A throttle device to decompress a refrigerant and to deliver the refrigerant to an evaporator, may have an opening level of a needle valve controlled following a condensation pressure. Inside a case including a primary chamber connected to the condenser and a secondary chamber connected to the evaporator, a valve seat formed with a port and a guide integral to the valve seat are provided. A spring to energize the needle valve toward the port side is provided inside the guide. The guide guides the needle valve along a line allowing an opening level of the port to be variable. A space between the guide and the case forms a channel to deliver the refrigerant from the port to the secondary chamber. A rear space of the needle valve within the guide forms an intermediate chamber. An intermediate channel introduces the refrigerant from the port into the intermediate chamber.

The application relates to a cooling system, the cooling system having: an evaporator, a first compressor, a second compressor, a cooling component, an expansion device and a line system that connects the evaporator, the first compressor, the second compressor, the cooling component and the expansion device to one another. The cooling system includes a refrigerant, wherein the refrigerant comprises carbon dioxide. The first compressor and the second compressor are arranged in series with one another. The application also relates to a corresponding laboratory instrument.

The application relates to a cooling system, the cooling system having: an evaporator, a first compressor, a second compressor, a cooling component, an expansion device and a line system that connects the evaporator, the first compressor, the second compressor, the cooling component and the expansion device to one another. The cooling system includes a refrigerant, wherein the refrigerant comprises carbon dioxide. The first compressor and the second compressor are arranged in series with one another. The application also relates to a corresponding laboratory instrument.

The heat source unit includes a refrigerant control valve and a controller. If the opening degree of the refrigerant control valve changes, the high pressure of the refrigeration cycle changes. The controller adjusts the opening degree of the refrigerant control valve in a stepwise manner. The amount of change by one step in the opening degree of the refrigerant control valve is the unit change amount. The physical quantity indicating the high pressure of the refrigeration cycle is the high pressure index. The controller changes the unit change amount employed when the high pressure index is higher than the reference value to a value lower than the unit change amount employed when the high pressure index is lower than the reference value.

The heat source unit includes a refrigerant control valve and a controller. If the opening degree of the refrigerant control valve changes, the high pressure of the refrigeration cycle changes. The controller adjusts the opening degree of the refrigerant control valve in a stepwise manner. The amount of change by one step in the opening degree of the refrigerant control valve is the unit change amount. The physical quantity indicating the high pressure of the refrigeration cycle is the high pressure index. The controller changes the unit change amount employed when the high pressure index is higher than the reference value to a value lower than the unit change amount employed when the high pressure index is lower than the reference value.

Refrigeration systems are described. The systems include a refrigeration circuit having a compression device, a heat rejecting heat exchanger, an expansion device, and a heat absorbing heat exchanger. The refrigeration systems include one or more sensors configured to measure a pressure associated with the heat rejecting heat exchanger, and a controller configured to compare the pressure measured by the one or more sensors to a predicted pressure, and to control the expansion device on the basis of the comparison.

Refrigeration systems are described. The systems include a refrigeration circuit having a compression device, a heat rejecting heat exchanger, an expansion device, and a heat absorbing heat exchanger. The refrigeration systems include one or more sensors configured to measure a pressure associated with the heat rejecting heat exchanger, and a controller configured to compare the pressure measured by the one or more sensors to a predicted pressure, and to control the expansion device on the basis of the comparison.