METHOD AND APPARATUS FOR CONTROLLING VENTILATION SYSTEMS

• US 20100286831A1
• Filed: 07/31/2008
• Published: 11/11/2010
• Est. Priority Date: 08/03/2007
• Status: Active Grant

• Current Assignee: Air Tech Equipment, Ltd.
• Original Assignee: Air Tech Equipment, Ltd.
• Inventors: Boulay, Michael, Boudreau, Patrick Paul
• Granted Patent: US 8,939,827 B2
• Time in Patent Office: Days
• US Class Current: 700/278
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: F24F 12/006 using an air-to-air heat exchanger F24F12/002 takes precedence
• CPC Class Codes: Y02B 30/00 Energy efficient heating, ventilation or air conditioning [HVAC]
• CPC Class Codes: Y02B 30/56 Heat recovery units
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

An energy recovery ventilation system is described which allows for continuous fan speed control through pulse width modulation of direct current fans. 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 present in commonly-used speed-varying techniques used with alternating current (AC) fans. This may be accomplished through the use of direct current (DC) fans and pulse width modulation. 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.

Claims

1. A ventilation system comprising:

a ventilator;

a first direct current (DC) fan drawing air from an exterior of a building for circulation into an interior of the building, the first DC fan producing a supply airflow through the ventilator;

a second DC fan drawing a return air from the interior of the building for exhausting to the exterior of the building, the second DC fan producing an exhaust airflow through the ventilator enclosure, said supply airflow and said exhaust airflow undergoing an energy exchange therebetween in the ventilator; and

a controller controlling of a first speed of the first DC fan and a second speed of the second DC fan, thereby separately adjusting the supply airflow and the exhaust airflow in response to a first input received from a first temperature sensor in the supply airflow positioned upstream of the energy exchange in the ventilator, a second input received from a second temperature sensor in the supply airflow positioned downstream of the energy exchange in the ventilator and a third temperature sensor in an exhaust airflow positioned downstream of the energy exchange in the ventilator, said first, second and third temperature sensors each independently outputting temperature signals to the controller for use in optimizing the supply and exhaust airflows.

2. The ventilation system according to claim 1, further comprising a first humidity sensor in the supply airflow positioned upstream of the energy exchange in the ventilator and a second humidity sensor in the supply airflow positioned downstream of the energy exchange in the ventilator, said first and second humidity sensors each independently outputting humidity signals to the controller for use in optimizing the supply airflow and the exhaust airflow.

3. The ventilation system according to claim 1 wherein optimizing the supply airflow and the exhaust airflow comprises balancing the supply airflow and the exhaust airflow.

4. The ventilation system of claim 1, wherein the ventilator comprises at least one energy exchange core.

8. The ventilation system of claim 1, wherein the supply airflow and the exhaust airflow are separate in the ventilator but wherein heat and/or moisture exchange occurs between the supply and exhaust airflows.

9. The ventilation system according to claim 1, further comprising a recirculation fan for drawing a portion of the return air from the interior the building for recirculation in the interior of the building.

12. The ventilation system according to claim 1, further comprising a fourth temperature sensor positioned in the exhaust airflow at a position proximate to the exhaust inlet of the ventilator, the fourth temperature sensor outputting a signal to the controller for use in optimizing the supply airflow and the exhaust airflow.

14. The ventilation system according to claim 1, wherein the controller includes means for calculating a thermal efficiency for each of the supply airflow and the exhaust airflow for use in balancing the supply and exhaust airflows.

16. The ventilation system according to claim 1, having continuous fan speed control.

17. The ventilation system according to claim 1, wherein means for fine control of the fan speed of each of the first and the second DC fan comprises pulse width modulation (PWM).

5-7. -7. (canceled)

10-11. -11. (canceled)

13. (canceled)

15. (canceled)

18. A ventilator comprising:

a ventilator enclosure comprising a supply inlet receiving a supply airflow from an exterior of a building, a supply outlet discharging the supply airflow to the interior of the building, an exhaust inlet receiving an exhaust airflow from an interior of the building, and an exhaust outlet discharging the exhaust airflow to the exterior of the building,

a first direct current (DC) fan drawing supply air through the supply inlet and discharging supply air through the supply outlet, said first DC fan producing a supply airflow through the ventilator enclosure;

a second DC fan drawing return air through the exhaust inlet and discharging the exhaust air from the exterior of the building thereby creating the exhaust airflow through the ventilator enclosure;

a first temperature sensor, proximate to the supply inlet, determining a first temperature of supply air entering the ventilator enclosure;

a second temperature sensor, proximate to the supply outlet, measuring a second temperature of supply air exiting the ventilator enclosure;

a third temperature sensor, proximate to the exhaust outlet, measuring a third temperature of return air exiting the ventilator enclosure; and

a controller controlling the fans and regulating the supply airflow and the exhaust airflow, said controller comprising receiver receiving a first input from the first temperature sensor, a second input from the second temperature sensor, and a third input from a third temperature sensor, and drivers for independently adjusting a first fan speed for the first DC fan and a second fan speed for the second DC fan in response to each of said first, second and third inputs, thereby optimizing the supply airflow and the exhaust airflow.

19-25. -25. (canceled)

26. A method for optimizing ventilation efficiency of a ventilation system having a first direct current (DC) fan producing a supply airflow through a ventilator to an interior of a building, a second DC fan for producing an exhaust air flow of return air through a ventilator for exhausting to an exterior of the building, a first temperature sensor determining a temperature of the supply airflow upstream of the ventilator, a second temperature sensor determining a temperature of the supply airflow downstream of the ventilator, a third temperature sensor determining a temperature of the exhaust airflow downstream of the ventilator and a controller for independently adjusting the fan speed for each of the first and second DC fans in response to input received from the first, second and third temperature sensors, said method comprising the steps of:

determining a thermal efficiency for the supply airflow and the exhaust airflow from temperature data for the supply airflow and the exhaust airflow obtained from each of the first, second and third temperature sensors,

comparing the thermal efficiency for each of the supply airflow and the exhaust airflow with predetermined values,

determining whether the thermal efficiencies for supply and exhaust airflows are substantially equal to predetermined values, and

adjusting the fan speed of the first and/or the second fan where the thermal efficiencies of the supply airflow and/or the exhaust airflow are determined to be unequal.

27. A method for self-balancing a supply airflow and an exhaust airflow in a ventilation system, the ventilation system comprising a direct current (DC) supply fan for producing a supply airflow through a ventilator for circulation inside a building, a DC exhaust fan for producing an exhaust air flow of return air through a ventilator for exhausting outside of the building, a first temperature sensor for determining a temperature of the supply airflow at a supply inlet of the ventilator, a second temperature sensor for determining a temperature of the supply airflow at a supply outlet of the ventilator, a third temperature sensor for determining a temperature of the exhaust airflow at an exhaust outlet of the ventilator and a controller for independently adjusting the fan speed for each of the first and second DC fans in response to input received from the first, second and third temperature sensors, the method comprising:

at a preselected time, automatically determining a first thermal efficiency for the supply airflow using the supply inlet temperature and a second thermal efficiency for the exhaust airflow using the supply outlet temperature; and

adjusting the fan speed of the supply fan and/or the exhaust fan so as to substantially equalize the first thermal efficiency and the second thermal efficiency for the exhaust airflow.

28. The method of claim 27, further comprising the step of increasing the supply fan speed or decreasing the exhaust fan speed where the thermal efficiency for the supply airflow is greater than the thermal efficiency for the exhaust fan.

29. The method of claim 27, further comprising the step of decreasing the supply fan speed or increasing the exhaust fan speed where the thermal efficiency for the supply airflow is less than the thermal efficiency for the exhaust fan.

30. (canceled)

31. A method for controlling a ventilation system comprising:

measuring a temperature property of incoming supply air;

measuring a temperature property of treated supply air;

measuring a temperature property of exhaust air;

determining a flow rate of supply air and a flow rate of exhaust air for maximizing the effectiveness of the ventilation system based upon said measured temperature properties; and

adjusting duty cycles of PCM signals to each of a supply fan and an exhaust fan to substantially achieve said flow rates.

32. The method according to claim 31, further comprising the steps of measuring a humidity property of the incoming supply air and the treated supply air;

and determining the flow rate of supply air and the flow rate of exhaust air based upon the humidity properties.

33. A storage medium readable by a computer encoding a computer program for execution by the computer to carry out a method for optimizing ventilation efficiency of a ventilation system having a first direct current (DC) fan producing a supply airflow through a ventilator to an interior of a building, a second DC fan for producing an exhaust air flow of return air through a ventilator for exhausting to an exterior of the building, a first temperature sensor determining a temperature of the supply airflow upstream of the ventilator, a second temperature sensor determining a temperature of the supply airflow downstream of the ventilator, a third temperature sensor determining a temperature of the exhaust airflow downstream of the ventilator and a controller for independently adjusting the fan speed for each of the first and second DC fans in response to input received from the first, second and third temperature sensors, the computer program comprising:

code means for determining a thermal efficiency for the supply airflow and the exhaust airflow from temperature data for the supply airflow and the exhaust airflow obtained from each of the first, second and third temperature sensors,

code means for comparing the thermal efficiency for each of the supply airflow and the exhaust airflow with predetermined values,

code means for determining whether the thermal efficiencies for supply and exhaust airflows are substantially equal to predetermined values, and

code means for adjusting the fan speed of the first and/or the second fan where the thermal efficiencies of the supply airflow and/or the exhaust airflow are determined to be unequal.

34. A storage medium readable by a computer encoding a computer program for execution by the computer to carry out a method for self-balancing a supply airflow and an exhaust airflow in a ventilation system, the ventilation system comprising a direct current (DC) supply fan for producing a supply airflow through a ventilator for circulation inside a building, a DC exhaust fan for producing an exhaust air flow of return air through a ventilator for exhausting outside of the building, a first temperature sensor for determining a temperature of the supply airflow at a supply inlet of the ventilator, a second temperature sensor for determining a temperature of the supply airflow at a supply outlet of the ventilator, a third temperature sensor for determining a temperature of the exhaust airflow at an exhaust outlet of the ventilator and a controller for independently adjusting the fan speed for each of the first and second DC fans in response to input received from the first, second and third temperature sensors, the computer program comprising:

code means for determining a first thermal efficiency for the supply airflow using the supply inlet temperature and a second thermal efficiency for the exhaust airflow using the supply outlet temperature; and

code means for adjusting the fan speed of the supply fan and/or the exhaust fan so as to substantially equalize the first thermal efficiency and the second thermal efficiency for the exhaust airflow.