Device and method for controlling a supply air flow at an air treatment system

Abstract

Method and air treatment device (1) for control of supply air flow (L1). The air treatment device (1) comprises a chilled beam (2) with a pressure box (5) comprising an inlet (6) for inflow of supply air flow (L1) and a plurality of outlets (7) for outflow of the supply air flow (L1) out of the pressure box (5). The air treatment device (1) comprises an actuator (12) for control of supply air flow (L1), and the pressure box (5) comprises at least one pressure measuring socket (13) for control of static pressure (ps). The air treatment device (1) registers the static pressure (ps) and the position of the actuator (12), and calculates the real supply air flow (L1). The actuator (12) is arranged to change the configuration of the outlets (7) by a linear motion of a cover member (9) and change the open area of the outlets (7).

Claims

1. An air treatment device (1) for control of a supply air flow (L1) to a premises (A) and for conditioning of the supply air flow, the air treatment device (1) comprising: a chilled beam (2) being connected to a supply air duct (3) in an air treatment system (4), the chilled beam (2) comprising a pressure box (5) with at least one inlet (6) for inflow of the supply air flow (L1) from the supply air duct (3) to the pressure box (5), and a plurality of outlets (7) for outflow of the supply air flow (L1) out of the pressure box (5) to a mixing chamber (8), the plurality of outlets (7) being arranged according to a configuration which is changeable by that at least one cover member (9) displaceably arranged in relation to the plurality of outlets (7), the chilled beam (2) comprising at least one liquidly coupled heat exchanger (10) arranged to alternatively cool or heat a through-flowing air stream by heat exchange, through which heat exchanger (10) a circulation air flow (L2) from the premises is arranged to flow (A) due to induction effect driven by the passage of supply air flow (L1) out of the plurality of outlets (7) to the mixing chamber (8), the mixing chamber (8) being arranged to unite the supply air flow (L1) and, via the heat exchanger (10), the conditioned circulation air flow (L2) into a common air stream (L1+L2) and guide the common air stream (L1+L2) to at least one outlet opening (11) for outflow to the premises (A), the air treatment device (1) further comprising at least one actuator (12) for control of a volume flow of the supply air flow (L1), the pressure box (5) comprising at least one pressure measuring socket (13), useful for representative control of static pressure (ps) in the pressure box (5), and the air treatment system (4) comprising at least one room sensor (14), which is arranged to register room conditions in the premises (A) and communicate the room conditions to the air treatment system (4) for control of the air treatment device (1), wherein the air treatment device (1) is arranged to register the static pressure (ps) in the pressure box (5) and a position of the actuator (12) and, based on the static pressure (ps) and the position of the actuator (12), calculate a real supply airflow (L1) in the chilled beam (2), and the actuator (12) is arranged, at an identified need, to change a configuration of the plurality of outlets (7) by a linear motion of the cover member (9) so as to change an open area of the plurality of outlets (7) and change the supply air flow (L1) by displacement of the cover member (9).

2. The air treatment device according to claim 1, wherein the actuator (12) is arranged to register the static pressure (ps) in the pressure box (5) and the position of the actuator (12), and further, based on these, arranged to calculate the real supply airflow (L1) in the chilled beam (2) by software (15) in the actuator (12).

3. The air treatment device according to claim 1, wherein a pressure sensor (16) is arranged to register the static pressure (ps) in the pressure box (5), and the actuator (12) is arranged to, based on that and the position of the actuator (12), calculate the real supply airflow (L1) in the chilled beam (2) by software (15) in the actuator (12).

4. The air treatment device according to claim 1, wherein the air treatment system (4) comprises software (15) for registration of the static pressure (ps) in the pressure box (5) and a position of the actuator (12), and which software (15) is, based on these, arranged to calculate the real supply airflow (L1) in the chilled beam (2).

5. A method for control of supply air flow (L1) to a premises (A) and for conditioning of the supply air flow (L1) by means of an air treatment device (1) which comprises a chilled beam (2) connected to a supply air duct (3) in an air treatment system (4), the chilled beam (2) comprises a pressure box (5) with at least one inlet (6) for inflow of supply air flow (L1) from the supply air duct (3) to the pressure box (5) and a plurality of outlets (7) for outflow of the supply air flow (L1) out of the pressure box (5) to a mixing chamber (8), the plurality of outlets (7) are arranged according to a configuration which is changeable by that at least one cover member (9) which is displaceably arranged relative to the plurality of outlets (7), the chilled beam (2) comprises at least one liquidly coupled heat exchanger (10) arranged to alternatively cool or heat a through-flowing air stream by heat exchange, a circulation air flow (L2) from the premises (A) is arranged to flow due through the heat exchanger (10) to induction effect driven by the passage of supply air flow (L1) out of the plurality of outlets (7) to the mixing chamber (8), the mixing chamber (8) is arranged to unite, via the heat exchanger (10), the supply air flow (L1) and the conditioned, circulation air flow (L2) into a common air stream (L1+L2) and guide the common air stream (L1+L2) to at least one outlet opening (11) for outflow to the premises (A), the air treatment device (1) comprises at least one actuator (12) for control of a volume flow of the supply air flow (L1), and the pressure box (5) comprises at least one pressure measuring socket (13), useful for representative control of static pressure (ps) in the pressure box (5), and the air treatment system (4) comprises at least one room sensor (14), which is arranged to register the room conditions in the premises (A) and communicate the room conditions to the air treatment system (4) for control of the air treatment device (1), the method comprising: measuring the static pressure (ps) in the pressure box (5), registering the position of the actuator (12) for determining an actual configuration of the plurality of outlets (7) which gives an actual k-factor, calculating the real supply air flow (L1) for the chilled beam (2) based on the static pressure (ps) in the pressure box (5) and the position of the actuator (12), measuring/registering an actual status of the room conditions in the premises (A) by the room sensor (14), comparing the real supply air flow (L1) with a set point for the actual room condition, at a detected need change to a configuration of the plurality of outlets (7), moving the cover member (9) in relation to the plurality of outlets (7) by linear motion of the cover member (9) via the actuator (12), to change the supply air flow (L1) by which motion an open area of the plurality of outlets (7) changes for outflow of supply air flow (L1).

Description

SHORT DESCRIPTION OF THE FIGURES

(1) The following schematic principle figures show:

(2) FIG. 1 shows a simplified schematic drawing of an air handling system comprising an air handling unit, supply and exhaust air ducts and the air treatment device connected to the supply air duct and which air treatment device provides a premises with supply air.

(3) FIG. 2a shows a side view of the air treatment device.

(4) FIG. 2b shows a schematic drawing of a section through the air treatment device and the flow of air therethrough.

(5) FIG. 3 shows a view obliquely from below of a preferred embodiment of the device.

(6) The structural design of the present invention are apparent in the following detailed description of an embodiment of the invention with reference to the accompanying figures which show a preferred but not limiting embodiment of the invention.

DETAILED DESCRIPTION OF THE FIGURES

(7) FIG. 1 shows a simplified schematic drawing of an air treatment system 4 comprising an air handling unit 21 of conventional type for a VAV-system. The air handling unit 21 is connected to a supply air duct 3 and an exhaust air duct 20 and symbolically is shown that there normally are a number of branch ducts 24 connected to the system. Further, an air treatment device 1 is connected to one end of the supply air duct 3 and the air treatment device 1 provides a premises A with supply air, which is symbolically shown in the figure. In the premises A is a room sensor 14 and a presence sensor 17 provided for the registration of the current condition of the room, for presence or non-presence, room temperature and/or carbon dioxide level. Depending on how the system is intended to be controlled, the room sensor 14 may be in the form of a temperature sensor 18 and/or a carbon dioxide sensor 19. In the figure and subsequent figure descriptions relating to the invention are examples of when the air treatment system 4 comprises presence sensor 17, temperature sensor 18 and carbon dioxide sensor 19, why control of the plant can be based on presence, temperature and carbon dioxide.

(8) FIGS. 2a and 2b shows a side view through the air treatment device 1, and a section of the same. The air treatment device 1 comprises a chilled beam 2 and a linear actuator 12, which is arranged on the chilled beam 2. The chilled beam 2 is connected to the supply air duct 3 and supply air arrives to the chilled beam pressure box 5 through an inlet 6, preferably at one end of the pressure box 5. The pressure box 5 constitutes a tight enclosure but comprises outlets 7 for the supply air discharge out of the pressure box 5. The outlets 7 are usually punched in one or more of the pressure box 5 wall portions 26the pressure box often consists of sheet metal. In the pressure box 5 is a static pressure built up, depending on the airflow and the total open area of the outlets 7. In the preferred embodiment, the outlets 7 have the form of elongate slots arranged at regular periodic intervals along in principle the entire longitudinal extent of the pressure box 5, and are arranged to blow out the air in two different directions, essentially perpendicular to the longitudinal extent the chilled beam 2. For change of the outlet 7 open area is a cover member 9 provided, on the outside of the pressure box 5, in a coordinated position with the outlets 7, preferably, one cover member 9 by respective side where the outlets 7 are arranged. The cover member 9 is formed as an elongate strip, and also includes elongated slot openings of corresponding length as the length of the outlet 7. By displacing the cover member 9 back and forth along the longitudinal direction of the pressure box 5, the outlets 7 are more or less covered, or not covered at all, by the cover member 9, as it comprises both covered portions and open gaps. The pressure box 5 also comprises at least one pressure measuring socket 13, representatively disposed for registration of the static pressure in the pressure box 5, and which is adapted for connection of a measuring tube 22, which measuring tube also is connected to a connector 25 on the actuator 12, see FIG. 3. When the supply air discharges out of the pressure box it arrives to a mixing chamber 8. The supply air flow, now referred L1, provides by induction effect a circulating air flow L2, which is the room air which is, through the induction, drawn through a heat exchanger 10, disposed in the chilled beam 2. This heat exchanger 10 is in customary manner liquid connected to a cooling water flow or heating water flow, alternatively both. This is fully conventional technique at chilled beams and in the fluid circuit also control valves are provided to control fluid flow through the heat exchanger 10. The fluid circuit including valves is not shown in the figures. Circulation air flow rate L2 passes through the heat exchanger 10 and becomes conditioned, i.e. cooled or heated, whereupon the air flow arrives to the mixing chamber 8 and joins the supply air flow L1. The common air flow L1+L2 is directed further out of the chilled beam 2 through an elongate outlet opening 11 on the long sides of the chilled beam 2 and further out to the room/premises A.

(9) FIG. 3 shows a view obliquely from below of a preferred embodiment of the air treatment device 1, where some parts have been removed to more clearly show the essential elements of the invention. On the chilled beam 2, the actuator 12 is arranged such that a linear movement of the actuator 12 can be transmitted to the two cover members 9, arranged on a respective wall portion 26 of the of the pressure box 5, see also FIG. 2b. In the preferred case, the actuator 12 is provided with a through shaft 23 which is slidably disposed. By that the actuator 12 displaces the shaft 23 along its length direction a linear movement will be accomplished, which movement is transmitted to the cover members 9 through an attachment 27 between the shaft 23 and cover members 9. Further, the actuator 12 is provided with a connection 25 to which one end of a measuring tube 22 is connected. The other end of the measuring tube 22 is connected to the pressure measuring socket 13 on the pressure box 5. The actuator 12 is arranged to register the static pressure in the pressure box 5 and further also adapted to register the physical position of the shaft 23, which position in turn corresponds to a k-factor corresponding with the open area of the outlets 7. Software 15 in the actuator converts the current physical location of the shaft 23 to the current k-factor and calculates the real/actual air flow in the chilled beam 2, by means of the actual static pressure in the pressure box 5. The actuator 12 also has adjustment means 28 in the form of set screws, which are used to set the minimum flow at non-presence, and further for setting within which air flows the supply air flow will vary when presencefrom normal flow to maximum flow.

(10) At non-presence in the premises A, indicated by, for example, the presence sensor 17 (see FIG. 1), the air flow is down regulated to minimum flow because the actual air flow in the chilled beam does not match the set point that apply to non-presence. Thus, the actuator 12 displaces the shaft 23 in the direction corresponding to a direction of movement for reduced flow, that is, so that the cover members 9 covers a larger part of the outlets 7, wherein the flow area is decreased. The system regulates the flow so that it is corresponding to the set point flow for non-presence. By that the static pressure and the position of the shaft 23 of the actuator is registered and compared with the set point, the correct supply air to the room is swiftly obtained. Also the fluid flow through the heat exchanger 10 can, depending on the control mode, be adjusted down to a minimum flow. At non-presence it can also be that the temperature and carbon dioxide values may have other limits than at presence mode. At detection of presence or that the temperature or carbon dioxide level is not within the targeted set points, either the flow of liquid or air, or the two in combination, are regulated. Here we discuss only the supply air flow regulation because it is within the scope of the invention. At presence and normal operation mode, the supply airflow is regulated up to a normal operation mode, and if the room temperature rises above the set point value, primarily an adjustment of the liquid flow can be done. But if that is not enough and/or the carbon dioxide level also is too high, the airflow is increased gradually to keep the comfort of the premises. Increased supply air flow L1 out of the pressure box 5 also leads to greater induction, at least up to certain levels, which also means that an increased circulating air flow L2 is drawn up through the heat exchanger 10 and conditioned by it. The actual supply airflow is balanced constantly towards current set point depending on the room condition, and the VAV regulation is individual and direct at the chilled beam 2, without any additional pressure drops beyond that yet available in the chilled beam, and the supply airflow to the premises A is really the correct.

PARTS LIST

(11) 1=air treatment device 2=chilled beam 3=supply air duct 4=air treatment system 5=pressure box 6=inlet 7=outlet 8=mixing chamber 9=cover member 10=heat exchanger 11=outlet opening 12=actuator 13=pressure measuring socket 14=room sensor 15=software 16=pressure sensor 17=presence sensor 18=temperature sensor 19=carbon dioxide sensor 20=exhaust air duct 21=air handling unit 22=measuring tube 23=shaft 24=branch duct 25=connector 26=wall portion 27=attachment 28=adjustment means A=premises L1=supply air flow L2=circulation air flow