Method and apparatus for control of cooling system air quality and energy consumption

• US 20100082161A1
• Filed: 09/24/2009
• Published: 04/01/2010
• Est. Priority Date: 06/17/2008
• Status: Active Grant

• Current Assignee: Ronald Harrison Patch
• Original Assignee: Ronald Harrison Patch
• Inventors: Patch, Ronald Harrison
• Granted Patent: US 8,651,391 B2
• Time in Patent Office: Days
• US Class Current: 700/276
• CPC Class Codes: F24F 11/0001 for ventilation F24F11/30 takes precedence
• 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 11/77 by controlling the speed of ventilators
• CPC Class Codes: F24F 2110/50 Air quality properties
• CPC Class Codes: F24F 2110/70 Carbon dioxide
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

An energy saving air quality control system modulates supply fan speed by use of controlled, variable-frequency drive controls for automatic dampers or suction pressure to maintain adequate air flow across the evaporator coil at partial cooling loads. Indexing the fan speed to maintain the suction pressure of the energized coil controls the maximum relative humidity of the conditioned space. Demand ventilation in the system balances air quality and energy consumption by controlling the outdoor air damper in response to indoor CO₂ and humidity levels. The control system variously either (1) produces a variable 0-10 VDC output signal to modulate the outside ventilation air damper as required to keep the CO₂ and humidity concentration below a set point; (2) produces a 0 or 24 VAC signal to either open or close a two-position outside air damper for as long a time period as is required in order to keep the CO₂ concentration and humidity below a set point; or (3) allows manually setting the outside air damper to provide proper ventilation air at maximum occupancy and maximum air flow and modulates the supply fan speed as required to keep the CO₂ concentration and humidity level as measured by a CO₂ monitor and leaving air dewpoint temperature below set point.

Claims

1. A retrofit control system for controlling the speed of a fan motor for a forced air flow air conditioning system operable in heating, ventilation, deadband, and part load cooling modes to control supply air speed during operation of said air conditioning system to reduce energy consumption, and provide humidity and CO₂ air quality control, said control system comprising:

(a) a suction pressure/temperature sensor located on a suction refrigerant line exiting a direct expansion cooling coil;

(b) a control mode input relay digital input circuit;

(c) a power output circuit for controlling the speed of said fan motor in accordance with a control mode input signal;

(d) a CO₂ analog sensor in either the conditioned space or in the return air stream;

(e) a heating operation and cooling operation selection circuit operably connected to said power output circuit and input relay circuit and suction pressure/temperature sensor for varying the air flow in each of the cooling, heating, ventilation and deadband modes, controlling refrigerant suction pressure, and modulating the ventilation rate as required to maintain a maximum of 1000 ppm of CO₂. and a preset coil discharge air dewpoint temperature.

2. The control system of claim 1, wherein said control system is preprogrammed to match a specific brand and model of air conditioning system based on the cooling and heating capacity of said system.

3. The control system of claim 1, wherein the heating operation and cooling operation selection circuit produces a variable 0-10 VDC output signal to modulate the ventilation air damper as required to keep the CO₂ concentration as measured by a CO₂ monitor below set point.

4. The control system of claim 1, wherein the heating operation and cooling operation selection circuit produces a 0 or 24 VAC signal to either open or close a two-position outside air damper for as long a time period as required to keep the CO₂ concentration as measured by a CO₂ monitor below set point.

5. The control system of claim 1, wherein the outside air damper is manually set to provide proper ventilation air at maximum occupancy and maximum air flow and modulates the supply fan speed as required to keep the CO₂ concentration, as measured by a CO₂ monitor, below set point.

6. The control system of claim 1, wherein the speed of the supply fan is slowly accelerated.

7. A method of controlling the speed of a fan motor for a forced air flow air conditioning system operable in heating, ventilation, deadband, and part load cooling modes, respectively, to control supply air fan speed during operation of said air conditioning system to reduce energy consumption, and provide humidity and CO₂ air quality control, said method comprising:

(a) employing a suction pressure/temperature sensor analog input circuit located on a suction refrigerant line exiting a direct expansion cooling coil;

(b) employing a control mode input relay digital input circuit;

(c) employing a power output circuit for controlling the speed of said motor as a function of said output signal to vary the speed of said motor in accordance with a control mode input signal;

(d) employing a CO₂ analog sensor in either the conditioned space or in the return air stream; and

(e) employing a heating operation and cooling operation selection circuit operably connected to said power output circuit and said input relay circuit and suction pressure/temperature sensor for varying the air flow in each of the cooling, heating, ventilation and deadband modes, controlling refrigerant suction pressure, and modulating the ventilation rate as required to maintain a maximum of 1000 ppm of CO₂ and a set coil discharge air dewpoint temperature.

8. The method of claim 7, wherein the heating operation and cooling operation selection circuit produces a variable 0-10 VDC output signal to modulate the ventilation air damper as required to keep the CO) concentration, as measured by a CO₂ monitor, below set point.

9. The method of claim 7, wherein the heating operation and cooling operation selection circuit produces a 0 or 24 VAC signal to either open or close a two-portion outside air damper for as long a time period as required to keep the CO₂ concentration, as measured by a CO₂ monitor, below set point.

10. The method of claim 7, wherein the outside air damper is manually set to provide proper ventilation air at maximum occupancy and maximum air flow and modulates the supply fan speed as required to keep the CO2 concentration, as measured by a CO2 monitor, below set point.

11. The method of claim 7, wherein the speed of the supply fan is slowly accelerated.

12. A process of controlling the speed of a fan motor for a forced air flow air conditioning system for a space wherein fan speed is indexed to maintain a preset maximum relative humidity level in the space.

13. A process of controlling the speed of a fan motor for a forced air flow air conditioning system for space wherein fan speed is controlled to vary air flow in heating, ventilation, deadband, and part load cooling modes such that energy consumption is reduced.

14. A process of controlling the speed of a fan motor for a forced air flow air conditioning system for a space wherein fan speed is indexed to maintain a preset maximum CO₂ level in the space such that CO₂ air quality is maintained at a preset maximum value of CO₂ concentration.

15. A process of controlling the speed of a fan motor for a forced air flow air conditioning system for space wherein fan speed is indexed to maintain a preset maximum relative humidity level in the space such that energy consumption is reduced and maximum CO₂ levels and relative humidity are maintained.

16. The process of claim 15, wherein:

(a) a suction pressure/temperature sensor analog input circuit is located on a suction refrigerant line exiting a direct expansion cooling coil;

(b) a control mode input relay digital input circuit produces a signal based on the suction pressure or temperature data;

(c) a power output circuit produces a signal and controls the speed of said motor as a function of said output signal to vary the speed of said motor in accordance with said control mode input signal;

(d) a CO₂ analog sensor in either the conditioned space or in the return air stream senses the CO₂ levels in the space on air stream; and

(e) a cooling operation selection circuit is operably connected to said power output circuit, said input relay circuit, and said suction pressure/temperature sensor for varying the air flow in each of the cooling, ventilation and deadband modes, and modulating the ventilation rate as required to maintain a preset maximum level of CO₂ and a set coil discharge air dewpoint temperature; and

(f) an evaporator face damper on the de-energized coil section prevents air bypass through the de-energized coil face at partial cooling loads.

17. The control system of claim 16, wherein said control system is preprogrammed to match a specific brand and model of air conditioning system based on the cooling and heating capacity of said air conditioning system.

18. The control system of claim 16, wherein the heating operation and cooling operation selection circuit produces a variable 0-10 VDC output signal to modulate the ventilation air damper as required to keep the CO₂ concentration as measured by a CO₂ monitor below set point.

19. The control system of claim 16, wherein the heating operation and cooling operation selection circuit produces a 0 or 24 VAC signal to either open or close a two-position outside air damper for as long a time period as required to keep the CO₂ concentration as measured by a CO₂ monitor below set point.

20. The control system of claim 16, wherein the outside air damper is manually set to provide proper ventilation air at maximum occupancy and maximum air flow and modulates the supply fan speed as required to keep the CO₂ concentration, as measured by a CO₂ monitor, below set point.

21. The control system of claim 16, wherein the speed of the supply fan is slowly accelerated.

22. A method of controlling the speed of a fan motor for a forced air flow air conditioning system operable in ventilation, deadband, and part load cooling modes, respectively, to control supply air fan speed during operation of said air conditioning system, said method comprising:

(a) sensing suction pressure or temperature on a suction refrigerant line exiting a direct expansion cooling coil;

(b) inputting said pressure or temperature data into a control mode input relay digital input circuit;

(c) controlling the speed of said motor through a power output circuit to vary the speed of said motor in accordance with a control mode input signal;

(d) employing a CO₂ analog sensor in either the conditioned space or in the return air stream; and

(e) employing a cooling operation selection circuit operably connected to said power output circuit, said input relay circuit, and said suction pressure/temperature sensor for varying the air flow in each of the cooling, ventilation, and deadband modes, controlling refrigerant suction pressure, and modulating the ventilation rate, as required to maintain a maximum set concentration of CO₂ and a set coil discharge air dewpoint temperature.

23. The method of claim 22, wherein the cooling operation selection circuit produces a variable 0-10 VDC output signal to modulate the ventilation air damper as required to keep the CO₂ concentration, as measured by a CO₂ monitor, below set point.

24. The method of claim 22, wherein the cooling operation selection circuit produces a 0 or 24 VAC signal to either open or close a two-portion outside air damper for as long a time period as required to keep the CO₂ concentration, as measured by a CO₂ monitor, below set point.

25. The method of claim 22, wherein the outside air damper is manually set to provide proper ventilation air at maximum occupancy and maximum air flow and modulates the supply fan speed as required to keep the CO₂ concentration, as measured by a CO₂ monitor, below set point.

26. The method of claim 22, wherein the speed of the supply fan is slowly accelerated.

27. A process of controlling the speed of a fan motor for a forced air flow air conditioning system for a space wherein fan speed is indexed to maintain a preset maximum relative humidity level in the space.

28. A process of controlling the speed of a fan motor for a forced air flow air conditioning system for space wherein fan speed is controlled to vary air flow in heating, ventilation, deadband, and part load cooling modes such that energy consumption is reduced.

29. A process of controlling the speed of a fan motor for a forced air flow air conditioning system for space wherein fan speed is indexed to maintain a preset maximum relative CO₂ level in the space such that CO₂ air quality is maintained at a maximum CO₂ concentration.

30. A retrofit control system for controlling the speed of a fan motor for a forced air flow air conditioning system operable in heating, ventilation, deadband, and part load cooling modes to control supply air speed during operation of said air conditioning system to reduce energy consumption, and provide humidity and CO₂ air quality control, said control system comprising:

(a) a suction pressure/temperature sensor located on a suction refrigerant line exiting a direct expansion cooling coil;

(b) a control mode input relay digital input circuit;

(c) a power output circuit for controlling the speed of said fan motor in accordance with a control mode input signal;

(d) a CO₂ analog sensor in either the conditioned space or in the return air stream;

(e) a heating operation and cooling operation selection circuit operably connected to said power output circuit and input relay circuit and suction pressure/temperature sensor for varying the air flow in each of the cooling, heating, ventilation and deadband modes, controlling refrigerant suction pressure, and modulating the ventilation rate as required to maintain a maximum of 1000 ppm of CO₂ and a preset coil discharge air dewpoint temperature; and

(f) preprogramming to match the retrofit control system with a specific brand and model of air conditioning system based on the cooling and heating capability of said system;

wherein said heating operation and cooling operation selection circuit produces a variable 0-10 VDC output signal to modulate the ventilation air damper as required to keep the CO₂ concentration as measured by a CO₂ monitor below set point, and the speed of the supply fan is slowly accelerated.

31. A retrofit control system for controlling the speed of a fan motor for a forced air flow air conditioning system operable in heating, ventilation, deadband, and part load cooling modes to control supply air speed during operation of said air conditioning system to reduce energy consumption, and provide humidity and CO₂ air quality control, said control system comprising:

(a) a suction pressure/temperature sensor located on a suction refrigerant line exiting a direct expansion cooling coil;

(b) a control mode input relay digital input circuit;

(c) a power output circuit for controlling the speed of said fan motor in accordance with a control mode input signal;

(d) a CO₂ analog sensor in either the conditioned space or in the return air stream;

(e) a heating operation and cooling operation selection circuit operably connected to said power output circuit and input relay circuit and suction pressure/temperature sensor for varying the air flow in each of the cooling, heating, ventilation and deadband modes, controlling refrigerant suction pressure, and modulating the ventilation rate as required to maintain a maximum of 1000 ppm of CO₂ and a preset coil discharge air dewpoint temperature; and

(f) preprogramming to match the retrofit control system with a specific brand and model of air conditioning system based on the cooling and heating capacity of said system;

wherein the outside air damper is manually set to provide proper ventilation air at maximum occupancy and maximum air flow and modulates the supply fan speed as required to keep the CO₂ concentration, as measured by a CO₂ monitor, below set point, and the speed of the supply fan is slowly accelerated.