Multi-Zone Variable Refrigerant Flow Heating/Cooling Unit

This application is a continuation of co-pending U.S. patent application Ser. No. 18/154,971 filed Jan. 16, 2023, which is a continuation of U.S. patent application Ser. No. 17/143,802 filed Jan. 7, 2021, now U.S. Pat. No. 11,555,618, which is a continuation of U.S. patent application Ser. No. 16/148,293 filed Oct. 1, 2018, now U.S. Pat. No. 10,890,341, which is a continuation of U.S. patent application Ser. No. 14/752,346 filed Jun. 26, 2015, now U.S. Pat. No. 10,088,178 entitled “Centralized, Multi-Zone Variable Refrigerant Flow Heating/Cooling Unit,” which claims the benefit of U.S. Provisional Application No. 62/157,109 filed May 5, 2015, entitled, “Centralized, Multi-Zone Variable Refrigerant Flow Heating/Cooling System,” the contents of both of which are incorporated herein by reference in their entirety.

Conventional multi-zone (“MZ”) air conditioning units are typically constant volume systems that maintain room air changes, space temperature, and relative humidity with a high degree of precision. A basic MZ unit can include a supply air blower segment, a coil segment and discharge air elements. Other elements, such as filters, air mixing boxes, access, and full economizer with a return/exhaust air blower, can be offered to customize a unit for a particular application. A unit discharge can be available with dampers or dual-duct openings, either in horizontal or up-blast configurations.

MZ systems often use zone dampers, located at the air unit in a particular space, to mix heated air from a heating coil and chilled air from a chilled water coil to regulate the air temperature for a space, or zone. The zone dampers, mixing air in proportions, keep the flow of mixed air to each zone approximately constant. A zone thermostat controls each pair of zone dampers. Zones are typically designed to have a separate duct that extends from the air-handling unit to the space. The MZ system is best suited for offices, schools and other similar buildings where a relatively small space requires independent zone thermostatic control.

It is with respect to these and other considerations that the disclosure made herein is presented.

The following detailed description is directed to technologies for a multi-zone, variable refrigerant flow heating and/or cooling unit (“MZ VRF unit”). In some examples, the MZ VRF unit may provide heating and/or cooling to two or more zones in a structure. In some examples, a structure may include a building such as, but not limited to, a house, an office, and a warehouse. In some configurations, the MZ VRF unit may be configured to provide heated or cooled air to the one or more zones through the use of a combination of a variable refrigerant flow cooling/heating unit (“VRF unit”) and a mode control unit.

In implementations, the VRF unit may be configured to deliver refrigerant flow at various rates depending on, among other possibilities, the current cooling or heating loads supplied by the MZ VRF unit. In implementations, the mode control unit may supply refrigerant from the VRF unit to two or more evaporating coils (“coils”) through a thermal or thermostatic expansion valve. The coils may allow heat transfer between supply air from a supply fan and the refrigerant in the coils to reduce the temperature of the supply air for various zones in a cooling mode of operation. The reduced temperature supply air may then enter a duct for each of the various zones. A return air outlet from the zones may enter the MZ VRF unit and either be recirculated as supply air or exhausted, or various combinations of each.

In some examples, each zone supplied by the MZ VRF unit may be cooled or heated independently of each other. In implementations, the mode control unit may receive a heating and/or cooling medium from the VRF unit. The mode control unit may be configured to deliver the heating medium to the coils for one or more zones supplied by the unit and the cooling medium to the coils for one or more other zones. The heating or cooling of the one or more zones may be changed from either cooling to heating or heating to cooling depending on the needs of the particular zone.

In some examples, the presently disclosed subject matter includes an air conditioning unit. The air conditioning unit can include a housing. The housing can include a supply air inlet operable to provide supply air to a supply fan, an exhaust air outlet operable to receive air from a return/exhaust fan, a plurality of zone duct attachments operable to provide air from the air conditioning unit to a plurality of zones, and a return air attachment for receiving exhaust air from the plurality of zones.

The housing can have enclosed therein a variable refrigerant flow cooling/heating unit operable to provide a cooling or heating medium for a unit of each of the plurality of zones, the unit operable to cool or heat the supply air to its respective zone of the plurality of zones, and a mode control unit operable to switch a unit of each of the plurality of zones from a cooling mode to a heating mode.

These and various other features will be apparent from a reading of the following Detailed Description and a review of the associated drawings.

This Summary is provided to introduce a selection of technologies in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended that this Summary be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

Embodiments of the disclosure presented herein encompass technologies for a multi-zone, variable refrigerant flow unit, whereby a variable refrigerant flow system is incorporated with a multi-zone unit as a packaged unit or system. The MZ VRF unit may include a cooling/heating unit that provides a cooling and/or heating medium for heating and/or cooling two or more zones. A mode control unit may control the heating or cooling medium flow to one or more coils. Air provided by a supply fan is either cooled or heated and provided from the MZ VRF unit to the two or more zones. These and other aspects are described in more detail in reference to various figures.

By utilizing VRF technology in a multi-zone layout, in some implementations, one can take advantage of the ability to simultaneously provide heating and cooling to individual zones without the use of additional mediums of heat (hot water, steam, gas, or electric) and without adding heating or cooling to other zones that do not need it. In some implementations, a triple deck or three pipe multi-zone unit may be used.

Various implementations of the presently disclosed subject matter may provide various benefits. For example, in some examples, an MZ VRF unit of the presently disclosed subject matter may help to consolidate refrigerant piping and electrical wiring into the MZ VRF unit. Conventional VRF installations typically have a condensing section installed in a central location with suction and liquid lines “spidering” out to the individual room units serving the spaces. As a result, these installations may have a higher refrigerant charge need as compared to an MZ VRF unit of the presently disclosed subject matter. Some industries, such as supermarkets, have rejected air conditioning technologies that use dispersed refrigerant lines.

Combining and consolidating the VRF into a single multi-zone unit could also reduce the amount of copper, not only in refrigerant line runs, but also in the electric wiring. Instead of providing power to indoor modules all over a building, a single, large power feed could be provided to an MZ VRF unit and the power internally distributed in the unit itself. This could also cut down on building electrical costs for large and multiple VRF installations where multiple condensers and indoor modules could take up many electrical panel boards. Instead of routing piping throughout a building, refrigerant piping could be isolated from the airstream and the systems piped in a manner that would meet some refrigeration codes in some states and cities.

Another benefit of some implementations of an MZ VRF unit is that a primary amount of maintenance may be performed at the MZ VRF unit and out of the space, or zones, being serviced by the MZ VRF unit. A service provider may not have to be in a space to perform maintenance, which may disrupt occupants of the space.

An additional benefit of some implementations of an MZ VRF unit is a better ability to comply with ASHRAE standards, including Standard 15. Standard 15 generally defines an allowable amount of refrigerant that may be present in a particular space. The allowable amount of refrigerant is calculated using factors such as the size of the space and amount of refrigerant that may be dispersed into the space upon a catastrophic event such as a leak. In some examples, the MZ VRF unit contains the refrigerant within the housing and does not enter the space, thereby making it easier to comply with various standards, including the ASHRAE standards.

A still further benefit of some implementations of an MZ VRF unit may be a reduction or elimination of condensate pumps. In air conditioning systems in which refrigerant lines run through a building, depending on the environmental conditions around the lines, condensate (water) may form on the lines. If not removed, the condensate may drop onto interior surfaces of the building, possibly resulting in damage to the particular space. To prevent damage, condensate collection systems and pumps may be used to collect the condensate and pump the condensate outside of the space. In some implementations, because the refrigerant lines are contained within the housing of an MZ VRF unit, condensate formation and collection on refrigerant lines within an air conditioned space is avoided.

In the following detailed description, references are made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments or examples. Referring now to the drawings, aspects of an exemplary operating environment and some example implementations provided herein will be described.

is a system diagram showing one an example MZ VRF unit. The MZ VRF unitmay be enclosed within a housing. The housingmay fully or partially enclose various components of the MZ VRF unit. The housingmay include one or more attachment or installation components (not shown) that allow the MZ VRF unitto be installed in various locations. In one configuration, the MZ VRF unitmay be operated in conjunction with other MZ VRF units.

The MZ VRF unitmay include a VRF cooling/heating unit. The VRF cooling/heating unitmay be configured to provide a heating or cooling medium to various components of the MZ VRF unit. In some examples, the cooling medium may include, but is not limited to, refrigerant or chilled water. In other examples, the heating medium may include, but is not limited to, fluids heated by gas heat or electric heat, hot water, steam, or heat recovered from various parts of the MZ VRF unit. It should be noted the presently disclosed subject matter is not limited to any particular type of cooling or heating medium.

To provide a cooling medium, the VRF cooling/heating unitmay include a cooling component. In some examples, the cooling componentmay be a source of chilled water. In other examples, the cooling componentmay be a refrigeration unit capable of receiving a compressible refrigerant such as R114 or R12. The presently disclosed subject matter is not limited to any particular type of configuration.

To provide a heating medium, the VRF cooling/heating unitmay include a heating component. The heating componentmay be an apparatus or system configured to provide a heating medium. As noted above, some examples of a heating medium may include, but are not limited to, fluids heated by gas heat or electric heat, hot water, steam, or heat recovered from various parts of the MZ VRF unit. Therefore, the heating componentmay be a gas or electric system configured to increase the temperature of a fluid that acts as the heating medium. In other examples, the heating componentmay be a receptacle for receiving heated water, steam, or may be a heater configured to produce the heated water or steam. These and other implementations are merely illustrative and are not meant to limit the scope of the presently disclosed subject matter.

To circulate either the cooling medium or the heating medium from the cooling componentor the heating component, respectively, the VRF cooling/heating unitmay include a cooling pumpand a heating pump. The cooling pumpmay be configured to receive the cooling medium and provide the positive pressure necessary to move the cooling medium through various components of the MZ VRF unit. It should be noted that in some instances, such as the case of an HVAC system utilizing a compressible refrigerant, the cooling pumpmay be integrated into the cooling componentas a compressor to compress the refrigerant. It should be further noted that the presently disclosed subject matter does not require that the cooling pumpand the heating pumpto be separate components, as some implementations may use the same pump to perform both functions.

In some configurations, it may be desirable to vary the flow of the cooling medium through the MZ VRF unit. Having a variable flow may allow for various benefits. For example, using variable flow may allow for continuous operation at an optimal speed of the cooling pump(which may be a compressor in a system using compressible refrigerant) rather than an on/off configuration. Turning the cooling pumpon and off, especially when done in an excessive manner, can increase the wear and tear on the equipment as well as require the use of starting current to start up the system, which may be significant depending on the particular configuration.

To provide for varying cooling flow rate, the VRF cooling/heating unitmay include an inverter. In some examples, the invertermay be configured to receive an electrical input at one frequency and provide an electrical output at a plurality of second frequencies. The output of the inverteris used to power the cooling pump. The frequency of the output of the invertercontrols the speed of the cooling pump. An increase in frequency can increase the speed (and thus flow rate) of the cooling pump.

Likewise, a decrease in frequency can decrease the speed (and thus flow rate) of the cooling pump. Thus, the MZ VRF unitmay be configured to receive one or more inputs that chance the output frequency of the inverterto change the flow rate of the cooling medium. The invertermay be also be used to control the flow rate of the heating medium through the changing of the speed of the heating pump.

In some configurations, the VRF cooling/heating unitmay be configured to provide heating, cooling, or a combination of both to various components of the MZ VRF unit. In one implementation, the VRF cooling/heating unitmay include a high-pressure vapor line, a low-pressure vapor line, and a high-pressure liquid line. The high-pressure vapor line, the low-pressure vapor line, and the high-pressure liquid linemay be controlled using a mode control unit.

In some configurations, the mode control unitmay receive the high-pressure vapor line, the low-pressure vapor line, and the high-pressure liquid line. The mode control unitmay be configured to determine the output to zonesupply lineA and zone N supply lineN. As used herein, a “zone” refers to a portion of space to which heated or cooled air is provided. A zone is not limited to any particular configuration, such as one room or one office, as a zone may also be, but is not limited to, one or more floors.

The zonesupply lineA may supply a cooling medium or heating medium to a zone A coilA through thermal expansion valveA. The zone N supply lineN may supply a cooling medium or heating medium to a zone N coilN through thermal expansion valveN. The cooling or heating medium introduced into the zone A coilA may exit through a return lineA to the mode control unit, and eventually to the VRF cooling/heating unitto provide for a closed loop. In a similar manner, the cooling or heating medium introduced into the zone N coilN may exit through a return lineN to the mode control unit, and eventually to the VRF cooling/heating unitto provide for a closed loop.

In some configurations, the VRF cooling/heating untilmay be configured to provide heating and cooling mediums to enable heating and/or cooling of several spaces. As discussed briefly above, in some examples, the VRF cooling/heating unitmay include the high-pressure vapor line, the low-pressure vapor line, and the high-pressure liquid line. It should be noted that other implementations of a VRF cooling/heating unit using more or fewer than the high-pressure vapor line, the low-pressure vapor line, and the high-pressure liquid linemay provide for simultaneous heating and cooling across several spaces. The presently disclosed subject matter is not limited to any particular configuration.

In the “three pipe” VRF cooling/heating unitillustrated in, if a zone unit, such as the zone A coilA or the zone N coilN, is to be operated in a heating mode of operation, the mode control unitwill configure the one or more units to act as condensers. If a zone unit, such as the zone A coilA or the zone N coilN, is to be operated in a cooling mode of operation, the mode control unitwill configure the one or more units to act as evaporators.

In a heating mode of operation, the mode control unitwill act in conjunction with the thermal expansion valveA or the thermal expansion valveN for the particular unit. For example, if the zone A coilA is to be used to heat a space (zone), the mode control unitwould open the zone A unit to the high-pressure vapor lineand the outlet of the zone A coilA to the high-pressure liquid line, causing the zone A coilA to act as a condenser.

In a cooling mode of operation, the mode control unitwill open the input of the zone A coilA to the high-pressure liquid lineand its outlet to the low-pressure vapor line, causing the zone A coilA to act as an evaporator. Similar operations may be provided for the zone N coilN. The heated or cooled air may be provided by a duct to zoneA or a duct to zone NN, as appropriate. Air from the zoneor the zone N may be received from their respective spaces in a zonereturn air ductA or a zone N return air ductN and be combined in return air outlet.

To provide air supply and recirculation, the MZ VRF unitmay include a return/exhaust fanand a supply fan. The return/exhaust fanmay be configured to provide a negative pressure to the zonereturn air ductA or the zone N return air ductN to pull air from their respective zones. The return air may be exhausted as exhaust air using an exhaust damper, a return damper, and an outside air damper. For example, if the exhaust damperis open and the return damperis closed, the exhausted air from the zones will be exhausted as exhaust air.

The return air may also be recirculated back into the zones as well. For example, the exhaust dampermay be partially or fully closed, the return dampermay be partially or fully open, and the outside air dampermay be partially or fully closed. The supply fanwill draw air from the exhaust of the return/exhaust fanand, in some implementations, outside air through the outside air damperto a particular zone.

In some implementations, all of the components of the MZ VRF unitmay be located within the housing. In some examples, the MZ VRF unitmay be transported and installed as a modular unit to heat/cool a building. For example, the MZ VRF unitmay include hoisting eyesA andB to allow a crane or other hoisting equipment to raise or lower the MZ VRF unitinto an appropriate position for operation. In a similar manner, the MZ VRF unitmay also include installation padsA andB to allow the MZ VRF unitto be placed in a particular location.

In some implementations, it may be desirable to use various components to increase the efficiency of an MZ VRF unit. For example, in, the three pipe MZ VRF unitcan increase its efficiency through its dual heating/cooling capabilities, using heat absorbed in one zone to increase the temperature of in another zone.illustrate various technologies that may be implemented for increasing the efficiency of an MZ VRF unit.

is a system diagram showing an MZ VRF unitwith an inlet cooler and an inlet heater. The MZ VRF unitofincludes a housing. Within the housingis contained a VRF cooling/heating unitthat may be configured to provide heating and cooling mediums to enable heating and/or cooling of several spaces. The heating or cooling mediums are provided to a mode control unit. The mode control unitdetermines the particular mediums to be provided to a zone A unitA or a zone N unitN.

The zone A unitA or the zone N unitB cool or heat air provided by a supply fanthrough a duct to zoneA or a duct to zone NN, respectively. The supply fanmay receive air from a return/exhaust fan, which receives air from a return air outletfrom one or more of the zones provided by the duct to zoneA or the duct to zone NN. Air from the one or more of the zones provided by the duct to zoneA or the duct to zone NN may be exhausted through the exhaust air damperor provided, in whole or in part, to the supply fan via return damper.

In some examples, it may be beneficial or necessary to receive air from a source in addition to the air received from the return/exhaust fan. In those examples, the supply fan may also receive outside air through an outside air damper. In some examples, the outside air may be at a temperature that will cause the efficiency of the MZ VRF unitto decrease. Thus, in some examples, the outside air may be preconditioned prior to receipt by the supply fan.

In, the outside air is preconditioned using an inlet coolerand/or an inlet heater. The inlet coolermay be configured to reduce the temperature of the outside air prior to receipt by the supply fan. The inlet heatermay be configured to increase the temperature of the outside air prior to receipt by the supply fan. In some examples, the inlet coolermay be a compressible refrigeration system or a water-based system that received chilled water from various sources. In some examples, the inlet heatermay receive heated water or steam from various sources, or, may be a gas or electric heater.

In some examples, the inlet coolerand/or the inlet heatermay be part of a heat recovery system. For example, return air from a heated zone may be used as a heat source for the inlet heater. In a similar manner, return air from a cooled zone may be used as a refrigeration source for the inlet cooler. In other examples, the inlet cooleror the inlet heatermay be used to increase or decrease the temperature of a heating or cooling medium.

is a system diagram showing an MZ VRF unitwith a hot gas reheater. The MZ VRF unitofincludes a housing. Within the housingis contained a VRF cooling/heating untilthat may be configured to provide heating and cooling mediums to enable heating and/or cooling of several spaces. The heating or cooling mediums are provided to a mode control unit. The mode control unitdetermines the particular mediums to be provided to a zone A unitA or a zone N unitN.

The zone A unitA or the zone N unitB cool or heat air provided by a supply fanthrough a duct to zoneA or a duct to zone NN, respectively. The supply fanmay receive air from a return/exhaust fan, which receives air from a return air outletfrom one or more of the zones provided by the duct to zoneA or the duct to zone NN. Air from the one or more of the zones provided by the duct to zoneA or the duct to zone NN may be exhausted through the exhaust air damperor provided, in whole or in part, to the supply fan via return damper.

In, a hot gas reheat (“HGRH”) coilis provided. The HGRH coilmay provide various benefits. In some examples, the HGRH coilmay reduce the humidity of incoming outside air or the exhaust air from the return/exhaust fan. In other examples, the HGRH coilmay decrease the temperature of the incoming outside air or the exhaust air from the return/exhaust fan.

In some examples, the HGRH coilmay receive as an input a relatively hot high-pressure vapor refrigerant. Refrigerant is passed through the HGRH coil, which is a heat exchanged located downstream of a cooling coil. The hot high pressure vapor leaving the compressor passes through the HGRH coilprior to entering a condenser coil.

is a system diagram showing an MZ VRF unitwith a recovery wheel. The MZ VRF unitofincludes a housing. Within the housingis contained a VRF cooling/heating untilthat may be configured to provide heating and cooling mediums to enable heating and/or cooling of several spaces. The heating or cooling mediums are provided to a mode control unit. The mode control unitdetermines the particular mediums to be provided to a zone A unitA or a zone N unitN.

The zone A unitA or the zone N unitB cool or heat air provided by a supply fanthrough a duct to zoneA or a duct to zone NN, respectively. The supply fanmay receive air from a return/exhaust fan, which receives air from a return air outletfrom one or more of the zones provided by the duct to zoneA or the duct to zone NN. Air from the one or more of the zones provided by the duct to zoneA or the duct to zone NN may be exhausted through the exhaust air damperor provided, in whole or in part, to the supply fan via return damper.

In, a recovery wheel/platemay be used to reclaim energy. In some examples, the recovery wheel/platemay be an enthalpy-type device comprised of a rotating cylinder filled with an air permeable material, which results in a large surface area. As the wheel rotates between the outgoing exhaust air stream and the incoming air stream, energy in the form of heat is received from the higher temperature air stream and released into the colder air stream. Examples materials for wheel construction include, but are not limited to, plastics, polymers, metals (such as aluminum), and various fibers. Desiccants may be used for various reasons, including humidity control and enthalpy exchange. Example desiccant materials may include, but are not limited to, silica gel and molecular sieves.