US2962952A

US2962952A - Air conditioning unit

Info

Publication number: US2962952A
Application number: US643427A
Authority: US
Inventors: William L Mcgrath
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1957-03-01
Filing date: 1957-03-01
Publication date: 1960-12-06
Anticipated expiration: 1977-12-06
Also published as: FR1198798A; BE565272A; GB820696A; BE565239A

Description

Dec. 6, 1960 w. MOGRATH 2,962,952

' AIR CONDITIONING UNIT Filed March 1. 1957 2 Sheets-Sheet 1 F I G. I

IN VEN TOR.

WILLIAM L. McGRATH.

BY WJM ATTORNEY Dec. 6, 1960 Filed March 1, 1957 www- W. L. M GRATH AIR CONDITIONING UNIT 2 Sheets-Sheet 2 INVENTOR. WILLIAM L. McGRATH.

WJM

ATTORNEY;

AIR CONDITIONING UNIT William L. McGrath, Syracuse, N.Y., assignor to, Carrier Corporation, Syracuse, N.Y.,'a -corporatiou of Delaware Filed Mar. 1, 1957, Ser. No. 643,427 4 Claims. (C l. 98-38) This invention relates to air conditioning units and more particularly to improved air conditioning units containing slot type primary air discharge means and means to act therewith to induce a stream of secondary air from the area being conditioned through a heat exchange member in the unit and to efiiciently and quietly 'mix with the stream of primary air, the mixture of primary air and secondary air being discharged within the area being treated.

In Carrier Patent No. 2,363,294, granted November 21, 1944, there is disclosed an air conditioning system for multi-room buildings which contemplates a supply of conditioned air from a central station at high velocity and static pressure through small conduits to room units placed in the rooms being conditioned. Each room unit.

includes a heat exchanger through which cold or hot water may be passed, depending upon temperature conditions exteriorly of the building. A stream of conditioned primary air (cold or warm) from the central stationv is discharged into the unit at a velocity such as to induce a stream of secondary air from the room into the unit through the heat exchanger to mix therewith. The mixture of streams is then discharged into the room to cool or heat the same.

The system disclosed in the Carrier patent has been acknowledged as the most commercially desirable system available. Owners of buildings such as hotels, office build I ings, etc., have also recognized the superior results obtainable from the Carrier system and insist on the use of such system in their buildings when superior results are desired.

The extensive use of glass in buildings has robbed these buildings of insulation and caused large transmission losses for which these units must compensate. Not only have these glass windows increased the load, but they have also come closer to the floor level, further decreasing the space available for the unit itself. Present day units, therefore, must be small and highly effective.

In meeting these requirements, the unit should be fabatent' comprises a casing having a plenum member therein, said plenum member being connected to a source of primary air. Air discharge means are connected to the plenum; a heat exchange member adapted to be connected to a source of heat exchange medium is located within the unit, the discharge means of the primary air being of a slot type to induce a stream of secondary air from the area being conditioned through the heat exchange member into heat exchange relation with medium passing therethrough to mix with the primary air being discharged from the slot nozzle and conduit means for passing the air through the primary air stream so that an induction ettectwill take place on both sides of the slot nozzle.

The attached drawings. illustrate a preferred embodiment of my invention in which:

Figure l is a perspective view of an air conditioning unit of the invention installed in a room being conditioned;

Figure 2 is a sectional view taken from the side of the unit;

Figure 3 is a sectional view taken from the front of the unit;

Figure 4 is a fragmentary view of the slot type nozzle utilizing the present invention; and

Figure 5 is a plan view of a modification of the inven tion shown in Figure 4.

Referring to the attached drawings, there is shown in Figure 1 an air conditioning unit 1 placed beneath the window of a room being treated.

casing 2 in which there are located a discharge opening '4 and an inlet opening 3. These openings each consist of a series of louvered openings through which a stream ricated at a minimum cost so as to render the use of this system competitive with other systems. One of the suggested solutions to this cost problem resides in the use of an inexpensive slot type nozzle in the units. It has been found, however, that at the high pressures customarily employed, the slot type nozzle is prohibitively noisy and unsatisfactory.

The chief object of the present invention is to provide an improved low cost induction unit for air conditioning systems.

An object of the invention is to provide an inexpensive high capacity unit capable of operating at low noise levels.

A still further object is to provide a low'noise level induction unit, utilizing high pressure primary air discharged through slot type nozzles located within the unit. Other objects of my invention will be readily perceived from the following description;

This invention relates to an air conditioning unit for usein the air conditioning ofmulti-room buildings which of secondary air is induced into the unit and a mixture of primary and secondary air is discharged from said unit. There is located adjacent the opening 3 a heat exchange member 10 more fully described hereinafter.

A plenum 5 is located at the bottom portion of the casing 2 and it consists of an elongated chamber extending the length of the casing, being suitably insulated by material 7 and having an air inlet 6 through which primary air is passed into the plenum. This primary air originates at a central station (not shown); is passed into the plenum from whence it is discharged through the nozzle 8 into' the unit.

The nozzle 8 consists of an elongated slot through which air is passed to the chamber above the plenum. As the air passes through the nozzle, secondary air is drawn in from the room through the opening 3 then through the heat exchange member 10. The primary and secondary air streams are then mixed.

Slot type nozzles have been previously used in low pressure air conditioning systems. In these particular systems the pressure of the primary air was suificiently low as not to raise any serious noise problems. However, with the diminishing amount of space allotted to the induction unit as previously outlined, it has become extremely necessary that the air quantities and the amount of heat exchange handled by the induction unit be substantially increased. This problem has been partially solved by improved heat exchangers; however, with the increased pressures utilized in these particular units, the noise level has also increased to a point where slot type nozzles have become unsatisfactory in operation and there has been a marked departure from the use of nozzles of the Small circular nozzle openings have found favor because of their more stable operation and because they provide-much lower noise levels in operation. However, this type nozzle is more expensive when it is realized that production thereof entails the drilling of hundreds of small holes into a nozzle sheet.

Before the trend to small circular openings in nozzles,

Patented Dec. 6, 1960 air passing:therethroughn It is extremely important-that the cdgesof-the slot-be precise 'and uniform andthat a uniformtidistauce betweenthese edges extend the entire] length: of the nozzle. Itis believed thatthe increase in noise level of the slot 'nozzle'is at -leastpartly due torthe transverse'instability of the air stream.- For-example: in

a long-slot there areno longitudinal means to direct'the air stream. 1 As the air enters the plenum there is a component of air velocity in a direction-longitudinal*to the;-' slot which is present'in'the airas 'it passes through the nozzle.

it passes through-the nozzle "which creates' a plurality of eddies-or vortices which arecapableof moving transversely, resulting in a distinctive noise: t Should the particular nozzle length-be in'some way tuned to a particular frequency, a deep hum may also result in the operation of the unit.

Figure 4 illustrates a type of nozzle contemplated for the present unitfor the purpose of controlling the previously mentioned eddies with a resulting decrease in the noise level of the unit. In this figure there is shown an opening 21which constitutes the nozzle in nozzle sheet 20; this opening is created by upwardly

bent lips

22 and 23 which tend to converge. The edge of the lipsmay be provided with either a sawtooth edgeor an undulating edge; the tips of the edge may be bent inwardly. The

Because of this lack of directingmeans 'in the nozzle there is an inherent instability of the air stream as purpose of such a construction is toprovide an'unevenness in the slot opening in such a manner as to control the size and location of the eddies which are normally formed during the operation of a slot type nozzle.

Figure 5 shows a modificationof the nozzle construction illustrated in Figure 4. This figure illustrates a slot type'nozzle formed in a single plane in a nozzle sheet 31. This nozzle is in the shape of an irregular slot formed by the undulating

edges

33 and 34. These edges have'high points 36 and 37 which are'dire'ctly opposite on the sides of the nozzle opening. By such a construction a similar effect is derived as is acquired from the construction shown in Figure 4. By this type of construction the eddies are positively determined by the increase and decrease of the slot opening. By controlling the size and also the location of these eddies substantiallyquiet operation is obtained from the induction unit.

Located above the plenum between the opening 3 and the nozzle 8 is a heat exchange member 10 which comprises a plurality of parallel extended fin members having a general trapezoidal shape. At the end of the heat exchange member adjacent to nozzle 8 the heat exchange fin members 11 have their greatest area. However, as the distance from the nozzle increases the surface area of the fin members decreases. A plurality of tubes 12 are shown which are connected into a single circuit through which heat exchange medium is passed. The fins 11 are attached to these tubes and act as an extended surface therefor. The aforementioned heat exchange medium originates from a central station of the air conditioning system and may consist of either hot or cold water.

As the air is discharged from the nozzle 8, secondary air is induced through the opening 3 from the room. This secondary air because of the extended surface of the heat exchange member 10 is placed into heat exchange relation with the medium passing through the tubes 12. The treated air then mixes'with the primary air discharged from the nozzle 8 and themixture is then discharged through the outlet 4 of the unit into the room.

Referring to Figure 2, it will be noted that as the secondary air passes into the unit there is a tendency for the secondary air, after it passes through the heat exchange member 10, to mix with the primary air issuing fromthe discharge nozzle 8 on the front side of the nozzle in the area between the' nozzle and the heat exchange member 10. There is also created a low pressure area on the back side of the nozzle between the nozzle and the wall 9. The inefliciencybf such a construction is obvious. Air enters the unit and mixes on the front side of the nozzle; however, the rear section of the nozzle is isolated so as to be unable to participate in the induction and mixing effect with the secondary air.

In order to morefully use the capacity potential of slot type nozzle, the presentinvention envisions the use of 'a plurality of censure; '13 passing through the primary air stream; thereby putting 'the rear section of the nozzle 8 into communication with the air passing through the opening 3 and the heat"exchang'e member 10.

In Figure 3, there is shown a sectional view of the unit indicating the fro'rit 'ofthe unit minus the heat exchange member 10. This view illustrates that the plenum extends the entire length of the unit and is substantially covered with insulatingmaterial. The'prim'ary air supply duct'is connected to the centralstation of the air conditioning system from whence primary air is passed to the plenum 5 of the unit. The air leaves the plenum 5 through the longitudinal slot nozzle 8, passes upwardly about the

conduit members

13, 14 and 15, and is confined by the baffiemembers 16 and 17 and discharged from the unit through the discharge opening 4.

This particular figure illustrates the nature of

conduits

13, 14 and 15; It will benoted thatthese conduits'have a streamlined shape," very similar to a teardrop in crosssection." This type of construction has been found to offer the least amount of resistance to the primary air flow. As can be seen, the air which is discharged through the nozzle passes upwardly and these conduits are in the dir'ec'tp'ath of the air stream. By suitable sizing and shaping'these conduits, a minimum amount of resistance is provided to'impede the primary air stream. Furthermore, this shape permits conduits of adequate size so as to permit a substantial amount of air to pass through the inlet 3, heat exchanger 10 and through the conduits to the rear section of the nozzle 8 where a substantial induction and mixing effect is acquired.

In order to obtain uniform air flow through the heat exchange member 10, the fin members 11 of the heat exchange member have a general trapezoidal shape as previously mentioned. This provides a path of air through the heat exchange member of decreasing resistwice to said secondary air stream as it passes therethrough. This particular construction is provided to compensate for "the decrease in inductive effect as the distance from the nozzle 8 increases. Adjacent to nozzle 8 the inductive effect is high; however, at the upper part of the heat exchange member 10, this effect reaches a minimum. To compensate for this and to make more efficient use of the heat exchange member, the trapezoidal fin member preferably is incorporated into this particular plate fin coil. The construction illustrated by being able to make use of the front and rear sections'of the primary air stream issuing from the plenum creates a greater inductive effect than can normally be acquired by the single side of the air stream. This also permits the use of a deeper heat exchange member which is a direct result of the increased inductive effect acquired by the use of the rear portion of the primary air stream.

It will be noted that from the previous description there has been shown an induction unit capable of makinguse of a slot type nozzle which is an extremely economical item to manufacture compared with similar nozzle constructions requiring the drilling of hundreds of circular holes in a single nozzle sheet, or in some casesthe molding of plastic nozzle clusters having a plurality of nozzle openings oriented in such a manner as to make necessary a diflicult manufacturing process. The slot type nozzle is extremely easy to manufacture and the type herein employed does not require minute clearances normally necessary; The use of serrations or undulations permits variances in manufacturing process which will not result in any subsequent noisy operation of the unit.

While I have described a preferred embodiment of the invention, it will be understood that the invention is not limited thereto, since it may be otherwise embodied within the scope of the appended claims.

I claim:

1. In an air conditioning unit, the combination of a casing, a plenum member placed in said casing, means defining an outlet in said casing, means defining an inlet in said casing, said plenum being connected to a source of primary air, a nozzle member having an elongated slot therein associated with said plenum and extending substantially parallel to said inlet whereby the discharge of primary air through said slot induces a stream of secondary air through the inlet to mix with the primary air being discharged from the plenum, and hollow, conduit means placed above the slot in the unit forming passages for secondary air from the front of the unit rearwardly over the slot so that said secondary air may be induced into the primary air stream at the rear por- 'tion of said nozzle member.

2. An air conditioning unit according to claim 1, in which the conduit means has a general teardrop crosssection.

3. An air conditioning unit according to claim 2 in which the nozzle member forms an elongated slot having edges having a substantial sawtooth configuration.

4. An air conditioning unit according to claim 2, in which the edges of the nozzle slot are undulating.

References Cited in the file of this patent UNITED STATES PATENTS 612,480 Stevens Mar. 21, 1899 2,122,168 Woolley June 28, 1938 2,140,305 Ashley et a1. Dec. 13, 1938 2,287,267 Palmer June 23, 1942 2,345,536 Keep Mar. 28, 1944 2,567,758 Ashley Sept. 11, 1951 2,778,688 Carl Jan. 22, 1957 2,783,979 Blum Mar. 5, 1957 2,854,915 Carr Oct. 7, 1958 FOREIGN PATENTS 705,873 Great Britain Mar. 17, 1954