Space conditioning system with outdoor air and refrigerant heat control of dehumidification of an enclosed space

• US 6,427,461 B1
• Filed: 05/08/2000
• Issued: 08/06/2002
• Est. Priority Date: 05/08/2000
• Status: Expired due to Term

• Current Assignee: Lennox Industries Incorporated (Lennox International Incorporated)
• Original Assignee: Lennox Industries Incorporated (Lennox International Incorporated)
• Inventors: Chapin, Merlin K., Whinery, John S.
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): ROBINSON, DANIEL LEON
• Application Number:
  US09/566,356
• Time in Patent Office: 820 Days
• Field of Search: 621/761, 621/762, 621/763, 621/764, 621/765, 621/766, 621/32, 236/44.A, 236/44.B, 236/44.C, 236/44.R, 236/45, 236/49.1, 165/225
• US Class Current: 62/176.6
• CPC Class Codes: F24F 11/0008 for air-humidification 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 11/65 for selecting an operating mode
• CPC Class Codes: F24F 11/81 by controlling the air supply to heat-exchangers or bypass channels
• CPC Class Codes: F24F 2011/0002 for admittance of outside air
• CPC Class Codes: F24F 2110/20 Humidity
• 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: G05D 27/02 characterised by the use of electric means

Abstract

A space conditioning system for controlling the temperature and humidity of air within an enclosed space includes a vapor compression refrigeration unit having a reheat coil disposed downstream of the system evaporator coil to reheat return air after cooling and condensation of excess water vapor in the return air by the evaporator coil. The system includes a damper for controlling inflow of ambient outdoor air, depending on the total enthalpy of the outdoor air, so as to satisfy cooling and the dehumidification requirements without operating the refrigeration unit when the enthalpy of the outdoor air is suitable. The system includes a programmable controller for controlling air temperature and humidity within the enclosed space by sensing outdoor air enthalpy, temperature and humidity of air within the enclosed space and temperature or enthalpy of supply air being admitted to the enclosed space.

Claims

1. A space conditioning system for conditioning air within an enclosed space, comprising:

an air mover for circulating air to an enclosed space;

a first heat exchanger for cooling air being circulated to the enclosed space;

a second heat exchanger disposed to heat air being circulated to the enclosed space to a temperature above the temperature of air discharged from said first heat exchanger;

a duct in communication with said first heat exchanger for circulating air from the enclosed space through said first and second heat exchangers and said air mover for circulation back to the enclosed space;

a vapor refrigeration unit, including a compressor, a condenser, a first conduit for conducting condensed refrigerant fluid from said compressor to said first heat exchanger and a second conduit for conducting heated refrigerant gas from said compressor to said second heat exchanger; and

a control system, including a humidity sensor for sensing a humidity corresponding to humidity of air in the enclosed space and a controller operably connected to said humidity sensor, said refrigeration unit being responsive to a control signal from said controller indicating that the humidity is above a setpoint of said humidity sensor to conduct heated refrigerant gas from said compressor to said second heat exchanger and from said second heat exchanger to said condenser and to conduct condensed refrigerant fluid from said condenser to said first heat exchanger, whereby air being circulated to the enclosed space is cooled and dehumidified by said first heat exchanger and is reheated by said second heat exchanger.

2. The space conditioning system of claim 1 wherein said control system is operative to prevent said space conditioning system from conducting heated refrigerant gas from said compressor to said second heat exchanger in response to any demand for cooling air in the enclosed space.

3. The space conditioning system of claim 1 wherein said control system is operative to cause said space conditioning system to discontinue conducting heated refrigerant gas from said compressor to said second heat exchanger in response to any demand for cooling air in the enclosed space.

4. The space conditioning system of claim 1 wherein said refrigeration unit is responsive to said control signal to conduct heated refrigerant gas from said compressor to said second heat exchanger in the absence of a demand for cooling in the enclosed space.

5. The space conditioning system of claim 1 further including a damper for admitting outdoor ambient air to said space conditioning system for circulation to the enclosed space, a first enthalpy sensor for sensing the enthalpy of the outdoor ambient air and a second enthalpy sensor for sensing the enthalpy of air being circulated to the enclosed space, said controller being operative to control said damper to allow the outdoor ambient air to be admitted to said space conditioning system when the enthalpy of the outdoor ambient air is less than the enthalpy of the air being circulated to the enclosed space and to inhibit the outdoor ambient air from being admitted to said space conditioning system when the enthalpy of the outdoor ambient air is greater than or equal to the enthalpy of the air being circulated to the enclosed space.

6. The space conditioning system of claim 5 wherein said controller is operative to control relative proportions of the outdoor ambient air and air returned from the enclosed space in the air which is circulated by said space conditioning system to the enclosed space.

7. The space conditioning system of claim 1 further including a damper for admitting outdoor ambient air to said space conditioning system for circulation to the enclosed space and a temperature sensor for sensing the temperature of air being circulated to the enclosed space, said temperature sensor being operably connected to said controller for causing said controller to control relative proportions of the outdoor ambient air and air returned from the enclosed space in the air being circulated to the enclosed space.

8. The space conditioning system of claim 1 further including a cabinet enclosing said first and second heat exchangers, said cabinet including an inlet opening for conducting air circulated to said space conditioning system from the enclosed space and a discharge opening for supplying air from said space conditioning system to the enclosed space, a return air space in said cabinet for receiving air returned from the enclosed space, and an outdoor air space in said cabinet in communication with outdoor ambient air for conducting the outdoor ambient air through said cabinet to the enclosed space, said space conditioning system further including a damper for controlling flow of the outdoor ambient air into said cabinet and to the enclosed space.

9. The space conditioning system of claim 8 wherein said humidity sensor is disposed within one of said return air space and the enclosed space.

10. The space conditioning system of claim 1 wherein said control system includes an enthalpy sensor for sensing the enthalpy of outdoor ambient air, said controller being operably connected to said humidity sensor and said enthalpy sensor for selectively controlling said space conditioning system to provide the enclosed space with dehumidified air by cooling and reheating air by said first and second heat exchangers or from the outdoor ambient air, depending on the enthalpy of the outdoor ambient air, in response to said control signal.

11. A space conditioning system for conditioning air within an enclosed space, comprising:

an air mover for circulating air to the enclosed space;

a first heat exchanger for cooling air being circulated to the enclosed space;

a second heat exchanger disposed to heat air being circulated to the enclosed space to a temperature above the temperature of air discharged from said first heat exchanger;

a duct in communication with said first heat exchanger for circulating air from the enclosed space through said first and second heat exchangers and said air mover for circulation back to the enclosed space;

a humidity sensor for sensing a humidity corresponding to humidity of air in the enclosed space; and

a controller operably connected to said humidity sensor for selectively controlling said space conditioning system to provide the enclosed space with dehumidified air by cooling and reheating air by said first and second heat exchangers in response to the humidity being above being above a setpoint of said humidity sensor in the absence of a demand for cooling in the enclosed space.

12. The space conditioning system of claim 11 wherein said control system is operative to prevent said space conditioning system from reheating air by said second heat exchanger in response to any demand for cooling air in the enclosed space.

13. The space conditioning system of claim 11 wherein said control system is operative to cause said space conditioning system to discontinue reheating air by said second heat exchanger in response to any demand for cooling in the enclosed space.

14. The space conditioning system of claim 11 wherein said control system includes an enthalpy sensor for sensing the enthalpy of outdoor ambient air, said controller being operably connected to said humidity sensor and said enthalpy sensor for selectively controlling said space conditioning system to provide the enclosed space with dehumidified air by cooling and reheating air by said first and second heat exchangers or from the outdoor ambient air, depending on the enthalpy of the outdoor ambient air, in response to said control signal.

15. The space conditioning system of claim 11 further including a damper for admitting outdoor ambient air to said space conditioning system for circulation to the enclosed space, a first enthalpy sensor for sensing the enthalpy of the outdoor ambient air and a second enthalpy sensor for sensing the enthalpy of air being circulated to the enclosed space, said controller being operative to control said damper to allow outdoor ambient air to be admitted to said space conditioning system when the enthalpy of the outdoor ambient air is less than the enthalpy of air being circulated to the enclosed space and to inhibit the outdoor ambient air from being admitted to said space conditioning system when the enthalpy of the outdoor ambient air is greater than or equal to the enthalpy of the air being circulated to the enclosed space.

16. The space conditioning system of claim 15 wherein said controller is operative to control the relative proportions of the outdoor ambient air and air returned from the enclosed space in the air which is circulated by said space conditioning system to the enclosed space.

17. The space conditioning system of claim 11 further including a damper for admitting outdoor ambient air to said space conditioning system for circulation to the enclosed space and a temperature sensor for sensing the temperature of air being circulated to the enclosed space, said temperature sensor being operably connected to said controller for causing said controller to control the relative proportions of outdoor ambient air and air returned from the enclosed space in the air which is circulated by said space conditioning system to the enclosed space.

18. The space conditioning system of claim 11 further including a cabinet enclosing said first and second heat exchangers, said cabinet including an inlet opening for conducting air circulated to said space conditioning system from the enclosed space and a discharge opening for supplying air from said space conditioning system to the enclosed space, a return air space in said cabinet, and an outdoor air space in said cabinet in communication with outdoor ambient air for conducting the outdoor ambient air through said cabinet to the enclosed space, said space conditioning system further including a damper for controlling flow of the outdoor ambient air into said cabinet and to the enclosed space.

19. The space conditioning system of claim 18 wherein said humidity sensor is disposed within one of said return air space and the enclosed space.