HK1147308B - Methods and systems for controlling integrated air conditioning systems - Google Patents

Description

Method and system for controlling combined air conditioning system

Technical Field

The present invention relates to an air conditioning system. More particularly, the present invention relates to a method and system for controlling a combined air conditioning system having at least two air conditioning systems.

Background

During typical operation of an air conditioning system, the system operates in a cooling mode in which energy is consumed by operating the compressor. The compressor compresses and circulates a refrigerant in a known manner to cool or condition a working fluid, such as air or other secondary loop fluid (e.g., cooling water or glycol). The conditioned working fluid can then be applied to refrigerators, freezers, buildings, automobiles, and other spaces having a temperature controlled environment (climate controlled environment).

However, when the outdoor ambient temperature is low, there is a possibility that the outdoor ambient air itself may be used to provide cooling of the working fluid without engaging the compressor. When the air conditioning system uses outdoor ambient air to condition the working fluid, the system is said to operate in a free-cooling mode.

As described above, conventionally, air conditioning systems operate in a cooling mode even when the ambient outdoor air temperature is low. In this case, operating in the cooling mode provides an inefficient means of conditioning the working fluid. In this case, on the contrary, it is more efficient to operate the air conditioning system in the free cooling mode. In the free-cooling mode, one or more vent heat exchangers and pumps are activated such that the refrigerant is circulated by the pumps and cooled by the outdoor ambient air. In this manner, the refrigerant cooled by the outdoor ambient air can be used to cool the working fluid without reducing compressor efficiency.

Accordingly, the present invention identifies a need for a method and system for improving the efficiency of a combined air conditioning system.

Disclosure of Invention

A combined air conditioning system having: a first air conditioning unit (air conditioning unit) having a first evaporator having a first input port and a first output port; a second air conditioning unit having a second evaporator with a second input port and a second output port; a first conduit fluidly connecting the first input port with the second output port; a second conduit fluidly connecting the second input port with the first output port, wherein the first and second conduits and the first and second evaporators form a working fluid circuit.

A combined air conditioning system having: a first air conditioning unit having a first evaporator with a first inlet and a first outlet, a first pump, and a first refrigeration circuit, the first air conditioning unit having a first cooling mode and a first free-cooling mode; a second air conditioning unit having a second evaporator with a second inlet and a second outlet, a second pump, and a second refrigeration circuit, the second air conditioning unit having a second cooling mode and a second free-cooling mode; a first conduit fluidly connecting the first input port with the second output port; a second conduit fluidly connecting the second input port with the first output port, wherein the first and second conduits and first and second evaporators form a working fluid circuit within which a working fluid flows.

A method for controlling a combined air conditioning system having a first air conditioning unit and a second air conditioning unit, wherein the first air conditioning unit and the second air conditioning unit are in heat exchange communication with a working fluid. The method includes switching the first air conditioning unit from a cooling mode to a free-cooling mode; and operating the second air conditioning unit for a predetermined period of time after switching the first air conditioning unit to the free-cooling mode.

The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.

Drawings

FIG. 1 is an exemplary embodiment of an air conditioning unit in a cooling mode according to the present invention;

FIG. 2 is an exemplary embodiment of an air conditioning unit in a free-cooling mode according to the present invention;

fig. 3 shows an exemplary embodiment of an air conditioning system according to the present invention, consisting of the air conditioning units of fig. 1 and 2.

Detailed Description

Referring now to the drawings, and in particular to fig. 1 and 2, there is shown an exemplary embodiment of an air conditioning unit ("unit") according to the present invention, generally designated by the reference numeral 10. As shown in fig. 3, two air conditioning units 10-1 and 10-2 can be combined to form an air conditioning system 42. Advantageously, during the switch from cooling mode to free-cooling mode, air conditioning system 42 delivers working fluid 22 from unit 10-1 to unit 10-2 and vice versa. Thus, there is no stop in regulating the working fluid.

Unit 10 includes a controller 30, controller 30 for selectively switching between a cooling mode 32 and a free-cooling mode 34. The unit 10 also includes a refrigeration circuit 36, the refrigeration circuit 36 including the condenser 14, the pump 16, the expansion device 18, the evaporator 20, the evaporator input 34, the evaporator output 48, and the compressor 12. Controller 30 selectively controls compressor 12 (when in cooling mode 32) or pump 16 (when in free-cooling mode 34) to circulate refrigerant through system 10 in flow direction 28. Thus, unit 10 controls compressor 12 in cooling mode 32 to compress and circulate the refrigerant in flow direction 28. However, unit 10 controls pump 16 in free-cooling mode 34 to circulate the refrigerant in flow direction 28. Thus, free-cooling mode 34 uses less energy than cooling mode 32 because free-cooling mode does not require the energy consumed by compressor 12.

Unit 10 includes a compressor bypass loop 46 and a pump bypass loop 34. The unit 10 includes one or more valves 24, 26 and 38. Valves 24, 26 and 38 are controlled by controller 30 in a known manner. Thus, controller 30 can selectively position valves 24, 26, and 38 to selectively open (open) and close (close) bypass circuits 44, 46 as desired.

In cooling mode 32, controller 30 controls valves 24, 26, and 38 such that compressor bypass circuit 44 is closed and pump bypass circuit 46 is open. In this manner, unit 10 allows compressor 12 to compress and circulate refrigerant in flow direction 28 through pump bypass loop 46.

In contrast, controller 30 controls valves 24, 26, and 38 in free-cooling mode 34 such that compressor bypass circuit 44 is open and pump bypass circuit 46 is closed. In this manner, unit 10 allows pump 16 to circulate refrigerant through compressor bypass circuit 44 in flow direction 28.

The evaporator 20 includes an evaporator input 34 through which the working fluid 22 enters the evaporator and an evaporator output 48 through which the working fluid 22 exits the evaporator. Within evaporator 20, working fluid 22 is in heat exchange communication with a refrigerant in both cooling mode 32 and free-cooling mode 34. The working fluid 22 can be ambient room air (ambient air) or a secondary loop fluid such as, but not limited to, chilled water or glycol.

In cooling mode 32, unit 10 operates as a standard vapor compression air conditioning system known in the art, wherein the compression and expansion of refrigerant through expansion device 18 is used to condition working fluid 22. Expansion device 18 can be any known controllable expansion device, such as, but not limited to, a thermal expansion valve.

In free-cooling mode 34, unit 10 utilizes the heat removal capability of outdoor ambient air, which is conditioned with working fluid 22 via one or more fans, in heat exchange relationship with condenser 14.

Although the unit 10 is described herein as a conventional air conditioning (cooling) unit, those skilled in the art will appreciate that the unit 10 may also be a heat pump system, whereby heating or cooling is provided by the addition of a reversing valve (not shown) such that the condenser 14 (i.e., outdoor heat exchanger) functions as an evaporator in the heating mode and the evaporator 20 (i.e., indoor heat exchanger) functions as a condenser in the heating mode.

Unfortunately, it has been determined by the present disclosure that when controller 30 initiates a switch from cooling mode 32 to free-cooling mode 34, or vice versa, refrigeration circuit 36 is temporarily stopped. When refrigeration circuit 36 is stopped, the heat exchange between the refrigerant and working fluid 22 is reduced, causing the working fluid to warm. This will have the opposite effect, since the working fluid 22 will have to be conditioned again when the unit 10 is restarted.

The present invention contemplates an air conditioning system 42 in which air conditioning units 10-1, 10-2 are systematically combined and configured to circulate working fluid 22 through each of the systems. Advantageously, when one of the units 10-1 or 10-2 is temporarily stopped during switching between the cooling mode and the free-cooling mode, or vice versa, the other unit remains running and regulates the working fluid 22, thereby preventing the working fluid 22 from being excessively warmed.

Referring now to FIG. 3, an exemplary embodiment of a system 42 according to the present invention is shown. The system 42 includes a controller 40. In one embodiment of the present invention, controller 40 is in electrical communication with each of the controllers 30 of air conditioning units 10-1 and 10-2 and coordinates the operation of the units when either of the units is temporarily stopped during the switch from cooling mode 32 to free-cooling mode 34, and vice versa.

The system 42 includes a first conduit (conduit)50 and a second conduit 52. In the embodiment of the system 42 shown in fig. 3, the first conduit 50 fluidly connects the evaporator output 48 of the unit 10-2 to the evaporator input 34 of the unit 10-1, thus allowing the working fluid to flow freely between the evaporators. A second conduit 52 fluidly connects the evaporator output 48 of unit 10-1 to the evaporator input 34 of unit 10-2. In one embodiment of the present invention, the first conduit 50 and the second conduit 52 are pipes. Advantageously, the first and second conduits 50, 52 together form a working fluid circuit 54 through which the working fluid 22 flows freely between the units 10-1 and 10-2. Advantageously, when either of the units 10-1 or 10-2 temporarily stops during the switch between modes, the working fluid 22 continues to be conditioned by the other systems that are still running.

It should be appreciated that although system 10-1 is shown in cooling mode 32 and system 10-2 is shown in free-cooling mode 34, systems 10-1 and 10-2 may operate in any mode. In addition, while either system 10-1 or 10-2 is operating, the other system can still switch between modes.

It should also be appreciated that although the system 42 is shown with two units 10-1 and 10-2, the present invention contemplates that the system 42 can have more than two systems.

In operation, at least one of the units 10-1 and 10-2 is operated in the cooling mode 32. For exemplary purposes only, the unit 10-1 operates in the cooling mode 32. When controller 30 of unit 10-1 determines that sufficient conditions exist to operate unit 10-1 in free-cooling mode 34, controller 30 communicates with controller 40. If unit 10-2 is currently operating, unit 10-2 will continue to operate as well. However, if the unit 10-2 is not operating, the controller 40 sends a signal to the controller 30 to turn on the unit 10-2 in the cooling mode. After unit 10-2 is turned on and operational, unit 10-1 initiates a switch from cooling mode 32 to free-cooling mode 34. Advantageously, unit 10-2 continues to condition working fluid 22 as unit 10-1 transitions from cooling mode 32 to free-cooling mode 34.

Although the above example refers to switching between cooling mode 32 to free-cooling mode 34, it should be appreciated that unit 10-2 may operate in cooling mode 32 and may transition to free-cooling mode 34.

It should be noted that the terms "first," "second," "third," "high," "low," and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated.

While the invention has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (7)

1. A combination air conditioning system, comprising:

a first air conditioning unit having a first compressor and a first evaporator, the first evaporator having a first inlet and a first outlet, a first pump, and a first refrigeration circuit, the first air conditioning unit having a first cooling mode and a first free-cooling mode;

a second air conditioning unit having a second compressor and a second evaporator, the second evaporator having a second inlet and a second outlet, a second pump, and a second refrigeration circuit, the second air conditioning unit having a second cooling mode and a second free-cooling mode;

a first conduit fluidly connecting the first inlet with the second outlet; and

a second conduit fluidly connecting the second inlet with the first outlet, wherein the first and second conduits and first and second evaporators form a working fluid circuit within which a working fluid flows.

2. The combined air conditioning system of claim 1, wherein the working fluid is cooling water or glycol.

3. The combination air conditioning system of claim 1, wherein during a temporary stop of the first air conditioning unit or the second air conditioning unit, the working fluid circuit maintains the working fluid flowing through the first air conditioning unit and the second air conditioning unit, thereby minimizing a temperature rise of the working fluid during the temporary stop.

4. The combination air conditioning system of claim 1, further comprising a controller in electrical communication with the first air conditioning unit and the second air conditioning unit.

5. A method for controlling a combined air conditioning system having a first air conditioning unit and a second air conditioning unit, wherein the first air conditioning unit has a first compressor and the second air conditioning unit has a second compressor, the first and second air conditioning units being in heat exchange communication with a working fluid, the method comprising:

switching the first air conditioning unit from a cooling mode to a free-cooling mode; and

operating the second air conditioning unit for a predetermined period of time after switching the first air conditioning unit to the free-cooling mode.

6. The method of claim 5, wherein the step of operating the second air conditioning unit comprises turning on the second air conditioning unit.

7. The method of claim 5, wherein the step of operating the second air conditioning unit comprises maintaining operation of the second air conditioning unit if the second air conditioning unit was previously operating.