Патент USA US2405895код для вставки
Aug. 13,1946. 7 ‘ > E, Lonwle _ 2,405,895 LOW TEMPERATURE CHAMBER REFRIGERATION _ Filed May 281 1.942 @494 f4 ' z 7 a _ J3 J2 INVENTOR BY ///; ATTORNEYS 2,405,895 Patented Aug. 13, 1946 ,UNITED STATES PATENT OFFICE 2,405,895 LOWrTEMPERATUREVCHAMBER , REFRIGERATION Erwin Lodwig, Franklin Square, N. Y., assignor to , Mobile Refrigeration, Inc., New York, N. Y., a corporation of New York Application May 28, 1942, Serial No. 444,800 6 Claims. This invention relates to refrigeration and more particularly concerns improved apparatus for rapidly cooling the atmosphere in a chamber to very low temperatures. In the development and testing of aircraft, parts thereof, and instruments and other appa ratus for use thereon, it is necessary to subject various parts and devices to the extreme condi (01. 62-402) chamber air. I have found it desirable in cham bers of the type described to provide separate refrigerant evaporating means for respectively cooling the walls of the chamber and the ‘air in the chamber. I have further discovered that by circulating the air in the chamber successively over the separate evaporating means but at a higher velocity over the air cooling evaporator than over the wall cooling evaporator means, ac tions of atmospheric'temperature and pressure cumulations of frost or ice may be removed from encountered in ?ight. These conditions include 10 the air cooling evaporator, and the accumulation temperature changes from the highest ground of frost on that evaporator when the chamber is temperature to temperatures well below 100 de closed may be avoided. I have also discovered grees below zero Fahrenheit, and pressure changes from normal atmospheric pressure at sea level to less than four inches of mercury absolute. that accumulations of frost may be quickly re moved from the inner surface of‘ a sight opening Since the conditions to be reproduced include sub atmospheric pressures, a closed chamber must be used, and in order that the operation of the in tion of air in the chamber over the window and or window in the chamber by successive circula the cooled chamber walls. Other objects, advantages, and features of the struments or devices may be observed, a window invention will be apparent from the following de 20 or sight opening is preferably provided in the scription of a typical embodiment thereof which is illustrated in the accompanying drawing. In the operation of a chamber under the condi In the drawing tions described, the formation of frost is a serious Fig. l is a sectional elevation illustrating a re-, problem. Moisture is condensed from the air frigerating. chamber provided with cooling means 25 within the chamber as its temperature is lowered and. embodying my invention; below the dew‘ point of the air, and freezes on Fig. 2 is a sectional view of the air cooling evap the evaporators or other surfaces employed to orator taken along the line 2-2 of Fig. l and cool the chamber. Further, it is frequently nec viewed in. the direction of the arrows; and essary to open the chamber while the atmosphere 30 Fig. 3 is a sectional view on a reduced scale of therein and the interior surfaces thereof are at one of the wall evaporators of the chamber illus very low temperatures, and under such conditions, trated in Fig. l. frost quickly accumulates on the cold interior Refrigerated chambers embodying the inven surfaces of the chamber, including the inner sur tion may be of any desired form and are usually faces of any windows or sight openings therein. rectangular or cylindrical. The chamber illus This frosting is ‘caused by the entry of air at room 03 01 trated in the drawing is rectangular and its six temperature and relative humidity and the sud surfaces comprise a door D and five wall sections, den condensation and freezing of moisture from of which four are illustrated in Fig. l at W, W1, such air when its temperature is lowered, by mix W2, and W3. Since the chamber is ‘substantially ture with the cold air and contact with the cold completely evacuated in use, itswalls must be surfaces within the chamber. The frost both strong enough to withstand substantially full at obscuresthe sight opening and reduces the effi mospheric pressure. This could be accomplished ciency of the cooling surfaces by partially insulat by constructing the walls of heavy gauge metal, ing them from the air within the chamber so that but I prefer instead to employ wall sections the rate of cooling of the chamber air is retarded formed of two spaced metal plates or sheets hav 45 and it is impossible to accurately observe the ing passages therebetween. This arrangement operation of devices in the chamber through the provides walls having the requisite strength and window. ‘ relatively little mass, whereby the heat load im With the above and other. considerations in posed by the walls is reduced. The arrangement mind, it is proposed in accordance withv the pres also provides passages between the wall plates so ent invention to devise an improved chamber hav that the wall sections comprise evaporators in ing cooling means capable of rapidly lowering which refrigerant may be evaporated to cool the 1 the temperature of the air in the chamber to very Walls, and, to some extent, the air in the chamber. low values without producing frost accumulations In the illustratedv embodiment, each wall sec thateither obscure a window in the chamber or tion comprises two spaced metal plates 4 and 5. chamber. ' . substantially retard the rate of cooling of the 55 3 2,405,895 connected along their edges by edge spacers 6 and at intermediate points by reinforcing ba?le spacers 7. The baffle spacers ‘l are preferably staggered as shown in Fig. 3 to provide a cir cuitous passage between the wall plates for the ?ow of refrigerant. The edge spacers S are welded "or otherwise tightly sealed to the wall plates 14 and 5 so that each Wall section forms a sealed refrigerant evaporator. The several wall sections W, W1, W2, etc., may be of identical con struction and are welded together .alcngtheir meeting edges to form an air-tight chamber. Instead of using the spacers E and 7, the plates 4 and 5 may be offset or embossed to provide 4 through a suction line 27. Condensed refrigerant may be similarly supplied to the several Wall section evaporators through the ducts 28, 29, 30, and 3|, and evaporated refrigerant is returned therefrom to the unit 25 through suction lines 32, 33, 34, and 35. It should be understood that the unit 25 will include suitable known expan sion valves and thermostatic controls to regu late the supply of refrigerant to the several to, ' evaporators in accordance with conventional practice, ' In the operation of the illustrated embodiment of’ my invention, considering ?rst the cooling of meeting areas that de?ne circuitous'refrigerant 16 the chamber and the air and equipment therein from room temperature to a low temperature re passages between the plates. The outer surfaces“ quired for test or development operations, the door D is closed and the refrigeration unit 25 and fan 22 are started. Due to the arrangement of the flue 11, the air propelled by the fan 22 is The chamber door D may be of any suitable construction, and as shown covers substantially 20 con?ned to a path closely adjacent the coil 15 and ?ns l6 of the evaporator E and flows at a allot one'surface of ‘the chamber. The door relatively high velocity over these parts, where D may be hingedly secured to a frame or ?ange as the air is circulated at lower velocities over 8. around the door opening, and may be held the inner surfaces of the chamber walls and the closed by suitable clamps or latches,not shown. pane 9 of the window 0. Refrigerant evaporates A sight opening’ or window .0 is preferably pro in the chamberwall sections W, W1, W2, etc., and vided in the chamber door D, and as shown may rapidly withdraws heat therefrom, thereby re ‘comprise a plurality of spaced glass panes 9 and ducing the chamber wall temperature. At the 10; sealed in the‘frame ll of the door. Spaced same time, the evaporator E rapidly cools the air gaskets l2 and 13 may .be provided between the of the chamber walls may be heat insulatedby any suitable material, and such insulation has been diagrammatically represented at M. dolor frame H and the chamber opening ?ange 8 30 in'the chamber, and the instruments and devices therein. As the cooling progresses, the tempera . ' ' I . ture of the chamber walls falls below the dew A-n evaporator E is provided within the charm point of the air in the chamber and belowthe ber‘for cooling the air therein and the instru freezing point, with the result that moisture is ments or other apparatus under test or observa to insure a tight closure. tion; ‘ In accordance with the present invention, means are provided for. circulating air in the chamber successively .over this evaporator and the‘inner surfaces of the chamber wall section evaporators W, W1, W2, etc. The arrangement is such that the velocity of the circulated air passing over the evaporator E .is considerably higher than that of the air passing over the ‘chamber wall surfaces. In the disclosed. embodi -ment,.the evaporator E comprises a coil I 5 having a vertically disposed heat conductingfms I76 there on, and the?nnedcbil-unitiis enclosed in a?ue or dust H. The ?ue H has a fan compartment l8 below the evaporator coil .|5.and in communi cation therewith through an opening [9. Anair ' inlet opening 20 is provided in the front wall of the ?ue l1, and an outlet opening 2| is pro vided in the front wall of the fan compartment l8. l, A fan or blower_.22 of any suitable construc condensed from the air and frozen on the inner surfaces of the walls. The temperature of the evaporator E also falls below the dew point of the air and the freezing point of water, and the accumulation of frost on the evaporator coil l5 and ?ns I 8 would also be expected. However, with the air ?owing over the evaporator E at a considerably higher velocity than over the charm ber walls, frost does not form on the evaporator E. The temperature of the instruments or other apparatus under test or observation in the cham ber also falls below the dew point and the freez ing point as these objects are cooled by the cir~ culated air, but frost does not accumulate thereon. ' . ~ The selective formation of frost on the cham ber walls rather than on the evaporator E is ap parently caused by the more rapid circulation of air over the evaporator which transfers heat thereto more rapidly than to the walls and ac tionfis disposed. to propel air at relatively high velocity through the ?ue l1, and. as shownthis 55 cordingly maintains the evaporator at a some what higher temperature than the walls. Simi fan-is disposedajdjacent the outlet opening 2| larly the absence of frost on the apparatus under of the fan compartment [3. The fan22 may be test in the chamber is believed due to the fact ' that such apparatus, being cooled by the circu The assembly comprising theevaporator E and flue I‘! is preferably spaced from the window 0 60 lated air, is at a higher temperature than the drivenby an electric motor. 23.. ' chamber walls. Regardless of the reason for this selective frost formation, the observed fact wall section W1 of the chamber with the air is that even after frost has accumulated on the inlet and outlet openings 20 and 2| directed to ward the "opposite wall of the chamber, in the 65 surfaces of the evaporator E and; on apparatus in the chamber, due to the opening of the cham illustrated embodiment toward the chamber ber door D when the surfaces andapparatus ‘are door D; ‘ . below freezing temperature, operation of the fan The evaporator coil 15 and thewall section 22 with theidoor D closed rapidly removes not evaporators are supplied with refrigerant from only the frost accumulated on the evaporator and any suitable source such as a; refrigerant com pressing and condensing unit, conventionally 70 the apparatus, but that formed on the inner sur face ‘of the glass pane 9 of the window 0 as well. represented ‘at 25. The coil 15 of the evaporator It is frequently necessary to :open ‘the cham E may be supplied with condensed refrigerant her door D to give access to instruments or de~ through‘a pipe 26-, and evaporated ‘refrigerant vices in the chamber while the air in the cham may be returned from the coil to the unit 25 and may be disposed as shown adjacent the back ber, ‘the. apparatus therein, the evaporator E, 2,405,895 v5 the inner surfaces of the chamber “61 evaporator sections,'and the inner pane 9_ of the window 0 are at temperatures well below the freezing point. Before opening the door D, the fan 22 is stopped to avoid unnecessary heating by blow ing chilled air out of the chamber. When the .door D is opened, relatively warm moist room air enters the chamber and mingles with the relatively warmer surfaces and its relative hu midity, is thereby decreased, The air then ap parently picksup moisture from these surfaces by sublimation of the frost. thereon._ Although this explanation is believed correct, it should be un derstood that the invention is in _ no way de pendent upon the accuracy thereof. I claim:, . 1 ., 1. In ‘apparatus of the type described, in ‘com the room air increases the relative humidity of 10 bination, a vclosed chamber having a: window therein, at least two evaporators disposed at the mixed air in the chamber to a point above spaced points, in said chamber and having sur saturation at the prevailing mixed air tempera faces exposedto the atmosphere therein, means ture with the result that immediate condensa for supplying refrigerant, to said evaporators tion takes place, forming a fog or mist in the whereby their exposed surfaces ‘are cooled, and 15 chamber. The temperature of the chamber means including an air propelling device for cir walls, the evaporator E,.the inner surface of the culating some of the air within said chamber suc glass pane 9 of the window 01, and any appa cessively over said evaporators and said window ratus under test in the chamber, are not only and at a higher velocity over one of said evapora well below the dew point of themixed air, but than over, the window and the other evape below the freezing point as well. Therefore, 20 tors orator, whereby frost accumulations are removed frost quickly forms on these surfaces within the from the window and from the evaporator over chamber. The formation of frost on the pane 9 which the air is circulated at the higher velocity. is particularly rapid, since with the door open, 2. In apparatus of the type described, in com the cold pane is in direct contact with warm cold air therein. The moisture introduced by moist room air. The formation of frost on ap paratus in the chamber prevents accurate ob servation thereof, particularly in the case of the dials or glass cover plates of indicating instru ments, and if permitted to remain,‘ such frost might impair the operation or accuracy of cer tain devices. When the chamber door D is again closed and the fan 22 started, the frost quickly disappears from the evaporator E and also from the inner surface of the window pane bination, a closed chamber having at least a por tion of its wall structure formed of metallic plates spaced to provide passages for the evaporation of refrigerant therebetween, an evaporator in said chamber spaced from the chamber wall structure, means for supplying refrigerant to said wall struc ture refrigerant passages and to said evaporator whereby said evaporatorand the inner surfaces of said portion of said wall structure are cooled, and means including an air propelling device for circulating air in said chambersuccessively at 9. At the same time, frost is quickly removed 35 high velocity over said evaporator and at a rela from the devices in the chamber. Removal of tively lower velocity over the cooled inner surfaces frost from the pane 9 and from the devices per of said portion of said wall structure, whereby ac mits clear observation of the devices in the cumulation of frost on said evaporator is avoided. chamber. Defrosting of the evaporator coil E 3. In apparatus of the type described, in com increases the rate at which heat is absorbed bination, a closed chamber including a wall struc thereby from the chamber air. As a conse ture formed of metallic plates secured together quence, the chamber air temperature is quickly and having passages for the evaporation of refrig lowered to the desired value, the cooling of the erant therebetween, an evaporator in said cham instruments or devices in the chamber is not delayed, and the testing or development work 45 ber, means for supplying refrigerant to said evap orator and to said wall passages whereby said proceeds rapidly. evaporator and the chamber wall structure are It is my belief that the above described de cooled, air propelling means in said chamber ad frosting of the evaporator E, the Window pane 9, jacent said evaporator and a flue closely enclos and apparatus in the chamber involves a trans ing said air propelling means and said evaporator fer of frost from these parts to the inner sur and having openings therein spaced from said faces of the chamber wall evaporator sections cooled wall structure for directing air propelled W, W1, W2, etc., and results from the difference by said means successively at a high velocity over in temperature of the several parts and the suc said evaporator and at a lower velocity over said cessive circulation of air thereover. Since the air in the chamber is circulated at a higher 55 cooled wall structure, whereby frost accumula velocity over the evaporator E than over the chamber wall evaporator surfaces, the evaporator E is maintained at a somewhat higher tempera ture than the chamber walls. The apparatus in tions on said evaporator are removed. 4. In apparatus of the type described, in com bination, a closed chamber including a wall struc ture formed of metallic plates secured together and having passages for the evaporation of re-_ the chamber which is cooled by the circulated air, 60 frigerant therebetween, an evaporator in said is at a higher temperature than the chamber chamber, a window in said chamber spaced from walls. Also, heat loss through the window struc said evaporator, means for supplying refrigerant ture O keeps the inner window pane 9 at a higher to said evaporator and to said wall passages temperature than, the chamber wall evaporator surfaces. It is therefore probable that the air 65 whereby said evaporator and the chamber wall structure are cooled, and means including an air circulating at relatively low velocity along the propelling device for circulating air in said cham surfaces of the chamber wall evaporators is ber successively at a high velocity over said evap chilled to a temperature where moisture is con orator and at a lower velocity over said cooled densed therefrom and deposited on these walls in the form of frost, reducing the moisture con 70 wall structure and said window, whereby frost accumulations are removed from said evaporator tent of the air at this point. The air thus dried and said window. or dehydrated then passes over the surfaces of 5. In apparatus of the type described, in com the evaporator E and the window pane 9, and bination, a closed chamber including a wall struc over the apparatus under test in the chamber, its temperature is raised by contact with these 76 ture formed of metallic plates secured together 7 2,405,895 and having passages for the evaporation of re frigerant therebetween,- an evaporator in said chamber, a window in said chamber spaced from said evaporator, means for supplying refrigerant to said evaporator and to said wall passages whereby said evaporator and the chamber wall structure are cooled, air propelling means in said chamber adjacent said evaporator, and a ?ue closely enclosing said air propelling means and said‘ evaporator and having openings therein spaced from said cooled wall structure for direct ing air propelled by said means successively at a high velocity over said evaporator and at a lower velocity over said cooled wall structure and said window, whereby frost accumulations on said 8 metallic plates secured together and providing passages therebetween for the evaporation of re frigerant, an evaporator in said chamber spaced from said door, means for supplying refriger ant to said evaporator and to said wall structure refrigerant passages whereby said evaporator and the chamber wall structure are cooled, air propel l-iing means adjacent said evaporator, and means for con?ning air propelled by said propelling means to a path closely adjacent said evapora tor and for directing some of the air so propelled in an uncon?ned circulatory path successively over said cooled wall structure and said window, whereby air is circulated in said chamber at a higher velocity over said evaporator and at a lower velocity over said cooled wall structure and 6. In apparatus of the type described, in com said window and frost accumulations are removed bination, a closed chamber having an openable from said evaporator and said window. door therein, a window in said door, said cham ber having a wall structure formed of spaced 20 ERWIN LODWIG. evaporator and on said window are removed.