Systems and methods for controlling a refrigeration system

Patent metadata

Field	Value
Publication number	US-2017227263-A1
Application number	US-201715427953-A
Country	US
Kind code	A1
Filing date	Feb 8, 2017
Priority date	Feb 10, 2016
Publication date	Aug 10, 2017
Grant date	—

Abstract

A refrigeration system includes a free cooling system having an air-cooled heat exchanger, where the air-cooled heat exchanger includes a fan configured to move air over coils of the air-cooled heat exchanger to remove heat from a coolant flowing through the air-cooled heat exchanger, and a mechanical cooling system with a refrigerant loop that includes an evaporator, a compressor, and a condenser disposed along the refrigerant loop, where the compressor is configured to circulate a refrigerant through the refrigerant loop, and wherein the evaporator is configured to receive the coolant and transfer heat from the coolant to the refrigerant. The refrigeration system also includes a controller configured to adjust a fan speed of the fan up to a threshold fan speed, to initiate operation of the compressor when the fan speed reaches the threshold fan speed, wherein the fan speed and a compressor speed of the compressor are based at least on an ambient air temperature and a cooling load demand.

First claim

1 . A refrigeration system, comprising:
a free cooling system comprising an air-cooled heat exchanger, wherein the air-cooled heat exchanger comprises a fan configured to move air over coils of the air-cooled heat exchanger to remove heat from a coolant flowing through the air-cooled heat exchanger; a mechanical cooling system comprising a refrigerant loop with an evaporator, a variable speed compressor, and a condenser disposed along the refrigerant loop, wherein the variable speed compressor is configured to circulate a refrigerant through the refrigerant loop, and wherein the evaporator is configured to receive the coolant and to transfer heat from the coolant to the refrigerant; and a controller configured adjust a fan speed of the fan up to a threshold fan speed, to initiate operation of the variable speed compressor when the fan speed reaches the threshold fan speed, wherein the fan speed and a compressor speed of the variable speed compressor are based at least on an ambient air temperature and a cooling load demand, and wherein the threshold fan speed is less than a maximum speed of the fan.

2 . The refrigeration system of claim 1 , wherein the controller is configured to adjust the fan speed and the compressor speed to achieve a desired cooling load demand at a minimum energy input.

3 . The refrigeration system of claim 1 , wherein the free cooling system, the mechanical cooling system, and the controller are packaged in a single unit, such that the refrigeration system is an autonomous unit.

4 . The refrigeration system of claim 1 , wherein the controller is configured to adjust the compressor speed and to maintain the fan speed at the threshold fan speed when the fan speed reaches the threshold fan speed.

5 . The refrigeration system of claim 1 , wherein the threshold fan speed is determined by the controller based at least on one or both of the ambient air temperature and a temperature of the coolant exiting the evaporator.

6 . The refrigeration system of claim 1 , wherein the controller is configured to adjust the fan speed to substantially zero when the temperature of ambient air reaches a threshold temperature.

7 . The refrigeration system of claim 1 , wherein the coolant comprises glycol.

8 . The refrigeration system of claim 1 , wherein the condenser of the refrigerant loop comprises an air-cooled condenser.

9 . The refrigeration system of claim 8 , wherein the air-cooled condenser is downstream of the air-cooled heat exchanger with respect to a flow of the air.

10 . The refrigeration system of claim 1 , comprising a temperature sensor configured to monitor the ambient air temperature and to provide the ambient air temperature as feedback to the controller.

11 . The refrigeration system of claim 1 , wherein the mechanical cooling system comprises an additional refrigerant loop with an additional variable speed compressor and an additional condenser disposed along the additional refrigerant loop, wherein the additional variable speed compressor is configured to circulate an additional refrigerant through the additional refrigerant loop, and wherein the additional refrigerant is configured to flow into the evaporator and to absorb heat from the coolant.

12 . The refrigeration system of claim 1 , wherein the fan is a variable speed fan.

13 . A refrigeration system controller, comprising:
a memory configured to store instructions for operating a free-cooling system and a mechanical cooling system; a processor configured to execute the instructions, wherein the instructions comprise: determining one or both of a temperature of ambient air and a cooling load demand; operating a fan of an air-cooled heat exchanger at a first speed based at least on one or both of the temperature of ambient air and the cooling load demand; adjusting the first speed of the fan based on changes of at least one or both of the temperature of ambient air and the cooling load demand; and initiating operation of a variable speed compressor of the mechanical cooling system when the first speed reaches a threshold speed, wherein the variable speed compressor is configured to operate at a compressor speed based on one or more of the temperature of ambient air, the cooling load demand, and the first speed of the fan before operating the fan at a maximum speed.

14 . The refrigeration system of claim 13 , wherein the instructions comprise adjusting the first speed of the fan to substantially zero when the temperature of ambient air reaches a threshold temperature.

15 . The refrigeration system of claim 14 , wherein the instructions comprise bypassing the air-cooled heat exchanger when the temperature of ambient air exceeds the threshold temperature.

16 . The refrigeration system of claim 14 , wherein the threshold temperature is less than a temperature of a cooling fluid returning from a load.

17 . The refrigeration system of claim 13 , wherein the threshold speed is a predetermined threshold speed less, than the maximum speed.

18 . The refrigeration system of claim 13 , comprising a temperature sensor configured to monitor the ambient air temperature and to provide the ambient air temperature as feedback to the refrigeration system controller.

19 . The refrigeration system of claim 13 , wherein the instructions comprise adjusting one or both of the first speed of the fan and the compressor speed to achieve the cooling load demand.

20 . The refrigeration system of claim 13 , wherein the instructions comprise maintaining the fan at the threshold speed and adjusting the compressor speed to achieve the desired cooling load demand.

21 . A method, comprising:
determining one or both of a temperature of ambient air and a cooling load demand; operating a fan of an air-cooled heat exchanger at a first speed based at least on one or both of the temperature of ambient air and the cooling load demand; adjusting the first speed of the fan based on changes of at least one or both of the temperature of ambient air and the cooling load demand; and initiating operation of a variable speed compressor of the mechanical cooling system when the first speed reaches a threshold speed, wherein the variable speed compressor is configured to operate at a compressor speed based on one or more of the temperature of ambient air, the cooling load demand, and the first speed of the fan before operating the fan at a maximum speed.

22 . The method of claim 21 , comprising adjusting the first speed of the fan to substantially zero when the temperature of ambient air reaches a threshold temperature.

23 . The method of claim 22 , comprising bypassing the air-cooled heat exchanger when the temperature of ambient air exceeds the threshold temperature.

24 . The method of claim 21 , comprising adjusting an additional compressor speed of an additional variable speed compressor when the cooling load demand reaches a threshold cooling load demand.

25 . The method of claim 21 , comprising adjusting the first speed of the fan while adjusting the compressor speed to achieve the cooling load demand.

Assignees

• Johnson Controls Tech Co

Inventors

• Kopko William L

Classifications

• F25B25/005 Primary

  using primary and secondary systems · CPC title

• F25B2500/31

  Low ambient temperatures · CPC title

• F25B49/00

  Arrangement or mounting of control or safety devices · CPC title

• F25B2500/29

  High ambient temperatures · CPC title

• F25B2600/0251

  with on-off operation · CPC title