(en)The present invention provides an induction unit having a primary air inlet area, a return air inlet area, and an outlet area. A baffle separates the housing of the induction unit into first and second air flow paths. A source of primary air is attached in fluid communication with the air inlet area and a bank of nozzles is positioned within the first air flow path and in fluid communication with the air inlet area. A return air vent is positioned in fluid communication with the return air inlet area. Heat exchange tubes are positioned adjacent the return air vent and within the return inlet area of the housing, and at least one fan is mounted within the housing and in the second air flow path, wherein the fan will accelerate return air passing over the heat exchange tubes, through the second air flow path, and out of the air exit vent.

1.ApplicationNumber: US-201514805798-A
1.PublishNumber: US-2016025358-A1
2.Date Publish: 20160128
3.Inventor: CHANDRASHEKAR VIKAS D.
MILLER JAMES H.
SHULTES WILLIAM R.

4.Inventor Harmonized: CHANDRASHEKAR VIKAS D(US)
MILLER JAMES H(US)
SHULTES WILLIAM R(US)

5.Country: US
6.Claims:
(en)The present invention provides an induction unit having a primary air inlet area, a return air inlet area, and an outlet area. A baffle separates the housing of the induction unit into first and second air flow paths. A source of primary air is attached in fluid communication with the air inlet area and a bank of nozzles is positioned within the first air flow path and in fluid communication with the air inlet area. A return air vent is positioned in fluid communication with the return air inlet area. Heat exchange tubes are positioned adjacent the return air vent and within the return inlet area of the housing, and at least one fan is mounted within the housing and in the second air flow path, wherein the fan will accelerate return air passing over the heat exchange tubes, through the second air flow path, and out of the air exit vent.

7.Description:
(en)REFERENCE TO RELATED APPLICATION
The present application relates and claims priority to U.S. Provisional Patent Application No. 62/027,454, filed Jul. 22, 2014, the entirety of which is hereby incorporated by reference.


BACKGROUND
1. Field of Invention
The present invention relates to HVAC equipment, and more particularly to induction units used to condition and recirculate air within a room.
2. Background of Art
Utilizing energy consumption in today's smart buildings is of great concern to owners and operators. The cost of energy to deliver the proper temperature, humidity and ventilation air is increasing. Building owners have very few options available to save the costs of cooling and heating while requirements of indoor air quality (“IAQ”) and ventilation are being mandated to higher levels.
Although improvements in HVAC controls have allowed basic cooling and heating systems to run more effectively and more efficiently, electrical cost to run the cooling airflow and heating airflow typically comprise over 50% of the running costs in a HVAC system. For example: in a typical hotel room occupied 75% of the time a standard HVAC unit or system would cost around $35 per month per hotel room to run the fans, components and controls.
Induction units are used to supply conditioned air within a room. Typically, induction units include an inlet where conditioned air is introduced into the unit and where it will then pass through a series of nozzles to accelerate the conditioned air towards the outlet. In addition, a series of louvers are positioned adjacent the nozzles for purposes of sucking in air from the room. A series of heat exchange tubes are positioned adjacent the return louvers and the return air thus passes over the heat exchange tubes prior to being mixed with the conditioned air and exiting the induction unit through exit louvers. A typical induction unit operates at fairly low pressures and will increase the volume of air introduced into a room by about 3 times the rate at which the primary air is supplied.
3. Objects and Advantages
It is an object and advantage of the present invention to provide an induction unit that increases the flow rate of air introduced into a room.
It is another object and advantage of the present invention to provide an induction unit that operates in an energy efficient manner.
Other objects and advantages of the present invention will in part be obvious and in part appear hereinafter.
SUMMARY OF THE INVENTION
In accordance with the foregoing objects and advantages, the present invention provides an induction unit comprising a housing having a primary air inlet area, a return air inlet area, and an outlet area. A baffle separates the housing into first and second air flow paths, and an inlet to which a source of primary air may be attached is positioned in fluid communication with the air inlet area of the housing. A plurality of nozzles are positioned within the first air flow path of the housing and in fluid communication with the air inlet area, and a return air vent is positioned in fluid communication with the return air inlet area. An air exit vent is positioned in the outlet area of the housing and in fluid communication with the first and second air flow paths, and a plurality of heat exchange tubes are positioned adjacent the return air vent and within the return inlet area of the housing. At least one fan is mounted within the housing and in the second air flow path, wherein the fan will accelerate return air passing over the heat exchange tubes, through the second air flow path, and out of the air exit vent. In its preferred form, each of the at least one fan is powered by a low voltage power source in order to provide an energy efficient solution. With the fan(s) installed in the second air flow path, the volume of air processed by the induction unit and delivered into the room through the air exit vents is approximately 10 times the volume of air supplied by the primary air source.
The present invention allows for the use of low voltage 12 VDC fans and low voltage 12 VDC controls to work in unison with a Low voltage 12 VDC ventilation damper. This low voltage concept will allow the use of solar arrays to operate the unit's controls and components thus reducing the annual cost of operation. This offers more flexibility of operation to save energy. This invention also reduces the size of the backup generators required in an emergency. The unit's total input watts for operating the fans, and control valves and vent damper and on board Microprocessor controller is only 16 watts at 12 VDC.
In comparison to the example provided in the Background above, wherein a typical cost to run the HVAC system in a hotel room is about $74/month, the present invention would run for under $35 per month while delivering better airflow and better IAQ at much less operating cost for the owners. The present invention's utilization of 12 Vdc magnetic bearing fan technology has a sustainably of 150,000 hours of operation without failure. All the component parts of the invention are designed for low maintenance and long service life.



BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more fully understood and appreciated by reading the following Detailed Description in accordance with the drawing figures in which:
FIG. 1 is a perspective view of an embodiment of the present invention;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a first side elevation view thereof;
FIG. 7 is a second side elevation view thereof;
FIG. 8 is a longitudinally taken cross-sectional view taken along section line 8 - 8 of FIG. 2 ;
FIG. 9 is the perspective of the cross-sectional view of FIG. 8 ;
FIG. 10 is a flow rate diagram visualizing the air flow rates at various points within the induction unit when only the primary air source is providing air flow;
FIG. 11 is a flow rate diagram visualizing the air flow rates at various points within the induction unit when only the fan is providing air flow; and
FIG. 12 is a flow rate diagram visualizing the air flow rates at various points within the induction unit when the primary air source and the fan are providing air flow.



DETAILED DESCRIPTION
Referring now to the drawings, in which like reference numerals refer to like parts throughout, there is seen in FIG. 1 an induction unit, designated generally by reference numeral 10 . Induction unit 10 is adapted to be mounted in a wall between wall studs with the front face 12 of housing 14 exposed to the interior of the room and essentially lying co-planar with the wall in which it is installed. In use, induction unit 10 provides a room with a constant and uniform flow of conditioned air.
Induction unit 10 generally comprises a housing in which a primary air source inlet 16 is formed and to which a primary air source 18 is attached for purposes of delivering conditioned air into an air inlet area 20 formed within housing 14 of induction unit 10 . As the pressure produced by primary air source 18 pushes the conditioned air into air inlet area 20 , it passes through a bank of converging nozzles 22 which accelerate the air into a primary air flow path 24 formed within housing 14 . The conditioned air will continue to flow through air flow path 24 and eventually exit housing 14 through air exit vent 26 where it is dispersed into the room in which unit 10 is placed.
As air flows into the room, it will be induced back into unit 10 through the return air vent 28 due to the pressure differential created by the air flow within unit 10 and the air pressure in the room. As return air enters induction unit 10 through return air vent 28 it passes over a plurality of heat exchange tubes 30 that are used to heat and/or cool the return air. Once the return air passes over tubes 30 , the air takes one of two paths; either the return air joins the conditioned air coming from air source 18 or the air is pulled through a second air flow path 32 in which only return air moves. Return air flow path 32 and primary air flow path 24 are separated within housing 14 by a baffle 34 . The return air that flows through return air flow path 32 eventually exits unit 10 through air exit vent 26 where it does join the air that was pushed through the primary air flow path 24 .
To push a higher volume of air through unit 10 and into the room, the present invention further comprises a fan 36 (or a bank of fans that extend across the width of unit 10 ) positioned within return air flow path 32 . Fan 36 will partially serve to pull a higher volume of return air in though return air vent 28 , and then further serve to accelerate and increase the volume of return air being moved through return air flow path 32 and out of unit 10 through exit vent 26 . In its preferred form, fan 36 is a low voltage fan that operates on a 12V power supply (not shown). This same power supply also powers the unit's control logic, primary air damper and room thermostat. To facilitate ease of installation, fan(s) 36 can be mounted to a frame 37 that can be slid into and out of channels formed within housing 14 in order to position fan(s) 36 within return air flow path 32 .
The 12 v electrical controls for unit 10 are all contained within a control compartment 38 formed within housing 14 and sealed off from the air flow occurring within the housing. An access panel 40 may be removed to gain access to the controls for maintenance and repair. In addition, a drain pan 42 and drain 44 are provided for any condensate that forms on and drips from tubes 30 .
Induction unit 10 can be selectively operated in one of several modes via a control system; it can operate with only the primary air source 18 actuated (and fan 36 turned off), it can operate with primary air source 18 turned off and only fan 36 turned on, or it can operate with both primary air source 18 actuated and fan 36 turned on. Each of these three operating modes produces different air flow rates and hence volumes of air moved through the unit. With a series of 12V fans 36 mounted in an induction unit 10 , the table below shows the resulting air flow rates:












Static Pressure
Primary
Induced Air
Induction

Mode
in. W.C.
Air
(Air over Coil)
Ratio











Primary Air +
0.4
34
327
9.6

Fan Running

Fan Only
NA
0
264
NA

Primary Only
0.4
34
92
2.7
























As seen in the table, with the primary air source 18 and fan 36 both operating, a nearly 10:1 induction ratio is achieved. That is, ten times higher volume of air exits induction unit than provide into unit 10 by primary air source 18 . Without fan 26 operating, the induction ratio falls to about 3:1. Thus, fan 36 increases air flow rate by approximately three times as compared to an induction unit that relies solely on primary air source 18 to move the air.
With respect to FIGS. 10-12 , visualizations of the air flow velocities when only the primary air source 18 is providing air flow ( FIG. 10 ), when only the fan 36 is providing air flow ( FIG. 11 ), and when the primary air source 18 and the fan 36 are providing air flow ( FIG. 12 ) are provided. As the visualizations illustrate, the velocity flow rate of the air is greatest when both fan 36 and primary air source 18 are actuated.
Although the present invention has been described in connection with a preferred embodiment, it should be understood that modifications, alterations, and additions can be made to the invention without departing from the scope of the invention as defined by the claims.