Integrated dehumidification system

• US 20090277193A1
• Filed: 06/23/2009
• Published: 11/12/2009
• Est. Priority Date: 04/27/2004
• Status: Active Grant

• Current Assignee: Davis Energy Group, Inc.
• Original Assignee: Davis Energy Group, Inc.
• Inventors: Phillips, James H., Springer, David A., Hoeschele, Marc A.
• Granted Patent: US 8,397,522 B2
• Time in Patent Office: Days
• US Class Current: 62/93
• 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 11/77 by controlling the speed of ventilators
• CPC Class Codes: F24F 2110/10 Temperature
• 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 2600/0252 with two speeds
• CPC Class Codes: F25B 40/02 Subcoolers
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A dynamic system controls indoor relative humidity and temperature to achieve specified conditions by applying multiple stages of dehumidification. In addition to a stage that increases dehumidification by reducing the speed of the indoor blower, the system uses a reheat coil and multiple valves that allow the reheat coil to function as either a subcooling coil or a partial condenser. Thus the system can maintain specified indoor temperature and humidity conditions even at times when no heating or cooling is needed. The system may have an outdoor condensing unit including a compressor and a condenser operably connected via refrigerant lines to an indoor unit to form a “split system” refrigerant loop.

Claims

1. A system for controlling environmental conditions in a space, comprising:

a vapor-compression refrigerant loop including at least a 2-speed compressor, a condenser, a reheat coil, an expansion device, a receiver and an evaporator coil;

a variable speed air mover that drives a first air stream sequentially from a space across the evaporator and a reheat coil;

a plurality of valves disposed within the vapor-compression refrigerant loop; and

a controller operably connected to the vapor-compression refrigerant loop, the air mover and the plurality of valves,

wherein the condenser discharges heat to an environment outside the space, and the controller controls a plurality of discrete stages with differing rates of sensible cooling and latent cooling,

the controller selects from among the plurality of stages based on at least one of sensed environmental conditions relative to user input temperature and humidity settings,

a first stage of the plurality of discrete stages provides maximum latent cooling of the first air stream while minimizing sensible cooling and sensible heating of the first air stream,

the sensible cooling corresponds to reducing a measured temperature of the first air stream,

the sensible heating corresponds to increasing a measured temperature of the first air stream, and

the latent cooling corresponds to reducing a humidity of the first air stream.

2. The system of claim 1, wherein the controller selects the first stage by opening a first valve of the plurality of valves at an input to the reheat coil, and opening a second valve of the plurality of valves at an input to the receiver, causing refrigerant to flow through the reheat coil and refrigerant fluid to drain from the reheat coil and pass through the receiver.

3. The system of claim 2, wherein the controller selects the first stage by controlling the condenser fan to maintain substantially equal the sensible heating of the first air stream by the reheat coil and the sensible cooling of the first air stream by the evaporator.

4. The system of claim 1, wherein the plurality of stages includes a second stage that provides enhanced latent cooling with reduced sensible cooling of the first air stream.

5. The system of claim 4, wherein the controller selects the second stage by opening a first valve of the plurality of valves at an input to the reheat coil, and closing a second valve of the plurality of valves at an input to the receiver, causing refrigerant to flow through the reheat coil and refrigerant to bypass the receiver.

6. The system of claim 1, wherein the plurality of stages includes a third stage that controls a ratio of sensible cooling to latent cooling of the first air stream by controlling a speed of the first air stream to change a temperature of the evaporator coil.

7. The system of claim 6, wherein the controller selects the third stage by closing a first valve of the plurality of valves at an input to the reheat coil causing refrigerant flow to bypass the reheat coil and the receiver, and changing a speed of the first air stream.

8. The system of claim 1, wherein the plurality of stages includes a fourth stage that maximizes sensible cooling of the first air stream.

9. The system of claim 8, wherein the controller selects the fourth stage by closing a first valve at an input to the reheat coil causing refrigerant flow to bypass the reheat coil and the receiver.

10. The system of claim 1, wherein the condenser is cooled by a second air stream driven by at least one condenser fan and a flow rate of the second air stream is controlled by controlling the at least one condenser fan.

11. The system of claim 10, wherein the at least one condenser fan operates at substantially a single speed when on, and is cycled on and off to alter a heat exchange rate of the second air stream and to regulate the temperature of the first air stream.

12. The system of claim 4, wherein the controller is operably connected to a temperature sensor and a humidity sensor inside the space, and the controller controls at least one of (1) the air mover, (2) the condenser, and (3) one of the plurality of valves based on input from the temperature sensor and the humidity sensor.

13. The system of claim 12, wherein the first stage is selected when the humidity sensor senses a humidity in the space to be greater than a first preset humidity value and the temperature sensor senses a temperature in the space to be less than a first preset temperature value, and

the second stage is selected when the temperature of the air in the space is between a first preset temperature value and a second preset temperature value.

14. The system according to claim 1,

wherein when a stage is halted, the compressor continues to pump refrigerant from the evaporator until the refrigerant pressure in an inlet of the compressor falls below a first preset value, and

when a stage is started, refrigerant is allowed to flow into the evaporator, and the compressor begins to pump refrigerant when the refrigerant pressure in the inlet of the compressor rises above a second preset value.

15. A method for controlling environmental conditions in a space, comprising:

providing a vapor-compression refrigerant loop including at least a compressor, a condenser, a reheat coil, an expansion device, a receiver and an evaporator coil;

providing a variable flow air mover that drives an air stream from a space sequentially across the evaporator and a reheat coil;

providing a plurality of valves disposed within the vapor-compression refrigerant loop; and

controlling, with a controller, the vapor-compression refrigerant loop, the air mover and the plurality of valves to select from among a plurality of discrete stages with differing rates of sensible cooling and latent cooling based on at least one of sensed environmental conditions relative to predetermined environmental conditions and user input,

wherein the sensible cooling corresponds to reducing a measured temperature of the air stream, and

the latent cooling corresponds to reducing a humidity of the air stream.

16. The method of claim 15, the controller selecting a first stage from among the plurality of stages when the humidity of air in the space is greater than a preset humidity value and the temperature of the air in the space is less than a preset temperature value, by opening a first valve of the plurality of valves at an input to the reheat coil, and opening a second valve of the plurality of valves at an input to the receiver, causing refrigerant to flow through the reheat coil and refrigerant fluid to drain from the reheat coil and pass through the receiver, the first stage providing maximum latent cooling of the air stream while minimizing the sensible cooling and sensible heating of the air stream.

17. The method of claim 15, the controller selecting a second stage from among the plurality of stages when the temperature of the air in the space is between a first preset temperature value and a second preset temperature value, by opening a first valve of the plurality of valves at an input to the reheat coil and closing a second valve of the plurality of valves at an input to the receiver, causing refrigerant to flow through the reheat coil and refrigerant to bypass the receiver, the second stage providing enhanced latent cooling with reduced sensible cooling of the air stream.

18. The method of claim 15, the controller selecting a third stage from among the plurality of stages when the humidity of the air in the space is less than a first preset humidity value and greater than a second preset humidity value, by closing a first valve at an input to the reheat coil, causing refrigerant flow to bypass the reheat coil and the receiver, the controller controlling a ratio of sensible cooling to latent cooling of the air stream by controlling a speed of the air stream to change a temperature of the evaporator coil.

19. The method of claim 15, the controller selecting a fourth stage from among the plurality of stages when the humidity of air in the space is less than a preset humidity value and the temperature of the air in the space is greater than a preset temperature value, by closing a first valve at an input to the reheat coil, causing refrigerant flow to bypass the reheat coil and the receiver, the fourth stage maximizing sensible cooling of the air stream.