US2371203A - Air mixing apparatus - Google Patents

Description

March 13, 1945.

H. A. WHITESEL AIR MIXING APPARATUS Filed Jan. 26, 1944 uounnh nuuuno Uuuuuu Figi.

.Inventor Hart-,g A.Whtesel Patented Mar. 13, 1945 UNITED STATES PATENT OFFICE l' I. AIR nmnllnmrrus Harry A. WhiteseL AGlen Ridge, 5.,.assig-nor `to General ,Electric .Com

vNew York` pany, a 'corporation of Application .flannel-yes, 1944, .serial No. s195771 (Cl. 13S-4 2.) .My invention relates yto .air conditioning ap- I 17 Claims.

paratus and more iparticularly to apparatus for mixing lair in .astream so that the .atmospheric conditions thereof are` uniform throughout a cross-section of ,the stream.

.the determination of the performance of airconditioning .apparatus itis frequently necessary to know the average temperature o r the .average humidity of the air in a stream; normally, however, the .atmospheric conditions prevailingover the `.cross-section Hof a stream of air vary .widelyso .that temperature measured atone point. in` the cross-section differs from that at another point. It is desirable that a single readingof ..a thermometer or .humidity indicating device besuiiicient to determine thenaverage tem- "Referring now to the drawing, Fig. 1 illustrates a calorimeter `comprising a `thermally insulfated cabinet' I0 including a compartment I I iii-which is larranged `a `heat `exchanger I2 to be tested, a compartment I 3 containing` an air -circulating fan' I4, heat exchange apparatus r4'I'.i and humidifying apparatus I6. A middle compartment 'I1 is provided :between the compart-4 ments H and I3 and lmay contain the connections l('not'shown)` to the heatv exchange apparatus for conducting Vvheat exchangefluid to they 'pera'ture .or humidity .of the stream. "Asingle reading maybe sufficient provided the stream Pis thoroughly .mixed to render the atmospheric conditions uniform throughout the cross-sectional .area of the stream.` It is desirable that apparatus for `testing the `performance of an air conditioning` system be as compact .as possible; `and in order to obtain the desired ,compactnesa .it is ,oftennecessary to provide a change in direction of. thestrearn of air. Itis an object of my i11vention`toproyide an improved apparatus for thoroughly mixing ,the air inv a .stream ,to ren- `der uniform the atmospheric 4conditions through- Aout a cross-sectionofl the stream. o

` It is another object o'f my .invention Vto provide a compact and efficient apparatus for thor- .oughly mixing the air in astream to render the atmospheric conditions thereof (uniform `through- .out .a .cross-section .of thefstream and Aincluding an improved `arrangementlfor changing the direction of the stream during the air mixing operation.

Further objects and advantages of Lmy invention will become apparent as the following deapparatus in the other compartments. Communication between the compartments II and I3 is provided Vat one end'by anair mixing apparatus and at; the other end by ya similar apparatus 2I. The cabinet 10 is, of course, provided with doors providing `access to vthe `several compartments of the -cabinet. These doorsv have not been shown 4as they are not necessary to an understanding ofthe invention. vThe calorimeter o y provides anarrangement `whereby air may be circulated over the unit I2 which is to betested and-may the'nbe returned to the compartment `I3 where its temperature and humidity'are restored `to'ytheir values before passing over the unitIZ During the operation oi the vapparatus llustrated,`;the 'nit 4 I2 Iis supplied with heating .scription proceeds,` and `the features of novelty .which characterize my invention will be Jpointed .out `with particularity in the claims annexed to `and forming part of thisspecication.

`.For a .better `,understanding of my invention .reference may be `hadto thev accompanying drawing in which Fig. 1 yis a'sectional elevation view of a calorimeter lfor testing/heat exchangeunits .-and ,including ,air mixers embodying my inven- Etion; Fig. .2. is an enlarged perspective view of -the ,air mixing apparatus shown in Fig.` 1 with the air v or cooling uid at `a predetermined temperature and air-is circulated `through the cabinet by operation of the fan M. `The air leaving the fan I4 passes through the -mixing device 2l andis discharged from the device intovthe cabinet Il, the air. in fthe stream discharged from the device 2| being of uniform condition throughout its cross-sectional area so that a thermometer -orother Vtemperature measuring device 22 and a relativehumiditymeasuring device 23 may be placed 4atthe outlet ofthe apparatus` 2| to determine the average temperature and average rela-tive humidity ofthe airsupplied to the heat exchanger I2. After the air is passed over the -unit I2, `it enters themixing vapparatus 20 and is discharged therefrom into the compartment` I3, the average'temperature and -humidity ofthe air discharged to the compartment I`3 being uniform throughout the lcross-section of the discharge `outlet so that la thermometer or utemper- -ature measuring `device 25 and a relative humidity `measuring-device 26 may be employed to determine the average temperature and Lrelative humidity of the air .as a result of itsyhaving passed over the heat exchange unit I2. This 'air then passes overthe heat 4exchanger I5 where fitis either heated or cooled kand ,over the humidvi-fgying apparatus I6 so that the air `returned to the fan |4 is restored to a predetermined condition before its recirculation to the compartment The calorimeter thus comprises an apparatus for circulating air in a closed path under conditions such that it is supplied to the heat exchange unit to be tested at known temperature and relative humidity and so that the performance of the heat exchange apparatus may be measured.

The details of the construction of the air mixers 29 and 2| are shown in Fig. 2. Both the mixers and 2| are of the same construction. Fig. 2 may be considered as a view 0f the mixer 2| since its inlet and outlet correspond in position to those of the mixer 2|. The mixer as illustrated comprises a rectangular frame work constructed of angle iron members 21, and is provided with an inlet over which is secured a foraminous plate or screen 28 and an outlet over which is secured a similar screen 29, the mixer being completely closed except for the inlet and outlet. The screens 28 and 29 and the several walls of the apparatus are secured to the angle iron members 21 to form a rectangular box-like duct structure. These screens serve to make the velocity of the air uniform over the cross-sec,- tional area at the inlet and outlet of the device. The mixer is divided into three compartments by solid partitions 30 and 3|, the lower comparte ment, indicated at 32, being the inlet compartment, the upper compartment 33, the outlet compartment,and the intermediate compartment 34 being formed between the inlet and outlet com.. partments. The front side of the intermediate compartment 34 is closedv by a wall 35 between the screens 28 and 29. Communication between the compartments 32 and 34 is afforded by an i opening 36 formed at the rear of the partition 30 remote from the inlet 'and betweenv the partition and the side and rearwalls of the mixer. Communication between the compartment 34 and the outlet compartment 33 is afforded by an opening 31 in the partition 3| between the rear wall and the other side wall of the mixer. An upright baille or partition member 38v is provided so that it extends transversely between the partitions 30 and 3| and prevents direct passage of air between the openings 36 and 31, the partition 38 dividing the compartment 34 into two sec- 1 'z tions maintained in communication through an opening 39 formed between the partition 38 and the front wall of the mixer. It will thus be evident that the air stream passing through the inlet screen 28 is directed in a tortuous path l through the three compartments of the mixer. A mixing apparatus of this general type but which does not provide a reversal of the direction of the air between the inlet and the outlet is described and claimed in my copending applicai,

tion, Serial No. 511,270. led November 22, 1943, and assigned to the same assignee as my present invention.

I have found that by making the openings 36, 31 and 39 of a cross-sectional area less than onehalf of the cross-sectional area of the inlet 28, and preferably of the order of one-third the area of the inlet, the air stream passing through the apparatus is thoroughly mixed. This thorough mixing is further facilitated by making the compartment 34 of smaller cross-section and volume than the compartments 32 and 33 so that the air inpassing from the inlet compartment to .the compartment 34 is reduced in average cross-section and is correspondingly increased in average cross-section on passing into the outlet compartment 33. The inlets and outlets are preferably of the same cross-sectional area. The mixing apparatus is preferably rectangular in form and the cross-sections of the compartments and the openings are also preferably rectangular, and the inlet and outlet openings between the compartments are also rectangular.

A'n apparatus constructed as shown in Fig. 2, when tested, provided thorough mixing of the air, as is illustrated by curves of the graph of Fig. 3. Fig. 3 represents the temperatures prevailing in eighteen positions over the inlet and outlet of the apparatus shown in Fig. 2, the curve 40indicating thek temperatures prevailing at the inlet and a curve 4| the temperatures at corresponding positions at the outlet. Each curve is broken into vthree parts connected by ,dotted lines and each part comprises six temperature readings in top, middle and bottom rows, respectively, of the inlet and outlet openings. Itis readily apparent that the temperaturesl at the inlet, as indicated by the curve 40, vary widely Whereas the temperatures over the cross-sectional area at the outlet are substantially constant. It is readily apparent from Fig. 3 that the possibility of error due to measuring the temperature at a single point in order to determine the average temperature has been minimized. i

The dimensions of the air mixing apparatus illustrated in Fig. 2 are selected so that no undue l pressure drop will, exist in the calorimeter and are selected in accordance with the capacity of the fan |4.

From the foregoing it is readily apparent that I have provided a simple and easily constructed arrangement which makes it possible to mix thoroughly the stream of air passing through a duct and, furthermore, is such that the direction of the stream of air may be reversed, this construction lending itself particularly to closed circuit apparatus such as the calorimeter illustrated.

,While I have described my invention in connection with a calorimeter for determining the performance of heat exchange apparatus,` other applications will readily be vapparent to those skilled in the art. I do not, therefore, desire my invention to belimited to the particular construction illustrated and described, and I intend by the appended claims to cover all modifications which fall within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An apparatus for effecting thorough mixing of the air in a stream to provide uniform atmospheric conditions throughout a cross-section of the stream comprising a duct structure having an inlet and an outlet, partitions arranged in the duct for dividing said duct into two end compartments communicating respectively with said inlet and said outlet and a third compartment between said end compartments, said partitions being arranged toprovide openings between said end compartments and said third compartment remote from said inlet and said outlet, a baule in said third compartment extending transversely between said partitions for preventing direct passage of air from' one of said openings to the other and dividing said third compartment into two sections having an `opening therebetween whereby air passingl from said inlet to of `the 4air `in a stream 'less than one l1"V the-area of 'said ing `an area inlet. x

2. .An apparatus for pheric conditions throughlloutA a' cross-z-'secti'on of he stream comprising a rectangular duct strucoutlet, a baiiiein said third compartment extending transversely between said partitions for preventingvdirect passage of air from one of said openings to the other and dividing saidthird compartment into two sections having an openingtherebetween whereby air passing from said inlet to said outlet is directed through said compartments in a tortuous path, all of said openings being of substantially the same size and each having an area of the order of one-third that of said inlet. V

3. An apparatus for effecting thorough mixing of the air in a stream to provide uniform atmospheric conditions throughout a cross-section of the stream comprising a rectangular duct structure having a rectangular inlet and a rectangular outlet in the same wall thereof, partitions arranged in the duct for dividing said duct into two rectangular end compartments comi muncating with said inlet and said outlet and a third rectangular compartment between said end compartments, said partitions bein-g arranged to provide rectangular openings between said end compartments and said third compartment remote from said inlet and said outlet, a baille in said third compartment extending transversely between said partitions for preventing direct passage of air from one of said openings to the other and dividing said third. compartment into two Sections having anopening therebetween whereby air passing from said inlet to said outlet is directed through said compartments in a tortuous path, all of said openings being of substantially the same size andV each having an `area less than one-half the area of said inlet.

4. An apparatus for effecting thorough mixing of the air in a stream to provide uniform atmospheric conditions throughout a cross-section of the stream comprising a duct structure havingv an inlet and an outlet, partitions arranged in the duct for dividing said duct into two end compartments communicating respectively with said inlet and said outlet and a thirdA compartment between said end compartments, said third compartment having a volume substantially less than the volume of one of said end compartments, said partitions being arranged to` provide openings between said end compartments and said third compartment remote from said inlet and said outlet, a baille in said third compartment extending transversely between said partitions for preventing direct passage of air` from one or said openings to the other and dividing said third compartment into two sections having an opening therebetween whereby air passing from'said inlet to saidv outlet is directed through said compartments in a tortuous path, all of said openingsbeing of substantially the same size and each i having an area less than one-half the area of said inlet whereby the cross-sectional area of the stream' vpassing 1through -fsaid duct .iisfreduced lo'n passing from said inlet'to said third `compartment 4vand is `increased upon passingffromwsaid third compartment toward said outlet. i

5. An apparatus for effecting thorough Amitrin-g of theair in a stream to provide uniform at- 'inospheric conditions throughout .a cross-section of 'the `stream comprisinga virectaiigula'r duct structure *having an. inlet and Yan outlet in the same side wall thereof, partitions arranged in the duct for dividing said duct into two rectangular end compartments communicating respectivei ly with said inlet and said outlet, andfa third rectangular compartment between said end compartments, said third compartment having a volume substantially less than the volume of either of said end compartments, said partitions being arranged to provide rectangular openings between said end compartments and said third compartment remote from said inlet and said outlet, a baille in said third compartment extending transversely between said partitions for preventing direct passage of air from one of said openings to the other and dividing said third compartment into two sections having an opening therebetween whereby air passing from said inlet to said` outlet is directed throughA said compartments in a tortuo-us path, each of said openings having an area less than one-half the area of said inlet whereby the cross-sectional area of the stream passing through said-duct is reduced on passing from said inlet to said other compartment, and is increased upon passingfrom said third compartment toward said outlet.

6. An apparatus for effecting thorough mixing of the air in a stream to provide uniform atmospheric conditions throughout a cross-section of the stream comprising a ductstructure having an inlet and an outlet, partitions arranged in the duct for dividing said duct into two end compartments of substantially the same size communicating respectively with said inlet and said outlet and a third compartment between said end compartments, said third compartment havl ing across-sectional area of approximately twothirds the cross-sectional area of each of said end compartments, said partitions being arranged to provide openings between said end compartments `and said third compartment remote from said inlet and said outlet, a baiie in said third compartment extending transversely between said partitions for preventing direct passage of air from one of said openings to the other and dividing said third compartment into two sections having an opening therebetween whereby air passing from said inlet to said outlet is directed through said compartments in a tortuous path, all of said openings and the cross-sectional area of each of said two sections being of substantially the same size and each having an area less than one-half the area of said inlet whereby the crosssectionalarea of the stream passing through said vduct is reduced on passing from said inlet to said third compartment and is increased upon passing from said third compartment toward said outlet. y 7. An apparatus for eiecting thorough mixing V oi" the air in a stream to provide uniform atmospheric conditions throughout a cross-section of the stream comprising a rectangular duct structure having a rectangular inlet and a rectangular voutlet in the same wall thereof, said inlet andoutlet having the same cross-sectional area, partitions arranged in the duct for dividing said duct into two rectangular end compartments communicating with said inlet and said outlet and a l third rectangular compartment between said end compartments, said third compartment having a. cross-sectional area approximately two-thirds that of said inlet, said partitions being arranged to provide rectangular openings between said end compartments and saidthird compartment remote from said inlet and said outlet, a baffle in said third compartment extending transversely between said partitions for preventing direct passage of air from one of said openings to the other and dividing said third compartment into two sections having an opening therebetween whereby air passing from said inlet to said outlet is directed through said compartments in a tortuousA path, all of said openings being of sub stantiallyythe same size and each having an area substantially one-third the area of said inlet.

HARRY A. WHITESEL.

Images