# US 2019/0376732 A1 · Cooling system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0376732 A1 - Document ID: US20190376732A1 - Status: Published application - Kind: A1 - Application number: 16/001,296 - Filed: 2018-06-06 - Published: 2019-12-12 - Earliest claimed: 2018-06-06 - Assignees: Heatcraft Refrigeration Products LLC - Applicants: Heatcraft Refrigeration Products LLC - Inventors: Shitong Zha - Web page: https://patentgrep.com/patent/US20190376732A1 ## CPC - F25B 1/10: with multi-stage compression (with cascade operation F25B7/00) - F25B 47/025: {by reversing the cycle} - F25B 5/00: Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity (with cascade operation F25B7/00) - F25B 5/02: arranged in parallel - F25B 41/00: Fluid-circulation arrangements - F25B 47/006: {for preventing frost} - F25B 47/022: {hot gas defrosting} - F25B 2313/02791: using shut-off valves - F25B 2341/0014: Ejectors with a high pressure hot primary flow from a compressor discharge - F25B 2400/053: between the storage receiver and another part of the system - F25B 2400/075: with parallel compressors - F25B 2400/13: Economisers - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS ## Abstract An apparatus includes a flash tank, a medium temperature load, a low temperature load, a first compressor, a second compressor, and an ejector. The flash tank stores a refrigerant. The medium temperature load uses the refrigerant from the flash tank to cool a space proximate the medium temperature load to a first temperature. The low temperature load uses the refrigerant from the flash tank to cool a space proximate the low temperature load to a second temperature that is lower than the first temperature. The first compressor compresses the refrigerant from the low temperature load. The second compressor compresses the refrigerant from the medium temperature load. The ejector directs a mixture of the refrigerant from the first compressor and the refrigerant from the second compressor to the low temperature load during a defrost cycle. The mixture defrosts the low temperature load. The flash tank receives the mixture. ## Claims ### Claim 1 An apparatus comprising: a flash tank configured to store a refrigerant; a medium temperature load configured to use the refrigerant from the flash tank to cool a space proximate the medium temperature load to a first temperature; a low temperature load configured to use the refrigerant from the flash tank to cool a space proximate the low temperature load to a second temperature that is lower than the first temperature; a first compressor configured to compress the refrigerant from the low temperature load; a second compressor configured to compress the refrigerant from the medium temperature load; and an ejector configured to direct a mixture of the refrigerant from the first compressor and the refrigerant from the second compressor to the low temperature load during a defrost cycle, the mixture defrosts the low temperature load, the flash tank further configured to receive the mixture. ### Claim 2 (depends on 1) The apparatus of claim 1, further comprising a valve configured to direct a portion of the mixture from the flash tank to the second compressor. ### Claim 3 (depends on 1) The apparatus of claim 1, further comprising a valve configured to direct a portion of the refrigerant from the first compressor to the second compressor when a pressure of the refrigerant from the first compressor exceeds a threshold. ### Claim 4 (depends on 1) The apparatus of claim 1, further comprising a valve configured to direct the refrigerant from the second compressor to the ejector during the defrost cycle and to a high side heat exchanger after the defrost cycle ends. ### Claim 5 (depends on 1) The apparatus of claim 1, further comprising a second low temperature load configured to use the refrigerant from the flash tank to cool a space proximate the second low temperature load, the second compressor further configured to compress the refrigerant from the second low temperature load, the ejector further configured to direct the mixture to the second low temperature load during a second defrost cycle. ### Claim 6 (depends on 1) The apparatus of claim 1, further comprising a valve configured to stop a flow of the refrigerant from the flash tank to the low temperature load during the defrost cycle. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the ejector is further configured to direct the mixture to the medium temperature load during a third defrost cycle. ### Claim 8 A method comprising: storing, by a flash tank, a refrigerant; using, by a medium temperature load, the refrigerant from the flash tank to cool a space proximate the medium temperature load to a first temperature; using, by a low temperature load, the refrigerant from the flash tank to cool a space proximate the low temperature load to a second temperature that is lower than the first temperature; compressing, by a first compressor, the refrigerant from the low temperature load; compressing, by a second compressor, the refrigerant from the medium temperature load; directing, by an ejector, a mixture of the refrigerant from the first compressor and the refrigerant from the second compressor to the low temperature load during a defrost cycle, the mixture defrosts the low temperature load; and receiving, by the flash tank, the mixture. ### Claim 9 (depends on 8) The method of claim 8, further comprising directing, by a valve, a portion of the mixture from the flash tank to the second compressor. ### Claim 10 (depends on 8) The method of claim 8, further comprising directing, by a valve, a portion of the refrigerant from the first compressor to the second compressor when a pressure of the refrigerant from the first compressor exceeds a threshold. ### Claim 11 (depends on 8) The method of claim 8, further comprising directing, by a valve, the refrigerant from the second compressor to the ejector during the defrost cycle and to a high side heat exchanger after the defrost cycle ends. ### Claim 12 (depends on 8) The method of claim 8, further comprising: using, by a second low temperature load, the refrigerant from the flash tank to cool a space proximate the second low temperature load; compressing, by the second compressor, the refrigerant from the second low temperature load; and directing, by the ejector, the mixture to the second low temperature load during a second defrost cycle. ### Claim 13 (depends on 8) The method of claim 8, further comprising stopping, by a valve, a flow of the refrigerant from the flash tank to the low temperature load during the defrost cycle. ### Claim 14 (depends on 8) The method of claim 8, further comprising directing, by the ejector, the mixture to the medium temperature load during a third defrost cycle. ### Claim 15 A system comprising: a high side heat exchanger configured to remove heat from a refrigerant; a flash tank configured to store the refrigerant from the high side heat exchanger; a medium temperature load configured to use the refrigerant from the flash tank to cool a space proximate the medium temperature load to a first temperature; a low temperature load configured to use the refrigerant from the flash tank to cool a space proximate the low temperature load to a second temperature that is lower than the first temperature; a first compressor configured to compress the refrigerant from the low temperature load; a second compressor configured to compress the refrigerant from the medium temperature load; and an ejector configured to direct a mixture of the refrigerant from the first compressor and the refrigerant from the second compressor to the low temperature load during a defrost cycle, the mixture defrosts the low temperature load, the flash tank further configured to receive the mixture. ### Claim 16 (depends on 15) The system of claim 15, further comprising a valve configured to direct a portion of the mixture from the flash tank to the second compressor. ### Claim 17 (depends on 15) The system of claim 15, further comprising a valve configured to direct a portion of the refrigerant from the first compressor to the second compressor when a pressure of the refrigerant from the first compressor exceeds a threshold. ### Claim 18 (depends on 15) The system of claim 15, further comprising a valve configured to direct the refrigerant from the second compressor to the ejector during the defrost cycle and to the high side heat exchanger after the defrost cycle ends. ### Claim 19 (depends on 15) The system of claim 15, further comprising a second low temperature load configured to use the refrigerant from the flash tank to cool a space proximate the second low temperature load, the second compressor further configured to compress the refrigerant from the second low temperature load, the ejector further configured to direct the mixture to the second low temperature load during a second defrost cycle. ### Claim 20 (depends on 15) The system of claim 15, further comprising a valve configured to stop a flow of the refrigerant from the flash tank to the low temperature load during the defrost cycle. ### Claim 21 (depends on 15) The system of claim 15, wherein the ejector is further configured to direct the mixture to the medium temperature load during a third defrost cycle.