Gas-replenishing and enthalpy-increasing control method, device and apparatus for two-stage compressor

A gas-replenishing and enthalpy-increasing control device for a two-stage compressor, comprising:

• a gas-replenishing electronic expansion valve, disposed between a medium-pressure liquid storage tank and a two-stage compressor;
• and
• a controller, connected to the gas-replenishing electronic expansion valve, and configured to gradually increase an opening degree of the gas-replenishing electronic expansion valve in a time sequence when the gas-replenishing electronic expansion valve needs to be opened, acquire a gas-replenishing superheat degree of the two-stage compressor after the gas-replenishing electronic expansion valve is opened, and adjust the opening degree of the gas-replenishing electronic expansion valve based on the gas-replenishing superheat degree of the two-stage compressor;
• a detection apparatus, connected to the controller, and configured to collect a gas-replenishing temperature and a gas-replenishing pressure of the two-stage compressor,
• wherein the controller comprises:
• a reading apparatus, connected to the detection apparatus, and configured to read a saturation temperature corresponding to the gas-replenishing pressure;
• and
• a calculator, connected to the detection apparatus and the reading apparatus, and configured to calculate a difference between the gas-replenishing temperature and the saturation temperature, so as to obtain the gas-replenishing superheat degree;
• wherein the controller is further configured to:
• when the gas-replenishing superheat degree of the two-stage compressor is greater than the preset superheat degree, determine that the replenished gas of the two-stage compressor entrains liquid, and reduce the current opening degree of the gas-replenishing electronic expansion valve to a preset opening degree, wherein the preset opening degree is an opening degree preset based on a full opening degree of the gas-replenishing electronic expansion valve, and the full opening degree is an opening degree when the gas-replenishing electronic expansion valve is fully opened
• when the gas-replenishing superheat degree of the two-stage compressor is not greater than the preset superheat degree, determine that the replenished gas of the two-stage compressor does not entrain liquid, and keep the current opening degree of the gas-replenishing electronic expansion valve unchanged or increasing the current opening degree.

A gas-replenishing and enthalpy-increasing control apparatus for a two-stage compressor, comprising:

• a control unit, configured to allow, when a gas-replenishing electronic expansion valve needs to be opened, a controller to gradually increase an opening degree of the gas-replenishing electronic expansion valve in a time sequence;
• an acquisition unit, configured to acquire, after the gas-replenishing electronic expansion valve is opened, a detected gas-replenishing superheat degree of a two-stage compressor;
• and
• an adjustment unit, configured to adjust, based on the gas-replenishing superheat degree of the two-stage compressor, the opening degree of the gas-replenishing electronic expansion valve,
• wherein the gas-replenishing electronic expansion valve is disposed between a medium-pressure liquid storage tank and the two-stage compressor, and when the opening degree of the gas-replenishing electronic expansion valve is not zero, a gaseous refrigerant in the medium-pressure liquid storage tank replenishes gas and increases enthalpy for the two-stage compressor;
• wherein the acquisition unit comprises:
• a collection module, configured to collect a gas-replenishing temperature and a gas-replenishing pressure of the two-stage compressor;
• an acquisition module, configured to acquire a saturation temperature corresponding to the gas-replenishing pressure;
• and
• a calculation module, configured to take a difference between the gas-replenishing temperature and the saturation temperature as the gas-replenishing superheat degree of the two-stage compressor;
• wherein the adjustment unit comprises:
• a judgment module, configured to judge whether the gas-replenishing superheat degree of the two-stage compressor is greater than a preset superheat degree at predetermined intervals;
• a first determination module, configured to determine that, if the gas-replenishing superheat degree of the two-stage compressor is greater than the preset superheat degree, the replenished gas of the two-stage compressor entrains liquid;
• a second determination module, configured to determine that, if the gas-replenishing superheat degree of the two-stage compressor is not greater than the preset superheat degree, the replenished gas of the two-stage compressor does not entrain liquid;
• and
• an adjustment module, configured to adjust the opening degree of the gas-replenishing electronic expansion valve according to the situation that the replenished gas of the two-stage compressor entrains liquid;
• wherein the adjustment unit is further configured to:
• when the replenished gas of the two-stage compressor entrains liquid, reduce the current opening degree of the gas-replenishing electronic expansion valve to a preset opening degree, wherein the preset opening degree is an opening degree preset based on a full opening degree of the gas-replenishing electronic expansion valve, and the full opening degree is an opening degree when the gas-replenishing electronic expansion valve is fully opened;
• and
• when the replenished gas of the two-stage compressor does not entrain liquid, keep the current opening degree of the gas-replenishing electronic expansion valve unchanged or increasing the current opening degree.