Refrigeration system with absorption cooling

Patent metadata

Field	Value
Publication number	US-9709302-B2
Application number	US-201314653783-A
Country	US
Kind code	B2
Filing date	Dec 19, 2013
Priority date	Dec 21, 2012
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

A refrigeration system for use with refrigerated LT and MT display cases in facilities such as supermarkets, has an absorption chiller that uses waste heat from a nearby source to provide cooling to the refrigeration system to take advantage of the synergy and improve overall efficiency of the refrigeration system. The cooling provided by the absorption chiller may be in the form of a coolant (e.g. water, glycol, water-glycol mixture, etc.) that circulates between the chiller and one or more of a pre-cooler, sub-cooler or condenser in the refrigeration system in a manner that uses waste heat from a nearby source to reduce the need for installed condensing capacity in the refrigeration system and improve thermal efficiency and obtain cost savings.

First claim

What is claimed is:

1. A refrigeration system having absorption chilling, comprising:
a low temperature portion and a medium temperature portion for circulating a CO2 refrigerant;
the low temperature portion comprising at least one low temperature compressor and at least one low temperature load;
the medium temperature portion comprising at least one medium temperature compressor and at least one medium temperature load;
a heat exchanger configured to cool or condense CO2 refrigerant in a hot gas state from the medium temperature compressor;
a sub-cooler configured to receive and cool the CO2 refrigerant from the heat exchanger;
an absorption chiller configured to receive waste heat from a source and provides cooling to the CO2 refrigerant in the sub-cooler;
a flash tank configured to receive the cooled CO2 refrigerant from the sub-cooler;
a CO2 refrigerant vapor line communicating between a vapor portion of the flash tank and a suction side of the medium temperature compressor; and
a CO2 refrigerant liquid line communicating between the flash tank and at least one of the medium temperature load and the low temperature load.

2. The refrigeration system of claim 1 wherein CO2 refrigerant discharged from the one of the medium temperature load and the low temperature load is directed to a suction side of the low temperature compressor, and CO2 refrigerant discharged from the low temperature compressor is directed to the suction side of the medium temperature compressor.

3. The refrigeration system of claim 2 further comprising an expansion valve configured to expand the CO2 refrigerant entering the flash tank.

4. The refrigeration system of claim 3 further comprising a control valve configured to direct the liquid CO2 refrigerant from the flash tank into the medium temperature load.

5. The refrigeration system of claim 4 further comprising an expansion valve configured to expand the liquid CO2 refrigerant from the flash tank into vapor and into the low temperature load.

6. A refrigeration system having absorption chilling, comprising:
a low temperature portion and a medium temperature portion for circulating an HFC refrigerant,
the low temperature portion comprising at least one low temperature compressor and at least one low temperature load, and at least one air-cooled low temperature condenser having a bypass valve, the air-cooled low temperature condenser configured to cool refrigerant in a hot gas state from the low temperature compressor;
the medium temperature portion comprising at least one medium temperature compressor and at least one medium temperature load, and at least one air-cooled medium temperature condenser configured to cool refrigerant in a hot gas state from the medium temperature compressor;
a medium temperature sub-cooler configured to receive and cool the refrigerant from the air-cooled medium temperature condenser;
a low temperature condenser/sub-cooler configured to receive and cool the refrigerant from the air-cooled low temperature condenser or directly from the low temperature compressor via the bypass valve;
an absorption chiller configured to receive waste heat from a source and provide cooling to the refrigerant in the medium temperature sub-cooler and to the refrigerant in the low temperature condenser/sub-cooler;
wherein the low temperature condenser/sub-cooler is configured as a primary source of condensing for refrigerant from the low temperature compressors, and the air-cooled low temperature condenser is configured to serve as a back-up for condensing the refrigerant from the low temperature compressors.

7. A cascade refrigeration system having absorption chilling, comprising:
a low temperature portion for circulating a CO2 refrigerant and a medium temperature portion for circulating an HFC refrigerant,
the low temperature portion comprising at least one low temperature compressor and at least one low temperature load;
the medium temperature portion comprising at least one medium temperature compressor and at least one medium temperature load, and at least one air-cooled medium temperature condenser configured to cool refrigerant in a hot gas state from the medium temperature compressor;
a medium temperature sub-cooler configured to receive and cool the refrigerant from the air-cooled medium temperature condenser;
a low temperature desuperheater configured to receive and cool the refrigerant from the low temperature compressor;
an absorption chiller configured to receive waste heat from a source and provide cooling to the HFC refrigerant in the medium temperature sub-cooler and to the CO2 refrigerant in the low temperature desuperheater;
a heat exchanger configured to receive the HFC refrigerant from the medium temperature subcooler and to receive the CO2 refrigerant from the low temperature desuperheater, so that the HFC refrigerant cools the CO2 refrigerant.

8. The cascade refrigeration system of claim 7 wherein the heat exchanger is a cascade heat exchanger configured in parallel with the medium temperature load and operable to evaporate the HFC refrigerant for return to the medium temperature compressor and to condense the CO2 refrigerant for return to a CO2 receiver.

9. The cascade refrigeration system of claim 8 wherein liquid CO2 refrigerant from the CO2 receiver is configured to be vaporized in the low temperature load and directed to a suction of the low temperature compressor.

10. A refrigeration system having absorption chilling, comprising:
a low temperature portion for circulating a CO2 refrigerant, a medium temperature primary portion for circulating an HFC refrigerant, and a medium temperature secondary portion for circulating a CO2 refrigerant;
the low temperature portion comprising at least one low temperature compressor and at least one low temperature load;
the medium temperature primary portion comprising at least one medium temperature compressor and at least one air-cooled medium temperature condenser configured to cool HFC refrigerant in a hot gas state from the medium temperature compressor;
the medium temperature secondary portion including at least one CO2 refrigerant pump for circulating CO2 refrigerant in a liquid state to at least one medium temperature load;
a medium temperature sub-cooler configured to receive and cool the HFC refrigerant from the air-cooled medium temperature condenser;
a low temperature desuperheater configured to receive and cool the CO2 refrigerant from the low temperature compressor;
an absorption chiller configured to receive waste heat from a source and to provide cooling to the HFC refrigerant in the medium temperature sub-cooler and to the CO2 refrigerant in the low temperature desuperheater;
a heat exchanger configured to receive the HFC refrigerant from the medium temperature subcooler and to receive the CO2 refrigerant from the low temperature desuperheater, so that the HFC refrigerant condenses the CO2 refrigerant;
a CO2 receiver configured to receive liquid CO2 refrigerant from the heat exchanger;
a CO2 refrigerant liquid line having a first branch configured to direct liquid CO2 refrigerant for expansion to the low temperature load, and a second branch configured to direct liquid CO2 refrigerant to the CO2 refrigerant pump for circulation of the liquid CO2 refrigerant to the medium temperature load in the medium temperature secondary portion.

Assignees

• Hill Phoenix Inc

Inventors

• Martin J Scott
• Zha Shitong
• Newel Jeffrey
• Lukes Timothy E
• Mccullough Willis L

Classifications

• F25B5/02

  arranged in parallel · CPC title

• F25B15/006 Primary

  with cascade operation · CPC title

• F25B25/02

  Compression-sorption machines, plants, or systems · CPC title

• F25B2400/061

  the capacity of the first system being different from the second · CPC title

• Y02B30/62

  Absorption based systems · CPC title