Patent Application
20190301758
This disclosure generally relates to a heating, ventilating, and/or air-conditioning (HVAC) system, and more particularly, to a variable air volume (VAV) multi-zone system having separate and independent hot and cold deck dampers that are individually controllable for each zone.
HVAC systems may supply conditioned air to one or more zones. These systems may increase indoor air quality by providing clean, fresh outside air while removing old, recirculated stale air. Many mechanical systems for buildings and particularly schools may have been built using an air distribution system known as a multi-zone air handling system, which is a type of HVAC system. The multi-zone air handling system provides individual zone control for spaces, such as classrooms, by mixing hot deck air from a heating coil and cold deck air from a cooling coil to maintain space temperature.
The multi-zone air handling system, however, is inefficient. First, when the space temperature is satisfied for both heating and cooling, the zone dampers for that space mix hot deck air and cold deck air to provide no change in air temperature to the space. That is, unless a space uses full heating or full cooling, the mixing of hot deck air and cold deck air is continuously wasting energy. Second, the typical multi-zone air handling system is be a constant volume air reheat system. The system supplies the same volume of air regardless of individual zone heating or cooling demands. This constant volume system wastes fan horsepower if the zone is not requiring full heating or cooling, which may be ninety-five percent (95%) of the time. Additionally, some city and/or state codes may have outlawed traditional multi zone systems.
The present disclosure provides a VAV multi-zone system and method thereof that solves each of the described concerns. The system advantageously reduces the use of continuously wasted energy and supplies a variable air volume of air while satisfying individual heating and/or cooling for those zones. Other benefits and advantages will become clear from the disclosure provided herein and those advantages provided above are for illustration.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the DESCRIPTION OF THE DISCLOSURE. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
In accordance with one aspect of the present disclosure, an apparatus for controlling a heating, ventilating, and air conditioning system for a plurality of zones is provided. The apparatus may include an airflow source providing variable airflow. In addition, the apparatus may include a hot deck partitioned by a plurality of hot deck dampers, each hot deck damper corresponding to a zone within the plurality of zones and a cool deck partitioned by a plurality of cold deck dampers. Each cold deck damper may correspond to a zone within the plurality of zones. The apparatus may also include a plurality of thermostat devices measuring a temperatures within the plurality of zones. The apparatus may include a controller in communication with the airflow source, plurality of hot deck dampers and cold deck dampers, and the plurality of thermostat devices. The controller may open the hot deck damper and close the cold deck damper of a zone within the plurality of zones when a temperature of the zone is below a predetermined value of a temperature set point for the zone. In addition, the controller may close the hot deck damper and open the cold deck damper of a zone within the plurality of zones when a temperature of the zone is above a predetermined value of a temperature set point for the zone. The controller may also maintain a pressure by adjusting the variable airflow of the airflow source.
In accordance with another aspect of the present disclosure, a method of controlling the temperature for a plurality of zones with airflow is provided. The method may include partitioning a hot deck and cool deck with damper section zones with each damper section zone corresponding to a zone within the plurality of zones. In addition, the method may include modulating a hot and cold deck damper associated with each damper section zone based on a temperature set point of each zone. The method may also include maintaining a pressure by adjusting the airflow based on the modulated hot and cold deck dampers for each damper section zone.
In accordance with yet another aspect of the present disclosure, a temperature control system for a plurality of zones is provided. The system may include an airflow source providing airflow to the plurality of zones and an airflow measurement device measuring the airflow to the plurality of zones. In addition, the system may include a plurality of thermostat devices measuring a temperature within each zone of the plurality of zones and a heating device heating the airflow and a cooling device cooling the airflow, wherein the heating and cooling device are partitioned by damper section zones with each damper section zone corresponding to a zone within the plurality of zones and having a hot and cold deck damper. The system may also include a controller in communication with the airflow measurement device and the plurality of thermostats to adjust the airflow and the temperature within each zone through the airflow source, and hot and cold deck dampers for each damper section zone.
The novel features believed to be characteristic of the disclosure are set forth in the appended claims. In the descriptions that follow, like parts are marked throughout the specification and drawings with the same numerals, respectively. The drawing figures are not necessarily drawn to scale and certain figures may be shown in exaggerated or generalized form in the interest of clarity and conciseness. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein:
The foregoing description is provided to enable any person skilled in the relevant art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the relevant art, and generic principles defined herein may be applied to other embodiments. Thus, the claims are not intended to be limited to the embodiments shown and described herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically stated, but rather “one or more.” All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the relevant art are expressly incorporated herein by reference and intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.
This disclosure relates to a HVAC system. More particularly, this disclosure describes a VAV multi-zone system that removes and replaces cooperating mixing dampers on a typical multi-zone unit with two separate and independent hot and cold deck dampers for each zone. In an illustrative embodiment, the VAV multi-zone system may partition a hot deck and cool deck with damper section zones. Each damper section zone may corresponding to a zone within a plurality of zones that the HVAC system services. A controller within the VAV system may modulate a hot and cold deck damper associated with each damper section zone based on a temperature set point of each zone. The temperature set point may be established through a thermostat located in each zone. A pressure may be maintained by adjusting fan speed/airflow based on the modulated hot and cold deck dampers for the damper section zones.
Numerous other modifications or configurations to the VAV system will become apparent from the description provided below. For example, return fans may be implemented into the VAV system to provide return airflow from the facility. Advantageously, the VAV multi-zone system minimizes or eliminates hot and cold deck air mixing. Energy waste is reduced and may be partially or completely eliminated. With independent dampers, only cooled air flow may be supplied to the space when cool air is requested and similarly, only heated air flow may be supplied to the space when heated air is requested. Energy savings may be increased up to twenty-one percent (21%) by converting a constant air volume (CAV) multi-zone system to the VAV multi-zone system. Other advantages will become apparent from the description provided below.
The present disclosure will depict the VAV multi-zone system in
Turning to
Previous multizone systems allowed control of heating and/or cooling of individual zones. These systems, however, placed hot decks 104 and cold decks 112 in separate multi zone air plenums in which airflow from an airflow source split into two paths, one for heating and the other for cooling. At each entry point into a zone duct, the separate cold deck 112 and hot deck 104 would be combined at the multi zone discharge into a single zone duct. These zone ducts allowed greater flexibility in satisfying multiple zones, therefore providing individual zone temperature control. Nevertheless, mixing occurred from the airflow coming out of the separate cold deck 112 and hot deck 104 at all times wasting energy.
As differentiated, the now described VAV multi-zone system 100 maintains a single hot deck 104 and cold deck 112 at a centralized location. The hot deck 104 and cold deck 112 of the system 100 may be partitioned through a plurality of damper section zones, with each damper section zone corresponding to a zone within the plurality of zones of the building. The hot deck 104, as shown in
The hot deck 104 may be heated through different systems. In one non-limiting example, steam may be used to provide heat to the hot deck 104. The steam may be provided from a boiler that may be connected to the VAV multi-zone system 100. In another non-limiting example, the hot deck 104 may be heated through heating coils. These heating coils may convert electrical energy into heat. By passing electric current through resistors, the coils may begin to heat. As shown in
While not shown, a digital direct controller 120 may be in communication with the hot deck 104. The controller 120 may be able to control the hot deck temperature 106 and the hot water return 108 to regulate the flow of heat to the hot deck 104. Furthermore, the controller 120 may adjust the temperature setting of the boiler to provide adequate heat to the hot deck 104. For the non-limiting example of using electric coils, the controller 120 may shut off or turn on the heating coil to produce heat for the hot deck 104.
The hot deck 104 is separated from the cold deck 112. They are entirely independent of one another such that they are located at different locations or areas of the multi zone unit. In one example, the hot deck 104 and cold deck 112 may be separated by a channel or barrier that prevents the mixing of hot and cold air.
The cold deck 112 may be connected to at least one cold damper 110. Similarly, the cold damper 110 may provide a valve or plate that stops or regulates the flow of air inside a zone duct. The cold deck damper 110 may be used to cut off or turn on cooling to a zone, or to regulate the temperature within that zone.
As will be shown, the cold deck dampers 110 may correspond to, or be associated with, a hot deck damper 102 for each zone within the plurality of zones. A cold deck damper 110 along with a hot deck damper 102 may be connected together to provide heating, cooling and ventilation to each zone. These associations form zone damper section zones.
The cold deck 112 incorporates cooling coils to cool air that passes through them. These cooling coils require chilled water provide by a chiller which in turn, requires electrical energy. In another non-limiting example, the cold deck 112 may be chilled water coils, refrigerant or direct expansion (DX) coils. Cooled liquid may flow through pipes in a building and pass through coils in air handlers, fan-coil units, or other systems.
As shown in
By separating the hot deck dampers 102 from the cold deck dampers 110, the mixing of hot and cold deck air may be significantly reduced. When a zone within the plurality of zones calls for cooling, that zones hot deck damper 102 is closed and the cold deck damper 110 is opened to supply as much cooling as required to meet the zone or space cooling. Oppositely, and upon a call for heat to a zone within the plurality of zones, that zones cold deck damper 110 may close and the hot deck damper 102 will open. The modulated or adjusted cold deck damper 110 and hot deck damper 102 of each zone damper section is based on a temperature set point of each zone. When neither heating nor cooling is required the hot deck damper 102 and the cold deck damper 110 can be in a minimum open position to provide occupancy ventilation airflow to the zone.
As described above, a temperature set point for a zone may be set to either heat or cool the zone. A predetermined value may be used before heating or cooling is actuated. For example, the system 100 may open the hot deck damper 102 and close the cold deck damper 110 for a zone within the plurality of zones when a temperature of the zone is below the predetermined value of the temperature set point for the zone. The deviation from setpoint may be one degree Fahrenheit (1° F.).
Similarly, the system 100 may close the hot deck damper 102 and open the cold deck damper 110 for a zone within the plurality of zones when a temperature of the zone is above a predetermined value of a temperature set point for the zone. The deviation from setpoint may also be one degree Fahrenheit (1° F.).
As shown above, the direct digital controller 120 may be used to control the temperature of the hot deck 104, the cold deck 112, the cold deck dampers 110 and hot deck dampers 102. The controller 120 may also be used to adjust a pressure within the VAV multi-zone system 100. As the hot deck dampers 102 and cold deck dampers 110 are modulated to provide individual comfort to each of the zones within the plurality of zones, the pressure within the system 100 may change. Air flowing through the system 100 may change because of the position of those dampers 102 and 110.
To achieve equal pressurization, which includes maintaining the pressure that may have been adjusting by the modifications to the dampers 102 and 110, a fan speed of the airflow source may be varied to meet an expelled air flow rate for each zone of the plurality of zones. A plenum pressure transducer 122 is provided within the VAV multi-zone system 100 to measure the pressure. In one embodiment, the transducer 122 is placed in a plenum space of the VAV multi-zone system 100.
The plenum pressure transducer 122 may include, but is not limited to, a capacitive pressure transducer, digital output pressure transducer, voltage/current output pressure transducer, and the like. The transducer 122 may convert pressure into an analog electrical signal such that it may be used to control the fan array 124. This may be achieved by control of the fan array speed based on the pressure, which then produces an electrical resistance change proportional to the pressure.
By receiving the information from the plenum pressure transducer 122, the direct digital controller 120 may maintain a pressure by adjusting the fan speed/airflow based on the modulated cold deck dampers 110 and hot deck dampers 102 for each damper section zone. In one embodiment, the controller 120 may adjust the fan array 124, or airflow source, that leads to the hot deck 104 and cold deck 112. The fan array 124 may provide a variable airflow. Advantageously, by having a variable airflow from the fan array 124, energy savings and reduced wear may be realized.
In previous implementations of VAV systems, a VAV terminal unit, often called a VAV box, may have been used to provide zone-level flow control. The VAV box may have been a calibrated air damper with an automatic actuator, which may have been controlled by the direct digital controller 120. The VAV multi-zone system 100 may remove the VAV box, yet still provide the same or better functionalities.
The fan array 124 may be a critical component of the VAV multi-zone system 100. Without proper and rapid flow rate control, the system's ductwork, or its sealing, may be damaged by over pressurization. In the cooling mode, as the temperature in the zone is satisfied, the system 100 through the direct digital controller 120 may close the cold deck dampers 110 to limit the flow of cool air into the zone. As the temperature increases in the zone, the cold deck dampers 110 may open to bring the temperature back down. The fan array 124 may maintain a constant static pressure in the air plenum at PT 122. As the cold deck damper 110 closes, the fan array 124 may be given an indication to slow down based on that specific zone and restricted amount of airflow going into the zone supply duct. As the cold damper 110 opens, the fan array 124 may speed up and allow more air flow into the duct, maintaining a constant static pressure at PT 122. The same may be true when the hot deck dampers 102 are opened and closed for each zone.
As the plurality of hot deck dampers 102 and cold deck dampers 110 open and close, airflow may change, and pressure which may be determined by the plenum pressure transducer 122 may rise and fall. The speed of the fan array 124 may be adjusted or modulated to meet the design cooling or heating air flow rate on each zone using the fixed pressure at PT 122.
Systems as shown in the VAV multi-zone system 100 may provide cool air in one zone duct through the cold deck 112 and the cold deck dampers 110 and hot air in a second zone duct through the hot deck 104 and hot deck dampers 102 to a specific zone within the plurality of zones. Thus, a single hot deck 104 and cold deck 112 may be used that are independent of one another. The cold deck dampers 110 and hot deck dampers 102 may be able to let air flow there through partially or wholly, or completely cut the airflow off to a specific zone.
Continuing with the VAV multi-zone system 100 of
Continuing with
Outside air 128 may enter the VAV multi-zone system 100 through a roof or sidewall vent inlet that collects air from a clean outside location. An outside air monitor/sensor 130 may be used to determine how much outside air 128 should enter into the facility. An outside air damper 132 may be used to regulate how much outside air 128 is taken in. The fan array 124 may draw the outside air 128 into the VAV multi-zone system 100. The airflow may be pulled into the system through the filter 126. The air may mix with the return air, and then may be dispersed evenly throughout the building via the supply duct zones. The return air dampers 138 may be partially or wholly shut when air is being drawn from the outside air 128.
Adding fresh air to the VAV multi-zone system 100 may accomplish three (3) primary indoor air quality goals: (1) pressurize the facility; (2) increase indoor air quality by diluting polluted or stale indoor air, and (3) remove carbon dioxide volatile organic compounds and other contaminants. In one embodiment, the ducting taking the outside air 128 may include a volume damper to control the volume of the airflow. Another option for the system 100 may be a motorized shutoff damper that seals off the duct from the outside when the fan array 124 motor is not running. Insulation may be added to the outside of the ducting supplying the outside air 128 to contain the heat or cold from entering the facility.
Since the fresh air enters the duct before the fan array 124, the volume of return air 138 being returned to the facility may be less than the supply airflow the VAV multi-zone system 100 delivers into the facility. As the supply air exceeds return air 138, a positive pressure may be maintained in the facility when the fan array 124 is in operation. Positive pressure may reduce infiltration of outside air 128 from undesirable locations and prevent duct irritants and other pollutants from entering the facility. This control may reduce the heat loss or gain sufficient to offset the cost of heating or cooling the outside air.
When the return air 134 from within the facility is to be recirculated, the outside air damper 132 may be partially or fully shut with the return air dampers 138 partially or fully opened. Airflow may be drawn to the fan array 124 from the return air dampers 138 and thus through the return air 134. Return fans 136 may also be activated to further draw in air already existing within the facility.
The relief exhaust 140 of the VAV multi-zone system 100 may expel air to relieve pressure within the system 100. The relief exhaust 140 is typically outside the facility. This may be used to relieve air within the facility. By closing the return air dampers 138 and opening the relief exhaust dampers 144, air may be drawn from the facility. In one instance, outside air 128 may also be pulled from the outside, thus fresh, clean air may be brought in and old, stale air expelled. The relief damper actuator 142 may be used to relieve return air through the relief exhaust 140 via the relief exhaust damper 144. The damper actuator 142 may interact with the direct digital controller 120.
Each of the dampers including the hot deck dampers 102 and the cold deck dampers 110 may provide low or no leakage with each damper 102. They may use motorized actuators for zone heating and cooling demands. As shown, each damper section zone 202 may provide airflow to a particular zone within the facility. A hot deck damper 102 may correspond with a cold deck damper 110 to form the damper section zone 202. The dampers 102 and 110 are independent and separate from one another, however, they may be adjusted or modulated together depending on the zone's request.
The hot deck damper impedance actuators may move the hot deck dampers 102 for each damper section zone 202 independently of one another. That is, a plurality of impedance actuators may exist for each zone 202 for the hot deck 104. The actuators may open, partially open or close the dampers 102.
The actuators may be automatically sized to operate their appropriate loads with sufficient reserve power to provide smooth modulating action or two-position action and tight close-off. The actuators may provide: two-position, floating, or analog signal control, or bus control to match the direct digital controller 120 output. The actuators may provide a power failure return type where the dampers 102 and 110 may be required to fail to a safe position. The hot deck damper 102 may be coupled to the hot deck 104 through a flanged connection 204, or other coupling.
The damper section zones 202 may also have a corresponding cold deck damper 110. Similarly, cold deck damper actuators 208 associated with the cold deck damper 110 may be separate and independent of one another in each of the zones 202. The actuators 208 may be used to open, partially open or close the dampers 110. The cold deck 112 may be connected to the cold deck dampers 110 and allow airflow to pass through or prevent the airflow.
The actuators 208 for the cold deck dampers 110 may similarly provide: two-position, floating, or analog signal control, or bus control as may be required to match the direct digital controller 120 output. The actuators 208 may provide a power failure return type where valves or the dampers 110 may fail to a safe position. The cold deck dampers 110 may be tied or coupled to the cold deck 112 through flanges 206, or other coupling.
Continuing with
For each zone, when there is no call for heating or cooling, the hot deck damper 102 and the cold deck damper 110 may go to a minimum position, which may be adjustable. The minimum airflow through a zone which is not calling for heating or cooling may be set up with an air balancer. In one non-limiting example, approximately ten percent (10%) mixing of hot deck and cold deck air may be used. This may provide ventilation at the balance point of a zone when the heat loss and heat gain for the room are equal.
As the zone becomes satisfied with heat, the hot deck damper 102 may close. For each zone, when there is a call for cooling, the hot deck damper 102 may remain closed and the cold deck damper 110 may modulate to open to maintain the zone cooling demand. As provided before, the predetermined value of the temperature set point may be used to modulate the dampers 102 and/or 110.
Initial set up for the VAV multi-zone system 100 may include positioning all cold deck dampers 110 to full open, which may be performed through the actuators 208. The multi-zone unit plenum fan array 124 may be set to meet the design cooling air flow rate on each zone. The plenum box pressure of the system 100, which may be used to meet the design cooling and/or heating airflow rate on each zone, may use the adjustable plenum pressure transducer 122 to maintain the pressure within the system 100. This may be performed through the direct digital controller 120.
After the VAV multi-zone system 100 is setup, the system 100 may allow the independent hot deck dampers 102 and the cold deck dampers 110 to modulate based on each zones call for heating and cooling. The fan array 124 along with the plenum pressure transducer 122 may be used to modulate or adjust the speed of the fan array 124 through the variable frequency drive to maintain the pressure set point, which may be adjustable.
Continuing with the damper section zones 202 of
Continuing with the damper section zones 202 of
The digital direct controller 120 may include an interface 1302. The interface 1302 may be integral with the controller 120 housing, but in some instances, may be remote from the controller 120, such as when using an interface 1302 of a smart phone, tablet computer, personal computer, laptop, or the like. The interface 1302, which may be operatively coupled to the controller 120, may display the determined recommended setting for the hot deck dampers 102 and cold deck dampers 110.
The digital direct controller 120 may include a processor 1304 and memory 1306. The memory 1306 may be operatively coupled to the processor 1304. The memory 1306 may store program instructions that when executed by the processor 1304, causes the processor to perform processes.
The controller 120 may include a wireline or wireless communications port to communicate with a component 1308. The components 1308 may include, but are not limited to one or more HVAC components, a system of ductwork and air vents, thermostats, or any other component described above.
At block 1402, the direct digital controller 120 may measure a temperature and airflow of each zone within the plurality of zones. This may include using a thermostat within each zone. The pressure transducer 122, described earlier, may be used to determine the pressure within the system 100.
At block 1404, the hot deck dampers 102 and the cold deck dampers 110, making a damper section zone 220, may be modulated based on the previous measurements. These may be modulated based on a temperature set point of each zone.
In a non-limiting example, upon a zone within the plurality of zones call for cooling, a damper section zone having the hot deck damper 102 closed and the cold deck damper 110 opened may supply as much cooling as required to meet the zone or space cooling. Oppositely, and upon a call for heat to a zone within the plurality of zones, the damper section zone may close the cold deck damper 110 and open the hot deck damper 102. The modulated or adjusted cold deck damper 110 and hot deck damper 102 of each damper section zone may be based on a temperature set point of each zone and a predetermined value as previously described.
At block 1406, the pressure may be maintained within the VAV multi-zone system 100 by adjusting the airflow based on the modulated hot deck dampers 102 and the cold deck dampers 110 for the plurality of zones. To achieve equal pressurization, which includes maintaining the pressure that may have been adjusted by the modifications to the dampers 102 and 110, a fan speed of the airflow source may be varied to meet an expelled air flow rate for each zone of the plurality of zones. A plenum pressure transducer 122 may be provided within the VAV multi-zone system 100 to measure the pressure. In one embodiment, the transducer 122 may be placed in a plenum space of the VAV multi-zone system 100. The processes may end at block 1408.
The foregoing description is provided to enable any person skilled in the relevant art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the relevant art, and generic principles defined herein may be applied to other embodiments. Thus, the claims are not intended to be limited to the embodiments shown and described herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically stated, but rather “one or more.” All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the relevant art are expressly incorporated herein by reference and intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.
This disclosure claims priority to U.S. Provisional Patent Application Ser. No. 62/652,073, titled “Variable Air Volume Multi Zone System”, which was filed on Apr. 3, 2018 and is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62652073 | Apr 2018 | US |
