Retrofitting a constant volume air handling unit with a variable frequency drive

• US 9,400,119 B2
• Filed: 01/05/2015
• Issued: 07/26/2016
• Est. Priority Date: 03/19/2008
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Inventors: Malloy, Ronald M.
• Primary Examiner(s): Flanigan, Allen
• Assistant Examiner(s): Zec, Filip
• Application Number:
  US14/589,459
• Publication Number:
  US 20150120064A1
• Time in Patent Office: 568 Days
• Field of Search: 236/46.R
• US Class Current: 1/1
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/46 Improving electric energy efficiency or saving
• CPC Class Codes: F24F 11/58 using Internet communication
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: F24F 11/81 by controlling the air supply to heat-exchangers or bypass channels
• CPC Class Codes: F24F 2110/00 Control inputs relating to air properties
• CPC Class Codes: F24F 2110/50 Air quality properties
• CPC Class Codes: F24F 2110/70 Carbon dioxide
• CPC Class Codes: F24F 2120/10 Occupancy
• CPC Class Codes: F24F 3/044 Systems in which all treatment is given in the central station, i.e. all-air systems
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: Y02B 30/00 Energy efficient heating, ventilation or air conditioning [HVAC]
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
• CPC Class Codes: Y02B 30/90 Passive houses; Double facade technology

Abstract

A system and methods providing real-time monitoring, management and control of a variable frequency drive retrofit to a constant volume air handling unit without making significant mechanical or control system changes. Customers and vendors are provided with a more informative and economically attractive air handling unit. The system also provides a finer granularity of control over conditioned air properties such as temperature, humidity and air quality.

Claims

1. A system comprising:

a processor; and

a memory communicatively coupled to the processor, the memory having stored therein computer-executable instructions, comprising;

a controller component configured to;

determine a temperature difference between an intake air temperature at an entrance of a heat exchange area of a constant volume air handling unit and a discharge air temperature at an exit of the heat exchange area of the constant volume air handling unit;

determine an angular velocity for a blower based at least upon the determined temperature difference to achieve a predetermined heating or cooling demand for a conditioned space; and

set at least one parameter of a variable frequency drive to cause the blower to achieve the determined angular velocity.

2. The system of claim 1, wherein the controller is further configured to determine the angular velocity based at least upon an air quality parameter associated with the conditioned space.

3. The system of claim 1, wherein the controller is further configured to determine the angular velocity based at least upon a motion parameter associated with the conditioned space.

4. The system of claim 1, wherein the controller is further configured to determine the angular velocity based at least upon a damper parameter associated with a position of an outside air damper.

5. The system of claim 4, wherein the controller is further configured to instruct a damper switch to set the outside air damper to a first position determined based upon at least one of the damper parameter, the intake air temperature, the discharge air temperature, an air quality parameter, or a motion parameter.

6. The system of claim 1, wherein the controller is further configured to:

determine whether the discharge air temperature has reached a first temperature indicative of a cooling coil in the constant volume air handling unit beginning to freeze; and

in response to the discharge air temperature reaching the first temperature, increase the angular velocity.

7. The system of claim 1, wherein the controller is further configured to:

determine whether the discharge air temperature has reached a second temperature indicative of a heating coil in the constant volume air handling unit beginning to overheat; and

in response to the discharge air temperature reaching the second temperature, increases the angular velocity.

8. The system of claim 1, wherein the controller is further configured to determine an actual cost savings based upon an actual cost of the system for a historical period of time for a plurality of determined angular velocities as compared to an estimated cost for the historical period of time at a constant angular velocity.

9. The system of claim 1, wherein the controller is further configured to determine a predicted costs savings based upon a predicted cost of the system for a future period of time for a plurality of determined angular velocities as compared to an estimated cost for the future period of time at a constant angular velocity.

10. A method comprising:

determining, by a system including a processor, an intake air temperature of air at an entrance of a heat exchange area of a constant volume air handling unit;

determining, by the system, a discharge air temperature of air at an exit of the heat exchange area of the constant volume air handling unit;

determining, by the system, a temperature difference between the intake air temperature and the discharge air temperature;

determining, by the system, an angular velocity for a blower based at least upon the determined temperature difference to achieve a predetermined heating or cooling demand for a conditioned space; and

setting, by the system, at least one parameter of the variable frequency drive to cause the blower to achieve the determined angular velocity.

11. The method of claim 10, further comprising determining, by the system, the angular velocity based at least upon an air quality parameter associated with the conditioned space.

12. The method of claim 10, further comprising determining, by the system, the angular velocity based at least upon a motion parameter associated with the conditioned space.

13. The system of claim 10, further comprising determining, by the system, the angular velocity based at least upon a damper parameter associated with a position of an outside air damper.

14. The method of claim 10, further comprising:

determining, by the system, whether the discharge air temperature has reached a first temperature indicative of a cooling coil in the constant volume air handling unit beginning to freeze; and

in response to the discharge air temperature reaching the first temperature, increasing, by the system, the angular velocity.

15. The method of claim 10, further comprising:

determining, by the system, whether the discharge air temperature has reached a second temperature indicative of a heating coil in the constant volume air handling unit beginning to overheat; and

in response to the discharge air temperature reaching the second temperature, increasing, by the system, the angular velocity.

16. The method of claim 10, further comprising determining, by the system, a predicted costs savings based upon a predicted cost of the method for a future period of time for a plurality of determined angular velocities as compared to an estimated cost for the future period of time at a constant angular velocity.

17. A non-transitory computer-readable medium having instructions stored thereon that, in response to execution, cause at least one device including a processor to perform operations comprising:

determining an upstream intake air temperature of air at an entrance of a heat exchange area of a constant volume air handling unit;

determining a discharge air temperature of air at an exit of the heat exchange area of the constant volume air handling unit;

determining a temperature difference between the intake air temperature and the discharge air temperature;

determining an angular velocity for a blower based at least upon the determined temperature difference to achieve a predetermined heating or cooling demand for a conditioned space; and

setting at least one parameter of the variable frequency drive to cause the blower to achieve the determined angular velocity.

18. The system of claim 17, the operations further comprising:

determining whether the discharge air temperature has reached a first temperature indicative of a cooling coil in the constant volume air handling unit beginning to freeze; and

in response to the discharge air temperature reaching the first temperature, increasing the angular velocity.

19. The system of claim 17, the operations further comprising:

determining whether the discharge air temperature has reached a second temperature indicative of a heating coil in the constant volume air handling unit beginning to overheat; and

in response to the discharge air temperature reaching the second temperature, increasing the angular velocity.

20. The system of claim 17, the operations further comprising determining a predicted costs savings based upon a predicted cost of the method for a future period of time for a plurality of determined angular velocities as compared to an estimated cost for the future period of time at a constant angular velocity.