Patent Grant
11802710
The present invention relates generally to measuring airflow in a predefined area, and more particularly to an article and method for accurately measuring an airflow within a predefined area.
In Heating, Ventilation and Air Conditioning (HVAC) systems air balancing is the process that involves configuring the HVAC system in such a way as to make sure that the air is evenly distributed throughout the building. This is accomplished by making sure that all of the building zones have the correct amount of heat transfer so that all of the components of the HVAC system work in harmony. In general, a Testing, Adjusting and Balancing (TAB) specialist typically performs air and hydronic measurements on the HVAC system and adjusts (i.e. balances) the airflow as required in order to achieve optimal performance of the building environmental equipment. This balancing is usually based upon the design flow values for the building design. Accordingly, it is important to balance the airflow at key locations of the building in order to achieve this optimal performance.
One current method for accomplishing balancing an HVAC system involves using multiple metrics to determine the actual outside airflow (CFMOA) in Cubic Feet Minute (CFM), the actual supply airflow (CFMSA) in Cubic Feet Minute (CFM) and the actual return airflow (CFMRA) in Cubic Feet Minute (CFM). The metrics used to determine these actual values sometimes include the fixed area (AF) for which the airflow is being delivered, the velocity of the airflow at an predetermined fixed area (VAF), the outside air temperature (TOA), the return air temperature (TRA), the mixed air temperature (TMA) and the percentage of outside air relative to the total supply air (OA %). Typically, the TAB specialist measures (or is provided) the airflow in cubic feet per minute for total airflow for the supply fan, the TOA, the TRA and the TMA. Using these values, the TAB specialist then calculates the actual outside airflow (CFMOA) and actual return airflow (CFMRA) for the total airflow for the supply fan using the following formulas:
% Outside Air=((TRA−TMA)/(TRA−TOA))*100;
CFMOA=(% Outside Air)*(VAF*AF);
CFMRA=(VAF*AF)−CFMOA.
Using these values, the TAB specialist adjusts airflows as required to balance the HVAC system.
Unfortunately however, while this particular method for determining the actual airflow values is sufficient for temperature differentials between the outside air temperature (TOA) and the return air temperature (TRA) that are more than 10° F., these current methods produce inaccurate results for temperature differentials between the outside air temperature (TOA) and the return air temperature (TRA) that are less than 10° F. This is undesirable because if the HVAC system is not properly balanced the HVAC system may operate in efficiently, thereby affecting the operating costs of the HVAC system as well as the life expectancy of the HVAC system components and life safety factors based on minimum outdoor air requirements.
An Airflow Measuring System (AMS) for measuring outside airflow and return airflow for an air handling system is provided, wherein the air handling system includes an outside air inlet, a mixed air chamber, a return air inlet, a supply air outlet and a supply fan having a Supply Airflow Station (SAS) with a fixed area, wherein the mixed air chamber is separated from the outside air inlet via a first damper having at least one configurable first damper slat. The AMS includes an Outside Air Temperature Sensor (OATS) located proximate the outside air inlet, a Return Air Temperature Sensor (RATS) located proximate the return air inlet, a Mixed Air Temperature Sensor (MATS) located within the mixed air chamber, a damper actuator, wherein the damper actuator is communicated with the first damper to configure the at least one first damper slat between an open configuration and a closed configuration, and a processing device, wherein the processing device is configured to receive temperature information from the OATS, the RATS and the MATS and Supply Air Output Velocity (SAOV) information from the SAS and is communicated with the damper actuator to configure the at least one first damper slat between an open configuration and a closed configuration. If the Temperature Differential (TD) between the Outside Air (OA) and the Return Air (RA) is greater than or equal to a predetermined TD, the processing device is configured to process the temperature information from the OATS, the RATS and the MATS and Supply Air Output Velocity (SAOV) information from the SAS and calculate a percent of outside airflow into the outside air inlet (CFMOA) value, an actual return airflow (CFMRA) value and a total supply air outflow (CFMSA) value, wherein if the Temperature Differential (TD) between the Outside Air (OA) and the Return Air (RA) is less than the predetermined TD, the processing device is configured to determine the position of the at least one first damper slat and determine the percent of outside airflow into the outside air inlet (CFMOA) value, the actual return airflow (CFMRA) value and the total supply air outflow (CFMSA) value via a predetermined reference table.
An Airflow Measuring System (AMS) for measuring outside airflow and return airflow for an air handling system is provided, wherein the air handling system includes an outside air inlet, a mixed air chamber, a return air inlet, a supply air outlet and a supply fan having a Supply Airflow Station (SAS) with a fixed area, wherein the mixed air chamber is separated from the outside air inlet via a first damper having at least one configurable first damper slat. The AMS includes an Outside Air Temperature Sensor (OATS) located proximate the outside air inlet, a Return Air Temperature Sensor (RATS) located proximate the return air inlet, a Mixed Air Temperature Sensor (MATS) located within the mixed air chamber, a damper actuator, wherein the damper actuator is communicated with the first damper to configure the at least one first damper slat between an open configuration and a closed configuration, and a processing device, wherein the processing device is configured to receive temperature information from the OATS, the RATS and the MATS and Supply Air Output Velocity (SAOV) information from the SAS and is communicated with the damper actuator to configure the at least one first damper slat between an open configuration and a closed configuration. If the Temperature Differential (TD) between the Outside Air (OA) and the Return Air (RA) is greater than or equal to 10° F., the processing device is configured to process the temperature information from the OATS, the RATS and the MATS and Supply Air Output Velocity (SAOV) information from the SAS and calculate a percent of outside airflow into the outside air inlet (CFMOA) value, an actual return airflow (CFMRA) value and a total supply air outflow (CFMSA) value responsive to,
% Outside Air=((TRA−TMA)/(TRA−TOA))*100;
CFMSA=(VAF*AF);
CFMOA=(% Outside Air)*(VAF*AF);
CFMRA=(VAF*AF)−CFMOA,
wherein if the Temperature Differential (TD) between the Outside Air (OA) and the Return Air (RA) is less than 10° F., the processing device is configured to determine the position of the at least one first damper slat and determine the percent of outside airflow into the outside air inlet (CFMOA) value, the actual return airflow (CFMRA) value and the total supply air outflow (CFMSA) value via a predetermined reference.
A method for measuring outside airflow and return airflow for an air handling system is provided, wherein the air handling system includes an outside air inlet, a mixed air chamber, a return air inlet, a supply air outlet and a supply fan having a Supply Airflow Station (SAS) with a fixed area, wherein the mixed air chamber is separated from the outside air inlet via a first damper having at least one configurable first damper slats, wherein the method is implemented via an Airflow Measuring System (AMS) having an Outside Air Temperature Sensor (OATS) located proximate the outside air inlet, a Return Air Temperature Sensor (RATS) located proximate the return air inlet, a Mixed Air Temperature Sensor (MATS) located within the mixed air chamber, a damper actuator, wherein the damper actuator is communicated with the first damper to configure the at least one first damper slat between an open configuration and a closed configuration, and a processing device, wherein the processing device is configured to receive temperature information from the OATS, the RATS and the MATS and Supply Air Output Velocity (SAOV) information from the SAS and damper position information and is communicated with the damper actuator to configure the at least one first damper slat between an open configuration and a closed configuration. The method includes determining if the Temperature Differential (TD) between Outside Air (OA) and Return Air (RA) is greater than or equal to 10° F. If the TD is less than 10° F., then determining a position of the at least one configurable first damper slat, and referencing a predetermined reference table to identify a percent of outside airflow into the outside air inlet (CFMOA) value, an actual return airflow (CFMRA) value and a total supply air outflow (CFMSA) value responsive to the position of the at least one configurable first damper slat. If the TD is greater than or equal to 10° F., then processing temperature information from the OATS, the RATS and the MATS and Supply Air Output Velocity (SAOV) information from the SAS to determine the percent of outside airflow into the outside air inlet (CFMOA) value, the actual return airflow (CFMRA) value and the total supply air outflow (CFMSA) value.
The foregoing and other features and advantages of the present invention should be more fully understood from the accompanying detailed description of illustrative embodiments taken in conjunction with the following Figures in which like elements are numbered alike in the several Figures:
Referring to the FIG.'s, a system and method for accurately measuring outside airflow for an HVAC system across a wide temperature range is provided and disclosed, in accordance with one embodiment of the invention.
Referring to the
It should be appreciated that the first damper 120 includes a first damper opening 128 and a plurality of first damper slats 130 disposed to cover the first damper opening 128, wherein the first damper slats 130 are configurable between an open configuration 132 and a closed configuration 134 (See
Referring again to
It should be further appreciated that the processing device 210 is configured to be in signal communication (hardwired and/or wirelessly) with the OATS 202, the RATS 204, the MATS 206, the SAS 118, the damper controller/actuator 208 and/or the inclinometer 212. Accordingly, the processing device 210 may receive temperature information from the OATS 202, the RATS 204 and the MATS 206, Supply Air Output Velocity (SAOV) (VAF) information from the SAS 118 and damper information (such as the position of the slats 124) from the inclinometer 212. It should be appreciated that the SAOV (VAF) may be determined via any method suitable to the desired end purpose, such as by locating a sensor at the fan outlet 126, the supply air outlet 114 (or farther down the line) and/or the SAOV (VAF) may be determined and provided by the supply fan 116. It is contemplated that in at least one embodiment, the processing device 210 may continuously (or periodically as desired) monitor the airflow of system 100 and automatically (or as desired) adjust the first damper 120 and/or the second damper 122 as desired. Additionally, it is contemplated that the processing device 210 may be communicated with the OATS 202, the RATS 204, the MATS 206, the SAS 118, and/or the inclinometers 212 of the first damper 120 and/or the second damper 122 to be able to monitor (in real time or periodically) the status of the OATS 202, the RATS 204, the MATS 206, the SAS 118, the first damper 120 and/or the second damper 122, as desired.
It should be appreciated that while in one embodiment of the invention, the first damper 120 and second damper 122 are described as having a plurality of slats, it is contemplated that in other embodiments the first damper 120 and/or second damper 122 may each have only one slat.
Referring to
Once the predetermined period of time T has expired, the inclinometer 212 measures the position of the damper slats 124 as a damper angle degree and/or as a percentage of the opened configuration 132 and/or the closed configuration 134, as desired. It should be appreciated that the ‘learning mode’ may be applied to the HVAC system 100 for any desired degree range of the position of the damper slats 124 suitable to the desired end purpose. For example, in one embodiment, the HVAC system 100 may be configured to calculate outside air (OA) % and/or return air (RA) % for each 1 degree of the position of the damper slats 124, while in another embodiment the HVAC system 100 may be configured to calculate OA % and/or RA % for each 5 degrees of the position of the damper slats 124. This method may also apply using damper positions as a percentage of the opened configuration 132 and/or the closed configuration 134 of the damper slats 124, if desired.
Once the predetermined period of time T has expired and the position of the damper slats 124 has been measured, the RAT, MAT, OAT and Supply Air in cubic feet per minute (CFMSA) are measured/determined. Once the RAT, MAT, OAT and Supply Air in cubic feet per minute (CFMSA) are measured/determined, the % OAF into the HVAC system 100 (CFMOA) and the actual return airflow (CFMRA) is calculated and the CFMOA, CFMRA and total CFMSA for the respective damper position is stored to generate a reference table (in Random Access Memory (RAM) or in a storage device), as shown in operational block 306. It should be appreciated that this step is repeated until the % OAF and actual return airflow for the HVAC system 100 is calculated for each of the positions of the damper slats 124 between a desired position range, such as for example 0° to 90° and/or 0% and 100%. These values may then be stored for future use. It should be appreciated that the % OAF (% Outside Air) in cubic feet minute (CFMOA) and actual return airflow (CFMRA) may be calculated using the following formulas:
% Outside Air=((TRA−TMA)/(TRA−TOA))*100;
CFMSA=(VAF*AF);
CFMOA=(% Outside Air)*(VAF*AF);
CFMRA=(VAF*AF)−CFMOA.
The method 300 further includes operating the Airflow Measuring System 200 to determine the position of the damper slats 124 and then identifying the CFMOA, CFMRA and total CFMSA for that particular position of the damper slat 124 from the stored values, as shown in operational block 308.
Accordingly, once the reference table is generated, the Airflow Measuring System 200 is operated to identify the temperature differential between the outside air (OA) and the Return Air (RA). If the temperature differential between the outside air (OA) and the Return Air (RA) is greater than or equal to 10° F., then the processing device is configured to process the temperature information from the OATS, the RATS and the MATS and Supply Air Output Velocity (SAOV) information from the SAS and calculate a percent of outside airflow into the outside air inlet (CFMOA) value, an actual return airflow (CFMRA) value and a total supply air outflow (CFMSA) value and other values as desired. However, if the temperature differential between the outside air (OA) and the Return Air (RA) is less than 10° F., then processing device is configured to determine the position of the at least one first damper slat and determine the percent of outside airflow into the outside air inlet (CFMOA) value, the actual return airflow (CFMRA) value and the total supply air outflow (CFMSA) value using the reference table by identifying the position of the slat(s) and identifying the stored values for the slat position in the reference table. Moreover, it should be appreciated that in one embodiment of the invention, the reference table can be used for a temperature differential between the outside air (OA) and the Return Air (RA) that is less than 10° F. While in other embodiments it is contemplated that the method of the invention can be used for any temperature differential between the outside air (OA) and the Return Air (RA) as desired, such as, for example, a temperature differential between the outside air (OA) and the Return Air (RA) of 20° F. Moreover, it is contemplated that the article and method of the invention may be used with an air handling system that only includes one damper.
It should be appreciated that the Airflow Measuring System 200 the method 300 for measuring the outside airflow (OAF) and the return airflow (RAF) into an air handling system across a wide temperature range may be used with any system that delivers and/or handles air, such as for example, an Air handling unit (AHU), a Rooftop Unit (RTU), a Fan coil unit (FCU), Unit ventilator (UV), a Cabinet Unit Heater (CUH) and/or any other mechanical equipment that may deliver or otherwise handle air.
It should be further appreciated that Airflow Measuring System 200 for measuring airflow for an HVAC system 100 across a wide temperature range may be automatically controlled via the processing device 210 as desired. Thus, it is contemplated that the processing device 210 may monitor the system 200 (i.e. the OATS 202, the RATS 204, the MATS 206, the SAOV), perform calibration as required and/or adjust the system 200 to environmental conditions. Moreover, it is contemplated that the Airflow Measuring System 200 may be accessed, monitored and/or controlled via an application that is present on a PDA or wireless computer by wirelessly accessing the processing device 210 and the system 200 via the PDA or wireless computer. Accordingly, it is contemplated that in at least one embodiment, the airflow measuring system 200 may be configured such that the methods and embodiments described hereinabove may also be practiced, in whole or in part, via any device suitable to the desired end purpose, such as a computer, iPod, MP3 Player, a PDA, a Pocket PC and/or a Cell phone with connection capability.
In accordance with the present invention, the method 300 for measuring airflow of an HVAC system 100 across a wide temperature range using the Airflow Measuring System 200 may be implemented, wholly or partially, by a controller operating in response to a machine-readable computer program. In order to perform the prescribed functions and desired processing, as well as the computations therefore (e.g. execution control algorithm(s), the control processes prescribed herein, and the like), the controller may include, but not be limited to, power drivers, current monitoring, temperature sensing/reading articles, a processor(s), computer(s), memory, storage, register(s), timing, interrupt(s), communication interface(s), and input/output signal interface(s), as well as combination comprising at least one of the foregoing. Additionally, the controller (software, firmware and/or any other means of control) may monitor proper operation of the system. In case a fault is detected it may switch to a redundant system/component (failure could be due to lightning strike or any other problem).
Moreover, the method 300 for measuring airflow for an HVAC system 100 across a wide temperature range may be embodied in the form of a computer or controller implemented processes. The method may also be embodied in the form of computer program code containing instructions embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, Solid State Drives (SSD) and/or any other computer-readable medium, wherein when the computer program code is loaded into and executed by a computer or controller, the computer or controller becomes an apparatus for practicing the invention. The invention can also be embodied in the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer or controller, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein when the computer program code is loaded into and executed by a computer or a controller, the computer or controller becomes an apparatus for practicing the invention. When implemented on a general-purpose microprocessor the computer program code segments may configure the microprocessor to create specific logic circuits.
It should be appreciated that while the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes, omissions and/or additions may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope thereof. Moreover, it is contemplated that elements of one embodiment may be combined with elements of other embodiments as desired. Therefore, it is intended that the invention not be limited to a particular embodiment disclosed herein as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments (individually and/or combined) falling within the scope of the appended claims and/or information. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.
This application is related to and claims benefit of priority of the filing dates of U.S. Provisional Patent Application Ser. No. 62/908,968, filed Oct. 1, 2019 and U.S. Provisional Patent Application Ser. No. 62/985,935, filed Mar. 6, 2020, the contents of both of which are incorporated herein by referenced in their entireties.
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