Air-cooled ammonia refrigeration systems and methods
In some embodiments, an air-cooled ammonia refrigeration system comprises: an air-cooled condenser comprising a heat exchanger and at least one axial fan; an evaporator coupled to the air-cooled condenser; a subcooler positioned between the air-cooled condenser and the evaporator; a compressor coupled to the evaporator; an oil cooler coupled to the compressor; a water system coupled to the air-cooled condenser, the water system comprising a water source, a water pump, and a plurality of spray nozzles positioned below the air-cooled condenser; and a control circuit coupled to the air-cooled condenser and the water system, the control circuit configured to pulse atomized water through the plurality of spray nozzles to a surface of the air-cooled condenser when a head pressure of the air-cooled condenser is higher than a predetermined value.
1. An air-cooled ammonia refrigeration system, the system comprising:
an air-cooled condenser comprising a heat exchanger and at least one axial fan, the air-cooled condenser configured to condense vaporous ammonia to form liquid ammonia;
an evaporator coupled to the air-cooled condenser and configured to evaporate liquid ammonia received from the air-cooled condenser to form vaporous ammonia;
a subcooler positioned between the air-cooled condenser and the evaporator and configured to remove heat from the liquid ammonia passing from the air-cooled condenser to the evaporator;
a compressor coupled to the evaporator and configured to compress the vaporous ammonia received from the evaporator;
an oil cooler coupled to the compressor and configured to remove heat from circulating oil in the compressor;
a water system coupled to the air-cooled condenser, the water system comprising a water source, a water pump, and a plurality of spray nozzles positioned below the air-cooled condenser; and
a control circuit coupled to the air-cooled condenser and the water system, the control circuit configured to pulse atomized water through the plurality of spray nozzles to a surface of the air-cooled condenser when a head pressure of the air-cooled condenser is higher than a predetermined value.
2. The system of claim 1 , wherein the control circuit pulses the atomized water such that the atomized water evaporates upon contact with the surface of the air-cooled condenser.
3. The system of claim 1 , wherein the atomized water contains a water softening agent.
4. The system of claim 1 , wherein the heat exchanger comprises a finned tube heat exchanger.
5. The system of claim 4 , wherein the finned tube heat exchanger has a tube diameter of at least about 0.5 inches and a fin density of at least about 12 fins per inch.
6. The system of claim 1 , wherein the system further comprises a plurality of legs configured to elevate the heat exchanger at least about 13 feet above a roof surface.
7. The system of claim 1 , wherein the system further comprises a plurality of legs configured to elevate the heat exchanger at least about 25 feet above a ground surface.
8. The system of claim 1 , further comprising:
a high pressure receiver coupled to the air-cooled condenser; and
a recirculator coupled to the evaporator,
wherein the high pressure receiver receives the liquid ammonia from the air-cooled condenser and the recirculator receives liquid ammonia from the high pressure receiver that has been cooled by the subcooler.
9. The system of claim 8 , wherein the high pressure receiver is further coupled to the compressor to provide liquid ammonia to cool the oil in the oil cooler that is coupled to the compressor.
10. A method of providing refrigeration using an air-cooled ammonia refrigeration system, the method comprising: supplying vaporous ammonia to an air-cooled condenser comprising a heat exchanger and at least one axial fan; condensing, with the air-cooled condenser, the vaporous ammonia to form liquid ammonia; removing, with a subcooler, heat from the liquid ammonia; evaporating, with an evaporator, the liquid ammonia from the subcooler to form vaporous ammonia; and pulsing, with a control circuit, atomized water through a plurality of spray nozzles positioned below the air-cooled condenser to a surface of the air-cooled condenser when a head pressure of the air-cooled condenser is higher than a predetermined value; and wherein the atomized water is pulsed by the control circuit such that the atomized water evaporates upon contact with the surface of the air-cooled condenser.
11. The method of claim 10 , further comprising:
flowing the vaporous ammonia to a compressor and compressing the vaporous ammonia; and
flowing the vaporous ammonia back to the air-cooled condenser.
12. The method of claim 11 , further comprising removing, with an oil cooler, heat from circulating oil in the compressor.
13. The method of claim 10 , wherein the atomized water contains a water softening agent.
14. The method of claim 10 , wherein the heat exchanger is a finned tube heat exchanger.
15. The system of claim 14 , wherein the finned tube heat exchanger has a tube diameter of at least about 0.5 inches and a fin density of at least about 12 fins per inch.
16. The method of claim 10 , wherein the system further comprises a plurality of legs configured to elevate the heat exchanger at least about 13 feet above a roof surface.
17. The method of claim 10 , wherein the system further comprises a plurality of legs configured to elevate the heat exchanger at least about 25 feet above a ground surface.
18. The method of claim 10 , wherein the liquid ammonia is flowed from the air-cooled condenser to a high pressure receiver, from the high pressure receiver to a recirculator via the subcooler, and from the recirculator to the evaporator.
19. The method of claim 18 , wherein the liquid ammonia is flowed from the high pressure receiver to the compressor to cool the oil in the oil cooler that is coupled to the compressor.
20. An air-cooled ammonia refrigeration system, the system comprising:
an air-cooled condenser comprising a finned tube heat exchanger having a tube diameter of at least about 0.5 inches and a fin density of at least about 12 fins per inch, and at least one axial fan, the air-cooled condenser configured to condense vaporous ammonia to form liquid ammonia;
an evaporator coupled to the air-cooled condenser and configured to evaporate liquid ammonia received from the air-cooled condenser to form vaporous ammonia;
a subcooler positioned between the air-cooled condenser and the evaporator and configured to remove heat from the liquid ammonia passing from the air-cooled condenser to the evaporator;
a compressor coupled to the evaporator and configured to compress the vaporous ammonia received from the evaporator;
an oil cooler coupled to the compressor and configured to remove heat from circulating oil in the compressor;
a water system coupled to the air-cooled condenser, the water system comprising a water source, a water pump, and a plurality of spray nozzles positioned below the air-cooled condenser;
a control circuit coupled to the air-cooled condenser and the water system, the control circuit configured to pulse atomized water through the plurality of spray nozzles to a surface of the air-cooled condenser when a head pressure of the air-cooled condenser is higher than a predetermined value such that the atomized water evaporates upon contact with the surface of the air-cooled condenser; and
a plurality of legs configured to elevate the heat exchanger at least about 10 feet above a roof surface or at least about 20 feet above a ground surface.