder is communicated with a first liquid storage device.The exhaust volume ratio of a second cylinder to the exhaust volume ratio of the first cylinder ranges from 1% to 10%.The gas-liquid separator comprises a gas outlet, a first connector and a second connector.The gas outlet is connected with the second cylinder.A first throttling element for fixing the opening degree is connected between the first connector and the outdoor heat exchanger in series.A second throttling element for fixing the opening degree is connected between the second connector and the indoor heat exchanger in series.The cold medium cooler is connected between the first throttling element and the first connector in series, or the cold medium cooler is connected between the second throttling element and the second connector in series.The efficiency of the single-refrigeration type air conditioner is effectively improved.