Abstract:
Disclosed is an improved variable refrigerant flow (VRF) air conditioning (AC) unit that eliminates the need to run refrigerant lines into the spaces being cooled or heated while providing the benefits and energy savings of a VRF system. Suitably, the disclosed VRF AC system can connects multiple condensate drain pans via one pipe then uses gravity to drain condensation from the condenser coils. Further disclosed is a VRF AC system that provides the required minimum outside air as an integral part of the system. Finally, disclosed may be a VRF AC system that has an economizer to use outside air to cool inside air if the outside air temperature is lower than the inside air temperature.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation-in-part patent application of application Ser. No. 15/199,642 (filed Jun. 30, 2016) entitled “Improvements to variable refrigerant flow (VRF) air conditioning and related methods.” 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       REFERENCE TO AN APPENDIX SUBMITTED ON A COMPACT DISC AND AN INCORPORATED BY REFERENCE OF THE MATERIAL ON THE COMPACT DISC 
       [0004]    Not applicable. 
       STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINT INVENTOR 
       [0005]    Reserved for a later date, if necessary. 
       BACKGROUND OF THE INVENTION 
     Field of Invention 
       [0006]    The disclosed subject matter is in the field of systems of variable refrigerant flow (VRF) air conditioning (AC) units. 
       Background of the Invention 
       [0007]    Variable refrigerant flow or VRF is a technology in the field of heating, ventilating, and air conditioning (HVAC). HVAC technology is important for the design of office buildings, where thermal comfort and acceptable air quality are regulated. In the typical case, indoor temperature regulation (the H or AC of HVAC) is accomplished by outdoor condenser coils with refrigerant that circulates via copper tubing to corresponding evaporation coils localized at various zones within the building. Ventilation (the V in HVAC) involves exchanging internal air with external air. 
         [0008]    In typical HVAC systems for buildings with multiple zones to be cooled, refrigerant lines are run from a rooftop condensation coil to a localized evaporation coil at each zone to be cooled. A fan at each zone blows air over the evaporation coil so that heat is exchanged from the blown air and the refrigerant. During air cooling heat exchange, heat is transferred to the refrigerant as the refrigerant evaporates within the coils. Sometimes, such heat exchange causes moisture from the air to condense on the evaporation coils. After heat is exchanged between the refrigerant and the air to achieve conditioned air, the conditioned air is provided within the local zone while the refrigerant is pumped to the rooftop condensation coil. In the condensation coil outside of the building, the heat in the refrigerant is exchanged or dumped to the ambient heat sink as the refrigerant is condensed within the condensation coils. Finally, any moisture from the evaporation coils may be pumped outside of the building for drainage. Meanwhile, a ventilation fan circulates a constant flow of fresh air in and an equally constant out flow of exhaust air from the localized zones. 
         [0009]    Several problems arise with typical temperature control in known HVAC systems. One problem is that standard HVAC systems require hundreds of feet of expensive copper tubing to circulate refrigerant between the rooftop condenser and localized evaporation coils. This problem is magnified in multi-unit buildings because copper tubing may be provided to each unit. This circulation of refrigerant risks exposure of users of the HVAC system to potentially toxic refrigerant because the refrigerant is provided to evaporation coils within each zone to be cooled. The circulation of refrigerant to every zone to be cooled further reduces the overall efficiency of the system since energy is required to move the fluid back-and-forth through the piping from the condenser coils to the localized cooling units (evaporation coils) within the building. Another problem is that each of the localized evaporation coils generate moisture at their particular zone during cooling and said moisture must be taken from the local evaporation coil to outside of the building for disposal. Disposal of the moisture created by these coils usually requires a pump to move the fluid and, as a result, further decreases the overall energy efficiency of the typical HVAC unit. 
         [0010]    Several problems also arise with typical ventilating fans in known HVAC systems. One problem is that the venting fans inefficiently circulate air. Office building codes often feature air quality standards that require that a percentage of the inside air be replenished with an outside air over certain designated times. A constant supply of external air from known HVAC systems is not always enough to replace the required amount of air so that additional airflow systems are required to supplement the constant airflows of known HVAC systems. Furthermore, the known ventilating fans of HVAC systems are inefficient because they do not take advantage of cool external air to cool internal air and rely solely on the condensation cycle of refrigerant for temperature control. 
       SUMMARY OF THE INVENTION 
       [0011]    In view of the foregoing, an object of this specification is to disclose an improved variable refrigerant flow (VRF) air conditioning (AC) unit that eliminates the need to run refrigerant lines into the spaces being cooled or heated while providing the benefits and energy savings of a VRF system. It is a further object to disclose a VRF AC system that connects multiple condensate drain pans via one pipe then uses gravity to drain condensation from the condenser coils. It is yet another object of this disclosure to describe a VRF AC system that provides the required minimum outside air as an integral part of the system. Yet another objective of this disclosure is to provide an HVAC system that consolidates fans and refrigerant cycles. Finally, it is an objective of this paper to present a VRF AC system that has an economizer to use outside air to cool inside air if the outside air temperature is lower than the inside air temperature. 
         [0012]    In one embodiment, the invention may be a packaged rooftop VRF AC unit that cools and heats multiple zones (or areas/rooms) of a building simultaneously. In a preferred embodiment, the unit is self-contained with flexible geometry to match existing zones of the building (i.e., the unit can be retrofit to existing structures easily). 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0013]    Other objectives of the disclosure will become apparent to those skilled in the art once the invention has been shown and described. The manner in which these objectives and other desirable characteristics can be obtained is explained in the following description and attached figures in which: 
           [0014]      FIG. 1  is a perspective view of a preferred embodiment of the VRF system; 
           [0015]      FIG. 2  is a plan view of the preferred embodiment of the VRF system; 
           [0016]      FIG. 3  is a side view of the preferred embodiment of the VRF system; 
           [0017]      FIG. 4  is an end wall view of the preferred embodiment of the VRF system; 
           [0018]      FIG. 5  is an air flow diagram; 
           [0019]      FIG. 6  a dimensioned plan view of the preferred embodiment the VRF; 
           [0020]      FIG. 7  is a dimensioned side view of the preferred embodiment of the VRF system; and, 
           [0021]      FIG. 8  is a dimensioned end wall view of the preferred embodiment of the VRF system. 
           [0022]      FIG. 9  a plan view of an alternate embodiment the VRF; 
           [0023]      FIG. 10  is a side view of the alternate embodiment of the VRF system; 
           [0024]      FIG. 11  is an end wall view of the preferred embodiment of the VRF system; 
           [0025]      FIG. 12  is a diagram of the base of the VRF system; and, 
           [0026]      FIG. 13  illustrates the installation of the VRF system. 
       
    
    
       [0027]    In a typical case, the system may feature the following components with numerals that correspond to the numerals in the figures:
   ( 1210 ) Mitsubishi R2 series fan;   ( 1310 ) an outside air damper;   ( 1320 ) a louver;   ( 1340 ) a filter bank;   ( 1341 ) filter gauge   ( 1342 ) access door   ( 1350 ) an supply air opening;   ( 1351 ) a supply fan and motor assembly;   ( 1352 ) an access door;   ( 1360 ) a return air opening   ( 1365 ) exhaust fan   ( 1366 ) motor assembly.   ( 1367 ) an access door;   ( 1368 ) an access door;   ( 1370 ) exhaust air vent;   ( 1371 ) a backdraft damper;   ( 1372 ) exhaust air louver.   ( 1390 ) expansion coil;   ( 1392 ) a control enclosure;   ( 1391 ) a controller;   ( 1393 ) a drain connection;   ( 1394 ) a removable panel or access door; and,   ( 1395 ) a supply fan (SF) &amp; exhaust fan (EF) variable frequency drives (VFDs).   
 
         [0051]    It is to be noted, however, that the appended figures illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments that will be appreciated by those reasonably skilled in the relevant arts. Also, figures are not necessarily made to scale but are representative. 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0052]    Disclosed is as a rooftop HVAC system  1000 .  FIG. 1  is a perspective view of the preferred embodiment of system  1000 .  FIG. 2  is a plan view of the preferred embodiment of the system  1000 .  FIG. 3  is a side view of the preferred embodiment of the system  1000 .  FIG. 4  is an end wall view of the system  1000 . As shown the system comprises: a platform  1100 ; an external condensing unit  1200 ; and, a venting box  1300 . 
         [0053]    Referring to the figures, the external condensing unit suitably features two fans  1210  (e.g., Mitsubishi R2 series fans) that move air over the condenser coils to extract heat from a refrigerant and exhaust the heated air to the ambient heat-sink. Suitably, refrigerant may be cycled to expansion coils  1390  inside the venting box  1300  so that air taken into the venting box  1300  may be conditioned. 
         [0054]    As shown, the venting box  1300  suitably features an outside air damper  1310  on both sides of the venting box  1300  (see  FIG. 2 ). Suitably, the damper  1310  may be a valve or plate that stops or regulates the flow of into the venting box  1300 . Suitably, the damper  1310  may be used to cut off the flow of air from the outside of the venting box  1300  to the inside of the venting box  1300 . In one embodiment, the damper(s)  1310  are 16 W×30 H OSA dampers or actuators. Suitably, the damper(s)  1310  feature louvers  1320  that are slatted downward to admit air into the venting box  1300  while keeping out rain. Suitably, the angle of the slats of the louvers  1320  may be adjustable or fixed. Once inside the venting box  1300 , air that has passed through the dampers  1310  into the venting box  1360  may suitably be conditioned as discussed in detail below. 
         [0055]    Still referring to  FIGS. 2 through 4 , the venting box  1300  preferably features a filter bank  1340 . Suitably, the filter bank  1340  has a plurality of filters for removing particulates from the air received through the damper  1310 . In a preferred embodiment an array of filters are employed to clean the air to appropriate air quality control standards. In one embodiment, a filter gauge  1341  may be employed on the outside of the venting box  1300  so that the filters can be changed according to an appropriate schedule. In a preferred embodiment, the venting box  1300  may feature an access door  1342  so that the filter bank  1340  may be accessed and the associated filters replaced or maintained. 
         [0056]    Still referring to  FIG. 2 , the venting box  1300  suitably features at least one supply air opening  1350  on its floor. In use, the supply air opening  1350  permits conditioned air to exit the venting box  1300  toward the space (not shown) (e.g. a building) to be cooled. In a preferred embodiment, the venting box  1300  suitably features at least one supply air fan and motor assembly  1351  that is positioned inside the venting box  1300  adjacent to the filter bank  1340 . In operation, the fan  1351  drives air through the damper  1310 , through the filter bank  1340 , and toward the supply air opening  1350 . Suitably, an access door  1352  is provided to the venting box  1300  so that maintenance may be conducted on the supply air fan and motor assembly  1351 . As discussed in detail below, the supply air opening  1350  suitably is divided by ducts into separate air pathways so that multiple spaces may be cooled separately. 
         [0057]      FIG. 4  is a rear plan view of the venting box  1300 . As shown, the view shows the expansion coil array  1390 . Suitably, each expansion coil is independently controlled for conditioning air that passes over the coils  1390 . In a preferred embodiment, each coil conditions air for a separate zone of a building (not shown). Suitably, as discussed above, each coil features a damper and ducting so that air conditioning by each coil  1390  may separately be provided through the supply air opening  1350 . In a preferred embodiment, driving force for the air is the air supply fan and motor assay  1351 . Suitably, the conditioning of the air by the various coils  1390  may suitably be controlled by a controller  1391  (e.g., a Mitsubishi BC controller CMB-P105NU-G) with control components stored in the control enclosure  1392  (e.g., a 36 W×66 H×8 D control enclosure). Although the coils  1390  are programed to condition air at different settings, suitably, each coil  1390  is for each zone being serviced by the cooling units  1390  has its own drain pan and all drain pans associated with each zone are manifolded together to create a single drain  1393  for discharging condensate from the venting box  1300 . Suitably, gravity is the driving force for drainage. In a preferred embodiment, each zone does not have its own fan and all rely on the operation of the fan  1351  for movement of air to all zones. Access doors  1394  may be provided so that the coils and cooling units  1390  or controllers  1391  may be accessible inside the venting box  1300 . Copper tubing may be provided to the coils from the condenser unit  1200  so that refrigerant may be cycled through the system  1000 . 
         [0058]    In one embodiment, the system preferably has a system control for the packaged VRF Multi-zone Unit. Suitably, the controller may be capable of controlling individual zones and supply fan air volume and pressure. The zone air volume can be controlled in various ways depending to user preference or local code requirements. In one embodiment, the two main methods are (1) constant volume or (2) variable volume. The constant volume control method involves a scenario where each zone has a “manual fix in position damper.” The damper may suitably be set at a fixed position to deliver a constant amount of air to a space during heating, cooling or ventilation modes. Suitably, the system requires an air balance and supply fan that are also set in a fixed position. The variable volume control method involves a scenario where each zone is equipped with a modulating damper. According to control logic: (A) the damper will go to “full open position” when there is a call for heating or cooling; (B) the damper will go to “minimum position” when a temperature set point has been reached and there is no need for heating or cooling; and, (C) the damper will go to “full closed position” during unoccupied mode. Suitably, the fan controls will involve supply fans (e.g., one or more fans in parallel) that work based on a constant pressure method. Suitably, any time the zone damper changes positon, the supply fans swill adjust to the pre-set pressure point using the variable frequency drive. 
         [0059]    As shown in  FIGS. 2 through 4 , the venting box  1300  suitably features at least one return air opening  1360  on its floor. In use, the return air opening  1360  permits stagnant air from inside the space (not shown) (e.g., a building) to be drawn into the venting box  1300  and exhausted to the ambient via the exhaust vent  1370 , which includes a back draft damper  1371  and corresponding louvers  1372 . Suitably, the driving force for pulling return air from the inside of the space (not shown) is an exhaust fan  1365  and motor assay  1366  that is positioned adjacent to the return air opening  1360 . In a preferred embodiment, the venting box  1300  suitably features access doors  1367  and  1368  so that the damper,  1371 , the exhaust fan  1365  and motor  1366  may be properly accessed for maintenance. 
         [0060]      FIG. 5  is an air flow diagram for the VRF  1000 . Suitably, the outside air dampers  1310  allow fresh outside air into a building to meet code requirements. As shown, the air is filtered by the filter bank  1340 . In one embodiment, one or more fans ( 1351 ,  FIGS. 1 through 4 ) may be used for delivering the same air to all zones inside of a building, whereby the design can be more than 50% efficient than systems that require one fan per cooling space. In a preferred embodiment, the filter air is provided through a cooling unit or coil ( 1390 ), one coil  1390  per zone to be cooled. As shown, each space being serviced by the cooling units  1390  has its own coil in the cooling unit and all drain pans associated with each zone are manifolded together to create a single drain connection from the unit. This consolidation of drain pans is preferably done without mixing air paths for each cooled zone. In one embodiment, the system  1300  has an economizer to use outside air to cool inside air if the outside air temperature is lower than the inside air temperature. 
         [0061]      FIG. 6  a dimensioned plan view of the preferred embodiment the VRF.  FIG. 7  is a dimensioned side view of the preferred embodiment of the VRF system.  FIG. 8  is a dimensioned end wall view of the preferred embodiment of the VRF system.  FIG. 9 through 11  are respectively a dimensioned plan view, a dimensioned side view, and a dimensioned end wall view of an alternate embodiment the VRF. In those figures, the system may feature the following components with numerals that correspond to the numerals in the figures:
   ( 1 ) an outside air damper;   ( 2 ) a louver;   ( 3 ) an supply air (SA) opening;   ( 4 ) Mitsubishi R2 series fan;   ( 5 ) a filter bank;   ( 6 ) an access door;   ( 7 ) an access door;   ( 8 ) a filter gauge;   ( 9 ) a supply fan and motor assembly;   ( 10 ) an access door;   ( 11 ) N/A;   ( 12 ) a drain connection;   ( 13 ) a removable panel;   ( 14 ) a control enclosure;   ( 15 ) a coil;   ( 16 ) n/a;   ( 17 ) n/a;   ( 18 ) a controller;   ( 19 ) a single source power panel;   ( 20 ) a SF &amp; exhaust fan (EF) VFDs;   ( 21 ) a backdraft damper with exhaust air (EA) louver;   ( 22 ) walk away grating;   ( 23 ) exhaust fan and motor assembly;   ( 24 ) lifting lugs; p 0  ( 25 ) N/A   ( 26 ) access door; and,   ( 27 ) access door.   
 
         [0088]    As discussed above, the VRF system suitably features a base  1100 .  FIG. 12  is a diagram of the base of the VRF system.  FIG. 13  illustrates the installation of the VRF system. As shown in those figures, the base  1000  may be suitably installed on a roof curb via a curb mounting that extends from the base  1000 . 
         [0089]    Although the method and apparatus is described above in terms of various exemplary embodiments and implementations, it should be is understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead might be applied, alone or in various combinations, to one or more of the other embodiments of the disclosed method and apparatus, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus the breadth and scope of the claimed invention should not be limited by any of the above-described embodiments. 
         [0090]    Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open-ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like, the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof, the terms “a” or “an” should be read as meaning “at least one,” “one or more,” or the like, and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that might be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future. 
         [0091]    The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases might be absent. The use of the term “assembly” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether control logic or other components, might be combined in a single package or separately maintained and might further be distributed across multiple locations. 
         [0092]    Additionally, the various embodiments set forth herein are described in terms of exemplary block diagrams, flow charts and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives might be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular architecture or configuration. 
         [0093]    All original claims submitted with this specification are incorporated by reference in their entirety as if fully set forth herein.