Control system for operating condenser fans
View Patent ↗Methods and systems for controlling the operation of condenser fans are provided. At most discharge pressures, the operation of the condenser fans may be controlled based on a capacity of the compressor system. To adjust operation of the condenser fans, the speed of the fans and/or the number or operational fans may be adjusted. The control of the condenser fans based on compressor system capacity may be overridden at compressor discharge pressures that rise above a high pressure level and fall below a low pressure level. At the high and low discharge pressures, the fan speed and/or number of operating fans may be adjusted based solely on the discharge pressure rather than on the compressor system capacity.
1. A refrigeration system comprising:
a variable capacity compressor system configured to compress refrigerant;
a condenser configured to receive and to condense the compressed refrigerant;
an expansion device configured to expand the condensed refrigerant;
an evaporator configured to evaporate the expanded refrigerant prior to returning the refrigerant to the variable capacity compressor system;
one or more fans driven by a fan drive and configured to displace air over the condenser;
a means for determining a discharge pressure of the variable capacity compressor system; and
a controller operatively coupled to the fan drive and configured to:
regulate the fan drive based on an operational capacity of the variable capacity compressor system when the discharge pressure is within a range defined by a first level and a second level,
regulate the fan drive based on the discharge pressure when the discharge pressure is below the first level or above the second level,
reduce fan speed of the fan drive based on the discharge pressure when the discharge pressure is below the first level,
deactivate the variable capacity compressor system when the discharge pressure is below a third level, wherein the third level is below the first level,
increase fan speed of the fan drive when the discharge pressure is above the second level, and
interrupt operation of the variable capacity compressor system when the discharge pressure is above a fourth level, wherein the fourth level is above the second level.
2. The refrigeration system of claim 1 , wherein the means for determining a discharge pressure comprises a pressure sensor configured to detect the discharge pressure.
3. The refrigeration system of claim 1 , wherein the operational capacity comprises a total operational displacement rate of refrigerant through the compressor system.
4. The refrigeration system of claim 1 , wherein the controller is configured to regulate the fan drive independent of the operational capacity when the discharge pressure is below the first level or above the second level.
5. The refrigeration system of claim 1 , wherein the operational capacity represents a desired operational capacity, and wherein the controller is configured to determine the desired operational capacity based on a load on the refrigeration system.
6. The refrigeration system of claim 5 , wherein the controller is configured to adjust operation of the variable capacity compressor system to operate the variable capacity compressor system at the desired operational capacity.
7. The refrigeration system of claim 1 , comprising another controller configured to determine the operational capacity based on a load on the refrigeration system and to provide the operational capacity to the controller operatively coupled to fan drive.
8. The refrigeration system of claim 1 , comprising one or more sensors configured to measure operational parameters of the variable capacity compressor system, wherein the controller is configured to determine the operational capacity using the measured operational parameters.
9. The refrigeration system of claim 1 , wherein the measured operational parameters comprise a compressor rotational speed, or a number of operational compressors, or a combination thereof.
10. A refrigeration system comprising:
a variable capacity compressor system of one or more variable speed compressors configured to compress refrigerant;
a condenser configured to receive and to condense the compressed refrigerant;
an expansion device configured to expand the condensed refrigerant;
an evaporator configured to evaporate the expanded refrigerant prior to returning the refrigerant to the variable capacity compressor system;
one or more fans driven by a fan drive and configured to displace air over the condenser;
a means for determining a discharge pressure of the variable capacity compressor system; and
a controller operatively coupled to fan drive and configured to:
regulate the fan drive based on a rotational speed of the one or more variable speed compressors when the discharge pressure is within a range defined by a first level and a second level,
regulate the fan drive based on the discharge pressure when the discharge pressure is below the first level or above the second level,
reduce fan speed based on the discharge pressure when the discharge pressure is below the first level,
deactivate the variable capacity compressor system when the discharge pressure is below a third level, wherein the third level is below the first level,
increase fan speed when the discharge pressure is above the second level, and
interrupt operation of the variable capacity compressor system when the discharge pressure is above a fourth level, wherein the fourth level is above the second level.
11. The refrigeration system of claim 10 , wherein the controller is configured to regulate the fan drive to drive the one or more fans at speeds that are proportional to the rotational speed of the one or more compressors.
12. The refrigeration system of claim 10 , wherein the controller is configured to regulate the fan drive by varying fan speed of the one or more fans.
13. The refrigeration system of claim 10 , comprising two or more fans, wherein the controller is configured to regulate the fan drive by selectively enabling and disabling operation of the two or more fans.
14. The refrigeration system of claim 10 , wherein the rotational speed represents a desired rotational speed, and wherein the controller is configured to determine the desired rotational speed based on a load on the refrigeration system.
15. A method of operating a refrigeration system, the method comprising:
determining an operational capacity of a compressor system;
determining a discharge pressure of the compressor system;
controlling operation of one or more condenser fans based on the operational capacity when the discharge pressure is within a range defined by a first level and a second level;
controlling operation of the one or more condenser fans based on the discharge pressure when the discharge pressure is below the first level or above the second level,
increasing a fan speed of the one or more condenser fans when the discharge pressure is above the second level;
decreasing the fan speed of the one or more condenser fans when the discharge pressure is below the first level;
deactivating the compressor system when the discharge pressure is below a third level, wherein the third level is below the first level; and
interrupting operation of the compressor system when the discharge pressure is above a fourth level, wherein the fourth level is above the second level.
16. The method of claim 15 , wherein determining an operational capacity comprises determining a desired operational capacity based on a load on the refrigeration system.
17. The method of claim 16 , wherein determining a desired operational capacity comprises determining a rotational compressor speed for producing the desired operational capacity.
18. The method of claim 16 , wherein determining a desired operational capacity comprises determining an operational number of compressors for producing the desired operational capacity.
19. The method of claim 15 , wherein controlling operation of one or more condenser fans based on the operational capacity when the discharge pressure is within a range defined by a first level and a second level comprises linearly varying a fan speed based on a rotational speed of one or more compressors within the compressor system.