Variable volume induction nozzle

Abstract

A variable volume induction nozzle is designed for use with a variable speed fan, where fan speed is adjusted in response to variable exhaust gas flow volume in order to conserve energy. In order to maintain a minimum exhaust discharge velocity to ensure adequate plume height, an axially-extendable, upwardly tapered flow-impinging pod within the nozzle creates a variable annular nozzle outlet opening. As opposed to a circumferentially-constricted outlet opening, the variable annular outlet produces a uniform discharge velocity profile conducive to the induction of ambient air through a windband.

Claims

1. A variable volume induction nozzle for vertical connection to a fan outlet for an exhaust gas from a variable speed fan, the nozzle comprising: a nozzle wall, defining a nozzle plenum, which has a central longitudinal axis constituting a plenum axis, wherein the nozzle wall comprises a lower wall section and an upper wall section, and and wherein the lower wall section terminates in a substantially circular nozzle exhaust inlet and the upper wall section terminates in a substantially circular nozzle discharge outlet, and wherein the nozzle exhaust inlet fluidly communicates with the fan outlet; an impinger pod, which is axially extendably disposed at an adjustable pod position within the nozzle plenum, wherein the impinger pod comprises a pod axis, consisting of a central longitudinal axis of the impinger pod, and wherein the pod axis is aligned, at each adjustable pod position, with the plenum axis, and wherein the impinger pod defines within the nozzle plenum, in conjunction with the nozzle wall, a variable annular effluent passageway for the exhaust gas, and wherein the impinger pod comprises an inwardly and upwardly conically tapered upper pod section, which terminates in a convex pod tip, in order to induce a laminar inflow of ambient air through a windband, and a lower pod section, and wherein the effluent passageway comprises an upper affluent passageway and a lower effluent passageway; wherein the impinger pod is vertically axially extendable, along the plenum axis, to a full pod extension, in which the pod tip maximally extends above the nozzle discharge outlet, and wherein the impinger pod is vertically axially retractable, along the plenum axis, to a full pod retraction, in which the pod tip does not extend above the nozzle discharge outlet or minimally extends above the nozzle discharge outlet, and wherein the impinger pod is vertically axially extendable and retractable to multiple intermediate pod positions, along the plenum axis, between the full pod extension and the full pod retraction; and wherein, when the impinger pod is at full pod retraction, the nozzle is in a fully open position, corresponding to a maximum flow of exhaust gas, with the fan operating at a maximum fan speed, and wherein, when the impinger pod is at full pod extension, the nozzle is in a fully closed position, corresponding to a minimum flow of exhaust gas, with the fan operating at a minimum fan speed, and wherein, when the impinger pod is at one of the intermediate pod positions, the nozzle is in an intermediate position, corresponding to an intermediate flow of exhaust gas, with the fan operating between the minimum fan speed and the maximum fan speed.

2. The nozzle of claim 1, wherein the nozzle wall has an upward wall taper, such that the nozzle wall tapers from the lower wall section to the upper wall section.

3. The nozzle of claim 2, wherein the lower wall section is tubular and the upper wall section is tapered frusto-conical.

4. The nozzle of claim 3, wherein the impinger pod has an upward pod taper, such that the impinger pod tapers from the lower pod section to the upper pod section.

5. The nozzle of claim 4, wherein the upward pod taper conforms to the upward wall taper.

6. The nozzle of claim 5, wherein the lower pod section is tubular, the upper pod section is substantially conical or frusto-conical, and the pod tip is rounded or hemispherical.

7. The nozzle of claim 6, wherein the upper effluent passageway has an annular convergence which is determined by the pod position, such that the annular convergence increases, and the upper effluent passageway narrows, as the impinger pod is adjusted from the full pod retraction to the full pod extension.

8. The nozzle of claim 7, wherein the pod position is adjustable by a linear actuator, which moves the lower pod section along a tubular guide sleeve between the full pod retraction and the full pod extension.

9. The nozzle of claim 8, further comprising one or more sensors and a central processing unit (CPU), wherein the CPU continuously or periodically activates the linear actuator to adjust the pod position, based upon one or more sensor readings.

10. The nozzle of claim 9, wherein the sensor readings comprise one or more of the following group: (i) flow velocity or velocity pressure of the exhaust gas at the nozzle discharge outlet, (ii) flow velocity or velocity pressure of the exhaust gas at the nozzle exhaust inlet, (iii) ambient cross-wind speed, and (iv) fan motor speed.

11. The nozzle of claim 5, wherein the upper effluent passageway has an annular convergence which is determined by the pod position, such that the annular convergence increases, and the upper effluent passageway narrows, as the impinger pod is adjusted from the full pod retraction to the full pod extension.

12. The nozzle of claim 11, wherein the pod position is adjustable by a linear actuator, which moves the lower pod section along a tubular guide sleeve between the full pod retraction and the full pod extension.

13. The nozzle of claim 12, further comprising one or more sensors and a central processing unit (CPU), wherein the CPU continuously or periodically activates the linear actuator to adjust the pod position, based upon one or more sensor readings.

14. The nozzle of claim 13, wherein the sensor readings comprise one or more of the following group: (i) flow velocity or velocity pressure of the exhaust gas at the nozzle discharge outlet, (ii) flow velocity or velocity pressure of the exhaust gas at the nozzle exhaust inlet, (iii) ambient cross-wind speed, and (iv) fan motor speed.

15. The nozzle according to any one of claims 1 through 10, further comprising a frusto-conical windband, which is attached in converging annular spaced relation to the nozzle wall, and which concentrically surrounds the nozzle discharge outlet, so as to define an upward-tapering frusto-conical windband exhaust passage, extending from a lower windband inlet opening to an upper windband outlet opening, such that a high velocity discharge of the exhaust gas from the nozzle discharge outlet induces an ambient air inflow upward through the windband exhaust passage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side profile exterior view of an exemplary variable volume induction nozzle in accordance with the preferred embodiment of the present invention;

(2) FIG. 2 is a longitudinal cross-section view of the exemplary variable volume induction nozzle of FIG. 1, taken along line A-A, showing the impinger pod in the fully open position;

(3) FIG. 3 is a longitudinal cross-section view of the exemplary variable volume induction nozzle of FIG. 1, taken along line A-A, showing the impinger pod in an intermediate position;

(4) FIG. 4 is a longitudinal cross-section view of the exemplary variable volume induction nozzle of FIG. 1, taken along line A-A, showing the impinger pod in the fully closed position;

(5) FIG. 5A is the longitudinal cross-section view of FIG. 2, corresponding to the fully open pod position, with cross-hatching designating four airflow regions;

(6) FIG. 5B is an axial cross-section view of the exemplary nozzle, taken along line B-B in FIG. 5A, with cross-hatching designating two airflow regions;

(7) FIG. 5C is an axial cross-section view of the exemplary nozzle, taken along line C-C in FIG. 5A, with cross-hatching designating two airflow regions;

(8) FIG. 5D is an axial cross-section view of the exemplary nozzle, taken along line D-D in FIG. 5A, with cross-hatching designating two airflow regions;

(9) FIG. 6A is the longitudinal cross-section view of FIG. 3, corresponding to the intermediate pod position, with cross-hatching designating four airflow regions;

(10) FIG. 6B is an axial cross-section view of the exemplary nozzle, taken along line B-B in FIG. 6A, with cross-hatching designating two airflow regions;

(11) FIG. 6C is an axial cross-section view of the exemplary nozzle, taken along line C-C in FIG. 6A, with cross-hatching designating two airflow regions;

(12) FIG. 6D is an axial cross-section view of the exemplary nozzle, taken along line D-D in FIG. 6A, with cross-hatching designating two airflow regions;

(13) FIG. 7A is the longitudinal cross-section view of FIG. 4, corresponding to the fully closed pod position, with cross-hatching designating four airflow regions;

(14) FIG. 7B is an axial cross-section view of the exemplary nozzle, taken along line B-B in FIG. 7A, with cross-hatching designating two airflow regions;

(15) FIG. 7C is an axial cross-section view of the exemplary nozzle, taken along line C-C in FIG. 7A, with cross-hatching designating two airflow regions;

(16) FIG. 7D is an axial cross-section view of the exemplary nozzle, taken along line D-D in FIG. 7A, with cross-hatching designating two airflow regions; and

(17) FIG. 8 is a schematic diagram depicting an exemplary control system for the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(18) Referring to FIG. 1, the preferred embodiment of the present invention comprises a variable volume induction nozzle, which is vertically connected to the primary exhaust gas outlet 1 of a variable speed fan by way of a flange at the nozzle exhaust inlet 2. The nozzle wall comprises a tubular lower section 3 and a tapered frusto-conical upper section 4. The nozzle further comprises a frusto-conical windband 5, which is attached to the upper section 4 of the nozzle wall by multiple mounting brackets 6.

(19) FIGS. 2-4 depict cross-section views of the variable volume induction nozzle. FIG. 2 depicts the nozzle in the fully open position, corresponding to a condition of maximum primary exhaust flow, with the fan operating at maximum speed. FIG. 4 depicts the nozzle in the fully closed position, corresponding to a condition of minimum primary effluent flow, with the fan operating at minimum speed. FIG. 3 depicts the nozzle in an intermediate position, with the fan operating between minimum and maximum speed.

(20) Referring to FIGS. 2-4, the fan outlet 1 defines an annular exhaust gas passageway 19 surrounding the fan motor housing 7. The annular fan outlet exhaust gas passageway 19 fluidly communicates through the nozzle inlet 2 with a uniform annular lower effluent passage 20 in the nozzle's lower section 3. This lower effluent passage 20 is defined by an axially-disposed tubular pod lower section 14. A conically tapered pod upper section 16the taper of which matches that of the upper section 4 of the nozzle walldefines a converging annular upper effluent passage 23.

(21) In the fully open position, as shown in FIG. 2, the rounded pod tip 22 is aligned with the nozzle's exhaust discharge outlet 28, such that the exhaust flow from the annular upper effluent passage 23 converges linearly at a first exhaust convergence point 21, downstream of the windband inlet opening 24, thereby inducing a laminar annular inflow of ambient air through the windband inlet opening 24. In the fully closed position, as shown in FIG. 4, the pod tip 22 projects through the nozzle's exhaust gas discharge outlet 28 and extends to a location below the windband outlet opening 25. In the closed position, the exhaust flow from the annular upper effluent passage 23 converges linearly at a second exhaust convergence point 26, downstream of the windband outlet opening 25, thereby inducing a laminar annular inflow of ambient air through the windband inlet opening 24.

(22) Referring to FIGS. 2-4, the motion of the impinger pod between the open position and the closed position is controlled by a linear actuator 10 acting through an actuator screw 12 on a screw travel nut 13 connected to the pod's upper section 16. The pod's tubular lower section 14 moves up and down, in response to the linear actuator 10, along a conforming tubular guide sleeve 9, with its travel alignment controlled by a guide key 18 within a conjugate guide track 17.

(23) Near the nozzle's discharge outlet 28, a velocity sensor-processor 27 is located, which takes periodic measurements of the discharge velocity of the exhaust gas, compares it with a velocity set point, and signals the linear actuator 10 to either lower the impinger pod to a more open position, if the measured discharge velocity is above the set point, or raise the pod to a more closed position, if the measured discharge velocity is below the set point.

(24) As illustrated in FIGS. 5A-D, 6A-D and 7A-D, the converging annular upper effluent passage 23 generates a uniform accelerated primary airflow region 47, which maximizes the induced airflow 48 through the windband inlet opening 24 and generates a combined laminar discharge airflow 49 through the windband outlet opening 25.

(25) FIG. 8 depicts exemplary control system for the variable volume induction nozzle 45 and associated fan assembly. The flow rate of the primary exhaust has 30 is monitored 31, along with the static pressure 32 of the exhaust gas upstream of the fan 44. Based on these readings, a master controller (CPU) 42 activates a bypass air actuator 36 to control the opening and closing of a bypass air damper 35, so that a greater volume of bypass air 37 is introduced when the primary exhaust flow rate 31 and/or static pressure 32 drop below designated design values.

(26) The primary exhaust gas 30, augmented as needed by the bypass air 37, enters the fan plenum 43 through the fan's isolation damper 33, controlled by a spring-return actuator 34. From the fan 44, the augmented exhaust gas 30 37 flows through the nozzle 45, where its flow rate is accelerated to a degree determined by the position of the impinger pod, as controlled by the linear actuator 10.

(27) The CPU 42 monitors flow velocity and/or velocity pressure 38 near the nozzle outlet 25 and uses such data to adjust fan speed through a variable frequency drive 39 (connected to an electric power source 40), as well as pod position through the linear actuator 10, to achieve a required plume rise based on a design discharge velocity 46. The CPU 42 calculates the design discharge velocity 46 using the Briggs Equation and the prevailing cross-wind velocity, as measured by an anemometer 41 at the building roofline.

(28) Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that many additions, modifications and substitutions are possible, without departing from the scope and spirit of the present invention.