Patent Publication Number: US-2023143201-A1

Title: Methods and systems for controlling integrated air conditioning systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. application Ser. No. 15/888,504 filed Feb. 5, 2018, which is a division of U.S. patent application Ser. No. 12/674,135 filed Feb. 18, 2010, and further claims the benefit of an earlier filing date from PCT/US2007/020170, filed Sep. 18, 2007, the contents of which are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure is related to air conditioning systems. More particularly, the present disclosure is related to methods and systems for controlling integrated air conditioning systems having at least two air conditioning systems. 
     2. Description of Related Art 
     During the typical operation of air conditioning systems, the system is run in a cooling mode wherein energy is expended by operating a compressor. The compressor compresses and circulates a refrigerant to chill or condition a working fluid, such as air or other secondary loop fluid (e.g., chilled water or glycol), in a known manner. The conditioned working fluid can then be used in a refrigerator, a freezer, a building, an automobile, and other spaces with climate controlled environment. 
     However, when the outside ambient temperature is low, there exists the possibility that the outside ambient air itself may be utilized to provide cooling to the working fluid without engaging the compressor. When the outside ambient air is used by an air conditioning system to condition the working fluid, the system is referred to as operating in a free-cooling mode. 
     As noted above, traditionally, even when the ambient outside air temperature is low, the air conditioning system is run in the cooling mode. Running in cooling mode under such conditions provides a low efficiency means of conditioning the working fluid. In contrast, running the air conditioning system under such conditions in a free-cooling mode is more efficient. In the free-cooling mode, one or more ventilated heat exchangers and pumps are activated so that the refrigerant is circulated by the pumps and is cooled by the outside ambient air. In this manner, the refrigerant, cooled by the outside ambient air, can be used to cool the working fluid without the need for the low efficiency compressor. 
     Accordingly, it has been determined by the present disclosure that there is a need for methods and systems that improve the efficiency of integrated air conditioning systems. 
     BRIEF SUMMARY OF THE INVENTION 
     An integrated air conditioning system having a first air conditioning unit having a first evaporator with a first input and a first output; a second air conditioning unit having a second evaporator with a second input and a second output; a first conduit fluidly connecting the first input with the second output; a second conduit fluidly connecting the second input with the first output, wherein the first and second conduits and the first and second evaporators form a working fluid circuit. 
     An integrated 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 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 with the second output; a second conduit fluidly connecting the second input with the first output, wherein the first and second conduits and first and second evaporators form a working fluid circuit through which a working fluid flows. 
     A method for controlling an integrated air conditioning system having a first air conditioning unit and a second air conditioning unit, in which 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 into the free-cooling mode. 
     The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. 
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG.  1    is an exemplary embodiment of an air conditioning unit in cooling mode according to the present disclosure; 
       FIG.  2    is an exemplary embodiment of an air conditioning unit in free-cooling mode according to the present disclosure; and 
       FIG.  3    illustrates an exemplary embodiment of an air conditioning system comprised of the air conditioning units of  FIGS.  1  and  2    according to the present disclosure. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings and in particular to  FIGS.  1  and  2   , an exemplary embodiment of an air conditioning unit (“unit”) according to the present disclosure, generally referred to by reference numeral  10 , is shown. As seen in  FIG.  3   , two air conditioning units  10 - 1  and  10 - 2  can be integrated to form an air conditioning system  42 . Advantageously, air conditioning system  42  provides for working fluid  22  to pass from unit  10 - 1  to unit  10 - 2  during a switch from cooling mode to free-cooling mode, or vice versa. Thus, there is no stoppage in the conditioning of the working fluid. 
     Unit  10  includes a controller  30  for selectively switching between cooling and free-cooling modes  32 ,  34 . Unit  10  also includes a refrigeration circuit  36  that includes a condenser  14 , a pump  16 , an expansion device  18 , an evaporator  20 , an evaporator input  34 , an evaporator output  48 , and a compressor  12 . Controller  30  selectively controls either compressor  12  (when in cooling mode  32 ) or pump  16  (when in free-cooling mode  34 ) to circulate a refrigerant through system  10  in a flow direction  28 . Thus, unit  10 , when in cooling mode  32 , controls compressor  12  to compress and circulate the refrigerant in flow direction  28 . However, unit  10 , when in free-cooling mode  34 , controls pump  16  to circulate the refrigerant in flow direction  28 . As such, free-cooling mode  34  uses less energy than cooling mode  32  since the free-cooling mode does not require the energy expended by compressor  12 . 
     Unit  10  includes a compressor by-pass loop  46  and a pump by-pass loop  34 . 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 and close by-pass loops  44 ,  46  as desired. 
     In cooling mode  32 , controller  30  controls valves  24 ,  26 , and  38  so that compressor by-pass loop  44  is closed and pump by-pass loop  46  is open. In this manner, unit  10  allows compressor  12  to compress and circulate refrigerant in flow direction  28  by flowing through pump by-pass loop  46 . 
     In contrast, controller  30 , when in free-cooling mode  34 , controls valves  24 ,  26 , and  38  so that compressor by-pass loop  44  is open and pump by-pass loop  46  is closed. In this manner, unit  10  allows pump  16  to circulate refrigerant in flow direction  28  by flowing through compressor by-pass loop  44 . 
     Evaporator  20  includes evaporator input  34  (through which working fluid  22  enters the evaporator) and evaporator output  48  through which working fluid  22  exits the evaporator. Within evaporator  20 , working fluid  22  is in heat-exchange communication with the refrigerant in both cooling and free-cooling modes  32 ,  34 . Working fluid  22  can be ambient indoor 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 in which the compression and expansion of refrigerant via expansion device  18  are 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  takes advantage of the heat removing capacity of outdoor ambient air, which is in heat exchange relationship with condenser  14  via one or more fans to condition working fluid  22 . 
     Although unit  10  is described herein as a conventional air conditioning (cooling) unit, one skilled in the art will recognize that unit  10  may also be a heat pump system to provide both heating and cooling by adding a reversing valve (not shown) so that condenser  14  (i.e., the outdoor heat exchanger) functions as an evaporator in the heating mode and evaporator  20  (i.e., the 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 switchover 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 diminished resulting in a warming of the working fluid. This is counterproductive in that when unit  10  is re-activated, working fluid  22  will have to be conditioned once again. 
     The present disclosure contemplates an air conditioning system  42 , wherein air conditioning units  10 - 1 ,  10 - 2  are integrated systematically and configured such that working fluid  22  circulates through each of the systems. Advantageously, when one of units  10 - 1  or  10 - 2  is temporarily stopped during a switchover between cooling and free-cooling modes, or vice versa, the other unit is running and conditioning working fluid  22 , thus preventing an undue warming of working fluid  22 . 
     Referring now to  FIG.  3   , an exemplary embodiment of system  42  according to the present disclosure is shown. System  42  includes a controller  40 . In one embodiment of the present disclosure, controller  40  is in electrical communication with each one of 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 a switchover from cooling mode  32  to free-cooling mode  34 , or vice versa. 
     System  42  contains first conduit  50  and second conduit  52 . In the embodiment of system  42  shown in  FIG.  3   , first conduit  50  fluidly connects evaporator output  48  of unit  10 - 2  to evaporator input  34  of unit  10 - 1 , thereby allowing working fluid to flow freely between the evaporators. Second conduit  52  fluidly connects evaporator output  48  of unit  10 - 1  to evaporator input  34  of unit  10 - 2 . In one embodiment of the present disclosure, first and second conduits  50 ,  52  are pipes. Advantageously, the addition of first and second conduits  50 ,  52  form working fluid circuit  54  through which working fluid  22  flows freely between units  10 - 1  and  10 - 2 . Advantageously, when either unit  10 - 1  or  10 - 2  is temporarily halted during a switchover between modes, working fluid  22  continues to be conditioned by the other system which is still operating. 
     It should be recognized 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  can be operating in any mode. Furthermore, either system  10 - 1  or  10 - 2  can be in the switchover between modes, while the other system is running. 
     It should also be recognized that even though system  42  is shown having two units  10 - 1  and  10 - 2 , it is contemplated by the present disclosure that system  42  can have more than two systems. 
     In operation, at least one of units  10 - 1  and  10 - 2  is operating in cooling mode  32 . For purposes of example only, unit  10 - 1  is operating in cooling mode  32 . When controller  30  of unit  10 - 1  determines that sufficient conditions are present to run unit  10 - 1  in free-cooling mode  34 , controller  30  communicates with controller  40 . If unit  10 - 2  is currently running, unit  10 - 2  will continue running. However, if unit  10 - 2  is not running, controller  40  sends a signal to controller  30  to turn on unit  10 - 2  in cooling mode. After unit  10 - 2  is turned on and running, unit  10 - 1  initiates a switchover from cooling mode  32  to free-cooling mode  34 . Advantageously, working fluid  22  continues to be conditioned by unit  10 - 2  when unit  10 - 1  is transitioning from cooling mode  32  to free-cooling mode  34 . 
     Although the above example refers to a switchover between cooling mode  32  to free-cooling mode  34 , it should be recognized that unit  10 - 2  may be running in cooling mode  32  and be transitioning to free-cooling mode  34 . 
     It should also be noted that the terms “first”, “second”, “third”, “upper”, “lower”, 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 present disclosure 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 present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.