Controls for air conditioner

• US 6,792,767 B1
• Filed: 10/21/2002
• Issued: 09/21/2004
• Est. Priority Date: 10/21/2002
• Status: Active Grant

• Current Assignee: AAON Incorporated
• Original Assignee: AAON Incorporated
• Inventors: Pargeter, Stephen J., Knebel, David
• Primary Examiner(s): Norman, Marc
• Application Number:
  US10/274,778
• Time in Patent Office: 701 Days
• Field of Search: 621/73, 621/766, 62/90, 621/86, 622/285, 622/29, 621/763, 236/44.C
• US Class Current: 62/173
• 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 11/62 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 2110/00 Control inputs relating to air properties
• CPC Class Codes: F24F 2110/20 Humidity
• CPC Class Codes: F24F 2110/30 Velocity
• CPC Class Codes: F24F 3/153 with subsequent heating, i.e. with the air, given the required humidity in the central station, passing a heating element to achieve the required temperature
• CPC Class Codes: F25B 2600/0253 with variable speed
• CPC Class Codes: F25B 2700/1933 Suction pressures
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A control system for a HVAC unit for controlling the humidity and temperature of interior building space at desired levels regardless of the outside temperature and humidity conditions. This system is more efficiently so that it operates with less energy consumption than current HVAC systems. The control system employs a combination of modulated return air bypass, modulated capacity compressor, and modulating hot gas reheat to maintain proper interior space humidity, and temperature while maintaining adequate ventilation within the interior building space. The system employs feed forward control to prevent overheating the interior building space with reheat and also, once humidity requirements are met, resets low pressure limit settings at the exit of the evaporator to minimize use of reheat in the operation of the unit.

Claims

1. Controls for an air conditioner comprising:

a modulated capacity compressor for pumping varying amounts of coolant through a coolant circuit of an air conditioner,

modulated return air bypass damper for varying the amount of return air bypassing an evaporator of the air conditioner,

a modulated reheater provided adjacent the evaporator for adding reheat to an air stream after the air stream passes through the evaporator,

a controller attached to and controlling modulation of the compressor, said controller attached to and controlling the return air bypass damper, and said controller attached to and controlling modulation of a valve that modulates the reheater,

said controller attached to and receiving information from a temperature sensor that senses air temperature of conditioned space air produced by the air conditioner, said controller controlling modulation of the compressor to maintain a desired temperature in the conditioned space air, and

said controller attached to and receiving information from a humidity sensor that senses air humidity of conditioned space air produced by the air conditioner, and said controller first modulating the return air bypass damper to maintain a desired humidity in the conditioned space air and then said controller second also modulating the reheat valve to control flow of hot coolant gas to the reheater to maintain the desired humidity in the conditioned space air.

2. Controls for an air conditioner comprising:

a modulated capacity compressor for pumping varying amounts of coolant through a coolant circuit of an air conditioner,

modulated return air bypass damper for varying the amount of return air bypassing an evaporator of the air conditioner,

a modulated reheater provided adjacent the evaporator for adding reheat to an air stream after the air stream passes through the evaporator,

a controller attached to and controlling modulation of the compressor, said controller attached to and controlling the return air bypass damper, said controller attached to and controlling modulation of a valve that modulates the reheater,

said controller attached to and receiving information from a temperature sensor that senses air temperature of conditioned space air produced by the air conditioner, said controller controlling modulation of the compressor to maintain a desired temperature in the conditioned space air,

said controller attached to and receiving information from a humidity sensor that senses air humidity of conditioned space air produced by the air conditioner, and said controller first modulating the return air bypass damper to maintain a desired humidity in the conditioned space air and then said controller second also modulating the reheat valve to control flow of hot coolant gas to the reheater to maintain the desired humidity in the conditioned space air,

an air intake sensor for sensing flow of outside air intake provided at an outside air intake damper of the air conditioner, said controller attached to and receiving outside air intake flow information from said air intake sensor, and said controller operating the outside air damper and a return air damper provided on the return air line of the air conditioner to maintain a constant volume of outside air flow through the outside air intake damper.

3. Controls for an air conditioner comprising:

a modulated capacity compressor for pumping varying amounts of coolant through a coolant circuit of an air conditioner,

modulated return air bypass damper for varying the amount of return air bypassing an evaporator of the air conditioner,

a modulated reheater provided adjacent the evaporator for adding reheat to an air stream after the air stream passes through the evaporator,

a controller attached to and controlling modulation of the compressor, said controller attached to and controlling the return air bypass damper, said controller attached to and controlling modulation of a valve that modulates the reheater,

said controller attached to and receiving information from a temperature sensor that senses air temperature of conditioned space air produced by the air conditioner, said controller controlling modulation of the compressor to maintain a desired temperature in the conditioned space air,

said controller attached to and receiving information from a humidity sensor that senses air humidity of conditioned space air produced by the air conditioner, and said controller first modulating the return air bypass damper to maintain a desired humidity in the conditioned space air and then said controller second also modulating the reheat valve to control flow of hot coolant gas to the reheater to maintain the desired humidity in the conditioned space air,

a carbon monoxide sensor for sensing the carbon monoxide level in the conditioned space air, said controller attached to and receiving carbon monoxide level information from said carbon monoxide sensor, and said controller operating the outside air damper and a return air damper provided on the return air line of the air conditioner to maintain adequate outside air flow through the outside air intake damper.

4. Controls for an air conditioner comprising:

a modulated capacity compressor for pumping varying amounts of coolant through a coolant circuit of an air conditioner,

modulated return air bypass damper for varying the amount of return air bypassing an evaporator of the air conditioner,

a modulated reheater provided adjacent the evaporator for adding reheat to an air stream after the air stream passes through the evaporator,

a controller attached to and controlling modulation of the compressor, said controller attached to and controlling the return air bypass damper, said controller attached to and controlling modulation of a valve that modulates the reheater,

said controller attached to and receiving information from a temperature sensor that senses air temperature of conditioned space air produced by the air conditioner, said controller controlling modulation of the compressor to maintain a desired temperature in the conditioned space air,

said controller attached to and receiving information from a humidity sensor that senses air humidity of conditioned space air produced by the air conditioner, and said controller first modulating the return air bypass damper to maintain a desired humidity in the conditioned space air and then said controller second also modulating the reheat valve to control flow of hot coolant gas to the reheater to maintain the desired humidity in the conditioned space air,

a suction pressure sensor provided at a coolant exit from the evaporator for sensing pressure of the evaporator, said controller attached to and receiving pressure information from said suction pressure sensor, and said controller operating the return air bypass damper to maintain pressure at the suction pressure sensor above a predetermined low pressure set point.

5. Controls for an air conditioner according to claim 4 further comprising:

an air intake sensor for sensing flow of outside air intake provided at an outside air intake damper of the air conditioner, said controller attached to and receiving outside air intake flow information from said air intake sensor, and said controller operating the outside air damper and a return air damper provided on the return air line of the air conditioner to maintain a constant volume of outside air flow through the outside air intake damper.

6. Controls for an air conditioner according to claim 5 further comprising:

a supply air temperature sensor provided in a supply air line of the air conditioner, said controller attached to and receiving information from the supply air temperature sensor, and said controller modulating the compressor as a feed-forward control so that the compressor supplies more coolant to the evaporator.

7. Controls for an air conditioner according to claim 5 further comprising:

said controller sensing when a desired humidity has been attained in the conditioned space air and resetting the low pressure limit set point for suction pressure at the suction pressure sensor so that the air conditioner operates most efficiently by minimizing use of reheat.

8. A dynamic control system for controlling the operation of an air conditioner comprising:

a controller attached to and controlling operation of a modulated capacity compressor capable of pumping varying amounts of coolant through a coolant circuit of an air conditioner,

said controller attached to and controlling operation of a return air bypass damper that modulates the amount of return air bypassing the evaporator of the air conditioner,

said controller attached to and controlling modulation of a valve that modulates the reheater that is provided adjacent the evaporator and adds heat to an air stream after the air stream passes through the evaporator,

said controller attached to and receiving information from a temperature sensor that senses air temperature of conditioned space air produced by the air conditioner,

said controller attached to and receiving information from a humidity sensor that senses air humidity of conditioned space air produced by the air conditioner, and

said controller first modulating the return air bypass damper as much as possible to maintain a desired humidity in the conditioned space air, and then said controller second modulating the reheat valve to control flow of hot coolant gas to the reheater to maintain the desired humidity in the conditioned space air.

9. A dynamic control system for controlling the operation of an air conditioner according to claim 8 further comprising:

said controller controlling modulation of the compressor to maintain a desired temperature in the conditioned space air.

10. A dynamic control system for controlling the operation of an air conditioner comprising:

a controller attached to and controlling operation of a modulated capacity compressor capable of pumping varying amounts of coolant through a coolant circuit of an air conditioner,

said controller attached to and controlling operation of a return air bypass damper that modulates the amount of return air bypassing the evaporator of the air conditioner,

said controller attached to and controlling modulation of a valve that modulates the reheater that is provided adjacent the evaporator and adds heat to an air stream after the air stream passes through the evaporator,

said controller attached to and receiving information from a temperature sensor that senses air temperature of conditioned space air produced by the air conditioner,

said controller attached to and receiving information from a humidity sensor that senses air humidity of conditioned space air produced by the air conditioner,

said controller first modulating the return air bypass damper as much as possible to maintain a desired humidity in the conditioned space air, and then said controller second modulating the reheat valve to control flow of hot coolant gas to the reheater to maintain the desired humidity in the conditioned space air,

said controller controlling modulation of the compressor to maintain a desired temperature in the conditioned space air,

a suction pressure sensor provided at a coolant exit from the evaporator for sensing pressure of the evaporator, said controller attached to and receiving pressure information from said suction pressure sensor, and said controller operating the return air bypass damper to maintain pressure at the suction pressure sensor above a predetermined low pressure set point.

11. A dynamic control system for controlling the operation of an air conditioner according to claim 10 further comprising:

an air intake sensor for sensing flow of outside air intake provided at an outside air intake damper of the air conditioner, said controller attached to and receiving outside air intake flow information from said air intake sensor, and said controller operating the outside air damper and a return air damper provided on the return air line of the air conditioner to maintain a constant volume of outside air flow through the outside air intake damper.

12. A dynamic control system for controlling the operation of an air conditioner according to claim 11 further comprising:

an air intake sensor for sensing flow of outside air intake provided at an outside air intake damper of the air conditioner, said controller attached to and receiving outside air intake flow information from said air intake sensor, and said controller operating the outside air damper and a return air damper provided on the return air line of the air conditioner to maintain a constant volume of outside air flow through the outside air intake damper.

13. A dynamic control system for controlling the operation of an air conditioner according to claim 12 further comprising:

a supply air temperature sensor provided in a supply air line of the air conditioner, said controller attached to and receiving information from the supply air temperature sensor, and said controller modulating the compressor as a feed-forward control so that the compressor supplies more coolant to the evaporator.

14. A dynamic control system for controlling the operation of an air conditioner according to claim 13 further comprising:

said controller sensing when a desired humidity has been attained in the conditioned space air and resetting the low pressure limit set point for suction pressure at the suction pressure sensor so that the air conditioner operates most efficiently by minimizing use of reheat.

15. Controls for an air conditioner according to claim 10 further comprising:

a carbon monoxide sensor for sensing the carbon monoxide level in the conditioned space air, said controller attached to and receiving carbon monoxide level information from said carbon monoxide sensor, and said controller operating the outside air damper and a return air damper provided on the return air line of the air conditioner to maintain adequate outside air flow through the outside air intake damper.