WO2010122117A1 - Ventilation system involving ultrasonic flow measurement - Google Patents

Ventilation system involving ultrasonic flow measurement Download PDF

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Publication number
WO2010122117A1
WO2010122117A1 PCT/EP2010/055374 EP2010055374W WO2010122117A1 WO 2010122117 A1 WO2010122117 A1 WO 2010122117A1 EP 2010055374 W EP2010055374 W EP 2010055374W WO 2010122117 A1 WO2010122117 A1 WO 2010122117A1
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WO
WIPO (PCT)
Prior art keywords
duct
humidity
ventilation system
air
flow
Prior art date
Application number
PCT/EP2010/055374
Other languages
French (fr)
Inventor
Niels Lervad Andersen
Hans Schmidt-Hansen
Original Assignee
Syddansk Universitet
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Syddansk Universitet filed Critical Syddansk Universitet
Publication of WO2010122117A1 publication Critical patent/WO2010122117A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F7/00—Ventilation
    • F24F7/04—Ventilation with ducting systems, e.g. by double walls; with natural circulation
    • F24F7/06—Ventilation with ducting systems, e.g. by double walls; with natural circulation with forced air circulation, e.g. by fan positioning of a ventilator in or against a conduit
    • F24F7/065—Ventilation with ducting systems, e.g. by double walls; with natural circulation with forced air circulation, e.g. by fan positioning of a ventilator in or against a conduit fan combined with single duct; mounting arrangements of a fan in a duct
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/0001—Control or safety arrangements for ventilation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/70—Control systems characterised by their outputs; Constructional details thereof
    • F24F11/72—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure
    • F24F11/74—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/70—Control systems characterised by their outputs; Constructional details thereof
    • F24F11/72—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure
    • F24F11/74—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity
    • F24F11/77—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity by controlling the speed of ventilators
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/667—Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/667—Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
    • G01F1/668—Compensating or correcting for variations in velocity of sound
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/22—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using measurement of acoustic effects
    • G01K11/24—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using measurement of acoustic effects of the velocity of propagation of sound
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G01K13/02—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G01K13/02—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow
    • G01K13/024—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow of moving gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2110/00—Control inputs relating to air properties
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2110/00—Control inputs relating to air properties
    • F24F2110/10—Temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2110/00—Control inputs relating to air properties
    • F24F2110/20—Humidity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2110/00—Control inputs relating to air properties
    • F24F2110/30—Velocity

Definitions

  • Ventilation system involving ultrasonic flow measurement
  • the present invention relates to an ultrasound air flow detector used in conjunction with ducts carrying air flow for heat, ventilation or air conditioning.
  • the present invention relates to air treatment or conditioning systems which include an air ventilation component for delivery of exterior (e.g. fresh) air to an interior space (e.g. of a building).
  • the invention for example, relates to air treatment systems that may provide for heating, ventilating, and/or cooling within or associated with an enclosed space such as the interior space of a building, of a room, etc.
  • WO2007134621 A1 discloses a climatic system for rapidly reaching and maintaining a predetermined air humidity and/or a predetermined temperature.
  • the document teaches that it is possible by using a temperature-regulating device and fans to rapidly reach and maintain a pre-determined air humidity and/or a predetermined temperature in a climatic chamber.
  • WO2009018652A1 discloses an energy recovery ventilation system which allows for continuous fan speed control.
  • the energy recovery ventilation described is capable of fine motor speed control without the disadvantages of high noise, low efficiency and a fixed number of speeds.
  • a controller is used to optimize the ventilation and energy efficiency of the system through the use of several temperature sensors.
  • the energy recovery ventilation also provides a control process for self-optimization of the energy recovery ventilation, in case the supply and exhaust airflows are unequal. An unbalance may be detected by calculating the thermal efficiencies of the exhaust and supply airflows.
  • WO2007065476A1 WO2008025934A1 , and WO2008053193A1 illustrate how ultrasound can be used to measure air flow in various contexts.
  • These prior art documents teach that the mass flow of a gas can be calculated using ultrasound sensors, by obtaining ultrasound time of flight signals, measuring gas pressure in the flow, calculating the instantaneous volumetric flow and sound velocity for the gas and calculating the mass flow from a relationship between the actual volumetric flow, the actual sound velocity, the actual pressure and a constant.
  • Prior art ultrasound devices for measuring air flow velocity utilize signals from a plurality of sensors mounted in struts generally located in a single, cross sectional plane extending through the duct.
  • the prior art air velocity detector systems mathematically average the signals output from the plurality of sensors located at discrete positions in a defined cross- sectional plane normal to the axial centerline of the duct.
  • air velocity at any point in a given cross-sectional plane of a duct is significantly different from the velocity at another point on the plane.
  • air velocity is lower near the walls of the duct and is greater along the axial center line of the duct.
  • the air velocity at any particular point in a defined cross section of the duct dramatically changes if the duct is angulated upstream of the cross-section.
  • Prior art systems utilize point measurement and mathematically average sensor output signals. The resulting average is not a true average of air flow or velocity through the duct.
  • the prior art systems suffer from another defect which results from the disruption of the air flow due to the diagonally disposed struts
  • the present invention overcomes these and other defects in prior art devices by measuring the actual air flow velocity, temperature, and humidity in the flow outlet(s) a ventilation system without restricting the flow.
  • the present invention provides a ventilation system, wherein a fan draws air from an exterior of a building or similar closed construction for circulation into an interior of the building, and produces a supply airflow through a ventilator unit, which is able to cool and heat air.
  • the ventilator unit may be equipped with a humidifying/dehumidifying device.
  • a controller controls the supply airflow in response to an input received from an ultrasound device placed in the supply air duct, wherein the ultrasound device measures the air flow and temperature.
  • a humidity sensor such as a capacitor-based sensor, measures the humidity of the air, and communicates the measurement to the controller for humidity regulation of the air.
  • a CO2-sensor may further allow regulation of the CO2 level in the air of the interior of the building by increasing the flow of the supply air.
  • the interior of the building to be ventilated is provided with temperature and humidity sensors, which sensors communicates measured values to the controller to allow for regulation of these parameters.
  • the humidity of the interior of the building may be regulated by either providing a humidifying/dehumidifying device in the ventilation system or by simply regulating the rate of the supply air flow.
  • the interior of the building is also provided with one or more CO2 sensors.
  • one or more outlet ducts are provided in the walls of the building to allow passive or active exhaustion of excess air.
  • flow measuring devices e.g. ultrasound based
  • these ducts may be provided to ensure that the supply air flow equals the exhaust air flow; this may e.g. facilitate leak detection.
  • the system of the present invention is preferably equipped with a valve for restricting or even closing the supply air flow.
  • a valve for restricting or even closing the supply air flow.
  • Such a valve is preferably closing in case of fire and in case no persons are present in the room.
  • the ultrasound device is used in combination with an air duct carrying air conditioned air there through.
  • a pair of ultrasonic transceivers is mounted in a spaced apart relationship facing each other on opposing surfaces of the duct thereby permitting unrestricted air flow there through, wherein the transceivers emit and receive ultrasound waves in an angle of 70-90 degrees relative to the surface of the duct.
  • the cross section (longitudinally) of the duct may surprisingly be reduced to as low as 10 to 40 cm without compromising the accuracy of the time-of-flight measurement performed by the transceivers.
  • Electronic circuitry is connected to the transceivers which excites the transceivers, processes the received ultrasonic signal, and determines the phase difference and time- of-flight between the transmitted ultrasonic signal and the received ultrasonic signal. This signal is then used to calculate the velocity and temperature of the air.
  • an RC circuit in connection with the timer of the ultrasound device the humidity of the air can be measured by measuring the time for charge/discharge the capacitor to a certain voltage level.
  • the present invention specifically provides a ventilation system comprising:
  • a ventilator drawing air from an exterior of a building through a ventilation duct into an interior of the building, the ventilator provided with means for producing a humidity and temperature conditioned supply airflow through the ventilator,
  • an ultrasound sensor positioned in the duct upstream and/or downstream the ventilator without restricting the airflow, said ultrasound sensor measuring the volume flow and the temperature of the air in the duct;
  • the ultrasound sensor comprises a pair of ultrasonic transceivers mounted in a spaced apart relationship facing each other on opposing surfaces of the duct thereby permitting unrestricted air flow there through, wherein the transceivers emit and receive ultrasound waves in an angle of 60-90 degrees, preferably 65-89 degrees, more preferably 70-88 degrees, and most preferably 75-87 degrees, relative to the surface of the duct.
  • the inventors have surprisingly found that the longitudinal distance between the transceivers may be as low as 2 to 40 cm, preferably 4 to 39 cm for duct diameters ranging from 10cm to 2000 cm.
  • an electronic circuitry is coupled to the ultrasonic transceivers having:
  • the electronic circuitry is further extended with the means for measuring the humidity of the supply airflow, wherein the means constitutes a capacitor-based humidity measuring component.
  • temperature and humidity sensors are provided in the interior of the building, wherein these sensors communicate with the controller in order to feed-back regulate the temperature and humidity of the air.
  • the humidity measured by the means for measuring humidity in the supply airflow is used to estimate time-of-flight between the ultrasound transceivers thereby correcting the measured supply airflow.
  • the system of the present invention is self configuring or self calibrating. This is achieved by e.g. circular channels with known diameters (100 mm, 150 mm, 210 mm etc).
  • the flow measuring device here ultrasound transceivers
  • the TOF between two transceivers is measured.
  • the distance between the transceivers is determined, and this distance is then calibrated to the known diameter of the channel.
  • the ultrasound device determines the phase differential (time-of-flight) between the transmitted ultrasonic signals and the received ultrasonic signals. This phase differential is then used to calculate the velocity, temperature, and humidity by correcting the calculated sound velocity from time of flight by the measured humidity of the air.
  • additional temperature signals are obtained in order to determine the velocity of the air.
  • ultrasonic signals are first sent in one direction (from a first ultrasonic transceiver to a second ultrasonic transceiver) and then sent from the opposite end (from the second transceiver to the first transceiver).
  • the resultant phase differential representative signals detected during each uni-directional transmission are subtracted from the other.
  • the resultant signal is utilized to obtain the air velocity.
  • the system is calibrated when no air is flowing through the duct.
  • the "still air" phase difference signal and time-of-flight is utilized as a reference signal to compute air velocity during normal operations.
  • the present invention furthermore provides a method of detecting air velocity, humidity, and temperature in the duct. Accordingly, there is provided a method for controlling with improved accuracy the flow, temperature and humidity in a ventilation system in order to achieve a better climate and to reduce the operating costs associated with prior art ventilation systems.
  • the system according to the present invention measures the flow, temperature and humidity in the outlet air with ultrasound devices that do not restrict the flow in the ventilation system.
  • the present invention provides a ventilation system 11 of the present invention embodying a volume flow controller, said volume flow controller comprising: a duct 5 made from sheet metal, wherein ultrasonic transmitter and receiver 1 are mounted in a spaced apart relationship facing each other on opposing surfaces of the duct 5, without restricting the flow there through, said ultrasonic transmitter and receiver 1 used to determine volume flow through the duct 5; a valve 3 a valve motor 2 for restricting the flow; electronic circuitry (here control box 4) is connected to the transceivers which excites the transceivers, processes the received ultrasonic signal, and determines the flow through the duct (5); a controller for controlling the flow in response to the determined flow by opening or closing the valve 3.
  • a volume flow controller comprising: a duct 5 made from sheet metal, wherein ultrasonic transmitter and receiver 1 are mounted in a spaced apart relationship facing each other on opposing surfaces of the duct 5, without restricting the flow there through, said ultrasonic transmitter and receiver 1 used to determine volume flow through the duct 5;
  • FIG. 1 diagrammatically illustrates a heat, ventilation or air conditioning air duct which includes diagonally mounted ultrasound transceivers as well as a valve for closing the supply air flow. These transceivers detect air flow, temperature, and humidity based on change in capacitance, and Time of flight difference (Phase difference).
  • FIG. 2 diagrammatically illustrates one embodiment of the present invention which is disposed in a duct connected with a ventilation system.
  • FIG. 3 diagrammatically illustrates another embodiment of the present invention, wherein a CO2 sensor is positioned adjacent to the ventilation system.
  • the present invention relates to an air velocity, humidity, and temperature detector used in combination with a ventilation duct.
  • FIG. 1 diagrammatically shows a duct 5 made from sheet metal, wherein ultrasonic transmitter and receiver 1 are mounted in a spaced apart relationship facing each other on opposing surfaces of the duct, without restricting the flow there through; the ultrasonic path 7 is used to determine the time-of-flight of the ultrasonic signal.
  • a valve 3 and a valve motor 2 for restricting the flow is provided.
  • Electronic circuitry 4 is connected to the transceivers which excites the transceivers, processes the received ultrasonic signal, and determines the phase difference and time-of-flight between the transmitted ultrasonic signal and the received ultrasonic signal. This signal is then used to calculate the velocity and temperature of the air.
  • These parameters are controlled by the controller 4 that communicates with a the valve 2 to regulate the temperature and velocity of the airflow and controlling the fan speed and the temperature of the ventilation unit by communication through the control box on the valve.
  • FIG. 2 diagrammatically shows a complete ventilation system 11 according to the present invention.
  • the system includes a ventilator 12 in flow communication with a fan drawing air from an exterior of a building through a ventilation duct into an interior of the building.
  • the ventilator is equipped with means for cooling/heating the air 14.
  • a pair of ultrasonic transceivers 15, 16 is mounted in a spaced apart relationship facing each other on opposing surfaces of the duct, without restricting the flow there through.
  • Electronic circuitry 17 is connected to the transceivers which excites the transceivers, processes the received ultrasonic signal, and determines the phase difference and time-of -flight between the transmitted ultrasonic signal and the received ultrasonic signal. This signal is then used to calculate the velocity and temperature of the air.
  • RC circuit in connection with the timer of the ultrasound device the humidity of the air can be measured is also measured.
  • controller 18 that communicates with the fan to regulate the temperature, humidity, and velocity of the airflow exiting the duct and enter the interior of the building.
  • Temperature 19 and humidity 20 sensors are provided in the interior of the building, where these sensors communicate with the controller in order to feed-back regulate the temperature and humidity of the air.
  • FIG. 3 shows a special way of utilizing a CO2 sensor in the ventilation system.
  • the sensor is mounted on the end plate of the ventilation duct, adjacent to the ceiling 10 of the room.
  • the CO2 sensor 8 (and possibly other air monitoring devices) is integrated in the ventilation duct (i.e. channel providing the room with fresh air).
  • the air that is blown into the room has the ability to transport air 9 from the lower region of the room (where persons are present) towards the CO2 sensor

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Acoustics & Sound (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

There is provided a ventilation system, wherein a fan draws air from an exterior of a building or similar closed construction for circulation into an interior of the building, and produces a supply airflow through a ventilator unit, which is able to cool and heat air. Moreover, the ventilator unit may be equipped with a humidifying/dehumidifying device. A controller controls the position of a valve or indirectly the speed of the fan, thereby adjusting the supply airflow in response to an input received from an ultrasound device placed in the supply air duct, wherein the ultrasound device measures the air flow and temperature.

Description

Ventilation system involving ultrasonic flow measurement
FIELD OF THE INVENTION
The present invention relates to an ultrasound air flow detector used in conjunction with ducts carrying air flow for heat, ventilation or air conditioning. In particular the present invention relates to air treatment or conditioning systems which include an air ventilation component for delivery of exterior (e.g. fresh) air to an interior space (e.g. of a building). The invention, for example, relates to air treatment systems that may provide for heating, ventilating, and/or cooling within or associated with an enclosed space such as the interior space of a building, of a room, etc.
BACKGROUND OF THE INVENTION
WO2007134621 A1 discloses a climatic system for rapidly reaching and maintaining a predetermined air humidity and/or a predetermined temperature. The document teaches that it is possible by using a temperature-regulating device and fans to rapidly reach and maintain a pre-determined air humidity and/or a predetermined temperature in a climatic chamber.
WO2009018652A1 discloses an energy recovery ventilation system which allows for continuous fan speed control. The energy recovery ventilation described is capable of fine motor speed control without the disadvantages of high noise, low efficiency and a fixed number of speeds. A controller is used to optimize the ventilation and energy efficiency of the system through the use of several temperature sensors. The energy recovery ventilation also provides a control process for self-optimization of the energy recovery ventilation, in case the supply and exhaust airflows are unequal. An unbalance may be detected by calculating the thermal efficiencies of the exhaust and supply airflows.
WO2007065476A1 , WO2008025934A1 , and WO2008053193A1 illustrate how ultrasound can be used to measure air flow in various contexts. These prior art documents teach that the mass flow of a gas can be calculated using ultrasound sensors, by obtaining ultrasound time of flight signals, measuring gas pressure in the flow, calculating the instantaneous volumetric flow and sound velocity for the gas and calculating the mass flow from a relationship between the actual volumetric flow, the actual sound velocity, the actual pressure and a constant.
Prior art ultrasound devices for measuring air flow velocity utilize signals from a plurality of sensors mounted in struts generally located in a single, cross sectional plane extending through the duct. The prior art air velocity detector systems mathematically average the signals output from the plurality of sensors located at discrete positions in a defined cross- sectional plane normal to the axial centerline of the duct. However, air velocity at any point in a given cross-sectional plane of a duct is significantly different from the velocity at another point on the plane. Generally, air velocity is lower near the walls of the duct and is greater along the axial center line of the duct. Further, the air velocity at any particular point in a defined cross section of the duct dramatically changes if the duct is angulated upstream of the cross-section. Prior art systems utilize point measurement and mathematically average sensor output signals. The resulting average is not a true average of air flow or velocity through the duct. The prior art systems suffer from another defect which results from the disruption of the air flow due to the diagonally disposed struts.
Meanwhile, none of the prior art documents known to the applicants indicate that ultrasound measurements may be used to determine the humidity and the temperature of the air flow. Thus, the prior art does neither describe nor suggest that ultrasound devices placed in the flow outlets of a ventilation system can be used to reduce the energy consumption of a ventilation system as well as to generate an improved air environment.
The present invention overcomes these and other defects in prior art devices by measuring the actual air flow velocity, temperature, and humidity in the flow outlet(s) a ventilation system without restricting the flow.
It is an object of the present invention to provide a combined air flow, humidity and temperature detector for controlling these parameters in ventilation or air conditioning ducts with a view to obtain an improved air quality. SUMMARY OF THE INVENTION
The present invention provides a ventilation system, wherein a fan draws air from an exterior of a building or similar closed construction for circulation into an interior of the building, and produces a supply airflow through a ventilator unit, which is able to cool and heat air. Moreover, the ventilator unit may be equipped with a humidifying/dehumidifying device. A controller controls the supply airflow in response to an input received from an ultrasound device placed in the supply air duct, wherein the ultrasound device measures the air flow and temperature.
In one embodiment a humidity sensor, such as a capacitor-based sensor, measures the humidity of the air, and communicates the measurement to the controller for humidity regulation of the air.
In another preferred embodiment of the invention a CO2-sensor may further allow regulation of the CO2 level in the air of the interior of the building by increasing the flow of the supply air. In order to obtain proper functioning of the system the interior of the building to be ventilated is provided with temperature and humidity sensors, which sensors communicates measured values to the controller to allow for regulation of these parameters. The humidity of the interior of the building may be regulated by either providing a humidifying/dehumidifying device in the ventilation system or by simply regulating the rate of the supply air flow. In the embodiment, wherein the CO2 level is measured the interior of the building is also provided with one or more CO2 sensors. In order to avoid supra atmospheric pressure in the interior of the building one or more outlet ducts are provided in the walls of the building to allow passive or active exhaustion of excess air. In these ducts flow measuring devices (e.g. ultrasound based) may be provided to ensure that the supply air flow equals the exhaust air flow; this may e.g. facilitate leak detection.
Moreover, the system of the present invention is preferably equipped with a valve for restricting or even closing the supply air flow. Such a valve is preferably closing in case of fire and in case no persons are present in the room.
As mentioned above the ultrasound device is used in combination with an air duct carrying air conditioned air there through. A pair of ultrasonic transceivers is mounted in a spaced apart relationship facing each other on opposing surfaces of the duct thereby permitting unrestricted air flow there through, wherein the transceivers emit and receive ultrasound waves in an angle of 70-90 degrees relative to the surface of the duct. When using such angles the cross section (longitudinally) of the duct may surprisingly be reduced to as low as 10 to 40 cm without compromising the accuracy of the time-of-flight measurement performed by the transceivers.
Electronic circuitry is connected to the transceivers which excites the transceivers, processes the received ultrasonic signal, and determines the phase difference and time- of-flight between the transmitted ultrasonic signal and the received ultrasonic signal. This signal is then used to calculate the velocity and temperature of the air. By simply introducing an RC circuit in connection with the timer of the ultrasound device the humidity of the air can be measured by measuring the time for charge/discharge the capacitor to a certain voltage level. These parameters are controlled by the controller that communicates with the fan to regulate the temperature, humidity, and velocity of the airflow.
Accordingly, the present invention specifically provides a ventilation system comprising:
• a ventilator drawing air from an exterior of a building through a ventilation duct into an interior of the building, the ventilator provided with means for producing a humidity and temperature conditioned supply airflow through the ventilator,
• a controller controlling temperature, humidity, and velocity of the supply airflow in response to input received from:
• an ultrasound sensor positioned in the duct upstream and/or downstream the ventilator without restricting the airflow, said ultrasound sensor measuring the volume flow and the temperature of the air in the duct;
• means for measuring the humidity of the supply airflow positioned in the duct upstream the ventilator without restricting the airflow; and
• one or more temperature and humidity sensors provided in the interior of the building, wherein the ultrasound sensor comprises a pair of ultrasonic transceivers mounted in a spaced apart relationship facing each other on opposing surfaces of the duct thereby permitting unrestricted air flow there through, wherein the transceivers emit and receive ultrasound waves in an angle of 60-90 degrees, preferably 65-89 degrees, more preferably 70-88 degrees, and most preferably 75-87 degrees, relative to the surface of the duct. The inventors have surprisingly found that the longitudinal distance between the transceivers may be as low as 2 to 40 cm, preferably 4 to 39 cm for duct diameters ranging from 10cm to 2000 cm.
It is preferred that an electronic circuitry is coupled to the ultrasonic transceivers having:
• means for determining the phase difference and time-of-flight between a transmitted ultrasound signal and a received ultrasound signal;
• means for calculating the velocity of the air flow in said duct based upon said phase difference and time-of-flight; • means for determining and calculating the temperature of the airflow; and
• means for determining and calculating the humidity of the airflow.
Preferably the electronic circuitry is further extended with the means for measuring the humidity of the supply airflow, wherein the means constitutes a capacitor-based humidity measuring component.
In another preferred embodiment of the present invention temperature and humidity sensors are provided in the interior of the building, wherein these sensors communicate with the controller in order to feed-back regulate the temperature and humidity of the air.
In a particularly preferred embodiment of the present invention the humidity measured by the means for measuring humidity in the supply airflow is used to estimate time-of-flight between the ultrasound transceivers thereby correcting the measured supply airflow.
Preferably the system of the present invention is self configuring or self calibrating. This is achieved by e.g. circular channels with known diameters (100 mm, 150 mm, 210 mm etc). When the flow measuring device (here ultrasound transceivers) is provided with electrical energy the TOF between two transceivers is measured. Based on the TOF the distance between the transceivers is determined, and this distance is then calibrated to the known diameter of the channel.
Particularly, the ultrasound device determines the phase differential (time-of-flight) between the transmitted ultrasonic signals and the received ultrasonic signals. This phase differential is then used to calculate the velocity, temperature, and humidity by correcting the calculated sound velocity from time of flight by the measured humidity of the air. In one embodiment, additional temperature signals are obtained in order to determine the velocity of the air. In another embodiment, ultrasonic signals are first sent in one direction (from a first ultrasonic transceiver to a second ultrasonic transceiver) and then sent from the opposite end (from the second transceiver to the first transceiver). The resultant phase differential representative signals detected during each uni-directional transmission are subtracted from the other. The resultant signal is utilized to obtain the air velocity. In another embodiment, the system is calibrated when no air is flowing through the duct. The "still air" phase difference signal and time-of-flight is utilized as a reference signal to compute air velocity during normal operations.
The present invention furthermore provides a method of detecting air velocity, humidity, and temperature in the duct. Accordingly, there is provided a method for controlling with improved accuracy the flow, temperature and humidity in a ventilation system in order to achieve a better climate and to reduce the operating costs associated with prior art ventilation systems. In particular, the system according to the present invention measures the flow, temperature and humidity in the outlet air with ultrasound devices that do not restrict the flow in the ventilation system.
Additionally the present invention provides a ventilation system 11 of the present invention embodying a volume flow controller, said volume flow controller comprising: a duct 5 made from sheet metal, wherein ultrasonic transmitter and receiver 1 are mounted in a spaced apart relationship facing each other on opposing surfaces of the duct 5, without restricting the flow there through, said ultrasonic transmitter and receiver 1 used to determine volume flow through the duct 5; a valve 3 a valve motor 2 for restricting the flow; electronic circuitry (here control box 4) is connected to the transceivers which excites the transceivers, processes the received ultrasonic signal, and determines the flow through the duct (5); a controller for controlling the flow in response to the determined flow by opening or closing the valve 3. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 diagrammatically illustrates a heat, ventilation or air conditioning air duct which includes diagonally mounted ultrasound transceivers as well as a valve for closing the supply air flow. These transceivers detect air flow, temperature, and humidity based on change in capacitance, and Time of flight difference (Phase difference).
FIG. 2 diagrammatically illustrates one embodiment of the present invention which is disposed in a duct connected with a ventilation system.
FIG. 3 diagrammatically illustrates another embodiment of the present invention, wherein a CO2 sensor is positioned adjacent to the ventilation system.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an air velocity, humidity, and temperature detector used in combination with a ventilation duct.
FIG. 1 diagrammatically shows a duct 5 made from sheet metal, wherein ultrasonic transmitter and receiver 1 are mounted in a spaced apart relationship facing each other on opposing surfaces of the duct, without restricting the flow there through; the ultrasonic path 7 is used to determine the time-of-flight of the ultrasonic signal. A valve 3 and a valve motor 2 for restricting the flow is provided. Electronic circuitry 4 is connected to the transceivers which excites the transceivers, processes the received ultrasonic signal, and determines the phase difference and time-of-flight between the transmitted ultrasonic signal and the received ultrasonic signal. This signal is then used to calculate the velocity and temperature of the air. These parameters are controlled by the controller 4 that communicates with a the valve 2 to regulate the temperature and velocity of the airflow and controlling the fan speed and the temperature of the ventilation unit by communication through the control box on the valve.
FIG. 2 diagrammatically shows a complete ventilation system 11 according to the present invention. The system includes a ventilator 12 in flow communication with a fan drawing air from an exterior of a building through a ventilation duct into an interior of the building. The ventilator is equipped with means for cooling/heating the air 14. A pair of ultrasonic transceivers 15, 16 is mounted in a spaced apart relationship facing each other on opposing surfaces of the duct, without restricting the flow there through. Electronic circuitry 17 is connected to the transceivers which excites the transceivers, processes the received ultrasonic signal, and determines the phase difference and time-of -flight between the transmitted ultrasonic signal and the received ultrasonic signal. This signal is then used to calculate the velocity and temperature of the air. By virtue of an RC circuit in connection with the timer of the ultrasound device the humidity of the air can be measured is also measured. These parameters are controlled by the controller 18 that communicates with the fan to regulate the temperature, humidity, and velocity of the airflow exiting the duct and enter the interior of the building. Temperature 19 and humidity 20 sensors are provided in the interior of the building, where these sensors communicate with the controller in order to feed-back regulate the temperature and humidity of the air.
FIG. 3 shows a special way of utilizing a CO2 sensor in the ventilation system. Basically the sensor is mounted on the end plate of the ventilation duct, adjacent to the ceiling 10 of the room. The CO2 sensor 8 (and possibly other air monitoring devices) is integrated in the ventilation duct (i.e. channel providing the room with fresh air). The air that is blown into the room has the ability to transport air 9 from the lower region of the room (where persons are present) towards the CO2 sensor

Claims

1. A ventilation system 11 comprising:
• a ventilator 12 drawing air from an exterior of a building through a ventilation duct into an interior of the building, the ventilator provided with means for producing a humidity and temperature conditioned supply airflow through the ventilator 12,
• a controller 18 controlling temperature, humidity, and velocity of the supply airflow in response to input received from:
• an ultrasound sensor positioned in the duct 5 upstream and/or downstream the ventilator without restricting the airflow, said ultrasound sensor measuring the volume flow and the temperature of the air in the duct 5;
• means for measuring the humidity of the supply airflow positioned in the duct 5 upstream the ventilator without restricting the airflow; and
• one or more temperature 19 and humidity sensors 20 provided in the interior of the building, wherein the ultrasound sensor comprises a pair of ultrasonic transceivers 15, 16 mounted in a spaced apart relationship facing each other on opposing surfaces of the duct 5 thereby permitting unrestricted air flow there through, wherein the transceivers 15, 16 emit and receive ultrasound waves in an angle of 60-90 degrees relative to the surface of the duct.
2. Ventilation system 11 according to claim 1 further comprising one or more CO2 sensors provided in the interior of the building and a controller for controlling the CO2 concentration of the supply airflow in response to input received from the one or more CO2 sensors.
3. Ventilation system 11 according to claim 1 , wherein an electronic circuitry is coupled to the ultrasonic transceivers having:
• means for determining the phase difference and time-of-flight between a transmitted ultrasound signal and a received ultrasound signal; • means for calculating the velocity of the air flow in said duct based upon said phase difference and time-of-flight; and
• means for determining and calculating the temperature of the airflow.
4. Ventilation system 11 according to claim 3, wherein the electronic circuitry is further extended the means for measuring the humidity of the supply airflow, wherein the means constitutes a capacitor-based humidity measuring component.
5. Ventilation system 11 according to any one of the preceding claims, wherein temperature and humidity sensors are provided in the interior of the building, wherein these sensors communicate with the controller in order to feed-back regulate the temperature and humidity of the air.
7. Ventilation system 11 according to any one of the preceding claims, wherein the humidity measured by the means for measuring humidity in the supply airflow is used to estimate time-of-flight between the ultrasound transceivers 15, 16, thereby correcting the measured supply airflow.
8. Ventilation system 11 according to any one of the preceding claims, wherein the system
11 is self configuring or self calibrating.
9. Ventilation system 11 according to any one of the preceding claims, wherein dirt depositing in the duct is coped with by the ultrasound transceivers 15, 16 by increasing the strength of the ultrasound.
10. Ventilation system 11 according to any one of the preceding claims, wherein at a CO2 sensor is placed at the end of the duct entering the interior of the building to be ventilated.
1 1. Ventilation system 11 according to any one of the preceding claims embodying a volume flow controller, said volume flow controller comprising: a duct 5 made from sheet metal, wherein ultrasonic transmitter and receiver 1 are mounted in a spaced apart relationship facing each other on opposing surfaces of the duct
5, without restricting the flow there through, said ultrasonic transmitter and receiver 1 used to determine volume flow through the duct 5; a valve 3 a valve motor 2 for restricting the flow; electronic circuitry connected to the transceivers which excites the transceivers, processes the received ultrasonic signal, and determines the flow through the duct (5); a controller for controlling the flow in response to the determined flow by opening or closing the valve 3.
PCT/EP2010/055374 2009-04-22 2010-04-22 Ventilation system involving ultrasonic flow measurement WO2010122117A1 (en)

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US17147109P 2009-04-22 2009-04-22
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EP09158447.4 2009-04-22
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WO2019087075A1 (en) * 2017-10-30 2019-05-09 Zehnder Group International Ag Air flow sensor and measuring method therefor
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KR20210072702A (en) * 2019-12-09 2021-06-17 (주)한국송풍기엔지니어링 An apparatus for measuring rate of discharge
KR102532289B1 (en) * 2019-12-09 2023-05-12 (주)한국송풍기엔지니어링 An apparatus for measuring rate of discharge
WO2021130309A1 (en) 2019-12-23 2021-07-01 Belimo Holding Ag System and method for improved measurement of a flow of fluid through a channel
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