US 2026/0210604 A1Published application

Two-stage compression in a medium-temperature co2 cdu application

AssigneeHeatcraft Refrigeration Products LLC

InventorsDaqing Li, Shitong Zha

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Abstract

A refrigeration system includes a switching valve configured to pass heated refrigerant from an evaporator that cools a load to the first compressor when in the first position and to pass the heated refrigerant to the second compressor when in a second position. The second compressor is configured to receive either refrigerant from the first compressor or the evaporator, depending on the position of the switching valve. The second compressor compresses the received refrigerant to produce compressed refrigerant, which is then used by the refrigeration system after cooling it with a gas cooler by the evaporator. The controller determines an ambient temperature using the ambient temperature sensor and causes the switching valve to be in the first position when the ambient temperature is greater than a predetermined threshold and causes the switching valve to be in the second position when the ambient temperature is less than the predetermined threshold.

Claims20

Dependent claims

A refrigeration system, comprising:

an evaporator configured to receive cooled refrigerant and facilitate the cooled refrigerant to absorb heat from a load to produce heated refrigerant;
a switching valve configured to receive the heated refrigerant from the evaporator and pass the heated refrigerant to a first compressor when in a first position and to pass the heated refrigerant to a second compressor when in a second position;
the first compressor configured to receive the heated refrigerant from the switching valve when the switching valve is in the first position and compress the heated refrigerant to produce a first compressed refrigerant;
the second compressor is configured to produce a second compressed refrigerant, wherein:
the second compressor is configured to receive the first compressed refrigerant from the first compressor when the switching valve is in the first position and provide additional compression to the first compressed refrigerant to produce the second compressed refrigerant, and
the second compressor is configured to receive the heated refrigerant from the switching valve when the switching valve is in the second position and compress the heated refrigerant to produce the second compressed refrigerant;
a gas cooler configured to receive the second compressed refrigerant from the second compressor and cool the second compressed refrigerant with ambient air to produce the cooled refrigerant and pass the cooled refrigerant to the evaporator;
an ambient temperature sensor associated with the gas cooler, wherein the ambient temperature sensor is configured to determine an ambient temperature of an environment at the gas cooler;
and
a controller communicatively coupled to the switching valve, wherein the controller is configured to:
determine the ambient temperature using the ambient temperature sensor;
cause the switching valve to be in the first position when the ambient temperature is greater than a predetermined threshold;
and
cause the switching valve to be in the second position when the ambient temperature is less than the predetermined threshold.

11 more elements

A method of operating a refrigeration system, the method comprising:

operating an evaporator to absorb heat from a load to produce heated refrigerant from received cooled refrigerant;
determining an ambient temperature using an ambient temperature sensor associated with a gas cooler, wherein the ambient temperature sensor is configured to determine an ambient temperature of an environment at the gas cooler;
causing a switching valve to be in a first position when the ambient temperature is greater than a predetermined threshold and to be in a second position when the ambient temperature is less than the predetermined threshold, wherein the switching valve is configured to receive the heated refrigerant from the evaporator and pass the heated refrigerant to a first compressor when in a first position and to pass the heated refrigerant to a second compressor when in a second position;
operating the first compressor to compress the heated refrigerant to produce a first compressed refrigerant, wherein the first compressor is configured to receive the heated refrigerant from the switching valve when the switching valve is in the first position and compress the heated refrigerant to produce the first compressed refrigerant;
operating a second compressor to produce a second compressed refrigerant wherein:
the second compressor is configured to receive the first compressed refrigerant from the first compressor when the switching valve is in the first position and provide additional compression to the first compressed refrigerant to produce the second compressed refrigerant, and
the second compressor is configured to receive the heated refrigerant from the switching valve when the switching valve is in the second position and compress the heated refrigerant to produce the second compressed refrigerant;
and
operating the gas cooler to cool the second compressed refrigerant with ambient air to produce the cooled refrigerant and pass the cooled refrigerant to the evaporator.

6 more elements

A controller of a refrigeration system, the controller comprising:

an input/output interface communicatively coupled to:
an evaporator configured to receive cooled refrigerant and facilitate the cooled refrigerant to absorb heat from a load to produce heated refrigerant;
a switching valve configured to receive the heated refrigerant from the evaporator and pass the heated refrigerant to a first compressor when in a first position and to pass the heated refrigerant to a second compressor when in a second position;
the first compressor configured to receive the heated refrigerant from the switching valve when the switching valve is in the first position and compress the heated refrigerant to produce a first compressed refrigerant;
the second compressor is configured to produce a second compressed refrigerant, wherein:
the second compressor is configured to receive the first compressed refrigerant from the first compressor when the switching valve is in the first position and provide additional compression to the first compressed refrigerant to produce the second compressed refrigerant, and
the second compressor is configured to receive the heated refrigerant from the switching valve when the switching valve is in the second position and compress the heated refrigerant to produce the second compressed refrigerant;
a gas cooler configured to receive the second compressed refrigerant from the second compressor and cool the second compressed refrigerant with ambient air to produce the cooled refrigerant and pass the cooled refrigerant to the evaporator;
and
an ambient temperature sensor associated with the gas cooler, wherein the ambient temperature sensor is configured to determine an ambient temperature of an environment at the gas cooler;
and
a processor configured to:
determine the ambient temperature using the ambient temperature sensor;
cause the switching valve to be in the first position when the ambient temperature is greater than a predetermined threshold;
and
cause the switching valve to be in the second position when the ambient temperature is less than the predetermined threshold.

13 more elements

Dependencies are inferred from the claim text.

Facts

Application: 19/028,334Filed 17 Jan 2025
Published: 23 Jul 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification15 codes

F25B 49/02
Arrangement or mounting of control or safety devices: for compression type machines, plants or systems
F25B 1/10
Compression machines, plants or systems with non-reversible cycle: with multi-stage compression
F25B 41/22
Disposition of valves, e.g. of on-off valves or flow control valves: between evaporator and compressor
F25B 5/02
Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity: arranged in parallel