Constant air volume HVAC system with a dehumidification function and discharge air temperature control, an HVAC controller therefor and a method of operation thereof

• US 8,255,087 B2
• Filed: 01/27/2010
• Issued: 08/28/2012
• Est. Priority Date: 05/21/2009
• Status: Active Grant

• Current Assignee: Lennox Industries Incorporated (Lennox International Incorporated)
• Original Assignee: Lennox Industries Incorporated (Lennox International Incorporated)
• Inventors: Bennett, Alan E., Hess, Mark D., Walter, Stephen A.
• Primary Examiner(s): JARRETT, RYAN A
• Application Number:
  US12/694,473
• Publication Number:
  US 20100298987A1
• Time in Patent Office: 944 Days
• Field of Search: 700/276, 700/278
• US Class Current: 700/278
• 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 11/50 characterised by user interfaces or communication
• CPC Class Codes: F24F 11/58 using Internet communication
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 11/88 Electrical aspects, e.g. circuits
• CPC Class Codes: G01D 4/00 Tariff metering apparatus in taximeters G07B13/00; apparatus actuated by coins, cards or the like with meter-controlled dispensing of liquid, gas, or electricity G07F15/00
• CPC Class Codes: G01R 21/00 Arrangements for measuring electric power or power factor G01R7/12 takes precedence
• CPC Class Codes: G01R 21/127 by using pulse modulation G01R21/133 takes precedence
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 21/1335 Tariff switching circuits
• CPC Class Codes: G05B 13/00 Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion G05B19/00 takes precedence
• CPC Class Codes: G05B 13/02 electric
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence
• CPC Class Codes: G05B 2219/2614 HVAC, heating, ventillation, climate control
• CPC Class Codes: G05D 23/1393 characterised by the use of electric means
• CPC Class Codes: G06Q 50/06 Energy or water supply
• CPC Class Codes: H01R 12/00 Structural associations of a plurality of mutually-insulated electrical connecting elements, specially adapted for printed circuits, e.g. printed circuit boards [PCB], flat or ribbon cables, or like generally planar structures, e.g. terminal strips, terminal blocks; Coupling devices specially adapted for printed circuits, flat or ribbon cables, or like generally planar structures; Terminals specially adapted for contact with, or insertion into, printed circuits, flat or ribbon cables, or like generally planar structures printed connections to, or between, printed circuits H05K1/11
• CPC Class Codes: H01R 13/6456 comprising keying elements at different positions along the periphery of the connector
• CPC Class Codes: H02J 2310/14 : The load or loads being home appliances
• CPC Class Codes: H02J 2310/64 : The condition being economic, e.g. tariff based load management
• CPC Class Codes: H02P 25/04 : Single phase motors, e.g. capacitor motors
• CPC Class Codes: H04L 41/082 : the condition being updates or upgrades of network functionality
• CPC Class Codes: Y02B 70/30 : Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y02B 70/3225 : Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y02P 80/10 : Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
• CPC Class Codes: Y04S 20/221 : General power management systems
• CPC Class Codes: Y04S 20/222 : Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/242 : Home appliances
• CPC Class Codes: Y04S 20/244 : the home appliances being or involving heating ventilating and air conditioning [HVAC] units
• CPC Class Codes: Y10T 29/49 : Method of mechanical manufacture
• CPC Class Codes: Y10T 29/49117 : Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49147 : Assembling terminal to base
• CPC Class Codes: Y10T 29/4935 : Heat exchanger or boiler making
• CPC Class Codes: Y10T 29/49359 : Cooling apparatus making, e.g., air conditioner, refrigerator
• CPC Class Codes: Y10T 29/49826 : Assembling or joining

Abstract

An HVAC controller, a method of operating a constant air volume (CAV) HVAC unit and a CAV HVAC system are disclosed herein. In one embodiment, the HVAC controller includes: (1) an interface configured to receive both a latent cooling demand and a sensible cooling demand and (2) a processor configured to direct both a dehumidification function and a discharge air temperature control function for a CAV HVAC system employing the latent cooling demand and the sensible cooling demand.

Claims

1. A heating, ventilating and air conditioning (HVAC) controller, comprising:

an interface configured to receive both a latent cooling demand and a sensible cooling demand; and

a processor configured to simultaneously process said latent cooling demand and said sensible cooling demand and direct both a dehumidification function and a discharge air temperature control function for a constant air volume (CAV) HVAC system employing said latent cooling demand and said sensible cooling demand, said processor configured to calculate a cooling sum by summing a number of cooling stages of said CAV HVAC system having a corresponding reheat coil with a number of cooling stages required to maintain a discharge air temperature of said CAV HVAC system.

2. The HVAC controller as recited in claim 1 wherein said processor if further configured to determine if said cooling sum is less than or equal to a number of compressors installed in said CAV HVAC system.

3. The HVAC controller as recited in claim 2 wherein said processor is configured to activate each reheat coil of said CAV HVAC system and activate a number of compressors of said CAV HVAC system equivalent to a value of said cooling sum when determining said cooling sum is less than or equal to a number of compressors installed in said CAV HVAC system.

4. The HVAC controller as recited in claim 2 wherein said processor is configured to have each reheat coil of said CAV HVAC system deactivated and each of said compressors activated when determining said cooling sum is greater than said number of compressors.

5. The HVAC controller as recited in claim 4 wherein said processor is further configured to keep said reheat coils deactivated until a number of compressors activated without reheat is equal to a number of compressors required for said sensible cooling demand.

6. A method of operating a constant air volume (CAV) heating, ventilating and air conditioning (HVAC) unit having compressor and evaporator coils and employing both a discharge air temperature control function and a dehumidification function, said method comprising:

receiving at least one of a latent cooling demand or a sensible cooling demand;

determining if both a latent cooling demand and a sensible cooling demand are being simultaneously processed;

directing both a dehumidification function and a discharge air temperature control function for said CAV HVAC system when simultaneously processing both said latent cooling demand and said sensible cooling demand, wherein said directing includes calculating a cooling sum by summing a number of cooling stages of said CAV HVAC system having a corresponding reheat coil with a number of cooling stages required to maintain a discharge air temperature of said CAV HVAC system; and

activating said compressor and evaporator coils of said HVAC unit having corresponding reheat coils in response to said latent cooling demand if said latent cooling demand has been received and said sensible cooling demand has not been received.

7. The method as recited in claim 6 further comprising sequentially activating said compressor and evaporator coils based on a discharge air temperature of said CAV HVAC system if said latent cooling demand has not been received and said sensible cooling demand has been received.

8. The method as recited in claim 6 further comprising determining if said cooling sum is less than or equal to a number of compressors installed in said CAV HVAC system.

9. The method as recited in claim 8 further comprising activating each reheat coil of said CAV HVAC system and activate a number of compressors of said CAV HVAC system equivalent to a value of said cooling sum when determining said cooling sum is less than or equal to a number of compressors installed in said CAV HVAC system.

10. The method as recited in claim 8 further comprising deactivating each reheat coil of said CAV HVAC system and activating each of said compressors when determining said cooling sum is greater than said number of compressors.

11. The method as recited in claim 10 further comprising maintaining deactivation of said reheat coils until a number of compressors activated without reheat is equal to a number of compressors required for said sensible cooling demand.

12. A constant air volume (CAV) heating, ventilating and air conditioning (HVAC) system, comprising:

compressor and evaporator coils;

reheat coils corresponding to at least one of said compressor and evaporator coils;

an air blower configured to move air across said compressor and evaporator coils and said reheat coils; and

a controller configured to direct operation of said compressor and evaporator coils, said reheat coils and said air blower, comprising;

an interface configured to receive both a latent cooling demand and a sensible cooling demand for said CAV HVAC system; and

a processor configured to simultaneously process said latent cooling demand and said sensible cooling demand and direct both a dehumidification function and a discharge air temperature control function for said CAV HVAC system employing said latent cooling demand and said sensible cooling demand, wherein said processor is configured to calculate a cooling sum by adding a number of cooling stages of said CAV HVAC system having a corresponding reheat coil with a number of cooling stages required to maintain a discharge air temperature of said CAV HVAC system.

13. The CAV HVAC system as recited in claim 12 wherein said processor if further configured to determine if said cooling sum is less than or equal to a number of compressors installed in said CAV HVAC system.

14. The CAV HVAC system as recited in claim 13 wherein said processor is configured to activate each reheat coil of said CAV HVAC system and activate a number of compressors of said CAV HVAC system equivalent to a value of said cooling sum when determining said cooling sum is less than or equal to a number of compressors installed in said CAV HVAC system.

15. The CAV HVAC system as recited in claim 13 wherein said processor is configured to have each reheat coil of said CAV HVAC system deactivated and each of said compressors activated when determining said cooling sum is greater than said number of compressors.

16. The CAV HVAC system as recited in claim 15 wherein said processor is further configured to keep said reheat coils deactivated until a number of compressors activated without reheat is equal to a number of compressors required for said sensible cooling demand.